JPH1176479A - Shaft for golf club and golf club - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a carry by specifying flexural rigidity and torsional rigidity in the tip part and the grip side of a shaft using a fiber reinforced plastic, setting the flexural rigidity on the grip side slightly higher, and setting the flexural rigidity in the tip part lower. SOLUTION: Increase of flexture in the shaft tip part is effective in obtaining a blow angle advantageous to a carry, so that flexural rigidity in the tip part is set to be 2×10<6> kgf.mm<2> or less. As flexural rigidity is set to be 8×10<6> kgf.mm<2> or more in the position separated from the tip part, by 900 mm or more, flexture of the shaft in returning is suppressed and a constant swing can be performed. Desirably, torsional rigidity of the shaft tip part is set to be 1×10<6> kgf.mm<2> or more in the area within 200 mm range from the tip part, while the flexural rigidity of the shaft is set to be 2×10<6> kgf.mm<2> or less in the 200 mm range from the tip.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention improves the blow angle and directionality immediately before impact by setting the length of a golf club, the neck length of a golf head, the bending rigidity and the torsional rigidity of the tip of a golf shaft. The present invention relates to a golf shaft for increasing the flight distance and a golf club equipped with the golf shaft.

[0002]

2. Description of the Related Art Conventionally, golf shafts (hereinafter abbreviated as shafts) mounted on golf clubs having a diameter of 44 inches or more are often light weights of 60 g or less. In order to protect the tip of the shaft to be joined from breakage, it is necessary to design the shaft to have high strength. Therefore, the shaft is often reinforced with high-strength and high-elasticity impact-resistant carbon fibers. Therefore, in a golf club which is said to be 44 inches or longer, the bending rigidity of the tip portion of the shaft is high, and the other bending rigidities are reduced, so that the launch angle of the ball at the time of hitting the ball is increased. Further, in the case of these lightweight shafts, the torsional rigidity has been reduced in terms of weight reduction and the like. Further, in the case of the conventional head, there is a drawback that when the neck length is increased, the amount of bending at the tip of the shaft is reduced, and when the neck length is shortened, the amount of twist of the shaft is increased.

[0003]

In a conventional shaft, there is a tendency that bending rigidity is increased in order to maintain strength of a tip portion. For this reason, the tip of the shaft hardly bends, and among the functions of the shaft, the effect of increasing the ball projection angle when hitting a ball cannot be obtained. Also, if the bending stiffness other than the tip of the shaft is lowered to increase the pop-out angle, the amount of deflection of the shaft at the time of turning back at the top during a swing increases, making it difficult to take timing, making it more difficult than usual. Also, it is necessary to reduce the amount of bending by lowering the speed at the time of turning back, and it is necessary to make it slower than a normal swing, which makes it difficult for the golfer to perform the original swing. In addition, a shaft having a low bending rigidity has a low torsional rigidity, so that the direction of the head immediately before hitting the ball is not determined, and as a result, the golf club has poor directivity.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a shaft using fiber reinforced plastics, wherein a shaft having a bending rigidity and a torsional rigidity at a tip portion and a proximal side of the shaft and a head having a neck length of 50 are provided. A golf club characterized by having a diameter of less than millimeters. That is, in the shaft or golf club of the present invention, the bending rigidity at the hand side is set slightly higher than that of the conventional shaft, the bending rigidity at the distal end is set lower, and the torsional rigidity is increased over the entire shaft. This solves the above problem.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventor measured the movements of a head and a ball before and after impact of many golfers including professional golfers using high-speed video. As a result, even at the same head speed, there was a great difference in flight distance, and it was found that the cause was a blow angle. That is, Table 1 shows the measurement results of two professional golfers (A professional and B professional) having substantially the same head speed.

[0006]

[Table 1]

From this result, it can be seen that the initial ball speed is different even at substantially the same head speed, and this difference in initial ball speed directly affects the flight distance. The blow angle can be raised as a factor that determines the ball initial velocity. The blow angle 5 is an angle between the moving direction of the head 2 and the horizontal line immediately before the collision of the head 2 and the ball 4, and is shown in FIG. As shown, the case where the head 2 moves upward is defined as positive, and this case is called upper blow. Conversely, a case where the head 2 moves downward from above as shown in FIG. 1B is regarded as negative, and this case is called a down blow. FIG. 1C shows a schematic view of the blow angle 5.

As described above, the repulsion ratio (= ball initial speed / head speed) of the B-pro hit by the upper blow is larger than that of the A-pro hit by the down blow, and as a result, the flight distance is longer. . FIG. 2 shows a dynamic model of an oblique collision between a head and a ball. From this figure, the force component in the direction perpendicular to the face 2C that affects the ball initial velocity is more likely to be caused by the upper blow ((A) of FIG. 2) than the head 2 hitting the ball 4 with the down blow ((B) of FIG. 2). It can be seen that the collision with)) is larger. In other words, even if the ball hits the ball at the same head speed, it can be said that hitting with the upper blow increases the initial ball speed and increases the flight distance as compared with hitting with the down blow.

In order to obtain a blow angle that is advantageous for the flight distance, it is effective to increase the bending of the tip, which is not so much bent in the conventional shaft. It is desirable to set it to × 10 ⁶ kgf · mm ² or less. In addition, in order to keep the timing of the swing constant, the bending rigidity on the grip side has an effect. FIGS. 3A and 3B show time-series data of bending strain at a shaft position (lower part of the grip) of 835 mm from the heel end surface of the golf club during a swing. 3 (A) and 3 (B), the bending strain becomes maximum at the time of the backswing to the backswing return (top return). That is,
The bending rigidity on the grip side of the shaft is the most important in determining the timing of turning back the swing, and the bending rigidity at a position 900 mm or more from the tip is 8 × 10 ⁶ kgf.
When the diameter is not less than mm ² , as shown in FIG. 3 (A), the bending of the turning shaft is suppressed as in the present invention, and a constant swing can be performed. In particular, the directionality is remarkably improved by setting the torsional rigidity of the shaft tip to 1 × 10 ⁶ kgf · mm ² or more within a range of 200 mm from the tip.

The bending rigidity of the shaft is 2 × 10 ⁶ kgf ·
mm ² or less, 90 mm from the tip that affects flex
By setting it to 8 × 10 ⁶ kgf · mm ² or more in the range of 0 mm or more, and by setting the neck length of the head to 50 mm or less, the blow angle at the time of hitting the ball, that is, The speed is increased, and as a result, the flight distance is increased. Further, it can be seen from Equation 1 that θ (t) representing the return of the head is ultimately related to the torsional spring constant of the shaft, that is, the torsional rigidity of the shaft. In particular, by increasing the torsional rigidity of the tip of the shaft, the return of the head is improved. That is, by setting the torsional stiffness to 1 × 10 ⁶ kgf · mm ² or more within a range of 200 mm from the tip of the shaft that affects the head return, the head return immediately before hitting the ball is improved, Can be better.

[0011]

(Equation 1)

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described. A shaft 1 made of fiber reinforced plastics has a bending rigidity of 2 × 10 ⁶ kgf · mm within a range of 200 mm from the tip 1A. ² or less and tip 1A
The bending stiffness at a position of 900 mm or more is 8 × 10 ⁶
a shaft 1 characterized by being at least kgf · mm ²
It is.

As another embodiment of the present invention, in a golf club 3 equipped with a shaft 1 made of fiber reinforced plastics, the bending rigidity of the shaft 1 is 2 × 10 ⁶ within a range of 200 mm from the tip 1A. kgf ・ mm ²
A shaft 1 having a bending rigidity of 8 × 10 ⁶ kgf · mm ² or more at a position of 900 mm or more from the tip 1A is mounted on a head 2 having a neck length of 50 mm or less. Golf club 3.

Another embodiment of the present invention is a shaft 1 made of fiber reinforced plastics, wherein the torsional rigidity of the shaft 1 is within a range of 200 mm from the tip 1A.
× 10 ⁶ kgf · mm ² or more, and the bending rigidity of the shaft 1 is 2 × 10 ^{6 in} the range of 200 mm from the tip 1A.
a shaft 1 characterized by being equal to or less than kgf · mm ²
It is.

Another embodiment of the present invention is a golf club 3 equipped with a shaft 1 made of fiber reinforced plastics.
A is 1 × 10 ⁶ kgf · mm ² or more in the range from A to 200 mm, and the bending rigidity of the shaft 1 is ² mm from the tip 1A.
A golf club 3 characterized in that a shaft 1 having a neck length of 50 mm or less is mounted on a shaft 1 having a diameter of 2 × 10 ⁶ kgf · mm ² or less in a range of 00 mm.

Another embodiment of the present invention is a shaft 1 made of fiber reinforced plastics, wherein the torsional rigidity of the shaft 1 is within a range of 200 mm from the tip 1A.
× 10 ⁶ kgf · mm ² or more, and the bending rigidity of the shaft 1 is 2 × 10 ^{6 in} the range of 200 mm from the tip 1A.
kgf · mm ² or less, and 900 from the tip 1A
The bending stiffness at a position of at least 8 mm is 8 × 10 ⁶ kgf
mm ¹ or more.

As another embodiment of the present invention, in a golf club 3 equipped with a shaft 1 made of fiber reinforced plastics, the torsional rigidity of the shaft 1
A is 1 × 10 ⁶ kgf · mm ² or more in the range from A to 200 mm, and the bending rigidity of the shaft 1 is ² mm from the tip 1A.
A shaft 1 having a neck length of 50 mm is 2 × 10 ⁶ kgf · mm ² or less in a range of 00 mm, and has a bending rigidity of 8 × 10 ⁶ kgf · mm ² or more at positions 900 mm or more from the tip 1A. A golf club 3 mounted on the following head 2.

Another embodiment of the present invention is a shaft 1 made of fiber reinforced plastics, which has a bending rigidity at a position 200 mm from the tip 1A of the shaft 1.
1/4 of the bending stiffness at a position 900 mm from the tip 1A
A shaft 1 characterized by the following.

As another embodiment of the present invention, in a golf club 3 equipped with a shaft 1 made of fiber reinforced plastics, the tip 1A of the shaft 1 to 200
The bending rigidity at the position of 1 mm is 900 mm from the tip 1A.
The golf club 3 is characterized in that the shaft 1 having a bending rigidity of 1/4 or less at the position of the position 1 is mounted on the head 2 having a neck length of 50 mm or less.

Next, FIG. 4 shows the bending rigidity distribution of the shaft of the present invention, and FIG. 5 shows the torsional rigidity distribution of the shaft of the present invention. FIG. 6 shows the distribution of bending stiffness of the conventional shaft, and FIG. 7 shows the distribution of torsional stiffness of the conventional shaft.

As measurement data on the bending stiffness distribution and the torsional stiffness distribution of the shaft, a comparative test was conducted using the shaft of the present invention and a conventionally known shaft. A prepreg using carbon fiber XN-05 (tensile modulus of elasticity 5000 kgf / mm ² ) made by Nippon Graphite Fiber is used, and carbon fiber T700 manufactured by Toray Industries, Ltd. (tensile modulus of elasticity 24000 kgf) is used for the reinforcing layer of the conventional shaft. / Mm ² ). In the shaft of the present invention, a carbon fiber M50J manufactured by Toray Industries, Inc. (tensile modulus of elasticity: 50,000) is provided in the bias layer (fiber distribution angle ± 40 °).
kgf / mm ² ) and carbon fiber M30S manufactured by Toray Industries, Inc. (tensile elastic modulus 30,000 kg)
f / mm ² ). In the shaft of the present invention and the conventional shaft, a prepreg using carbon fibers (tensile modulus of elasticity of 29,000 kgf / mm ² ) was used for the straight layer (the fiber laying angle ± 0 ° to ± 5 °). In the present invention, the bending rigidity on the grip side is increased by adjusting the shape of the mandrel, for example, by increasing the outer diameter on the grip side (butt side) or increasing the wall thickness of the shaft. In addition, the torsional rigidity of the distal end can be improved without increasing the bending rigidity by using a highly elastic carbon fiber for the bias layer at the distal end of the shaft.

Table 2 shows the specifications of the golf club.
Shown in As shown in FIG. 9, the club length is from the grip end 6 to the heel end surface 2A of the head 2, and the neck length is from the neck end surface 2B of the head 2 to the heel end surface 2A.

[0023]

[Table 2]

As described above, in the shaft 1 of the present invention, the bending rigidity of the shaft 1 is set to 200 mm from the tip 1A.
2 × 10 ⁶ kgf · mm ² or less in the range of
8 × 10 ⁶ kgf · mm from A to 900mm or more
² or more, and the torsional rigidity was 1 × 10 ⁶ kgf · mm ² or more within a range of 200 mm from the tip 1A. And
Using a golf club 3 of the present invention in which the neck length of the head 2 was 50 mm or less and a conventional product, measurement was performed at a head speed of 40 m / s corresponding to the head speed of an average golfer. In the measurement, a high-speed camera was installed at a position perpendicular to the ball flying direction, and the head speed, blow angle, ball speed, and ball launch angle were analyzed by the high-speed camera.

As for the directionality, that is, the return of the head 2, as shown in FIGS. 8 and 9, a high-speed video camera 7 is installed on the upper surface, and the face angle immediately before the golf head 1 collides with the ball 4 is determined. The changes were analyzed. The torsional strain gauge 8 was attached to the shaft, and the torsional angle of the shaft was measured. The golf club used in the experiment had a length of 45 inches and a neck length of 50 mm.

The experimental results of the golf club according to the present invention are as follows:
As shown in Table 3, although the head speed was substantially equal, the blow angle increased, and as a result, the initial speed of the ball increased.

[0027]

[Table 3]

Further, a strain gauge was attached to the shaft, and the bending of the shaft immediately before impact during the swing was measured.

As the physical quantity, the distribution of the time change rate (dK / dt) of the curvature in the longitudinal direction of the shaft immediately before the impact (from 5 ms before the impact to immediately before the impact) was observed. That is,
FIG. 10 (A) shows the distribution for the product of the present invention, and FIG. 10 (B) shows the distribution for the conventional shaft. This shows that the product of the present invention has a larger tip and a larger curvature than the conventional product. As a result, the blow angle became larger, resulting in an upper blow, and the initial ball speed increased.
Thus, it can be seen that dK / dt from the tip to 200 mm has a large effect on the blow angle, and is further related to the neck length. If the neck length is not less than 50 mm, the rigidity of the neck affects dK / dt, and sufficient bending of the distal end cannot be obtained even if the bending rigidity of the distal end of the shaft is reduced.

FIGS. 12A and 12B show time-series data of the product of the present invention and the conventional product immediately before the impact of the torsion angle of the shaft. These results show that the return of the head of the product of the present invention is improved.

[0031]

According to the present invention, the bending rigidity at the distal end of the shaft is reduced and the bending at the distal end of the shaft immediately before impact is increased in a shaft capable of performing a constant swing without setting the bending rigidity on the hand side low. Increasing the blow angle allows the head and the ball to collide with the upper blow, thereby increasing the flight distance. Also, by improving the torsional rigidity of the tip of the shaft, the return of the head immediately before impact is improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a blow angle.

FIG. 2 is an explanatory diagram showing a dynamic model of an oblique collision between a golf head and a ball.

FIG. 3 is a graph showing a time series of bending strain of a shaft during a swing.

FIG. 4 is a graph showing measured values of distribution of bending stiffness of a shaft according to the present invention.

FIG. 5 is a graph showing measured values of torsional rigidity distribution of a shaft according to the present invention.

FIG. 6 is a graph showing measured values of distribution of bending stiffness of a conventional shaft.

FIG. 7 is a graph showing measured values of a torsional rigidity distribution of a conventional shaft.

FIG. 8 is an explanatory diagram showing a method of measuring the return of the head when hitting a ball.

FIG. 9 is an explanatory view showing a method of measuring the return of the head when hitting a ball.

FIG. 10 is a graph showing the temporal change rate of the curvature in the longitudinal direction of the shaft immediately before impact of the product of the present invention.

FIG. 11 is a graph showing a temporal change rate of a curvature in a longitudinal direction of a shaft immediately before impact of a conventional product.

12 (A) and 12 (B) are graphs showing the time series of the torsion angle of the shaft of the present invention and the shaft of the conventional shaft immediately before impact.

[Explanation of symbols]

 Reference Signs List 1 shaft 1A tip 2 golf head 2A heel end 2B neck end 2C face 3 golf club 4 ball 5 blow angle 6 grip end 7 high speed video camera 8 torsion strain gauge

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoshihiro Fujikawa 1-12-35 Minami Kohoku, Suminoe-ku, Osaka-shi, Osaka

Claims (8)

[Claims] 1. A golf shaft made of fiber reinforced plastics, wherein the golf shaft has a bending stiffness of 2 × 10 ⁶ kgf · mm ² or less within a range of 200 mm from the tip and 900 mm or more from the tip. The bending stiffness at the position (1) is 8 × 10 ⁶ kgf · mm ² or more. 2. A golf club equipped with the golf shaft according to claim 1, wherein the golf shaft is attached to a golf club head having a neck length of 50 mm or less. 3. A golf shaft made of fiber reinforced plastics, wherein the golf shaft has a torsional rigidity of 1 × 10 ⁶ kgf · mm ² or more within a range of 200 mm from the tip end, and the golf shaft has a flexural rigidity. , 200 from the tip
A golf shaft having a size of 2 × 10 ⁶ kgf · mm ² or less in a range of mm. 4. A golf club equipped with the golf shaft according to claim 3, wherein the golf shaft is mounted on a golf club head having a neck length of 50 mm or less. 5. A golf shaft made of fiber reinforced plastics, wherein the golf shaft has a torsional stiffness of 1 × 10 ⁶ kgf · mm ² or more within a range of 200 mm from the tip end, and the golf shaft has a flexural stiffness. , 200 from the tip
A golf shaft characterized by being 2 × 10 ⁶ kgf · mm ² or less in a range of mm and having a bending rigidity of 8 × 10 ⁶ kgf · mm ² or more at positions 900 mm or more from the tip. 6. A golf club equipped with the golf shaft according to claim 5, wherein the golf shaft is mounted on a golf club head having a neck length of 50 mm or less. 7. A golf shaft made of fiber reinforced plastics, wherein the golf shaft is 200 mm from the tip of the golf shaft.
The bending rigidity at the position of (1) is not more than 1/4 of the bending rigidity at the position of 900 mm from the tip. 8. A golf club equipped with the golf shaft according to claim 7, wherein the golf shaft is attached to a golf club head having a neck length of 50 mm or less.