JP2015054037A - Shaft and Golf Club - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shaft capable of reducing EI of the shaft while securing strength of the shaft, and a golf club comprising the shaft.SOLUTION: A shaft 1 includes an outer shell. The outer shell comprises a cylindrical part 2, and a curved part 3 that is provided in such a manner as to continue into the cylindrical part 2 and that has a plurality of protrusions 3a arranged side by side in an outer peripheral direction of the shaft 1. The curved part 3 has a uniform thickness. The plurality of protrusions 3a are elongated in the elongation direction of the shaft 1.

Description

  The present invention relates to a shaft and a golf club.

  Normally, the bending rigidity (EI) of a shaft of a golf club is increased in order to ensure strength. Thus, when the EI of the shaft increases, it becomes difficult to flex the shaft. Some golfers have a preference for where the shaft is to be flexed, for example, some prefer to have the shaft at one of the desired flexure positions of the golfer. Such golfers are required to reduce the hand EI of the shaft.

  In order to reduce the EI of the shaft, it is conceivable to reduce the second moment of inertia (I) of the shaft. In order to reduce the second moment of inertia (I) of the shaft, it is conceivable to reduce the diameter of the shaft and reduce the thickness of the shaft. However, since many golfers feel uncomfortable when the shaft is gripped, for example, when the diameter of the hand side of the shaft changes, it is difficult to reduce the diameter of the shaft. Further, if the thickness of the shaft is reduced, the strength of the shaft is reduced, so that it is difficult to reduce the thickness of the shaft.

  Incidentally, a structure for increasing the strength of the shaft is disclosed in, for example, Japanese Patent Application Laid-Open No. 2011-30564 (Patent Document 1). In the structure described in Japanese Patent Application Laid-Open No. 2011-30564, a protrusion for reinforcement is formed on the inner diameter portion of the shaft. Further, a structure in which a protrusion is formed on the inner diameter portion of the shaft as in Japanese Patent Application Laid-Open No. 2011-30564 is disclosed in, for example, Japanese Utility Model Laid-Open No. 1-84673 (Patent Document 2). A structure in which a protrusion is formed on the outer diameter portion of the shaft is disclosed in, for example, Japanese Patent No. 3510143 (Patent Document 3).

JP 2011-30564 A Japanese Utility Model Publication No. 1-84673 Japanese Patent No. 3510143

  In the structure described in each of the above publications, the sectional moment of the shaft (I) increases because the sectional area of the shaft increases due to the protrusion formed on the inner diameter portion or the outer diameter portion of the shaft. Therefore, the EI of the shaft cannot be reduced.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a shaft capable of reducing the EI of the shaft while ensuring the strength of the shaft, and a golf club including the shaft.

  The shaft of the present invention has an outer shell. The outer shell includes a cylindrical portion and a curved portion that is provided continuously with the cylindrical portion and has a plurality of convex portions arranged side by side in the outer circumferential direction of the shaft. The curved portion has a uniform thickness, and a plurality of convex portions extend in the extending direction of the shaft.

  According to the shaft of the present invention, the curved portion has a plurality of convex portions arranged side by side in the outer peripheral direction of the shaft. The plurality of convex portions extend in the extending direction of the shaft. The plurality of convex portions function as so-called ribs. Since the convex portion can withstand a large pressure, the strength of the shaft can be secured by the plurality of convex portions. The curved portion has a uniform thickness. For this reason, since the increase in the cross-sectional area of a bending part can be suppressed, the increase in the cross-sectional secondary moment of a bending part can be suppressed. Thereby, the EI of the shaft can be reduced while ensuring the strength of the shaft.

  In the above-described shaft, the bending portion is provided in a range of a position separated from the tip of the shaft by 600 mm or more. In general, the hand position in the vicinity of the grip, which is a position separated by 600 mm or more from the tip of the shaft, is reduced in strength due to a reduction in the thickness of the shaft. In the shaft, by providing the curved portion at a position separated by 600 mm or more from the tip of the shaft, the EI of the shaft can be reduced while securing the strength at the hand position where the strength generally decreases.

  In the shaft described above, the curved portion includes a base that is adjacent to the plurality of convex portions in the outer circumferential direction and from which the plurality of convex portions protrude. Each of the plurality of convex portions and the base portion has an arc shape in a cross section in a direction perpendicular to the extending direction of the shaft. The curvature radius of the outer peripheral surface of each of the plurality of convex portions is smaller than the curvature radius of the outer peripheral surface of the base portion. For this reason, a convex part can endure a bigger pressure than a base. Therefore, the strength of the shaft can be ensured by the plurality of convex portions.

  In the shaft described above, the center of the arc-shaped circle on the outer peripheral surface of each of the plurality of convex portions is disposed equiangularly with respect to the center in the radial direction of the shaft over the entire circumference of the shaft. Thereby, the intensity | strength of a shaft is securable over the perimeter of a shaft with a some convex part.

  In the above shaft, the ratio of the maximum distance from the center in the radial direction of the shaft to the outer peripheral surface of each of the plurality of convex portions and the maximum distance to the outer peripheral surface of the base is 1.013 or more and 1.077 or less. Thereby, the intensity | strength of a shaft is securable with a some convex part.

  In said shaft, the curvature radius of each outer peripheral surface of a some convex part is 2.0 mm or more and 2.4 mm or less. The center of the arc-shaped circle on the outer peripheral surface of each of the plurality of convex portions is located in an area of 4.80 mm or more and 5.65 mm or less from the radial center of the shaft toward each outer peripheral surface of the plurality of convex portions. ing. Thereby, the intensity | strength of a shaft is securable with a some convex part.

  A golf club of the present invention includes the above-described shaft, a grip attached to one end of the shaft, and a golf club head attached to the other end of the shaft. Thereby, it is possible to obtain a golf club capable of reducing the EI of the shaft while ensuring the strength of the shaft.

  As described above, according to the present invention, it is possible to obtain a shaft capable of reducing the EI of the shaft while ensuring the strength of the shaft, and a golf club provided with the shaft.

It is a schematic plan view which shows the shaft of one embodiment of this invention. It is an enlarged view which shows the P section of FIG. It is sectional drawing which follows the III-III line of FIG. It is sectional drawing which follows the IV-IV line of FIG. FIG. 5 is an enlarged view of FIG. 4. It is a schematic plan view which shows the modification 1 of the shaft of one embodiment of this invention. It is a schematic plan view which shows the modification 2 of the shaft of one embodiment of this invention. 1 is a schematic perspective view showing a golf club according to an embodiment of the present invention. It is sectional drawing of the shaft of Example 1, Comprising: It is a figure corresponding to FIG. FIG. 6 is a cross-sectional view of Example 2, corresponding to FIG. 5. FIG. 6 is a cross-sectional view of Example 3, corresponding to FIG. 5. FIG. 6 is a cross-sectional view of Example 4 corresponding to FIG. 5. FIG. 10 is a cross-sectional view of Example 5, corresponding to FIG. 5. FIG. 10 is a cross-sectional view of Example 6 corresponding to FIG. 5. It is sectional drawing of Example 7, Comprising: It is a figure corresponding to FIG. 6 is a sectional view of Comparative Example 1. FIG. 10 is a cross-sectional view of Comparative Example 2. FIG. It is a figure which shows the measuring method of VM stress of an Example. It is a figure which shows the relationship between VM stress and the number of convex parts. It is a figure which shows the relationship between EI and the distance from the front-end | tip of a shaft. It is a figure which shows the relationship between thickness and the distance from the front-end | tip of a shaft.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
Initially, the structure of the shaft of this Embodiment is demonstrated.

  Referring to FIGS. 1 and 2, the shaft 1 has a taper shape whose diameter decreases from the root toward the tip along the longitudinal direction as a whole. The shaft 1 is made of steel, for example. The shaft 1 preferably has a mass of, for example, 100 g or less, and particularly preferably has a mass of 85 g or more, which is the mass of an ultralight steel shaft, and 98 g or less, which is the mass of a general lightweight steel shaft. preferable. Furthermore, even if it is a lightweight steel shaft, if the mass of the strength is 95 g or more and 98 g or less, it is still more preferable. The shaft 1 has an outer shell, and the outer shell has a cylindrical portion 2 and a curved portion 3.

  Referring to FIGS. 1 and 3, the cylindrical portion 2 has a cylindrical shape. As shown in FIG. 1, the cylindrical portion 2 has a plurality of cylindrical cylindrical members. Each of the plurality of cylindrical members is formed so as to extend along the extending direction (longitudinal direction) of the shaft 1. Each of the plurality of cylindrical members has a different diameter. A cylindrical member having a small diameter is inserted on the inner peripheral side of a cylindrical member having a large diameter among adjacent cylindrical members. Then, a part of the outer peripheral surface of the small-diameter cylindrical member on the side of the large-diameter cylindrical member is fitted to a part of the cylindrical member on the small-diameter side of the inner peripheral surface of the large-diameter cylindrical member. As shown in FIG. 3, the cylindrical portion 2 has a substantially circular cross-sectional shape.

  As shown in FIGS. 1 and 2, the bending portion 3 is provided continuously with the cylindrical portion 2. Referring to FIGS. 2 and 4, the bending portion 3 has a plurality of convex portions 3a and a base portion 3b. Moreover, the bending part 3 has uniform thickness. Here, the uniform thickness means substantially the same thickness because the thickness of the curved portion 3 includes a dimensional error during manufacturing. For example, if the difference in thickness of the curved portion 3 in the extending direction of the shaft 1 is ± 0.01 mm, it can be said that the thickness is uniform. In the present embodiment, the bending portion 3 is formed in the range of 600 mm or more and 800 mm or less from the tip of the shaft 1. The curved portion 3 is formed by swaging.

  As shown in FIG. 4, the plurality of convex portions 3 a are arranged side by side in the outer peripheral direction of the shaft 1. A plurality of convex portions 3 a extend in the extending direction of the shaft 1. In the present embodiment, for example, twelve convex portions 3a are formed. The base portion 3 b is adjacent to the plurality of convex portions 3 a in the outer peripheral direction of the shaft 1. A plurality of convex portions 3a protrude from the base portion 3b. 2-4, the some convex part 3a is formed so that it may protrude outside from the outer peripheral surface of the cylindrical part 2. As shown in FIG.

  Referring to FIG. 5, each of the plurality of convex portions 3 a and base portion 3 b has an arc shape in a cross section in a direction perpendicular to the extending direction of shaft 1. The arc shape of the plurality of convex portions 3a and the arc shape of the base portion 3b are smoothly continuous. The curvature radius 3ar of the outer peripheral surface of each of the plurality of convex portions 3a is smaller than the curvature radius 3br of the outer peripheral surface of the base portion 3b. In the present embodiment, the curvature radius 3ar of each outer peripheral surface of the plurality of convex portions 3a is, for example, not less than 2.0 mm and not more than 2.4 mm. The radius of curvature 3br of the outer peripheral surface of the base 3b is, for example, not less than 6.50 mm and not more than 7.75 mm.

  The distance Cp from the center C1 in the radial direction of the shaft 1 to the center C2 of the circular arc of the outer peripheral surface of each of the plurality of convex portions 3a is 4.80 mm to 5.65 mm. That is, the center C2 of the circular arc of the outer peripheral surface of each of the plurality of convex portions 3a is 4.80 mm or more from the radial center C1 of the shaft 1 toward the outer peripheral surface of each of the plurality of convex portions 3a. It is located in an area of 65 mm or less.

  Further, the center C2 of the arc-shaped circle on the outer peripheral surface of each of the plurality of convex portions 3a is disposed equiangularly with respect to the radial center C1 of the shaft 1 over the entire circumference of the shaft 1. That is, the angle formed by the line connecting the center C1 and one center C2 and the line connecting the center C1 and another center C2 adjacent to the one center C2 is the same over the entire circumference of the shaft 1. Here, “equal angle” means substantially the same angle because it includes a dimensional error in manufacturing the plurality of convex portions 3a. If the angle difference is ± 2 °, it can be said to be equiangular.

  Further, the maximum distance Da from the center C1 in the radial direction of the shaft 1 to the outer peripheral surface of each of the plurality of convex portions 3a is 6.80 mm or more and 8.05 mm or less, and from the center C1 in the radial direction of the shaft 1 to the base 3b. The maximum distance Db to the outer peripheral surface is not less than 6.5 mm and not more than 7.75 mm. Therefore, the ratio of the maximum distance Da from the center C1 in the radial direction of the shaft 1 to the outer peripheral surface of each of the plurality of convex portions 3a and the maximum distance Db to the outer peripheral surface of the base portion 3b is Da / Db is 1.013 or more. 0.077 or less. The distances Da, Db (curvature radius 3br) and the curvature radius 3ar are set after a plurality of convex portions 3a are set so that the base portion 3b is exposed between the adjacent convex portions 3a. . Specifically, when the distance Db is 6.5 mm, the curvature radius 3ar is set to 2.0 mm, the distance Da is set to 6.80 mm, and the distance between the center C1 and the center C2 is set to 4.80 mm. . When the distance Db is 7.75, the curvature radius 3ar is set to 2.4 mm, the distance Da is set to 8.05 mm, and the distance between the center C1 and the center C2 is set to 5.65 mm. Further, the minimum value 1.013 of Da / Db is obtained from Da = 7.85 and Db = 7.75, and the maximum value of Da / Db 1.077 is Da = 7.00 and Db = 6. .50.

  In the above embodiment, as illustrated in FIG. 1, the case where the bending portion 3 is formed at a position in the range of 600 mm or more and 800 mm or less from the tip of the shaft 1 has been described, but the position of the bending portion 3 is limited to this. Not. With reference to FIG. 6, in Modification 1 of the present embodiment, bending portion 3 is formed continuously from the front end of shaft 1, for example, from 600 mm to the rear end. Also in this modified example 1, the EI at hand of the shaft 1 which is one of the bending positions desired by the golfer can be reduced while ensuring the strength of the shaft 1. Although not shown, the bending portion 3 may be provided in the vicinity of the central portion in the longitudinal direction of the shaft 1, which is one of the bending positions desired by the golfer, or provided in the vicinity of the tip end side of the shaft 1. May be. Furthermore, the extending length of the bending portion 3 may be longer or shorter than that in the above embodiment.

  Moreover, although the said embodiment demonstrated the case where the some convex part 3a of the bending part 3 protrudes outward rather than the outer peripheral surface of the cylindrical part 2, as shown in FIGS. The shape of the plurality of convex portions 3a is not limited to this. With reference to FIG. 7, in the second modification of the present embodiment, the plurality of convex portions 3 a of the bending portion 3 do not protrude outward in the radial direction from the outer peripheral surface of the cylindrical portion 2. Each of the plurality of convex portions 3 a may be formed such that the outer peripheral surface of each of the plurality of convex portions 3 a has the same diameter as the outer peripheral surface of the cylindrical portion 2. In this case, the base portion 3 b has a diameter that the outer peripheral surface of the base portion 3 b is smaller than the outer peripheral surface of the cylindrical portion 2.

  Next, the configuration of the golf club of the present embodiment will be described. Hereinafter, an iron golf club will be described as an example of the golf club of the present embodiment.

  Referring to FIG. 8, golf club 10 of the present embodiment is configured by combining grip 11 and golf club head 12 with shaft 1 of the present embodiment. The golf club 10 includes a shaft 1, a grip 11 attached to one end of the shaft 1, and a golf club head 12 attached to the other end opposite to one end of the shaft 1. As the grip 11 and the golf club head 12, well-known ones can be adopted.

Next, the effect of this Embodiment is demonstrated.
According to the shaft 1 of the present embodiment, the bending portion 3 has a plurality of convex portions 3 a arranged side by side in the outer peripheral direction of the shaft 1. The plurality of convex portions 3 a extend in the extending direction of the shaft 1. The plurality of convex portions 3a function as so-called ribs. That is, since the convex part 3a can endure a big pressure, the intensity | strength of the shaft 1 is securable by the some convex part 3a. The curved portion 3 has a uniform thickness. For this reason, since the increase in the cross-sectional area of the bending part 3 can be suppressed, the increase in the cross-sectional secondary moment of the bending part 3 can be suppressed. Thereby, EI at hand of the shaft 1 which is one of the bending positions desired by the golfer can be reduced while securing the strength of the shaft 1.

  In addition, by providing the curved portion 3 in a range of a position that is separated by 600 mm or more from the tip of the shaft, it is possible to reduce the EI of the shaft 1 while ensuring the strength of the hand position where the strength generally decreases. it can.

  Further, since the curved portion 3 has a uniform thickness, the weight of the shaft 1 can be reduced as compared with, for example, a case where a protrusion is simply added to the inner diameter portion or the outer diameter portion of the shaft 1.

  Moreover, in the shaft 1 of this Embodiment, the curvature radius of each outer peripheral surface of the some convex part 3a is smaller than the curvature radius of the outer peripheral surface of the base 3b. For this reason, the convex part 3a can endure a larger pressure than the base part 3b. Therefore, the strength of the shaft 1 can be ensured by the plurality of convex portions 3a.

  Further, in the shaft 1 of the present embodiment, the center C2 of the circular arc of the outer peripheral surface of each of the plurality of convex portions 3a is relative to the center C1 in the radial direction of the shaft 1 over the entire circumference of the shaft 1. They are arranged at equal angles. Thereby, the intensity | strength of the shaft 1 is securable over the perimeter of the shaft 1 by the some convex part 3a.

  In the shaft 1 of the present embodiment, the ratio Da / Db between the maximum distance from the radial center C1 of the shaft 1 to the outer peripheral surface of each of the plurality of convex portions 3a and the maximum distance to the outer peripheral surface of the base portion 3b. Is 1.013 or more and 1.077 or less. Thereby, the intensity | strength of the shaft 1 is securable by the some convex part 3a.

  Moreover, in the shaft 1 of this Embodiment, the curvature radius of each outer peripheral surface of the some convex part 3a is 2.0 mm or more and 2.4 mm or less. The center C2 of the circular arc of the outer peripheral surface of each of the plurality of convex portions 3a is 4.80 mm or more and 5.65 mm or less from the radial center C1 of the shaft 1 toward each outer peripheral surface of the plurality of convex portions 3a. Located in the area. Thereby, the intensity | strength of the shaft 1 is securable by the some convex part 3a.

  A golf club 10 of the present embodiment includes the shaft 1, a grip 11 attached to one end of the shaft 1, and a golf club head 12 attached to the other end of the shaft 1. Accordingly, it is possible to obtain the golf club 10 that can reduce the EI at the hand of the shaft 1 that is one of the bent positions desired by the golfer while ensuring the strength of the shaft 1.

  Examples of the present invention will be described below in comparison with comparative examples. In addition, the same reference number is attached | subjected to the part which is the same as that of the above, or the same, The description may not be repeated.

  The intensity | strength of Examples 1-7 of this invention and Comparative Examples 1-2 was measured by simulation. The structure of Examples 1-7 and Comparative Examples 1-2 is demonstrated. Examples 1-7 and Comparative Examples 1-2 are mainly different in cross-sectional shape. Referring to FIG. 9, in Example 1, five convex portions 3a are formed. Referring to FIG. 10, in Example 2, eight convex portions 3a are formed. Referring to FIG. 11, in Example 3, ten convex portions 3 a are formed. Referring to FIG. 12, in Example 4, twelve convex portions 3a are formed. Referring to FIG. 13, in Example 5, 15 convex portions 3a are formed. Referring to FIG. 14, in Example 6, 18 pieces of a plurality of convex portions 3 a are formed. Referring to FIG. 15, in Example 7, a plurality of convex portions 3a are formed. With reference to FIG. 16 and FIG. 17, in the comparative example 1 and the comparative example 2, the convex part 3a is not formed.

  Moreover, the thickness of all of Examples 1 to 7 was 0.26 mm. The wall thickness of Comparative Example 1 was 0.34 mm, and the wall thickness of Comparative Example 2 was 0.26 mm. Moreover, all of Examples 1-7 and Comparative Examples 1-2 were 13.7 mm in diameter. In addition, the diameter of Examples 1-7 is a diameter of a base.

  A measurement method will be described with reference to FIG. FIG. 18 illustrates the configuration of the fourth embodiment. In each of Examples 1 to 7 and Comparative Examples 1 and 2, the length dimension in the extending direction was 60 mm. Then, in both Examples 1 to 7 and Comparative Examples 1 and 2, both ends are fixed, and a center of the surface is applied in a state where a force F of 100 N is applied to a surface on which a circle having a diameter of 4 mm is projected at the center in the extending direction. The VM (Von Mises) stress value was measured by simulation using the finite element method.

  The simulation result is shown in FIG. Referring to FIG. 19, it was found that in Comparative Example 2, the VM stress was as large as 560 MPa, so that the strength could not be secured. On the other hand, in Examples 1-7, since VM stress was small, it turned out that intensity | strength is securable. Moreover, the VM stress of the VM stress of Comparative Example 1 is preferably 365 MPa or less. Therefore, it turned out that Examples 1-4 whose VM stress is smaller than the comparative example 1 are preferable. In Example 4, the VM stress was 340 MPa. And in Examples 1-4, it turned out that bigger intensity | strength than the comparative example 1 of thickness 0.34mm can be ensured, although it is 0.26mm thick.

  In Comparative Example 1, the strength can be ensured by a thickness of 0.34 mm, but since the second moment is increased because the thickness is thicker than those in Examples 1 to 7, EI can be reduced. Can not.

  Subsequently, with reference to FIGS. 20 and 21, EI was measured by simulation for the shafts of Examples A and B having a curved portion and the shaft of Comparative Example A having no curved portion. Here, FIG. 20 is a graph showing a change in wall thickness for each of the shafts of Examples A and B having a curved portion and the shaft of Comparative Example A having no curved portion. FIG. 21 is a graph showing the change in EI for each of the shafts of Examples A and B and the shaft of Comparative Example A. These changes in EI correspond to the changes in the wall thickness shown in FIG. Based on the simulation calculation.

  As shown in FIG. 21, the shaft of Comparative Example A has a thickness of about 0.34 mm of that of Comparative Example 1 in the vicinity of 700 mm from the tip of the shaft. As shown in FIG. 20, in Comparative Example A, the EI increases in the range from 600 mm to 800 mm from the tip of the shaft at hand.

  The shaft of Example A has the same configuration as that shown in FIG. The shaft of Example B has a configuration similar to that shown in FIG. As shown in FIG. 21, the shafts of Examples A and B have the thickness of about 0.26 mm of Examples 1 to 7 in the vicinity of the range of 600 to 800 mm from the tip of the shaft. In Example A, the thickness is the same as in Comparative Example A in the range exceeding 800 mm from the tip of the shaft.

  As shown in FIG. 20, in Examples A and B, the EI is small in the range of 600 mm or more and 800 mm or less from the tip of the shaft at hand. Therefore, in Examples A and B, it was found that the EI at the hand of the shaft, which is one of the bending positions desired by the golfer, can be reduced while securing the strength of the shaft.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Shaft, 2 Cylindrical part, 3 Curved part, 3a Convex part, 3ar, 3br Curvature radius, 3b Base part, 10 Golf club, 11 Grip, 12 Golf club head.

Claims (7)

A shaft having an outer shell,
The outer shell includes a cylindrical portion;
A curved portion having a plurality of convex portions provided continuously to the cylindrical portion and arranged side by side in the outer circumferential direction of the shaft;
The shaft, wherein the curved portion has a uniform thickness, and the plurality of convex portions extend in the extending direction of the shaft.   The shaft according to claim 1, wherein the curved portion is provided in a range of a position separated by 600 mm or more from the tip of the shaft. The curved portion includes a base that is adjacent to the plurality of convex portions in the outer peripheral direction and from which the plurality of convex portions protrude,
Each of the plurality of convex portions and the base portion has an arc shape in a cross section in a direction perpendicular to the extending direction of the shaft,
The shaft according to claim 1 or 2, wherein a radius of curvature of an outer peripheral surface of each of the plurality of convex portions is smaller than a radius of curvature of an outer peripheral surface of the base portion.   4. The center of an arc-shaped circle on the outer peripheral surface of each of the plurality of convex portions is disposed equiangularly with respect to the radial center of the shaft over the entire circumference of the shaft. Shaft.   The ratio of the maximum distance from the center in the radial direction of the shaft to the outer peripheral surface of each of the plurality of convex portions and the maximum distance to the outer peripheral surface of the base portion is 1.013 or more and 1.077 or less. Or the shaft of 4. The radius of curvature of the outer peripheral surface of each of the plurality of convex portions is 2.0 mm or more and 2.4 mm or less,
The center of the arc-shaped circle on the outer peripheral surface of each of the plurality of convex portions is a region of 4.80 mm or more and 5.65 mm or less from the radial center of the shaft toward the outer peripheral surface of each of the plurality of convex portions. The shaft according to any one of claims 3 to 5, which is located in A shaft according to any one of claims 1 to 6,
A grip attached to one end of the shaft;
A golf club comprising a golf club head attached to the other end of the shaft.