JPH09327536A - Shaft for lightweight golf club and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shaft which is reduced in weight to 35 to 50% of the weight of the conventional shafts while the characteristics of the shaft, such as bending rigidity, bending strength, torsional rigidity and torsional strength and the outside diameter thereof are maintained. SOLUTION: The shaft for golf clubs formed by laminating plural fiber reinforced composite materials has reinforcing layers in order of an angle layer, straight layer, angle layer and straight layer successively from the inner side over the entire length of the shaft. The angle layer on the outer side is 0.04 to 0.1mm thickness, the torsional strength thereof is >=120N.m. deg. and the weight thereof is 30 to 45g. The fiber METSUKE (unit) of the prepreg forming the angle layer on the outer side is 18 to 55g/m<2> and the thickness thereof is <=0.05mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a golf club shaft (hereinafter, simply referred to as a shaft), particularly bending rigidity,
While maintaining the conventional shaft characteristics such as bending strength, torsional rigidity, and torsional strength, and the outside diameter,
The present invention relates to a shaft lightened to 5 to 50% and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, as golf club shafts,
A shaft made of fiber reinforced plastics (hereinafter, referred to as FRP) obtained by winding a so-called unidirectional prepreg, in which reinforcing fibers are aligned and impregnated with resin, around a tapered core metal serving as a mold, and laminated and hardened, has a specific rigidity and a specific strength. It is widely used because of its height and freedom of design.

In many cases, a shaft made of FRP has a two-layer structure of an angle layer and a straight layer from the inside. Here, the angle layer is a layer formed by laminating prepregs in which reinforcing fibers are attached so as to be + θ and −θ in the longitudinal direction of the shaft (where θ = 35 to 55 °), and is a straight layer. Is a layer formed by laminating prepregs in which reinforcing fibers are oriented within ± 20 ° with respect to the longitudinal direction of the shaft.

In recent years, the weight of the shaft has been reduced for the purpose of improving the head speed, lengthening the shaft, and enlarging the sweet area accompanying the increase in the size of the head.

There is a problem in that the bending rigidity, bending strength, torsional rigidity and torsional strength of the shaft are correspondingly reduced by simply reducing the number of straight layers and angle layers constituting the shaft.

[0006]

The bending rigidity of the shaft,
As a method to reduce the weight while maintaining the torsional rigidity,
(1) A method in which the number of straight layers and / or angle layers is reduced and at the same time, the elastic modulus of the reinforcing fibers forming these layers is changed to reinforcing fibers having higher elasticity, (2) the shape of the shaft itself, mainly There is a method to increase the diameter and reduce the thickness.

However, in the method (1), since the reinforcing fiber having high elasticity generally has low strength, the bending rigidity and the torsional rigidity are comparable to those of the conventional shaft.
Bending strength and torsional strength are the same as those obtained by simply reducing the number of layers, or result in lowering. In the method (2), it is possible to increase the outer diameter near the grip to maintain bending rigidity. It is effective, but it has not been adopted because it has a difficulty in using the shaft.

Further, as a method for improving the torsional rigidity and torsional strength of a FRP shaft, there is disclosed in Japanese Utility Model Laid-Open No. 62-3387.
No. 2 discloses FR having an angle layer and a straight layer.
A method of further providing an angle layer on the outermost layer of the shaft made of P is disclosed, but in this method, the angle layer required for maintaining the torsional rigidity and the torsional strength of the FRP shaft is the same as that of the FRP shaft such as polished. It may be lost due to finish processing, a stable quality FRP shaft cannot be obtained, and it does not contribute to weight reduction of the FRP shaft.

[0009]

In view of the above, the inventors of the present invention have considered that the conventional shaft characteristics of 35, such as bending rigidity, bending strength, torsional rigidity, and torsional strength, and the outer diameter are maintained. The present invention has been accomplished by earnestly studying a shaft that has been reduced in weight to 50%.

[0010]

SUMMARY OF THE INVENTION The present invention is a golf club shaft comprising a plurality of fiber-reinforced composite material layers laminated, the first angle layer, the first straight layer, the first straight layer, and the first straight layer from the inside over the entire length of the shaft. The second angle layer has a reinforcing layer in the order of the second angle layer and the second straight layer, and the second angle layer has a thickness of 0.04.
A lightweight golf club shaft having a torsional strength of 120 N · m · degree or more and a weight of 30 to 45 g, which is up to 0.1 mm thick, has as its first gist, a prepreg in which reinforcing fibers are aligned in one direction and impregnated with a matrix resin. Wrap it around the core,
A method for manufacturing a golf club shaft, comprising forming a plurality of fiber-reinforced composite material layers in the order of a first angle layer, a first straight layer, a second angle layer, and a second straight layer from the inside over the entire length of the shaft, and curing the same. The prepreg forming the second angle layer has a fiber basis weight of 18 to 55 g / m ² ,
A second gist of the present invention is a method for manufacturing the above lightweight golf club shaft having a thickness of 0.05 mm or less.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The reinforcing fibers constituting the FRP of the lightweight shaft of the present invention are not particularly limited as long as they are fibers usually used as reinforcing fibers for FRP, but para-aromatic polyamide, high-strength polyethylene. Inorganic fibers and metal fibers such as organic reinforcing fibers, carbon fibers, glass fibers, boron fibers, silicon carbide fibers, alumina fibers, and tyranno fibers. It is also possible to use two or more of these fibers in combination. In the present invention, as the reinforcing fiber, it is not necessary to partially or entirely use the reinforcing fiber having a particularly high elasticity as described in the prior art.

Further, as the FRP of the present invention, the matrix resin constituting the FRP of the lightweight shaft may be any resin which is generally known as the matrix resin of FRP, and is not particularly limited, but epoxy resin, Thermosetting resins such as unsaturated polyester resins, vinyl ester resins, polyimide resins and polybismaleimide resins are common. Of course, even if a thermoplastic resin is used as the matrix resin, the essential part of the present invention does not change.

The fiber-reinforced composite material layer forming the shaft described below is generally formed by using a so-called prepreg in which the above-mentioned reinforcing fibers are aligned and impregnated with the above-mentioned matrix resin. Unit weight,
The resin content and the like are not particularly limited, but the required thickness of each layer,
It is selected appropriately from the winding diameter.

The light-weight shaft of the present invention has a four-layer structure consisting of a first angle layer, a first straight layer, a second angle layer, and a second straight layer from the inside as the main structure over the entire length of the shaft. 0.04-0.1m
A thickness of m is necessary for weight reduction without changing the characteristics of the shaft and the outer diameter of the shaft.

Of course, in addition to the first and second straight layers, the first and second angle layers, for the purpose of improving the crushing strength, reinforcing the tip portion, and adjusting the diameter, etc., within a range that does not impair the object of the present invention. It goes without saying that other layers may be provided.

The thickness of the first angle layer is not particularly limited as long as it is the thickness usually found in FRP shafts, but the strength against the force acting in the diametrical direction of the shaft (crushing strength) is maintained at the same level as a normal shaft. To prevent the occurrence of vertical cracks when removing the core metal that serves as the mold during manufacturing, 0.2
It is preferably about 0.4 mm thick.

Of course, it is not necessary that the shaft has the same thickness over the entire length, and the bending rigidity, which is the object of the present invention,
It is possible to freely design for the purpose of improving other characteristics without sacrificing bending strength, torsional rigidity, and torsional strength. For example, such a design change includes changing the thickness of the first angle layer at the small-diameter end portion of the shaft to that of the large-diameter end portion in order to improve torsional rigidity and torsional strength, as will be seen in the following examples. It can be listed as being twice as much.

Further, the total thickness of the first straight layer and the second straight layer may be about the same as the thickness of the straight layer of the two-layer structure shaft in which the total thickness is usually found. It is 0.2 to 0.4 mm.
The total thickness may be allocated to the first and second straight layers in consideration of the bending rigidity, bending strength, etc. of the FRP shaft, but both may have the same thickness.

It is appropriate for the FRP shaft that the thicknesses of the first and second straight layers are 0.1 to 0.2 mm and 0.1 to 0.2 mm, respectively, and a total of 0.2 to 0.4 mm. Most preferable in terms of imparting bending rigidity and bending strength.

The second angle layer has a thickness of 0.04 to
As described above, the thickness of 0.1 mm is necessary for weight reduction without changing the characteristics of the shaft and the outer diameter of the shaft, which is the object of the present invention.

The second angle layer having such a small thickness is
Carbon fiber prepreg MR340 manufactured by Mitsubishi Rayon Co., Ltd.
K020S (prepreg basis weight 38g / m ² , resin content 40%, thickness 0.025mm), MR340J050S
(Pre-preg fabric weight 87 g / m ² , resin content 37.9
%, Thickness 0.058 mm) and the like, and can be easily realized by using an ultrathin prepreg.

The prepreg for forming the second angle layer has a fiber basis weight of 18 to 55 g / m ² , more preferably 1
8-30 g / m ² ultra-thin prepreg (0.05 mm thick)
The following), for example, prepreg H manufactured by Mitsubishi Rayon Co., Ltd.
RX330M025S (25g / m ^{2 with} prepreg weight,
Resin content 45%, thickness 0.025 mm), MR340
The use of K020S is most advantageous for manufacturing the lightweight shaft of the present invention.

[0023]

EXAMPLES The present invention will be described more specifically with reference to examples. Hereinafter, the fiber direction described simply as "-°" always indicates the angle measured with respect to the longitudinal direction of the shaft.

(Prepreg) Table 1 shows the prepreg used in the examples.

[0025]

[Table 1]

(Measurement of Torsional Strength and Torsional Rigidity) Torsion test of golf club shaft certification criteria and criteria confirmation method (5 Industrial No. 2087 approved by the Minister of International Trade and Industry, October 4, 1993) established by the Product Safety Association. It was done according to.

Using a 5KN universal tester manufactured by Mechatronics Engineering Co., Ltd., the small-diameter end of the shaft is fixed, and the torque is applied to the large-diameter end. And

(Bending strength) T point (90 mm from the small diameter end), A point (175 mm) and B point (525) of the shaft
mm) and a C point (175 mm from the large diameter end) as a center and a three-point bending test was performed at a span of 300 mm (150 mm only at the T point) to show its strength. The indenter was 75 mmR and the support was 12.5 mmR.

(Measurement of Bending Stiffness) A large-diameter end of the shaft was fixed, and a load of 1 kg was applied to a position 10 mm from the small-diameter end to measure the amount of deflection.

(Embodiment 1) The following (1) to (4) are provided on a tapered core metal having a small diameter end outer diameter of 4 mm, a large diameter end outer diameter of 13.4 mm and a length of 1500 mm. Thus, the first angle layer, the first straight layer, the second angle layer, and the second straight layer were sequentially formed.

(1) When the prepreg is wound around a cored bar so that the fiber direction is + 45 °, the prepreg A is cut into two layers at the thin end and one layer at the large end. Also, the prepreg A was cut so that it would be the same when wound so that the fiber direction would be -45 °, and these prepregs were laminated so that the fiber direction was orthogonal. The laminated prepreg was wound on the core metal to form a first angle layer.

(2) When the prepreg B is wound around the first angle layer so that the fiber direction is 0 °, it is cut so that both the small-diameter end and the large-diameter end become one layer, and this is A first straight layer was formed by winding on one angle layer.

(3) When prepreg C is wound on this so that the fiber direction is + 45 °, prepreg A is cut so that both the small-diameter end and the large-diameter end become one layer, and the fiber The prepreg A was cut in the same manner when it was wound so that the direction was −45 °, and these prepregs were laminated so that the fiber direction was orthogonal. Wrap this laminated prepreg on the first straight layer,
A second angle layer was formed.

(4) When the prepreg C is wound around the second angle layer so that the fiber direction is 0 °, it is cut so that both the small-diameter end and the large-diameter end become one layer, and this is A second straight layer was formed by winding on the two angle layers.

A polypropylene tape having a width of 20 mm and a thickness of 30 mm was wound on the second straight layer at a pitch of 2 mm and placed in a curing oven at 145 ° C. for 240 minutes for curing.

After the polypropylene tape was stripped off and the core metal was pulled out, 10 from the small-diameter end and 10 from the large-diameter end.
mm was cut and removed to obtain a shaft having a weight of 30 g, a length of 1145 mm, an outer diameter small diameter side 6.4 mm, and an outer diameter large diameter side 14.3 mm. The shaft thus obtained was a shaft having the following characteristics.

Bending rigidity: 73 mm Bending strength: T point 70 kgf, A point 40 kgf, B point 4
0kgf, C point 40kgf Torsional rigidity: 6.3 degrees Torsional strength: 130N ・ m ・ degree

(Comparative Example 1) The second angle layer of Example 1 was not provided, but instead, the number of the prepregs A constituting the first angle layer and having the fiber directions of + 45 ° and -45 ° were respectively small. 2.1 layers at 1.1 and 1.1 at large diameter end
A weight of 3 was obtained in the same manner as in Example 1 except that the layer was formed.
A shaft having a weight of 0 g, a length of 1145 mm, an outer diameter small diameter side of 6.4 mm, and an outer diameter large diameter side of 14.3 mm was obtained. The shaft thus obtained was a shaft having the following characteristics.

Bending rigidity: 73 mm Bending strength: T point 70 kgf, A point 40 kgf, B point 4
0kgf, C point 40kgf Torsional rigidity: 6.3 degrees Torsional strength: 100N ・ m ・ degree

Example 2 On the same core metal used in Example 1, 90 ° as shown in the following (1) to (7).
The reinforcing layer, the first angle layer, the first straight layer, the second angle layer, the second straight layer, and the tip end reinforcing layer were sequentially formed.

(1) When the prepreg D is wound around a core metal so that the fiber direction is 90 °, the prepreg D is cut into an approximately trapezoidal shape so that one layer is formed at the thin diameter end and the large diameter end, It was wound around the cored bar to form a 90 ° reinforcing layer. (2) The first angle layer was formed in the same manner as in (1) of Example 1. (3) The first straight layer was formed in the same manner as in (2) of Example 1. (4) The second angle layer was formed in the same manner as in (3) of Example 1. (5) The second straight layer was formed in the same manner as in (4) of Example 1.

(6) When the prepreg E is wound around the second straight layer so that the fiber direction is 0 °, it is a trapezoidal shape having two small layers at the small diameter end and 300 mm from the small diameter end. It was cut into pieces and wound on the second straight layer to form a tip end reinforcing layer.

(7) When the prepreg F is wound around the tip end reinforcing layer so that the fiber direction is 0 °, it is cut into an approximately triangular shape so that the outer diameter of the small diameter end portion becomes 8.5 mm, and Was wound on the tip reinforcing layer to form a small diameter end diameter adjusting layer. The following is heat-cured in the same manner as in Example 1 to give a weight of 38.
A shaft having g, a length of 1145 mm, an outer diameter small diameter side of 8.5 mm, and a large diameter side of 15.6 mm was obtained. The shaft thus obtained was a shaft having the following characteristics.

Bending rigidity: 70 mm Bending strength: T point 120 kgf, A point 55 kgf, B point 55 kgf, C point 55 kgf Torsional rigidity: 6.3 degrees Torsional strength: 150 Nm / degree

[0045]

According to the present invention, bending rigidity, bending strength,
35% to 50% of conventional shafts while maintaining the characteristics and outer diameter of conventional shafts such as torsional rigidity and torsional strength
A lightweight shaft can be obtained.

Claims (2)

[Claims] 1. A golf club shaft comprising a plurality of fiber-reinforced composite material layers laminated, the first angle layer, the first straight layer, and the first angle layer from the inner side over the entire length of the shaft.
A second angle layer and a second straight layer have a reinforcing layer in this order, and the second angle layer has a thickness of 0.04 to 0.1 mm.
Torsional strength is 120 N ・ m ・ degree or more, weight 30-45 g
Lightweight golf club shaft. 2. A first angle layer, a first straight layer, a second angle layer and a second straight layer from the inside over the entire length of the shaft by winding a prepreg in which reinforcing fibers are aligned in one direction and impregnated with a matrix resin and wound around a core metal. A method for manufacturing a golf club shaft, comprising forming a plurality of fiber-reinforced composite material layers in order of layers and curing, wherein the prepreg forming the second angle layer has a fiber basis weight of 18 to 55 g / m ² and a thickness of 0.05 mm or less. A method for manufacturing a lightweight golf club shaft according to claim 1.