Golf club

A golf club 100 includes a tip engagement part RT having a reverse-tapered shape and being disposed at a tip end portion of a shaft 300, and a screw member 600. The tip engagement part RT includes a sleeve 400 fixed to the tip end portion of the shaft 300. The sleeve 400 has a sleeve-side connection part 410. The screw member 600 has a screw-side connection part 602 that can be detachably connected to the sleeve-side connection part 410, and a male screw part 604. The head 200 has a female screw part 220. When the screw member 600 is rotated in a first direction, the screw member 600 presses the tip engagement part RT in an engaging direction. When the screw member 600 is rotated in a second direction, the screw member 600 pulls the tip engagement part RT in an engagement releasing direction.

The present application claims priority on Patent Application No. 2017-110201 filed in JAPAN on Jun. 2, 2017, the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a golf club.

Description of the Related Art

A golf club including a head and a shaft detachably attached to the head has been proposed.

Each of US2013/0017901 and U.S. Pat. No. 7,980,959 discloses a golf club including a head and a shaft detachably attached to the head. In these golf clubs, a sleeve is attached to a tip end portion of the shaft, and a shaft hole provided in the sleeve is inclined. In these golf clubs, an inclination direction of a shaft axis is changed depending on a fixed position of the sleeve in a circumferential direction. This change enables a loft angle, a lie angle, and a face angle to be adjusted.

Japanese patent No. 5645936 (US2010/0197423) discloses a golf club having a shaft adapter and a head adapter. The degree of freedom of an inclination direction of a shaft axis can be improved by the shaft adapter and the head adapter.

Japanese Patent Application Publication No. 2006-42950 discloses a golf club including: a retaining part bonded to a tip end portion of a shaft; a pair of angle adjustment parts which externally surround the retaining part, and a fixing nut which is screw-connected to male screw parts formed on upper end portions of the angle adjustment parts.

SUMMARY OF THE INVENTION

In a conventional technique, a sleeve is fixed to a head by using a screw that is screw-connected to the sleeve. The screw requires high strength. In addition, the conventional technique places a significant burden on the screw. Furthermore, the degree of freedom of angle adjustment is limited.

A possible solution for these problems is to use a configuration using reverse-tapered fitting. However, the reverse-tapered fitting may cause backlash. Tightening the reverse-tapered fitting to solve the problem of backlash makes it difficult to release the fitting.

It is an object of the present disclosure to provide a golf club capable of enjoying the advantage of the reverse-tapered fitting while solving the problem thereof.

In one aspect, a golf club may include: a head having a hosel part; a shaft; a tip engagement part having a reverse-tapered shape and being disposed at a tip end portion of the shaft; and a screw member. The tip engagement part may include a sleeve having a reverse-tapered shape and being fixed to the tip end portion of the shaft. The hosel part may include a hosel hole. The hosel hole may include a reverse-tapered hole having a shape corresponding to a shape of an outer surface of the tip engagement part. The tip engagement part may be fitted to the reverse-tapered hole. The sleeve may have a sleeve-side connection part at a tip end portion thereof. The screw member may have a screw-side connection part that can be detachably connected to the sleeve-side connection part, and a male screw part. The head may have, on a lower side of the hosel hole, a female screw part that can be screw-connected to the male screw part. When the male screw part is rotated in a first direction with respect to the female screw part, the screw member may press the tip engagement part in an engaging direction. When the male screw part is rotated in a second direction with respect to the female screw part while maintaining connection between the sleeve-side connection part and the screw-side connection part, the screw member may pull the tip engagement part in an engagement releasing direction.

In another aspect, by the rotation in the first direction, the screw member may press the tip engagement part in the engaging direction, and the sleeve-side connection part may be inserted to the screw-side connection part. The connection may be automatically completed by the sleeve-side connection part being inserted to the screw-side connection part.

In another aspect, the screw member may include: a screw body having the male screw part; a first member constituting an outer circumferential surface of the screw-side connection part; a second member positioned inside the first member; a third member positioned inside the second member; a first elastic body that is disposed between the first member and the second member, and biases the first member to a sleeve side with respect to the second member; a second elastic body that biases the third member to the sleeve side; and an engagement ball disposed in a ball housing hole penetrating between an inner surface and an outer surface of the second member. The sleeve-side connection part may have an engagement recess. In a non-connected state, the engagement ball may be projected outside the second member by the third member being positioned inside the engagement ball, and, by the projected engagement ball, the first member may be located at a first position at which movement thereof to the sleeve side is regulated. In a connected state in which the connection has been achieved, the third member may be moved to a position at which the third member is removed from inside of the engagement ball by the sleeve-side connection part, the engagement ball may fall in the engagement recess of the sleeve-side connection part, and the movement regulation on the first member by the engagement ball may be released, whereby the first member may be moved to a second position at which the projection of the engagement ball to the outside is prevented.

In another aspect, the screw member may include: a screw body part having the male screw part; an elastic deformation part extending from the screw body part to a sleeve side and constituting the screw-side connection part; and a rotating engagement part to which a wrench for rotating the screw member can be inserted. The rotating engagement part may have a through hole penetrating the screw body part, and an inner surface of the elastic deformation part that extends continuously with the through hole. The elastic deformation part may have an engagement projection at an end portion thereof on a sleeve side, and the end portion on the sleeve side is a free end. The sleeve-side connection part may have a hollow portion opened on a side of the screw member, an inner surface defining the hollow portion, and an engagement recess provided on the inner surface. In a natural state, the elastic deformation part including the engagement projection may exhibit a shape that can be inserted to the hollow portion with rotation of the screw member in the first direction. When the wrench is inserted to a position at which the wrench abuts on the inner surface of the elastic deformation part, the elastic deformation part may be elastically deformed so as to be positioned at a position at which the engagement projection of the elastic deformation part can be engaged with the engagement recess.

In one aspect, a screw member may be used for a golf club including: a head having a hosel part; a shaft; and a tip engagement part having a reverse-tapered shape and being disposed at a tip end portion of the shaft. The tip engagement part may include a sleeve having a reverse-tapered shape and being fixed to the tip end portion of the shaft. The hosel part may include a hosel hole. The hosel hole may include a reverse-tapered hole having a shape corresponding to a shape of an outer surface of the tip engagement part. The tip engagement part may be fitted to the reverse-tapered hole. The sleeve may have a sleeve-side connection part at a tip end portion thereof. The screw member may have a screw-side connection part that can be detachably connected to the sleeve-side connection part, and a male screw part. The head may have, on a lower side of the hosel hole, a female screw part that can be screw-connected to the male screw part. When the male screw part is rotated in a first direction with respect to the female screw part, the screw-side connection part may be connected to the sleeve-side connection part with progression of the screw-connection. When the male screw part is rotated in a second direction with respect to the female screw part, while maintaining connection between the sleeve-side connection part and the screw-side connection part, the screw member may pull the tip engagement part in an engagement releasing direction.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments will be described in detail with appropriate references to the accompanying drawings.

Unless otherwise described, “a circumferential direction” in the present application means a circumferential direction of a shaft. Unless otherwise described, “an axial direction” in the present application means a direction of a center line of the shaft or a hosel hole. Unless otherwise described, “an axial perpendicular direction” in the present application means a direction orthogonally crossing the axial direction of the shaft. Unless otherwise described, a section in the present application means a section along a plane perpendicular to the center line of the shaft. Unless otherwise described, a grip side is defined as an upper side, and a sole side is defined as a lower side.

FIG. 1shows a golf club100which is a first embodiment.FIG. 1shows only the vicinity of a head of the golf club100.FIG. 2is a perspective view of the golf club100as viewed from a sole side.FIG. 3is an exploded perspective view of the golf club100.

The golf club100has a head200, a shaft300, a sleeve400, a spacer500, and a grip (not shown in the drawings). The sleeve400and the spacer500constitute the tip engagement part RT. The tip engagement part RT is disposed at a tip end portion of the shaft300. An outer surface of the tip engagement part RT is formed by the spacer500.

The type of the head200is not limited. The head200of the present embodiment is a wood type head. The head200may be a hybrid type head, an iron type head, a putter head or the like. The wood type head may be a driver head, or may be a head of a fairway wood.

The shaft300is not limited, and a commonly used shaft may be used. For example, a carbon shaft and a steel shaft may be used.

Although not shown in the drawings, the shaft300has a diameter varying with an axial direction position thereof. The diameter of the shaft300is increased toward the grip side. The sleeve400is fixed to the tip end portion of the shaft300. The tip end portion of the shaft300is the thinnest portion in the shaft300.

In the present embodiment, the number of the spacers500is one. The spacer500may not be present. The number of the spacers may be two. That is, two spacers may be stacked. In other words, the spacer may be double-layered. The number of the spacers may be three or more. For example, three spacers may be stacked. In other words, the spacer may be triple-layered.

The head200has a hosel part202. The hosel part202has a hosel hole204. The hosel hole204has a reverse-tapered hole206. The shape of the reverse-tapered hole206corresponds to the shape of the outer surface of the tip engagement part RT. The shape of the reverse-tapered hole206corresponds to the shape of the outer surface of the spacer500. In an engagement state, the outer surface of the tip engagement part RT (the outer surface of the spacer500) is brought into surface-contact with the reverse-tapered hole206. The outer surface of the tip engagement part RT has a plurality of (four) planes, and all of the planes are brought into surface-contact with the reverse-tapered hole206.

The hosel part202(reverse-tapered hole206) exists over the whole circumferential direction. The hosel part202(reverse-tapered hole206) is continuous without a gap in the whole circumferential direction. The hosel part202is not split in the circumferential direction. The hosel part202does not have a slit (hosel slit) formed such that a part of the hosel part in the circumferential direction is lacking. The hosel part may have the slit. An embodiment having the slit will be described later.

As with a usual head, the head200has a crown208, a sole210, and a face212(seeFIGS. 1 to 3).

As shown inFIG. 3, the sleeve400has an inner surface402and an outer surface404. The inner surface402forms a shaft hole. The sectional shape of the inner surface402is a circle. The shape of the inner surface402corresponds to the shape of an outer surface of the shaft300. The inner surface402is fixed to the tip end portion of the shaft300. That is, the sleeve400is fixed to the tip end portion of the shaft300. An adhesive is used for the fixation.

The outer surface404is a pyramid surface. The outer surface404is a four-sided pyramid surface. The sectional shape of the outer surface404is a non-circle. The sectional shape of the outer surface404is a polygon (regular polygon). The sectional shape of the outer surface404is a tetragon. The sectional shape of the outer surface404is a square. The area of a figure formed by a sectional line of the outer surface404is increased toward a tip side of the shaft300. That is, the sleeve400has a reverse-tapered shape.

The sleeve400has a sleeve-side connection part410. The sleeve-side connection part410is provided at a tip end portion (lower end portion) of the sleeve400. The sleeve-side connection part410has a cylindrical shape as a whole. The sleeve-side connection part410has an engagement recess412. The engagement recess412is provided on an outer circumferential surface of the sleeve-side connection part410. The engagement recess412is a circumferential groove.

As shown inFIG. 3, the spacer500has an inner surface502and an outer surface504. The inner surface502forms a sleeve hole. The sectional shape of the inner surface502corresponds to the sectional shape of the outer surface404of the sleeve400. The outer surface404of the sleeve400is fitted to the inner surface502. In other words, the sleeve400is fitted inside the spacer500. The spacer500is not bonded to the sleeve400. The spacer500merely abuts on the sleeve400.

The shape of the inner surface502corresponds to the shape of the outer surface404of the sleeve400. The inner surface502is a pyramid surface. The inner surface502is a four-sided pyramid surface. The sectional shape of the inner surface502is a non-circle. The sectional shape of the inner surface502is a polygon (regular polygon). The sectional shape of the inner surface502is a tetragon. The sectional shape of the inner surface502is a square. The area of a figure formed by a sectional line of the inner surface502is increased toward the tip side of the shaft300.

The shape of the outer surface504(outer surface of the tip engagement part RT) corresponds to the shape of the reverse-tapered hole206. The outer surface504is a pyramid surface. The outer surface504is a four-sided pyramid surface. The sectional shape of the outer surface504is a non-circle. The sectional shape of the outer surface504is a polygon (regular polygon). The sectional shape of the outer surface504is a tetragon. The sectional shape of the outer surface504is a square. The area of a figure formed by a sectional line of the outer surface504is increased toward the tip side of the shaft300. That is, the spacer500has a reverse-tapered shape. The sleeve400and the spacer500constitute the tip engagement part RT.

The golf club100has a screw member600. The screw member600has a screw-side connection part602and a male screw part604. The screw-side connection part602is positioned on the sleeve side (upper side) of the male screw part604. The male screw part604constitutes a rear end portion (lower end portion) of the screw member600. The screw-side connection part602can be detachably connected to the sleeve-side connection part410. As a result, the screw member600can be detachably connected to the sleeve400. The connection between the sleeve400and the screw member600can be easily made. The connection can be achieved by simply pressing the screw member600against the sleeve400. In other words, the screw member600can be connected to the sleeve400by a one-touch operation. The connection is automatically completed by simply inserting the sleeve-side connection part410to the screw-side connection part602. In addition, the connection can be easily released. The screw member600can also be easily removed from the sleeve400. The details of the connecting mechanism between the sleeve400and the screw member600will be described later.

FIG. 4shows a procedure of mounting the shaft300to the head200.

In the mounting procedure, an intermediate body350is first prepared (step (a) inFIG. 4). The intermediate body350has a shaft300and a sleeve400. In the intermediate body350, the sleeve400is fixed (bonded) to the tip end portion of the shaft300.

Next, the sleeve400of the intermediate body350is made to pass through the hosel hole204(step (b) inFIG. 4). The sleeve400is made to completely pass through the hosel hole204. The sleeve400is inserted to the hosel hole204from the upper side and is made to come out from the lower side of the hosel hole204. The sleeve400is moved to a lower side of the sole210by the passing (step (b) inFIG. 4).

Next, the spacer500is attached to the sleeve400(step (b) inFIG. 4). The spacer500is attached to the sleeve400in a state where the sleeve400has passed through the hosel hole204. The spacer500is externally attached to the sleeve400. The spacer500is attached to externally cover the sleeve400. The tip engagement part RT is completed by attaching the spacer500to the sleeve400. As described later, the spacer500has a divided structure. This divided structure makes it possible to attach the spacer500externally to the sleeve400.

Next, the intermediate member350is moved to the upper side with respect to the head200, whereby the tip engagement part RT (spacer500) is fitted to the reverse-tapered hole206(step (c) inFIG. 4). As a result, the shaft300is attached to the head200. The mounting of the shaft300to the head200is achieved by the fitting. In other words, an engagement state is achieved by the fitting. The engagement state is a state where the shaft300is fixed to the head200. In the engagement state, the golf club100can be used. In the engagement state, all reverse-tapered fittings are achieved. All reverse-tapered fittings mean: a fitting between the outer surface404and the inner surface502; and a fitting between the outer surface504and the reverse-tapered hole206.

Next, the screw member600is attached to a head200(step (d) inFIG. 4). The screw member600is attached to the head200from the lower side. The screw member600is rotated in a first direction, and is screwed into a female screw part of the head200. For the rotation, a tool such as a wrench may be used. The first direction is a direction in which the screw member600is fastened. As the screw-connection progresses, the screw member600is moved to a direction (the upper side) approaching the hosel hole204. With this movement, the screw member600presses the tip engagement part RT in an engaging direction (to the upper side). The pressing ensures the above-described engagement state. The pressing makes it possible to eliminate backlash.

The screw member600has a rotating engagement part606for engaging the tool (seeFIG. 2). The rotating engagement part606is a non-circular hole.

Thus, the shaft300is easily attached to the head200.

As described above, the screw member600presses the tip engagement part RT. Simultaneously with the pressing, the screw member600is connected to the sleeve400. When the screw member600is moved toward the tip engagement part RT, the sleeve-side connection part410is inserted to the screw-side connection part602of the screw member600. By this insertion, the sleeve-side connection part410is automatically connected to the screw-side connection part602. As a result, the sleeve400is connected to the screw member600.

The connection between the sleeve400and the screw member600facilitates the removal of the shaft300. To detach the shaft300from the head200, the above-described procedure is performed in the reverse order. In the reverse procedure, first, the screw member600is rotated in a second direction. The second direction is a direction opposite to the first direction. The second direction is a direction in which the screw member600is loosened. By this rotation, the screw member600is moved to the lower side. The screw member600is moved in a direction away from the hosel hole204. At this time, the connection between the sleeve400and the screw member600is maintained. While maintaining the connection between the sleeve400and the screw member600, the screw member600is rotated in the second direction. By this movement, the screw member600pulls the tip engagement part RT in an engagement releasing direction. The tip engagement part RT is pulled out from the hosel hole204by the screw member600.

Thus, the shaft300can also be removed from the head200easily.

As described above, in the golf club100, the shaft300is detachably attached to the head200. The shaft300can be removed and attached easily.

FIG. 5is a sectional view of the golf club100taken along the axial direction.FIG. 5is an enlarged sectional view of the vicinity of the tip engagement part RT.FIG. 6is a sectional view taken along line A-A inFIG. 5. InFIG. 6, the hatching is omitted.

As shown inFIG. 5, the head200has a female screw part220. The female screw part220is coaxial with the reverse-tapered hole206. That is, the center line of the female screw part220coincides with a center line Z6of the reverse-tapered hole206. The male screw part604of the screw member600is screw-connected to the female screw part220. The details of the screw-connection will be described later.

As described above, in order to press the sleeve400in the engaging direction by the screw member600, the screw member600is rotated in a first direction DR1, whereby the screw member600is screwed into the female screw part220(seeFIG. 5). In contrast, in order to pull the sleeve400in the engagement releasing direction by the screw member600, the screw member600is rotated in a second direction DR2.

In the present embodiment, a center line Z1of the inner surface402of the sleeve400is not inclined with respect to a center line Z2of the outer surface404of the sleeve400. The center line Z1conforms to the center line Z2. A center line Z3of the shaft300is not inclined with respect to the center line Z2of the outer surface404of the sleeve400. The center line Z3conforms to the center line Z2. A center line Z4of the inner surface502of the spacer500is not inclined with respect to a center line Z5of the outer surface504of the spacer500. The center line Z4conforms to the center line Z5. The center line Z4of the inner surface502of the spacer500is not inclined with respect to a center line Z6of the reverse-tapered hole206of the head200. The center line Z4conforms to the center line Z6. The center line Z3of the shaft300is not inclined with respect to the center line Z6of the reverse-tapered hole206of the head200. The center line Z3conforms to the center line Z6.

A double-pointed arrow D1inFIG. 5shows the minimum width of the hosel hole204. In the present embodiment, the sectional shape of the hosel hole204is a square, and the minimum width D1is the length of one side of the square at the upper end surface of the hosel hole204.

A double-pointed arrow D2inFIG. 5shows the maximum width of the sleeve400. In the present embodiment, the sectional shape of the outer surface404of the sleeve400is a square, and the maximum width D2is the length of one side of the square at the lower end surface of the sleeve400.

In the present embodiment, the minimum width D1is larger than the maximum width D2. In other words, the minimum value of the sectional area of the hosel hole204is larger than the maximum value of the sectional area of the sleeve400. The lower end of the sleeve400can pass through an opening of the upper end of the hosel hole204. As a result, the sleeve400can pass through the hosel hole204. The sleeve400can be inserted to the hosel hole204from the upper side, pass through the hosel hole204, and come out from the lower side of the hosel hole204. The thickness of the spacer500is set such that the minimum width D1is larger than the maximum width D2.

FIG. 7is a sectional view of a head having a tip engagement part RTa according to a modification example.FIG. 7is a sectional view corresponding toFIG. 6. InFIG. 7, the hatching is also omitted. The tip engagement part RTa has a sleeve400aand a spacer500a. The sleeve400aand the spacer500aconstitute the tip engagement part RTa.

The sleeve400ahas an inner surface402aand an outer surface404a. The inner surface402aforms a shaft hole. The sectional shape of the inner surface402ais a circle. The shape of the inner surface402acorresponds to the shape of the outer surface of the shaft300. The inner surface402ais fixed to the tip end portion of the shaft300. That is, the sleeve400ais fixed to the tip end portion of the shaft300. An adhesive is used for the fixation.

The outer surface404ais a pyramid surface. The outer surface404ais an eight-sided pyramid surface. The sectional shape of the outer surface404ais a non-circle. The sectional shape of the outer surface404ais a polygon (regular polygon). The sectional shape of the outer surface404ais an octagon. The sectional shape of the outer surface404ais a regular octagon. The area of a figure formed by a sectional line of the outer surface404ais increased toward the tip side of the shaft300. That is, the sleeve400ahas a reverse-tapered shape.

The spacer500ahas an inner surface502aand an outer surface504a. The inner surface502aforms a sleeve hole. The sectional shape of the inner surface502acorresponds to the sectional shape of the outer surface404aof the sleeve400a. The outer surface404aof the sleeve400ais fitted to the inner surface502a. In other words, the sleeve400ais fitted inside the spacer500a. The spacer500ais not bonded to the sleeve400a. The spacer500ais merely brought into contact with the sleeve400a.

The shape of the inner surface502acorresponds to the shape of the outer surface404aof the sleeve400a. The inner surface502ais a pyramid surface. The inner surface502ais an eight-sided pyramid surface. The sectional shape of the inner surface502ais a non-circle. The sectional shape of the inner surface502ais a polygon (regular polygon). The sectional shape of the inner surface502ais an octagon. The sectional shape of the inner surface502ais a regular octagon. The area of a figure formed by a sectional line of the inner surface502ais increased toward the tip side of the shaft300.

The shape of the outer surface504a(outer surface of the tip engagement part RTa) corresponds to the shape of a reverse-tapered hole. The outer surface504ais a pyramid surface. The outer surface504ais an eight-sided pyramid surface. The sectional shape of the outer surface504ais a non-circle. The sectional shape of the outer surface504ais a polygon (regular polygon). The sectional shape of the outer surface504ais an octagon. The sectional shape of the outer surface504ais a regular octagon. The area of a figure formed by a sectional line of the outer surface504ais increased toward the tip side of the shaft300.

FIG. 8is a perspective view of the spacer500.FIG. 9(a)is a sectional view taken along line A-A inFIG. 8. As described above, the spacer500has the inner surface502and the outer surface504.

The spacer500has a divided structure. The spacer500has a first divided body510and a second divided body520. A divisional line d1is shown inFIG. 8. The divisional line d1is a boundary between the first divided body510and the second divided body520.

The spacer500has a connecting part530, although not shown in the drawings exceptFIG. 8. In the present embodiment, the connecting part530is a plate spring. The plate spring is an elastic body. In the present embodiment, two connecting parts530are provided. One side of each of the connecting parts530is fixed to the first divided body510, and the other side of each of the connecting parts530is fixed to the second divided body520.

The connecting parts530are housed in respective recessed parts provided on the outer surface504. The connecting parts530are not projected outside the outer surface504. The connecting parts530do not hamper contact between the reverse-tapered hole206and the outer surface504.

Although the step (b) inFIG. 4shows that the first divided body510and the second divided body520are separated from each other, the spacer500is actually configured to open and close. The connecting parts530play the role of a hinge. The spacer500opens on the connecting parts530. The spacer500opens by applying an external force. This opened state is shown by two-dot chain lines inFIG. 9(a). The spacer500opens by bending the connecting parts530(plate springs). In this opened state, a gap gp is produced between the first divided body510and the second divided body520. The sleeve400can be put inside the spacer500through the gap gp. The spacer500is closed in a state where the sleeve400is put inside the spacer. The plate springs530bias the spacer500so that the spacer500is in a closed state. Therefore, the spacer500is (automatically) closed if the external force is lost.

The connecting parts530can maintain a connected state in which the first divided body510is connected to the second divided body520. The spacer500is in the connected state when an external force does not act on the spacer500. The connected state is a state of the spacer500in the golf club100usable as a club.

The spacer500has a position adjusting structure to prevent a positional displacement between the first divided body510and the second divided body520. As the position adjusting structure, a plate splicing structure may be applied. The embodiment ofFIG. 9(a)includes an example of the position adjusting structure. In the position adjusting structure, the first divided body510has an abutting surface m1which prevents the positional displacement in a thickness direction, and an abutting surface m2which prevents the positional displacement in an axial direction. Similarly, the second divided body520has the abutting surface m1which prevents the positional displacement in the thickness direction, and the abutting surface m2which prevents the positional displacement in the axial direction. In the spacer500in the closed state, the abutting surface m1of the first divided body510abuts on the abutting surface m1of the second divided body520, and the abutting surface m2of the first divided body510abuts on the abutting surface m2of the second divided body520. Therefore, the positional displacements in the thickness direction and the axial direction are prevented.

The spacer500can fulfill the function thereof even if the spacer500does not have the position adjusting structure because the spacer500is fitted to the outer surface of the sleeve, the inner surface of the hosel hole, etc. In comparison between the abutting surfaces m1and the abutting surfaces m2, the abutting surfaces m2which prevent the positional displacement in the axial direction is more effective. This is because the spacer500is fitted to the outer surface of the sleeve, the inner surface of the hosel hole, etc., and thus the positional displacement in the thickness direction is less likely to occur. In this respect, the position adjusting structure preferably includes the abutting surfaces m2which prevent the positional displacement in the axial direction, and more preferably includes the abutting surfaces m2which prevent the positional displacement in the axial direction, and the abutting surfaces m1which prevent the positional displacement in the thickness direction.

As shown inFIG. 9(a), the divisional line d1of the spacer500includes a first divisional line d11and a second divisional line d12. The first divisional line d11is a divisional line on which the connecting parts530are not present. The second divisional line d12is a divisional line on which the connecting parts530are present. InFIG. 9(a), the above-described position adjusting structure provided on the first divisional line d11is shown. Preferably, the position adjusting structure is provided also on the second divisional line d12.

FIG. 9(b)shows another position adjusting structure. In this position adjusting structure, a projection of a first member Pt1and a recess of a second member Pt2are butted against each other. The center side in a thickness direction of the first member Pt1is overlapped with an inner side and an outer side in a thickness direction of the second member Pt2. The first member Pt1is either one of the first divided body510and the second divided body520. The second member Pt2is the other of the first divided body510and the second divided body520.

FIG. 9(c)shows another position adjusting structure. In this position adjusting structure, a projection of a first member Pt1and a recess of a second member Pt2are butted against each other. The section of the projection of the first member Pt1is constituted by slopes. The section of the recess of the second member Pt2is constituted by slopes. The center side in a thickness direction of the first member Pt1is overlapped with an inner side and an outer side in a thickness direction of the second member Pt2. The first member Pt1is either one of the first divided body510and the second divided body520. The second member Pt2is the other of the first divided body510and the second divided body520.

The position adjusting structures shown inFIG. 9(b)andFIG. 9(c)can also prevent the positional displacement in the axial direction in addition to the positional displacement in the thickness direction. For example, when such a position adjusting structure as shown inFIG. 9(b)orFIG. 9(c)is adopted only at a part of the axial direction, an abutting surface capable of preventing the positional displacement in the axial direction can be formed at a termination position of the position adjusting structure. Therefore, the positional displacement in the axial direction can be prevented.

FIG. 10is a perspective view of a spacer700according to another modification example. The spacer700has an inner surface702and an outer surface704.

The spacer700has a divided structure. The spacer700has a first divided body710and a second divided body720. A divisional line d1is shown inFIG. 10. The divisional line d1is a boundary between the first divided body710and the second divided body720.

The spacer700has ring-shaped elastic bodies730and740. The spacer700further has circumferential grooves750and760. The elastic bodies730and740are fitted to the circumferential grooves750and760, respectively. The elastic bodies730and740are not projected outside the outer surface704. The elastic bodies730and740do not hamper contact between the outer surface704and a reverse-tapered surface to which the outer surface704is fitted. The reverse-tapered surface to which the outer surface704is fitted is the reverse-tapered hole of the head or an inner surface of another spacer. The elastic bodies730and740are an example of a connecting part capable of maintaining a connected state in which the first divided body710and the second divided body720are connected to each other.

The elastic bodies730and740can be removed by applying an external force to stretch the elastic bodies730and740. The first divided body710and the second divided body720can be separated from each other by removing the elastic bodies730and740. On the contrary, the elastic bodies730and740can be attached after butting the first divided body710and the second divided body720against each other. The elastically contractile force of the elastic bodies730and740biases the divided bodies710and720so that the two divided bodies710and720are abutted against each other. For example, this spacer700also enables to replace a spacer.

Thus, the spacer500and the spacer700each have the divided structure. The spacer500and the spacer700each have the first divided body and the second divided body. The spacer500and the spacer700each have the connecting part capable of maintaining the connected state in which the first divided body is connected to the second divided body. In the spacer500and the spacer700, the mutual transition between the connected state in which the first divided body and the second divided body are connected to each other, and a separated state in which a gap is formed between the first divided body and the second divided body is enabled. In the separated state, the sleeve can be disposed inside the spacer by allowing the sleeve to pass through the gap. In the separated state, the spacer can be detached from or attached to the shaft300to which the sleeve400is fixed.

FIG. 11is a sectional view of a golf club100baccording to another embodiment.FIG. 11is an enlarged sectional view of the vicinity of a tip engagement part RTb.

In the present embodiment, a center line Z1of an inner surface402bof a sleeve400bis inclined with respect to a center line Z2of an outer surface404bof the sleeve400b. The inclination angle is θ degree. The center line Z3of the shaft300is inclined with respect to the center line Z2of the outer surface404bof the sleeve400b. The inclination angle is θ degree. A center line Z4of an inner surface502bof a spacer500bis not inclined with respect to a center line Z5of an outer surface504bof the spacer500b. The center line Z4conforms to the center line Z5. The center line Z4of the inner surface502bof the spacer500bis not inclined with respect to a center line Z6of a reverse-tapered hole206bof a head200b. The center line Z4conforms to the center line Z6. The center line Z3of the shaft300is inclined with respect to the center line Z6of the reverse-tapered hole206b. The inclination angle is θ degree.

Thus, in the embodiment ofFIG. 11, the center line Z1of the inner surface402bof the sleeve400bis inclined with respect to the center line Z6of the reverse-tapered hole206b. Therefore, a loft angle and a lie angle can be changed based on a rotation position of the sleeve400b. The embodiment ofFIG. 11has an angle adjusting function.

The center line Z4of the inner surface502bof the spacer500bmay be inclined with respect to the center line Z5of the outer surface504bof the spacer500b. The inclination between the center line Z1of the inner surface402bof the sleeve400band the center line Z2of the outer surface404bis defined as an inclination A, and the inclination between the center line Z4of the inner surface502bof the spacer500band the center line Z5of the outer surface504bis defined as an inclination B. The inclination A and the inclination B may be used alone or in combination. This combination enhances the degree of freedom of angle adjustment.

Although not shown in the drawings, the sleeve400balso has a sleeve-side connection part. In the present embodiment, the position of the sleeve-side connection part changes because of the inclination. To address the change, a sleeve including an adjustment mechanism in which the sleeve-side connection part is movable with respect to the sleeve body may be used, for example. Such a sleeve will be described later.

[Rotation Position of Sleeve]

The sleeve can be rotated about the center line of the sleeve itself. The rotation position of the sleeve is changed by the rotation. In the engagement state, the sleeve can take a plurality of rotation positions. The number of the rotation positions which can be taken is set based on the shape of the outer surface of the sleeve.

[Rotation Position of Spacer]

The spacer can be rotated about the center line of the spacer itself. The rotation position of the spacer is changed by the rotation. In the engagement state, the spacer can take a plurality of rotation positions. The number of the rotation positions which can be taken is set based on the shape of the outer surface of the spacer.

[Adjustment of Position and Direction of Center Line of Shaft]

The center line of the shaft hole (the center line of the shaft) can be displaced with respect to the center line of the outer surface of the sleeve. These center lines may be inclined with respect to each other, or may be displaced in parallel to each other (parallel and eccentric). Inclination and eccentricity may be combined. In this case, the direction and/or the position of the center line of the shaft can be changed by the rotation position of the sleeve.

The center line of the inner surface of the spacer can be displaced with respect to the center line of the outer surface of the spacer. These center lines may be inclined with respect to each other, or may be displaced in parallel to each other (parallel and eccentric). Inclination and eccentricity may be combined. In this case, the direction and/or the position of the center line of the shaft can be changed by the rotation position of the spacer.

The rotation position of the spacer can be selected independently of the rotation position of the sleeve. In addition, when a plurality of spacers are used, rotation positions of the respective spacers can be selected independently of each other. The degree of freedom of the adjustment is enhanced by the spacer. The degree of freedom of the adjustment is further enhanced by using a plurality of spacers. In these respects, the number of the spacers which are stacked is preferably one or two or more. In view of complexity of adjustment and downsizing of the hosel part, the number of the spacers which are stacked is preferably one or two.

FIG. 12toFIG. 17are plan views showing the position of a lower end surface of the tip engagement part. The illustration of the sleeve-side connection part is omitted in these plan views. Changes in the position and the direction of the center line of the shaft will be explained using these plan views.

InFIG. 12toFIG. 17, the following abbreviations are used.LI: lie angleLF: loft angleFP: face progressionDC: distance of the center of gravityL: largeM: mediumS: small

FIG. 12toFIG. 15show an embodiment A in which the number of the spacers is one. In this embodiment, a sleeve sv1and a spacer sp1are used. A position Zs of the center line of the shaft at the lower end of the hosel hole is shown by the intersection point of solid lines. The intersection point of one-dot chain lines shows a position of the center line of the shaft at the upper end of the hosel hole. In this embodiment, the position of the center line of the shaft at the upper end of the hosel hole is not changed regardless of the rotation positions of the sleeve sv1and the spacer sp1.

The embodiment A shown inFIG. 12toFIG. 15satisfies the following (A1) and (A2).

(A1) A center line of an inner surface of the sleeve sv1(that is, the center line of the shaft) is inclined with respect to a center line of an outer surface of the sleeve sv1.

(A2) A center line of an inner surface of the spacer sp1is inclined with respect to a center line of an outer surface of the spacer sp1.

In the embodiment A, the outer surface of the sleeve sv1is a four-sided pyramid surface, each of the inner surface and the outer surface of the spacer sp1is also a four-sided pyramid surface, and a reverse-tapered hole is also a four-sided pyramid surface. Therefore, the number of the rotation positions of the sleeve sv1is four, and the number of the rotation positions of the spacer sp1is also four. In the embodiment A, the number of kinds of combinations of the rotation positions of the sleeve sv1and the rotation positions of the spacer sp1is: 4×4=16. A golf club according to the embodiment A is excellent in degree of freedom of adjustment.FIG. 12toFIG. 15show all the 16 kinds of combinations.

In state (a) ofFIG. 12, the rotation position of the sleeve sv1is a first position, and the rotation position of the spacer sp1is a first position. In state (b) ofFIG. 12, the rotation position of the sleeve sv1is a second position, and the rotation position of the spacer sp1is the first position. In state (c) ofFIG. 12, the rotation position of the sleeve sv1is a third position, and the rotation position of the spacer sp1is the first position. In state (d) ofFIG. 12, the rotation position of the sleeve sv1is a fourth position, and the rotation position of the spacer sp1is the first position.

In state (a) ofFIG. 13, the rotation position of the sleeve sv1is the first position, and the rotation position of the spacer sp1is a second position. In state (b) ofFIG. 13, the rotation position of the sleeve sv1is the second position, and the rotation position of the spacer sp1is a second position. In state (c) ofFIG. 13, the rotation position of the sleeve sv1is the third position, and the rotation position of the spacer sp1is the second position. In state (d) ofFIG. 13, the rotation position of the sleeve sv1is the fourth position, and the rotation position of the spacer sp1is the second position.

In state (a) ofFIG. 14, the rotation position of the sleeve sv1is the first position, and the rotation position of the spacer sp1is a third position. In state (b) ofFIG. 14, the rotation position of the sleeve sv1is the second position, and the rotation position of the spacer sp1is the third position. In state (c) ofFIG. 14, the rotation position of the sleeve sv1is the third position, and the rotation position of the spacer sp1is the third position. In state (d) ofFIG. 14, the rotation position of the sleeve sv1is the fourth position, and the rotation position of the spacer sp1is the third position.

In state (a) ofFIG. 15, the rotation position of the sleeve sv1is the first position, and the rotation position of the spacer sp1is a fourth position. In state (b) ofFIG. 15, the rotation position of the sleeve sv1is the second position, and the rotation position of the spacer sp1is the fourth position. In state (c) ofFIG. 15, the rotation position of the sleeve sv1is the third position, and the rotation position of the spacer sp1is the fourth position. In state (d) ofFIG. 15, the rotation position of the sleeve sv1is the fourth position, and the rotation position of the spacer sp1is the fourth position.

These 16 kinds of combinations include 9 kinds of positions Zs. That is, the center line of the shaft can take nine different positions.

InFIG. 12toFIG. 15, the transverse direction of the drawing is a face-back direction. The right side of the drawing is a face side, and the left side of the drawing is a back side. As the position Zs is closer to the rightmost side, the loft angle is smaller. As the position Zs is closer to the leftmost side, the loft angle is larger. The golf club according to the present embodiment is right-handed.

InFIGS. 12 to 15, the lengthwise direction of the drawing is a toe-heel direction. The upper side of the drawing is a toe side, and the lower side of the drawing is a heel side. As the position Zs is closer to the uppermost side, the lie angle is smaller. As the position Zs is closer to the lowermost side, the lie angle is larger.

According to the 9 kinds of positions of the center line of the shaft, specifications of the combinations of the loft angles and the lie angles are the following 9 kinds.

(Specification 1) The lie angle is small and the loft angle is small.

(Specification 2) The lie angle is small and the loft angle is medium.

(Specification 3) The lie angle is small and the loft angle is large.

(Specification 4) The lie angle is medium and the loft angle is small.

(Specification 5) The lie angle is medium and the loft angle is medium.

(Specification 6) The lie angle is medium and the loft angle is large.

(Specification 7) The lie angle is large and the loft angle is small.

(Specification 8) The lie angle is large and the loft angle is medium.

(Specification 9) The lie angle is large and the loft angle is large.

In the golf club according to the embodiment A, an independent variability of the loft angle is achieved. In the golf club according to the embodiment A, an independent variability of the lie angle is achieved. In the embodiment A, the direction (phase) of the reverse-tapered hole (hosel hole) is set so that the independent variability of the loft angle and the independent variability of the lie angle are achieved.

For example, among the specifications 1, 2, and 3, the loft angle is changed without changing the lie angle. This is one example of the independent variability of the loft angle. The same independent variability is provided also among the specifications 4, 5, and 6. The same independent variability is provided also among the specifications 7, 8, and 9.

For example, among the specifications 1, 4, and 7, the lie angle is changed without changing the loft angle. This is one example of the independent variability of the lie angle. The same independent variability is provided also among the specifications 2, 5, and 8. The same independent variability is provided also among the specifications 3, 6, and 9.

The independent variability of the loft angle means that the loft angle is changed without substantially changing the lie angle. The phrase “without substantially changing” means that change in the lie angle is equal to or less than 20% based on the amount of change in the loft angle. The independent variability of the lie angle means that the lie angle is changed without substantially changing the loft angle. The phrase “without substantially changing” means that change in the loft angle is equal to or less than 20% based on the amount of change in the lie angle.

FIG. 16andFIG. 17show an embodiment B in which the number of the spacers is 2 (double-layered). In the present embodiment, a sleeve sv1, a first spacer sp1, and a second spacer sp2are used. A position Zs of the center line of the shaft at the lower end of the hosel hole is shown by the intersection point of thick solid lines. The intersection point of one-dot chain lines shows the position of the center line of the outer surface of the sleeve sv1at the lower end of the hosel hole. The intersection point of thin solid lines shows the position of the center line of the outer surface of the spacer sp1at the lower end of the hosel hole. The intersection point of dashed lines shows the position of the center line of the outer surface of the spacer sp2at the lower end of the hosel hole. Regardless of the rotation positions of the sleeve sv1, the spacer sp1, and the spacer sp2, the three center lines cross at one point at the position of the upper end of the hosel hole.

In the embodiment B, the outer surface of the sleeve sv1is a four-sided pyramid surface. Each of inner and outer surfaces of the first spacer sp1is also a four-sided pyramid surface, and each of inner and outer surfaces of the second spacer sp2is also a four-sided pyramid surface. A reverse-tapered hole is also a four-sided pyramid surface. Therefore, the number of the rotation positions of the sleeve sv1is four, the number of the rotation positions of the first spacer sp1is also four, and the number of the rotation positions of the second spacer sp2is also four. In the embodiment B, the number of kinds of combinations of the three members' rotation positions is 4×4×4=64. A golf club according to the embodiment B has an excellent degree of freedom of adjustment.

The embodiment B shown inFIG. 16andFIG. 17satisfies the following (B1) to (B3).

(B1) A center line of an inner surface of the sleeve sv1(that is, the center line of the shaft) is parallel and eccentric to a center line of the outer surface of the sleeve sv1.

(B2) A center line of the inner surface of the first spacer sp1is inclined with respect to a center line of the outer surface of the first spacer sp1.

(B3) A center line of the inner surface of the second spacer sp2is inclined with respect to a center line of the outer surface of the second spacer sp2.

The phrase “parallel and eccentric” means eccentricity in which center lines are parallel to each other.

The relation between the first spacer sp1and the second spacer sp2in the embodiment B is the same as the relation between the sleeve sv1and the spacer sp1in the above-mentioned embodiment A. Therefore, 9 kinds of combinations of the loft angles and the lie angles are achieved by the first spacer sp1and the second spacer sp2. Furthermore, in the embodiment B, adjustment because of the sleeve sv1is added. Since the sleeve sv1is parallel and eccentric, each of the nine positions of the shaft axis can be further moved in parallel. The parallel movement of the shaft axis can change face progression. The parallel movement can achieve the movement of the shaft axis in the face-back direction. Furthermore, the parallel movement can achieve the movement of the shaft axis in the toe-heel direction. In the embodiment B, the degree of freedom of adjustment of the shaft axis is further improved by the two spacers.

In states (a) to (d) inFIG. 16, the rotation position of the first spacer sp1is a first position, and the rotation position of the second spacer sp2is also the first position. In states (a) to (d) inFIG. 16, only the rotation position of the sleeve sv1is changed without changing the rotation positions of the first spacer sp1and the second spacer sp2. In state (a) inFIG. 16, the rotation position of the sleeve sv1is a first position. In state (b) inFIG. 16, the rotation position of the sleeve sv1is a second position. In state (c) inFIG. 16, the rotation position of the sleeve sv1is a third position. In state (d) inFIG. 16, the rotation position of the sleeve sv1is a fourth position.

In states (a) to (d) inFIG. 17, the rotation position of the first spacer sp1is the second position, and the rotation position of the second spacer sp2is the first position. Also in states (a) to (d) inFIG. 17, only the rotation position of the sleeve sv1is changed without changing the rotation positions of the first spacer sp1and the second spacer sp2. In state (a) inFIG. 17, the rotation position of the sleeve sv1is the first position. In state (b) inFIG. 17, the rotation position of the sleeve sv1is the second position. In state (c) inFIG. 17, the rotation position of the sleeve sv1is the third position. In state (d) inFIG. 17, the rotation position of the sleeve sv1is the fourth position.

In comparingFIG. 16withFIG. 17, in states (a) to (d) inFIG. 16, the rotation position of the first spacer sp1is the first position, in contrast, in states (a) to (d) inFIG. 17, the rotation position of the first spacer sp1is the second position. Because of the difference, the loft angle in each of states (a) to (d) inFIG. 17is decreased to medium as compared with the large loft angle in each of states (a) to (d) inFIG. 16.

In states (a) to (d) inFIG. 16, the rotation position of the sleeve sv1changes from the first position to the fourth position. Because of the change, face progression (FP), which is an index showing the position of the center line of the shaft in the face-back direction, changes in order from large (L), medium (M), small (S), to medium (M). Simultaneously, the distance of the center of gravity which is an index showing the position of the center line of the shaft in the toe-heel direction changes in order from medium (M), small (S), medium (M), to large (L). The distance of the center of gravity is a distance between the center of gravity of the head and the center line of the shaft. The distance is measured in an image projected to a plane which is parallel to the toe-heel direction and includes the center line of the shaft.

Therefore, for example, in comparison between state (a) and state (c) inFIG. 16, the position of the center line of the shaft (the position of the center line of the shaft at the upper end of the hosel hole) moves in the face-back direction while maintaining the inclination of the center line of the shaft so that the lie angle is small and the loft angle is large. In addition, in state (a) and state (c) ofFIG. 16, the distance of the center of gravity is medium without change.

In comparison between state (b) and state (d) inFIG. 16, the position of the center line of the shaft (the position of the center line of the shaft at the upper end of the hosel hole) moves in the toe-heel direction while maintaining the inclination of the center line of the shaft so that the lie angle is small and the loft angle is large. In addition, in state (b) and state (d) ofFIG. 16, the face progression is medium without change.

Also in states (a) to (d) inFIG. 17, the rotation position of the sleeve sv1changes from the first position to the fourth position. Because of the change, the face progression changes in order from large, medium, small, to medium. Simultaneously, the distance of the center of gravity changes in order from medium, small, medium, to large.

Therefore, for example, in comparison between state (a) and state (c) inFIG. 17, the position of the center line of the shaft (the position of the center line of the shaft at the upper end of the hosel hole) moves in the face-back direction while maintaining the inclination of the center line of the shaft so that the lie angle is small and the loft angle is medium. In addition, in state (a) and state (c) ofFIG. 17, the distance of the center of gravity is medium without change.

In comparison between state (b) and state (d) inFIG. 17, the position of the center line of the shaft (the position of the center line of the shaft at the upper end of the hosel hole) moves in the toe-heel direction while maintaining the inclination of the center line of the shaft so that the lie angle is small and the loft angle is medium. In addition, in state (b) and state (d) ofFIG. 17, the face progression is medium without change.

Although the axis displacement of the sleeve sv1is parallel eccentricity in the present embodiment, the axis displacement may be naturally inclination, for example. Of course, parallel eccentricity may be adopted for the spacer.

As shown inFIG. 12toFIG. 17, the position of the center line of the shaft on the sole side can be variously changed. Since the present embodiment eliminates the need for screw fixation, the degrees of freedom of the position and the inclination of the center line of the shaft are high. Therefore, the range of angle adjustment can be increased. The range of adjustment for the loft angle, the lie angle, the face angle, the face progression, etc., can be increased.

Each of nine drawings shown inFIG. 18is a plan view (drawing viewed from above) of the sleeve which can be applied to the present embodiment. InFIG. 18, examples of the sectional shape of the outer surface of the sleeve include a tetragon (square), a hexagon (regular hexagon), and an octagon (regular octagon). Axis coincidence, axis parallel eccentricity, and axis inclination are shown as the form of the axis displacement of the sleeve inFIG. 18.

In a sleeve sv11, the sectional shape of the outer surface of the sleeve is tetragon (square); the outer surface of the sleeve is a four-sided pyramid surface; and the center line of the inner surface of the sleeve (the center line of the shaft) coincides with the center line of the outer surface of the sleeve. In a sleeve sv12, the sectional shape of the outer surface of the sleeve is a hexagon (regular hexagon); the outer surface of the sleeve is a six-sided pyramid surface; and the center line of the inner surface of the sleeve (the center line of the shaft) coincides with the center line of the outer surface of the sleeve. In a sleeve sv13, the sectional shape of the outer surface of the sleeve is an octagon (regular octagon); the outer surface of the sleeve is an eight-sided pyramid surface; and the center line of the inner surface of the sleeve (the center line of the shaft) coincides with the center line of the outer surface of the sleeve.

In a sleeve sv14, the sectional shape of the outer surface of the sleeve is a tetragon (square); the outer surface of the sleeve is a four-sided pyramid surface; and the center line of the inner surface of the sleeve (the center line of the shaft) is parallel and eccentric to the center line of the outer surface of the sleeve. In a sleeve sv15, the sectional shape of the outer surface of the sleeve is a hexagon (regular hexagon); the outer surface of the sleeve is a six-sided pyramid surface; and the center line of the inner surface of the sleeve (the center line of the shaft) is parallel and eccentric to the center line of the outer surface of the sleeve. In a sleeve sv16, the sectional shape of the outer surface of the sleeve is an octagon (regular octagon); the outer surface of the sleeve is an eight-sided pyramid surface; and the center line of the inner surface of the sleeve (the center line of the shaft) is parallel and eccentric to the center line of the outer surface of the sleeve.

In a sleeve sv17, the sectional shape of the outer surface of the sleeve is a tetragon (square); the outer surface of the sleeve is a four-sided pyramid surface; and the center line of the inner surface of the sleeve (the center line of the shaft) is inclined with respect to the center line of the outer surface of the sleeve. In a sleeve sv18, the sectional shape of the outer surface of the sleeve is a hexagon (regular hexagon); the outer surface of the sleeve is a six-sided pyramid surface; and the center line of the inner surface of the sleeve (the center line of the shaft) is inclined with respect to the center line of the outer surface of the sleeve. In a sleeve sv19, the sectional shape of the outer surface of the sleeve is an octagon (regular octagon); the outer surface of the sleeve is an eight-sided pyramid surface; and the center line of the inner surface of the sleeve (the center line of the shaft) is inclined with respect to the center line of the outer surface of the sleeve.

Thus, various sleeves may be used. Of course, these sleeves shown inFIG. 18are merely exemplified. Similarly, various forms may be adopted also for the spacer.

From the viewpoint of preventing an excessively large hosel, the amount of eccentricity of parallel eccentricity in the sleeve is preferably equal to or less than 5 mm, more preferably equal to or less than 2 mm, and still more preferably equal to or less than 1.5 mm. From the viewpoint of adjusting properties, the amount of eccentricity of parallel eccentricity in the sleeve is preferably equal to or greater than 0.5 mm, and more preferably equal to or greater than 1.0 mm.

From the viewpoint of preventing an excessively large hosel, the inclination angle θ1of the center line of the shaft with respect to the center line of the outer surface of the sleeve is preferably equal to or less than 5 degrees, more preferably equal to or less than 3 degrees, and still more preferably equal to or less than 2 degrees. From the viewpoint of adjusting properties, the inclination angle θ1is preferably equal to or greater than 0.5 degrees, more preferably equal to or greater than 1 degree, and still more preferably equal to or greater than 1.5 degrees.

From the viewpoint of preventing an excessively large hosel, the amount of eccentricity of parallel eccentricity in the spacer is preferably equal to or less than 5 mm, more preferably equal to or less than 2 mm, and still more preferably equal to or less than 1.5 mm. From the viewpoint of adjusting properties, the amount of eccentricity of parallel eccentricity in the spacer is preferably equal to or greater than 0.5 mm, and more preferably equal to or greater than 1.0 mm.

From the viewpoint of preventing an excessively large hosel, the inclination angle θ2of the center line of the inner surface of the spacer with respect to the center line of the outer surface of the spacer is preferably equal to or less than 5 degrees, more preferably equal to or less than 3 degrees, and still more preferably equal to or less than 2 degrees. From the viewpoint of adjusting properties, the inclination angle θ2is preferably equal to or greater than 0.5 degrees, more preferably equal to or greater than 1 degree, and still more preferably equal to or greater than 1.5 degrees.

An engagement releasing direction and an engaging direction are defined in the present application. In the present application, the engagement releasing direction is a direction in which the tip engagement part RT moves toward the sole side with respect to the reverse-tapered hole206. In other words, the engagement releasing direction means a direction in which the reverse-tapered hole206moves toward the grip side with respect to the tip engagement part RT. If the tip engagement part RT is moved in the engagement releasing direction, the tip engagement part RT comes out of the reverse-tapered hole206. On the other hand, the engaging direction in the present application means a direction in which the tip engagement part RT moves toward the grip side with respect to the reverse-tapered hole206. In other words, the engaging direction means a direction in which the reverse-tapered hole206moves toward the sole side with respect to the tip engagement part RT.

In the golf club in the engagement state, the reverse-tapered fitting is formed between the tip engagement part RT and the reverse-tapered hole206. A force in the engaging direction cannot release the reverse-tapered fitting, and on the contrary, enhances the contact pressure of the reverse-tapered fitting. The force in the engaging direction further ensures the engagement between the tip engagement part RT and the reverse-tapered hole206.

A large force acting on the head is a centrifugal force during swinging, and an impact shock force upon impact. Of the forces, the centrifugal force is the above-mentioned force in the engaging direction. Because of a loft angle of the head, a component force of the impact shock force in the axial direction is also the force in the engaging direction. Therefore, the centrifugal force and the impact shock force cannot release the engagement between the tip engagement part RT and the reverse-tapered hole206, and further ensures the engagement conversely. Since each of the tip engagement part RT and the reverse-tapered hole206has a non-circular sectional shape, relative rotation between the two cannot occur. As a result, although the tip engagement part RT and the reverse-tapered hole206are not fixed by an adhesive or the like, retention and anti-rotation required as a golf club are achieved. The structure of the reverse-tapered fitting can achieve both holding properties and attaching/detaching easiness.

Therefore, the screw member600is not necessarily needed.

However, the result of the studies made by the inventor has demonstrated the effectiveness of the screw member600. It has been found that high dimensional accuracy is required to bring the outer surface of the tip engagement part RT into complete surface-contact with the inner surface of the hosel hole204. It has been found that even a slight dimensional error could cause backlash. The backlash results in a sense of discomfort during hitting.

It has been found that as a result of the screw member600pressing the tip engagement part RT in the engaging direction, elastic deformation occurs in the tip engagement part RT and/or the hosel hole204, thus eliminating the backlash.

Furthermore, the inventor has found another effect of the screw member600. The tip engagement part RT pressed by the screw member600is firmly engaged with the hosel hole204with elastic deformation. It has been found that the tip engagement part RT that has been fitted with elastic deformation is less likely to come out from the hosel hole204. As described above, the sleeve400is connected to the screw member600, and therefore, moves together with the screw member600. When the screw member600is moved to the lower side as the screw-connection is released, the sleeve400is pulled to the lower side. As a result, by simply rotating the screw member600in the second direction DR2, the tip engagement part RT is pulled to the lower side, and is pulled out from the hosel hole204. Thus, the screw member600facilitates the removal of the shaft300.

In situations other than swinging, a force in the engagement releasing direction may act on the golf club. Examples of the situations include a state where the golf club is inserted into a golf bag. In this state, the golf club is stood with the head up. In this case, the gravity acting on the head acts as the force in the engagement releasing direction. The screw member600can prevent the falling-off of the head.

From the viewpoint of the Golf Rules, the screw member600is preferably configured so as not to be rotated by bare hands. From the viewpoint of the Golf Rules, it is preferable that a special tool is required for rotating the screw member600.

The golf club may be configured such that its club length can be adjusted. For example, a plurality of spacers having different wall thicknesses may be prepared. By replacing the spacer, the wall thickness of the spacer is changed, and the axial direction position of the tip engagement part RT is changed. Therefore, the club length can be adjusted. In this case, extending the axial installation range of the female screw part enables the screw member to follow the change of the axial direction position of the tip engagement part RT.

FIG. 19is sectional views of a golf club1600according to another embodiment. In the golf club1600, the club length can be changed without replacing a spacer.

FIG. 19shows two states of the golf club1600. A state (a) inFIG. 19shows a first state of the golf club1600. A state (b1) inFIG. 19shows a second state of the golf club1600. The club length of the golf club1600in the first state is shorter than the club length of the golf club1600in the second state. In the golf club1600, two kinds of length can be selected.

FIG. 20is sectional views at a tip engagement part RT of the golf club1600, which illustrates a length adjustment mechanism.

A state (a) inFIG. 20is a sectional view in the first state (short state). As shown in the state (a) ofFIG. 20, the tip engagement part RT of the golf club1600includes a sleeve1700and a spacer1800.

The sleeve1700has a sleeve-side connection part1710. The structure of the sleeve-side connection part1710is the same as that of the above-described sleeve-side connection part410. The sleeve1700is bonded to the tip end portion of the shaft300. In the golf club1600, the above-described screw member600is also used.

The spacer1800has a divided structure. The sleeve1700can be made to pass through a hosel hole (not shown in the drawing). The golf club1600can be assembled by the procedure shown inFIG. 4.

As shown inFIG. 19, the inner surface of the spacer1800has a first abutting face S1and the second abutting face S2.

A plurality of (four) first abutting faces S1are provided on the inner surface of the spacer1800. A plurality of (four) second abutting faces S2are provided on the inner surface of the spacer1800. The first abutting faces S1and the second abutting faces S2are alternately arranged. In the present embodiment, the number of the first abutting faces S1is four, and the number of the second abutting faces S2is four. The sum of the number of the first abutting faces S1and the number of the second abutting faces S2is eight.

As shown in the state (a) ofFIG. 19, the first abutting faces S1coincide with respective alternate sides of a regular polygon (regular octagon). The regular polygon (regular octagon) coinciding with the first abutting faces S1is defined as a first virtual regular polygon (not shown in the drawing). As shown in the state (a) inFIG. 19, the second abutting faces S2coincide with respective alternate sides of a regular polygon (regular octagon). The regular polygon (regular octagon) coinciding with the second abutting faces S2is defined as a second virtual regular polygon (not shown in the drawing).

A radial direction position of the second abutting faces S2is outside with respect to a radial direction position of the first abutting faces S1. The first virtual regular polygon (virtual regular octagon) is smaller than the second virtual regular polygon (virtual regular octagon). The first virtual regular polygon (virtual regular octagon) and the second virtual regular polygon (virtual regular octagon) have the common central point and the same phase.

Thus, the first abutting faces S1and the second abutting faces S2are alternately arranged along respective sides of a regular polygon (regular octagon), and the radial direction position of the first abutting faces S1is (slightly) inside of the radial direction position of the second abutting faces S2. A step surface S3is formed on each boundary between the first abutting faces S1and the second abutting faces S2. The step surface S3may not be present.

As shown in the state (a) inFIG. 19, the outer surface of the sleeve1700includes an abutting engagement face T1and a non-abutting engagement face T2.

A plurality of (four) abutting engagement faces T1are provided on the outer surface of the sleeve1700. A plurality of (four) non-abutting engagement faces T2are provided on the outer surface of the sleeve1700. The abutting engagement faces T1and the non-abutting engagement faces T2are alternately arranged. In the present embodiment, the number of the abutting engagement faces T1is four, and the number of the non-abutting engagement faces T2is four. The sum of the number of the abutting engagement faces T1and the number of the non-abutting engagement faces T2is eight.

As shown in the state (a) inFIG. 19, the abutting engagement faces T1coincide with respective alternate sides of a regular polygon (regular octagon). The regular polygon (regular octagon) coinciding with the abutting engagement faces T1is defined as a third virtual regular polygon (not shown in the drawing). As shown in the state (a) inFIG. 19, the non-abutting engagement faces T2coincide with respective alternate sides of a regular polygon (regular octagon). The regular polygon (regular octagon) coinciding with the non-abutting engagement faces T2is defined as a fourth virtual regular polygon (not shown in the drawing).

A radial direction position of the abutting engagement faces T1is outside with respect to a radial direction position of the non-abutting engagement faces T2. Therefore, the third virtual regular polygon (virtual regular octagon) is greater than the fourth virtual regular polygon (virtual regular octagon). The third virtual regular polygon (virtual regular octagon) and the fourth virtual regular polygon (virtual regular octagon) have the common central point and the same phase.

Thus, the abutting engagement faces T1and the non-abutting engagement faces T2are alternately arranged along respective sides of a regular polygon (regular octagon), and the radial direction position of the abutting engagement faces T1is (slightly) outside of the radial direction position of the non-abutting engagement faces T2. A step surface T3is formed on each boundary between the abutting engagement faces T1and the non-abutting engagement faces T2. The step surface T3may not be present.

The state (a) inFIG. 19is a sectional view in the first state (a state where the club length is short). In the first state, the sleeve1700is set on a first rotation position.

In the first state, the abutting engagement faces T1abut on the respective first abutting faces S1. In the first state, the abutting engagement faces T1are opposed to the respective first abutting faces S1, and the non-abutting engagement faces T2are opposed to the respective second abutting faces S2. While the abutting engagement faces T1abut on the respective first abutting faces S1, the non-abutting engagement faces T2do not abut on the respective second abutting faces S2. A gap is formed each between the non-abutting engagement faces T2and the respective second abutting faces S2.

A state (b1) inFIG. 19is a sectional view showing a shifting state for shifting to the second state. In the state (b1) ofFIG. 19, the sleeve1700is set on a second rotation position.

The shifting state for shifting to the second state means a state in which the sleeve1700is rotated by a predetermined angle θ (45 degrees) without changing the axial direction position of the sleeve1700with respect to the spacer1800. The shifting state is depicted in order to facilitate the understanding of the length adjustment mechanism. When the rotation of the predetermined angle θ is actually performed, the rotation can be made after once moving the tip engagement part RT in the engagement releasing direction. The rotation position of the sleeve1700is shifted to the second rotation position from the first rotation position by rotating the sleeve1700by the predetermined angle θ.

In the shifting state, the abutting engagement faces T1are opposed to the respective second abutting faces S2, and the non-abutting engagement faces T2are opposed to the respective first abutting faces S1. In this state, the abutting engagement faces T1do not abut on the respective second abutting faces S2. As a matter of course, the non-abutting engagement faces T2do not abut on the respective first abutting faces S1, either. A width of each gap gp between the abutting engagement face T1and the second abutting face S2is smaller than a width of each gap between the non-abutting engagement face T2and the first abutting face S1.

The fact that the abutting engagement faces T1do not abut on the respective second abutting faces S2in the state (b1) (shifting state) ofFIG. 19indicates the feasibility of two kinds of club lengths. That is, the gap gp realizes a second club length (greater club length). This point is explained below by usingFIG. 20.

A state (a) inFIG. 20is a sectional view taken along line A-A in the state (a) ofFIG. 19. A state (b1) inFIG. 20is a sectional view taken along line B-B in the state (b1) ofFIG. 19. As also shown in the state (b1) inFIG. 20, in the shifting state, a gap gp is present between the abutting engagement faces T1and the respective second abutting faces S2. For eliminating the gap to make the abutting engagement faces T1abut on the respective second abutting faces S2, the shaft300to which the sleeve1700is fixed should be moved to the axial-direction upper side. That is, the abutting engagement faces T1abut on the respective second abutting faces S2by moving the sleeve1700in the shifting state to the axial-direction upper side with respect to the spacer1800. As a result, the second state is realized. A state (b2) inFIG. 20shows the second state.

As described above, in the golf club1600, the axial direction position of the sleeve1700with respect to the spacer1800in the first state is different from that of the second state. The first state in which the club length is short and the second state in which the club length is long are realized by the difference. In the golf club1600, a mutual shifting between the first state and the second state is enabled by rotating the sleeve1700with respect to the spacer1800.

Extending the axial installation range of the female screw part enables the screw member to follow the change of the axial direction position of the sleeve-side connection part1710.

Thus, in the present embodiment, the sleeve1700having a reverse-tapered outer surface and the spacer1800having a reverse-tapered inner surface are used. Either one of the reverse-tapered outer surface and the reverse-tapered inner surface includes the abutting engagement faces T1. The other of the reverse-tapered outer surface and the reverse-tapered inner surface includes the first abutting faces S1and the second abutting faces S2. The first state in which the abutting engagement faces T1abut on the respective first abutting faces S1is formed when the reverse-tapered outer surface is set on the first rotation position. In addition, the second state in which the abutting engagement faces T1abut on the respective second abutting faces S2is formed when the reverse-tapered outer surface is set on the second rotation position. An axial direction position of the reverse-tapered outer surface with respect to the reverse-tapered inner surface in the first state is different from that of the second state, and a club length is adjusted by the difference. Preferably, the reverse-tapered outer surface includes the non-abutting engagement faces T2in addition to the abutting engagement faces T1. Preferably, the reverse-tapered outer surface is a pyramid outer surface, and the abutting engagement faces and the non-abutting engagement faces are alternately arranged on the pyramid outer surface. Preferably, the radial direction position of the abutting engagement faces is located outside with respect to the radial direction position of the non-abutting engagement faces. Preferably, the reverse-tapered inner surface may be a pyramid inner surface corresponding to the pyramid outer surface, and the first abutting faces and the second abutting faces are alternately arranged on the pyramid inner surface. Preferably, the pyramid outer surface is an eight-sided pyramid surface. Preferably, the pyramid inner surface is an eight-sided pyramid surface.

FIG. 21is a perspective view of a sleeve2000according to another embodiment.FIG. 22(a)is a plan view of the sleeve2000.FIG. 22(b)is a sectional view taken along line B-B inFIG. 21.FIG. 22(c)is a sectional view taken along line C-C inFIG. 21.FIG. 22(d)is a bottom view of the sleeve2000.

The sleeve2000has an inner surface2002, an outer surface2004, an upper end surface2006and a lower end surface2008. The inner surface2002is a circumferential surface. A shaft is bonded to the inner surface2002.

The sleeve2000further has a sleeve-side connection part2009. The configuration of the sleeve-side connection part2009is the same as that of the above-described sleeve-side connection part410.

In the present embodiment, the above-described screw member600is also used. The screw member600can be connected to the sleeve-side connection part2009.

The outer surface2004has reverse-tapered engagement faces K1. The reverse-tapered engagement faces K1are arranged at a plurality of positions in the circumferential direction. The reverse-tapered engagement faces K1are arranged at equal intervals in the circumferential direction. The reverse-tapered engagement faces K1are arranged at intervals of a predetermined angle (90 degree) in the circumferential direction.

The outer surface2004has non-engagement faces K2. The non-engagement faces K2are arranged at a plurality of positions in the circumferential direction. The non-engagement faces K2are arranged at equal intervals in the circumferential direction. The non-engagement faces K2are arranged at intervals of a predetermined angle (90 degree) in the circumferential direction.

The reverse-tapered engagement faces K1and the non-engagement faces K2are alternately arranged in the circumferential direction.

As understood fromFIG. 22(a)toFIG. 22(d), the sectional area of the outer surface2004is increased as going to the lower end surface2008from the upper end surface2006. In the sectional shape of the outer surface2004, the reverse-tapered engagement faces K1are shifted toward the radially outward direction as going to the lower side. As a result, the reverse-tapered engagement faces K1becomes reverse-tapered surfaces (seeFIG. 21).

The sectional shape of the non-engagement faces K2is the same regardless of the axial direction position thereof. The sectional shape of the non-engagement faces K2is along a polygon (regular polygon). The sectional shape of the non-engagement faces K2is along an octagon (regular octagon). The sectional shape of the non-engagement faces K2coincides with respective alternate sides of the regular polygon. The radial direction position of the non-engagement faces K2remains the same at any axial direction position. At any axial direction position, the reverse-tapered engagement faces K1are located outside of the non-engagement faces K2in the radial direction.

The sectional shape of the outer surface2004has a rotation symmetric property at any axial direction position. At any axial direction position, the sectional shape of the outer surface2004has 4-fold rotation symmetry. When the sectional shape of the outer surface2004has n-fold rotation symmetry (n is an integer of equal to or greater than 2), n is preferably equal to or greater than 3 and equal to or less than 12, and more preferably equal to or greater than 4 and equal to or less than 8. In the present application, n means the maximum value in values n can take. For example, a square has 4-fold rotation symmetry, and also has 2-fold rotation symmetry. However, n of the square is the maximum value in the values n can take, that is, 4.

FIG. 23(a)toFIG. 23(d)shows a hosel hole2010.FIG. 23(a)is a plan view of the hosel hole2010, and shows the upper end surface of the hosel hole2010.FIG. 23(d)is a bottom view of the hosel hole2010, and shows the lower end surface of the hosel hole2010.FIG. 23(b)andFIG. 23(c)are sectional views of the hosel hole2010.FIG. 23(b)is a sectional view of the hosel hole2010at a position corresponding to line B-B inFIG. 21.FIG. 23(c)is a sectional view of the hosel hole2010at a position corresponding to line C-C inFIG. 21.

The hosel hole2010corresponds to the sleeve2000. The sleeve2000is fixed to a tip end portion of a shaft (not shown in the drawings). The shaft to which the sleeve2000is fixed is fixed to the hosel hole2010of the head. The hosel hole2010is provided on a hosel part2012of the head.

The hosel hole2010has reverse-tapered hole faces J1. The reverse-tapered hole faces J1are faces corresponding to the respective reverse-tapered engagement faces K1. The reverse-tapered hole faces J1are arranged at a plurality of positions in the circumferential direction. The reverse-tapered hole faces J1are arranged at equal intervals in the circumferential direction. The reverse-tapered hole faces J1are arranged at intervals of a predetermined angle (90 degree) in the circumferential direction.

The hosel hole2010has interference-avoiding faces J2. The interference-avoiding faces J2are arranged at a plurality of positions in the circumferential direction. The interference-avoiding faces J2are arranged at equal intervals in the circumferential direction. The interference-avoiding faces J2are arranged at intervals of a predetermined angle (90 degree) in the circumferential direction.

The reverse-tapered hole faces J1and the interference-avoiding faces J2are alternately arranged in the circumferential direction.

As understood fromFIG. 23(a)toFIG. 23(d), the sectional area of the hosel hole2010is increased as going to the lower end surface from the upper end surface. In the sectional shape of the hose hole2010, the reverse-tapered hole faces J1are shifted toward the radially outward direction as going to the lower side. The reverse-tapered hole faces J1are reverse-tapered surfaces.

The radial direction position and orientation of the interference-avoiding faces J2are the same regardless of the axial direction position thereof. The sectional shape of the interference-avoiding faces J2is along a polygon (regular polygon). The sectional shape of the interference-avoiding faces J2is along an octagon (regular octagon). The sectional shape of the interference-avoiding faces J2coincide with respective alternate sides of the regular polygon. The radial direction position of the interference-avoiding faces J2remains the same at any axial direction position. At any axial direction position other than lower end surfaces of the interference-avoiding faces J2, the interference-avoiding faces J2are positioned outside of the reverse-tapered hole faces J1in the radial direction.

The sectional shape of the hosel hole2010has a rotation symmetric property at any axial direction position. At any axial direction position, the sectional shape of the hosel hole2010has 4-fold rotation symmetry. When the sectional shape of the hosel hole2010has n-fold rotation symmetry (n is an integer of equal to or greater than 2), n is preferably equal to or greater than 3 and equal to or less than 12, and more preferably equal to or greater than 4 and equal to or less than 8.

FIG. 24(a)andFIG. 24(b)each show the sleeve2000and the hosel hole2010in the engagement state.FIG. 24(a)is a plan view as viewed from the upper side, andFIG. 24(b)is a bottom view as viewed from the lower side.FIG. 25is a sectional view taken along line A-A inFIG. 24(a)andFIG. 24(b). The golf club according to the present embodiment becomes usable by the engagement state. In the bottom view inFIG. 24(b), the illustration of the sleeve-side connection part2009is omitted.

In the engagement state, the reverse-tapered engagement faces K1abut on the respective reverse-tapered hole faces J1. All the reverse-tapered engagement faces K1abut on the respective reverse-tapered hole faces J1. The reverse-tapered engagement faces K1are fitted to the reverse-tapered hole faces J1.

In the engagement state, the non-engagement faces K2are opposed to the respective interference-avoiding faces J2. All the non-engagement faces K2are opposed to the respective interference-avoiding faces J2. A gap (space) is present each between the non-engagement faces K2and the respective interference-avoiding faces J2.

FIG. 26is a plan view showing the sleeve2000and the hosel hole2010in a process of passing the sleeve2000through the hosel hole2010.FIG. 26shows a state at a starting time of the passing process.FIG. 26shows the upper end surface of the hosel hole2010(FIG. 23(a)) and the lower end surface2008of the sleeve2000.

In the present embodiment, a spacer is not used. In the present embodiment, only the sleeve2000constitutes the tip engagement part RT.

As explained inFIG. 26, the tip engagement part RT can be made to pass through the hosel hole2010.FIG. 26shows the fact that the passing can be performed. The sleeve2000has the maximum sectional area at the lower end surface2008thereof. On the other hand, the hosel hole2010has the minimum sectional area at the upper end thereof.FIG. 26shows that the lower end surface2008having the maximum sectional area can pass through the upper end of the hosel hole2010which has the minimum sectional area. The sleeve2000can pass through the hosel hole2010. The sleeve2000can be inserted to the hosel hole2010from the upper side and can come out from the lower side of the hosel hole2010.

In the present application, a first phase state PH1and a second phase state PH2are defined. The first phase state PH1and the second phase state PH2show relative phase relationships between the hosel hole2010and the sleeve2000. A mutual shifting between the first phase state PH1and the second phase state PH2can be performed by rotating the sleeve2000with respect to the hosel hole2010.

In the first phase state PH1, the reverse-tapered engagement faces K1are opposed to the respective interference-avoiding faces J2.FIG. 26shows the first phase state PH1. As described above, in the first phase state PH1(FIG. 26), the hosel hole2010allows the tip engagement part RT (sleeve2000) to pass through the hosel hole2010. Although not clearly shown inFIG. 26, a (slight) clearance is present each between the reverse-tapered engagement faces K1and the respective interference-avoiding faces J2.

In the first phase state PH1, the non-engagement faces K2are opposed to the respective reverse-tapered hole faces J1. In the first phase state PH1, a gap is present each between the non-engagement faces K2and the reverse-tapered hole faces J1.

In the second phase state PH2, the reverse-tapered engagement faces K1are opposed to the respective reverse-tapered hole faces J1.FIG. 24(a)andFIG. 24(b)show the second phase state PH2. In the second phase state PH2, the engagement state is achieved. As described above, in the engagement state, the reverse-tapered engagement faces K1are brought into surface-contact with the respective reverse-tapered hole faces J1. In the second phase state PH2, the reverse-tapered engagement faces K1can be fitted to the respective reverse-tapered hole faces J1.

Thus, in assembling the golf club according to the present embodiment, the sleeve2000is fixed (bonded) to the tip end portion of a shaft. Next, the sleeve2000is inserted to the hosel hole2010from above, and is made to completely pass through the hosel hole2010. By the passing, the sleeve2000reaches the lower side of the sole, and the shaft is inserted to the hosel hole2010. In the passing process, the first phase state PH1is adopted (seeFIG. 26). Next, the sleeve2000fixed to the shaft is rotated so that the first phase state PH1is shifted to the second phase state PH2. The sleeve2000is exposed to the outside, and thus can be freely rotated. In the present embodiment, the angle of the rotation is 45 degrees. Finally, the shaft to which the sleeve2000is fixed is pulled up, and the reverse-tapered engagement faces K1are fitted to the respective reverse-tapered hole faces J1. This final state is shown inFIG. 24(a),FIG. 24(b)andFIG. 25.

Thus, the first phase state PH1enables the sleeve2000to pass through the hosel hole2010. The second phase state PH2enables the sleeve2000to be fitted to the hosel hole2010.

In the sleeve2000, a center line of the sleeve inner surface2002is not inclined with respect to a center line of the sleeve outer surface. Of course, the center line of the sleeve inner surface2002may be inclined with respect to the center line of the sleeve outer surface. The center line of the sleeve inner surface2002may be parallel and eccentric with respect to the center line of the sleeve outer surface.

In the present embodiment, a spacer is not used. However, a spacer can be provided. For example, the shape of the sleeve2000can be formed by a spacer and a sleeve. In this case, the outer shape of the sleeve may be a regular eight-sided pyramid having a reverse-tapered shape. The spacer suited to the sleeve may have an inner shape of a regular eight-sided pyramid corresponding to the outer shape of the sleeve, and may have an outer shape which is the same as the shape of the sleeve2000. When a spacer is used, an inclination angle can be set between the center line of the inner shape of the sleeve and the center line of the outer shape of the sleeve, and an inclination angle can be set between the center line of the inner shape of the spacer and the center line of the outer shape of the spacer. In this case, as described above, an independent variability of the loft angle and an independent variability of the lie angle can be attained.

A taper ratio of the reverse-tapered fitting is not limited. When the taper ratio is excessively small, it may be difficult to release the reverse-tapered fitting. Meanwhile, when the taper ratio is excessively large, the size of the fitting portion becomes large. An excessively large fitting portion deteriorates the degree of freedom of design of the golf club. In this respect, the taper ratio is preferably set within a predetermined range.

In the above-explained respects, the outer surface of the sleeve has a taper ratio of preferably equal to or greater than 0.2/30, more preferably equal to or greater than 0.5/30, and still more preferably equal to or greater than 1.0/30. In the above-explained respects, the taper ratio of the outer surface of the sleeve is preferably equal to or less than 5/30, more preferably equal to or less than 4/30, and still more preferably equal to or less than 3.5/30.

In the above-explained respects, the inner surface of the spacer has a taper ratio of preferably equal to or greater than 0.2/30, more preferably equal to or greater than 0.5/30, and still more preferably equal to or greater than 1.0/30. In the above-explained respects, the taper ratio of the inner surface of the spacer is preferably equal to or less than 5/30, more preferably equal to or less than 4/30, and still more preferably equal to or less than 3.5/30.

In the above-explained respects, the outer surface of the spacer has a taper ratio of preferably equal to or greater than 0.2/30, more preferably equal to or greater than 0.5/30, and still more preferably equal to or greater than 1.0/30. In the above-explained respects, the taper ratio of the outer surface of the spacer is preferably equal to or less than 10/30, more preferably equal to or less than 7/30, and still more preferably equal to or less than 5/30.

In the above-explained respects, the reverse-tapered hole has a taper ratio of preferably equal to or greater than 0.2/30, more preferably equal to or greater than 0.5/30, and still more preferably equal to or greater than 1.0/30. In the above-explained respects, the taper ratio of the reverse-tapered hole is preferably equal to or less than 10/30, more preferably equal to or less than 7/30, and still more preferably equal to or less than 5/30.

In the above-explained respects, the reverse-tapered engagement faces have a taper ratio of preferably equal to or greater than 0.2/30, more preferably equal to or greater than 0.5/30, and still more preferably equal to or greater than 1.0/30. In the above-explained respects, the taper ratio of the reverse-tapered engagement faces is preferably equal to or less than 10/30, more preferably equal to or less than 7/30, and still more preferably equal to or less than 5/30.

In the above-explained respects, the reverse-tapered hole faces have a taper ratio of preferably equal to or greater than 0.2/30, more preferably equal to or greater than 0.5/30, and still more preferably equal to or greater than 1.0/30. In the above-explained respects, the taper ratio of the reverse-tapered hole faces is preferably equal to or less than 10/30, more preferably equal to or less than 7/30, and still more preferably equal to or less than 5/30.

The definition of the taper ratio is as follows. When a length in an axial direction of the tapered surface is represented by Da, and a varied width in a direction perpendicular to the axial direction is represented by Db, then the taper ratio is Db/Da. In the taper ratio, varied amount in both sides, not an inclination (gradient) in one side, is considered. For example, in a case of a circular cone, the varied width Db is a varied amount of a diameter thereof, not a radius thereof. For example, in a case of a regular quadrangular pyramid, although the sectional shape of the regular quadrangular pyramid is a square, the varied width Db is a varied amount of the length of one side of the square.

The sectional area of the reverse-tapered hole is gradually increased toward the lower side (sole side). The sectional shape of the reverse-tapered hole is a non-circle. The sectional shape of the non-circle prevents relative rotation between the hosel hole and the tip engagement part. The non-circle includes all shapes other than a circle. For example, the non-circle may be a shape having a projection, a recess, or a flat portion at at least a part in the circumferential direction of a circle. The sectional shape of the reverse-tapered hole may be a polygon. Examples of the polygon include a triangle, a tetragon, a pentagon, a hexagon, a heptagon, an octagon, and a dodecagon. The polygon may be an N-sided polygon in which N is an even number, and examples of the N-sided polygon include the tetragon, the hexagon, the octagon, and the dodecagon. In light of anti-rotation, the tetragon, the hexagon and the octagon are preferable. The sectional shape of the reverse-tapered hole may be a regular polygon. Preferable examples of the regular polygon include a regular triangle, a regular tetragon (square), a regular pentagon, a regular hexagon, a regular heptagon, a regular octagon, and a regular dodecagon. The regular polygon is more preferably a regular N-sided polygon in which N is an even number, and examples of the regular N-sided polygon include the regular tetragon (square), the regular hexagon, the regular octagon, and the regular dodecagon. In light of anti-rotation, the regular tetragon, the regular hexagon, and the regular octagon are more preferable.

The reverse-tapered hole preferably includes a plurality of faces. Each of the faces may be a plane face, or may be a curved face. From the viewpoint of ensuring surface-contact with the tip engagement part, each of these faces is preferably a plane face. From the viewpoint of ensuring surface-contact with the tip engagement part, the reverse-tapered hole may be a pyramid surface. The pyramid surface means a part of the outer surface of a pyramid. Examples of the pyramid surface include a three-sided pyramid surface, a four-sided pyramid surface, a five-sided pyramid surface, a six-sided pyramid surface, a seven-sided pyramid surface, an eight-sided pyramid surface, and a twelve-sided pyramid surface. The pyramid surface is more preferably an N-sided pyramid surface in which N is an even number, and examples of the N-sided pyramid surface include the four-sided pyramid surface, the six-sided pyramid surface, the eight-sided pyramid surface, and the twelve-sided pyramid surface. In light of anti-rotation, the four-sided pyramid surface, the six-sided pyramid surface and the eight-sided pyramid surface are more preferable.

When the reverse-tapered hole faces J1are adopted as in the embodiment ofFIG. 21toFIG. 26, each of the reverse-tapered hole faces J1may be a plane face, or may be a curved face. From the viewpoint of ensuring surface-contact with the reverse-tapered engagement faces K1, each of the reverse-tapered hole faces J1is preferably a plane face. From the viewpoint of ensuring surface-contact with the reverse-tapered engagement faces K1, the reverse-tapered hole faces J1may constitute a pyramid surface. The pyramid surface means a part of the outer surface of a pyramid. Examples of the pyramid surface include a three-sided pyramid surface, a four-sided pyramid surface, a five-sided pyramid surface, a six-sided pyramid surface, a seven-sided pyramid surface, an eight-sided pyramid surface, and a twelve-sided pyramid surface. The pyramid surface is more preferably an N-sided pyramid surface in which N is an even number, and examples of the N-sided pyramid surface include the four-sided pyramid surface, the six-sided pyramid surface, the eight-sided pyramid surface, and the twelve-sided pyramid surface. In light of anti-rotation, the four-sided pyramid surface, the six-sided pyramid surface, and the eight-sided pyramid surface are more preferable.

The area of a figure formed by a sectional line of the outer surface of the sleeve is gradually increased toward the lower side (sole side). The sectional shape of the outer surface of the sleeve is a non-circle. The sectional shape of the non-circle prevents relative rotation between the sleeve and an abutting portion. The abutting portion is the inner surface of the spacer or the reverse-tapered hole. When a plurality of spacers are present, the abutting portion is the inner surface of the innermost spacer. The non-circle includes all shapes other than a circle. For example, the non-circle may be a shape having a projection, a recess, or a flat portion at at least a part in the circumferential direction of a circle. The sectional shape of the outer surface of the sleeve may be a polygon. Examples of the polygon include a triangle, a tetragon, a pentagon, a hexagon, a heptagon, an octagon, and a dodecagon. The polygon is preferably an N-sided polygon in which N is an even number, and examples of the N-sided polygon include the tetragon, the hexagon, the octagon, and the dodecagon. In light of anti-rotation, the tetragon, the hexagon, and the octagon are preferable. The sectional shape of the outer surface of the sleeve may be a regular polygon. Preferable examples of the regular polygon include a regular triangle, a regular tetragon (square), a regular pentagon, a regular hexagon, a regular heptagon, a regular octagon, and a regular dodecagon. The regular polygon is more preferably a regular N-sided polygon in which N is an even number, and examples of the regular N-sided polygon include the regular tetragon (square), the regular hexagon, the regular octagon, and the regular dodecagon. In light of anti-rotation, the regular tetragon, the regular hexagon, and the regular octagon are more preferable.

The outer surface of the sleeve preferably includes a plurality of faces. Each of the faces may be a plane face, or may be a curved face. From the viewpoint of ensuring surface-contact with the abutting portion, each of these faces is preferably a plane face. From the viewpoint of ensuring surface-contact with the abutting portion, the outer surface of the sleeve is preferably a pyramid surface. Examples of the pyramid surface include a three-sided pyramid surface, a four-sided pyramid surface, a five-sided pyramid surface, a six-sided pyramid surface, a seven-sided pyramid surface, an eight-sided pyramid surface, and a twelve-sided pyramid surface. The pyramid surface is more preferably an N-sided pyramid surface in which N is an even number, and examples of the N-sided pyramid surface include the four-sided pyramid surface, the six-sided pyramid surface, the eight-sided pyramid surface, and the twelve-sided pyramid surface. In light of anti-rotation, the four-sided pyramid surface, the six-sided pyramid surface and the eight-sided pyramid surface are more preferable.

As described above, the golf club may have one or more spacers. The inner surface of the spacer has the same shape as the shape of an outer surface of a member (inner member) fitted inside the spacer. The inner member is the sleeve or another spacer.

The area of a figure formed by a sectional line of the inner surface of the spacer is gradually increased toward the lower side (sole side). The sectional shape of the inner surface of the spacer is a non-circle. The sectional shape of the non-circle prevents relative rotation between the spacer and the inner member. When a plurality of spacers are present, the inner member is another spacer. The non-circle includes all shapes other than a circle. For example, the non-circle may be a shape having a projection, a recess, or a flat portion at at least a part in the circumferential direction of a circle. The sectional shape of the inner surface of the spacer may be a polygon. Examples of the polygon include a triangle, a tetragon, a pentagon, a hexagon, a heptagon, an octagon, and a dodecagon. The polygon is preferably an N-sided polygon in which N is an even number, and examples of the N-sided polygon include the tetragon, the hexagon, the octagon, and the dodecagon. In light of anti-rotation, the tetragon, the hexagon, and the octagon are preferable. The sectional shape of the inner surface of the spacer may be a regular polygon. Preferable examples of the regular polygon include a regular triangle, a regular tetragon (square), a regular pentagon, a regular hexagon, a regular heptagon, a regular octagon, and a regular dodecagon. The regular polygon is more preferably a regular N-sided polygon in which N is an even number, and examples of the regular N-sided polygon include the regular tetragon (square), the regular hexagon, the regular octagon, and the regular dodecagon. In light of anti-rotation, the regular tetragon, the regular hexagon, and the regular octagon are more preferable.

The inner surface of the spacer preferably includes a plurality of faces. Each of the faces may be a plane face, or may be a curved face. From the viewpoint of ensuring surface-contact with the inner member, each of these faces is preferably a plane face. From the viewpoint of ensuring surface-contact with the inner member, the inner surface of the spacer may be a pyramid surface. Examples of the pyramid surface include a three-sided pyramid surface, a four-sided pyramid surface, a five-sided pyramid surface, a six-sided pyramid surface, a seven-sided pyramid surface, an eight-sided pyramid surface, and a twelve-sided pyramid surface. The pyramid surface is more preferably an N-sided pyramid surface in which N is an even number, and examples of the N-sided pyramid surface include the four-sided pyramid surface, the six-sided pyramid surface, the eight-sided pyramid surface, and the twelve-sided pyramid surface. In light of anti-rotation, the four-sided pyramid surface, the six-sided pyramid surface and the eight-sided pyramid surface are more preferable.

As described above, the club of the present disclosure includes a tip engagement part. The tip engagement part may be constituted with only the sleeve, or may by constituted with the sleeve and one or more spacers. When the spacer is not used, the outer surface of the tip engagement part is the outer surface of the sleeve. When one spacer is used, the outer surface of the tip engagement part is the outer surface of the spacer. When two or more spacers are used, the outer surface of the tip engagement part is the outer surface of the outermost spacer.

The area of a figure formed by a sectional line of the outer surface of the tip engagement part is gradually increased toward the lower side (sole side). The sectional shape of the outer surface of the tip engagement part is a non-circle. The sectional shape of the non-circle prevents relative rotation between the tip engagement part and the reverse-tapered hole. The non-circle includes all shapes other than a circle. For example, the non-circle may be a shape having a projection, a recess, or a flat portion at at least a part in the circumferential direction of a circle. The sectional shape of the outer surface of the tip engagement part may be a polygon. Examples of the polygon include a triangle, a tetragon, a pentagon, a hexagon, a heptagon, an octagon, and a dodecagon. The polygon is preferably an N-sided polygon in which N is an even number, and examples of the N-sided polygon include the tetragon, the hexagon, the octagon, and the dodecagon. In light of anti-rotation, the tetragon, the hexagon, and the octagon are preferable. The sectional shape of the outer surface of the tip engagement part may be a regular polygon. Preferable examples of the regular polygon include a regular triangle, a regular tetragon (square), a regular pentagon, a regular hexagon, a regular heptagon, a regular octagon, and a regular dodecagon. The regular polygon is more preferably a regular N-sided polygon in which N is an even number, and examples of the regular N-sided polygon include the regular tetragon (square), the regular hexagon, the regular octagon, and the regular dodecagon. In light of anti-rotation, the regular tetragon, the regular hexagon, and the regular octagon are more preferable.

The outer surface of the tip engagement part preferably includes a plurality of faces. Each of the faces may be a plane face, or may be a curved face. From the viewpoint of ensuring surface-contact with the reverse-tapered hole, each of these faces is preferably a plane face. From the viewpoint of ensuring surface-contact with the reverse-tapered hole, the outer surface of the tip engagement part may be a pyramid surface. Examples of the pyramid surface include a three-sided pyramid surface, a four-sided pyramid surface, a five-sided pyramid surface, a six-sided pyramid surface, a seven-sided pyramid surface, an eight-sided pyramid surface, and a twelve-sided pyramid surface. The pyramid surface is more preferably an N-sided pyramid surface in which N is an even number, and examples of the N-sided pyramid surface include the four-sided pyramid surface, the six-sided pyramid surface, the eight-sided pyramid surface, and the twelve-sided pyramid surface. In light of anti-rotation, the four-sided pyramid surface, the six-sided pyramid surface and the eight-sided pyramid surface are more preferable.

When the tip engagement part RT is the sleeve2000(FIG. 21), the outer surface of the reverse-tapered engagement faces K1preferably includes a plurality of faces. Each of the faces may be a plane face, or may be a curved face. From the viewpoint of ensuring surface-contact with the reverse-tapered hole faces J1, each of these faces is preferably a plane face. From the viewpoint of ensuring surface-contact with the reverse-tapered hole faces J1, the outer surface of the reverse-tapered engagement faces K1preferably constitutes a pyramid surface. Examples of the pyramid surface include a three-sided pyramid surface, a four-sided pyramid surface, a five-sided pyramid surface, a six-sided pyramid surface, a seven-sided pyramid surface, an eight-sided pyramid surface, and a twelve-sided pyramid surface. The pyramid surface is more preferably an N-sided pyramid surface in which N is an even number, and examples of the N-sided pyramid surface include the four-sided pyramid surface, the six-sided pyramid surface, the eight-sided pyramid surface, and the twelve-sided pyramid surface. In light of anti-rotation, the four-sided pyramid surface, the six-sided pyramid surface and the eight-sided pyramid surface are more preferable.

Each of the above-mentioned numbers N is preferably an integer of equal to or greater than 3.

Thus, the reverse-tapered fitting is formed by the sleeve and the reverse-tapered hole while the spacer is interposed as necessary.

FIG. 27shows a golf club3100which is another embodiment.FIG. 27shows only the vicinity of a head of the golf club3100.FIG. 28is an exploded perspective view of the golf club3100.

The golf club3100has a head3200, a shaft3300, a sleeve3400, a spacer3500, and a grip (not shown in the drawings). The sleeve3400and the spacer3500constitute a tip engagement part RT.

The head3200has a hosel part3202. The hosel part3202has a hosel hole3204. The hosel hole3204has a reverse-tapered hole3206. The shape of the reverse-tapered hole3206corresponds to the shape of the outer surface of the tip engagement part RT. In other words, the shape of the reverse-tapered hole3206corresponds to the shape of the outer surface of the spacer3500.

The hosel part3202has a hosel slit3206. The hosel slit3206is provided lateral to the hosel part3202. The hosel slit3206is an opening formed between the inside of the hosel hole3204and the outside of the head. The hosel slit3206is opened to the axial-direction upper side, and is also opened to the axial-direction lower side. The hosel slit3206is provided on a heel side of the hosel part3202. Because of the hosel slit3206, a part of the reverse-tapered hole3206is lacking.

The head3200has a female screw part3220. The female screw part3220is provided on the lower side of the hosel part3202. The female screw part3220is provided on the lower side of the hosel hole3204.

Because of the presence of the slit3206, a part in the circumferential direction of the female screw part3220is lacking. However, the lack does not affect the screw-connection to the screw member600. The female screw part3220can be screw-connected to the male screw part604of the screw member600. The screw member600can be connected to the sleeve3400(sleeve-side connection part3410).

FIG. 28shows a width Ws of the hosel slit3206. The width Ws is larger than the diameter of the shaft3300. The width Ws is larger than at least the diameter of the thinnest portion of the shaft3300. Therefore, the hosel slit3206allows the shaft3300to pass therethrough. The hosel slit3206allows the shaft3300moving in the axial perpendicular direction to pass therethrough.

Because of the hosel slit3206, a part in the circumferential direction of the hosel hole3204is lacking. From the viewpoint of enhancing the retention for the tip engagement part RT, the width Ws is preferably small. For example, the width Ws may be larger than the diameter of the thinnest portion of an exposed part of the shaft3300. The exposed part means a part to which a sleeve and a grip are not attached, and is exposed to the outside. Needless to say, the width Ws is set so as not to allow passage of the tip engagement part RT. The tip engagement part RT cannot pass through the hosel slit3206.

The sleeve3400is the same as the above-described sleeve400. The sleeve3400has a sleeve-side connection part3410. The sleeve-side connection part3410is the same as the above-described sleeve-side connection part410. The sleeve3400is fixed to a tip end portion of the shaft3300. An adhesive is used for the fixation.

The shape of the spacer3500is the same as that of the above-described spacer500. However, the spacer3500does not have a divided structure. The spacer3500is an integral body as a whole.

FIG. 29shows a procedure of mounting the shaft3300of the golf club3100to the head3200.

In the mounting procedure, a shaft assembly3700is prepared first (step (a) inFIG. 29). The shaft assembly3700has a shaft3300, a sleeve3400, and a spacer3500. After the shaft3300has been inserted to the spacer3500, the sleeve3400is fixed to the tip end portion of the shaft3300, whereby the shaft assembly3700is obtained. In the shaft assembly3700, the sleeve3400is fixed to the shaft3300, but the spacer3500is not fixed to the shaft3300. In a state in which the shaft3300is inserted, the spacer3500can be moved in the axial direction (see step (a) inFIG. 29). However, because of the presence of the sleeve3400, the spacer3500will not fall off from the shaft3300.

Next, in the shaft assembly3700, the spacer3500is moved until it abuts on the outer surface of the sleeve3400(step (b) inFIG. 29). That is, the spacer3500is moved to the most distal side of the shaft assembly3700. This movement causes the spacer3500to be engaged with the sleeve3400, whereby the tip engagement part RT is formed.

Next, the shaft3300is made to pass through the hosel slit3206, whereby the shaft3300is moved to the inside of the reverse-tapered hole3206(step (c) inFIG. 29). As a result of the movement of the shaft3300, the tip engagement part RT is moved to the sole side of the head3200.

Next, the shaft3300(shaft assembly3700) is moved to the grip side along the axial direction, whereby the tip engagement part RT is fitted to the reverse-tapered hole3206(step (d) ofFIG. 29).

Finally, the screw member600is screwed to the female screw part3220. The male screw part604of the screw member600is screw-connected to the female screw part3220. By the screw-connection, the screw member600presses the tip engagement part RT to the upper side, whereby the engagement state is ensured. In addition, the screw member600is automatically connected to the sleeve3400.

In the present embodiment, the hosel slit3206is provided, and the shaft3300can pass through the hosel slit3206. Therefore, the sleeve3400may not be allowed to pass through the hosel hole3204. The spacer3500may not have a divided structure.

FIG. 30is a sectional view of the screw member600.FIG. 31is a sectional view showing a state in which the screw member600is connected to the sleeve400. In these sectional views, a center line CL of the screw member600is indicated by a one-dot chain line, and the illustration of portions on the lower side of the center line CL is omitted. The actual sectional views are line-symmetric about the center line CL as an axis of symmetry.

As described above, the screw member600has the screw-side connection part602, the male screw part604, and the rotating engagement part606. A detailed structure of the screw member600will be explained below.

The screw member600has a screw body610. A male screw part604is formed on an outer circumferential surface of the screw body610. The rotating engagement part606is provided on a bottom surface612of the screw body610. The rotating engagement part606is a recess having a non-circular sectional shape. By inserting a wrench to the rotating engagement part606, the screw body610can be rotated about the center line CL. The wrench preferably has a torque limiter. With the torque limiter, the force with which the screw member600presses the tip engagement part RT can be adjusted. From the viewpoint of the Golf Rules, the wrench is preferably used exclusively for the screw member600.

The screw-side connection part602has a first member620, a second member622, and a third member624. The first member620, the second member622, and the third member624each have a cylindrical shape as a whole. The first member620is exposed to the outside. The second member622is positioned inside the first member620. The second member622is fixed to the screw body610. The second member622may be integral with the screw body610. The second member622rotates with the rotation of the screw body610. The third member624is positioned inside the second member622. The first member620can be slidably moved with respect to the second member622. The third member624can be slidably moved with respect to the second member622.

The screw-side connection part602has a first elastic body630and a second elastic body632. The first elastic body630is a coil spring. The first elastic body630is a compression spring. The second elastic body632is a coil spring. The second elastic body632is a compression spring.

The screw-side connection part602has a ball634. The ball634is a steel ball. In the present application, the ball634is also referred to as an engagement ball.

The second member622has a ball housing hole636. The ball housing hole636is a through hole. The engagement ball634is disposed in the ball housing hole636. The diameter of the ball housing hole636is substantially equal to the diameter of the ball634. The engagement ball634can pass through the ball housing hole636.

The diameter of the ball634is larger than the depth of the ball housing hole636. For this reason, the ball634housed in the ball housing hole636is in a state of being projected inside or outside the second member622. InFIG. 30, the ball634is projected outside the second member622.

Although not shown in the drawings, the ball housing holes636are provided at a plurality of positions in the circumferential direction. The ball housing holes636are uniformly arranged in the circumferential direction. In the present embodiment, four ball housing holes636are arranged at 90° intervals. One ball634is disposed in each of the ball housing holes636. Here, the circumferential direction means the circumferential direction of the screw member600.

The second member622has a stopper638. The stopper638is an annular member disposed in a circumferential groove provided on the outer circumferential surface of the second member622. A circlip is used as the annular member.

The first elastic body630is disposed between (a step surface of) the first member620and (a step surface of) the second member622. The first elastic body630biases the first member620to a sleeve side (the right side inFIG. 30) with respect to the second member622.

The second elastic body632is disposed between (a step surface of) the screw body610and (a bottom surface of) of the third member624. The second elastic body632biases the third member624to the sleeve side (the right side inFIG. 30) with respect to the screw body610.

In the following, the state of the screw member600shown inFIG. 30is also referred to as a non-connected state, and the state of the screw member600shown inFIG. 31is also referred to as a connected state. The sleeve side is also referred to as an upper side, and the sole side is also referred to as a lower side. The right side inFIG. 30andFIG. 31is the upper side, and the left side inFIG. 30andFIG. 31is the lower side.

In the non-connected state (FIG. 30), the third member624is pressed to the upper side by the second elastic body632, and is located at a position P1on a relatively front side. In the position P1, the third member624abuts on the step surface of the second member622.

The third member624located at the position P1has a portion positioned inside the ball housing hole636. The third member624located at the position P1prevents the ball634from being projected inside. Therefore, in the non-connected state, the ball634is projected outside the second member622.

In the non-connected state (FIG. 30), the first member620is pressed to the upper side by the first elastic body630, but its movement to the upper side is regulated by the ball634being projected outside. As a result, in the non-connected state, the first member620is located at a position Px on a relatively lower side.

The first member620has an inclined surface640. The inclined surface640is a conical concave surface. The inclined surface640is inclined so as to extend toward the radially outward direction as going to the upper side. The radial direction means the radial direction of the screw member600. In the non-connected state, the inclined surface640abuts on the ball634.

When the male screw part604of the screw body610is screwed into the female screw part220(seeFIG. 5) of the head by rotating the screw member600(screw body610) in the first direction, the screw body610is moved to the upper side, and the second member622is also positioned on the upper side by being pressed by the screw body610. As a result, the entire screw member600is moved to the upper side.

When the movement of the screw member600to the upper side progresses as the rotation of the crew member600in the first direction is continued, the sleeve-side connection part410of the sleeve400is inserted inside the screw member600. More specifically, the sleeve-side connection part410is inserted inside the second member622. In the insertion, (a lower end surface of) the sleeve-side connection part410presses the third member624to the lower side against the biasing force of the second elastic body632. By the insertion of the sleeve-side connection part410, the third member624is moved to a position P2on a relatively lower side.

By this movement, the abutment between the third member624and the ball634is released. In place of the third member624, the engagement recess412of the sleeve-side connection part410reaches the same axial direction position as that of the ball634.

As described above, the ball634receives a pressing force from the inclined surface640by the biasing force of the first elastic body630, and the pressing force includes a component force to the inner side in the radial direction. Accordingly, the ball634falls in the engagement recess412that has been moved to the inner side in the radial direction of the ball634(FIG. 31). A part of the ball634is located within the engagement recess412, and the other parts thereof are located within the ball housing hole636. Therefore, the ball634locks the sleeve-side connection part410to the screw-side connection part602.

When the ball634falls in the engagement recess412, the abutment between the ball634and the first member620is released. As a result, the first member620is moved to a second position Py on a relatively upper side by the biasing force of the first elastic body630. At the second position Py, the first member620abuts on the stopper638. The connected state is achieved by the movement of the first member620.

As shown inFIG. 31, the first member620located at the second position Py prevents the ball634from being projected outside. Therefore, the state in which the ball634falls in the engagement recess412is maintained. That is, the connected state is maintained. As long as the second position Py of the first member620is maintained, it is not possible to pull out the sleeve-side connection part410from the screw member600.

Thus, by simply rotating the screw member600in the first direction with respect to the female screw part220, the sleeve400and the screw member600are automatically connected to each other, whereby the connected state is achieved (FIG. 31). In the connected state, the third member624is located at the position P2, the first member620is located at the position Py, and the ball634is engaged with the engagement recess412.

In the connected state, the screw member600presses the sleeve400to the upper side. Specifically, an upper end surface642of the second member622presses the sleeve400. As a result, the screw member600presses the sleeve400in the engaging direction. Therefore, the tip engagement part RT including the sleeve400is reliably fitted to the hosel hole204, whereby backlash resulting from the dimensional error can be eliminated.

Elimination of backlash is accompanied by the elastic deformation of the tip engagement part RT or the hosel hole204. Once fitting accompanied by the elastic deformation has been achieved, it will be difficult to release the fitting. That is, the tip engagement part RT is fitted into the hosel hole204, and thus is difficult to be pulled out from the hosel hole204. The connection between the screw member600and the sleeve400can solve this problem. When the screw member600is rotated in the second direction while maintaining the connected state, the screw member600is moved to the lower side, and the sleeve400is pulled in the engagement releasing direction by the screw member600. As a result, the tip engagement part RT including the sleeve400is pulled out from the hosel hole204.

As described above, the connection is maintained unless the first member620located at the second position Py is moved. Therefore, the connection is maintained when the screw member600is simply rotated in the second direction. The pulling-out of the tip engagement part RT is achieved by simply rotating the screw member600in the second direction.

To release the connection, the first member620may be moved to the lower side. The connected state can be released by moving the first member620to the position Px so as to bring about a state in which the ball634can be projected outside. The movement of the first member620is achieved by an external force. For example, the connected state can be released by simply moving the first member620to the lower side by fingers. The first member620can be moved by applying an external force greater than the biasing force of the first elastic body630.

Thus, the connection can be easily released. The connection may be released upon confirmation of pulling out of the tip engagement part RT including the sleeve400from the hosel hole204.

As explained above, in the present embodiment, by the rotation in the first direction DR1, the screw member600presses the tip engagement part RT in the engaging direction, and the sleeve-side connection part410is inserted to the screw-side connection part602. The connection between the sleeve-side connection part410and the screw-side connection part602is automatically completed by the sleeve-side connection part being inserted to the screw-side connection part. Therefore, by simply screwing the screw member600, the backlash between the tip engagement part RT and the head is eliminated, and the above-described connection that is effective for pulling out the tip engagement part RT is completed simultaneously.

In the present embodiment, the screw member600includes the screw body610having the male screw part604; the first member620constituting an outer circumferential surface of the screw-side connection part602; the second member622positioned inside the first member620; and the third member624positioned inside the second member622. The screw member600further includes the first elastic body630that is disposed between the first member620and the second member622, and biases the first member620to the sleeve side (upper side) with respect to the second member622; the second elastic body632that biases the third member624to the sleeve side (upper side); and the engagement ball634disposed in the ball housing hole636. The sleeve-side connection part410has the engagement recess412. In a non-connected state, the ball634is projected outside the second member622by the third member624being positioned inside the ball634, and by the projected ball634, the first member620is located at a first position Px at which movement thereof to the sleeve side is regulated. In a connected state in which the connection has been achieved, the third member624is moved to a position at which the third member624is removed from inside of the engagement ball634by the sleeve-side connection part410, the engagement ball634falls in the engagement recess412, and the movement regulation on the first member620by the engagement ball634is released, whereby the first member620is moved to a second position Py at which the first member620prevents the engagement ball634from projecting to the outside. Therefore, the above-described automatic connection is reliably achieved, and the connection can be easily released.

A mechanism used for a fluid coupling or an instant coupling may be adopted as the connecting structure of the screw-side connection part and the sleeve-side connection part. This mechanism is disclosed in Japanese Unexamined Utility Model Application Publication No. 60-108888, for example. Such a mechanism achieves connection by simply inserting one member into the other member, and the connection can be easily released, and therefore can be applied to the golf club according to the present disclosure.

FIG. 32andFIG. 33are sectional views showing a screw member650according to another embodiment, and a sleeve450corresponding to the screw member650.FIG. 32shows a non-connected state, andFIG. 33shows a connected state.

InFIG. 32andFIG. 33, a center line CL of the screw member650is indicated by a one-dot chain line, and the illustration of portions on the lower side of the center line CL is omitted. The actual sectional views are line-symmetric about the center line CL as an axis of symmetry.

The screw member650has a cylindrical shape as a whole. The screw member650includes a screw-side connection part652and a male screw part654. The screw member650further includes a rotating engagement part656. The rotating engagement part656is a hole coaxial with the center line CL. The sectional shape of the hole is a non-circle. The rotating engagement part656penetrates the screw member650.

The screw member650includes a screw body part660and an elastic deformation part662. The elastic deformation part662has an engagement projection664. The screw body part660has a cylindrical shape. The male screw part654is formed on the outer circumferential surface of the screw body part660. The elastic deformation part662is positioned on the upper side of the screw body part660.

The elastic deformation part662exhibits a shape resembling a bent bar as a whole. The elastic deformation part662extends from an upper end surface666of the screw body part660toward the upper side. The upper end (right end inFIG. 32) of the elastic deformation part662is a free end, and the engagement projection664is formed at the free end.

Although not shown in the drawings, the elastic deformation parts662are provided at a plurality of locations in the circumferential direction of the screw body part660. In the present embodiment, the elastic deformation parts662are provided at four locations in the circumferential direction of the screw body part660. All the elastic deformation parts662are bent so as to become closer to the center line of the screw member650with decreasing distance to the free end.

As described above, the rotating engagement part656penetrates the screw member650. More specifically, the rotating engagement part656penetrates the screw body part660. That is, the through hole penetrating the screw body part660constitutes a part of the rotating engagement part656. Furthermore, an inner surface668of the elastic deformation part662also constitutes a part of the rotating engagement part656. The inner surface668is continuous with the through hole penetrating the screw body part660.

The sleeve450has a shaft hole452. A shaft is inserted and bonded to the shaft hole452. InFIG. 32andFIG. 33, the illustration of the shaft is omitted.

The sleeve450has a sleeve-side connection part460. The sleeve-side connection part460has a cylindrical shape. The sleeve-side connection part460has a hollow portion461and an inner surface462. The hollow portion461is opened to the screw member650side. The inner side of the inner surface462constitutes the hollow portion461. The inner surface462defines the hollow portion461. The inner surface462is a circumferential surface. The inner surface462has an engagement recess464. The engagement recess464is a circumferential groove.

FIG. 32andFIG. 33show a wrench680used for rotating the screw member650. The sectional shape of the wrench680corresponds to the sectional shape of the rotating engagement part656. The sectional shape of the wrench680is a tetragon (square). As shown inFIG. 32andFIG. 33, the screw-connection between the male screw part654and the female screw part220is enabled by inserting the wrench680into the rotating engagement part656and rotating the wrench680.

As shown inFIG. 32, in a state in which an external force is not applied, the elastic deformation part662is bent. The state in which an external force is not applied is also referred to as a natural state. InFIG. 32, the wrench680is shallowly inserted. The wrench680remains at the screw body part660, and has not reached the inside of the elastic deformation part662. Therefore, the wrench680does not abut on the elastic deformation part662, and thus does not elastically deform the elastic deformation part662. An insertion position at which the elastic deformation part662is not elastically deformed is also referred to as a first insertion position Ps.

On the other hand, as shown inFIG. 33, the elastic deformation part662abuts on the wrench680when the wrench680is deeply inserted. As a result, the elastic deformation part662is elastically deformed so as to extend along the wrench680. The elastic deformation part662is straightened by the elastic deformation. The elastic deformation causes the engagement projection664of the elastic deformation part662to reach a position at which the engagement projection664is engaged with the engagement recess464of the sleeve-side connection part460. An insertion position at which the engagement projection664is engaged with the engagement recess464is also referred to as a second insertion position Pd.

Although a gap is present between the elastic deformation part662and the wrench680inFIG. 33, the gap is not actually present. The elastic deformation part662is deformed to the outer side by abutting on the wrench680, and is thereby straightened.

Such a screw member650can also fulfill the same function as that of the above-described screw member600. To press the sleeve450in the engaging direction, the screw member650is screwed into the female screw part of the head. At this time, the wrench680is inserted shallowly. That is, the wrench680is positioned at the first insertion position Ps. While maintaining the shallow insertion (first insertion position Ps), the screw member650is rotated in the first direction DR1. Then, the screw-connection of the screw member650progresses while the natural state of the elastic deformation part662is maintained. In the elastic deformation part662in the natural state, the engagement projection664is positioned on the inner side of the inner surface462. Therefore, the elastic deformation part662is smoothly inserted inside the sleeve-side connection part460. Finally, a lower end surface470of the sleeve-side connection part460abuts on an abutting surface666of the screw member650, whereby the sleeve450is pressed in the engaging direction.

To remove the screw member650, the wrench680is inserted deeply. That is, the wrench680is positioned at the second insertion position Pd (FIG. 33). This insertion causes the elastic deformation part662to be elastically deformed, whereby the engagement projection664is engaged with (caught by) the engagement recess464. That is, the screw member650is connected to the sleeve450. While maintaining the deep insertion (second insertion position Pd), the screw member650is rotated in the second direction DR2. Then, the screw member650is moved to the lower side while the connection between the screw member650and the sleeve450is maintained. As a result, the tip engagement part RT including the sleeve450is pulled out from the hosel hole204. The connection between the screw member650and the sleeve450can be easily released by inserting the wrench680shallowly.

Thus, the connection can be easily released. The connection may be released upon confirmation of pulling out of the tip engagement part RT including the sleeve450from the hosel hole204.

As explained above, the screw member650includes: the screw body part660having the male screw part654; the elastic deformation part662extending from the screw body part660to the sleeve side (upper side) and constituting the screw-side connection part652; and the rotating engagement part656to which a wrench680for rotating the screw member650can be inserted. The rotating engagement part656has a through hole658penetrating the screw body part660, and an inner surface668of the elastic deformation part662that extends continuously with the through hole658. The elastic deformation part662has the engagement projection664at an end portion thereof on the sleeve side, and the end portion on the sleeve side is a free end. The sleeve-side connection part460has the hollow portion461opened on the screw member650side, the inner surface462defining the hollow portion461, and the engagement recess464provided on the inner surface462. In a natural state, the elastic deformation part662including the engagement projection664exhibits a shape that can be inserted to the hollow portion461with rotation of the screw member650in the first direction DR1. When the wrench680is inserted to a position at which the wrench680abuts on the inner surface668of the elastic deformation part662, the elastic deformation part662is elastically deformed so as to be positioned at a position at which the engagement projection664of the elastic deformation part662can be engaged with the engagement recess464.

With this configuration, the wrench680can be inserted shallowly when rotating the screw member650in the first direction DR1, whereby the pressing of the tip engagement part RT is enabled. The wrench680can be inserted deeply when rotating the screw member650in the second direction DR2, whereby the pulling out of the tip engagement part RT is enabled.

A modification example of the embodiment shown inFIG. 32andFIG. 33is also possible. In the present modification example, the configuration of the embodiment shown inFIG. 30andFIG. 31is applied to the embodiment shown inFIG. 32andFIG. 33. In the present modification example, engagement using the engagement ball634is used in place of the engagement using the elastic deformation part662and the engagement projection664. In the present modification example, the engagement ball634is disposed at the screw-side connection part652. The engagement ball634is disposed at the position corresponding to the engagement projection664. When the wrench680is inserted deeply, the engagement ball634is pressed by the wrench680from inside so as to be projected outside, and is thereby engaged with the engagement recess464. By this engagement, the screw member650is connected to the sleeve450. Therefore, when the screw member is rotated in the second direction DR2while maintaining the deep insertion of the wrench680, the sleeve450is pulled in the engagement releasing direction. When the wrench680is inserted shallowly, the abutment between the wrench680and the engagement ball634is released so as to bring about a state in which the engagement ball634can be retracted inside. By bringing about this state, the connection between the sleeve450and the screw member650can be released. The screw-side connection part652is configured such that the engagement ball634does not fall off from the screw-side connection part652even in a state in which the wrench680is not present. For example, the engagement ball634may be disposed in a ball housing hole636provided on the screw-side connection part652, and (small) stoppers to prevent the falling-off of the engagement ball634may be provided on both sides of the ball housing hole636.

As shown inFIG. 12toFIG. 17and so forth, the position of the sleeve on the sole side is changed by the above-described angle adjustment. That is, when a spacer that makes the sleeve inclined is used, the position of the lower end of the sleeve is changed. For this reason, the position of the sleeve-side connection part may also be changed. The connecting mechanism of the sleeve-side connection part and the screw member preferably has a mechanism capable of absorbing the position change of the lower end of the sleeve. The sleeve preferably has a displacement mechanism in which the sleeve-side connection part can be displaced with respect to the sleeve body so as to correspond to the position change of the lower end of the sleeve. The displacement mechanism is preferably configured to enable the connection between the sleeve-side connection part and the screw member over the entire movement range of the lower end of the sleeve.

FIG. 34andFIG. 35are sectional views of an embodiment including a sleeve sv1having the above-described displacement mechanism and a screw member600acorresponding to the sleeve sv1. In the present embodiment, one spacer sp1is used.

The sleeve sv1has a sleeve body sv2and a movable connection part sv3. The sleeve body sv2has a movable space r1. The sleeve body sv2further has an opening r2that allows communication between the movable space r1and the outside. The movable space r1and the opening r2are provided at a bottom surface portion of the sleeve body sv2.

The movable connection part sv3has a body sv31, a falling-off prevention part sv32, and a joining part sv33.

The body sv31constitutes a sleeve-side connection part. The body sv31has a tip tapered surface tp1. Except for the presence of the tip tapered surface tp1, the outer shape of the body sv31is the same as that of the above-described sleeve-side connection part410.

The falling-off prevention part sv32is disposed in the movable space r1. The falling-off prevention part sv32can move inside the movable space r1.

The joining part sv33joins the body sv31to the falling-off prevention part sv32.

The joining part sv33penetrates the opening r2. The sectional area of the opening r2is larger than the sectional area of the joining part sv33. The joining part sv33can be moved inside the opening r2. The movable space r1has a dimension that can ensure the necessary movement and inclination of the falling-off prevention part sv32. The falling-off prevention part sv32has a size that cannot pass through the opening r2.

The movable connection part sv3is held by the sleeve body sv2in a state in which it hangs from the sleeve body sv2. The movable connection part sv3can be moved relative to the sleeve body sv2within a range that can follow the position change of the sleeve on the sole side. The movable connection part sv3can be inclined relative to the sleeve body sv2within a range that can follow the position change of the sleeve on the sole side.

The screw member600ahas a receiving slope690. The receiving slope690is a conical concave surface. Except for the presence of the receiving slope690, the screw member600ais the same as the above-described screw member600. The receiving slope690is provided at an upper end surface of the second member622(seeFIG. 31). The receiving slope690is inclined outward as going to the upper side.

In state (a) inFIG. 34, the center line of the outer surface of the sleeve sv1is shifted to the right side with respect to the center line of the screw member600a. However, the movable connection part sv3can be moved so as to absorb the shift between the center lines. As a result of the movement, the screw member600acan be connected to the sleeve sv1. That is, state (b) inFIG. 34is realized. The abutment between the tip tapered surface tp1and the receiving slope690contributes to smooth movement of the movable connection part sv3.

In state (a) inFIG. 35, the center line of the outer surface of the sleeve sv1is shifted to the left side with respect to the center line of the screw member600a. In this case as well, the movable connection part sv3can be moved so as to absorb the shift between the center lines. As a result of the movement, the screw member600acan be connected to the sleeve sv1. That is, state (b) inFIG. 35is realized. The abutment between the tip tapered surface tp1and the receiving slope690contributes to smooth movement of the movable connection part sv3.

As explained above, the sleeve sv1has a sleeve body sv2and a movable connection part sv3, and the movable connection part sv3is configured to be movable with respect to the sleeve body sv2. When the screw member600ais rotated in the first direction, an upper end portion of the screw member and a lower end portion of the movable connection part abut on each other. By the abutment, the movable connection part is moved to a position at which it can be connected to the screw member600a. Therefore, the sleeve and the screw member can be connected to each other even when the position of the lower end of the sleeve is changed.

Each of the above-described screw members plays the role (role A) of pressing the tip engagement part RT in the engaging direction, and the role (role B) of pulling the tip engagement part RT in the engagement releasing direction. These screw members can also be used to play only the role B. For example, the role A can be replaced by another screw member that does not have the connecting function to the sleeve. A screw member having the above-described connecting function can be used only when the tip engagement part RT is removed from the reverse-tapered hole. In this case, the screw member mounted to the golf club being used can be a screw member that does not have the connecting function, so that the weight of the golf club can be reduced.

The material of the sleeve is not limited. Preferable examples of the material include a titanium alloy, stainless steel, an aluminum alloy, a magnesium alloy, and a resin. From the viewpoint of strength and lightweight properties, for example, the aluminum alloy and the titanium alloy are more preferable. It is preferable that the resin has excellent mechanical strength. For example, the resin is preferably a resin referred to as an engineering plastic or a super-engineering plastic.

The material of the spacer is not limited. Preferable examples of the material include a titanium alloy, stainless steel, an aluminum alloy, a magnesium alloy, and a resin. From the viewpoint of strength and lightweight properties, for example, the aluminum alloy and the titanium alloy are more preferable. It is preferable that the resin has excellent mechanical strength. For example, the resin is preferably a resin referred to as an engineering plastic or a super-engineering plastic. From the viewpoint of moldability, the resin is preferable.

As described above, the golf clubs may include an adjusting mechanism capable of adjusting the position and/or angle of the center line of the shaft. The adjusting mechanism includes a connecting mechanism between a screw member and a sleeve. This mechanism preferably satisfies the Golf Rules defined by The R&A (The Royal and Ancient Golf Club of St Andrews). That is, the mechanism preferably satisfies requirements specified in “lb. Adjustability” in “1. Clubs” of “Appendix II. Design of Clubs” defined by The R&A. The requirements specified in “lb. Adjustability” are the following items (i), (ii), and (iii):

(i) the adjustment cannot be readily made;

(ii) all adjustable parts are firmly fixed and there is no reasonable likelihood of them becoming loose during a round; and

(iii) all configurations of adjustment conform to the Rules.

The disclosure described above can be applied to all golf clubs such as a wood type golf club, a hybrid type golf club, an iron type golf club, and a putter.

The above description merely shows illustrative examples, and various modifications can be made.