Golf club shaft and its manufacturing method

Abstract

This invention provides a golf club shaft that allows for appropriate bending regardless of the user. It comprises a hollow tubular body (3) having a tapered outer surface with an outer diameter that gradually increases between the front end (5) and the base end (7). The tube (3) has a thin-walled portion (11) with a relatively small wall thickness due to the change in inner diameter between the front end (5) and the base end (7), and a thick-walled portion (13) with a relatively large wall thickness located on both axial sides of the thin-walled portion (11). The thin-walled portion (11) is arranged in a circumferential shape and has an inner diameter larger than the corresponding part of the basic shape (15). The basic shape (15) is composed of line segments that connect the inner and outer diameters of the front end (5) and the inner and outer diameters of the base end (7), respectively.

Description

Technical Field

[0001] This invention relates to a golf club shaft and a method for manufacturing the same. Background Technology

[0002] It is known that golf clubs can increase the ball's flight distance and stability by utilizing the bending of the club body (hereinafter referred to as the golf club shaft) during the swing.

[0003] For example, Patent Document 1 discloses a golf club shaft that can bend appropriately and extend the flight distance of the ball by setting the vibration number, weight and the position of the inflection point.

[0004] However, the golf club shaft of Patent Document 1 can only be properly bent when the user has a certain skill level, so it is difficult to achieve proper bending depending on the user.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2023-63540 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] The problem to be solved is that it is difficult to achieve the appropriate bending depending on the user.

[0010] Solution for solving the problem

[0011] The present invention provides a golf club shaft comprising: a hollow tube having a tapered outer surface with an outer diameter that gradually increases between a front end and a base end; the tube having a thin-walled portion with relatively small wall thickness due to a change in inner diameter and a thick-walled portion with relatively large wall thickness located on both axial sides of the thin-walled portion between the front end and the base end.

[0012] Furthermore, the present invention provides a method for manufacturing a golf club shaft, wherein radial protrusions are located on the surface of a core, and a prepreg is wound around the surface of the core, and a hollow tube is formed by hardening the prepreg. The tube has a thin-walled portion with relatively small wall thickness in the portion corresponding to the protrusion between the front end and the base end, and thick-walled portions with relatively large wall thickness on both axial sides of the thin-walled portion.

[0013] Invention Effects

[0014] In this invention, a golf club shaft with a suitable bend can be achieved regardless of the user. Attached Figure Description

[0015] Figure 1 This is a schematic longitudinal sectional view of the golf club shaft according to an embodiment of the present invention.

[0016] Figure 2 for Figure 1 A cross-sectional view of line II-II.

[0017] Figure 3 (A) and (B) are schematic diagrams representing the bending and flex recovery of a golf club shaft. Figure 3 (A) is an example. Figure 3 (B) is a comparative example.

[0018] Figure 4 To indicate Figure 1 A compressed cross-sectional view of the thin-walled portion of a golf club shaft.

[0019] Figure 5 To represent in a general way Figure 1 A chart showing the compression of the thin-walled portion of a golf club shaft.

[0020] Figure 6 (A) is a schematic diagram representing a method for measuring compressibility. Figure 6 (B) is a graph showing the measurement results of compressibility.

[0021] Figure 7 (A) and Figure 7 (B) is a chart representing the results of different users' test runs.

[0022] Figure 8 A chart representing the ideal values ​​of dynamic angle and angle of attack.

[0023] Figure 9 (A) ~ Figure 9 (C) is a longitudinal sectional view showing the manufacturing method of the golf club shaft 1. Figure 9 (A) is the mold core. Figure 9 (B) is in Figure 9 (A) The state of the mold core wound with the prepreg. Figure 9 (C) is in Figure 9 The state of the prepreg of (B) wound tape.

[0024] Figure 10 To indicate Figure 9 An example of a prepreg unfolded diagram. Detailed Implementation

[0025] By incorporating a thin-walled section in the middle of the golf club shaft, the goal of achieving a golf club shaft with appropriate bending that can be achieved regardless of the user is achieved.

[0026] The golf club shaft 1 has a hollow tubular body 3, which has a tapered outer surface whose outer diameter gradually increases between the front end 5 and the base end 7. The tube 3 has a thin-walled portion 11 and a thick-walled portion 13 between the front end 5 and the base end 7. The thin-walled portion 11 has a relatively small wall thickness. The thick-walled portions 13 are located on both axial sides of the thin-walled portion 11 and have a relatively large wall thickness.

[0027] The thin-walled portion 11 can be arranged in a circumferential shape or in a circumferential portion.

[0028] The thin-walled portion 11 preferably has an inner diameter larger than that of the basic shape 15, which includes a line segment connecting the inner diameter of the front end portion 5 and the inner diameter of the base end portion 7.

[0029] The length of the tube body 3 can be set, for example, in the range of 838mm to 1194mm. The position of the thin-walled portion 11 can be changed according to the user's clubhead speed or swing habits. When the length of the tube body 3 is 838mm, it is preferably located in the range of 150mm to 688mm from the front end 3a. When the length of the tube body 3 is 1194mm, it is preferably located in the range of 150mm to 1044mm from the front end 3a.

[0030] The thick-walled portion 13 may have a smaller inner diameter than the basic shape 15.

[0031] The tube 3 of the golf club shaft 1 can be made of an appropriate material, but it can also be carbon fiber reinforced plastic.

[0032] The golf club shaft 1 is manufactured by placing radial protrusions 19 on the outer surface 17a of the core 17 and winding a prepreg 21 around the outer surface 17a of the core 17, thereby forming a hollow tube 3 with a thin-walled portion 11 by hardening the prepreg 21.

[0033] The protrusion 19 is preferably integrated with the mold core 17, but it can also be separate from the mold core 17.

[0034] The protrusion 19 is preferably arranged in a surrounding shape relative to the mold core 17 based on the thin-walled portion 11 of the tube body 3.

[0035] Furthermore, the protrusion 19 preferably has a larger outer diameter than the basic shape 29 according to the thin-walled portion 11, which is formed by a line segment connecting the outer diameter of the front end portion 23 and the outer diameter of the base end portion 25 of the mold core 17.

[0036] The protrusion 19 is preferably based on the thin-walled portion 11, and when the length of the tube body 3 is 838 mm, it is located in the range of 150 mm to 688 mm from the front end 3a of the tube body 3, and when the length of the tube body 3 is 1194 mm, it is located in the range of 150 mm to 1044 mm from the front end 3a of the tube body 3.

[0037] Recesses 20 may be present on both sides of the protrusion 19, the recesses 20 having an outer diameter smaller than the basic shape 29 of the mold core 17.

[0038] The prepreg 21 can be a carbon fiber sheet impregnated with resin, depending on the material of the golf club body 1.

[0039] Example

[0040] [The construction of a golf club shaft]

[0041] Figure 1 This is a schematic longitudinal sectional view of the golf club shaft according to Embodiment 1 of the present invention. Figure 2 for Figure 1 The cross-sectional view along line II-II. Furthermore, the longitudinal section refers to the section along the axial direction of the golf club shaft, while the cross section is a section orthogonal to the axial direction.

[0042] Figure 1 The golf club shaft 1 is made of fiber-reinforced plastic, especially carbon fiber reinforced plastic, and has a hollow tube 3. In addition, the material of the tube 3 is not particularly limited, and it can be made of other fiber-reinforced plastics or metals, or it can be a composite material.

[0043] The cross-sectional shape of the tube body 3 is circular. However, the cross-sectional shape of the tube body 3 can also be other shapes such as ellipse. The length of the tube body 3 is 838mm to 1194mm. However, the golf club shaft 1 can also be set to be shorter than 838mm or longer than 1194mm, roughly in the range of 838mm to 1194mm.

[0044] The tube body 3 is composed of a front end 5, a base end 7, and a middle part 9.

[0045] The front end portion 5 is the axial front end portion, referring to the area within a predetermined range in the axial tube 3 starting from the front end 3a. In this embodiment, the front end portion 5 is the portion on which the club head of a golf club is mounted. This front end portion 5 has a tapered outer surface whose outer diameter gradually increases slightly towards the base end 3b. However, the front end portion 5 may also be formed as a straight line with a constant outer diameter.

[0046] The base end portion 7 is the axial base end portion of the tube body 3, referring to the area within a predetermined range of the axial tube body 3 starting from the base end 3b. In this embodiment, the base end portion 7 is the portion on which the grip of a golf club is mounted. This base end portion 7 has a straight outer surface with a constant outer diameter. However, it may also be a tapered outer surface with the outer diameter gradually changing slightly towards the base end 3b.

[0047] The middle portion 9 is the part located between the front end portion 5 and the base end portion 7, and has a tapered outer surface whose outer diameter gradually increases towards the base end 3b. Therefore, the tube body 3 has a structure with a tapered outer surface whose outer diameter gradually increases between the front end portion 5 and the base end portion 7.

[0048] The tube body 3 has a thin-walled portion 11 and a thick-walled portion 13.

[0049] The thin-walled portion 11 is a portion with a relatively small wall thickness. The thin-walled portion 11 is continuously arranged in a circumferential shape relative to the tube body 3. In addition, multiple thin-walled portions 11 can also be arranged discontinuously in a circumferential shape. Furthermore, the thin-walled portions 11 can also be arranged away from the radial sides and in a non-circumferential shape.

[0050] The thin-walled portion 11 has a larger inner diameter than the corresponding portion of the basic shape 15. As a result, the wall thickness of the thin-walled portion 11 is thinner than that of the corresponding portion of the basic shape 15. The basic shape 15 is divided by a line segment (straight line) connecting the outer surface of the intermediate portion 9 with the inner diameter of the front end portion 5 and the inner diameter of the base end portion 7.

[0051] Furthermore, the inner and outer diameters of the front end portion 5 can be any part of the front end portion 5. The inner and outer diameters of the base end portion 7 can also be any part of the base end portion 7. Preferably, the inner and outer diameters of the front end portion 5 and the base end portion 7 are the inner and outer diameters of the boundary portion with the middle portion 9.

[0052] In this embodiment, the thin-walled portion 11 has a tapered inner surface 11a that gradually increases in inner diameter from both axial sides. Consequently, the wall thickness of the thin-walled portion 11 gradually decreases from both axial sides. The wall thickness of the thinnest portion of the thin-walled portion 11 is, for example, 1.03 mm to 1.46 mm, and is 98% to 99% of the wall thickness in the same axial region (corresponding region) of the basic shape 15.

[0053] Regarding the location of the thin-walled portion 11, when the length of the tube body 3 is 838 mm to 1194 mm, it is in the range of 150 mm to 1044 mm from the front end 3a. More preferably, the location of the thin-walled portion 11 is in the range of 12% to 88% of the total length of the tube body 3. When the length of the tube body 3 is 838 mm, the location of the thin-walled portion 11 is preferably in the range of 150 mm to 688 mm from the front end 3a. When the length of the tube body 3 is 1194 mm, the location of the thin-walled portion 11 is preferably in the range of 150 mm to 1044 mm from the front end 3a.

[0054] In this embodiment, the thinnest part of the thin-walled portion 11 is located in a length of 455 mm (39% of the length of the tube body 3 from the front end 3a) from the front end 3a, and the thin-walled portion 11 as a whole is located in a length of 392 mm to 597 mm (33% to 52% of the total length of the tube body 3) from the front end.

[0055] The thick-walled portions 13 are located on both axial sides of the thin-walled portions 11, and are portions with relatively large wall thickness. Each thick-walled portion 13 is continuously arranged in a circumferential shape relative to the tube body 3. However, multiple thick-walled portions 13 can also be arranged discontinuously in a circumferential shape. Furthermore, the thick-walled portions 13 can also be arranged in a non-circumferential shape away from the radial sides.

[0056] The thick-walled portion 13 has a smaller inner diameter than the corresponding portion of the basic shape 15 of the tube body 3. Therefore, the wall thickness of the thick-walled portion 13 is greater than that of the corresponding portion of the basic shape 15. However, the thick-walled portion 13 only needs to be at least thicker than the thin-walled portion 11, or it can have the same wall thickness as the corresponding portion of the basic shape 15.

[0057] In this embodiment, the thick-walled portion 13 has a tapered inner surface 13a whose inner diameter gradually decreases from both sides of the axial direction. Consequently, the wall thickness of the thick-walled portion 13 gradually increases from both sides of the axial direction. The wall thickness of the thickest part of the thick-walled portion 13 is, for example, 1.06 mm to 1.56 mm, and is 101% to 105% of the wall thickness at the same location (corresponding location) in the axial direction of the basic shape 15.

[0058] The thick-walled portion 13 can be located in the region axially adjacent to the thin-walled portion 11. In this embodiment, the thickest part of the thick-walled portion 13 is located in the range of 330 mm (28% of the length of the tube body 3 from the front end 3a) and 740 mm (64% of the length of the tube body 3 from the front end 3a) from the front end 3a. The entire thick-walled portion 13 is located in the range of 155 mm to 392 mm (13% to 33% of the total length of the tube body 3) and 597 mm to 900 mm (52% to 77% of the total length of the tube body 3) from the front end.

[0059] Furthermore, the number of thick-walled portions 13 and thin-walled portions 11 can be set arbitrarily, for example, two or more thin-walled portions 11 and three or more thick-walled portions 13.

[0060] [The function of a golf club shaft]

[0061] Figure 3 (A) and Figure 3 (B) is a schematic diagram showing the bending and recovery of the golf club shaft 1. Figure 3 (A) is an example. Figure 3 (B) is a comparative example. Figure 4 This is a cross-sectional view showing the compression of the thin-walled portion 11. Furthermore, Figure 3 The comparative example (B) is the same as the golf club body 1 of Embodiment 1 except that it does not have the thin-walled portion 11 and the thick-walled portion 13.

[0062] In the golf club shaft 1 of this embodiment, the thin-walled portion 11 is easily compressed when the user swings the club. Compression refers to the radial inward compression of the tube 3 in the cross-section of the golf club shaft 1, and in this embodiment, the cross-sectional shape of the tube 3 is deformed into an elliptical shape and flattened.

[0063] Specifically, in the golf club shaft 1, such as Figure 3 As shown in (A), flex and flex recovery occur during the swing. Flex is a gradual deformation toward the front end 5 and toward the rear in the swing direction, while flex recovery is the opposite of flex, a gradual deformation toward the front end 5 and toward the front in the swing direction.

[0064] In this embodiment, the golf club shaft 1 is as follows: Figure 1 , Figure 3 (A) and Figure 4 As shown, during bending, the thin-walled portion 11 bends first in a manner that involves compression and bending simultaneously due to the presence of the thick-walled portions 13 on both sides. At this time, since the thin-walled portion 11 is thinner than the corresponding portion of the basic shape 15 and is therefore easier to compress, it bends first more reliably while being compressed.

[0065] Furthermore, in the golf club body 1, since the wall thickness gradually increases from the thin-walled portion 11 to the thick-walled portion 13, the abrupt change in wall thickness is suppressed, stress concentration is avoided, and damage can be suppressed.

[0066] Bending recovery is the process where the thin-walled portion 11 temporarily returns to a circular shape and then bends again in the opposite direction while simultaneously compressing and buckling. This bending recovery is also due to the presence of the thick-walled portions 13 on both sides and the fact that the thin-walled portion 11 is thinner than the corresponding portion of the basic shape, making it easier to compress.

[0067] On the other hand, general bending and bending recovery, such as Figure 3 As shown in (B), it is not a preliminary bend, but rather the overall bend and recovery of the golf club body 1. Compared to that case, in this embodiment, the absolute values ​​of the bend amount and the recovery amount can be reduced. Therefore, in the golf club body 1 of this embodiment, bend and recovery are reliably obtained and easily controlled.

[0068] Furthermore, in the golf club body 1 of this embodiment, by reducing the absolute values ​​of the bending amount and the bending recovery amount, the excessive increase of the dynamic clubface angle D can be suppressed, thereby obtaining an appropriate dynamic clubface angle D. The dynamic clubface angle D is the clubface angle actually given to the ball at the time of impact.

[0069] Furthermore, in the golf club shaft 1 of this embodiment, since the angle of attack A becomes gentler due to bending and bending recovery, the spin angle S can be suppressed. The angle of attack A is the angle of incidence relative to the ball, and the spin angle S is the angle formed by the angle of attack A and the dynamic clubface angle D. As a result, the amount of spin can be reduced.

[0070] Figure 5 A diagram illustrating the compression of the golf club body 1 in this embodiment is provided for general purposes. Figure 6 (A) is a schematic diagram representing a method for measuring compressibility. Figure 6 (B) is a graph representing the measurement results of compressibility. Higher compressibility means easier compression. As compressibility, it is calculated based on the deflection and bending stiffness at three points on the golf club shaft 1.

[0071] Here, bending stiffness is as follows: Figure 6 As shown in (A), the golf club shaft 1 is deflected by measuring the span L, and the load at this time is measured and calculated. Furthermore, the measuring span L is set to 300 mm. If the amount of deflection is changed, then... Figure 6 As shown in (B), a difference in bending stiffness (bending stiffness difference) occurs relative to before the change in deflection. This is because, as Figure 4 The diagram shows that compression occurs, and the greater the deflection, the greater the effect. This difference in bending stiffness is defined as the degree of compression.

[0072] like Figure 5 As shown, in the golf club body 1 of this embodiment, the compressibility is increased in the thin-walled portion 11 compared to the two axial sides.

[0073] Figure 7 (A) and Figure 7 (B) is a graph showing the results of test shots by different users. User A's clubhead speed was 43.5 m / s, and User B's clubhead speed was 39.9 m / s.

[0074] exist Figure 7 (A) and Figure 7 In (B), the error ellipse is represented by a depiction based on the results of test hits of the golf club body 1 of the embodiment and the golf club body of the comparative example. The comparative example is identical to the golf club body 1 of Embodiment 1 except that it does not have the thin-walled portion 11 and the thick-walled portion 13.

[0075] like Figure 7 (A) and Figure 7 As shown in (B), when any user tests the golf club body 1 of the embodiment, the error ellipse is close to the ideal values ​​of the dynamic clubface angle D and the angle of attack A.

[0076] Figure 8A graph representing the ideal values ​​of the dynamic face angle D and angle of attack A. For example... Figure 8 As shown, the ideal values ​​are used to optimize the launch angle and rotation for extending flight distance, and vary depending on the stick speed.

[0077] like Figure 8 As shown, although the ideal values ​​vary depending on the speed of each clubhead, in the golf club body 1 of the embodiment, either user A or B with different clubhead speeds can make the dynamic face angle D and angle of attack A close to the ideal values.

[0078] Thus, the golf club shaft 1 of this embodiment has a hollow tube 3, which has a tapered outer surface with an outer diameter that gradually increases between the front end 5 and the base end 7. The tube 3 has a thin-walled portion 11 with a relatively small wall thickness due to the change in inner diameter between the front end 5 and the base end 7, and a thick-walled portion 13 with a relatively large wall thickness located on both axial sides of the thin-walled portion 11.

[0079] Therefore, in the golf club body 1, the tube 3 bends and recovers first in the thin-walled portion 11, allowing for appropriate bending regardless of the user. Furthermore, in the golf club body 1, since the absolute values ​​of the bending and recovery amounts can be reduced, bending and recovery are reliably achieved and easily controlled.

[0080] Because the thin-walled portion 11 is arranged in a surrounding shape, compression can be performed smoothly.

[0081] Since the thin-walled portion 11 has a larger inner diameter than the corresponding portion of the basic shape 15, which is composed of line segments connecting the inner and outer diameters of the front end portion 5 and the inner and outer diameters of the base end portion 7 respectively, it can be reliably compressed and bend appropriately regardless of the user.

[0082] Furthermore, since the thin-walled portion 11 is located in the range of 150mm to 1044mm from the front end 3a of the tube body 3 when the length of the tube body 3 is 838mm to 1194mm, it can be bent appropriately by users.

[0083] [Manufacturing method of golf club shaft]

[0084] Figure 9 (A) ~ Figure 9 (C) is a longitudinal sectional view showing the manufacturing method of the golf club shaft 1. Figure 9 (A) is the mold core. Figure 9 (B) is in Figure 9 (A) The state of the mold core wound with the prepreg. Figure 9 (C) is in Figure 9 The state of the prepreg of (B) wound tape.

[0085] In the manufacturing method of the golf club shaft 1 in this embodiment, as follows: Figure 9 (A) and Figure 9 As shown in (B), the radial protrusion 19 is located on the outer surface 17a of the mold core 17, and the prepreg 21 is wound around the outer surface 17a of the mold core 17.

[0086] The core 17 is rod-shaped, with its outer diameter gradually increasing from the front end to the base end. In this embodiment, the core 17 corresponds to the golf club body 1 and has a front end 23, a middle portion 25, and a base end 27. The front end 23 has an outer surface with a constant outer diameter from the front end 17b. The middle portion 25 has a protrusion 19 and a recess 20. The base end 27 has an outer surface with an outer diameter that gradually increases towards the base end 17c.

[0087] In this embodiment, the protrusion 19 is integrally formed with the mold core 17, but it can also be formed separately. The protrusion 19 has a shape that fits into the thin-walled portion 11. Therefore, in this embodiment, the protrusion 19 is provided in a circumferential shape, and its outer diameter gradually increases from both sides of the axial direction. This protrusion 19 has a larger outer diameter than the corresponding portion of the basic shape 29. The basic shape 29 is formed by a line segment connecting the outer diameter of the front end portion 23 and the outer diameter of the base end portion 27. Furthermore, when the length of the tube body 3 is 838 mm to 1194 mm, the protrusion 19 is located at a position corresponding to the portion of the tube body 3 with a length of 150 mm to 1044 mm from the front end 3a.

[0088] When the length of the tube body 3 is 838 mm, the protrusion 19 is located at a position corresponding to the portion of the tube body 3 extending from the front end 3a in the range of 150 mm to 688 mm. When the length of the tube body 3 is 1194 mm, the protrusion 19 is located at a position corresponding to the portion of the tube body 3 extending from the front end 3a in the range of 150 mm to 1044 mm.

[0089] The recess 20 is located on both axial sides of the protrusion 19, corresponds to the thick-walled portion 13, and is continuous through the outer surface of the protrusion 19 whose outer diameter gradually decreases. The recess 20 has a smaller outer diameter than the corresponding portion of the basic shape 29, which is formed by a line segment connecting the outer diameter of the front end portion 23 and the outer diameter of the base end portion 27 of the mold core 17.

[0090] Multiple prepregs 21 having predetermined cut shapes and sizes are wound around the mold core 17. The winding is performed along the outer surface of the mold core 17 having protrusions 19. Figure 10 This shows the unfolded diagram of the prepreg 21. Figure 10 In this example, six prepreg pieces 21 are used. The number of prepreg pieces 21 can be appropriately set according to the characteristics of the golf club body 1.

[0091] Each prepreg 21 is a fiber sheet impregnated with resin. The resin is not particularly limited, but can be epoxy resin, unsaturated polyester resin, phenolic resin, etc. The fiber sheet can be, for example, sheet of inorganic fibers such as metal fibers, boron fibers, carbon fibers, glass fibers, and ceramic fibers, polyaramid fibers, or other high-strength synthetic fibers. Inorganic fibers are preferred due to their lightweight and high strength. Carbon fibers are the best choice due to their excellent specific strength and specific stiffness. Therefore, in this embodiment, carbon fiber sheets are used as the fiber sheet.

[0092] After the prepreg 21 is wound around the mold core 17, as Figure 9 As shown in (C), the tape 31 is further wound to maintain the prepreg 21 wound around the mold core 17. In this state, the prepreg 21 is hardened by heating to obtain a tubular semi-finished product. After removing the tape 31, the outer surface of the semi-finished product is ground to become… Figure 1 The tube 3 of the golf club shaft 1.

[0093] As described above, the tube body 3 has a thin-walled portion 11 with relatively small wall thickness in the portion corresponding to the protrusion 19 between the front end portion 5 and the base end portion 7, and thick-walled portions 13 with relatively large wall thickness on both axial sides of the thin-walled portion 11.

[0094] Therefore, it is possible to achieve a golf club shaft 1 that allows for appropriate bending regardless of the user.

[0095] Symbol Explanation

[0096] 1—Golf club shaft, 3—Tube, 5—Front end (tube), 7—Base end (tube), 9—Middle section (tube), 11—Thin wall section, 13—Thick wall section, 15—Basic shape (tube), 17—Mold core, 19—Protrusion, 21—Prepreg, 23—Front end (mold core), 25—Middle section (mold core), 27—Base end (mold core), 29—Basic shape (mold core).

Claims

1. A golf club shaft, characterized in that, It has a hollow tube body with a tapered outer surface whose outer diameter gradually increases between the front end and the base end. The tube body has a thin-walled portion with relatively small wall thickness due to changes in inner diameter between the front end and the base end, and a thick-walled portion with relatively large wall thickness located on both axial sides of the thin-walled portion.

2. The golf club shaft according to claim 1, characterized in that, The thin-walled portion is configured in a circumferential shape.

3. The golf club shaft according to claim 2, characterized in that, The thin-walled portion has an inner diameter larger than the corresponding portion of the basic shape, which includes a line segment connecting the inner diameter of the front end portion and the inner diameter of the base end portion.

4. The golf club shaft according to claim 3, characterized in that, The length of the tube is 838mm to 1194mm. When the length of the tube body is 838 mm, the thin-walled portion is located in the range of 150 mm to 688 mm from the front end of the tube body. When the length of the tube body is 1194 mm, the thin-walled portion is located in the range of 150 mm to 1044 mm from the front end of the tube body.

5. The golf club shaft according to claim 2, characterized in that, The thick-walled portion has a smaller inner diameter than the corresponding portion of the basic shape, which includes a line segment connecting the inner diameter of the front end portion and the inner diameter of the base end portion.

6. The golf club shaft according to any one of claims 1 to 5, characterized in that, The tube is made of carbon fiber reinforced plastic.

7. A method for manufacturing a golf club shaft, characterized in that, The radial protrusions are positioned on the surface of the mold core, and the prepreg is wound around the surface of the mold core. A hollow tube is formed by hardening the prepreg. Between the front end and the base end, the tube body has a thin-walled portion with relatively small wall thickness in the part corresponding to the protrusion, and thick-walled portions with relatively large wall thickness on both sides of the thin-walled portion along the axial direction.

8. The method for manufacturing a golf club shaft according to claim 7, characterized in that, The protrusion is integrally formed with the mold core.

9. The method for manufacturing a golf club shaft according to claim 7, characterized in that, The protrusion is arranged in a surrounding shape relative to the mold core.

10. The method for manufacturing a golf club shaft according to claim 7, characterized in that, The protrusion has a larger outer diameter than the corresponding portion of the basic shape, which includes a line segment connecting the outer diameter of the front end of the mold core and the outer diameter of the base end.

11. The method for manufacturing a golf club shaft according to claim 7, characterized in that, The length of the tube is 838mm to 1194mm. When the length of the tube body is 838 mm, the protrusion is located in the range of 150 mm to 688 mm from the front end of the tube body. When the length of the tube body is 1194 mm, the protrusion is located in the range of 150 mm to 1044 mm from the front end of the tube body.

12. The method for manufacturing a golf club shaft according to claim 7, characterized in that, The protrusion has recesses on both axial sides, each recess having an outer diameter smaller than the corresponding portion of the basic shape, which includes a line segment connecting the outer diameter of the front end of the mold core and the outer diameter of the base end.

13. The method for manufacturing a golf club shaft according to any one of claims 7 to 12, characterized in that, The prepreg is a carbon fiber sheet impregnated with resin.

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