JP2009189554A - Golf club shaft - Google Patents

Abstract

[PROBLEMS] To reduce the shaft deformation at the moment of hitting a ball as much as possible, to obtain a stable launch angle and spin amount, and to have a high bending strength, so that the probability of breakage is very low. Provide club shaft.
A golf club shaft composed of a plurality of fiber reinforced resin layers, having an elastic modulus of 350 GPa or more and a tensile elongation of 1.2% or more at least in a portion extending from a small diameter end to 100 mm. A certain carbon fiber has a first fiber reinforced resin layer oriented in the axial direction of the shaft, and has an elastic modulus of 100 GPa or less and a tensile elongation of 1.2 at least in a portion extending from 150 mm to 200 mm from the small diameter end. % Or more of carbon fibers have a second fiber reinforced resin layer oriented in the shaft axis direction, so that the first fiber reinforced resin layer and the second fiber reinforced resin layer are not overlapped. The shaft for the golf club which is arranged.
[Selection] Figure 1

Description

  The present invention relates to a golf club shaft.

  It is known that the flight distance of a golf ball is determined by the initial velocity, launch angle, and spin rate of the ball. In order to improve the golf score, the stability of the flight distance is very important. Therefore, in order to obtain a stable flight distance, it is necessary to reduce the variation of these three elements. .

  The initial velocity, launch angle, and spin amount of the ball depend on the characteristics of the golf head, but the stability (motion) of the shaft at the moment of hitting the ball affects the stability of these three elements. In particular, the deformation of the small diameter portion of the golf club shaft has a great influence on these elements. If the rigidity of this partial shaft is increased, the amount of deformation of the shaft can be suppressed, so that these elements are known to be stable. ing.

  However, simply increasing the shaft rigidity of the small diameter portion of the golf club shaft has disadvantages such as a hard feeling and poor head return. In general, carbon fiber with high elastic modulus has low tensile strength. Therefore, if the amount of carbon fiber with high elastic modulus is excessively increased in order to increase the rigidity of the shaft, the strength of the shaft decreases, Breakage easily occurs. Furthermore, if the rigidity of this part is made too high, the toe down of the head will be suppressed too much, the ball will easily hit the lower part from the center of the head, the launch angle is low, and the trajectory has a large amount of backspin. It tends to lead to loss of flight distance.

  On the other hand, Patent Document 1 describes that variation in launch angle can be suppressed by increasing the bending rigidity of the shaft of 5 mm to 50 mm from the hosel portion of the club head.

  However, when the bending rigidity between 5 mm and 50 mm from the hosel part of the club head is increased as in Patent Document 1, the shaft rigidity of the hosel part of the club head becomes extremely low. There is a drawback that breakage tends to occur.

  Contrary to the above, if the shaft rigidity of the small diameter portion of the golf club shaft is lowered, there is an advantage that the return of the head is improved, the ball launch angle is increased, and the flight distance is easily improved. However, if the shaft rigidity in the vicinity of the head is too low, the hit points are likely to vary, and there is a demerit that the flying distance is not stable. Further, if the amount of carbon fiber used is reduced in order to reduce the shaft rigidity, the strength of the shaft is lowered and the shaft is liable to break.

  On the other hand, in Patent Documents 2 and 3, the use of carbon fibers of 5 to 150 GPa as the reinforcing layer makes it possible to reduce the bending rigidity of the shaft without reducing the strength.

However, in Patent Documents 2 and 3, although it is possible to reduce the shaft rigidity without reducing the strength, it is not possible to obtain a stable launch angle and spin amount.
Japanese Patent No. 3518783 Japanese Patent No. 3296970 Japanese Patent No. 3317619

  The present invention has been made in view of the above circumstances, can suppress the deformation of the shaft narrow diameter portion at the moment of hitting the ball as much as possible, it is possible to obtain a stable launch angle, spin amount, And since it has high bending strength, it aims at the shaft for golf clubs with very little probability of breaking.

In order to achieve the above object, the present invention employs the following configuration.
(1) A first fiber reinforced resin layer in which carbon fibers having an elastic modulus of 350 GPa or more and a tensile elongation of 1.2% or more are oriented in the shaft axis direction at least in a portion extending from the small diameter end to 100 mm. A second fiber reinforced with carbon fiber having an elastic modulus of 100 GPa or less and a tensile elongation of 1.2% or more at least in a portion extending from 150 mm to 200 mm from the small-diameter end thereof. A golf club shaft having a resin layer, wherein the first fiber reinforced resin layer and the second fiber reinforced resin layer are arranged so as not to overlap each other.
(2) The thickness of the first fiber reinforced resin layer in which the carbon fiber having the elastic modulus of 350 GPa or more and the tensile elongation of 1.2% or more is oriented in the shaft axial direction is 0.125 mm or less. The golf club shaft according to (1).
(3) The thickness of the second fiber reinforced resin layer in which the carbon fiber having the elastic modulus of 100 GPa or less and the tensile elongation of 1.2% or more is oriented in the shaft axial direction is 0.125 mm or less. The golf club shaft according to (1) or (2).

  According to the golf club shaft of the present invention, the deformation of the small diameter portion of the shaft at the moment of hitting the ball can be suppressed as much as possible, so that it is possible to obtain a stable launch angle and spin amount, and a high bending strength. Therefore, it is possible to provide a golf club with a very low probability of breakage.

  For example, the golf club shaft of the present invention is formed by winding prepregs 21 to 27 having cut shapes as shown in patterns 1 to 7 in FIG. 1 around the mandrel 10 in the order of patterns 1 to 7 and then heat-curing. A plurality of fiber reinforced resin layers. In this golf club shaft, the number of windings is 1 at the portion extending from the small diameter end portion to the distance La, and the winding number is gradually decreased at the portion extending from the distance La to the distance Lc from the small diameter end portion. The prepreg 22a (first fiber reinforced resin layer) made of carbon fibers having a modulus of elasticity of 350 GPa or more and a tensile elongation of 1.2% or more and oriented in the longitudinal direction of the shaft, The number of windings gradually increases in the portion extending from the distance La to the distance Lc, the number of windings is 1 in the portion extending from the distance La + Lc to the distance Lb from the small diameter end, and the distance La + Lc + Lb to the distance Ld from the small diameter end. The prepreg 22b (second fiber reinforced resin layer) made of carbon fibers oriented in the longitudinal direction of the shaft, having an elastic modulus of 100 GPa or less, a tensile elongation of 1.2% or more, and the number of windings gradually decreasing in the span. ) It is location. Further, the prepreg 22a and the prepreg 22b have a shape integrated in close proximity as shown in the pattern 2 of FIG. In other words, the prepreg 22a and the prepreg 22b are arranged such that their cut surfaces are abutted so as not to overlap each other, and the shape is shown in the pattern 2 of FIG. Since the prepreg 22a and the prepreg 22b are not overlapped with each other, the effects of the respective elastic modulus and tensile elongation can be exhibited.

  Usually, a golf club shaft composed of a fiber reinforced resin layer is adjusted in length by cutting a small-diameter end and a large-diameter end after heat-curing. The distance La mentioned here is set so that the length becomes 100 mm after the cutting. That is, La = 110 mm when cutting the small-diameter end portion by 10 mm, and La = 120 mm when cutting the thin-diameter end portion by 20 mm.

The distance Lc is very important in relieving the bending stress concentration when the ball is hit. If the distance Lc is too short, it tends to break due to the bending stress at the time of impact, and if it is too long, the bending rigidity of the shaft becomes too high. Here, the distance Lc is preferably 20 mm to 50 mm, and more preferably 30 mm to 40 mm. Further, the distance Ld is also important for relaxing the stress concentration, and is preferably 20 mm to 70 mm, more preferably 30 mm to 60 mm.
The distance Lb is important for obtaining sufficient bending strength without significantly increasing the bending rigidity of the shaft. If the distance Lb is too short, it tends to break due to bending stress at the time of impact, and if too long, the distance of the shaft Mass becomes heavy. Here, the distance Lb is preferably 50 mm to 100 mm, and more preferably 70 to 80 mm. That is, the distance Lb is at least a portion extending from 150 mm to 200 mm from the small diameter end of the shaft.

As the matrix resin constituting the golf club shaft of the present invention, a thermoplastic resin or a thermosetting resin can be used, but a thermosetting resin is preferably used.
As the thermoplastic resin, polyamide resins, polyacrylate resins, polystyrene resins, polyethylene resins, and mixed resins thereof can be used. On the other hand, as thermosetting resins, epoxy resins, unsaturated polyester resins, phenol resins, urea resins, melamine resins, diallyl phthalate resins, urethane resins, polyimide resins, and mixed resins thereof are used. Can be used. Among these, epoxy resins are most preferably used because they have a low cure shrinkage and high rigidity and toughness.

As the fibers constituting the golf club shaft of the present invention, inorganic fibers such as metal fibers, boron fibers, carbon fibers, glass fibers, and ceramic fibers, aramid fibers, and other high-strength synthetic fibers can be used. Inorganic fibers are preferably used because of their light weight and high strength. Among these, carbon fiber is optimal because it is excellent in specific strength and specific rigidity.
These fibers can be used alone or in combination. Further, any length of fibers such as long fibers, short fibers, and mixed fibers thereof may be used.

  The carbon fiber used for the prepreg 22a needs to have a carbon fiber elastic modulus of 350 GPa or more. If the elastic modulus is less than 350 GPa, sufficient bending rigidity cannot be obtained at the small diameter portion of the golf club shaft, so that variation in hitting points becomes large. Further, the tensile elongation of the carbon fiber needs to be 1.2% or more. This is because if the tensile elongation is less than 1.2%, the probability of the shaft breaking during the deformation of the shaft at the time of hitting the ball becomes extremely high. As such a carbon fiber, a PAN-based high-elasticity carbon fiber using polyacrylonitrile fiber as a raw material is suitable.

  The thickness of the prepreg 22a is preferably 0.125 mm or less. If the thickness of the prepreg 22a is larger than 0.125 mm, the rigidity of the golf club shaft small diameter portion becomes too high, the feeling is not good, the head toe down is suppressed too much, and the lower part than the center of the head. The ball is easy to hit, the launch angle is low, and the trajectory has a large amount of backspin.

  The carbon fiber used for the prepreg 22b needs to have an elastic modulus of the carbon fiber of 100 GPa or less. If the elastic modulus is higher than 100 GPa, the rigidity of the shaft at this part becomes too high, the feeling is not good, or the toe down of the head is suppressed too much, and it becomes easy for the ball to hit below the center of the head and launch. Since the trajectory has a low angle and a large amount of backspin, it tends to lead to a loss of flight distance. As such a carbon fiber, a pitch-based low-elasticity carbon fiber using pitch as a raw material is suitable.

  The thickness of the prepreg 22b is preferably 0.125 mm or less. If the thickness of the prepreg 22a is greater than 0.125 mm, the shaft will be too stiff and the feeling will be poor, or the toe down of the head will be restrained too much and the ball will hit below the center of the head. The trajectory is low, the launch angle is low, and the trajectory has a large amount of backspin.

  According to the golf club shaft according to the embodiment of the present invention described above, the shaft extends from the small diameter end portion to the distance La (at least from the small diameter end of the shaft to 100 mm). Since the prepreg 22a (first fiber reinforced resin layer) in which carbon fibers having an elastic modulus of 350 GPa or more and a tensile elongation of 1.2% or more are oriented in the shaft axis direction is disposed, the ball is hit. Instantaneous shaft deformation can be suppressed as much as possible, so that a stable launch angle and spin amount can be obtained. Further, according to this golf club shaft, at least a portion extending from a distance La + Lc from the small-diameter end of the shaft to a distance La + Lc + Lb from the small-diameter end (at least a portion extending from 150 mm to 200 mm from the small-diameter end of the shaft). In addition, since a prepreg 22b (second fiber reinforced resin layer) in which carbon fibers having an elastic modulus of 100 GPa or less and a tensile elongation of 1.2% or more are oriented in the shaft axial direction is disposed, high bending strength Thus, a golf club shaft with a very low probability of breakage can be obtained.

The effect of the present invention is more fully exhibited when applied to a so-called wood golf club shaft having a golf club length of 1041 mm to 1219 mm and a shaft mass of 40 g to 85 g.
The golf club shaft of the present invention is also suitable for combination with a large head. Examples of the large head include a large head having a volume of 380 cm ^{3 to} 460 cm ³ and an inertia moment of 3500 g · cm ^{2 to} 5900 g · cm ² . The golf club shaft of the present invention can obtain a stable launch angle and spin amount even when such a large head is mounted.

Next, the present invention will be described more specifically based on examples.
The materials for the golf club shafts produced in Example 1 and Comparative Examples 1 and 2 are shown below.
Prepreg A: Carbon fiber prepreg HRX350C125S (thickness 0.098 mm, manufactured by Mitsubishi Rayon Co., Ltd.)
Prepreg B: Carbon fiber prepreg E052AA-10N (thickness 0.109 mm, manufactured by Nippon Graphite Fiber Co., Ltd.)
Prepreg C: Carbon fiber prepreg TR350C100S (thickness 0.084 mm, manufactured by Mitsubishi Rayon Co., Ltd.)
Prepreg D: Carbon fiber prepreg MR350C175S (thickness 0.141 mm, manufactured by Mitsubishi Rayon Co., Ltd.)
Prepreg E: Carbon fiber prepreg MR350C150S (thickness 0.127 mm, manufactured by Mitsubishi Rayon Co., Ltd.)
Prepreg F: Carbon fiber prepreg TR350C150S (thickness 0.127 mm, manufactured by Mitsubishi Rayon Co., Ltd.)
Prepreg G: Carbon fiber prepreg MR350E125S (thickness 0.113 mm, manufactured by Mitsubishi Rayon Co., Ltd.)

Example 1
<Mandrel>
A mandrel 10 (made of iron) having the shape shown in FIG. 2 was prepared. The mandrel 10 has an overall length L3, the outer diameter of which gradually increases linearly from the narrow end P1 to the position (switching point) P2 of the length L1, and from the switching point P2 to the length L2. It consists of an iron cylinder whose outer diameter is constant up to the large diameter end P3. The specific outer diameter, length, and taper degree of each part of the mandrel 10 according to the present embodiment are as follows.
The outer diameter of the small diameter end P1 is 4.00 mm, the outer diameter of the switching point P2 is 13.50 mm, the same outer diameter from the switching point P2 to the large diameter end P3, and the outer diameter is 13.50 mm. The length L1 from the small diameter end P1 to the switching point P2 is 950 mm, and the length L2 from the switching point P2 to the large diameter end P3 is 550 mm. The overall length L3 of the mandrel 10 is 1500 mm. Further, the taper degree from the small diameter end P1 to the switching point P2 is set to 10.00 / 1000.

<Cutting and winding prepreg>
Various prepregs (prepregs A to G) were cut into shapes shown in patterns 1 to 7 in FIG.
That is, in the pattern 1, the prepreg A cut by + 45 ° and the prepreg A cut by −45 ° with respect to the longitudinal axis direction of the shaft were bonded to each other so as to be substantially shifted by a half circumference. Then, the size of the prepreg A obtained by bonding the two sheets was adjusted so that the total length was 1190 mm, the number of windings of the small-diameter end was 5.5, and the number of windings of the large-diameter end was 2.8.
In pattern 2, the prepregs A and B are sized so that the fibers are oriented in the longitudinal direction of the shaft, and La, Lb, Lc, and Ld in FIG. 3 are La = 110 mm, Lb = 80 mm, Lc = 30 mm, respectively. Ld = 60 mm, and the number of windings was adjusted to be 1 time. In addition, the prepreg A and the prepreg B of the pattern 2 of FIG. 3 are abutted with the cut surfaces, and are taped from above the release paper attached to one side of the prepreg A and the prepreg B. The release paper and the tape are peeled after the prepreg A and the prepreg B of the pattern 2 are wound around a mandrel described later.
In Pattern 3, the size of the prepreg C was adjusted so that the fibers were oriented in the longitudinal axis direction of the shaft, the total length was 600 mm, and the number of windings was one.
In patterns 4 to 6, the sizes of the prepregs D to F were adjusted so that the fibers were oriented in the longitudinal axis direction of the shaft, the total length was 1190 mm, and the number of windings was one.
In pattern 7, the size of the prepreg G was adjusted so that the fibers were oriented in the longitudinal direction of the shaft and the outer diameter of the narrow end portion was about 8.70 mm.
Note that the prepregs A to G shown in the patterns 1 to 7 in FIG. 3 correspond to the prepregs 21 to 27 shown in the patterns 1 to 7 in FIG. 1, respectively.

Next, each cut prepreg was wound around the mandrel 10 in the order of patterns 1-7. As for winding, 20 mm from the small-diameter end of the mandrel was used as the winding end.
Next, a heat-shrinkable polypropylene tape (not shown) having a thickness of 20 μm and a width of 30 mm was wound and fixed at a winding pitch of 2 mm to obtain a shaft base tube formed on the mandrel 10.

<Hardening of resin and polishing of shaft surface>
The shaft base tube was put in a curing furnace and heated at 145 ° C. for 2 hours to cure the resin of the prepreg, and then the polypropylene tape and the mandrel 10 were removed. Both ends of the obtained golf club shaft base tube were cut by 10 mm to a total length of 1170 mm. The cantilever flex of the shaft before polishing (the amount of deflection of the shaft small diameter end when a position of 920 mm from the small diameter end is fixed and a weight of 3 kg is hung on the position of 10 mm from the small diameter end of the shaft) is 133 mm. It was. Further, the outer diameter of the small diameter end of the golf club shaft blank before polishing was 8.77 mm, and the outer diameter of the large diameter end was 15.46 mm.

  The surface of the golf club shaft tube is polished with a cylindrical grinder so that the outer diameter of the narrow end is 8.50 mm and the cantilever flex is 148 mm. Thus, the golf club shaft of Example 1 is obtained. It was.

  The weight of the golf club shaft of Example 1 was 68.1 g, the shaft twist angle (fixed at a position of 1035 mm from the shaft small diameter end, and 138.5 kgf from the shaft small diameter end to the position from the shaft small diameter end to 50 mm) The angle at which the shaft was twisted when a torque of mm was applied) was 3.3 degrees.

<Attaching the golf club head and grip>
A commercially available titanium golf club head for drivers (volume: 430 cm ³ , mass: 203 g, loft angle: 10.5 °) was attached to the golf club shaft of Example 1 at the small-diameter end with an epoxy resin adhesive. Further, the end portion of the shaft with a large diameter was cut by 75 mm, and a commercially available rubber grip was attached to the shaft using a double-sided tape to produce the golf club of Example 1.

<Evaluation of hit ball>
The golf club of Example 1 was hit with a golf ball 10 times using a golf trial hitting robot “SHOTROBO-IV” manufactured by Miyamae Co., Ltd., and measurement such as flight distance measurement was performed using “AccumVector” manufactured by AccuSport. Table 1 shows the measurement results. In Table 1, the average values of side spins are those measured with 10 shots, with the right rotation (hook) being positive (+) and the left rotation (slice) being negative (-). The total value was calculated by adding and dividing the total value by the number of hit balls (10 times).

<3-point bending test>
The golf club shaft of Example 1 was subjected to a three-point bending test in accordance with a three-point bending test method for a C-shaped shaft in “Golf Club Shaft Certification Criteria and Standard Confirmation Method” defined by the Product Safety Association. In addition, this time, the test of the load point position T (90 mm from the shaft small diameter end portion) and the load point position A (175 mm from the shaft small diameter end portion) in the “Golf Club Shaft Certification Criteria and Standard Confirmation Method” were each tested. It was carried out one by one. FIG. 4 shows an outline of this three-point bending strength test apparatus. The results of measuring the three-point bending strength of the shaft are shown in Table 2.

(Comparative Example 1)
As shown in FIG. 5, a shaft was produced in the same manner as in Example 1 except that the pattern 2 was cut into the same size as that in Example 1 by using only the prepreg A, and each evaluation was performed. The evaluation results are shown in Tables 1 and 2.

(Comparative Example 2)
As shown in FIG. 6, a shaft was produced in the same manner as in Example 1 except that the pattern 2 was cut into the same size as that in Example 1 by using only the prepreg B, and each evaluation was performed. The evaluation results are shown in Tables 1 and 2.

  As shown in Table 1, in the golf club using the golf club shaft in Example 1, the launch angle and the backspin amount were most stable, and as a result, the average flight distance was the largest. In Comparative Example 1, the launch angle and the side spin amount were stable, but the back spin amount increased, resulting in a loss of the average flight distance. In Comparative Example 2, the behavior of the head was not stable, the hook became strong, and the average flight distance was lost.

  As shown in Table 2, the golf club shafts in Example 1 and Comparative Example 2 have high three-point bending strength in good balance at both the load point positions T and A, whereas the golf club shafts in Comparative Example 2 In the shaft, the load point position T had a high three-point bending strength, but the load point position A was lower than the former.

  Thus, the golf club shaft in Example 1 has a high three-point bending strength, and can provide a stable launch angle and a stable backspin amount.

It is explanatory drawing which shows the cutting shape of the prepreg which shows one Embodiment of the shaft for golf clubs of this invention, and winding order. 1 is a schematic explanatory diagram of a mandrel 10. FIG. It is explanatory drawing which shows the cutting shape of the prepreg used for manufacture of the golf shaft in Example 1, and the winding order to the metal core. It is the schematic of the three-point bending test apparatus of the shaft for golf clubs. 5 is an explanatory diagram showing a cutting shape of a prepreg used for manufacturing a golf shaft in Comparative Example 1 and a winding order around a cored bar 10. FIG. 6 is an explanatory diagram showing a cutting shape of a prepreg used for manufacturing a golf shaft in Comparative Example 2 and a winding order around a cored bar 10. FIG.

Explanation of symbols

22a Prepreg (first fiber reinforced resin layer)
22b Prepreg (second fiber reinforced resin layer)

Claims (3)

A golf club shaft comprising a plurality of fiber reinforced resin layers,
At least a portion extending from the small diameter end to 100 mm has a first fiber reinforced resin layer in which carbon fibers having an elastic modulus of 350 GPa or more and a tensile elongation of 1.2% or more are oriented in the shaft axis direction, And a second fiber reinforced resin layer in which carbon fibers having an elastic modulus of 100 GPa or less and a tensile elongation of 1.2% or more are oriented in the shaft axial direction at least in a portion extending from 150 mm to 200 mm from the small diameter end. Have
The shaft for golf clubs, wherein the first fiber reinforced resin layer and the second fiber reinforced resin layer are arranged so as not to overlap each other.   The thickness of the first fiber reinforced resin layer in which carbon fibers having an elastic modulus of 350 GPa or more and a tensile elongation of 1.2% or more are oriented in the shaft axial direction is 0.125 mm or less. The shaft for golf clubs as described.   The thickness of the second fiber reinforced resin layer in which carbon fibers having an elastic modulus of 100 GPa or less and a tensile elongation of 1.2% or more are oriented in the shaft axial direction is 0.125 mm or less. Or the shaft for golf clubs of 2.

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