Golf club

A golf club includes: a shaft; a head including a hosel formed with a hosel hole; a shaft case with a substantially tube shape being bonded to a leading end of the shaft, the shaft case being inserted into the hosel hole, the shaft case being fixed to the hosel by a ring-shaped screw member fitted onto an upper portion of the shaft case and detachably screwed into a female screw in an inner circumferential surface of the hosel hole, wherein an outer side surface of a lower side part of the shaft case and a lower side part of the hosel hole have non-circular cross-section shapes.

BACKGROUND

1. Field of the Invention

The present invention relates to a golf club, and particularly to a golf club with a shaft which can be easily replaced.

2. Description of the Related Art

A golf club is made by attaching a head to the leading end side of a shaft. The shaft is provided with a grip attached to the base end portion thereof.

According to a conventional general golf club head, a hosel hole is directly provided in the head, and the shaft is inserted into the hosel hole and bonded by adhesive. In addition, an epoxy adhesive is generally used as the adhesive. When the shaft is replaced, the shaft can be pulled out by heating the hosel portion and destroying the composition of epoxy resin hardener.

JP-A-2010-57554 discloses a golf club with a head attached to the leading end of the shaft, in which a substantially cylindrical shaft case is bonded to the leading end of the shaft, the shaft case is inserted into the hosel from the upper end side of the hosel in the head, and the shaft case is fixed to the hosel by a ring-shaped screw member which is fitted onto the shaft case and detachably screwed into the upper end side of the hosel. The shaft case disclosed in this patent document has a configuration in which only the leading end portion is sharpened to have a V shape and further to the upper side than the leading end portion of the shaft case has a cylindrical shape with a true circle shaped cross-section.

SUMMARY

An object of the present invention is to make it possible to strongly fix a shaft case to a head in a golf club in which the shaft case is bonded to the leading end of a shaft and the shaft case is detachably attached via a screw member as the golf club disclosed in Japanese Unexamined Patent Application No. 2010-57554.

According to an aspect of the invention, there is provided a golf club including: a shaft; a head including a hosel formed with a hosel hole; a shaft case with a substantially tube shape being bonded to a leading end of the shaft, the shaft case being inserted into the hosel hole, the shaft case being fixed to the hosel by a ring-shaped screw member fitted onto an upper portion of the shaft case and detachably screwed into a female screw in an inner circumferential surface of the hosel hole, wherein an outer side surface of a lower side part of the shaft case and a lower side part of the hosel hole have non-circular cross-section shapes.

The non-circular cross-section shapes may be square shapes.

The female screw of the hosel hole may be provided further to a lower part than the upper end of the hosel hole by a predetermined distance.

The golf club may further include: a male screw provided on an outer circumferential surface of the upper end portion of the shaft case; a nut member screwed onto the male screw; and a ring-shaped spacer interposed between the nut member and the screw member, the ring-shaped spacer being provided with a cut portion extending from the inner circumference to the outer circumference.

According to the golf club of the present invention, it is possible to pull out the shaft case from the hosel by loosening the screw member and unscrewing the screw member from the hosel. The shaft can be replaced by inserting a new shaft case and shaft connected body, which is obtained by attaching a shaft case to a shaft in advance, into the hosel and screwing the screw member.

According to the present invention, since the side outer surface of the lower side portion of the shaft case and the lower side portion of the hosel hole respectively have a non-circular cross-section shape, rotation of the shaft case about the axis center of the hosel hole is prevented and the shaft case is strongly attached by causing these non-circular cross-section shape portions to be engaged with each other.

The screw member can be easily screwed since the lower side portion of the screw member is firstly inserted into the hosel hole and made to be in a standing state when the screw member is attached to the hosel hole, by providing the female screw of the hosel hole at a lower position with respect to the upper end of the hosel hole by a predetermined distance, and then the screw member is screwed while rotated.

If a nut member is, screwed onto the upper end portion of the shaft case, and a spacer is made to be interposed between the nut member and the screw member, the sliding resistance at the time of rotating the screw member is lowered, and thereby the screw member can be easily rotated. Since the space does not vibrate at the time of a shot and is slidably fixed if a cut portion ranging from the inner circumference to the outer circumference is provided in this space, it is possible to prevent the screw member from being caught by the nut member when the screw member is rotated in the loosening direction and the nut member is pressed upward, and to thereby easily rotate the screw member.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, description will be made of an embodiment with reference to the drawings.

FIG. 1is a front view of a head of a golf club according to an embodiment, andFIG. 2is a side view of the head of the golf club on the heel side. As shown inFIGS. 1 and 2, this golf club is obtained by attaching a shaft4to a hosel3in a head1via a shaft case5and a screw member6and attaching a nut member7to the upper end portion of the hosel3.

This head1includes a head main body2and the hosel3attached to the head main body2. This head1is a hollow wood type and includes a face portion2a, crown portion2b, a sole portion2c, a toe portion2d, a heel portion2e, and back portion2f.

As shown inFIG. 3, a cylindrical hosel placement portion2gis provided on the heel portion2eside and the face portion2aside of the crown portion2b. This hosel placement portion2ghas a cylindrical shape with an opened upper end and a closed lower end and extends in a coaxial state with the shaft4. The hosel3is inserted into this hosel placement portion2gfrom the upper direction and bonded by appropriate bonding means such as welding, brazing, adhering, shrink-fitting, cool-fitting, or the like. In addition, the hosel may be integrally formed with the head main body. For example, the hosel may be integrally produced with the head main body by casting and processing with a CNC processor in order to enhance its dimensional accuracy.

As shown inFIGS. 4 to 8, the hosel3has a substantially cylindrical shape which is obtained by piercing a hole from the upper end to the lower end in the axial center line direction.

A female screw3ais provided in the hosel hole on the entrance side, that is, in the inner circumferential surface of the hosel on the upper end side. However, a male screw3ais provided a position lower than the uppermost end of the hosel3by a predetermined distance (about 1 to 5 mm, particularly about 2 to 4 mm, for example), and the inner circumferential surface of the hosel between the uppermost end and the male screw3aof the hosel3forms a smooth flat surface3fwith a cylindrical shape (FIGS. 6 to 8). In addition, a tapered surface with a tapered shape may be formed on the uppermost end of the flat surface3f. In this embodiment, this female screw3ais a reverse screw, and the male screw6bof the screw member6which is screwed into this female screw3aand will be described later is also a left-hand screw.

A stepped surface3bis provided in the diameter-reduced direction subsequently to the female screw3a, and to the side further to the inside than this stepped surface3bforms a circular hole portion3mwith a cylindrical shape. In addition, the female screw3ais formed by subjecting a hole surface with the same diameter as that of the circular hole portion3mto screw cutting, the inner diameter of the female screw3portion is greater than that of the circular hole portion3mby the amount corresponding to the screw-cut portion, and the stepped surface3bis formed on the border between the male screw3aand the circular hole portion3m.

The side further to the inside (lower side) than this circular hole portion3mforms a square hole portion3s. Two pairs of slopes3dwhich obliquely intersect with the axial center of the hosel3are provided on the side further to the inside than this square hole portion3s, and the hole bottom portion has a truncated square pyramid shape. The slopes3dand3dfacing each other are symmetrically positioned while interposing the axial center of the hosel3. The distance between the slopes3dand3dfacing each other, that is, the interval in the direction perpendicular to the axial center line of the hosel decreases as it approaches the lower end side of the hosel. The intersecting angle θ (FIG. 7(a)) between the slopes3dand3dfacing each other preferably ranges from 10 to 30° and particularly from 15 to 20°.

As shown inFIGS. 6 and 7, the shaft case5is a substantially tube-shaped member in which the upper portion has a cylindrical shape and the lower portion has a square tube shape, and the shaft case5is provided with a hole5afrom the upper end side to the lower end side for inserting the shaft4. The length of the shaft case5is preferably not less than 30 mm, from 40 to 60 mm, for example, and particularly from about 45 to 55 mm. It is preferable that the shaft case5protrudes from the hosel3by 10 to 30 mm, particularly by about 15 to 20 mm in the state of being inserted into and fixed to the hosel3.

A female screw opening is provided so as to penetrate from the inside bottom surface of the hole5ato the lower end surface of the shaft case5, and a weight material10is screwed into this female screw opening.

The depth of the hole5apreferably ranges from 20 to 50 mm, particularly from 25 to 40 mm.

A convex portion5tis provided on the outer circumferential surface of the shaft case5in the middle of the direction of the axial center line of the tube (longitudinal direction). In this embodiment, the convex portion5thas a flange shape which surrounds the shaft case5. This convex portion5thas a diameter which comes in contact with the stepped surface3bfrom its upper side.

The side of the shaft case5further up than the convex portion5tforms a cylindrical shape, and a male screw5nis provided on the outer circumferential surface of its upper side. The part on to the side lower than the convex portion5tforms a square tube portion5s.

The distance from the upper end to the convex portion5tof the shaft case5preferably ranges from 10 to 30 mm, particularly from about 15 to 20 mm.

Two pairs of slopes5care provided on the outer surface of the shaft case5on the lower end side so as to form a truncated square pyramid shape. The slopes5cand5cfacing each other are symmetrically provided while interposing the axial center line of the shaft case5. The distance between the slopes5cand5cfacing each other, that is, the interval in the direction perpendicular to the axial center line of the shaft case5decreases as it approaches the lower end side of the shaft case. The intersecting angle between the slopes5cand5cfacing each other is the same as the intersecting angle θ between the slopes3dand3dof the hosel3. The size of the slope5cof the shaft case5may be the same as that of the slope3dof the hosel3and may be slightly smaller when an elastic body is interposed.

Although not shown in the drawings, a configuration is also applicable in which a chamfer with an angle of about 20 to 45° is formed in the inner circumferential edge of the shaft case5on the upper end side in order to make it easier to insert the shaft4.

The screw member6has a substantially ring shape in which the lower half portion has a smaller diameter as compared with the upper half portion6a, and a male screw6bis carved on the outer circumferential surface of the lower half portion. A tool engaging portion6eis provided on the outer circumferential surface of the upper half portion6aon the upper end side and forms a nut shape.

The lower half portion of the screw member6has a diameter with which the male screw6bis screwed into the female screw3aof the hosel3. The screw member6includes an opening6cpenetrating in the axial center line direction. The diameter of this opening6cis very slightly larger than the diameter of the cylinder-shaped portion of the shaft case5further to the upper side than the convex portion5t, and the screw member6is slidably fitted onto the portion of the shaft case5further up than the convex portion5.

As shown inFIGS. 3 and 7, ring-shaped spacers (a thin spacer made of an elastic body such as rubber, elastomer, or the like)6fand6gare interposed between the lower end surface of the upper half portion6aof the screw member6and the upper end surface of the hosel3and between the lower end surface of the lower half portion6band the upper surface of the convex portion5t.

In this embodiment, a nut member7is provided on the upper side of the screw member6. A female screw7ainto which the male screw5nof the shaft case5is screwed (FIG. 7A) is provided on the inner circumferential surface of the nut member7. The male screw5nand the female screw7aare proper screws.

As shown inFIGS. 3 and 7Ato7F, a thin spacer7fmade of an elastic body such as rubber, elastomer, or the like, plastic, or metal is interposed between the nut member7and the screw member6. This spacer7fhas a flat ring shape and is provided with a cut portion extending from the inner circumferential edge to the outer circumferential edge at a portion in the circumferential direction. Since the spacer does not vibrate and is slidably fixed by providing this cut portion, it is possible to prevent the screw member6from being caught by the nut member7when the screw member6is rotated in the loosening direction and the nut member7is pressed upward, and to thereby smoothly rotate the screw member6.

When a golf club is assembled, the nut member7and the screw member6are fit from the leading end side of the shaft4, and the shaft case5is bonded to the leading end of the shaft4with the use of adhesive as shown inFIG. 4. Preferably, the outer circumferential surface of the leading end portion of the shaft4is coated with this adhesive, and the shaft4is inserted up to the furthest portion of the hole5aof the shaft case5. As the adhesive, an epoxy adhesive or the like is preferably used. In addition, since the air within the hole5ais removed if the weight material10is detached when the shaft4is inserted, the shaft4can be easily inserted.

The shaft case5in a shaft case and shaft connected body, in which the nut member7and the screw member6are fitted and inserted and the shaft case5is bonded as described above, is inserted into the hosel3of the head1as shown inFIG. 4.

As shown inFIG. 5A, the shaft case5is inserted into the hosel3, the square tube portion5sand the square hole portion3sare engaged with each other, and the slope5cand the slope3dare superposed on each other.

The convex portion5tis engaged with the stepped surface3b. Then, the male screw6bof the screw member6is screwed into the female screw3aof the hosel3, and the nut member7is then screwed onto the male screw5aof the shaft case5as shown inFIG. 5B.

At this time, since the flat portion3fis provided on the upper side of the female screw3a, the screw member can be easily screwed into the hosel3while the screw member6is rotated, after the lower end side of the screw member6is inserted to the flat portion3fso as to cause the screw member6to be in the standing state.

Thus, the lower end surface of the screw member6presses the upper surface of the convex portion5tof the shaft case5, the slope5cof the shaft case5is pressed onto the slope3dof the hosel3, and the shaft case5is fixed to the hosel3as shown inFIG. 3. The shaft case5and the shaft4are strongly adhered with the adhesive, and therefore, a golf club in which the shaft4and the head1are integrally provided is completed.

In this embodiment, the screw member6is fitted onto the shaft case5and screwed into the hosel3, the nut member7is screwed into the outer circumference of the upper end of the shaft case5, and the screw member6and the nut member7do not contact with the shaft4when rotated. Accordingly, it is possible to prevent the shaft4from being damaged.

When the shaft case5is pulled out from this golf club, the screw member6is rotated in the loosening direction while the nut member7is maintained in an attached state. Since the male screw6bof this screw member6is screwed into the female screw3aof the hosel3, the screw member6moves upward (advances by screwing) and presses up the nut member7if the screw member6is rotated in the loosening direction. The nut member7is bonded to the shaft case5, and therefore, the nut member7and the shaft case5integrally move upward when the nut member7is pressed up by the screw member6. With such a configuration, the shaft case5can be easily detached since it moves to the upper direction in which the shaft case5is separated from the hosel3.

According to this golf club, high strength and rigidity for the attachment of the shaft4and the shaft case5can be achieved since the shaft case5to which the shaft4is attached is inserted into the hosel3and fixed with the screw member6. In addition, since the square tube portion5sof the shaft case5is made to be engaged with the square hole portion3sof the hosel3and the slopes3dand5care engaged with each other, less slipping occurs, and the rotation of the shaft4about a direction around the axial center of the shaft is prevented. That is, high fixing rigidity of the shaft4in the torque direction can be achieved.

When the shaft of the golf club is to be replaced, the same shaft case as the above-mentioned shaft case5is bonded to a new shaft, with which the existing shaft is to be replaced, in advance with the adhesive. In addition, the nut member7and the screw member6are also attached to this shaft.

The screw member6of the existing golf club is detached, and the old shaft4, the old shaft case5, the nut member7, and the screw member6are detached from the head1together. Subsequently, a new shaft with a shaft case, a top member, and a screw member (shaft case and shaft connected body) is inserted into the head1and fixed with the screw member6and the nut member7.

As described above, it is possible to perform attachment and replacement of the shaft very easily and rapidly. Conventionally, it took several hours to about a day to replace the shaft since the hosel portion of the existing golf club was heated to destroy the composition of the adhesive hardener, the shaft was pulled out, and a new shaft was then bonded with adhesive. However, it is possible to replace the shaft in several minutes by attaching the shaft case5to the new shaft with adhesive in advance in the embodiment. Accordingly, it is possible to implement a usage style in which different shafts are sequentially attached to the same head main body for trial shots by preparing the shafts of various specifications, to each of which the shaft case is attached.

In addition, the shaft case5can be easily inserted into the hosel3since the leading end side of the shaft case5is made to have a tapered shape by providing two pairs of slopes5c.

It is preferable that the hosel, the shaft case, and the screw member are made of metal, particularly, aluminum, titanium, or an alloy thereof. The nut member7is preferably made of aluminum or synthetic resin. The hosel3which has a separate body from the head1is preferably made of a material with a specific gravity equivalent to or lower than that of the head main body, and titanium alloy, aluminum, aluminum alloy, magnesium alloy, FRP, synthetic resin or the like may be used, for example.

Although the material of the head is not particularly limited, titanium alloy, aluminum alloy, stainless, or the like may be used, for example, in the case of a wood type golf club head.

In the above embodiment, since the circular hole portion3mis provided on the side further to the inside (lower side) than the stepped surface3bof the hosel3, and a gap portion is formed between the inner circumferential surface of this circular hole portion3mand the shaft case5, the weight of the hosel3is lightened by the amount corresponding to the gap portion. The inner diameter of the circular hole portion3mis preferably longer than the outer diameter of the cylindrical shape portion of the upper portion of the shaft case5by 0.2 to 5.0 mm, particularly by 1.0 to 3.0 mm. The length (depth) of the circular hole portion3mpreferably ranges from 1 to 8 mm, and particularly from 3 to 6 mm.

Although the square hole portion3sand the square tube portion5swith quadrate shapes are provided in the hosel3and the shaft case5in the above embodiment, the cross-section may have a rectangular shape, a trapezoidal shape, or the like or may have a non-circular shape other than the square shape. Examples of the non-circular cross-section shapes include a polygonal shape such as a hexagonal shape or the like, a star shape, a gear shape, an oval shape, a shape obtained by cutting a part of a circle in the chord direction, and the like.FIG. 9is a cross-sectional view of the hosel3′ including a square hole portion3swith a rectangular cross-sectional shape, andFIG. 10is a cross-sectional view of the hosel3″ including the square hole portion3swith a trapezoidal cross-section, each of which shows the cross-section of the same part as that shown inFIG. 7F.

In addition, a grip to be attached to the shaft4, which has a non-circular cross-section, is used in some cases. For example, the lower side surface in the outer circumferential surface of the grip, which directs the ground in the address state, is made to have a shape protruding as compared with the other surfaces. In such a case, the shaft can be attached to the head such that the grip protruding portion reliably directs the ground side by setting the direction of the shaft case5in the circumferential direction corresponding to the grip protruding portion when the shaft case5is attached to the shaft4.

An example of such a grip with a non-true-circular cross-section will be shown inFIGS. 12 to 16, and the golf club in which this grip is attached to the golf club head1will be shown inFIG. 11.

In addition,FIG. 12is a side view of the grip9,FIG. 13is a vertical cross-sectional view of the grip9in the longitudinal direction,FIG. 14is a cross-sectional view taken along XIV-XIV line inFIG. 13,FIG. 15is an enlarged view ofFIG. 14, andFIG. 16is an enlarged cross-sectional view taken along XVI-XVI line inFIG. 11.

As shown inFIG. 11, the leading end of the shaft4is inserted into the hosel of the head1and fixed with the adhesive.

The grip9has a substantially tube shape including an inserting hole9bfor the shaft4and is made of rubber or the like. This grip9is provided with a thick portion9ain a part (the lower side inFIG. 11) in its circumferential direction. This thick portion extends in the longitudinal direction of the grip9. This thick portion9ais provided such that the sectional shape of the inner circumferential surface of the grip9(sectional shape in the direction perpendicular to the longitudinal direction of the grip9) becomes a chord shape. When the shaft4is inserted into this grip9, the thick portion9ais pressed outward from the inner side, the outer circumference protrudes, and the convex ridge portion9cis formed as shown inFIG. 16. This convex ridge portion9cextends in the longitudinal direction of the grip9(in the longitudinal direction of the shaft4). The shaft case and shaft connected body is configured by attaching the shaft case5to the shaft4such that this convex ridge portion9cis positioned so as to direct the lower side, that is, the side facing the ground when the golf club is in the address state. With such a configuration, the convex ridge portion9cis always correctly positioned on the ground side in the address state even if any shaft case and shaft connected body is attached to the head1. It is possible to correctly position the convex ridge portion9con the ground side when the hosel and the shaft case with the sectional shapes shown inFIGS. 9 and 10, particularly inFIG. 10are used.

Although the golf club head is a wood type in the above embodiment, the present invention can also be applied to any type of golf club head including a utility type, an iron type, a putter, and the like.

In the case of a hollow type golf club head shown in the drawings, the weight on the heel side is heavier as compared with a general golf club head since the hosel3, the hosel placement portion2g, the shaft case5, and the screw member6are provided. Accordingly, it is preferable to configure the toe side or the back portion to be thicker or provide a weight on the toe side in order to keep a good balance for the golf club head.