JP4709111B2 - Golf club - Google Patents

Description

  The present invention relates to a golf club, and more particularly to a golf club head in which a hosel hole of a head that fixes one end of a shaft opens to the outside at a lower position closer to a sole portion than a top portion of the head.

  Conventionally, the axis of the shaft is arranged so as to intersect the central axis of the hosel hole formed in the head, and the axis of the shaft is rotated relative to the central axis of the hosel hole. Golf clubs with adjustable face angles have been developed.

  Such a golf club has a crank-shaped metal joint member that connects the club head main body and the club shaft, and the front end of the joint member is inserted into a joint hole formed in the club head main body and formed at the rear end. There is a configuration in which the center axis of the joint hole and the axis of the club shaft are bent in parallel or at a predetermined angle so as not to be positioned on the same line by inserting the tip of the club shaft into the shaft insertion hole. (For example, refer to Patent Document 1).

  A golf club in which a cylindrical neck socket is mounted in a socket mounting hole formed in the neck portion of the head and the shaft is mounted in the shaft mounting hole of the neck socket. A shaft insertion hole is linearly extended from the center of the tip of the projecting extension part to the position eccentric from the center of the insertion part to be installed in the socket installation hole, and this neck socket is rotated in the socket installation hole. By doing so, there is one that adjusts the lie angle and the face surface angle (see, for example, Patent Document 2).

Furthermore, a golf club that covers the neck with a hosel is attached to the neck hole protruding from the head and the shaft assembly including the shaft and bush is attached to this bush. And a cylindrical outer surface that forms an inclined axis, and the position of the head relative to the axis of the shaft is adjusted by the rotational position of the lower end portion of the shaft assembly (see, for example, Patent Document 3).
Japanese Utility Model Publication No. 5-74561 Japanese Utility Model Publication No. 3-24162 Japanese translation of PCT publication No. 1-501291

  However, in a golf club in which the head body and the club shaft are connected by a crank-shaped metal joint member, a shaft insertion hole for inserting the front end of the club shaft is formed at the rear end located outside the club head body. Therefore, a large load acts on the bent portion that connects the front end and the rear end in a crank shape. In order to maintain the strength against this large load, the metal joint member becomes large and the weight increases.

  Also, in a golf club in which a shaft is attached to the neck portion of the head via a neck socket, the shaft insertion hole of the neck socket is inclined starting from the center position of the tip of the extended portion, and is eccentric from the center position as it extends through the insertion portion. Since the amount increases, when the inclination angle of the shaft insertion hole is increased, the neck socket becomes larger and the weight also increases.

  Further, a golf club in which a bush is mounted in a neck hole protruding from the head is difficult to hold because the shaft and hosel are bent from the tip of the bush, that is, the tip of the neck protruding from the head.

  The present invention has been made based on such circumstances, and an object thereof is to provide a high-strength and lightweight golf club that can adjust the inclination of the shaft relative to the head over a wide range without causing a sense of incongruity. To do.

A golf club of the present invention that achieves the above object comprises a head that is fixed to one end of a shaft via a neck member at a specified lie angle and loft angle with respect to a reference horizontal plane on which a sole portion is placed. A golf club in which a hosel hole of a head that fixes one end of a shaft through a member opens to the outside at a position lower than the top portion of the head, and the outer peripheral surface of the neck member inserted into the hosel hole is a cylinder And a shaft fitting hole that opens at the outer end of the extension portion. The shaft fitting hole has a central axis line. Inclined with respect to the central axis of the outer peripheral surface of the insertion portion, and the intersection of the central axis of the shaft fitting hole and the central axis of the outer peripheral surface of the insertion portion is disposed at the boundary between the insertion portion and the extension portion It is, before from the point of intersection Axial length to the end portion of the shaft fitting hole terminates at the insertion portion is shorter than the axial length of the insertion portion to be inserted into the hosel bore, wherein the insertion portion is inserted into the hosel bore A hollow portion having a diameter larger than that of the shaft fitting hole is provided between the inserted end and the end portion of the shaft fitting hole .

  It is preferable that the outwardly extending portion has an outer shape that is coaxial with the outer peripheral surface of the shaft.

  In addition, there is a step portion disposed on the outer peripheral portion between the insertion portion and the outer extension portion, and the step portion contacts the outer surface of the head within a plane perpendicular to the central axis of the hosel hole. It may have a contact surface in contact therewith.

  Moreover, it is preferable that the said insertion part has a hollow part formed adjacent to the insertion end.

According to this golf club, the axial length from the intersection of the center axis of the shaft fitting hole and the center axis of the outer peripheral surface of the insertion portion to the terminal portion where the shaft fitting hole terminates in the insertion portion is By being shorter than the axial length of the insertion portion inserted into the head, the tilt of the shaft can be adjusted over a wide range efficiently only by slightly rotating the neck member relative to the head. The insertion part of the neck member has a hollow part larger in diameter than the shaft fitting hole between the insertion end inserted into the hosel hole and the terminal part of the shaft fitting hole, thereby joining the insertion part. The neck member can be reduced in weight while securing the area. In addition, the neck member is attached to the hosel hole of the head via the insertion portion, and the shaft is attached to the shaft fitting hole extending from the outer extension portion into the insertion portion, thereby securing the attachment strength between the head and the shaft via the neck member. The neck member can be a lightweight structure. Further, since no bent portion is formed outside the hosel hole, even when the inclination of the shaft with respect to the head is greatly changed, the bent portion is not formed outside, and the golf club can be held without a sense of incongruity.

  When the outer extending portion of the neck member has an outer shape that is coaxial with the outer peripheral surface of the shaft, the outer extending portion can be reduced in weight particularly as a thin-walled structure.

  Further, when the step formed on the outer peripheral portion between the insertion portion and the extension portion has a contact surface that contacts the outer surface of the head in a plane perpendicular to the central axis of the hosel hole, Even if the neck member is rotationally adjusted with respect to the head, a gap is not formed between the neck member and the head, and a smooth outer surface shape can be maintained regardless of the adjustment position.

  In addition, when the insertion portion has a hollow portion adjacent to the insertion end, a sufficient joint surface can be secured between the insertion portion and the head, and the weight can be reduced while improving the fixing strength.

FIG. 1 shows an entire golf club 10 according to a preferred embodiment of the present invention.
The golf club 10 of the present embodiment has, for example, a predetermined lie angle α with respect to a reference horizontal plane H and a face surface angle (loft angle) (not shown) at one end, that is, the tip of a shaft 12 formed into a tubular structure with fiber reinforced resin or metal. The hollow structure head 14 is set and fixed, and a grip 16 formed of a flexible material or a soft material such as natural rubber or synthetic rubber is attached to the base end, and is formed as a hollow structure wood type golf club. is there.

  Here, the lie angle α is an angle of an axis 12a that is a central axis of the shaft 12 with respect to a sole portion or a reference horizontal plane H described later, and when the golf club 10 is set with the sole portion 18 of the head 14 grounded, The angle of the central axis 12a of the shaft 12 with respect to a reference horizontal plane H passing through the sole portion 18 and the ground is defined. The face surface angle is an angle formed between the hitting surface of the face portion 20 and a vertical surface orthogonal to the reference horizontal plane H.

The head 14 of this embodiment is, for example, 150 to 470 cm ³ , preferably 200 to 470 cm ³ , has a head weight of 160 to 230 g, and has a predetermined face surface angle of, for example, 5 to 25 degrees. . The head 14 is formed with a predetermined lie angle α, which is an attachment angle with the axis 12a of the shaft 12, from 54 degrees to 62 degrees, for example.

  As shown in FIGS. 2 and 3, the head 14 of the golf club 10 includes a head main body 14a formed into a hollow integrated structure by casting or forging from a metal material such as stainless steel, titanium or titanium alloy. The head main body 14a has a sole portion 18 and a crown portion 22 extending from an upper edge portion and a lower edge portion of the face portion 20 for hitting a ball toward the back portion side, respectively. A side portion having a curved cross-sectional shape similar to a normal portion extends from the edge portion on the side of the toe portion 24 side of the face portion 20 to the edge portion on the heel portion 26 side of the face portion 20 through the back portion side. Has been. The face portion 20 and the crown portion 22 can be specified by a ridge line therebetween, but may be specified by a portion that is smaller than the radius of curvature of the surface portion that forms most of the face portion 20. The same applies to other parts that divide the face part 20.

  The head main body 14a is formed as a whole in an integrated structure, or is formed by forming each part as a separate member, for example, by providing a separate face member for the face part 20, and joining these members together. May be. When joining and forming such a some member, a fiber reinforced resin material can also be used for at least one part of the head main body 14a. In any case, the face member that forms the ball striking surface can be formed of a metal material such as stainless alloy, titanium, or titanium alloy, and other parts, that is, a material that is harder or stronger than the head body 14a. Is preferably used.

  In the head 14, the hosel portion 28 protrudes from the heel portion 26 side of the curved crown portion 22. The hosel portion 28 is formed at the top of a cylindrical portion 30 that protrudes from the crown portion 22 toward the sole portion 18 in a state slightly inclined in the direction of the toe portion 24. The shaft 12 can be fixed to the head 14 by inserting the tip end of the shaft 12 into the hosel hole 32 (FIG. 3) and bonding it. The top portion of the cylindrical portion 30 has a reference horizontal plane that is higher than a plane h that passes through the top portion 22a of the head 14, that is, the uppermost portion of the crown portion 22 that is the portion farthest from the reference horizontal plane H and is parallel to the reference horizontal plane H. An opening end 30a that opens to the outside at a low position where the height from H is low is formed.

  If the projecting amount of the cylindrical portion 30 from the crown portion 22, that is, the position in the height direction from the reference horizontal plane H of the opening end 30a where the hosel hole 32 opens to the outside, is lower than the top portion 22a of the head 14, The hosel portion 28 and the open end 32a protrude from the crown portion 22 when the end portion of the cylindrical portion 30 is disposed in the same plane as the curved outer surface of the crown portion 22. It will be in the state arrange | positioned in the head main body 14a without. The cylindrical portion 30 forming the hosel hole 32 is integrally formed of the same material as the head main body 14a. Of course, it is also possible to form the cylindrical portion 30 separately from the head main body 14a and using a different material. Although the end 30b of the cylindrical portion 30 on the sole 18 side is shown in a closed state, the cylindrical portion 30 and the head are formed by forming an opening in the whole or a part of the end 30b. The main body 14a can be reduced in weight.

  A neck member 34 is attached to the outer peripheral portion of the distal end portion of the shaft 12, and the shaft 12 is mounted in the hosel hole 32 from the opening end 30a of the tubular portion 30 via the neck member 34, and the head main body 14a. It is fixed to. A socket 36 attached to the shaft 12 is disposed at the outer end of the neck member 34. The socket 36 forms an outer shape that smoothly transitions without forming a large step between the neck member 34 and the shaft 12. Such a socket 36 is formed of, for example, a resin material with a length of about 3 to 20 mm along the axial direction of the shaft 12 and a tapered outer shape from the neck member 34 side toward the upper side of the shaft 12. Is preferred. The socket 36 may have a structure separate from or integrated with the shaft 12, and may be omitted.

  As shown in an enlarged view in FIGS. 4 to 6, the neck member 34 is formed in an overall cylindrical shape, and an insertion portion 38 to be inserted into the hosel hole 32, and a cylindrical portion in which the hosel hole 32 opens. 30 has an outwardly extending portion 40 projecting outward from the opening end 30a, and a shaft fitting hole 42 into which the distal end portion of the shaft 12 is fitted is located on the top side of the outwardly extending portion 40, that is, on the grip 16 (FIG. 1) side. The outer end 44 opens outward. The shaft fitting hole 42 passes from the opening of the outer end 44 to the insertion end 46 disposed in the hosel hole 32 through the outer extension 40 having an outer shape coaxial with the outer peripheral surface of the shaft 12. Extend and terminate before reaching the insertion end 46. Since the outer extending portion 40 has an outer shape that is coaxial with the shaft 12, the outer extending portion 40 can be formed into a thin-walled structure having a substantially uniform thickness along the entire circumference, and a light-weight structure can be obtained.

  In the present embodiment, a flange-like or partition-like wall portion 48 is formed at a portion where the shaft fitting hole 42 terminates, and can be brought into contact with the tip of the shaft 12. The insertion end 46 of the insertion portion 38 extends beyond the shaft fitting hole 42 and the wall portion 48, and a hollow portion 50 communicating with the shaft fitting hole 42 through the opening of the wall portion 48 is formed in the insertion end 46. It forms in the adjacent part. Thus, by extending the insertion portion 38 beyond the shaft fitting hole 42, it is sufficient to maintain the bonding strength between the inner peripheral surface of the hosel hole 32 and the outer peripheral surface of the insertion portion 38. While securing a joining surface and improving the fixing strength of the neck member 34 with respect to the head main body 14a, the weight of the neck member 34 can be reduced by the hollow structure.

  The axial length from the terminal end or wall 48 of the shaft fitting hole 42 to the insertion end 46 is such that the neck member 34 is inserted with respect to the joint area between the shaft 12 and the inner peripheral surface of the shaft fitting hole 42. It is preferable to set the joining area between the portion 38 and the inner peripheral surface of the hosel hole 32 to be substantially equal. By making the ratio of the joint area of the neck member 34 to the shaft and the head main body 14a substantially equal, the shape and weight of the neck member 34 can be optimized to a necessary and sufficient size.

In the present embodiment, the space 51 is formed between the insertion end 46 of the neck member 34 and the closed end 30b of the cylindrical portion 30, but the length of the cylindrical portion 30 extending in the head main body 14a. Can be made to correspond to the length of the insertion portion 38 and the space 51 can be omitted. An appropriate weight member is disposed in the hollow portion 50 formed in the head main body 14a or in the space portion 51 between the insertion end 46 of the insertion portion 38 and the end portion 30b of the cylindrical portion 30, and the head It is also possible to adjust the weight balance of 14.

  The insertion portion 38 has a cylindrical outer peripheral surface corresponding to the hosel hole 32. When the insertion portion 38 is mounted in the hosel hole 32, the central axis 38 a of the outer peripheral surface of the insertion portion 38 is the central axis 32 a of the hosel hole 32. And are arranged coaxially. On the other hand, the shaft fitting hole 42 has a center line 42a disposed coaxially with the axis 12a of the shaft 12 when fitted to the tip end portion of the shaft 12, and this center line 42a is the center axis 38a of the insertion portion 38. The intersection C of the central axes 38 a and 42 a is arranged at the boundary between the insertion portion 38 and the extension 40.

  Therefore, the thickness of the insertion portion 38 changes greatly along the circumferential direction at the end portion of the shaft fitting hole 42, that is, in the vicinity of the wall portion 48. A thick portion 39b is formed. The inclination angle of the central axis 38a of the outer peripheral portion of the insertion portion 38 with respect to the central axis 32a of the hosel hole 32 is increased as the end portions where the minimum thickness portion 39a and the maximum thickness portion 39b are formed are brought closer to the intersection C. Can be bigger. That is, when the outer diameter is the same, the inclination angle of the central axis 38a with respect to the central axis 32a of the hosel hole 32 can be increased as the length of the shaft fitting hole 42 in the insertion portion 38 is shorter. The weight can be reduced.

  In the present embodiment, an outer peripheral flange-shaped stepped portion 52 along the circumferential direction is integrally formed on the outer peripheral portion of the boundary portion where the intersection C is disposed. The stepped portion 52 has a tapered outer surface that is reduced in diameter toward the outer end 44 side of the neck member 34, and is disposed in a plane perpendicular to the outer peripheral surface of the insertion portion 38 on the insertion end 46 side. A contact surface 54 that contacts the open end 30 a of the cylindrical portion 30 is formed. By disposing the contact surface 54 in a plane perpendicular to the outer peripheral surface of the insertion portion 38, even if the insertion portion 38 rotates about the central axis 32 a of the hosel hole 32, A gap or the like is not formed between the opening end 30a and the contact can always be maintained. Moreover, the intersection C is arranged at the boundary between the insertion portion 38 of the neck member 34 and the extended portion 40, that is, at the opening end 30 a of the cylindrical portion 30, so that the extended portion 40 and the shaft 12 are linearly formed from the hosel 28. The state where the tip portion is bent and the bent end portion cannot be seen from the outside. Therefore, there is no sense of incongruity at the time of addressing.

  Such a golf club 10 can change the position of the axis 12a of the shaft 12 with respect to the head body 14a according to the golfer's preference. For example, as shown by a solid line in FIG. 4, from the state of the lie angle α1 in which the minimum thickness portion 39a of the insertion portion 38 is disposed on the crown portion 22 side, the neck member 34 and the shaft are centered on the central axis 32a of the hosel hole 32. When the shaft 12 is rotated, the extended portion 40 of the neck member 34 and the shaft 12 are swung so as to form a conical shape having the intersection C as a vertex, and as shown by a solid line in FIG. It can arrange | position in the position which is arrange | positioned at the 26th side and forms lie angle (alpha) 2. Although only the lie angle α is shown in the figure, it is obvious that the face surface angle, the relative position of the face surface, and the like can be adjusted. For example, the face surface angle (so-called loft angle) decreases when the minimum thickness portion 39a is disposed on the face portion 20 side, and conversely increases when disposed on the back portion side.

  When applied to an actual golf club 10, the neck member 34 is made of a metal such as aluminum, an aluminum alloy, a magnesium alloy, a titanium alloy, or pure titanium, a resin such as polycarbonate (PC) or ABS, or a fiber reinforced resin. It is possible to form. The golf club in which the neck member 34 is fixed to the head main body 14a using an adhesive is resistant to heat and recyclable in order to easily replace or adjust the shaft 12 by separating the adhesive portion by heating. It is preferable to use an excellent lightweight metal. In addition, when surface treatment is performed by a method other than painting, such as anodizing, plating, ion plating, etc., the appearance is not impaired during the heat treatment even if reshafting such as replacement or adjustment of the shaft is performed.

  Usually, the outer diameter of the shaft 12 of the golf club is 8.4 mm to 11 mm, and the thickness of the minimum thickness portion 39a in the insertion portion 38 is determined from the strength of the cylindrical portion 30 and the limit on molding of the neck member 34. When the thickness is 0.3 mm, the outer diameter of the insertion portion 38 is preferably formed in the range of 10.0 mm to 13.0 mm. Further, by forming the axial length of the shaft fitting hole 42 to 25 mm to 60 mm, it is possible to ensure a suitable adhesion or bonding area with the shaft 12. If the axial length of the shaft fitting hole 42 is too short than this range, the adhesive force is insufficient, and if it is too long, the weight increases. On the other hand, since the insertion portion 38 joined in the hosel hole 32 has a larger diameter than the outer diameter of the shaft 12, the axial length of the insertion portion 38 is shorter than the axial length of the shaft fitting hole 42. For example, it is preferably 20 to 40 mm, particularly about 23 to 30 mm.

Further, as the length of the shaft fitting hole 42 in the insertion portion 38, that is, the distance between the intersection C and the wall portion 48 which is the terminal portion of the shaft fitting hole 42 is shorter, the center of the hosel hole 32 as described above. Although it is possible to increase the inclination angle of the central axis 38a of the outer peripheral portion of the insertion portion 38 with respect to the axis 32a, it is preferable that the angle be about 12 mm to 30 mm in order to form a sufficient adhesion area. By forming the inner diameter of the hollow portion 50 formed between the terminal end portion of the shaft fitting hole 42 and the insertion end 46 of the insertion portion 38 to be larger than the inner diameter of the shaft fitting hole 42, the insertion portion The neck member 34 can be reduced in weight while securing an adhesion area between the tubular portion 30 and the tubular portion 30.

  On the other hand, the outer extending portion 40 can be formed to have an appropriate outer diameter as long as it conforms to the outer shape of the shaft 12, but is larger than the outer diameter of the insertion portion 38 and the outer diameter of the insertion portion 38. It is preferable that it is 1.4 times or less. If the outer diameter of the outer extension 40 is formed to be equal to or smaller than the outer diameter of the insertion section 38, stress may concentrate near the intersection C and breakage, which is 1.4 times the outer diameter of the insertion section 38. This is because the thickness of the extended portion 40 is increased and the weight is increased when it is formed larger than this.

  Such a neck member 34 can change the range in which the lie angle and the face surface angle are adjusted by changing the inclination angle of the central axis 38 a of the outer peripheral portion of the insertion portion 38 with respect to the central axis 32 a of the hosel hole 32. it can. For example, by preparing a plurality of neck members 34 having different inclination angles of the central axis 38a with respect to the central axis 32a, the neck member 34 can be adjusted in various ranges according to the golfer's preference.

  As a preferable example of the neck member 34, when the inner diameter of the shaft fitting hole 42 is set to 9.0 mm corresponding to the outer diameter of the shaft 12, the outer diameters of the insertion portion 38 and the outer extension portion 40 are 11.0 mm, 12 respectively. 0.0 mm, the inner diameter of the hollow portion 50 is 9.6 mm, the axial lengths of the insertion portion 38 and the extension portion 40 are 25 mm and 23 mm, and the axial length between the wall portion 48 and the contact surface 54 is 16 mm. The thickness of the minimum thickness portion 39a is 0.3, and the angle between the central axis 42a of the shaft fitting hole 42 and the central axis 38a of the outer peripheral portion of the insertion portion 38 is 2.51. An endurance test was conducted on a neck member made of an alloy (AA6061) using a robot that hits at a speed of 50 m / s, and no damage was observed even with 3000 shots.

  According to the above-described golf club 10, the intersection C between the center axis 42 a of the shaft fitting hole 42 and the center axis 38 a of the outer peripheral surface of the insertion portion 38 is disposed at the boundary portion between the insertion portion 38 and the extension portion 40. Thus, it is possible to adjust the inclination of the shaft 12 over a wide range efficiently by slightly rotating the neck member 34 with respect to the head 14. Further, the neck member 34 is attached to the hosel hole 32 of the head main body 14 a via the insertion portion 38, and the tip of the shaft 12 is attached to the shaft fitting hole 42 extending from the outer extension portion 40 into the insertion portion 38. The attachment strength between the head 14 and the shaft 12 via the member 34 is ensured, and the neck member 34 can be a lightweight structure. Further, since the bent portion is not formed outside the hosel hole 32, even when the inclination of the shaft 12 with respect to the head 14 is greatly changed, the bent portion is not formed outside the head 14, and the golf club 10 can be used without a sense of incongruity. Can be ready.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made. For example, instead of forming the neck member 34 separately from the shaft 12 as in the above-described embodiment, the neck member 34 may be formed integrally with the tip of the shaft 12. In this case, it is not necessary to consider the thickness of the minimum thin portion 39a of the insertion portion 38, and the weight can be further reduced.

1 is an overall view of a golf club according to a preferred embodiment of the present invention. The enlarged view of the head of the golf club of FIG. FIG. 3 is a partial cross-sectional view showing the inside of a hosel part of the head of FIG. 2. The elements on larger scale of FIG. Explanatory drawing shown in the state which decomposed | disassembled the hosel part. The enlarged view similar to FIG. 4 of the state which rotated the neck member.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Golf club, 12 ... Shaft, 14 ... Head, 14a ... Head main body, 18 ... Sole part, 22a ... Top part, 32 ... Hosel hole, 32a, 38a, 42a ... Center axis, 34 ... Neck member, 38 ... Insertion part , 40 ... extended portion, 42 ... shaft fitting hole, C ... intersection.

Claims (4)

A head that is fixed to one end of the shaft through a neck member at a specified lie angle and loft angle with respect to a reference horizontal plane on which the sole portion is placed, and the head that fixes one end of the shaft through the neck member A golf club in which a hosel hole opens outside at a position lower than the top of the head,
The neck member includes an insertion portion having a cylindrical outer peripheral surface to be inserted into the hosel hole, an extension portion that protrudes outward from the opening end of the hosel hole, and a shaft fitting that opens at the outer end of the extension portion. The shaft fitting hole has a central axis inclined with respect to the central axis of the outer peripheral surface of the insertion portion, and the center axial line of the shaft fitting hole and the central axis of the outer peripheral surface of the insertion portion are An intersection point is disposed at a boundary portion between the insertion portion and the extension portion, and an axial length from the intersection point to a terminal portion where the shaft fitting hole terminates in the insertion portion is inserted into the hosel hole. Shorter than the axial length of the insertion portion, and the insertion portion is larger in diameter than the shaft fitting hole between the insertion end inserted into the hosel hole and the terminal end portion of the shaft fitting hole. A golf club having a hollow portion .   The golf club according to claim 1, wherein the outer extending portion has an outer shape that is coaxial with an outer peripheral surface of the shaft.   There is a step portion disposed on the outer peripheral portion between the insertion portion and the outer extension portion, and the step portion is in contact with the outer surface of the head in a plane perpendicular to the central axis of the hosel hole. The golf club according to claim 1, wherein the golf club has a contact surface.   The golf club according to claim 1, wherein the insertion portion has a hollow portion formed adjacent to the insertion end.

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