JPH08308969A - Shaft for golf club made of fiber reinforced plastic - Google Patents

Abstract

PURPOSE: To reduce an impact being applied to hands when a ball is hit by respectively laminating a plurality of bias reinforcing layers wherein a reinforcing fiber has an orientation angle to the shaft longitudinal direction, straight reinforcing layers with a parallel order, on the outside of the bias reinforcing layers, and bias reinforcing layers, on the further outside. CONSTITUTION: A shaft 1 made of FRP is constituted of a first bias reinforcing layer 2, straight reinforcing layer 3, and second bias reinforcing layer 4. The first bias reinforcing layer 2 is formed by alternately laminating a plurality of bias reinforcing members 2A wherein a reinforcing fiber has an orientation angle to the longitudinal direction of the shaft 1. The straight reinforcing layer 3 is constituted of a plurality of straight reinforcing members 3A wherein a reinforcing fiber is arranged in parallel with the longitudinal direction of the shaft 1. The second bias reinforcing layer 4 is constituted by alternately laminating a plurality of bias reinforcing members 4A which have an orientation angle. By this method, an impact due to a twist vibration can be softened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a golf club shaft made of fiber reinforced plastics (made of FRP) (hereinafter, simply referred to as an FRP shaft), which is excellent in impact at the time of hitting a ball. It is an object of the present invention to provide a shaft made of FRP having vibration isolation and impact resistance.

[0002]

2. Description of the Related Art Conventionally, as a shaft made of FRP,
For example, a carbon fiber reinforced plastic shaft (hereinafter simply referred to as a CFRP shaft by winding a prepreg obtained by impregnating aligned carbon fibers with a thermosetting resin around a mandrel which is a core metal, and then heating and curing the prepreg A sheet winding method for molding
Similarly, a manufacturing method such as a filament winding method in which a carbon fiber impregnated with a thermosetting resin is directly wound around a mandrel, heated and cured, and then the mandrel is extracted to form a CFRP shaft is known.

Conventionally, in the case of the sheet winding method, in order to maintain the torsional strength and the compressive strength, when the reinforcing fiber is set to 0 ° in the longitudinal direction of the shaft, the orientation angle is about +3.
A bias reinforcing layer oriented in the range of 0 ° to + 45 °;
A plurality of bias reinforcing layers oriented in an orientation angle range of about −30 ° to −45 ° are alternately laminated, and reinforcing fibers are provided outside the bias reinforcing layers to maintain bending strength in the longitudinal direction of the shaft. The shaft is constructed by laminating a plurality of straight reinforcing layers oriented in parallel with
The RP shaft is generally designed by considering the balance between torsional strength and compressive strength by selecting the material, the orientation angle, the number of turns, the diameter, the number of reinforcing layers, and the like.

[0004]

However, these conventionally known FRP shafts have the following problems. That is, a golf club equipped with a FRP shaft currently on the market has drawbacks such that when hitting at a position other than the sweet spot of the head, a large impact is felt and the hand becomes numb or resonates with the hand. However, the cause of these impacts was not clearly known. Therefore, various methods have been taken to reduce the impact at the time of hitting a ball, for example, as disclosed in Japanese Utility Model Laid-Open No. 6-31771.
BACKGROUND ART A grip having a grip main body made of a shock absorbing resin is known in order to absorb a shock. In these grips, the effect of damping the vibration accompanying the impact is certainly recognized, but there is essentially no effect of suppressing the vibration itself, and when the ball is hit with the sweet spot of the head removed, the hand gets numb, A great effect could not be expected to prevent the phenomenon such as the noise on the hands. Therefore, the inventors of the present application measure the acceleration / distortion at the time of actual hitting and the sensory test and analyze the data to determine the cause of the impact felt by the hand as to the primary cause of the golf club immediately after the ball impact. It was found that it was caused by bending vibration and torsional vibration.

That is, the vibration generated immediately after the impact is 1
It is composed of secondary vibration, secondary vibration, tertiary vibration, and other bending vibrations and torsional vibrations from primary to higher orders. Among these, the inventors of the present application have found out that the impact applied to the hand is largely caused by the primary bending vibration and the torsional vibration. In particular, they found that the magnitude of the vibration of the torsional vibration (vibration level) and the natural frequency of the torsional vibration had a great influence. FIG. 2 shows the time series data of the torsional strain of the FRP shaft near the grip during actual driving, and FIG. 3 shows an example of the result of frequency analysis of the time series data of FIG. From these results, it was found that the smaller the maximum amplitude of the torsional vibration and the larger the natural frequency, the smaller the impact on the hand.

[0006]

That is, the FRP of the present invention
In the manufactured shaft, reinforcing fibers are alternately laminated in plural with respect to the longitudinal direction of the shaft so as to form a first bias reinforcing layer, and on the outer side of the first bias reinforcing layer, A plurality of straight reinforcing members having reinforcing fibers arranged in parallel to the longitudinal direction of the shaft are laminated to form a straight reinforcing layer, and bias reinforcing members having an orientation angle are alternately arranged outside the straight reinforcing layer. The FRP shaft has a structure in which a plurality of second bias reinforcing layers are formed by laminating a plurality of layers.

In the FRP golf club shaft, a plurality of bias reinforcing members having reinforcing fibers having an orientation angle with respect to the longitudinal direction of the shaft are alternately laminated to form a first bias reinforcing layer. 1. A plurality of straight reinforcing members in which reinforcing fibers are arranged in parallel to the longitudinal direction of the shaft are laminated on the outside of the bias reinforcing layer 1 to form a straight reinforcing layer, and the straight reinforcing layer is further oriented on the outside of the straight reinforcing layer. A plurality of bias reinforcing members having an angle are alternately laminated to form a second bias reinforcing layer, and a shaft surface adjusting layer made of scrim cloth or the like is formed on the surface of the second bias reinforcing layer. FRP golf club shaft.

Further, in the FRP shaft 1, it is possible to orient the bias reinforcing layer in the range of about ± 20 to ± 60 ° when the longitudinal direction of the shaft is 0 °. .

In the FRP shaft, the orientation angle of the second bias reinforcing layer is within a range of about 200 mm to 600 mm from the butt end of the shaft, and the orientation angle of the bias reinforcing layer is 0 ° in the longitudinal direction of the shaft. At this time, the orientation angle is oriented within a range of about ± 20 to ± 60 °, and the elastic modulus of the reinforcing fibers used for these bias reinforcing layers is about 3.0 × 10 ⁴ kgf / mm ^{2 to} 7.5 ×.
A shaft made of FRP, characterized in that it is constructed by using one having a range of 10 ⁴ kgf / mm ² .

Further, in the FRP shaft, the orientation angle of the second bias reinforcing layer is within a range of about 200 mm to 400 mm from the butt end of the shaft, and the orientation angle of the bias reinforcing layer is 0 ° in the longitudinal direction of the shaft. At this time, the orientation angle is oriented within a range of about ± 45 °, and the elastic modulus of the reinforcing fiber used for the bias reinforcing layer is about 3.0 × 10 ⁴ kgf / mm ^{2 to} 6.0 × 10 ⁴ kg.
It is a shaft made of FRP, characterized in that it is constructed by using one having a range of f / mm ² .

In the FRP shaft of the present invention, as described above, the smaller the maximum amplitude of the torsional vibration is and the larger the natural frequency is, the smaller the impact on the hand is. Then, various measurements were performed using a golf club having these prototype FRP shafts assembled. That is, as shown in FIGS. 6 to 10, the transfer function of force-torsional vibration (strain) when each point on the face surface of the golf club head was hit with an impact hammer was measured. As a result, it is possible to analyze the torsional vibration that causes the impact felt by the hand. From these results, approximately 200 mm from the butt end of the FRP shaft
It was found that the torsional rigidity of the butt portion in the range of 600 mm to 600 mm greatly affects the impact felt by the hand. Further, among them, it has been found that the torsional rigidity of the butt portion within a range of about 400 mm from the butt end of the FRP shaft has a great influence on the impact particularly felt by the hand.
Therefore, by increasing the torsional rigidity of these parts,
It has been found that the natural frequency of the torsional vibration is increased and the vibration level is lowered, so that the impact that affects the hand when hitting the ball can be reduced.

From the above, as a means for improving the torsional rigidity of the butt portion of the FRP shaft, a method of increasing the shear elastic modulus of the member used in the butt portion can be considered. In particular, the bias reinforcing layer has high elasticity. It was found to be effective to use this reinforcing fiber and arrange this bias reinforcing layer in the outermost layer as much as possible. Further, the theoretically most advantageous method for improving the torsional rigidity is to set the orientation angle of the bias reinforcing layer to about ± 45 °.
Although the reinforcing fibers having an orientation angle close to this angle contribute to improving the torsional rigidity, it is advantageous to arrange the reinforcing fibers in the longitudinal direction in order to improve the bending elasticity. Therefore, when designing the parameters of both torsional rigidity and bending rigidity when the longitudinal direction is set at 0 °, it is desirable to use a highly elastic fiber in the orientation angle range of about ± 20 ° to ± 60 °. It is a thing.

[0013]

With the above-mentioned structure, the FR of the present invention
In the shaft made of P, approximately 200 mm from the butt end
It is possible to improve the torsional rigidity of the bat portion corresponding to the position up to 600 mm, increase the natural frequency of the torsional vibration that occurs when the ball is hit with the sweet spot removed, and lower the vibration level. It has become possible to reduce the numbness and noise of the. Further, when the second bias reinforcing layer is formed, it is possible to prevent the end portion of the bias reinforcing member from turning up because the end portion of the bias reinforcing member is strong by forming the shaft surface adjusting layer made of the scrim cloth or the like of the present invention. It prevents the curling up and keeps the shaft surface smooth.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One of the preferred embodiments of the FRP shaft according to the present invention will be described with reference to the drawings. That is, FIG.
As shown in (A) and (B), in the FRP shaft 1 of the present invention, a plurality of bias reinforcing members 2A in which reinforcing fibers have an orientation angle with respect to the longitudinal direction of the shaft are alternately laminated to form a first bias. A reinforcing layer 2 is formed, and a plurality of straight reinforcing members 3A in which reinforcing fibers are arranged in parallel to the longitudinal direction of the shaft are laminated on the outside of the first bias reinforcing layer 2 to form the straight reinforcing layer 3. Then, the FRP shaft 1 is characterized in that the second bias reinforcing layer 4 is formed by alternately laminating a plurality of bias reinforcing members 4A having an orientation angle outside the straight reinforcing layer 3.

Further, in the FRP golf club shaft 1, the first bias reinforcing layer 2 is formed by alternately laminating a plurality of bias reinforcing members 2A having reinforcing fibers having an orientation angle with respect to the longitudinal direction of the shaft. Then, on the outside of the first bias reinforcing layer 2, straight reinforcing members 3A in which reinforcing fibers are arranged in parallel to the longitudinal direction of the shaft.
To form a straight reinforcing layer 3, and further, a plurality of bias reinforcing members 4A having an orientation angle are alternately laminated outside the straight reinforcing layer 3 to form a second bias reinforcing layer 4, and The FRP golf club shaft is characterized in that a shaft surface adjusting layer 5 made of scrim cloth or the like is formed on the surface of the second bias reinforcing layer 4.

In the FRP shaft 1, the bias reinforcing layers 2 and 4 may be oriented within a range of about ± 20 to ± 60 ° when the longitudinal direction of the shaft is 0 °. It is possible.

Another preferred embodiment of the FRP shaft according to the present invention will be described below. (Embodiment 1) That is, FIG. 4 is an explanatory diagram regarding a winding method when a CFRP shaft is manufactured by the sheet winding method according to the present invention. First, the total length of the CFRP shaft is set to about 1120 mm, and two layers of the bias reinforcing member 2A, which is oriented as an innermost layer at about ± 45 ° with respect to the longitudinal direction of the shaft, is wound around the metal mandrel 11. To form a first bias reinforcing layer, and the straight reinforcing member 3A is provided outside the first bias reinforcing layer.
3 layers are wound around to form a straight reinforcing layer, and two types of tip reinforcing members 6 of two types, long and short, are wound around the outer side 1A of the straight reinforcing layer, 3 layers each, and further the straight reinforcing layer 3 Bias reinforcement member 4 oriented ± 45 ° with respect to the longitudinal direction of the shaft on the outer butt side 1B
A is alternately wound in three layers to form a second bias reinforcing layer, and the bias reinforcing member 2A has a high elastic modulus of about 5.00 × 10 ⁴ kgf / mm ² . A carbon fiber reinforcing member is used. Further, a high elastic carbon fiber reinforcing member having an elastic modulus of about 4.45 × 10 ⁴ kgf / mm ² is used as the bias reinforcing member 4A.
A high-strength carbon fiber reinforcing member having an elastic modulus of about 3.00 × 10 ⁴ kgf / mm ² is used for the tip reinforcing member 6 of A and two types of long and short.

As another embodiment of the FRP shaft 1 according to the present invention, as described above, the orientation angle of the second bias reinforcing layer 4 is about 200 mm to 600 mm from the butt end 1b of the FRP shaft 1. In the range, when the orientation angle of the bias reinforcing layer 4 is 0 ° in the longitudinal direction of the shaft, the orientation angle is oriented within a range of about ± 20 to ± 60 °, and the reinforcing fibers used for these bias reinforcing layers 4 are Elastic modulus of about 3.0 × 10 ⁴ kgf / mm
It is also possible to construct using ² to the range of ^{7.5 × 10 4 kgf / mm 2} .

Further, as another embodiment of the FRP shaft 1 according to the present invention, as described above, the second
When the orientation angle of the bias reinforcing layer 4 is within a range of approximately 200 mm to 400 mm from the butt end 1b of the FRP shaft 1, the orientation angle of the bias reinforcing layer 4 is approximately ± 45 when the longitudinal direction of the shaft is 0 °. And the elastic modulus of the reinforcing fibers used in the bias reinforcing layer 4 is about 3.0 × 10 ⁴ kgf / mm ^{2 to} 4.4.
It is also possible to use those having a range of 5 × 10 ⁴ kgf / mm ² .

In addition, as the FRP shaft 1 according to the present invention, a prepreg obtained by impregnating carbon fiber, glass fiber, aramid fiber or the like with a thermosetting resin such as epoxy resin is cut into a substantially rectangular shape with a core metal. A sheet winding method in which a mandrel is wound and heated and cured, and then the mandrel is removed, or a roving in which the above-mentioned fiber is impregnated with a thermosetting resin is directly wound around the mandrel, heated and cured, and then the mandrel is removed, and the like. It is also possible to manufacture the shaft by using a conventionally known shaft manufacturing method. Furthermore, in the present invention,
The second bias reinforcing layer can be formed mainly on the butt side as described above, and can be formed of the entire length of the shaft.

Further, as the form of the reinforcing fiber forming the shaft surface adjusting layer 5 made of scrim cloth, etc., by using scrim cloth made of carbon fiber, glass fiber or aramid fiber woven fabric, mat or non-woven fabric, It is possible to prevent rising of the end portion of the bias reinforcing member and form a good shaft surface. In the FRP shaft 1 according to the present invention, it goes without saying that a coating film layer made of paint is formed as the outermost layer.

Next, a CFRP which is an embodiment of the present invention
An explanation will be given by taking a shaft made as an example. That is, FIG. 5 shows a diagram in which the torsional rigidity distribution in the entire length of the CFRP shaft is compared between the CFRP shaft of the present invention and the conventional product. The conventional product is one of the lowest torque CFRP shafts on the market, but the CFRP shaft of the present invention has a butt-side torsional rigidity that is about twice that of the conventional product. I understand.

Next, FIG. 6 shows a block diagram relating to the measurement of torsional vibration deeply related to the impact felt by the hand. Furthermore, FIG.
Indicates a sweet spot point of the head 7 generated when the face surface of the head 8 of the golf club 7 is hit with the impact hammer 9. That is, to explain the block diagram shown in FIG. 6, each point on the face surface of the head 8 of the golf club 7 is hit with an impact hammer 9, and the force at that time is attached to the impact hammer 9 and a FRP shaft. 330mm from the butt end of 1
The FFT analyzer receives the signal from the strain gauge 10 for twist measurement attached to the surface of the shaft at the position, and calculates the transfer function.

An example of this transfer function is shown in FIG. The frequency range having the peak of the waveform shown in FIG. 8 is the torsional vibration. By this frequency and peak height (gain),
It is possible to grasp the magnitude of the impact due to the torsional vibration.
Next, the gain of the transfer function when hitting each point on the face surface is compared between a golf club equipped with the CFRP shaft of the present invention and a golf club equipped with a conventional CFRP shaft. And shown in FIG.

[0025]

From the above results, the golf club equipped with the CFRP shaft of the present invention has a conventional CFR.
About 1.5 ~ than a golf club equipped with a P shaft
It can be seen that it is reduced by 7.8 dB. Further, the golf club equipped with the CFRP shaft of the present invention has a natural frequency of torsional vibration of about 36 Hz to 43H.
It has been improved to z, and these results also show that it has an effect of alleviating the impact due to the torsional vibration.

Next, a sensory test was conducted on the impact when the golf club head was hit at various points on the face surface of the head, and the superiority of the product equipped with the CFRP shaft of the present invention was confirmed. This sensory test was carried out on five golfers of intermediate and intermediate level, and the ball was hit at various points on the face surface, and the degree of impact at the time of hitting the ball was evaluated by a 5-point evaluation method. In order to be able to specify the actual ball hitting point, a mark was made on the ball with a water-based pen at the part where the head comes into contact, and where each ball was hit was set on the face X , Y coordinate (geometrical center is zero)
The results of this sensory test are recorded in FIG. 11 and FIG.
It is shown in FIG. That is, the points evaluated as having no impact are shown by □, but as is clear from FIG. 11, it can be seen that the present invention is more scattered than the conventional products. It also agrees well with the result of the transfer function.

Further, in the FRP shaft of the present invention, since the end portion of the second bias reinforcing member has a strong elasticity, the end portion is turned up. By forming a shaft surface adjustment layer made of scrim cloth or the like, This has the effect of preventing curling up and keeping the shaft surface smooth. As described above, F in the present invention
The RP shaft suppresses the torsional vibration that occurs when the hitting point deviates from the sweet spot and hits, and the numbness and reverberation of the hand can be significantly improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing a CFRP shaft that is an embodiment of the present invention.

[Fig. 2] Around the grip when actually hitting (330 from the grip end)
(mm) position is a graph showing a time series of twist distortion.

FIG. 3 is a graph obtained by frequency-analyzing the time-series data of FIG.

FIG. 4 is an explanatory view showing a laminated state of a CFRP shaft according to the present invention.

FIG. 5 is a graph comparing the torsional rigidity distributions over the entire length of a CFRP shaft that is an embodiment of the present invention and a conventional low torque CFRP shaft.

FIG. 6 is a block diagram of torsional vibration measurement.

FIG. 7 is an explanatory diagram showing points on the face surface of a golf club head that is hit with an impact hammer.

FIG. 8 is a diagram showing an example of a transfer function of force-torsional vibration (strain).

FIG. 9 is a graph showing torsional vibration values at each striking point on the face of a golf club equipped with a CFRP shaft according to the present invention.

FIG. 10 is a graph showing the torsional vibration value at each striking point on the face of a golf club equipped with a conventional low-torque CFRP shaft.

FIG. 11 is a graph showing the distribution of impact functional values felt by the hand at each striking point on the face surface of a golf club equipped with a CFRP shaft that is an embodiment of the present invention.

FIG. 12 is a graph showing a distribution of impact functional values perceived by the hand at each striking point on the face surface of a golf club equipped with a conventional low-torque CFRP shaft.

[Explanation of symbols]

 1 FRP Shaft 1A Tip Side 1a Tip End 1B Butt Side 1b Butt End 2 First Bias Reinforcement Layer 2A Bias Reinforcement Member 3 Straight Reinforcement Layer 3A Straight Reinforcement Member 4 Second Bias Reinforcement Layer 4A Bias Reinforcement Member 5 Shaft Surface Adjustment Layer 6 Tip reinforcing member 7 Golf club 8 Head 9 Impact hammer 10 Strain gauge 11 Mandrel

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tea garden Kiyotaka 1-12-35, Minami Kohoku, Suminoe-ku, Osaka City, Osaka Prefecture Mitsuno Co., Ltd.

Claims (5)

[Claims] 1. In a FRP golf club shaft, a plurality of bias reinforcing members, in which reinforcing fibers have an orientation angle with respect to the longitudinal direction of the shaft, are alternately laminated to form a first bias reinforcing layer. 1. A plurality of straight reinforcing members in which reinforcing fibers are arranged in parallel to the longitudinal direction of the shaft are laminated on the outside of the bias reinforcing layer 1 to form a straight reinforcing layer, and the straight reinforcing layer is further oriented on the outside of the straight reinforcing layer. An FRP golf club shaft having a structure in which a plurality of bias reinforcing members each having an angle are alternately laminated to form a second bias reinforcing layer. 2. A FRP golf club shaft, wherein a plurality of bias reinforcing members having reinforcing fibers having an orientation angle with respect to the longitudinal direction of the shaft are alternately laminated to form a first bias reinforcing layer, 1. A plurality of straight reinforcing members in which reinforcing fibers are arranged in parallel to the longitudinal direction of the shaft are laminated on the outside of the bias reinforcing layer 1 to form a straight reinforcing layer, and the straight reinforcing layer is further oriented on the outside of the straight reinforcing layer. A plurality of bias reinforcing members having an angle are alternately laminated to form a second bias reinforcing layer, and a shaft surface adjusting layer made of scrim cloth or the like is formed on the surface of the second bias reinforcing layer. FRP golf club shaft. 3. In the shaft for a FRP golf club, the orientation angle of the first bias reinforcing layer or the second bias reinforcing layer is about ± 20 to ± when the longitudinal direction of the shaft is 0 °. The FR according to claim 1 or 2, wherein the FR is oriented so as to be in the range of 60 °.
P golf club shaft. 4. In the shaft for a golf club made of FRP, the orientation angle of the second bias reinforcing layer is within a range of about 200 mm to 600 mm from the butt end of the shaft, and the orientation angle of the bias reinforcing layer is 0 in the longitudinal direction of the shaft. And the orientation angle is about ± 20 to ± 60 °, and the elastic modulus of the reinforcing fiber used for the bias reinforcing layer is about 3.0 × 10 ⁴ kgf / mm ^{2 to} 7.5 ×. The FRP golf club shaft according to claim 1, 2 or 3, wherein the shaft is used in the range of 10 ⁴ kgf / mm ² . 5. In the FRP golf club shaft, the orientation angle of the second bias reinforcing layer is within a range of about 200 mm to 400 mm from the butt end of the shaft, and the orientation angle of the bias reinforcing layer is 0 in the longitudinal direction of the shaft. And the orientation angle is about ± 45 °, and the elastic modulus of the reinforcing fibers used for the bias reinforcing layer is about 3.0 × 10 ⁴ kgf / mm ^{2 to} 6.0 × 1.
The FRP according to claim 1, 2, 3, or 4, wherein the FRP is constructed by using one having a range of 0 ⁴ kgf / mm ^2.
Made golf club shaft.