Golf club, method for changing shaft insertion depth of golf club, and method for replacing shaft of golf club

A golf club, includes: a head; a shaft; a shaft case, having a cylindrical shape and fixed to a leading end of the shaft, a hosel, mounted on the head, wherein: the shaft case is inserted into the hosel from an upper end of the hosel; and the shaft case is fixed to the hosel so that an insertion depth of the shaft into the hosel is changed.

BACKGROUND

1. Field of the Invention

The present invention relates to a golf club. Specifically, the invention relates to a golf club the shaft of which can be replaced easily. Also, the invention relates to a method for changing the shaft insertion depth of such golf club and a method for replacing the shaft of such golf club.

2. Description of the Related Art

A golf club is structured such that a head is mounted on the leading end portion of a shaft, while a grip is mounted on the base end portion of the shaft.

Referring to the structure of a conventional ordinary golf club head, a hosel hole is formed directly in the head, while the shaft is inserted into the hosel hole and is fixed thereto using an adhesive agent. Here, as the adhesive agent, generally, there is used an epoxy-system adhesive agent. To replace the shaft, the hosel portion of the head may be heated to destroy the structure thereof that is formed of the hardened epoxy resin of the adhesive agent, whereby the shaft can be then pulled out of the hosel portion of the head.

In JP-A-11-178954, there is disclosed a golf club head structured such that a head main body and a hosel are produced separately from each other and the hosel is then fixed to the head main body using a screw. In JP-A-11-178954, a plate-shaped neck portion is formed on the lower end side of the hosel, and the neck portion is inserted into the insertion portion of the head main body and is fixed thereto using a screw. Thus, since the plate-shaped neck portion is fixed to the head main body in this manner, in the impact time when a golfer hits a ball with the head, the neck portion is allowed to bend, thereby relieving the concentration of stresses occurring in the connecting portion between the shaft and hosel.

In the golf club head disclosed in JP-A-11-178954, the shaft insertion depth of the head cannot be changed.

Thus, it is an object of the invention to provide a golf club the shaft case insertion depth of which can be changed and a method for changing the shaft insertion depth of such golf club.

Also, in the golf club head disclosed in JP-A-11-178954, the connecting strength between the head main body and hosel as well as the rigidity thereof are both insufficient, whereby a strong impact feeling cannot be obtained. Also, the position of the hosel is excessively high.

SUMMARY

According to an aspect of the invention, there are provided a golf club structured such that a shaft equipped with a shaft case, which is formed separately from a head, can be strongly fixed to the head and the shaft case can be easily mounted onto and removed from the head; and, a method for changing the shaft insertion depth of such golf club and a method for replacing the shaft of such golf club.

According to an aspect of the invention, there is provided a golf club, includes: a head; a shaft; a shaft case, having a cylindrical shape and fixed to a leading end of the shaft, a hosel, mounted on the head, wherein: the shaft case is inserted into the hosel from an upper end of the hosel; and the shaft case is fixed to the hosel so that an insertion depth of the shaft into the hosel is changed.

The shaft case may be fixed to the hosel by a ring-shaped screw member removably screwed on the upper end of the hosel.

A lower end of the shaft case may be closed, an upper end of the shaft case may be opened, and the shaft may be inserted into the shaft case and is fixed thereto using an adhesive agent.

The golf club may includes: a spacer, disposed between the lower end of the shaft case and a bottom portion of the hosel; a female screw, formed in an inner peripheral surface of the upper end of the hosel; a first screw member, threadedly engaged with the upper end of the hosel, the first screw member being concentrically with the hosel; a female screw, formed in the inner peripheral surface of an upper end of the first screw member; a second screw member, including a male screw being threadedly engaged with the female screw of the first screw member, wherein when the spacer and the first screw member are removed and the second screw member is threadedly engaged with the female screw of the hosel directly, the insertion depth of the shaft is increased.

A lower end face of the screw member may be pressed against an upper end face of the shaft case.

The golf club may include a projecting portion, provided on an outer peripheral surface of the shaft case.

The lower end face of the second screw member may be pressed against the projecting portion.

The spacer may include an engaging unit, configured to engage a jig which is used to pull out the spacer from the hosel.

The engaging unit may be a female screw.

A method for changing the shaft insertion depth of the golf club, the method includes: removing the second screw member from the first screw member; removing the first screw member from the hosel; pulling out the shaft case from the hosel; taking out the spacer from the hosel; inserting the shaft case into the hosel; and threadedly engaging the second screw member with the hosel.

A method for changing the insertion depth of the shaft of the golf club, the method includes: replacing the second screw member and spacer with another second screw member and spacer which are different in length in the axial direction of the hosel.

The method according to the above, may further includes: providing a weight adjusting portion in the head; and adjusting the insertion depth based on a weight of the head.

A method for replacing the shaft of the golf club, the method includes: fixing a new shaft to a new shaft case to form a connected unit; removing the shaft case and the shaft from the head; and mounting the connected unit onto the head.

According to a golf club of the invention, the insertion depth of the shaft into the hosel can be adjusted. Therefore, in a golf club including the same head and the same shaft, when the length of the shaft case is changed, a golfer can easily find the length of the shaft suitable for the golfer.

According to a golf club as set forth in Claim2, since the shaft case is inserted into the cylindrical hosel and is fixed thereto with a screw member, the shaft case can be mounted onto the hosel firmly.

According to a golf club as set forth in Claim3, the shaft can be inserted into the deep portion of the shaft case and can be thereby bonded thereto firmly.

According to a golf club as set forth in Claims2to7, by changing the insertion depth of the shaft case, the shaft insertion depth can be changed.

According to a shaft insertion depth changing method as set forth in Claim9, by removing the spacer and cylindrical member, the shaft insertion depth can be increased or changed. When the removed spacer and cylindrical member are mounted again, the shaft insertion depth can be reduced.

According to a shaft insertion depth changing method as set forth in Claim10, by replacing the spacer and cylindrical member with another spacer and cylindrical member which are different in length in the hosel axial direction from the existing ones, the shaft insertion depth can be changed.

According to a shaft replacing method as set forth in Claim12, when the screw member is loosened and removed, the shaft case can be pulled out of the hosel. Specifically, a new shaft case is connected to a shaft to provide a new shaft case/shaft connected unit previously. And, when the new shaft case/shaft connected unit is inserted into the above hosel and the screw member is threadedly engaged, the shaft can be replaced.

According to this shaft replacing method, it is possible to omit a conventional troublesome labor and time requiring operation in which the adhesive agent is heated to destroy the structure of the adhesive agent, an existing shaft is removed from the head main body, and a new shaft is then mounted again onto the head main body using an adhesive agent. Therefore, an existing shaft can be removed from the head of a golf club just after it is used for a ball hitting try, and another new shaft having different properties can be mounted quickly onto the same head for another hitting trial using the golf club. Owing to this, in a golf shop and the like, it is very easy for the golfer to find a proper golf club.

DETAILED DESCRIPTION OF THE INVENTION

Now, description will be given below of a first embodiment according to the invention with reference to the accompanying drawings.

Specifically,FIG. 1is a front view of a golf club head according to a first embodiment of the invention.FIG. 2is a side view of the heel side of the golf club head.FIG. 3is a section view taken along the arrow line shown inFIG. 1.FIG. 4is an exploded perspective view of the golf club head.FIG. 5is a perspective view of a hosel, a spacer, a shaft case and a screw member.FIG. 6is a section view of the hosel, spacer, shaft case and screw member.FIG. 7is a perspective section view of the hosel.FIG. 8is a section view of the golf club according to the present embodiment, showing a case when the spacer and screw member are removed and the shaft is inserted deeply.

Referring to the structure of this golf club, a shaft4is mounted on the hosel3of a head1through a shaft case5, screw members6,8and a spacer7.

This head1includes a head main body2and a hosel3mounted on the head main body2, while the head1is of a hollow wood type. And, the head main body2includes a face portion2a, a crown portion2b, a sole portion2c, a toe portion2d, a heel portion2eand a back portion2f.

As shown inFIG. 3, in such portion of the crown portion2bas faces the face portion2aand heel portion2e, there is formed a cylindrical hosel installation portion2g. This hosel installation portion2ghas a cylindrical shape with its upper end opened and its lower end closed, while this portion2gextends coaxially with the shaft4. The hosel3is inserted into the hosel installation portion2gfrom above and is fixed there using proper fixing means such as welding, brazing, bonding, shrinkage fitting and expansion fitting.

As shown inFIGS. 5 to 7, the hosel3has a substantially cylindrical shape including a hole which is formed to extend in the axial direction of the hosel3from its upper end toward its lower end.

On the entrance side of the hole, that is, in the inner peripheral surface of the hosel upper end side of the hole, there is formed a female screw3a. Continuously with the lower end portion of the female screw3a, there is formed a step portion3bwhich extends in the decreasing diameter direction of the hosel3; and the portion of the hosel3, which exists more deeply than the step portion3b, is formed as a cylindrical portion3c. More deeply of the cylindrical portion3c, there are formed a pair of inclined surfaces3dand3dwhich respectively cross the axis of the hosel3obliquely. The two inclined surfaces3dand3dare arranged symmetrically with the axis of the hosel3between them. The distance between the two inclined surfaces3dand3d, that is, the spacing between them in the perpendicularly crossing direction with the hosel axis decreases toward the lower end of the hosel3. The crossing angle θ (FIG. 6) between the two inclined surfaces3dand3dmay preferably be approximately 10 to 30°, more preferably, approximately 15 to 20°. Here, although not shown, the deep portion of the hosel hole may also be formed to have a pyramid shape such as a square pyramid shape.

As shown inFIGS. 5 and 6, the shaft case5is a cylindrical member which is very slightly smaller in diameter than the cylindrical portion3cof the hosel3. The shaft case5includes a hole5afor insertion of the shaft4extending from the upper end portion of the shaft case5toward the lower end portion thereof. The length of the cylindrical portion of the hole5amay be approximately 10 mm or more, for example, approximately 10 to 50 mm, more preferably, approximately 20 to 40 mm. In such portion of the shaft case5as exists from the deep bottom surface of the hole5ato the lower end face of the shaft case5, there is opened up a small hole5bfor air bleeding. Here, the cylindrical portion of the shaft case hole5amay preferably extend to a position where the inclined surfaces3dare formed. According to the present embodiment, since impacts generated in the hitting time are to be received by the inclined surfaces3d, the present golf club can provide a hitting feeling which is near to an ordinary golf club structured such that a head and a shaft are fixed to each other using an adhesive agent.

In the outer surface of the lower end side of the shaft case5, there are formed a pair of inclined surfaces5cand5c. The inclined surfaces5cand5care arranged symmetrically with the axis of the shaft case5between them. The distance between the two inclined surfaces5c,5c, that is, the spacing between them in the perpendicularly crossing direction with the axis of the shaft case5decreases toward the lower end side of the shaft case5. The crossing angle between the two inclined surfaces5cand5cis the same as the crossing angle θ between the two inclined surfaces3dand3d.

Here, although not shown, the inner peripheral edge of the upper end portion of the shaft case5may also be chamfered at an angle of approximately 20 to 45° for easy insertion of the shaft4. Also, the outside diameter of the upper end portion of the shaft case5may also be increased to thereby form such upper end portion as a flange-like portion. In this case, as will be discussed later, when the lower end face of the screw member8is pressed against the upper end face of the shaft case5, the pressing area can be increased.

Between the shaft case5and the deepest portion of the hosel3, there is interposed a spacer7. The spacer7has a V-like shape when it is viewed from the side surface thereof. And, the spacer7includes a bottom portion7band a pair of rising portions7a,7arespectively rising from the bottom portion7b. The spacer7includes a pair of outer inclined surfaces7dand7dwhich can respectively be engaged with the inclined surfaces3dand3dof the hosel3, and a pair of inner inclined surfaces7cand7crespectively engageable with the inclined surfaces5cand5cof the shaft case5. Thus, the spacer7includes an outer surface shape fittable with the deepest portion of the hosel3and an inner surface shape with which the shaft case5can be fitted.

In the bottom portion7bof the spacer7, there is formed a female screw hole7h. When the leading end of an elongated rod-like jig is screwed into this female screw hole7h, the spacer7can be easily inserted into and removed from the hosel3. In order to prevent the spacer7from shaking or generating strange sounds, preferably, the spacer7may be made of metal, more preferably, it may be made of an alloy, most preferably, it may be made of a titanium alloy, a magnesium alloy, or an aluminum alloy having a low specific gravity. Also, for prevention of the strange sounds, the spacer7may also be made of elastic material such as rubber or elastomer; and also, it may also be made of foaming material such as foaming rubber, foaming resin or foaming elastomer, because the foaming material has a low specific gravity. The thickness of the spacer7may be 0.25 inches (6.3 mm) or more, more preferably, approximately 0.25 to 1.5 inches. When preparing spacers having different thicknesses, preferably, they may be prepared at regular intervals, for example, 0.25″, 05″, 0.75″, 1.0″ - - - . In this case, for the first screw member6as well, preferably, there may be prepared screw members which respectively correspond to the respective lengths of spacers used.

The first screw member6has a substantially ring-like shape. The lower half portion of the first screw member6is formed smaller in diameter than the upper half portion6athereof and, in the outer peripheral surface of the lower half portion, there is formed a male screw6b. The lower half portion of the screw member6has such diameter as allows the male screw6bto be threadedly engaged with the female screw3aof the hosel3. The screw member6includes a hole6cwhich penetrates through the screw member6in the axial direction of the screw member6and into which the shaft case5can be inserted. The upper portion of the hole6cis formed larger in diameter than the lower portion of the hole6cand includes a female screw6d. Between the large-diameter upper portion of the hole6cand the small-diameter lower portion thereof, there is interposed a step surface6m(FIG. 6).

The vertical thickness t of the large diameter portion6aof the screw member6is set equal to the thickness t of the bottom portion7bof the spacer7.

The second screw member8includes a male screw8bformed in the outer periphery of the cylindrical lower half portion thereof, while the upper half portion of the second screw member8is formed as a tapered umbrella-shaped portion8athe diameter of which decreases as it goes toward its upper end. The diameter of the lower end of the umbrella-shaped portion8ais set equal to the diameter of the upper half portion6aof the screw member6.

The screw member8includes a hole8cwhich penetrates through the screw member8in the vertical direction. The diameter of the hole8cis set slightly larger than the diameter of the shaft4. On the inner peripheral surface of the hole8c, there is mounted an O ring8rmade of rubber, elastomer or the like and the inner periphery of the O ring8ris contacted with the shaft4. This can enhance the sliding performance between the shaft4and the inner peripheral surface of the hole8cand also can prevent the shaft4against shaking motion. Also, between the first and second screw members6and8, between the screw member6and hosel3, and between the screw member8and the end face of the shaft case5, there are respectively interposed ring-shaped thin layers9each made of elastic material such as rubber or elastomer.

To assemble the golf club, as shown inFIG. 4, the screw members8and6are respectively fitted with shaft4from the leading end side of the shaft4and the shaft case5is fixed to the leading end of the shaft4using an adhesive agent previously. Preferably, the adhesive agent may be applied to the outer peripheral surface of the leading end portion of the shaft4, and the shaft4may be then inserted into the deepest portion of the hole5aof the shaft case5.

Here, since the small hole5bis formed in the shaft case5, when the shaft4is inserted into the hole5aof the shaft case5, the air is allowed to flow out through the small hole5b. As the adhesive agent, preferably, there may be used an epoxy-system adhesive agent.

The screw member6is fitted with the outer surface of the shaft case5. The screw members6and8are fitted in this manner and also the shaft case5of a shaft case/shaft connected unit, in which the shaft case5is fixed to the shaft4, is inserted into the hosel3of the head1through the spacer7as shown inFIGS. 3 to 6. And, the shaft case5and spacer7are respectively inserted into the hosel3. As clearly shown inFIG. 6, the inclines surfaces5cand5care made to face the inclined surfaces7cand7crespectively, while the inclined surfaces7c,7cand inclines surfaces3d,3dare superimposed on top of each other. Next, the male screw6bof the screw member6is threadedly engaged into the female screw3aof the hosel3. Further, the male screw8bof the screw member8is threadedly engaged into the female screw6dof the screw member6.

Thus, as shown inFIG. 3, the lower end face of the screw member8is contacted with the upper end face of the shaft case5and the lower portion of the shaft case5including the inclined surfaces5cis engaged with the inclined surfaces3dof the hosel3through the spacer7, whereby the shaft case5is fixed to the hosel3. This completes the assembling of the golf club in which the shaft4and head1are connected together as an integral body, because the shaft case5and shaft4are firmly bonded to each other with the adhesive agent. In this golf club, since the shaft case5equipped with the shaft4is inserted into the hosel3and is then fixed there using the screw members6and8, the mounting strength and rigidity of the shaft4and shaft case5are high.

Here, when the spacer7is made of rubber, elastomer, synthetic resin or the like, the spacer can absorb impacts and vibrations caused in the impact time.

To increase the insertion depth of the shaft4, as shown inFIG. 8, the spacer7and screw member6are removed and the male screw8bof the screw member8is threadedly engaged directly into the male screw3aof the hosel3. In this case, the shaft4can be inserted into the hosel4more deeply by an amount equivalent to the thickness t of the spacer7. Here, in this case, preferably, there may be interposed a thin-piece-shaped elastic member10made of rubber, elastomer, synthetic resin or the like between the inclined surfaces3dof the hosel3and the inclined surfaces5cof the shaft case5to thereby be able to absorb the above-mentioned impacts and vibrations.

Alternatively, instead of removing the spacer7and screw member6, by replacing the spacer7and screw member6with another spacer and screw member having different dimensions in the axial direction of the hosel3, the insertion depth of the shaft4can be changed.

According to the present embodiment, due to formation of the female screw7hin the spacer7, when a rod-shaped jig having a male screw in the leading end thereof is screwed into the hosel3and the male screw is threadedly engaged with the female screw7h, the spacer7can be taken out from the hosel3easily. To mount the spacer7into the hosel3as well, this jig may also be used.

To replace the shaft of the golf club, a shaft case of the same type as the shaft case5may be previously fixed to a new shaft to be used as a replacement using an adhesive agent. Here, the screw member8may also be mounted on the shaft previously. As the need arises, the screw member6may also be mounted previously.

The screw member8of the existing golf club is removed, and the old shaft4is removed from the head1together with the old shaft case5and screw member8. Next, the new shaft with a shaft case and screw member connected thereto (the shaft case/shaft connected unit) is inserted into the head1and is then fixed thereto by tightening the screw member8.

Thus, according to the present embodiment, the mounting and replacement of the shaft can be carried out very simply and quickly. Here, conventionally, to replace a shaft, the hosel portion of an existing golf club is heated to destroy the structure of the hardened material of an adhesive agent, an existing shaft is removed and, after then, a new shaft is fixed to the hosel portion of the head using an adhesive agent. This shaft replacing operation requires about several hours to one day or so. On the other hand, according to the above embodiment of the invention, since a new shaft is previously mounted on the shaft case5using an adhesive agent, the shaft replacing operation can be carried out in several minutes or so. Therefore, it is possible to realize a golf club using system in which there are previously prepared multiple shafts having various specifications, each shaft having a shaft case connected thereto, and the prepared different shafts are mounted sequentially one by one onto the same head main body for successive hitting trials.

According to the present embodiment, the arrangement of the inclined surfaces3d,5c,7cand7dcan reduce the shaking motion of the shaft4and also can prevent the shaft4from rotating around the axial direction of the shaft4. That is, the fixation rigidity of the shaft4in the torque direction is high.

Also, since the paired inclined surfaces5cand5care arranged and the leading end portion of the shaft case5is thereby tapered, the shaft case5can be inserted into the hosel3easily.

The above-mentioned hosel, shaft case and screw member, preferably, may be made of metal and, more preferably, they may be made of aluminum, titanium, or their alloys. The hosel3, which is produced separately from the head1, may preferably be made of the material that has a specific gravity equivalent to or lower than the head main body2: that is, the hosel3may also be made of, for example, a titanium alloy, aluminum, an aluminum alloy, a magnesium alloy, FRP, or synthetic resin.

The material of the golf club head is not limited to any specific one. However, when the golf club head is of a wood type, it can be made of a titanium alloy, an aluminum alloy, stainless steel or the like.

According to the invention, as described above, by removing the screw member6and spacer7, or by replacing the screw member6and spacer7with another screw member and spacer having different dimensions, the shaft insertion depth is changed. Specifically, by removing or replacing the screw member6and spacer7, the weight and center of gravity of the head can be respectively changed. Thus, according to the invention, preferably, there may be formed a weight adjusting portion in the head. Specifically, there is formed a weight adjusting screw hole in the sole portion, back portion, or side portion of the golf club head, and one of screws having different weights is mounted into the weight adjusting screw hole to thereby adjust the weight of the head. When, for such screws, there are used screws which are different in length and are made of different materials (for example, resin such as nylon, aluminum, magnesium, titanium, their alloys, stainless steel, and tungsten alloy), the weight of the head can be adjusted.

Here, in the illustrated golf club head of a hollow type, due to provision of the hosel3, hosel installation portion2g, shaft case5, and screw members6,8, the weight of the heel side of the head is larger than that of an ordinary golf club head. In view of this, preferably, by increasing the thickness of the toe side or back portion thereof or by providing a weight on the toe side thereof, the golf club head may be balanced well.

Embodiment Shown in FIG.9

According to the invention, as shown inFIG. 9, there may also be used a second screw member8A with the O ring8rremoved therefrom and, instead of the O ring8r, between the inner peripheral surface of the screw member8A and the outer peripheral surface of the shaft4, there may be interposed a thin cylindrical sleeve4smade of elastic material such as rubber or elastomer. The inner peripheral surface of the sleeve4sis contacted with the shaft4, while the outer peripheral surface thereof is contacted with the inner peripheral surface of the screw member8A. The screw member8A has the same shape as the screw member8except that the O ring mounting groove is removed therefrom. The other remaining structures of the embodiment shown inFIG. 9are the same as the embodiment shown inFIG. 3and thus the same parts thereof are given the same designations. In this golf club1A as well, similarly to the above-mentioned golf club1, the shaft insertion depth of the club1A can be changed and the shaft of the club1A can be replaced.

Here, in the inner peripheral surface of the sleeve4s, there may also be formed an uneven portion such as a female screw which is formed in the inner peripheral surface of a nut. In this case, a frictional force between the inner peripheral surface of the sleeve4sand shaft4can be reduced, whereby the sleeve4scan be mounted onto and removed from the shaft4smoothly.

Embodiment Shown in FIG.10

According to the invention, like a head1C shown inFIG. 10, a head main body2C and a hosel3C may be formed as an integral body. The other remaining structures ofFIG. 10are the same as those ofFIG. 3and thus the same parts thereof are given the same designations. InFIG. 10, there is used an O ring8r; however, likeFIG. 9, there may also be used the sleeve4s.

In this embodiment, a first screw member6is threadedly mounted on the upper end of the hosel3, a shaft case5D is inserted through the screw member6into the hosel3, and a second screw member11is threadedly engaged with the screw member6, whereby the shaft case5D is fixed to the hosel3.

The screw member6is the same screw member that is used in the embodiment shown inFIGS. 1 to 8. That is, the lower half portion of the screw member6is formed smaller in diameter than the upper half portion6a, a male screw6bis formed in the outer peripheral surface of the lower half portion, and a female screw6dis formed in the inner peripheral surface of the upper half portion6a. However, according to the present embodiment, as shown inFIG. 12, in the outer peripheral surface of the upper half portion6a, there are formed six plane portions6e, thereby providing a nut-like shape. When a tool such as a monkey wrench or a spanner is applied to these plane portions6e, the screw member6can be rotated.

The screw member11has a substantially ring shape that is substantially the same as the screw member6. The lower half portion of the screw member11is formed smaller in diameter than the upper half portion11athereof and, in the outer peripheral surface of the lower half portion, there is cut formed a male screw11b. According to this embodiment, as shown inFIG. 12, in the outer peripheral surface of the upper half portion11a, there are formed six plane portions11e, thereby providing a nut-like shape. When a tool such as a monkey wrench or a spanner is engaged with these plane portions11e, the screw member11can be rotated. The inner hole of the screw member11is equal in diameter from the upper end to the lower end. In this respect, the screw member11is different in shape from the screw member6. The other remaining portions of the shape of the screw member11are the same as the screw member6.

The shaft case5D used in this embodiment has a length which extends from the bottom of the hosel3to the outside of the hosel3. On the outer peripheral surface of the middle portion of the shaft case5D in the axial direction (longitudinal direction) thereof, there is provided a projecting portion5t. This projecting portion5tis a flange-like portion which extends around the shaft case5. And, the projecting portion5thas a diameter which allows the shaft case5to come into contact with the step surface6mof the screw member6or the step surface3bof the hosel3from above.

Integrally with the upper end of the shaft case5D, there is mounted an umbrella-shaped portion5ghaving a tapered outer peripheral surface the diameter of which decreases as it goes toward its upper end. This umbrella-shaped portion5ghas a circular truncated cone shape and, in the upper surface of the umbrella-shaped portion5g, there is formed a shaft insertion hole5a. The lower surface of the umbrella-shaped portion5gis superimposed on the upper surface of the screw member6through a ring-shaped thin layer member9.

The shaft case5D includes a small diameter portion5hwhich is formed continuously with the lower portion of the umbrella-shaped portion5g. The screw member6is rotatably fitted with the outer surface of the small diameter portion5h. The above-mentioned projecting portion5tis disposed downwardly of the small diameter portion5hof the shaft case5D. The lower end face of the screw member6is contacted with the projecting portion5tthrough a ring-shaped thin layer member9.

The hosel3, spacer7and head main body2used in FIGS.11to13are respectively the same in structure as those used inFIGS. 1 to 8.

To assemble this golf club, similarly to the previously-mentioned embodiment, the leading end of the shaft4is inserted into the shaft insertion hole5aof the shaft case5D with the screw member11connected thereto and is fixed to the insertion hole5ausing an adhesive agent previously. Also, the spacer7is disposed on the bottom of the hosel3and the screw member6is screwed into the hosel3previously.

The shaft case5D of the shaft case/shaft connected unit (in which the shaft case5D is fixed to the shaft4in this manner) is inserted through the screw member6into the hosel hole3H.

After the shaft case5D is inserted into the hosel hole3H in such a direction that the inclined surfaces5cof the shaft case5D and the inclined surfaces7dof the spacer7can be superimposed on top of each other, the male screw11bof the screw member11is threadedly engaged into the female screw6dof the screw member6.

As a result of this, as shown inFIG. 11, the lower end face of the screw member11and the step surface6mof the screw member6hold and press the projecting portion5tof the shaft case5D between them, and the inclined surfaces5cof the shaft case5D are engaged with the inclined surfaces3dof the hosel3through the spacer7respectively, whereby the shaft case5D is fixed to the hosel3. This completes the assembly of the golf club in which the shaft4and head1D are formed as an integral body, because the shaft case5D and shaft4are firmly bonded to each other with the adhesive agent.

To pull out the shaft case5from this golf club, the screw member11may be turned in its loosening direction. Since the male screw11bof the screw member11is threadedly engaged with the female screw6dof the screw member6, when the screw member11turns in the loosening direction, the screw member11moves upwardly (threadedly moves) to push up the umbrella-shaped portion5g, whereby the shaft case5D is moved upwardly. As a result of this, the shaft case5D moves in an upward direction where it parts away from the hosel3, so that the shaft case5D can be easily pulled out from the hosel3.

After removal of the shaft case5D from the hosel3, when the screw member6is removed from the hosel3and the shaft case5D is immediately screwed into the hosel3and the screw member11is threadedly engaged into the female screw3aof the hosel3, as shown inFIG. 13, the shaft4can be inserted into the hosel3deeply. The projecting portion5tis held between and pressed by the lower end face of the screw member11and the step portion3bof the hose3.

Alternatively, by removing the shaft case5D from the state shown inFIG. 11and replacing the screw member6with a screw member having a different length in the axial direction, the insertion length of the shaft4can also be changed.

Here, according to the present embodiment as well, a shaft case with a screw member11of the same type as the shaft case5may be previously fixed to a replacing new shaft using an adhesive agent, and the shaft case/shaft connected unit of the existing golf club may be replaced with the new unit.

In the golf club shown inFIGS. 11 to 13, the umbrella-shaped portion5gis formed to have a taper shape. However, alternatively, there may be formed an increasing diameter portion having a flat flange shape and a ferrule may be mounted on the upper portion of the flange-shaped increasing diameter portion.

In the above embodiments, the golf club is of a wood type. However, the invention can also apply to a golf club of any type such as a utility type, an iron type, or a patter type.