Golf club shaft

Abstract

The present invention addresses the problem of providing a golf club shaft that is lightweight but can exhibit good durability and also can suppress flex deterioration. This golf club shaft has a mass in the range from 30-60 g. Also, this shaft exhibits a flex in the range from 8-20 kg. Furthermore, when a head is attached to the distal end of the shaft that weighs less than 45 g and a golf ball is hit with the head at a head speed of 38 m / s, the endurance count of the shaft is 1200 times or more, and when a head is attached to the distal end of that shaft that weighs 45 g or more and a golf ball is hit with the head at a head speed of 44 m / s, the endurance count of the shaft is 1800 times or more.

Description

Golf club shaft

[0001] The present invention relates to a shaft for a golf club.

[0002] In recent years, golf club shafts have become lighter in order to improve the distance a ball can travel, and various shaft weight reduction techniques have been proposed in the past (see, for example, Japanese Patent Application Laid-Open Nos. 2009-229444 and 2012-130533).

[0003] JP 2009-229444 A JP 2012-130533 A

[0004] However, when a shaft is made lighter, not only does the durability of the shaft decrease, but the flex also decreases (i.e., the shaft becomes more flexible). The object of the present invention is to provide a golf club shaft that is lightweight but exhibits good durability and can suppress the decrease in flex.

[0005] A golf club shaft according to a first aspect of the present invention has a mass ranging from 30 g to 60 g. This shaft also exhibits a flex ranging from 8 kg to 20 kg. Furthermore, when a head is attached to the tip end of a shaft weighing less than 45 g and a golf ball is hit with the head at a head speed of 38 m / s, the shaft has a durability of 1,200 or more strokes, and when a head is attached to the tip end of a shaft weighing 45 g or more and a golf ball is hit with the head at a head speed of 44 m / s, the shaft has a durability of 1,800 or more strokes. The length of this shaft is preferably 1,170 ± 2 mm.

[0006] Therefore, although the shaft is lightweight, it is possible to exhibit good durability and to suppress a decrease in flex.

[0007] A golf club shaft according to a second aspect of the present invention is the golf club shaft according to the first aspect, and is formed by laminating a first prepreg, a second prepreg, and an outermost prepreg. The first prepreg has a thickness of 20 g / m ２ More than 100g / m ２The first prepreg includes first fibers within the following range. The first prepreg is wound continuously for two or more turns so that the orientation angle of the first fibers is within the range of 80° to 100°. The second prepreg includes second fibers. The second fibers have a fiber elastic modulus within the range of 350 GPa to 800 GPa. The second prepreg is wound adjacent to the first prepreg on the outside of the first prepreg so that the orientation angle of the second fibers is within the range of ±30° to ±40°. The outermost prepreg includes third fibers. The third fibers have a fiber break elongation within the range of 1.5% to 3.0%. The outermost prepreg is wound around the second prepreg on the outside of the second prepreg so that the orientation angle of the third fibers is within the range of -5° to 5°. Note that another prepreg may be provided between the second prepreg and the outermost prepreg depending on the purpose. Here, the orientation angle is determined based on the axis of the shaft, that is, the axis of the shaft is set to 0°.

[0008] Therefore, this shaft can be manufactured using conventional prepreg lamination techniques.

[0009] A golf club shaft according to a third aspect of the present invention is the golf club shaft according to the second aspect, further comprising a decorative layer. The decorative layer is made of at least one of paint, print, fabric, and a unidirectional fiber sheet. In such a case, the decorative layer is the outermost layer of the golf club shaft in terms of layout, but is a completely separate layer in terms of function. Furthermore, the decorative layer preferably uses a prepreg made of fibers with a fiber breaking elongation in the range of 1.5% to 3.0%.

[0010] This allows the shaft to have a distinctive design.

[0011] The golf club shaft according to the embodiment of the present invention is a so-called lightweight shaft, and when the length is 1170±2 mm, it has a mass in the range of 30 g to 60 g. This mass is preferably in the range of 30 g to 55 g, more preferably in the range of 30 g to 50 g, even more preferably in the range of 30 g to 45 g, and particularly preferably in the range of 30 g to 40 g. However, some golf players may prefer a higher mass.

[0012] This shaft also exhibits a flex within the range of 8 kg to 20 kg. Note that the preferred range of this flex varies depending on the mass range. When the mass of the shaft is within the range of 30 g to 38 g, the flex is preferably within the range of 8 kg to 10.4 kg. When the mass of the shaft is within the range of more than 38 g to 43 g, the flex is preferably within the range of 10.5 kg to 11.9 kg. When the mass of the shaft is within the range of more than 43 g to 49 g, the flex is preferably within the range of 12 kg to 15.4 kg. When the mass of the shaft is within the range of more than 49 g to 60 g, the flex is preferably within the range of 15.5 kg to 20 kg.

[0013] This shaft also exhibits symmetrical torque characteristics that comply with Golf Association regulations.

[0014] Furthermore, when a head is attached to the tip of a shaft weighing less than 45 g and a golf ball is hit with the head at a head speed of 38 m / s, the shaft's durability is 1,200 or more strokes. When a head is attached to the tip of a shaft weighing 45 g or more and a golf ball is hit with the head at a head speed of 44 m / s, the shaft's durability is 1,800 or more strokes. This durability is preferably 1,800 or more strokes when the shaft's mass is less than 45 g. In the embodiments of the present invention, the "shaft durability" refers to the number of strokes after a golf ball is hit with a golf club equipped with the shaft, at which no damage such as microcracks is observed on the shaft surface when the shaft surface is observed under an optical microscope. The durability is measured by test shots using a highly repeatable robot, such as the Golf Shot Robo 3DX manufactured by Miyamae Co., Ltd. The head used in the measurement is a Taylormade M1 460 or an equivalent (e.g., a head with a titanium face and weighing approximately 200 g). It should be noted that in this durability test, the golf ball was heel-hit, so the influence of the head face material, etc. was relatively small. The golf balls used were Titleist Pro V1 manufactured by Acushnet Golf Clubs or equivalent (commercially available balls weighing approximately 45.93 g that conform to the Rules of Golf and have the same hardness as the Titleist Pro V1).

[0015] The golf club shaft according to the embodiment of the present invention is formed by laminating a first prepreg, a second prepreg, and an outermost prepreg. Note that prepregs with a resin content of 20% by mass or less are not used in manufacturing the shaft according to the embodiment of the present invention. Each of the prepregs described above will be described in detail below. Note that the fiber orientation angle is specified in the description of each prepreg, but this orientation angle is determined with reference to the axis of the shaft. In other words, the axis of the shaft is set to 0°.

[0016] The first prepreg is 20 g / m ２ More than 100g / m ２ The first prepreg contains the first fibers in the following range. ２90g / m or more ２ It is preferable that the first fibers are contained in the following range: 20 g / m ２ 80g / m or more ２ It is more preferable that the first fibers are contained in the range of 20 g / m ２ 70g / m or more ２ It is more preferable that the first fibers are contained in the range of 20 g / m ２ 60g / m or more ２ It is more preferable that the first fibers are contained in the range of 20 g / m ２ 50g / m or more ２ It is more preferable that the first fibers are contained in the range of 20 g / m ２ 40g / m or more ２ It is particularly preferable that the first fibers are contained within the following range. The first fibers are preferably carbon fibers. The first prepreg may also contain a resin such as an epoxy resin, but the resin may be a resin that has been used previously. The first prepreg is wound continuously for two or more turns so that the orientation angle of the first fibers is within the range of 80° to 100°. The orientation angle is preferably within the range of 85° to 95°. The first prepreg is preferably a unidirectional prepreg, i.e., a prepreg in which the first fibers are aligned in one direction.

[0017] The second prepreg includes second fibers. The second fibers are preferably carbon fibers. The second prepreg may also include a resin such as an epoxy resin, but the resin may be a conventionally used resin. The second fibers have a fiber modulus of elasticity in the range of 350 GPa to 800 GPa. The fiber modulus depends on the desired shaft performance, but is preferably in the range of 350 GPa to 800 GPa, more preferably 350 GPa to 700 GPa, even more preferably 350 GPa to 600 GPa, and particularly preferably 350 GPa to 500 GPa. The second fibers also have a fiber breaking elongation in the range of 0.7% to less than 1.5%, more preferably 0.8% to less than 1.5%, even more preferably 1.0% to less than 1.5%, and particularly preferably 1.2% to less than 1.5%. The second prepreg is wound adjacent to the first prepreg on the outside thereof so that the orientation angle of the second fibers is within a range of ±30° to ±40°. To suppress a decrease in flex, the orientation angle is preferably within a range of ±30° to ±35°. To suppress a decrease in torque, the orientation angle is preferably within a range of ±35° to ±40°. The second prepreg is preferably a unidirectional prepreg, i.e., a prepreg in which the second fibers are aligned in one direction.

[0018] The outermost prepreg includes a third fiber. The third fiber is preferably a carbon fiber, and more preferably a PAN-based carbon fiber. The outermost prepreg may also include a resin such as an epoxy resin, but the resin may be a conventionally used resin. The third fiber has a fiber break elongation of 1.5% to 3.0%. The fiber break elongation is preferably 1.8% to 3.0%, more preferably 2.0% to 3.0%, even more preferably 2.1% to 3.0%, even more preferably 2.2% to 3.0%, and particularly preferably 2.5% to 3.0%. The third fiber also has a fiber elastic modulus of 230 GPa to less than 350 GPa, more preferably 290 GPa to 350 GPa, and even more preferably 320 GPa to 350 GPa. The outermost prepreg is wound around the outside of the second prepreg so that the orientation angle of the third fibers is within a range of -5° to 5°. The outermost prepreg may be a UD prepreg (unidirectional prepreg, a prepreg in which carbon fibers are aligned in one direction) or a woven fabric prepreg. When the outermost prepreg is a woven fabric prepreg, the orientation angle of the fibers perpendicular to the third fibers is within a range of 85° to 95°.

[0019] In addition, in the shaft according to the embodiment of the present invention, the outermost prepreg may be given a decorative finish such as painting or wrapping film, or a decorative layer made of at least one of a woven fabric and a unidirectional fiber sheet may be formed on the outermost prepreg.

[0020] The above-described prepreg laminated structure makes it possible to allocate apparent stiffness in the longitudinal direction while maintaining good torque performance of the shaft, and in turn makes it possible to produce a shaft that is lightweight, has high initial stiffness, and exhibits good durability.

[0021] 1. Preparation of carbon shaft Carbon fiber exhibiting elasticity of 294 GPa was used at 25 g / m ２A first UD prepreg (unidirectional prepreg, a prepreg in which carbon fibers are aligned in one direction) containing the carbon fibers was wound continuously around a metal mandrel for two turns so that the orientation angle of the carbon fibers was 90°. The orientation angle here refers to the angle that the carbon fibers make with respect to the axis of the mandrel, and ultimately becomes the angle with respect to the axis of the shaft. Next, carbon fibers exhibiting an elasticity of 475 GPa and an elongation at break of 0.8% were wound at 75 g / m ２ Two second UD prepregs containing the carbon fiber were stacked so that the orientation angles of the carbon fibers were alternately +35° / −35°, and the stacked prepregs were wound twice around the upper side of the first UD prepreg. Next, 125 g / m of carbon fiber having an elasticity of 377 GPa and an elongation at break of 1.2% was added. ２ The third UD prepreg containing the carbon fiber was wound once around the upper side of the second UD prepreg so that the orientation angle of the carbon fiber was 0°, and then 100 g / m of carbon fiber exhibiting elasticity of 377 GPa and elongation at break of 1.2% was further wound on the third UD prepreg containing the carbon fiber. ２ The fourth UD prepreg containing 125 g / m2 of carbon fiber exhibiting an elasticity of 294 GPa and an elongation at break of 2.0% was wound around the prepreg once so that the orientation angle of the carbon fiber was 0°. ２ A fifth UD prepreg (corresponding to the "outermost prepreg" in claim 2) containing the above-mentioned carbon fibers was wound around the top of the fourth UD prepreg one turn at a time so that the orientation angle of the carbon fibers was 0°. Then, a carbon fiber fabric made of carbon fibers exhibiting an elasticity of 230 GPa was wound around the top of the fifth prepreg one turn as a decorative layer so that the orientation angle of the carbon fibers in the carbon fiber fabric was 0° / 90°, and the laminated prepreg was then vacuum-sealed with a bagging film. The laminated prepreg in this state was then cured in an autoclave to obtain the desired carbon shaft. The resin constituting each prepreg was the same type of epoxy resin cured at 130°C. The length of this carbon shaft was 1170 mm.

[0022] 2. Measurement of Physical Properties of Carbon Shaft (1) Mass Measurement The mass of the above-mentioned carbon shaft was measured using a weighing machine and was found to be 48.5 g.

[0023] (2) Flex Measurement The flex of the above-mentioned carbon shaft was measured using an Auditor Golf Shaft Profiler in accordance with golf standards, and the flex of the carbon shaft was found to be 15.3 kg.

[0024] (3) Torque Measurement The torque of the above-mentioned carbon shaft was measured using an Auditor Digital Shaft Torque Meter in accordance with golf standards, and the torque of the carbon shaft was found to be 6.7°.

[0025] (4) Durability Test A golf club was assembled by attaching a Taylormade M1 460 to the tip end of the above-mentioned carbon shaft, and the golf club was attached to a Golf Shot Robo 3DX manufactured by Miyamae Co., Ltd. The head was then hit with a Titleist Pro V1 golf ball manufactured by Acushnet Co., Ltd. at a head speed of 44 m / s by heel strike 1,800 times using the Golf Shot Robo 3DX. After that, the entire surface of the carbon shaft was observed with an optical microscope, and no defects including microcracks were confirmed.

[0026] The target carbon shaft was produced in accordance with the method described in "1. Production of carbon shaft" in Example 1, except that the fifth UD prepreg in Example 1 was replaced with a UD prepreg having carbon fibers exhibiting an elasticity of 324 GPa and an elongation at break of 2.0%, and no decorative layer was provided.

[0027] The various physical properties of the above-mentioned carbon shaft were measured according to the various measurement methods described in "2. Measurement of physical properties of carbon shaft" in Example 1, and the weight was 48.5 g, the flex was 16.9 kg, and the torque was 7.3°. Furthermore, when the entire surface of the shaft was observed under a microscope after hitting golf balls 1,800 times under the same conditions as those described in Example 1, no defects including microcracks were found on the entire surface of the shaft.

[0028] A target carbon shaft was produced in accordance with the method described in "1. Production of carbon shaft" in Example 1, except that the third UD prepreg and fourth UD prepreg in Example 1 were replaced with prepregs having carbon fibers exhibiting an elasticity of 294 GPa and an elongation at break of 2.0%.

[0029] The various physical properties of the above-mentioned carbon shaft were measured according to the various measurement methods described in "2. Measurement of physical properties of carbon shaft" in Example 1, and the weight was 47.6 g, the flex was 10.9 kg, and the torque was 6.8°. Furthermore, when the entire surface of the shaft was observed under a microscope after hitting golf balls 1,800 times under the same conditions as those described in Example 1, no defects including microcracks were found on the entire surface of the shaft.

[0030] The target carbon shaft was produced in accordance with the method described in "1. Production of carbon shaft" in Example 1, except that the decorative layer in Example 1 was replaced with a prepreg having a carbon fiber fabric made of carbon fibers exhibiting an elasticity of 294 GPa and an elongation at break of 2.0%.

[0031] The various physical properties of the carbon shaft were measured according to the various measurement methods described in "2. Measurement of physical properties of carbon shaft" in Example 1, and the weight was 48.8 g, the flex was 15.1 kg, and the torque was 6.8°. Furthermore, when the entire surface of the shaft was observed under a microscope after hitting golf balls 1,800 times under the same conditions as those described in Example 1, no defects including microcracks were found on the entire surface of the shaft.

[0032] The third UD prepreg in Example 1 was made of 75 g / m of carbon fiber exhibiting an elasticity of 377 GPa and a breaking elongation of 1.2%. ２ The fourth UD prepreg and the fifth UD prepreg were replaced with prepregs containing 75 g / m of carbon fiber exhibiting an elasticity of 294 GPa and an elongation at break of 2.0%. ２The target carbon shaft was produced in accordance with the method described in "1. Production of carbon shaft" in Example 1, except that the prepreg containing

[0033] The various physical properties of the carbon shaft were measured according to the various measurement methods described in "2. Measurement of Physical Properties of Carbon Shaft" in Example 1, and the weight was found to be 38.4 g, the flex to be 10.3 kg, and the torque to be 8.0°. A Taylormade M1 460 was attached to the tip end of the carbon shaft to assemble a golf club, and the golf club was then attached to a Golf Shot Robo 3DX manufactured by Miyamae Co., Ltd., and the head was used to hit a Titleist Pro V1 golf ball manufactured by Acushnet Golf Club 1,200 times at a head speed of 38 m / s by heel strikes. After that, the entire surface of the carbon shaft was observed under an optical microscope, and no defects including microcracks were found.

[0034] Carbon fiber exhibiting elasticity of 294 GPa at 25 g / m ２ The first UD prepreg containing 75 g / m2 of carbon fiber exhibiting an elasticity of 475 GPa and an elongation at break of 0.8% was wound around a metal mandrel twice in succession so that the orientation angle of the carbon fiber was 90°. ２ Two second UD prepregs containing the carbon fiber were stacked so that the orientation angles of the carbon fibers were alternately +35° / −35°, and the stacked prepregs were wound twice around the upper side of the first UD prepreg. Next, 150 g / m of carbon fiber having an elasticity of 294 GPa and an elongation at break of 2.0% was used. ２ The third UD prepreg containing the carbon fiber was wound once around the upper side of the second UD prepreg so that the orientation angle of the carbon fiber was 0°, and then 150 g / m of carbon fiber exhibiting an elasticity of 294 GPaGPa and an elongation at break of 2.0% was further wound on the third UD prepreg containing the carbon fiber. ２ The fourth UD prepreg containing 125 g / m2 of carbon fiber exhibiting an elasticity of 294 GPa and an elongation at break of 2.0% was wound around the prepreg once so that the orientation angle of the carbon fiber was 0°. ２A fifth UD prepreg (corresponding to the "outermost prepreg" in claim 2) containing the above-mentioned carbon fibers was wound around the top of the fourth UD prepreg one turn at a time so that the orientation angle of the carbon fibers was 0°. Then, a carbon fiber fabric made of carbon fibers exhibiting an elasticity of 294 GPa was wound around the top of the fifth prepreg one turn as a decorative layer so that the orientation angle of the carbon fibers in the carbon fiber fabric was 0° / 90°, and the laminated prepreg was then vacuum-sealed with a bagging film. The laminated prepreg in this state was then cured in an autoclave to obtain the desired carbon shaft. The resin constituting each prepreg was the same type of epoxy resin cured at 130°C. The length of this carbon shaft was 1170 mm.

[0035] The various physical properties of the carbon shaft were measured according to the various measurement methods described in "2. Measurement of Physical Properties of Carbon Shaft" in Example 1, and the weight was found to be 60.0 g, the flex to be 19.0 kg, and the torque to be 5.3°. A Taylormade M1 460 was attached to the tip end of the carbon shaft to assemble a golf club, and the golf club was then attached to a Golf Shot Robo 3DX manufactured by Miyamae Co., Ltd., and the head was used to hit a Titleist Pro V1 golf ball manufactured by Acushnet Golf Club 1,800 times at a head speed of 46 m / s by heel strikes. After that, the entire surface of the carbon shaft was observed under an optical microscope, and no defects including microcracks were confirmed.

[0036] (Comparative Example 1) The target carbon shaft was produced in accordance with the method described in "1. Production of carbon shaft" in Example 1, except that the winding of the first prepreg around the mandrel in Example 3 was changed to one turn, and after winding the second prepreg, the first prepreg was again wound one turn.

[0037] The various physical properties of the carbon shaft were measured according to the various measurement methods described in "2. Measurement of physical properties of carbon shaft" in Example 1, and the weight was 47.7 g, the flex was 11.1 kg, and the torque was 6.9°. Furthermore, when golf balls were continuously hit under the same conditions as those shown in Example 1, the shaft broke before hitting 1,800 balls.

[0038] Comparative Example 2 A target carbon shaft was produced in accordance with the method described in "1. Production of carbon shaft" in Example 1, except that the third UD prepreg, fourth UD prepreg, and fifth UD prepreg in Example 1 were replaced with UD prepregs having carbon fibers exhibiting an elasticity of 377 GPa and an elongation at break of 1.2%.

[0039] The various physical properties of the carbon shaft were measured according to the various measurement methods described in "2. Measurement of physical properties of carbon shaft" in Example 1, and the weight was 48.8 g, the flex was 15.7 kg, and the torque was 6.7°. Furthermore, when golf balls were continuously hit under the same conditions as those shown in Example 1, the shaft broke before hitting 1,800 balls.

[0040] The golf club shaft according to the present invention is lightweight, yet exhibits good durability and is able to suppress a decrease in flex, thereby realizing the user's dream of increasing the distance the ball can travel.

Claims

1. A golf club shaft having a mass within the range of 30g or more and 60g or less, exhibiting a flex within the range of 8kg or more and 20kg or less, and when the shaft weighs less than 45g, the shaft has a durability of 1,200 or more strokes when a head is attached to the tip side and a golf ball is hit with said head at a head speed of 38m / s, and when the shaft weighs 45g or more, the shaft has a durability of 1,800 or more strokes when a head is attached to the tip side and a golf ball is hit with said head at a head speed of 44m / s.

2. 20g / m ２ More than 100g / m ２ 2. The golf club shaft according to claim 1, wherein the shaft is formed by laminating together: a first prepreg including first fibers having a fiber elastic modulus within the following range and wound continuously for two or more turns so that an orientation angle of the first fibers is within the range of 80° or more and 100° or less; a second prepreg including second fibers having a fiber elastic modulus within the range of 350 GPa or more and 800 GPa or less and wound adjacent to the first prepreg on the outside of the first prepreg so that an orientation angle of the second fibers is within the range of ±30° or more and ±40° or less; and an outermost prepreg including third fibers having a fiber breaking elongation within the range of 1.5% or more and 3.0% or less and wound around the outside of the second prepreg so that an orientation angle of the third fibers is within the range of -5° or more and 5° or less.

3. The shaft of a golf club according to claim 2, further comprising a decorative layer made of at least one of a woven fabric and a unidirectional fiber sheet.