TWI901447B - Golf club body and manufacturing method thereof - Google Patents

Abstract

The present invention aims to achieve a golf club body that provides an appropriate bend for all players. Solution: A hollow tubular body 3 is provided. The body 3 has a tapered outer surface with a gradually increasing outer diameter between the tip 5 and base 7. Between the tip 5 and base 7, the body 3 includes a thin-walled portion 11 having a relatively thin wall thickness due to the change in inner diameter, and thick-walled portions 13 located axially on either side of the thin-walled portion 11, having a relatively thick wall thickness. The thin-walled portion 11 is arranged in an annular shape and has an inner diameter larger than that of the corresponding portion of a basic shape 15. The basic shape 15 is formed by line segments connecting the inner and outer diameters of the tip 5 and the inner and outer diameters of the base 7, respectively.

Description

Golf club body and manufacturing method thereof

The present invention relates to a golf club body and a manufacturing method thereof.

It is known that golf clubs can improve ball flight distance and stability by utilizing the bend of the club shaft (hereinafter referred to as the golf club shaft) during the swing.

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

However, the golf club body of Patent Document 1 requires the user to have a certain level of skill to achieve proper bend, and therefore, it may be difficult to achieve proper bend depending on the user. [Known Technical Document] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2023-63540.

[The problem that the invention aims to solve]

The problem we wanted to solve was the difficulty in achieving the appropriate curvature depending on the user. [Technical Solution]

The present invention provides a golf club body comprising: a hollow tubular body having a tapered outer surface with an outer diameter gradually increasing between a tip end and a base end; the tubular body having a thin-walled portion between the tip end and the base end, the thin-walled portion having a relatively small wall thickness due to the change in inner diameter; and thick-walled portions located axially on either side of the thin-walled portion, the thickest wall thickness being relatively large.

The present invention also provides a method for manufacturing a golf club shaft, wherein radial protrusions are positioned on the surface of a mold core, a prepreg is wound around the mold core, and the prepreg is cured to form a hollow tubular body. The tubular body has a relatively thin-walled portion corresponding to the protrusions between a distal end and a proximal end, and relatively thick-walled portions on both axial sides of the thin-walled portion. [Effects of the Invention]

The present invention can realize a golf club body that can achieve appropriate bending regardless of the user.

By providing a thin-walled portion in the middle of the golf club shaft, the goal of achieving a golf club shaft that provides the proper bend for all players is achieved.

Golf club shaft 1 includes a hollow tubular body 3 having a tapered outer surface with an outer diameter gradually increasing between a tip end 5 and a base end 7. Tube 3 includes a thin-walled portion 11 between tip end 5 and base end 7, with a relatively thin wall thickness due to the change in inner diameter, and thick-walled portions 13 located axially on either side of thin-walled portion 11 and having relatively thick walls.

The thin-walled portion 11 may be provided in an annular shape or partially provided in the circumferential direction.

The thin-walled portion 11 preferably has an inner diameter larger than that of the basic shape 15 including a line segment connecting the inner diameter of the distal end portion 5 and the inner diameter of the proximal end portion 7 .

The length of the tube 3 can be set, for example, within a range of 838 mm to 1194 mm. The position of the thin-walled portion 11 can be changed depending on the user's clubhead speed and swing habits. However, when the tube 3 is 838 mm long, it is preferably located within a range of 150 mm to 688 mm from the front end 3a of the tube 3. When the tube 3 is 1194 mm long, it is preferably located within a range of 150 mm to 1044 mm from the front end 3a of the tube 3.

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

The material of the tube 3 of the golf club shaft 1 can be any suitable material, but it can also be carbon fiber reinforced plastic.

The golf club shaft 1 is manufactured by positioning the radial protrusions 19 on the outer surface 17 a of the core 17 , wrapping the prepreg 21 around the outer surface 17 a of the core 17 , and curing the prepreg 21 to form the hollow tube 3 having the thin-walled portion 11 .

The protrusion 19 is preferably provided integrally with the mold core 17, but may also be separate from the mold core 17.

The protrusion 19 is preferably arranged in a ring shape relative to the core 17 in response to the thin-walled portion 11 of the tube 3.

Furthermore, the protrusion 19 preferably has an outer diameter larger than a basic shape 29 formed by a line segment connecting the outer diameters of the front end portion 23 and the base end portion 27 of the core 17 in response to the thin-walled portion 11 .

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

On both axial sides of the protrusion 19 there may be recesses 20 , which have an outer diameter smaller than the basic shape 29 of the die core 17 .

Depending on the material of the golf club shaft 1, the prepreg 21 may be a carbon fiber sheet impregnated with resin. [Embodiment]

[Golf Club Body Structure] Figure 1 is a schematic longitudinal cross-sectional view of a golf club body according to Example 1 of the present invention. Figure 2 is a transverse cross-sectional view taken along line II-II in Figure 1 . A longitudinal cross-sectional view refers to a cross-sectional view taken along the axis of the golf club body, while a transverse cross-sectional view refers to a cross-sectional view perpendicular to the axis.

The golf club shaft 1 shown in FIG1 is made of fiber-reinforced plastic, particularly carbon fiber-reinforced plastic, and has a hollow tubular body 3. The material of the tubular body 3 is not particularly limited and may be made of a composite material in addition to other fiber-reinforced plastics or metals.

The cross-sectional shape of the tubular body 3 is circular. However, the cross-sectional shape of the tubular body 3 may be another shape, such as an ellipse. The length of the tubular body 3 is 838 mm to 1194 mm. However, the golf club shaft 1 may be shorter than 838 mm or longer than 1194 mm, generally within the range of 838 mm to 1194 mm.

The tube body 3 is composed of a front end portion 5 , a base end portion 7 and a middle portion 9 .

The tip end 5 is the axially distal portion, encompassing a predetermined area of the tubular body 3 from the distal end 3a. In this embodiment, the tip end 5 is the portion to which the golf club head is attached. The tip end 5 has a tapered outer surface with a gradually increasing outer diameter toward the base end 3b. However, the tip end 5 may also be formed as a straight line with a constant outer diameter.

The base end portion 7 is the axial proximal portion of the tubular body 3 and refers to a predetermined area of the tubular body 3 extending from the base end 3b in the axial direction. In this embodiment, the base end portion 7 is the portion to which the grip of the golf club is attached. While the base end portion 7 has a straight outer surface with a constant outer diameter, it may also have a tapered outer surface with a gradually decreasing outer diameter toward the base end 3b.

The middle portion 9 is located between the front end portion 5 and the base end portion 7 and has a tapered outer surface whose outer diameter gradually increases slightly toward the base end 3b. Therefore, the tube body 3 has a tapered outer surface whose outer diameter gradually increases between the front end portion 5 and the base end portion 7.

The tube 3 includes a thin-walled portion 11 and a thick-walled portion 13 .

The thin-walled portion 11 is a portion having a relatively small wall thickness. The thin-walled portion 11 is disposed continuously in a circular pattern relative to the tube body 3. Alternatively, multiple thin-walled portions 11 may be disposed in a non-continuous circular pattern. Furthermore, the thin-walled portion 11 may be disposed radially away from both sides and in a non-circular pattern.

This thin-walled portion 11 has a larger inner diameter than the corresponding portion of the basic shape 15, which is defined by the outer surface of the middle portion 9 and the line segment connecting the inner diameters of the front end portion 5 and the inner diameters of the base end portion 7. As a result, the wall thickness of the thin-walled portion 11 is thinner than the corresponding portion of the basic shape 15.

The inner diameter and outer diameter of the distal end portion 5 may be any portion of the distal end portion 5. The inner diameter and outer diameter of the proximal end portion 7 may be any portion of the proximal end portion 7. Preferably, the inner diameter and outer diameter of the distal end portion 5 and proximal end portion 7 are the inner diameter and outer diameter of the boundary portion with the middle portion 9.

The thin-walled portion 11 of this embodiment has a tapered inner surface 11a whose inner diameter gradually increases axially. This results in a gradually decreasing thickness of the thin-walled portion 11. The thickness of the thinnest portion of the thin-walled portion 11 is, for example, 1.03 mm to 1.46 mm, representing 98% to 99% of the thickness of the same (corresponding) axial portion of the basic shape 15.

When the length of the tube body 3 is 838 mm to 1194 mm, the thin-walled portion 11 is located within a range of 150 mm to 1044 mm from the front end 3a of the tube body 3. More preferably, the thin-walled portion 11 is located within a 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 thin-walled portion 11 is preferably located within a range of 150 mm to 688 mm from the front end 3a of the tube body 3. When the length of the tube body 3 is 1194 mm, the thin-walled portion 11 is preferably located within a range of 150 mm to 1044 mm from the front end 3a of the tube body 3.

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

Thick-walled portions 13 are located axially on either side of thin-walled portion 11 and are relatively thick. Thick-walled portions 13 are arranged continuously and annularly relative to tube body 3. However, multiple thick-walled portions 13 may be arranged non-continuously in an annular pattern. Furthermore, thick-walled portions 13 may be arranged away from the radial sides and non-annularly.

This thick-walled portion 13 has a smaller inner diameter than the corresponding portion of the basic shape 15 of the tube body 3. Thus, the thick-walled portion 13 is thicker than 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 and may also be of the same thickness as the corresponding portion of the basic shape.

The thick-walled portion 13 of this embodiment has a tapered inner surface 13a whose inner diameter tapers axially from both sides. This results in a gradually increasing thickness of the thick-walled portion 13 from both sides. The thickness of the thickest portion of the thick-walled portion 13 is, for example, 1.06 mm to 1.56 mm, representing 101% to 105% of the thickness of the same (corresponding) axial portion of the basic shape 15.

The position of the thick-walled portion 13 only needs to be in the area adjacent to the thin-walled portion 11 in the axial direction. 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). 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.

Furthermore, the number of thick-walled portions 13 and thin-walled portions 11 can be arbitrarily set. For example, two or more thin-walled portions 11 can be provided, and three or more thick-walled portions 13 can be provided.

[Golf Club Shaft Function] Figures 3(A) and 3(B) are schematic diagrams illustrating the bending and bending recovery of a golf club shaft 1. Figure 3(A) illustrates an embodiment, while Figure 3(B) illustrates a comparative example. Figure 4 is a cross-sectional view illustrating the compression of the thin-walled portion 11. The comparative example in Figure 3(B) is identical to the golf club shaft 1 of Example 1, except that it lacks the thin-walled portion 11 and the thick-walled portion 13.

In the golf club shaft 1 of this embodiment, the thin-walled portion 11 is easily compressed when the player swings the club. Compression refers to compressing the tubular body 3 radially inward in the cross-section of the golf club shaft 1. In this embodiment, the cross-sectional shape of the tubular body 3 is flattened to form an elliptical shape.

Specifically, as shown in FIG3(A) , the golf club body 1 undergoes bending and bending recovery during the swing. The bending is a gradual deformation toward the tip end 5 and toward the rear in the swing direction, while the bending recovery is a gradual deformation toward the tip end 5 and toward the front in the swing direction, in the opposite direction of the bending.

As shown in Figures 1, 3(A), and 4, the golf club shaft 1 of this embodiment bends first, while being compressed and flexed, due to the presence of the thicker portions 13 on either side of the thin-walled portion 11. At this time, the thin-walled portion 11 is thinner than the corresponding portion of the basic shape 15 and is therefore more easily compressed, so it bends first while being compressed more reliably.

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, a sudden change in wall thickness is suppressed, stress concentration is avoided, and damage is suppressed.

The bending recovery process is that the thin-walled portion 11 temporarily returns to a circular shape and then bends in the opposite direction while being compressed and bent. This bending recovery is also because the thin-walled portion 11 is easily compressed due to the presence of the thick-walled portions 13 on both sides and the thinner wall than the corresponding portion of the basic shape.

On the other hand, as shown in FIG3B , typical bending and bend recovery involve bending and bend recovery of the entire golf club body 1, not prior bending. In contrast, in this embodiment, the absolute values of the bending amount and the bend recovery amount can be reduced. Therefore, in the golf club body 1 of this embodiment, bending and bend recovery are reliably achieved and easily controlled.

Furthermore, in the golf club body 1 of this embodiment, by reducing the absolute values of the bending amount and the bending recovery amount, it is possible to suppress the dynamic clubface angle D from becoming excessively large, thereby obtaining an appropriate dynamic clubface angle D. The dynamic clubface angle D is the clubface angle actually imparted to the ball when the ball is hit.

Furthermore, in the golf club body 1 of this embodiment, since the angle of attack A becomes flatter through bending and bend 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.

Figure 5 is a graph schematically showing the compressibility of the golf club shaft 1 according to this embodiment; Figure 6 (A) is a diagram schematically illustrating the compressibility measurement method; and Figure 6 (B) is a graph showing the compressibility measurement results. A higher compressibility means greater compressibility. The compressibility is calculated by bending the golf club shaft 1 at three points, based on the deflection amount d and the bending stiffness.

Here, bending stiffness is calculated by bending the golf club body 1 over a measuring span L, as shown in Figure 6(A). The measuring span L is set to 300mm. Changing the bending amount d results in a difference in bending stiffness (bending stiffness difference) compared to before the change, as shown in Figure 6(B). This is because compression occurs, as shown in Figure 4, and the greater the bending amount d, the greater the effect. This bending stiffness difference is defined as compression.

As shown in FIG. 5 , it can be seen that in the golf club body 1 of this embodiment, the degree of compression is greater in the thin portion 11 than on both axial sides thereof.

FIG7(A) and FIG7(B) are graphs showing the results of trial shots by different users. User A's club head speed is 43.5 m/s, and User B's club head speed is 39.9 m/s.

FIG7(A) and FIG7(B) show error ellipses based on plots of the results of test hits with the golf club shaft 1 of the embodiment and the golf club shaft of the comparative example. The comparative example is identical to the golf club shaft 1 of the embodiment 1 except that it lacks the thin-walled portion 11 and the thick-walled portion 13.

As shown in FIG. 7(A) and FIG. 7(B), when any user tries to hit the golf club body 1 according to the embodiment, the error ellipse is close to the ideal values of the dynamic clubface angle D and the attack angle A.

Figure 8 is a graph showing ideal values for dynamic loft angle D and angle of attack A. As shown in Figure 8, these ideal values are used to optimize the launch angle and spin for extending flight distance, and they vary depending on the clubhead speed.

As shown in FIG8 , although the ideal values differ depending on the club head speed, in the golf club body 1 of the embodiment, both users A and B having different club head speeds can bring the dynamic club face angle D and the attack angle A close to the ideal values.

Thus, the golf club shaft 1 of this embodiment includes a hollow tubular body 3 having a tapered outer surface whose outer diameter gradually increases between the tip end 5 and the base end 7. The tubular body 3 includes a thin-walled portion 11 between the tip end 5 and the base end 7, whose wall thickness is relatively small due to the change in inner diameter, and thick-walled portions 13 located axially on either side of the thin-walled portion 11 and having relatively large wall thicknesses.

Therefore, in the golf club shaft 1, the tube 3 bends and recovers its bend first in the thin portion 11, allowing for appropriate bending regardless of the user. Furthermore, in the golf club shaft 1, the absolute values of the bending amount and the bending recovery amount can be reduced, ensuring reliable bending and bending recovery, and making them easier to control.

Since the thin-walled portion 11 is arranged in an annular shape, compression can be performed smoothly.

Since the thin-walled portion 11 has a larger inner diameter than the corresponding portion of the basic shape 15, the basic shape 15 is formed by 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, compression can be performed reliably, and the appropriate bend can be obtained regardless of the user.

Furthermore, when the length of the tube body 3 is 838 mm to 1194 mm, the thin-walled portion 11 is within the range of 150 mm to 1044 mm from the front end 3a of the tube body 3, so that the user can obtain an appropriate bend regardless of the user's preference.

[Golf Club Shaft Manufacturing Method] Figures 9(A) to 9(C) are longitudinal cross-sectional views illustrating a method for manufacturing a golf club shaft 1. Figure 9(A) shows a mold core, Figure 9(B) shows a prepreg wound around the mold core in Figure 9(A), and Figure 9(C) shows a film wound around the prepreg in Figure 9(B).

In the method for manufacturing the golf club shaft 1 of this embodiment, as shown in FIG. 9(A) and FIG. 9(B) , the radial protrusions 19 are positioned on the outer surface 17 a of the core 17 , and the prepreg 21 is wound around the outer surface 17 a of the core 17 .

The die core 17 is rod-shaped, with the outer diameter of the surface gradually increasing from the front end toward the base end. The die core 17 of this embodiment corresponds to the golf club shaft 1 and includes a front end 23, a middle portion 25, and a base end 27. The front end 23 has an outer surface with an outer diameter gradually increasing from the front end 17b, the middle portion 25 has a protrusion 19 and a recess 20, and the base end 27 has an outer surface with an outer diameter that remains constant toward the base end 17c.

The protrusion 19 is formed integrally with the core 17 in this embodiment, but may be formed separately. The shape of the protrusion 19 has a shape that fits into the thin-walled portion 11. Therefore, the protrusion 19 of this embodiment is arranged in a ring shape, and the outer diameter gradually increases from both sides of the axis. This protrusion 19 has a larger 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 of the core 17 and the outer diameter of the base end portion 27. Moreover, 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 ranging from the front end 3a to 150 mm to 1044 mm in length.

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 ranging from 150 mm to 688 mm in length from the front end 3a. 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 ranging from 150 mm to 1044 mm in length from the front end 3a.

Recesses 20 are located on either axial side of protrusion 19, corresponding to thick-walled portion 13 and continuing from the outer surface of protrusion 19, where the outer diameter gradually decreases. These recesses 20 have a smaller outer diameter than the corresponding portion of basic shape 29, which is formed by a line segment connecting the outer diameters of tip 23 and base 27 of core 17.

Multiple prepregs 21 having predetermined cut shapes and dimensions are wound around the die 17. The prepregs 21 are wound along the outer surface of the die 17 having the protrusions 19. FIG10 shows a developed view of the prepregs 21. In the example of FIG10 , six prepregs 21 are used. The number of prepregs 21 can be appropriately set depending on the characteristics of the golf club body 1.

Each prepreg 21 is a fiber sheet impregnated with a resin. The resin is not particularly limited, but is an epoxy resin, an unsaturated polyester resin, a phenolic resin, or the like. The fiber sheet may be, for example, a sheet of inorganic fibers such as metal fiber, boron fiber, carbon fiber, glass fiber, ceramic fiber, polyarylamide fiber, or other high-strength synthetic fibers. Inorganic fibers are preferably used because they are lightweight and high-strength. Among them, carbon fiber is the best because of its superior specific strength and specific rigidity. Therefore, in this embodiment, a carbon fiber sheet is used as the fiber sheet.

After the prepreg 21 is wrapped around the mold core 17, as shown in Figure 9(C), a film 31 is further wrapped around the mold core 17 to maintain the prepreg 21 wrapped around the mold core 17. In this state, the prepreg 21 is hardened by heating, resulting in a tubular semi-finished product. After the film 31 is removed, the semi-finished product is polished and becomes the tubular body 3 of the golf club shaft 1 shown in Figure 1.

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

Thus, a golf club body 1 that can achieve appropriate bending for all players can be achieved.

1: Golf club body 3: Tube 3a: Tip 3b: Base 5: Tip (tube) 7: Base (tube) 9: Middle (tube) 11: Thin-walled section 11a: Inner surface 13: Thick-walled section 13a: Inner surface 15: Basic shape (tube) 17: Core 17a: Outer surface 17b: Tip 17c: Base 19: Protrusion 20: Recess 21: Prepreg 23: Tip (core) 25: Middle (core) 27: Base (core) 29: Basic shape (core) 31: Film A: Angle of attack D: Dynamic loft angle d: Deflection L: Measurement span S: Rotation angle W: Load

Figure 1 is a schematic longitudinal cross-sectional view of a golf club body according to an embodiment of the present invention. Figure 2 is a cross-sectional view taken along line II-II in Figure 1. Figures 3 (A) and (B) are schematic diagrams illustrating the bending and bending recovery of a golf club body, with Figure 3 (A) illustrating an embodiment and Figure 3 (B) illustrating a comparative example. Figure 4 is a cross-sectional view illustrating the compression of the thin-walled portion of the golf club body in Figure 1. Figure 5 is a graph schematically illustrating the degree of compression of the thin-walled portion of the golf club body in Figure 1. Figure 6(A) is a schematic diagram illustrating the compression measurement method, and Figure 6(B) is a graph showing the compression measurement results. Figures 7(A) and 7(B) are graphs showing the results of test shots by different users, respectively. Figure 8 is a graph showing ideal values for the dynamic angle and angle of attack. Figures 9(A) to 9(C) are longitudinal cross-sectional views illustrating a method for manufacturing a golf club shaft 1. Figure 9(A) shows a mold core, Figure 9(B) shows a prepreg wound around the mold core in Figure 9(A), and Figure 9(C) shows a film wound around the prepreg in Figure 9(B). Figure 10 is a developed view showing an example of the prepreg in Figure 9.

1: Golf club body

3: Tube body

3a: Front-end

3b: Base end

5: Front end (tube)

7: Base end (tube)

9: Middle part (tube body)

11: Thin-walled section

11a: Inner surface

13: Thick wall section

13a: Inner surface

15: Basic shape (tube)

Claims (13)

A golf club shaft comprises a hollow tubular body having a tapered outer surface with a gradually increasing outer diameter in a middle portion between a front end and a base end. The tubular body has a thin-walled portion in the middle portion having a relatively small wall thickness due to a change in inner diameter, and thick-walled portions located axially on either side of the thin-walled portion having a relatively large wall thickness. The golf club body as described in claim 1, wherein the thin-walled portion is arranged in a ring shape. A golf club body as described in claim 2, wherein the thin-walled portion has an inner diameter larger than a corresponding portion of a basic shape, and the basic shape includes a line segment connecting the inner diameter of the front end portion at a boundary portion relative to the middle portion and the inner diameter of the base end portion. A golf club shaft as described in claim 3, wherein the length of the aforementioned tube is 838 mm to 1194 mm, and the aforementioned thin-walled portion is located within a range of 150 mm to 688 mm from the front end of the aforementioned tube when the length of the aforementioned tube is 838 mm, and is located within a range of 150 mm to 1044 mm from the front end of the aforementioned tube when the length of the aforementioned tube is 1194 mm. The golf club body as described in claim 3, wherein the thick-walled portion has a smaller inner diameter than a corresponding portion of the basic shape. A golf club body as described in any one of claims 1 to 5, wherein the tube is composed of carbon fiber reinforced plastic. A method for manufacturing a golf club shaft comprises providing radial protrusions on the surface of a mold core, wrapping a prepreg around the mold core, and curing the prepreg to form a hollow tubular body. The tubular body has a relatively thin-walled portion corresponding to the protrusions in the middle portion between the front end and the base end, and relatively thick-walled portions on both axial sides of the thin-walled portion. The method for manufacturing a golf club shaft as described in claim 7, wherein the protrusion is provided integrally with the mold core. The method for manufacturing a golf club shaft as described in claim 7, wherein the protrusion is arranged in a ring shape relative to the mold core. A method for manufacturing a golf club shaft as described in claim 7, wherein the protrusion has an outer diameter larger than a corresponding portion of a basic shape, and the basic shape includes a line segment connecting the outer diameter of the front end portion of the mold core and the outer diameter of the base end portion. A method for manufacturing a golf club shaft as described in claim 7, wherein the length of the aforementioned tube is 838 mm to 1194 mm, and the aforementioned protrusion is located within a range of 150 mm to 688 mm from the front end of the aforementioned tube when the length of the aforementioned tube is 838 mm, and is located within a range of 150 mm to 1044 mm from the front end of the aforementioned tube when the length of the aforementioned tube is 1194 mm. A method for manufacturing a golf club shaft as described in claim 7, wherein there are recesses on both axial sides of the protrusion, the recesses having an outer diameter smaller than a corresponding portion of a basic shape, and the basic shape includes a line segment connecting the outer diameter of the front end portion of the mold core and the outer diameter of the base end portion. The method for manufacturing a golf club shaft as described in any one of claims 7 to 12, wherein the prepreg is a carbon fiber sheet impregnated with a resin.