Golf shaft and manufacturing method thereof

Abstract

This invention provides a golf shaft that allows an appropriate flex for any user. The shaft is provided with a hollow tubular body 3 having a tapered outer surface with the outer diameter gradually increasing between the tip end 5 and the base end 7, and the body 3 is provided, between the tip end 5 and the base end 7, with a thin-walled portion 11 having a relatively small thickness due to the change in inner diameter, and thick-walled portions 13 located on both sides of the thin-walled portion 11 in the axial direction and having a relatively large thickness, and the thin-walled portions 11 are provided in a circumferential shape and have an inner diameter larger than the corresponding portions of a basic shape 15 consisting of line segments connecting the inner and outer diameters of the tip end 5 and the base end 7, respectively.

Description

[Technical field]

[0001] The present invention relates to a golf shaft and a method for manufacturing the same. [Background technology]

[0002] It is known that a golf club can improve the flight distance and stability of a ball by utilizing the bending of its shaft (hereinafter referred to as a golf shaft) during a swing.

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

[0004] However, the golf shaft of Patent Document 1 is designed to provide an appropriate flexure for users above a certain level, so that it is difficult for some users to obtain the appropriate flexure. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2023-63540 A Summary of the Invention [Problem to be solved by the invention]

[0006] The problem it is trying to solve is the difficulty some users have in obtaining the proper flex. [Means for solving the problem]

[0007] The present invention relates to a method for manufacturing a catheter having a distal end and a proximal end. The middle part The present invention provides a golf shaft having a hollow tube having a tapered outer surface with an outer diameter gradually increasing from the center to the center of the shaft. In the middleThe inner diameter of the bearing is changed to form a thin wall portion having a relatively small thickness and a thick wall portion located on both sides of the thin wall portion in the axial direction and having a relatively large thickness. The thin-walled portion has an inner diameter larger than a corresponding portion of the basic shape including a line segment connecting the inner diameter of the tip end portion and the inner diameter of the base end portion at the boundary portion with the intermediate portion.

[0008] The present invention also provides a method for producing a method for manufacturing a semiconductor device comprising the steps of: The method for manufacturing the golf shaft includes the steps of: A method for manufacturing a golf shaft is provided by winding prepreg around a mandrel surface while positioning radial protrusions on the surface, and then curing the prepreg to form a hollow tube. Effect of the Invention

[0009] The present invention makes it possible to realize a golf shaft that allows appropriate bending to be obtained regardless of the user. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic vertical cross-sectional view of a golf shaft according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Diagram 3] 3(A) and (B) are schematic diagrams showing the bending and return of a golf shaft, with FIG. 3(A) being an example and FIG. 3(B) being a comparative example. [Figure 4] FIG. 4 is a cross-sectional view showing crushing of a thin-walled portion of the golf shaft of FIG. [Diagram 5] FIG. 5 is a graph that shows the degree of crushing of the thin-walled portion of the golf shaft of FIG. [Figure 6] FIG. 6(A) is a schematic diagram showing a method for measuring the degree of crushing, and FIG. 6(B) is a graph showing the measurement results of the degree of crushing. [Figure 7] 7(A) and (B) are graphs showing the results of test shots by different users. [Figure 8] FIG. 8 is a graph showing ideal values ​​for dynamic angle and attack angle. [Figure 9]9(A) to (C) are longitudinal cross-sectional views showing a manufacturing method of golf shaft 1, in which FIG. 9(A) shows a mandrel, FIG. 9(B) shows the state where prepreg has been wound around the mandrel of FIG. 9(A), and FIG. 9(C) shows the state where tape has been wound around the prepreg of FIG. 9(B). [Figure 10] FIG. 10 is a development view showing an example of the prepreg of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The objective of realizing a golf shaft that allows appropriate bending for any user is realized by providing a thin-walled portion in the middle of the golf shaft.

[0012] The golf shaft 1 comprises a hollow tubular body 3 having a tapered outer surface with the outer diameter gradually increasing between the tip end 5 and the base end 7. The tube body 3 comprises a thin-walled portion 11 and a thick-walled portion 13 due to the change in inner diameter between the tip end 5 and the base end 7. The thin-walled portion 11 has a relatively small thickness. The thick-walled portions 13 are located on both sides of the thin-walled portion 11 in the axial direction and have a relatively large thickness.

[0013] The thin portion 11 may be provided circumferentially or partially in the circumferential direction.

[0014] It is preferable that the thin-walled portion 11 has an inner diameter larger than a 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 .

[0015] The length of the tube 3 can be set within a range of, for example, 838 mm to 1194 mm. The position of the thin-walled portion 11 can be changed depending on the user's head speed, swing habits, and the like, but it is preferable that when the length of the tube 3 is 838 mm, the thin-walled portion 11 is located within a range of 150 mm to 688 mm from the tip 3a of the tube 3, and when the length of the tube 3 is 1194 mm, the thin-walled portion 11 is located within a range of 150 mm to 1044 mm from the tip 3a of the tube 3.

[0016] The thickened portion 13 may have a smaller inside diameter than the base shape 15 .

[0017] The material of the tube body 3 of the golf shaft 1 can be any appropriate material, and may be carbon fiber reinforced plastic.

[0018] The manufacturing method of such a golf shaft 1 involves winding prepreg 21 around the outer surface 17a of a mandrel 17 while positioning the radial protrusions 19 on the outer surface 17a, and then curing the prepreg 21 to form a hollow tube 3 having a thin-walled portion 11.

[0019] The projections 19 are preferably integral with the mandrel 17, but may be separate from the mandrel 17.

[0020] The projections 19 are preferably provided circumferentially around the mandrel 17 in accordance with the thin-walled portion 11 of the tube 3 .

[0021] Furthermore, it is preferable that the projection 19 has an outer diameter larger than a basic shape 29 formed by a line segment connecting the outer diameter of the tip end 23 and the outer diameter of the base end 25 of the mandrel 17 according to the thin-walled portion 11 .

[0022] Depending on the thin-walled portion 11, the protrusion 19 is preferably positioned in a range of 150 mm to 688 mm from the tip 3a of the tube 3 when the length of the tube 3 is 838 mm, and in a range of 150 mm to 1044 mm from the tip 3a of the tube 3 when the length of the tube 3 is 1194 mm.

[0023] The projection 19 may have recesses 20 on either side in the axial direction, the recesses 20 having an outer diameter smaller than the basic shape 29 of the mandrel 17 .

[0024] Depending on the material of the golf shaft 1, the prepreg 21 may be a carbon fiber sheet impregnated with a resin. EXAMPLES

[0025] [Golf shaft structure] Fig. 1 is a schematic longitudinal sectional view of a golf shaft according to Example 1 of the present invention. Fig. 2 is a transverse sectional view taken along line II-II in Fig. 1. Note that the longitudinal section refers to a section taken along the axial direction of the golf shaft, and the transverse section refers to a section perpendicular to the axial direction.

[0026] 1 is a shaft made of fiber-reinforced plastic, particularly carbon-reinforced plastic, and includes a hollow tube 3. The material of the tube 3 is not particularly limited, and it can be made of other fiber-reinforced plastics, metal, or a composite material.

[0027] The cross-sectional shape of the tube 3 is circular. However, the cross-sectional shape of the tube 3 may be other shapes such as ellipse. The length of the tube 3 is 838 mm to 1194 mm. However, the golf shaft 1 can be set to be shorter than 838 mm or longer than 1194 mm, but is generally in the range of 838 mm to 1194 mm.

[0028] The tubular body 3 is composed of a distal end portion 5 , a proximal end portion 7 , and an intermediate portion 9 .

[0029] The tip portion 5 is the tip portion in the axial direction, and refers to a region within a predetermined range from the tip 3a of the tube body 3 in the axial direction. The tip portion 5 in this embodiment is the portion to which the head of a golf club is attached. This tip portion 5 has a tapered outer surface in which the outer diameter gradually increases slightly toward the base end 3b. However, the tip portion 5 may be formed in a straight shape with a constant outer diameter.

[0030] The base end 7 is the base end of the tubular body 3 in the axial direction, and refers to a region within a predetermined range from the base end 3b of the tubular body 3 in the axial direction. The base end 7 in this embodiment is the portion to which a golf club grip is attached. This base end 7 has a straight outer surface with a constant outer diameter. However, the outer surface of the base end 7 may be tapered so that the outer diameter gradually changes slightly toward the base end 3b.

[0031] The intermediate portion 9 is a portion located between the distal end portion 5 and the proximal end portion 7, and has a tapered outer surface in which the outer diameter gradually increases slightly toward the proximal end 3b. Therefore, the tubular body 3 has a tapered outer surface in which the outer diameter gradually increases between the distal end portion 5 and the proximal end portion 7.

[0032] The tube 3 has a thin-walled portion 11 and a thick-walled portion 13 .

[0033] The thin-walled portion 11 is a portion having a relatively small thickness. The thin-walled portion 11 is provided continuously in a circumferential manner with respect to the tube body 3. Note that it is also possible to provide a plurality of thin-walled portions 11 in a discontinuous circumferential manner. It is also possible to provide the thin-walled portions 11 in a non-circumferential manner, spaced apart from each other on both sides in the radial direction.

[0034] This thin-walled portion 11 has an inner diameter larger than that of a corresponding portion of the basic shape 15. As a result, the 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 defined by a line segment (straight line) connecting the outer surface of the intermediate portion 9 with the inner diameter of the tip portion 5 and the inner diameter of the base portion 7.

[0035] The inner diameter and the outer diameter of the distal end portion 5 may be those of any part of the distal end portion 5. The inner diameter and the outer diameter of the proximal end portion 7 may be those of any part of the proximal end portion 7. Preferably, the inner diameter and the outer diameter of the distal end portion 5 and the proximal end portion 7 are those of the boundary portion with the intermediate portion 9.

[0036] The thin-walled portion 11 of this embodiment has a tapered inner surface 11a in which the inner diameter gradually increases from both sides in the axial direction. As a result, the thin-walled portion 11 has a gradually decreasing thickness from both sides in the axial direction. The thinnest part of the thin-walled portion 11 has a thickness of, for example, 1.03 mm to 1.46 mm, which is 98% to 99% of the thickness of the basic shape 15 at the same location (corresponding location) in the axial direction.

[0037] When the length of the tube 3 is 838 mm to 1194 mm, the position of the thin-walled portion 11 is in the range of 150 mm to 1044 mm from the tip 3a of the tube 3. More preferably, the position of the thin-walled portion 11 is in the range of 12% to 88% of the total length of the tube 3. When the length of the tube 3 is 838 mm, the position of the thin-walled portion 11 is preferably in the range of 150 mm to 688 mm from the tip 3a of the tube 3. When the length of the tube 3 is 1194 mm, the position of the thin-walled portion 11 is preferably in the range of 150 mm to 1044 mm from the tip 3a of the tube 3.

[0038] In this embodiment, the thinnest part of the thin-walled portion 11 is located in a range of 455 mm from the tip 3a (39% from the tip 3a of the tube 3), and the entire thin-walled portion 11 is located in a range of 392 mm to 597 mm from the tip (33% to 52% of the total length of the tube 3).

[0039] The thick-walled portions 13 are located on both sides of the thin-walled portion 11 in the axial direction, and are portions having a relatively large thickness. Each thick-walled portion 13 is provided continuously in a circumferential manner with respect to the tube body 3. However, it is also possible to provide a plurality of thick-walled portions 13 in a circumferential manner that are discontinuous. It is also possible to provide the thick-walled portions 13 in a non-circumferential manner, spaced apart on both sides in the radial direction.

[0040] This thick-walled portion 13 has an inner diameter smaller than that of the corresponding portion of the basic shape 15 of the tube 3. As a result, the 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, and may be the same thickness as that of the corresponding portion of the basic shape 15.

[0041] The thick-walled portion 13 of this embodiment has a tapered inner surface 13a in which the inner diameter gradually decreases from both sides in the axial direction. As a result, the thickness of the thick-walled portion 13 gradually increases from both sides in the axial direction. The thickness of the thick-walled portion 13 at its thickest point is, for example, 1.06 mm to 1.56 mm, which is 101% to 105% of the thickness of the basic shape 15 at the same location (corresponding location) in the axial direction.

[0042] The thick-walled portion 13 may be located in any area axially adjacent to the thin-walled portion 11. In this embodiment, the thickest part of the thick-walled portion 13 is located in a range of 330 mm (28% from the tip 3a of the tube 3) and 740 mm (64% from the tip 3a of the tube 3) from the tip, and the entire thick-walled portion 13 is located in a range of 155 mm to 392 mm (13% to 33% of the total length of the tube 3) and 597 mm to 900 mm (52% to 77% of the total length of the tube 3) from the tip.

[0043] The number of thick portions 13 and thin portions 11 can be set arbitrarily. For example, it is possible to provide two or more thin portions 11 and three or more thick portions 13.

[0044] [Golf shaft action] Figures 3(A) and (B) are schematic diagrams showing the bending and recovery of golf shaft 1, with Figure 3(A) being an embodiment and Figure 3(B) being a comparative example. Figure 4 is a cross-sectional view showing the crushing of thin-walled portion 11. The comparative example in Figure 3(B) is the same as golf shaft 1 of Example 1, except that it does not have thin-walled portion 11 and thick-walled portion 13.

[0045] In the golf shaft 1 of this embodiment, the thin-walled portion 11 is easily crushed when the user swings. Crushing refers to crushing the tube body 3 radially inward in the cross section of the golf shaft 1, and in this embodiment, refers to deformation to flatten the cross section of the tube body 3 into an elliptical shape.

[0046] Specifically, in the golf shaft 1, bending and straightening occur during a swing as shown in Fig. 3(A). Bending is a gradual deformation in the backward direction in the swing direction toward the tip portion 5, and straightening is a gradual deformation in the forward direction in the swing direction toward the tip portion 5, which is the opposite of bending.

[0047] 1, 3(A) and 4, when the golf shaft 1 of this embodiment flexes, the thin-walled portion 11 bends first, collapsing due to the presence of the thick-walled portions 13 on both sides. At this time, the thin-walled portion 11 is thinner than the corresponding portion of the basic shape 15 and therefore more easily collapses, so it bends first while collapsing more reliably.

[0048] Furthermore, in the golf shaft 1, the thickness gradually increases from the thin portion 11 to the thick portion 13, which suppresses abrupt changes in thickness and prevents stress concentration, thereby suppressing breakage.

[0049] The return to normal occurs when the thin-walled portion 11 returns to a circular shape and then bends again while collapsing in the opposite direction. Even during this return to normal, the thin-walled portion 11 is easily collapsed 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 portions of the basic shape.

[0050] On the other hand, typical bending and rebound does not have a preceding bending as shown in Fig. 3(B), but is an overall bending and rebound of the golf shaft 1. Compared to this case, in this embodiment, the absolute values ​​of the bending amount and the rebound amount can be made smaller. Therefore, with the golf shaft 1 of this embodiment, bending and rebound can be reliably obtained and easily controlled.

[0051] In addition, in the golf shaft 1 of this embodiment, the absolute values ​​of the amount of bending and the amount of return bending are reduced, thereby preventing the dynamic loft D from becoming excessively large, and it is possible to obtain an appropriate dynamic loft D. The dynamic loft D is the loft actually imparted to the ball at the time of impact.

[0052] Furthermore, in the golf shaft 1 of this embodiment, the attack angle A becomes gentle due to bending and returning, so the spin angle S can be suppressed. The attack angle A is the angle of incidence to the ball, and the spin angle S is the angle formed by the attack angle A and the dynamic loft D. As a result, the amount of spin can be reduced.

[0053] Fig. 5 is a graph showing the degree of crushing of the golf shaft 1 of this embodiment, Fig. 6(A) is a schematic diagram showing a method for measuring the degree of crushing, and Fig. 6(B) is a graph showing the measurement results of the degree of crushing. The higher the degree of crushing, the easier it is to crush. The degree of crushing was calculated based on the amount of deflection and bending rigidity at the time of three-point bending of the golf shaft 1.

[0054] Here, the bending stiffness is calculated by bending the golf shaft 1 over a measurement span L as shown in FIG. 6(A) and measuring the load at this time. The measurement span L was set to 300 mm. When the amount of bending is changed, a difference in bending stiffness (bending stiffness difference) occurs compared to before the amount of bending was changed as shown in FIG. 6(B). This is because crushing occurs as shown in FIG. 4, and the larger the amount of bending, the greater the impact. This bending stiffness difference is defined as the crushing degree.

[0055] As shown in FIG. 5, in the golf shaft 1 of this embodiment, it is understood that the degree of crushing is greater in the thin-walled portion 11 than on both sides in the axial direction.

[0056] 7A and 7B are graphs showing the results of test shots by different users. User A had a head speed of 43.5 m / s, and User B had a head speed of 39.9 m / s.

[0057] 7(A) and (B) show error ellipses based on plots of the results of test hits of the golf shaft 1 of the embodiment and the golf shaft of the comparative example. The comparative example is the same as the golf shaft 1 of the embodiment 1 except that it does not have the thin portion 11 and the thick portion 13.

[0058] As shown in FIGS. 7(A) and (B), for all users, the error ellipse is closer to the ideal values ​​of the dynamic loft D and the attack angle A when the golf shaft 1 of the embodiment is used for the test hit.

[0059] Figure 8 is a graph showing ideal values ​​for dynamic loft D and attack angle A. As shown in Figure 8, the ideal values ​​are for optimizing the launch angle and spin rate to increase the flight distance, and differ for each head speed.

[0060] Although the ideal values ​​differ for each head speed as shown in FIG. 8, the golf shaft 1 of the embodiment is able to bring the dynamic loft D and attack angle A closer to the ideal values ​​for both users A and B who have different head speeds.

[0061] Thus, the golf shaft 1 of this embodiment comprises a hollow tubular body 3 having a tapered outer surface in which the outer diameter gradually increases between the tip end 5 and the base end 7. Between the tip end 5 and the base end 7, the tubular body 3 comprises a thin-walled portion 11 having a relatively small thickness due to a change in the inside diameter, and thick-walled portions 13 located on both sides of the thin-walled portion 11 in the axial direction and having a relatively large thickness.

[0062] For this reason, in the golf shaft 1, bending and straightening occur in the thin-walled portion 11 before the tubular body 3, allowing any user to obtain an appropriate bending motion. Also, in the golf shaft 1, the absolute values ​​of the bending and straightening motion can be made small, making it easy to control the bending and straightening motion while reliably obtaining the bending and straightening motion.

[0063] Since the thin-walled portion 11 is provided in a circumferential shape, it can be crushed smoothly.

[0064] The thin-walled portion 11 has an inner diameter larger than the corresponding portion of the basic shape 15 formed by the line segments connecting the inner diameter and the outer diameter of the tip end portion 5 and the inner diameter and the outer diameter of the base end portion 7. Therefore, the thin-walled portion 11 of the golf shaft 1 can be compressed reliably, and appropriate bending can be obtained regardless of the user.

[0065] Furthermore, when the length of the tube 3 is 838 mm to 1194 mm, the thin-walled portion 11 is located within a length range of 150 mm to 1044 mm from the tip 3a of the tube 3, so that appropriate bending can be obtained regardless of the user.

[0066] [Manufacturing method of golf shafts] 9(A) to (C) are longitudinal cross-sectional views showing a manufacturing method of golf shaft 1, in which FIG. 9(A) shows a mandrel, FIG. 9(B) shows the state where prepreg has been wound around the mandrel of FIG. 9(A), and FIG. 9(C) shows the state where tape has been wound around the prepreg of FIG. 9(B).

[0067] In the manufacturing method of the golf shaft 1 of this embodiment, the prepreg 21 is wound around the outer surface 17a of the mandrel 17 while the radial projections 19 are positioned on the outer surface 17a as shown in FIGS. 9(A) and 9(B).

[0068] The mandrel 17 is rod-shaped and has a surface with a gradually increasing outer diameter from the tip to the base end. The mandrel 17 of this embodiment has a tip portion 23, an intermediate portion 25, and a base end portion 27 corresponding to the golf shaft 1. The tip portion 23 has an outer surface with a constant outer diameter from the tip 17b. The intermediate portion 25 has a protrusion 19 and a recess 20. The base end portion 27 has an outer surface with an outer diameter that gradually increases toward the base end 17c.

[0069] In this embodiment, the projection 19 is integral with the mandrel 17, but may be formed separately. The projection 19 has a shape that fits into the thin-walled portion 11. Therefore, the projection 19 in this embodiment is provided in a circumferential shape, and the outer diameter gradually increases from both sides in the axial direction. This projection 19 has an outer diameter larger than the corresponding portion of the basic shape 29 of the mandrel 17. The basic shape 29 is formed of a line segment (straight line) connecting the outer diameter of the tip portion 23 and the outer diameter of the base portion 27. Furthermore, the projection 19 is located corresponding to a portion of the tube 3 whose length from the tip 3a is in the range of 150 mm to 1044 mm when the length of the tube 3 is 838 mm to 1194 mm.

[0070] When the length of the tube 3 is 838 mm, the projection 19 is located in a portion of the tube 3 whose length from the tip 3a is in the range of 150 mm to 688 mm. When the length of the tube 3 is 1194 mm, the projection 19 is located in a portion of the tube 3 whose length from the tip 3a is in the range of 150 mm to 1044 mm.

[0071] The recesses 20 are located on both axial sides of the projection 19, and are continuous with the projection 19 by an outer surface whose outer diameter gradually decreases in correspondence with the thick-walled portion 13. The recesses 20 have an outer diameter smaller than that of the corresponding portion of the basic shape 29 formed by the line segment connecting the outer diameter of the tip end 23 and the outer diameter of the base end 27 of the mandrel 17.

[0072] A plurality of prepregs 21 having a predetermined cut shape and dimensions are wound around the mandrel 17. This winding is performed so that the prepregs 21 fit along the outer surface of the mandrel 17 having the projections 19. FIG. 10 shows a development of the prepregs 21. In the example of FIG. 10, six prepregs 21 are used. The number of prepregs 21 is appropriately set depending on the characteristics of the golf shaft 1.

[0073] Each prepreg 21 is a fiber sheet impregnated with a resin. The resin is not particularly limited, but may be an epoxy resin, an unsaturated polyester resin, a phenol resin, or the like. The fiber sheet may be, for example, a sheet of inorganic fibers such as metal fibers, boron fibers, carbon fibers, glass fibers, and ceramic fibers, aramid fibers, or other high-strength synthetic fibers. Inorganic fibers are preferably used because they are lightweight and strong. Among them, carbon fibers are most suitable because they have excellent specific strength and specific rigidity. Therefore, in this embodiment, a carbon fiber sheet is used as the fiber sheet.

[0074] After wrapping the prepreg 21 around the mandrel 17, as shown in Figure 9(C), tape 31 is further wrapped around it to maintain the prepreg 21 wrapped around the mandrel 17. By heating in this state, the prepreg 21 is hardened to obtain a tubular semi-finished product. After removing the tape 31, the outer surface of the semi-finished product is polished to become the tubular body 3 of the golf shaft 1 shown in Figure 1.

[0075] As described above, the tube body 3 has a thin-walled portion 11 having a relatively small thickness between the tip end 5 and the base end 7 in the portion corresponding to the protrusion 19, and has thick-walled portions 13 having a relatively large thickness on both sides of this thin-walled portion 11 in the axial direction.

[0076] Therefore, it is possible to realize a golf shaft 1 that can provide an appropriate bending regardless of the user. [Explanation of symbols]

[0077] 1 Golf shaft 3. Body 5 Tip (tube body) 7 Base end (tube body) 9 Middle section (body) 11 Thin section 13 Thick wall part 15 Basic shape (body) 17 Mandrel 19 Protrusion 21 Prepreg 23 Tip (mandrel) 25 Middle section (mandrel) 27 Base end (mandrel) 29 Basic shape (mandrel)

Claims

1. a hollow tubular body having a tapered outer surface whose outer diameter gradually increases in an intermediate portion between a distal end and a proximal end, the pipe body has, in the intermediate portion, a thin-walled portion having a relatively small wall thickness due to a change in inner diameter, and thick-walled portions located on both sides of the thin-walled portion in the axial direction and having a relatively large wall thickness; the thin-walled portion has an inner diameter larger than a corresponding portion of the basic shape including a line segment connecting the inner diameter of the tip end portion and the inner diameter of the base end portion at a boundary portion with the intermediate portion; Golf shaft.

2. 2. The golf shaft of claim 1, The thin-walled portion is provided in a circumferential shape. Golf shaft.

3. 2. The golf shaft of claim 1, The length of the tube is 838 mm to 1194 mm, When the length of the tube is 838 mm, the thin-walled portion is located in a range of 150 mm to 688 mm from the tip of the tube, and when the length of the tube is 1194 mm, the thin-walled portion is located in a range of 150 mm to 1044 mm from the tip of the tube. Golf shaft.

4. 3. The golf shaft of claim 2, The thick-walled portion has an inner diameter smaller than that of a corresponding portion of the basic shape. Golf shaft.

5. The golf shaft according to any one of claims 1 to 4, The pipe body is made of carbon fiber reinforced plastic. Golf shaft.

6. A method for manufacturing a golf shaft according to claim 1, comprising: The prepreg is wound around the surface of the mandrel while the radial projections are positioned on the surface of the mandrel. A hollow tube is formed by curing the prepreg. A method for manufacturing a golf shaft.

7. A method for manufacturing a golf shaft according to claim 6, comprising: The protrusion is integrally formed on the mandrel. A method for manufacturing a golf shaft.

8. 7. The method of manufacturing a golf shaft according to claim 6, The protrusion is provided circumferentially around the mandrel. A method for manufacturing a golf shaft.

9. 7. The method of manufacturing a golf shaft according to claim 6, the projection has an outer diameter larger than a corresponding portion of the basic shape including a line segment connecting the outer diameter of the tip end portion and the outer diameter of the base end portion of the mandrel; A method for manufacturing a golf shaft.

10. 7. The method of manufacturing a golf shaft according to claim 6, The length of the tube is 838 mm to 1194 mm, When the length of the tube is 838 mm, the protrusion is positioned in a range of 150 mm to 688 mm from the tip of the tube, and when the length of the tube is 1194 mm, the protrusion is positioned in a range of 150 mm to 1044 mm from the tip of the tube. A method for manufacturing a golf shaft.

11. 7. The method of manufacturing a golf shaft according to claim 6, a recessed portion having an outer diameter smaller than that of a corresponding portion of a basic shape including a line segment connecting the outer diameter of the tip end portion and the outer diameter of the base end portion of the mandrel, on both sides of the protrusion in the axial direction; A method for manufacturing a golf shaft.

12. A method for manufacturing a golf shaft according to any one of claims 6 to 11, The prepreg is a carbon fiber sheet impregnated with resin. A method for manufacturing a golf shaft.

Images