US20110256952A1

Movatterモバイル変換

Info

Publication number: US20110256952A1
Application number: US13/091,769
Authority: US
Inventors: Fumiaki Sato; Hiroshi Takahashi; Hideo Matsunaga
Original assignee: Bridgestone Sports Co Ltd
Current assignee: Bridgestone Sports Co Ltd
Priority date: 2008-09-01
Filing date: 2011-04-21
Publication date: 2011-10-20

Abstract

A method for replacing a shaft of a golf club, the golf club including: a head having a hosel; the shaft; a shaft case fixed to one end of the shaft, and configured to be inserted into the hosel; and a ring-shaped screw member configured to be screwed into one end of the hosel to fix the shaft case in the hosel, and to be fitted with an outer face of an one end of the shaft case, the ring-shaped screw member being noncontact with the shaft, the method comprising: fixing a newly-provided shaft to a newly-provided shaft case corresponding to the hosel; unscrewing the ring-shaped screw member from the hosel; removing the shaft case with the shaft from the hosel; inserting the newly-provided shaft case with the newly-provided shaft to the hosel; and screwing the ring shaped screw member on the hosel.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No. 12/338,533 filed on Dec. 18, 2008, which is based upon and claims the benefit of priority from Japanese Patent Application No. 2008-223644, filed Sep. 1, 2008, the entire contents of which are incorporated herein by reference.

BACKGROUND

1. Field

The present invention relates to a golf club and, specifically, it relates to a golf club which is capable of replacing a shaft easily. Also, the invention relates to a method for replacing the shaft of the golf club.

2. Description of the Related Art

A golf club includes a shaft and a head mounted on the leading end portion of the shaft. A grip is mounted on the base end portion of the shaft.

In a conventional ordinary golf club head, a hosel hole is formed directly in the head, and a shaft is inserted into the hosel hole and is fixed to the golf club head using an adhesive. Here, as the adhesive, there is generally used an epoxy-system adhesive. For replacement of the shaft, the hosel hole portion of the golf club head may be heated to destroy the structure of the hosel hole portion made of hardened epoxy resin, whereby the shaft can be pulled out.

In JP-A-11-178954, there is disclosed a golf club head structured such that a head main body and a hosel are provided separately from each other and the hosel is fixed to the head main body using a screw. According to the structure of the golf club head disclosed in the Japanese Patent Publication Hei-11-178954, a plate-shaped neck portion is formed on the lower end side of the hosel, while the neck portion is inserted into the insertion portion of the head main body and is then fixed to the head main body using a screw. By fixing the plate-shaped neck portion to the head main body in this manner, when hitting a golf ball with the golf club, that is, at the impact time, the neck portion is caused to bend to thereby relieve the concentration of stresses that are generated in the connecting portion between the shaft and hosel.

In the golf club head disclosed in JP-A-11-178954, the connecting strength and rigidity of the head main body and hosel are short, thereby being unable to provide a strong feeling of impact. Also, the position of the hosel is excessively high.

SUMMARY OF THE INVENTION

A golf club according to the invention is a golf club having a head mounted on the leading end of a shaft, in which a substantially cylindrical-shaped shaft case is fixed to the leading end of the shaft, the shaft case is inserted into a hosel formed in the head from the upper end side of the hosel, the shaft case is fixed to the hosel by a ring-shaped screw member fitted with the outer surface of the shaft case as well as removably and threadedly engaged with the upper end side of the hosel, and the screw member is disposed on the outer periphery of the shaft case in such a manner that it is not in contact with the shaft.

A golf club according to the invention is a golf club according to one embodiment, in which the shaft case includes a projecting portion on the outer peripheral surface of the middle portion thereof existing in the axial direction of the cylindrical shape thereof, the head includes a head main body and the hosel fixed to the head main body, a female screw is cut formed on the inner peripheral surface of the upper end side of the hosel, a male screw is cut formed on the outer peripheral surface of the screw member, the male screw is threadedly engaged with the female screw of the hosel to thereby threadedly engage the screw member with the hosel, and the lower end face of the screw member is pressed against the projecting portion downwardly to thereby fix the shaft case to the shaft.

A golf club according to the invention is a golf club according one embodiment, in which the shaft case includes a small diameter portion on the outer peripheral surface of the middle portion thereof existing in the axial direction of the cylindrical shape thereof, the lower portion of the shaft case than the small diameter portion is formed as a large diameter portion, a lower-side step surface is interposed between the small and large diameter portions, the upper portion of the shaft case than the small diameter portion is formed as an enlarged-diameter portion, an upper-side step surface is interposed between the small diameter portion and enlarged-diameter portion, the head includes a head main body and the hosel fixed to the head main body, a female screw is cut formed on the inner peripheral surface of the upper end side of the hosel, a male screw is cut formed on the outer peripheral surface of the screw member, the male screw is threadedly engaged with the female screw of the hosel to thereby threadedly engage the screw member with the hosel, the lower end face of the screw member is pressed against the lower-side step surface downwardly to thereby fix the shaft case to the shaft, and the upper end face of the screw member is pressed against the upper-side step surface to thereby be able to prevent the shaft case from being removed from the hosel.

A golf club according to the invention is a golf club according to one embodiment, in which an elastic member is provided on the lower side of the screw member.

A golf club according to the invention is a golf club according to any one of embodiments, in which the shaft case is made of a cylindrical member having its lower end side closed with its upper end side opened, and the shaft is inserted into the shaft case and is fixed thereto using an adhesive.

A golf club according to the invention is a golf club according to one embodiment, in which at least the lower end side of the shaft case is formed as a non-circular section shape portion and, at least on the lower end side of the hosel, there is formed a non-circular section shape portion with which the leading end side of the shaft case is engaged.

A golf club according to the invention is a golf club according to one embodiment, in which the non-circular section shape portion of the shaft case is formed of an inclined surface obliquely intersecting with the center axis of the shaft case, and the non-circular section shape portion of the hosel is formed of an inclined surface obliquely intersecting with the center axis of the hosel.

A golf club according to the invention is a golf club according to any one of embodiments, in which an elastic member is interposed between the lower end side of the shaft case and the inner surface of the hosel.

A golf club according to the invention is a golf club according to any one of embodiments, a grip is mounted on the shaft, and the grip includes a projecting portion extending in the longitudinal direction of the shaft.

A method according to the invention is a method for replacing the shaft of a golf club as set forth in any one of embodiments with a new shaft, comprising the steps of: previously fixing a new shaft to a shaft case of the same type as the shaft case to form a new shaft case/shaft connected assembly; and, removing an old shaft case/shaft connected assembly currently mounted on the golf club from the head of the golf club and then mounting the new shaft case/shaft connected assembly onto the golf club head. Further, A method according to the invention is a method for replacing a head, of a golf club as set forth in any one of embodiments with a new head, including: the steps of: unscrewing the ring-shaped screw member from the hosel; removing the shaft case with the shaft from the hosel; providing a new head having a new hosel; inserting the shaft case with the shaft to the new hosel; and screwing the ring shaped screw member on the new hosel.

In a golf club and a shaft replacing method according to the invention, when the screw member is loosened and removed, the shaft case can be pulled out from the hosel. Specifically, a new shaft case/shaft connected assembly, in which a new shaft has been previously mounted on a shaft case, may be inserted into the hosel, and the screw member may be then threadedly mounted onto the assembly, whereby the currently used or old shaft can be replaced with the new shaft.

According to the invention, since the shaft case is inserted into the cylindrical-shaped hosel and is fixed to the hosel using the screw member, the mounting of the shaft case on the hosel can be made firm.

According to the invention, since the screw member is disposed on the outer periphery of the shaft case but is not in contact with the shaft, even when the screw member is rotated, the screw member will never rub against the shaft, thereby being able to prevent the shaft against damage.

Conventionally, after the adhesive is heated to thereby destroy the structure thereof, a currently used shaft is removed and a new shaft is then mounted using the adhesive again. This takes troublesome labor and time. On the other hand, the invention can save such troublesome labor and time. Owing to this, just after the shaft is removed from the head of the golf club used for a ball hitting test, another shaft of different characteristics can be mounted onto the head of the golf club for another hitting test. This makes it possible to a golfer to find out a proper golf club in a golf shop very easily.

According to a golf club in the invention, when the screw member is screwed into the upper end side of the hosel, the lower end of the screw member is pressed against the projecting portion of the shaft case (in a golf club according to an embodiment) or the lower-side step surface of the shaft case (in a golf club according to an embodiment), whereby the shaft case can be fixed. In a golf club according to an embodiment, when the screw member is rotated reversely, the screw member is pressed against the upper-side step surface of the shaft case upwardly, whereby the shaft case can be removed from the hosel.

According to a golf club in the invention, generation of rickety motion between the screw member and the projecting portion of the shaft case can be prevented.

According to a golf club in the invention, the shaft can be inserted into the deep portion of the shaft case and can be thereby adhered to the shaft case firmly.

According to a golf club in the invention, the peripheral direction positioning of the shaft case can be carried out. Also, the head and shaft case can be prevented against rotation with respect to each other. Here, preferably, there may be formed non-circular section shape portions in the shaft case and hosel respectively. In this case, when the grip includes a projecting portion, the projecting portion can be positioned accurately in the surface that, when a golfer holds the golf club for addressing a golf ball, faces the ground.

According to a golf club in the invention, the shaft case can be easily inserted into the hosel.

According to a golf club in the invention, shocks and vibrations generated between the shaft case and the inner surface of the hosel can be absorbed.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is an exemplary front view of a head according to a first embodiment of the invention.

FIG. 2 is an exemplary side view of the heel side of the head.

FIG. 3 is an exemplary section view taken along the III-III line shown inFIG. 1.

FIG. 4 is an exemplary perspective view of the head, showing how to mount and replace a shaft.

FIGS. 5A and 5B are exemplary perspective views of the head, showing how to mount and replace the shaft of the head.

FIG. 6 is an exemplary perspective view of a hosel, a shaft case and a screw member used in the first embodiment.

FIG. 7 is an exemplary section view of the above-mentioned hosel, shaft case and screw member.

FIG. 8 is an exemplary perspective section view of the hosel.

FIGS. 9A and 9B are exemplary section views of a shaft case according to a second embodiment of the invention.

FIG. 10 is an exemplary front view of a golf club according to the second embodiment of the invention.

FIG. 11 is a section view of a grip shown inFIG. 10.

FIG. 12 is an exemplary section view of the grip.

FIG. 13 is a section view taken along the XIII-XIII line shown inFIG. 12.

FIG. 14 is an enlarged view ofFIG. 13.

FIG. 15 is an enlarged section view taken along the XV-XV line shown inFIG. 10.

FIG. 16 is an exemplary front view of a head according to a third embodiment of the invention.

FIG. 17 is an exemplary side view of a head according to a fourth embodiment of the invention.

FIG. 18 is an exemplary section view of a head according to a fifth embodiment of the invention.

FIG. 19 is an exemplary perspective view of a hosel, a shaft case and a screw member according to a sixth embodiment of the invention.

FIG. 20 is an exemplary section view of the head shown inFIG. 19.

FIG. 21 is an exemplary section view of a head according to a seventh embodiment of the invention.

FIG. 22 is an exemplary exploded perspective view of the head shown inFIG. 21.

FIG. 23 is an exemplary section view taken along the XXIII-XXIII line shown inFIG. 22.

FIG. 24 is an exemplary section view of a head according to an eighth embodiment of the invention.

FIG. 25 is an exemplary exploded perspective view of the head shown inFIG. 24.

FIG. 26 is an exemplary section view taken along the XXVI-XXVI shown inFIG. 25.

FIG. 27 exemplary shows relation between EI values and measurement sites of two shafts.

DETAILED DESCRIPTION

Now, description will be given below of embodiments according to the invention with reference to the accompanying drawings. Specifically,FIG. 1 is a front view of a golf club head according to a first embodiment of the invention.FIG. 2 is a side view of the heel side of the golf club head.FIG. 3 is a section view taken along the III-III line shown inFIG. 1.FIGS. 4 and 5(A),5B are respectively perspective views of the golf club head, showing how to mount and replace the shaft of the golf club head.FIG. 6 is a perspective of a hosel, a shaft case, a screw member and a top portion.FIG. 7 is a section view of the hosel, shaft case, screw member and top portion.FIG. 8 is a sectional perspective view of the hosel.

In this golf club, ashaft4 is mounted on thehosel3 of ahead1 through ashaft case5 and ascrew member6.

Thehead1 includes a headmain body2 and ahosel3 mounted on the headmain body2. Thishead1, which is of a hollow wood type, includes aface portion2a, acrown portion2b, asole portion2c, atoe portion2d, aheel portion2eand aback portion2f.

As shown inFIG. 3, in theface portion2aside andheel portion2eside of thecrown portion2b, there is formed a cylindrical-shapedhosel installation portion2g. Thehosel installation portion2ghas a cylindrical shape the upper end of which is open and the lower end of which is closed, and also thehosel installation portion2gextends coaxially with theshaft4. Thehosel3 is inserted into thehosel installation portion2gfrom above and is fixed by proper fixing means such as by welding, by brazing, by adhesion, by shrinkage fit, or by expansion fit. However, alternatively, as shown inFIG. 18 which will be discussed later, the hosel may also be formed integrally with the head main body. For example, the hosel may be formed integrally with the head main body by casting and, in order to enhance the dimension precision thereof, it may be then worked using a CNC working machine.

As shown inFIGS. 6 to 8, thehosel3 has a substantially cylindrical shape in which there is opened up a hole extending in the axial direction thereof from the upper end thereof toward the lower end thereof.

In the entrance side of the hole, that is, in the inner peripheral surface of the upper end side of the hosel, there is formed afemale screw3a. In this embodiment, thisfemale screw3ais a reverse screw, while amale screw6bformed in a screw member6 (which will be discussed later) and threadedly engageable with thefemale screw3ais also a reverse screw.

Continuously with thefemale screw3a, specifically, in the diameter-reducing direction of thehosel3, there is formed astep surface3b; and, the deeper side of thehosel3 than thestep surface3bis formed as acylindrical portion3c. In the deeper side of thehosel3 than thecylindrical portion3c, there are formed a pair of

inclined surfaces

3dand3dwhich respectively intersect obliquely with the axis of thehosel3. The

inclined surfaces

3d,3dare arranged symmetrically with the axis of thehosel3 between them. The distance between the two

inclined surfaces

3d,3d, that is, the spacing thereof in the direction perpendicular to the hosel axial line decreases as it goes toward the lower end side of thehosel3. The angle of intersection θ(FIG. 7) between the

inclined surfaces

3d,3d, preferably, may be set for 10 to 30°, more preferably, for 15 to 20°.

As shown inFIGS. 6 and 7, theshaft case5 is a cylindrical member having a diameter slightly smaller than the diameter of thecylindrical portion3cof thehosel3; and theshaft case5 has ahole5awhich extends from the upper end side thereof toward the lower end side thereof and also into which theshaft4 can be inserted. The length of theshaft case5 may preferably be 30 mm or more, for example, 40 to 60 mm, more preferably, about in the range of 45 to 55 mm. In a state where theshaft case5 is inserted into and fixed to thehosel3, theshaft case5 may preferably project from thehosel3 by 10 to 30 mm, more preferably, by 15 to 20 mm.

In theshaft case5, there is opened up asmall hole5bserving as an air bleeder which extends from the deep bottom surface of thehole5ato the lower end face of theshaft case5. Here, the cylindrical portion of thehole5aof theshaft case5, preferably, may extend up to (deeper than) a position where theinclined surfaces3dare formed. In the present golf club, when hitting the ball, the inclined surfaces receive the hitting impact. Therefore, the present golf club can provide a similar hitting feeling to an ordinary golf club in which a head and a shaft are fixed together using an adhesive.

Theshaft case5 includes a projectingportion5tformed on the outer peripheral surface of the middle portion of the cylindrical shape of theshaft case5 in the axial direction (longitudinal direction) thereof. In the present embodiment, the projectingportion5tis formed as a flange-shaped portion which is wound around theshaft case5. The projectingportion5thas a diameter which allows the projectingportion5tto be contacted with thestep portion3bfrom above.

Theshaft case5 includes amale screw5nformed on the outer peripheral surface of the upper portion thereof.

The depth of the cylindrical portion of thehole5afor connection with the shaft may preferably be in the range of 20 mm to 50 mm, more preferably, in the range of 25 mm to 40 mm.

The distance from the upper end of theshaft case5 to the projectingportion5tmay preferably be about in the range of 10 mm to 30 mm, more preferably, in the range of 15 mm to 20 mm.

On the outer surface of the lower end side of theshaft case5, there are provided a pair of

inclined surfaces

5cand5c. These

inclined surfaces

5cand5care arranged symmetrically with the axial line of theshaft case5 between them. The distance between the

inclined surfaces

5cand5c, that is, the spacing thereof in the direction perpendicular to the axial line of theshaft case5 decreases as it goes toward the lower end side of theshaft case5. The angle of intersection θbetween the

inclined surfaces

5cand5cis the same as the angle of intersection θbetween the

inclined surfaces

3dand3dof thehosel3. The size of theinclined surface5cof theshaft case5 may be the same as theinclined surface3dof thehosel3, or, when an elastic member is interposed between theinclined surfaces5c, the size of theinclined surface5cmay be slightly smaller than that of theinclined surface3d.

Although not shown, the inner peripheral edge of the upper end side of theshaft case5 may be chamfered about at an angle of 20 to 45° to thereby facilitate the insertion of theshaft4.

Thescrew member6 has a substantially ring-like shape; the lower half section of thescrew member6 is smaller in diameter than the upper half section thereof; and, on the outer peripheral surface of the lower half section of thescrew member6, there is formed amale screw6b. The outer peripheral surface of the upper end side of theupper half section6aincludes sixplane portions6eand provides a nut-like shape.

The lower half section of thescrew member6 has a diameter which allows themale screw6bto be threadedly engaged with thefemale screw3aof thehosel3. Thescrew member6 includes ahole6cwhich penetrates therethrough in the axial direction thereof. The diameter of thishole6cis set slightly larger than the diameter of the upper portion of theshaft case5 than the projectingportion5tthereof, while thescrew member6 is slidably fitted with the outer surface of the upper portion of theshaft case5 than the projectingportion5tthereof.

Between the lower end face of theupper half section6aof thescrew member6 and the upper end face of thehosel3 as well as between the lower end face of thelower half section6band the upper surface of the projectingportion5t, as shown inFIG. 3, there are interposed ring-shaped spacers (for example, spacers respectively composed of an elastic member which is made of rubber, an elastomer or the like)6fand6grespectively.

According to the present embodiment, upwardly of thescrew member6, there is provided atop portion7. Thistop portion7 has a tapered ring-like shape the outer peripheral surface of which reduces in diameter as it goes upwardly. On the inner peripheral surface of thetop portion7, there is formed afemale screw7awhich can be threadedly engaged with themale screw5nof theshaft case5. On the lower end side of the outer peripheral surface of thetop portion7, there are formed a pair ofparallel surfaces7e. Owing to this, a tool can be engaged with theparallel surfaces7eto thereby rotate thetop portion7. Between thetop portion7 and screwmember6, there is formed a clearance which can be used to rotate thescrew member6; however, there may also be interposed between them athin spacer7fmade of an elastic member such as rubber or an elastomer, or plastic, or metal. Here, thetop portion7 may also be fixed to theshaft case5 by welding, by adhesion, by caulking or by similar proper means. Also, since thetop portion7 is used to allow thescrew member6 to rotate and also to prevent thescrew member6 from slipping off theshaft case5, as shown inFIGS. 21 to 23 (which will be discussed later), thetop portion7 may also be formed integrally with a hosel case.

To assemble this golf club, as shown inFIG. 4, thetop portion7 and screwmember6 may be fitted with each other from the leading end side of theshaft4, and theshaft case5 may be previously fixed to the leading end of theshaft4 using an adhesive. Preferably, the adhesive may be applied to the outer peripheral surface of the leading end portion of theshaft4, and theshaft4 may be inserted down to the deeper-most portion of thehole5aof theshaft case5.

Since theshaft case5 includes thesmall hole5b, when theshaft4 is inserted into thehole5aof theshaft case5, the air is allowed to flow out through thesmall hole5b. As the adhesive, there may preferably be used an epoxy-system adhesive.

Theshaft case5 of a shaft case/shaft connected assembly, in which thetop portion7 and screwmember6 are fitted with each other and theshaft case5 is fixed in this manner, is inserted into thehosel3 of thehead1 as shown inFIG. 4. Here, according to the present embodiment of the invention, thin-piece-shapedelastic members8 respectively made of rubber, an elastomer or the like and having a small thickness (for example, a thickness of about 0.5 mm to 5 mm) have been previously applied onto the

inclined surfaces

5c,5cof theshaft case5 and also onto the leading end face of theshaft case5 by welding or by adhesion. Theelastic members8 may also have been provided on theshaft case5 previously, or may also be provided after the shaft case/shaft connected assembly is formed.

As shown inFIGS. 5A and 5B, theshaft case5 is inserted into thehosel3; and, the inclines

surfaces

5c,5cand

inclined surfaces

3d,3dare superimposed on top of each other. Next, as shown inFIG. 5B, themale screw6bof thescrew member6 is screwed into themale screw3aof thehosel3 and, after then, thetop portion7 is screwed into themale screw5aof theshaft case5.

As a result of this, as shown inFIG. 3, the lower end face of thescrew member6 is pressed against the upper surface of the projectingportion5tof theshaft case5, theinclined surfaces5cof theshaft case5 are pressed against theinclined surfaces3dof thehosel3 through theelastic members8, and theshaft case5 is fixed to thehosel3. This completes a golf club in which theshaft4 andhead1 are unified as an integral body, since theshaft case5 andshaft4 are firmly bonded to each other by the adhesive.

According to the present embodiment, thescrew member6 is fitted with the outer surface of theshaft case5 and is screwed into thehosel3, and thetop portion7 is screwed into the outer periphery of the upper end of theshaft case5; and, when thescrew member6 andtop portion7 are rotated, they are prevented from touching theshaft4. This can prevent theshaft4 against damage.

To pull out theshaft case5 from the golf club, in a state where thetop portion7 is fixed to theshaft case5, thescrew member6 may be turned in the loosening direction thereof. Since themale screw6bof thescrew member6 is in threaded engagement with the female screw of thehosel3, when thescrew member6 is turned in the loosening direction, thescrew member6 is moved (threadedly moved) upwardly to thereby push up thetop portion7. Since thetop portion7 is fixed to theshaft case5, when thetop portion7 is pushed upwardly by thescrew member6, thetop portion7 andshaft case5 are moved upwardly as an integral body. This moves the shaft case in the upward direction where it can be removed from thehosel3, thereby being able to remove theshaft case5 from the golf club easily.

In this golf club, since theshaft case5 with theshaft4 is inserted into and is fixed to thehosel3 using thescrew member6, the mounting strength and rigidity of theshaft4 andshaft case5 are enhanced.

Also, after thescrew member6 is screwed into thefemale screw3aof thehosel3, thetop portion7 is screwed into themale screw5nof theshaft case5, thereby being able to prevent thescrew member6 from loosening. Specifically, according to the present embodiment, thefemale screw3aandmale screw6bare respectively reverse screws as well as the loosening rotation direction of thescrew member6 provides the tightening rotation direction of thetop portion7, thereby being able to prevent the loosening of thescrew member6.

Here, as shown inFIG. 3, since there are interposed the thin-piece-shapedelastic members8 made of rubber, an elastomer or the like between theinclined surfaces3dof thehosel3 and theinclined surfaces5cof theshaft case5, shocks and vibrations at the impact time can be absorbed.

To replace the shaft of the golf club, a shaft case of the same type as theshaft case5 may have been previously fixed to a new shaft to be substituted. Here, thetop portion7 and screwmember6 may also have been mounted on this shaft previously.

Thescrew member6 of the currently used golf club is removed, and the currently used or old shaft is removed from thehead1 together with the currently usedtop portion7 and screwmember6. Next, a new shaft (a shaft case/shaft connected assembly), which includes a shaft case, a top portion and a screw member mounted thereon, is inserted into thehead1 and is then fixed to thehead1 using thescrew member6 andtop portion7.

In this manner, according to the present embodiment, the operation to mount and replace a shaft can be carried out very simply and quickly. Here, conventionally, to replace a shaft, the hosel portion of a currently used golf club is heated to destroy the structure of a hardened adhesive, and the currently used or old shaft is removed; and, after then, a new shaft is fixed using an adhesive. That is, it takes several hours to about one day to complete this replacing operation. On the other hand, according to the present embodiment, by previously having mounted ashaft case5 on a new shaft using an adhesive, such shaft replacing operation can be finished several minutes or so. This can realize a using system in which shafts each with a shaft case connected thereto for various specifications have been previously prepared and different shafts are sequentially mounted on the same head main body for testing the hitting feelings of the respective shafts.

Here, according to the present embodiment, owing to provision of the

inclined surfaces

3dand5c, the inner surface of the hole deep side of thehosel3 and the outer surface of the lower end side of theshaft case5 are respectively formed in a non-circular section shape (that is, the section thereof perpendicular to the axial line thereof is non-circular), and these

inclined surfaces

3dand5care engaged with each other.

This can reduce the generation of rickety motion in theshaft4 and can prevent theshaft4 from rotating around the axial direction thereof. That is, the fixture rigidity of theshaft4 in the torque direction thereof is enhanced.

Also, there are provided the pair of

inclined surfaces

5cand5c, and the leading end side of theshaft case5 is thereby formed in a tapered shape. This can facilitate the insertion of theshaft case5 into thehosel3.

According to the invention, like ashaft case5A shown inFIGS. 9A and 9B, there may also be provided a pair ofparallel surfaces5fon the leading end side of the shaft case. By gripping theparallel surfaces5fusing a gripping tool, theshaft case5A can be easily mounted onto and removed from theshaft4. The remaining structures of theshaft case5A shown inFIGS. 9A and 9B are the same as the above-mentionedshaft case5 and thus the same designations show the same composing portions respectively.

The hosel, shaft case and screw member may preferably be made of metal and, more preferably, they may be made of aluminum or titanium, or an aluminum alloy or a titanium alloy. Thetop portion7 may preferably be made of aluminum or synthetic resin. Thehosel3, which is formed separately from thehead1, may preferably be made of material having an equal or lower specific gravity than the head main body; for example, as this material, there may be used a titanium alloy, aluminum, an aluminum alloy, a magnesium alloy, FRP, or synthetic resin.

The material of the head is not limited to a specific one but, in the case of a wood type golf club head, it may be made of, for example, a titanium alloy, an aluminum alloy, or stainless steel.

According to the present embodiment, although there are provided a pair of

inclined surfaces

5c,5cand a pair of

inclined surfaces

3d,3d, the number of inclined surfaces may also be one, or three or more. However, as shown in the drawings, it may preferably be a pair.

Here, as a grip to be mounted on theshaft4, there can be used a grip the section of which is non-circular. For example, there is available a grip structured such that the lower side surface of the outer peripheral surface thereof, which faces the ground when a golfer addresses a ball, is expanded out from the remaining surfaces thereof. In this case, to mount theshaft case5 onto theshaft4, when the direction of the peripheral direction of theshaft case5 is previously set so as to correspond to the grip expansion portion, the shaft can be mounted onto the head in such a manner that the grip expansion portion faces the ground positively.

FIGS. 11 to 15 respectively show an example of such grip having a non-circular section, andFIG. 10 shows a golf club with such grip mounted on theclub head1.

Here,FIG. 11 is a side view of agrip9,FIG. 12 is a vertical section view of thegrip9 in the longitudinal direction thereof,FIG. 13 is a section view taken along the XIII-XIII line shown inFIG. 12,FIG. 14 is an enlarged view ofFIG. 13, andFIG. 15 is an enlarged section view taken along the XV-XV line shown inFIG. 10, respectively.

As shown inFIG. 10, the leading end of theshaft4 is inserted into the hosel of thehead1 and is fixed thereto using an adhesive. Here, preferably, the upper end side of thescrew member6 may have a conical shape like a ferrule as shown inFIG. 10, because this shape can be eliminate a strange feeling from the appearance of thescrew member6.

Thegrip9 has a substantially cylindrical shape which includes aninsertion hole9bfor insertion of theshaft4, while thegrip9 is made of rubber or the like. A portion (inFIGS. 12,13,14 and15, the lower side) of thegrip9 existing in the peripheral direction thereof is formed as athick portion9a. Thisthick portion9aextends in the longitudinal direction of thegrip9. Thethick portion9ais formed such that the section shape of the inner peripheral surface of the grip9 (that is, the section shape thereof in a direction perpendicular to the longitudinal direction of the grip9) can provide a string-like shape. When theshaft4 is inserted into thisgrip9, as shown inFIG. 15, thethick portion9ais pushed outwardly from inside and the outer periphery thereof is expanded to thereby form a projectingportion9c. This projectingportion9cextends in the longitudinal direction of the grip9 (in the longitudinal direction of the shaft4). The

shaft cases

5,5A may have been previously mounted on theshafts4 in such a manner that the projectingportion9cfaces downward, that is, faces the ground when a golfer holds the golf club for addressing a ball, whereby there have been previously structured shaft case/shaft connected assemblies. In this case, even when any one of the shaft case/shaft connected assemblies is mounted on thehead1, the projectingportion9cis always disposed correctly on the ground side in the golfer's address position.

Although there is used a golf club head of a wood type in the above-mentioned embodiment, the invention can also be applied to golf club heads of other types such as a utility type, an iron type and a patter.

Here, in the case of the golf club head of the illustrated hollow type, since thehosel3,hosel installation portion2g,shaft case5 and screwmember6 are provided, the weight of the heel side of the head is large when compared with an ordinary gold club head. In view of this, preferably, the thickness of the toe side or back portion of the head may be increased or a weight may be provided on the toe side of the head to thereby keep its weight balance.

FIGS. 16 and 17 respectively show an example of such golf club head. Specifically,FIG. 16 is a front view of agolf club head1A including athick portion2tformed on thetoe portion2dside of a headmain body2 thereof, andFIG. 17 is a side view of agolf club head1B having aweight screw2wmounted on theback portion2fof a headmain body2 thereof. Here, in the sole portion, toe-side side portion or back portion of the golf club head, there may be formed a female screw hole for weight adjustment, and also there may be prepared a plurality of screws which are different in weight from each other. In this case, by replacing one screw with another differing in weight, the position of the center of gravity of the golf club head can be adjusted.

Specifically, as shown inFIG. 16, the toe side of the head may be formed thick or a weight member having a larger specific gravity than the head main body may be disposed on the toe side of the head. Structurally, when compared with an ordinary golf club head, the heel side of the present golf club head tends to be heavy.

The remaining structures of the golf club heads shown inFIGS. 16 and 17 are similar to the golf club head shown inFIGS. 1 and 2, and the same designations respectively show the same composing elements.

According to the invention, like a head1C shown inFIG. 18, a headmain body2C and ahosel3C may also be formed as an integral body. The remaining structures of the head shown inFIG. 18 are similar to the head shown inFIG. 3, and the same designations respectively show the same composing elements.

According to the invention, like ahead1D shown in FIGS.19 and20, instead of the taperedtop portion7, a nut-shapedtop portion7A may also be threadedly engaged with themale screw5nof theshaft case5, and aferrule19 may be mounted on top of thetop portion7A. The remaining structures of the head shown inFIGS. 19 and 20 are similar to the head shown inFIG. 18, and the same designations respectively show the same composing elements.

According to the invention, there may also be employed a structure in which, instead of the nut-shapedtop portion7A, an enlarged-diameter portion is formed in the upper end of the shaft case.FIG. 21 is a section view of the heel side of agolf club head1E having the above structure,FIG. 22 is a perspective view of ahosel3E, ashaft case5E and ascrew member6E used in thegolf club head1E, andFIG. 23 is a section view of thehosel3E,shaft case5E, and screwmember6E.

In the upper end of theshaft case5E, there is formed integrally therewith an enlarged-diameter portion51 having a tapered outer peripheral surface the diameter of which decreases as it goes upward. The lower surface of the enlarged-diameter portion51, that is, the upper step surface thereof is superimposed on the upper surface of thescrew member6E through aspacer7f. In the outer peripheral surface of theupper half section6aof thescrew member6E, there is formed aflat end face6eon which a tool such as a wrench or a monkey wrench can be put.

The lower portion of the enlarged-diameter portion51 of theshaft case5E is formed as asmall diameter portion52. Thescrew member6E is rotatably fitted with the outer surface of thesmall diameter portion52. The lower portion of theshaft case5E than thesmall diameter portion52 is formed as alarge diameter portion54 having a larger diameter than thesmall diameter portion52. The lower end face of thescrew member6E is contacted through aspacer6gwith a step surface (lower step surface)53 interposed between thesmall diameter portion52 andlarge diameter portion54. Similarly to the above-mentionedscrew member6, amale screw6bis formed on the outer peripheral surface of the lower half section of thescrew member6E.

In the inner peripheral surface of the upper end side of thehosel3E, there is cut formed afemale screw3a. In the present embodiment, the deeper portion of thehosel3E than thefemale screw3ais formed ascylindrical portion3c. Thiscylindrical portion3chas an inside diameter which allows thelarge diameter portion54 to be fitted into thecylindrical portion3c.

The remaining structures of the head according to the present embodiment are similar to the head shown inFIGS. 1 to 8, and the same designations respectively show the same composing elements.

To assemble this golf club, as shown inFIGS. 22 and 23, the leading end of theshaft4 may have been inserted into theshaft case5E and fixed thereto using an adhesive previously. Preferably, the adhesive may be applied onto the outer peripheral surface of the leading end portion of theshaft4, and theshaft4 may be then inserted down to the deeper-most portion of thehole5aof theshaft case5E.

Theshaft case5E of a shaft case/shaft connected assembly, which includes thescrew member6E and also to which theshaft case5E is fixed in this manner, as shown inFIGS. 22 and 23, is inserted into thehosel3E of thehead1, and the

inclined surfaces

5c,5cand

inclined surfaces

3d,3dare superimposed on top of each other. Next, themale screw6bof thescrew member6E is screwed into thefemale screw3aof thehosel3E.

Accordingly, as shown inFIG. 21, the lower end face of thescrew member6E is pressed against thestep surface53 of theshaft case5E, and theinclined surfaces5cof theshaft case5E are respectively pressed against their associatedinclined surfaces3dof thehosel3 through theelastic members8, whereby theshaft case5E is fixed to thehosel3E. Since theshaft case5E andshaft4 are firmly adhered to each other using the adhesive, there can be completed a golf club in which theshaft4 andhead1E are unified as an integral body.

To pull out theshaft case5E from this golf club, thescrew member6E may be turned in the loosening direction thereof. Since themale screw6bof thescrew member6 is in threaded engagement with thefemale screw3aof thehosel3E, when thescrew member6E is turned in the loosening direction thereof, thescrew member6E is moved (threadedly moved) upwardly to push up the enlarged-diameter portion51, whereby theshaft case5E is moved upwardly. As a result of this, theshaft case5E is moved in the upward direction where it moves apart from thehosel3E, and thus theshaft case5E can be removed easily.

In the present golf club, the enlarged-diameter portion51 is formed to have a tapered shape. However, alternatively, like theshaft case5F of agolf club1F shown inFIGS. 24 to 26, there may also be formed an enlarged-diameter portion55 having a flat flange shape, and aferrule19 may be mounted on top of the enlarged-diameter portion55. The remaining structures of the golf club head shown inFIG. 24 or26 are similar to the golf club head shown inFIGS. 21 to 23 and the same designations respectively show the same composing elements.

According to the above embodiments, each of the shafts for the shaft replacing operation may have a different stiffness distribution. For example, shafts, each of which has EI values shown inFIG. 27, can be used for the shaft replacing operation. Besides,FIG. 27 exemplary shows relation between EI values and measurement sites of two shafts A and B, and the EI values are indications of flexural stiffness.

Further, each of the shafts may have a different torque, a different weight or a different stiffness: for example, R or S. These shafts can be used for the shaft replacing operation. Of course, even if the shafts are different in a plurality of properties mentioned in the above, the shafts aloes can be used for the shaft replacing operation.

According to the above, a user can replace the shafts to adjust the golf club to a trim of the user. Further, according to the above, in a case that a plurality of users gather, each of the users can choose one's own shaft.

Further, in the present invention, a plurality of shaft cases, each of which has a hole having a different internal diameter, and a plurality of shafts, each of which has a different tip diameter, may be provided so that the user can try a golf club configured by combining one of the shaft cases and one of the shafts.

Further, in the present invention, a plurality of golf club heads may be provided for replacement parts corresponding to one shaft. Each of the golf club heads may have a different loft angle, a different lie angle, a different volume or a different barycentric position.

Claims

1. A method for replacing a shaft of a golf club, the golf club including: a head having a hosel; the shaft; a shaft case fixed to one end of the shaft, and configured to be inserted into the hosel, the shaft case being formed in a substantially cylindrical shape; and a ring-shaped screw member configured to be screwed into one end of the hosel to fix the shaft case in the hosel, and to be fitted with an outer face of an one end of the shaft case, the ring-shaped screw member being noncontact with the shaft, the method comprising:

fixing a newly-provided shaft to a newly-provided shaft case corresponding to the hosel;

unscrewing the ring-shaped screw member from the hosel;

removing the shaft case with the shaft from the hosel;

inserting the newly-provided shaft case with the newly-provided shaft to the hosel; and

screwing the ring shaped screw member on the hosel.

2. A method for replacing a head, which has a hosel, of a golf club, the golf club including: the head; a shaft; a shaft case fixed to one end of the shaft, and configured to be inserted into the hosel, the shaft case being formed in a substantially cylindrical shape; and a ring-shaped screw member configured to be screwed into one end of the hosel to fix the shaft case in the hosel, and to be fitted with an outer face of an one end of the shaft case, the ring-shaped screw member being noncontact with the shaft, the method comprising:

unscrewing the ring-shaped screw member from the hosel;

removing the shaft case with the shaft from the hosel;

providing a newly-provided head having a newly-provided hosel;

inserting the shaft case with the shaft to the newly-provided hosel; and

screwing the ring shaped screw member on the newly-provided hosel.