JP3627378B2 - Golf club shaft - Google Patents

Description

【００８５】
【発明の効果】
本発明のゴルフクラブ用シャフトは、上記能力を有することで、人が実際にボールを打つ場合に「ヒール打ち」しても破壊しにくく、軽量シャフトとしてゴルフクラブに使用できる。このようなシャフトを作製する構成として上記のような構成をとることで、軽量シャフトの曲げ強さを向上することができる。また、これにより、シャフトが軽量化することで、これまでよりシャフトの長尺化か可能になったり、大容量のヘッドをつけることが可能となり、飛距離アップなどができる。
【図面の簡単な説明】
【図１】本発明におけるゴルフクラブ用シャフトの補強層用プリプレグの巻き方の説明図である。
【符号の説明】
１：マンドレル
２：補強層用プリプレグ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lightweight and high-performance golf club shaft.
[0002]
[Prior art]
In recent years, shafts for golf clubs using fiber reinforced plastics are widely used because they are lightweight and have high performance such as high strength and high rigidity.
[0003]
Such a golf club shaft is expected to be further reduced in weight in the future. This weight reduction, strength and rigidity are contradictory problems, and it is desired to satisfy both weight reduction, high strength and high rigidity at the same time.
[0004]
The required characteristics of a golf club shaft are mainly bending strength, bending rigidity, torsional strength, torsional rigidity and shaft weight.
[0005]
However, when the weight of the golf club shaft is reduced, it has been difficult to satisfy all of the required performance. In particular, a lightweight golf club shaft has a problem in that it is easily broken when handled or hit (such as a case hitting the ground) because its bending strength and torsional strength are reduced.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a golf club shaft that solves the above-described problems and prevents breakage by suppressing a decrease in strength accompanying weight reduction in a lightweight golf club shaft, and exhibits sufficient performance. It is in.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the golf club shaft of the present invention isThe reinforcing fiber has a bias layer oriented in a direction of ± 15 ° to ± 80 ° with respect to the shaft axial direction, and an axial layer in which the reinforcing fiber is oriented in the shaft axial direction, and the axial layer is the bias Arranged outside the layerIn a golf club shaft made of fiber reinforced plastic,It further has a circumferential layer in which reinforcing fibers are arranged in the circumferential direction, and is the minimum strength required from a three-point bending test according to SG (Product Safety Association) standards.The bending strength P of the shaftOf the part from the shaft tip to 1100mmThe golf ball characterized in that the ratio (P / W) to the weight W per shaft length is in the range of the following formula (1), and the bending strength P of the shaft is in the range of the following formula (2). Club shaft.
[0008]
11 (N / g) ≦ P (N) / W (g) (1)
400 (N) ≦ P (N) (2)
[0009]
Moreover, a reinforcement layer can also be distribute | arranged to a part of shaft longitudinal direction as needed.
[0010]
Further, in the golf club shaft described above, the ratio T (Tb / Ta) of the thickness (Tb) of the circumferential layer to the thickness (Ta) of the axial layer is in the range of the following formula (3). Features.
[0011]
0.15 ≦ T ≦ 1.25 (3)
Furthermore, the golf club shaft of the present invention is a golf club shaft having a fiber reinforced plastic layer, an axial layer in which reinforcing fibers constituting the shaft are arranged in the shaft axial direction, and a circumferential layer arranged in the circumferential direction. The ratio T (Tb / Ta) of the circumferential layer thickness (Tb) to the axial layer thickness (Ta) is in the range of the following formula (3).
[0012]
0.15 ≦ T ≦ 1.25 (3)
The golf club shaft of the present invention is characterized in that the weight W per shaft is 55 g or less.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail together with preferred embodiments of the present invention.
[0014]
Examples of the reinforcing fiber used in the present invention include glass fiber, aramid fiber, carbon fiber, boron fiber, etc., but when a molded product is formed, carbon fiber is used because it exhibits particularly excellent mechanical properties. Is preferred. As the carbon fiber, polyacrylonitrile-based or pitch-based carbon fibers can be used. In addition, a reinforcing fiber can also be used individually or in combination of 2 or more types.
[0015]
In addition, as the matrix resin used in the present invention, an epoxy resin is usually used. As the epoxy resin, for example, bisphenol A type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, glycidylamine type epoxy resin, alicyclic epoxy resin, urethane modified epoxy resin, brominated A type epoxy resin, etc. are used. You can do it. These epoxy resins can be used singly or in combination of two or more, and can be used from liquid to solid. Usually, epoxy resins are often used with a curing agent added.
[0016]
The shaft for golf clubs of the present invention has a layer (fiber reinforced plastic layer) composed of the above reinforcing fibers and a matrix resin.
[0017]
In general, in a golf club, the required characteristics mainly include flight distance, hitting directionality, and feeling. Above all, increasing the flight distance is a major issue pursued by all golfers.
[0018]
As a method for increasing the flight distance, the golf club shaft may be made longer or lighter.
[0019]
With regard to the length of the golf club shaft, about 45 in (1143 mm) is becoming mainstream with drivers, and there are shafts longer than this. However, even if the length is further increased in the future, the longer it becomes, the more the weight will increase.
[0020]
On the other hand, in terms of weight reduction, the mainstream is about 60 to 80 g with a 45-inch shaft, and when the light-weight shaft is 55 g or less, there is a problem that the strength of the shaft decreases. It also affects properties such as stiffness.
[0021]
Thus, weight reduction is essential for a golf club shaft. However, breakage tends to occur due to a decrease in strength due to weight reduction. In order to prevent this destruction, there is a need for a golf club shaft that improves the strength of the shaft and also exhibits performance in terms of rigidity in order to maintain the performance as a shaft.
[0022]
Bending strength is a particularly important physical property in breaking golf club shafts. However, the bending strength decreases as the thickness is reduced due to weight reduction. That is, the golf club shaft can easily be broken. In addition to hitting the ball during actual golf, the golf club shaft may be damaged by placing an unreasonable load or heavy object when carrying in and out of the caddy bag. In some cases, the user leans on a golf club and puts weight on it.
[0023]
By the way, in general, when a person hits a ball, it is best to hit the ball at the sweet spot of the golf club head. However, in practice, the ball is often hit outside the sweet spot. In such a case, the directionality of the hit ball may be deteriorated, or the flight distance may be reduced. In particular, when the sweet spot is removed, the shaft is easily broken.
[0024]
In a lightweight shaft, when this sweet spot is removed and the ball is hit, it becomes easy to break. Therefore, the ratio (P / W) between the shaft bending strength P and the weight W per shaft length is 11 (N / g) It is required that there be more. Moreover, considering the safety of the shaft, it is important that the shaft bending strength P is 400 (N) or more. Here, the shaft bending strength P is the bending strength at the lowest point among the measured values of SG bending strength to be described later, and the weight W per length of the shaft is the shaft strength to be described later. It is the weight per length.
[0025]
Generally, the swing speed of a golf club is about 35 to 45 m / s, and the swing speed tends to increase in the future. When the ball is hit with a golf club, the shaft does not have to be broken at such a swing speed. Further, even if the ball is hit after the sweet spot is removed, the ball does not have to be broken. Furthermore, in consideration of a severe situation such as removing the sweet spot and hitting continuously, it is not necessary to destroy at a speed sufficiently higher than a general swing speed.
[0026]
Therefore, when the ratio (P / W) of the shaft bending strength P to the weight W per shaft length is 11 N / g or more, sufficient shaft strength is satisfied when the sweet spot is removed. It will be. Preferably, it is 12 N / g or more, more preferably 14 N / g or more.
[0027]
The present invention is particularly effective for a lightweight shaft as a golf club shaft. The lightweight golf club shaft has a weight W (generally per shaft length of 1100 mm) of 55 g or less, which will be described later, and preferably 45 g in order to efficiently use the effects of the present invention. Hereinafter, it is more preferably 40 g or less.
[0028]
A so-called flex is generally used as an index indicating the softness of a golf club shaft, and is indicated by S, R, etc. in commercial products. In the present invention, the shaft flex is measured using the measurement method described later. In general, if the flex is too large, the return of the head is delayed when swinging, the flight distance for flying the ball is reduced, the directionality of the ball is deteriorated, and the feeling is also deteriorated. Therefore, in the present invention, the shaft flex is preferably 100 mm or less, more preferably 90 or less. On the other hand, if the flex is too small, the shaft becomes stiff and force (or swing speed, etc.) is required. Therefore, in general, the shaft flex is preferably 70 mm or more. However, when it is generally better than Japanese, such as Westerners, it is used up to about 50 mm.
[0029]
Torque is generally used as an index indicating the torsional rigidity of the golf club shaft. Since the direction of the ball is better when the torque is smaller, in the present invention, the shaft torque in the measurement method described later is preferably 7 ° or less. The angle is more preferably 6 ° or less, and further preferably 5 ° or less.
[0030]
As means for producing such a golf club shaft, there are the following methods.
[0031]
A golf club shaft comprising a fiber reinforced plastic layer generally comprises an axial layer in which reinforcing fibers are arranged in the axial direction of the shaft, and a bias layer in which the reinforcing fibers are arranged at about 45 ° with respect to the axial direction of the shaft. Yes. It is known that the axial layer mainly controls the bending force of the shaft, and the bias layer mainly controls the torsional force of the shaft.In the present invention, it suffices that the bias layer is disposed in a direction of ± 15 ° to ± 80 ° with respect to the shaft axial direction, and the axial layer is preferably disposed outside the bias layer.
[0032]
That is, the bending strength of the golf club shaft is determined by the axial direction layer of the shaft. In order to improve the bending strength of the golf club shaft, the bending strength of the axial layer may be improved. However, it is difficult to say that the bending strength of the axial layer is sufficiently exerted in the bending strength of the shaft. Especially in the case of a lightweight shaft having a weight W per shaft length of 55 g or less, the capability of the axial layer is It is not demonstrated. This becomes more conspicuous as the shaft becomes lighter.
[0033]
When a bending force is applied to the shaft, the shaft deforms in the radial direction, so that the radial deformation failure occurs before the bending failure, and the shaft breaks before the bending failure. In addition, the deformation in the radial direction of the shaft causes a defect such as a non-fibrous fracture of the axial layer, and the axial layer does not exhibit a sufficient bending strength and breaks. As described above, the bending strength of the shaft is often caused by the radial deformation of the shaft.
[0034]
Therefore, in the present invention, in a golf club shaft having a weight W per shaft length of 55 g or less, an axial layer in which reinforcing fibers constituting the shaft are arranged in the shaft axial direction, and a circumferential direction arranged in the circumferential direction The ratio T (Tb / Ta) of the circumferential layer thickness (Tb) to the axial layer thickness (Ta) is
0.15 ≦ T ≦ 1.25
It is important to be in the range of
[0035]
The circumferential layer is preferably a layer in which reinforcing fibers are oriented perpendicular to the shaft axis direction, but may be a layer in which reinforcing fibers are oriented substantially perpendicular to the shaft axis direction. Specifically, the reinforcing fibers may be oriented about ± 85 to 90 ° with respect to the shaft axis direction.
[0036]
In order to make full use of the ability of the axial layer, it is important to have a circumferential layer. In order to suppress the radial deformation of the shaft to some extent, it is important to have a circumferential layer.
[0037]
By setting the ratio T (Tb / Ta) of the circumferential layer thickness (Tb) to the axial layer thickness (Ta) to be 0.15 or more and 1.25 or less, the radial deformation is suppressed, and the shaft The power of direction can be demonstrated. The ratio T (Tb / Ta) of the circumferential layer thickness (Tb) to the axial layer thickness (Ta) is preferably in the range of 0.15 to 1.00, more preferably 0.2 to 0.8. The range of is preferable.
[0038]
In general, the position where the circumferential layer is arranged to fully exhibit the ability of the axial layer is preferably on the outer side in the cross section of the shaft, and the outermost layer is most effective. However, when considering a golf club shaft, it is not preferable to use it for the outermost layer from the viewpoint of the moldability and aesthetics of the shaft. The position where the circumferential layer is arranged is arranged on the inner side of the center plane which is the thickness center of the shaft, in particular, on the inner side of the bias layer, whereby the torsional strength and torque of the shaft can be improved. The center plane that is the thickness center is a plane of 2.5 mm if the thickness is 5 mm in total, for example.
[0039]
Further, in order to efficiently express the bending strength of the shaft, it is preferable to arrange the circumferential layer in a place adjacent to the inner side of the axial layer that controls the bending strength of the shaft.
[0040]
For golf club shafts, light weight shafts of 55 g or less reduce the overall thickness and reduce the absolute amount of material. Therefore, the shaft should be well-balanced considering all the characteristics of the shaft such as bending and twisting. It becomes important. Therefore, if the amount of the axial layer that is the dominant element of the bending characteristics of the shaft is too large or too small, the balance of the shaft is deteriorated. It is preferable that the thickness (Tao) of the axial layer on the outer side of the thickness center largely resulting from the bending of the shaft is in the range of 0.03 mm or more and 0.4 mm or less. More preferably, they are 0.06 mm or more and 0.3 mm or less, More preferably, they are 0.08 mm or more and 0.25 mm or less.
[0041]
Sufficient strength is required for the reinforcing fibers used in the axial layer of the golf club shaft. For example, when carbon fibers are used as the reinforcing fibers, carbon fibers having high elastic modulus cannot be used because of the characteristics that the elastic modulus and strength are opposite to each other. Specifically, only fibers having a tensile modulus of carbon fiber of about 30 GPa or less were used. However, with a lightweight golf club shaft, not only the strength but also the flex is reduced.
[0042]
In the golf club shaft of the present invention, it is preferable to use a reinforcing fiber having a tensile elastic modulus of 35 GPa or more in the axial direction layer on the outer side from the center plane which is the thickness center of the shaft. By suppressing the deformation in the shaft radial direction as described above, a high elastic modulus reinforcing fiber can be used.
[0043]
The axial material used in the present invention is preferably a carbon fiber reinforced plastic that is a high bending strength material. Among them, the fiber cross-sectional shape of the reinforcing fiber is not only circular, but also polygonal, leaf-like, etc. Specific circular shape, for example, the minimum cross-sectional secondary profile P of the cross-sectional shape of the reinforcing fiber_min(= I_min/ A²) Having a modified cross-section reinforcing fiber of 0.085 or more is more preferable because it has an effect of improving strength.
[0044]
However, I_min: Minimum value of the secondary moment of inertia about the axis passing through the center of gravity of the single fiber cross section
A: Cross section of single fiber
A golf club using the shaft for a golf club of the present invention is preferably mounted on an inner hosel type head, and the effects of the present invention are more manifested.
[0045]
The fiber content of the fiber reinforced plastic layer in the golf club shaft of the present invention is preferably 30% by volume to 85% by volume, depending on the orientation angle of the reinforcing fiber used, considering its properties, particularly mechanical properties. % Is good.
[0046]
In order to manufacture the golf club shaft of the present invention, for example, if the golf club shaft is made of fiber reinforced plastic, a conventionally known mandrel having an outer diameter having the same taper as the shaft inner diameter is arranged in order from the innermost layer. In addition, a method of winding a prepreg in order to the outermost layer and winding a wrapping tape, FW (filament winding), a tape winding method, or the like can be used.
[0047]
The measuring method of each characteristic value in the present invention is as follows. Note that this measurement method is also used in the examples.
[0048]
(1) Shaft bending strength P
As the bending strength of the shaft, a value obtained from the three-point bending test method shown in the SG (Product Safety Association) standard is used. SG3 point bending strength is measured at 4 points (T, A, B, C) of the shaft. The shaft bending strength P of the golf club shaft shown in the present invention is the lowest bending strength among the four measuring portions.
[0049]
However, in the SG 3-point bending test, the A, B, and C portions of the four measurement points are the same test method, but the T portion has a span length of the other three points of the A, B, and C portions. Since it is half, the bending strength of the T part is halved.
[0050]
(2) Weight W per shaft length
Since the weight W per shaft length varies, the weight per 1100 mm is used in consideration of the driver. When the shaft length was 1100 mm or less, the weight proportional to the length of 1100 mm was used, and for the shaft of 1100 mm or more, the weight of the portion from the shaft tip to 1100 mm was used.
[0051]
(3) Shaft torque
In measuring the torque of the shaft in the present invention, 1016 mm from the tip of the shaft is set as a span, the hand of the shaft is fixed therefrom, and a twisting force of 138.5 kgf-mm is applied to a position 25.4 mm from the tip of the shaft. Measure the rotation angle. This rotation angle was defined as the shaft torque.
[0052]
(4) Shaft flex
In the measurement of the shaft flex in the present invention, the positions of 925 mm and 1065 mm from the shaft tip are supported, and the position of 200 mm moves from the shaft tip when a load of 2.7 kgf is applied to the position of 175 mm from the shaft tip. Measure the measured length (deflection amount). This amount of deflection was used as the shaft flex.
[0053]
(5) Golf club destructive test
In the present invention, the test using an air cannon was used as the golf club actual hitting test method. The test with an air cannon is a generally well-known method. A grip of a golf club is grasped, a ball is launched at an arbitrary initial speed from a position of about 2 m, and is applied to the head of the golf club.
[0054]
In the present invention, the ball hits the intersection of the head top score line and the shaft axis, that is, a so-called “heel strike” situation, the initial velocity of the ball is increased from 30 m / s, and the shaft breaks. The speed was measured.
[0055]
In general, the swing speed of a golf club is about 35 to 45 m / s, and it was determined that the golf club would not be broken at a speed that is at least 10% faster than this.
[0056]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples.
[0057]
First, the following prepreg was manufactured.
[0058]
Prepreg A: One-way prepreg obtained by impregnating PAN-based carbon fiber A (average single fiber diameter: 5 μm, tensile strength: 5490 MPa, tensile elastic modulus: 295 GPa) in parallel and in sheet form with an epoxy resin Prepared. The thickness was 113 μm and the matrix resin content was 33% by weight.
[0059]
Pre-preg B: One-way prepreg obtained by impregnating PAN-based carbon fiber B (average single fiber diameter: 5 μm, tensile strength: 4410 MPa, tensile elastic modulus: 375 GPa) in parallel and in a sheet form with an epoxy resin Prepared. The thickness was 127 μm and the matrix resin content was 33% by weight.
[0060]
Prepreg C: One-way prepreg formed by impregnating epoxy resin into PAN-based carbon fibers B (average single fiber diameter: 5 μm, tensile strength: 4410 MPa, tensile elastic modulus: 375 GPa) arranged in parallel and in sheet form Prepared. The thickness was 112 μm and the matrix resin content was 33% by weight.
[0061]
Prepreg D: A unidirectional prepreg formed by impregnating epoxy resin with PAN-based carbon fibers D (average single fiber diameter: 5 μm, tensile strength: 4020 MPa, tensile elastic modulus: 295 GPa) in parallel and in a sheet form Prepared. The thickness was 14 μm and the matrix resin content was 50% by weight.
[0062]
Pre-preg E: One-way prepreg obtained by impregnating PAN-based carbon fibers D (average single fiber diameter: 5 μm, tensile strength: 4020 MPa, tensile elastic modulus: 375 GPa) in parallel and in sheet form with an epoxy resin Prepared. The thickness was 47 μm and the matrix resin content was 58% by weight.
[0063]
FIG. 1 is an explanatory view of how to wind the reinforcing layer prepreg of the golf club shaft in the present invention. In the embodiment, when the reinforcing prepreg 2 is wound around the mandrel 1, the rough shape of the reinforcing layer is shown. And shows the position of wrapping around the mandrel.
[0064]
Example 1
As shown in FIG. 1, a prepreg A having 4 mm of prepreg A as a reinforcing layer on the inner tip side / 300 mm from the tip is applied to a stainless steel mandrel having a tip outer diameter of 4 mm, a taper ratio of 7.5 / 1000 mm, and a length of 1300 mm. Wrap around the prepreg E so that the reinforcing fiber is in the mandrel circumferential direction, and wind the prepreg B around the outer side so that the reinforcing fiber is approximately ± 45 ° with respect to the mandrel axial direction. The prepreg A was wound around the prepreg A so that the reinforcing fiber was in the mandrel axial direction. Thereafter, a wrapping tape, which is a well-known method, was wound and heated and cured in a curing furnace, and then the wrapping tape was removed, the surface was polished, and cut to 1100 mm to obtain a golf club shaft.
[0065]
The shaft bending strength of this golf club shaft was measured and found to be 600N. The weight of the shaft was 43 g, and the bending strength per unit shaft tip weight was 14.0 N / g. The shaft torque was measured and found to be 5.5 °. The shaft flex was measured and found to be 85 mm.
[0066]
On the other hand, a head and a grip were attached to the shaft manufactured in the same manner, and a golf club was obtained. When this golf club was destructively tested with an air cannon, the ball speed was
It destroyed at 59 m / s.
[0067]
Example 2
As in Example 1, the prepreg A is used as a reinforcing layer on the same mandrel as shown in FIG. 1, and the prepreg B is then wound around the inside four times so that the reinforcing fiber is approximately ± 45 ° with respect to the mandrel axial direction. The prepreg E was wound twice around the outer side so that the reinforcing fiber was in the mandrel circumferential direction, and the prepreg A was wound around the outer side so that the reinforcing fiber was in the mandrel axial direction. Thereafter, a wrapping tape, which is a well-known method, was wound and heated and cured in a curing furnace, and then the wrapping tape was removed, the surface was polished, and cut to 1100 mm to obtain a golf club shaft.
[0068]
The shaft bending strength of this golf club shaft was measured and found to be 620N. The weight of the shaft was 43 g, and the bending strength per unit shaft tip weight was 14.4 N / g. The shaft torque was measured and found to be 5.8 °. The shaft flex was measured and found to be 84 mm.
[0069]
On the other hand, a head and a grip were attached to the shaft manufactured in the same manner, and a golf club was obtained. When this golf club was subjected to a destructive test using an air cannon, the ball was broken at a speed of 60 m / s.
[0070]
Comparative Example 1
As in Example 1, prepreg A is used as a reinforcing layer around the same mandrel, as shown in FIG. 1, and is wound four times inside, and then the prepreg E is wound twice so that the reinforcing fibers are in the mandrel axial direction. The prepreg B was wound around the prepreg B so that the reinforcing fiber was approximately ± 45 ° with respect to the mandrel axial direction, and the prepreg A was wound around the outer side so that the reinforcing fiber was in the mandrel axial direction. Thereafter, a wrapping tape, which is a well-known method, was wound and heated and cured in a curing furnace, and then the wrapping tape was removed, the surface was polished, and cut to 1100 mm to obtain a golf club shaft.
[0071]
It was 420N when the shaft bending strength of this golf club shaft was measured. The weight of the shaft was 43 g, and the bending strength per unit shaft tip weight was 9.8 N / g. The shaft torque was measured and found to be 5.5 °. The shaft flex was measured and found to be 78 mm.
[0072]
On the other hand, a head and a grip were attached to the shaft manufactured in the same manner, and a golf club was obtained. When this golf club was subjected to a destructive test using an air cannon, the ball was broken at a speed of 45 m / s.
[0073]
Comparative Example 2
As in Example 1, the prepreg A is used as a reinforcing layer around the same mandrel as shown in FIG. 1, and the prepreg D is then wound twice so that the reinforcing fibers are in the mandrel circumferential direction. The prepreg B was wound around the prepreg B so that the reinforcing fiber was approximately ± 45 ° with respect to the mandrel axial direction, and the prepreg A was wound around the outer side so that the reinforcing fiber was in the mandrel axial direction. Thereafter, a wrapping tape, which is a well-known method, was wound and heated and cured in a curing furnace, and then the wrapping tape was removed, the surface was polished, and cut to 1100 mm to obtain a golf club shaft.
[0074]
The shaft bending strength of this golf club shaft was measured and found to be 450 N. Further, the weight of this shaft was 42 g, and the bending strength per unit shaft tip weight was 10.7 N / g. The shaft torque was measured and found to be 5.7 °. The shaft flex was measured and found to be 82 mm.
[0075]
On the other hand, a head and a grip were attached to the shaft manufactured in the same manner, and a golf club was obtained. When this golf club was subjected to a destructive test using an air cannon, the ball was broken at a speed of 48 m / s.
[0076]
Example 3
As in Example 1, the prepreg A is used as a reinforcing layer around the same mandrel, as shown in FIG. 1, and is wound four times inside, and then the prepreg E is wound seven times so that the reinforcing fibers are in the mandrel circumferential direction. The prepreg B was wound around the prepreg B so that the reinforcing fiber was approximately ± 45 ° with respect to the mandrel axial direction, and the prepreg A was wound around the outer side so that the reinforcing fiber was in the mandrel axial direction. Thereafter, a wrapping tape, which is a well-known method, was wound and heated and cured in a curing furnace, and then the wrapping tape was removed, the surface was polished, and cut to 1100 mm to obtain a golf club shaft.
[0077]
The shaft bending strength of this golf club shaft was measured and found to be 650N. Further, the weight of this shaft was 57 g, and the bending strength per unit shaft tip weight was 11.4 N / g. The shaft torque was measured and found to be 5.2 °. The shaft flex was measured and found to be 102 mm. On the other hand, a head and a grip were attached to the shaft manufactured in the same manner, and a golf club was obtained. When this golf club was subjected to a destructive test using an air cannon, the ball was broken at a speed of 61 m / s.
[0078]
Example 4
In the same manner as in Example 1, the prepreg C is reinforced around the same mandrel as shown in FIG. 1, and then the prepreg E is wound four times inside, and then the prepreg E is wound twice so that the reinforcing fiber is in the mandrel circumferential direction. The prepreg B was wound around the prepreg B so that the reinforcing fiber was approximately ± 45 ° with respect to the mandrel axial direction, and the prepreg C was wound around the outer side so that the reinforcing fiber was in the mandrel axial direction. Thereafter, a wrapping tape, which is a well-known method, was wound and heated and cured in a curing furnace, and then the wrapping tape was removed, the surface was polished, and cut to 1100 mm to obtain a golf club shaft.
[0079]
The shaft bending strength of this golf club shaft was measured and found to be 500N. The weight of the shaft was 43 g, and the bending strength per unit shaft tip weight was 11.7 N / g. The shaft torque was measured and found to be 5.5 °. The shaft flex was measured and found to be 76 mm.
[0080]
On the other hand, a head and a grip were attached to the shaft manufactured in the same manner, and a golf club was obtained. When this golf club was subjected to a destructive test using an air cannon, the ball was broken at a speed of 54 m / s.
[0081]
Comparative Example 3
As in Example 1, the prepreg C is reinforced with the prepreg C as a reinforcing layer on the same mandrel as shown in FIG. 1, and then the prepreg E is wound twice so that the reinforcing fiber is in the mandrel axial direction. The prepreg B was wound around the prepreg B so that the reinforcing fiber was approximately ± 45 ° with respect to the mandrel axial direction, and the prepreg C was wound around the outer side so that the reinforcing fiber was in the mandrel axial direction. Thereafter, a wrapping tape, which is a well-known method, was wound and heated and cured in a curing furnace, and then the wrapping tape was removed, the surface was polished, and cut to 1100 mm to obtain a golf club shaft.
[0082]
The shaft bending strength of this golf club shaft was measured and found to be 350N. Further, the weight of this shaft was 43 g, and the bending strength per unit shaft tip weight was 8.1 N / g. The shaft torque was measured and found to be 5.5 °. The shaft flex was measured and found to be 68 mm.
[0083]
On the other hand, a head and a grip were attached to the shaft manufactured in the same manner, and a golf club was obtained. When this golf club was subjected to a destructive test using an air cannon, it was broken at a velocity of 41 m / s.
[0084]
[Table 1]

[0085]
【The invention's effect】
Since the golf club shaft of the present invention has the above-mentioned ability, even when a person actually hits the ball, the golf club shaft is not easily broken and can be used as a lightweight shaft for a golf club. By taking the above-described configuration as a configuration for producing such a shaft, the bending strength of the lightweight shaft can be improved. In addition, this reduces the weight of the shaft, making it possible to increase the length of the shaft or to attach a large-capacity head, thereby increasing the flight distance.
[Brief description of the drawings]
FIG. 1 is an explanatory view of how to wind a reinforcing layer prepreg of a golf club shaft according to the present invention.
[Explanation of symbols]
1: Mandrel
2: Prepreg for reinforcing layer

Claims (6)

The reinforcing fiber has a bias layer oriented in a direction of ± 15 ° to ± 80 ° with respect to the shaft axial direction, and an axial layer in which the reinforcing fiber is oriented in the shaft axial direction, and the axial layer is the bias The golf club shaft made of fiber reinforced plastic arranged on the outer side of the layer further has a circumferential layer in which reinforcing fibers are arranged in the circumferential direction, and is the minimum required from a three-point bending test according to SG (Product Safety Association) standard The ratio (P / W) between the bending strength P of the shaft, which is the strength, and the weight W per shaft length of the portion from the shaft tip to 1100 mm is in the range of the following formula (1), and the bending of the shaft A golf club shaft having a strength P in the range of the following formula (2).
11 (N / g) ≦ P (N) / W (g) (1)
400 (N) ≦ P (N) (2) 2. The golf according to claim 1 , wherein a ratio T (Tb / Ta) of the thickness (Tb) of the circumferential layer to the thickness (Ta) of the axial layer is in the range of the following expression (3). Club shaft.
0.15 ≦ T ≦ 1.25 (3) 3. The golf club shaft according to claim 1, wherein a weight W per length of the shaft from the tip of the shaft to 1100 mm is 55 g or less. 4. The shaft torque , which is a rotation angle when a torsional force of 138.5 kgf-mm is applied to a position 25.4 mm from the shaft tip with a span of 1016 mm from the shaft tip, is 7 ° or less. Item 4. The golf club shaft according to any one of Items 1 to 3 . The shaft flex , which is supported by the 925mm and 1065mm locations from the shaft tip, and moved 200mm from the shaft tip when a load of 2.7kgf is applied to the position 175mm from the shaft tip, is less than 100mm Golf club shaft according to any one of claims 1 to 4, characterized in that. 6. The reinforcing fiber constituting the golf club shaft includes PAN-based carbon fiber, and the amount of the PAN-based carbon fiber is 75% by weight or more of the total amount of reinforcing fiber. The shaft for golf clubs described in 1.

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