JP2000254264A - Golf club shaft and driver using the same - Google Patents

Abstract

(57) [Problem] To provide a golf club shaft capable of easily swinging, increasing the flight distance of the ball, and accurately flying the ball, and a driver using the shaft. SOLUTION: A shaft 2 has a tip close to a head 4;
And a rear end near the grip 6. This shaft 2
Has a peak near the center and a valley bottom between the peak and the grip center of the grip. The bending stiffness value gradually decreases from the peak portion to the valley bottom, and the bending stiffness value gradually increases from the valley bottom to the grip center position.
The bending rigidity value at the grip center position is the maximum.

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 and a driver using the golf club shaft, and more particularly to a golf club shaft and a driver molded from a fiber reinforced resin. is there.

[0002]

2. Description of the Related Art In recent years, fiber reinforced resin shafts have been widely used in golf clubs. By using this shaft, the weight of the golf club can be reduced, and the degree of freedom in design such as a bending rigidity value and a torsional rigidity value can be increased. For example, when a so-called front-end shaft, whose tip is relatively flexible, is used, the golf club head speed is increased and the ball tends to have a high trajectory, so that a golf club suitable for a weak golfer can be obtained. On the other hand, if a shaft with a so-called hand tone, in which the front end is relatively hard to bend and the rear end is soft, is used, the left and right movement of the ball in the flight direction is reduced,
A golf club suitable for a hard hitter is obtained. Of course, what shaft a golfer prefers depends not only on the power of the golfer, but also on the swing style,
It is affected by various factors such as matching with the ball.

[0003] In a normal shaft, the bending rigidity gradually increases from the front end on the head mounting side to the rear end on the grip side. This is based on the bending rigidity value of a steel shaft before the fiber reinforced resin was adopted. Today, as the fiber reinforced resin is used and the degree of freedom in designing the bending stiffness value is improved as described above, it is desired to improve the distribution of the bending stiffness value.

Japanese Unexamined Patent Publication No. 7-21658 discloses a shaft in which the distribution of bending stiffness is devised. This shaft is made of fiber reinforced resin and has a flexible portion near the center.

[0005]

By the way, a golfer usually moves the head from the address position in the direction opposite to the hitting direction, turns back at the top position, swings the head down, and hits the ball. In this series of swing operations, turning back at the top position is extremely important. At the top position, the golfer senses the deflection of the shaft, the position of the head, the orientation of the head, etc. with the grip,
Move to the downswing with the timing of turning back.
The ease with which the timing of turning back is dominant governs the ease of swing of the golf club. In other words, the golfer can hit the ball with a more accurate face orientation and with a higher head speed as the club with the easier switching timing.

However, in the above-described shaft having a flexible portion near the center, the difference in bending rigidity between the flexible portion and the portion other than the flexible portion is too large, and the bending rigidity value is extremely large at the boundary between the two. Because it changes, it is difficult for golfers to take the timing of switching back. Therefore, this shaft is difficult for the golfer to swing, the head speed cannot be sufficiently increased, and the direction of the ball tends to fluctuate.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is a golf club shaft capable of easily swinging, increasing the flight distance of the ball, and accurately flying the ball, and a driver using the shaft. It is an object to provide

[0008]

In order to solve the above-mentioned problems, the present invention includes a peak portion (P3) having a large bending stiffness value near a center portion, and the peak portion (P3) and the grip portion have a large rigidity value. A valley bottom (P2) having a small bending stiffness value is provided between the center of the grip (P1) and the peak (P1).
The bending stiffness value gradually decreases from 3) to the valley bottom (P2), and the gripping center position (P
The flexural rigidity value gradually increases toward 1), and a golf club shaft having the maximum flexural rigidity value at the grip center position (P1) is provided.

The grip center position of the grip portion is a position approximately 115 mm from the rear end of the shaft. That is, the grip portion is usually 250 mm to 300 mm, and the user grips the grip portion with both hands to hit. When gripping the grip part, the center position in the longitudinal direction of the shaft is 100 m from the rear end.
m to 130 mm, so that the grip center position is about 11
5 mm.

In the present invention, attention is paid to the bending stiffness from the grip center position (P1) to the valley bottom (P2) and the peak (P3). Note that the rigidity is not limited in the range from the grip center position (P1) to the rear end side since the influence of ease of swing and timing is small, but the rigidity is not limited. Preferably, the rigidity is substantially the same as that described above, or the rigidity is such that the increase in rigidity applied from the bottom of the valley to the center of the grip is directly connected to the rear end.

As described above, the golf club shaft of the present invention has the peak portion (P3) and the valley bottom portion (P2), and the bending rigidity value does not change extremely. The golf club used is easy for golfers to take timing and swings easily. Therefore, the head speed is increased, and the ball can be hit accurately. In the present specification, a state where there is no portion where the difference between the bending rigidity values of two places 100 cm apart in the golf club shaft is 2.5 N · m2 or more is defined as “the bending rigidity value gradually changes”. Is called.

In the present invention, the bending stiffness value (M3) of the peak portion (P3) is determined by the grip center position (P
Value (M3 / M1) divided by bending stiffness value (M1) of 1)
Is preferably 0.80 or more and 0.95 or less, particularly preferably 0.85 or more and 0.95 or less. If this value is less than the above range, the golf club shaft may be excessively bent, impairing the ease of swinging, and may be inferior in durability, increasing the risk of breakage during the swing. vice versa,
If this value exceeds the above range, the bending stiffness value of the peak portion (P3) will not be sufficiently lower than the bending stiffness value of the grip center position (P1), and an appropriate deflection will not be obtained. Sometimes it feels hard and the ease of swing is impaired.

In the present invention, the bending stiffness value (M2) of the valley bottom (P2) is changed to the bending stiffness value (M3) of the peak portion (P3).
(M2 / M3) is preferably 0.85 or more and 0.95 or less, particularly preferably 0.90 or more and 0.95 or less. If this value is less than the above range, the golf club shaft may be excessively bent, impairing the ease of swinging, and may be inferior in durability, increasing the risk of breakage during the swing. Conversely, if this value exceeds the above range, the bending stiffness value of the valley bottom (P2) will not be sufficiently low, an appropriate bending will not be obtained, and the golfer will feel stiff during the swing and lose ease of swinging. May be lost.

In the present invention, the bending stiffness value (M2) at the valley bottom (P2) is determined by the bending stiffness value (M2) at the center position (P1) of the grip.
The value (M2 / M1) divided by 1) is 0.65 or more and 0.8
0 or less, preferably 0.65 or more and 0.70 or less. If this value is less than the above range, the golf club shaft may be excessively bent, impairing the swingability, and may be inferior in durability, increasing the risk of breakage during the swing. Conversely, if this value exceeds the above range, the bending stiffness value at the bottom of the valley (P2) will be
The flexural rigidity value is not sufficiently lower than the flexural rigidity value of 1), an appropriate flexure cannot be obtained, and the golfer may feel hard during the swing and lose ease of swing.

In the present invention, the peak portion (P
The value obtained by dividing the distance to 3) by the distance from the tip Y to the grip center position (P1) (hereinafter, this value is also referred to as “P3 position”) is preferably 0.35 or more and 0.55 or less. , 0.40 or more and 0.50 or less. If this value is less than the above range, the bending stiffness value near the tip will inevitably increase, and if the bending stiffness value near the tip is forcibly reduced, the change in bending stiffness value will be extreme. In some cases, the golf club shaft is not practical because of its strength design. Conversely, if this value exceeds the above range, the position of the valley bottom (P2) is necessarily closer to the grip center position (P1), and the effect of improving the ease of swing cannot be obtained. The bending stiffness value of (P2) may not be sufficiently lower than the bending stiffness value of the grip center position (P1).

In the present invention, from the tip Y to the valley bottom (P
The value obtained by dividing the distance to 2) by the distance from the tip Y to the grip center position (P1) (hereinafter, this value is also referred to as “P2 position”) is preferably 0.50 or more and 0.70 or less. , 0.55 or more and 0.65 or less. If this value is less than the above range, the peak portion (P3) is inevitably closer to the front end, and the bending rigidity value near the front end is increased. Also, if the bending rigidity value near the front end is forcibly reduced, the bending will occur. Since the change in the rigidity value becomes extreme, the shaft may not be a golf club shaft that is practical in terms of strength design. Conversely, if this value exceeds the above range, the position of the valley bottom (P2) is closer to the grip center position (P1), and the effect of improving the ease of swing cannot be obtained.
The bending stiffness value of the valley bottom (P2) may not be sufficiently lower than the bending stiffness value of the grip center position (P1).

The golf club shaft of the present invention is particularly suitable for a driver (wood's No. 1 club) requiring flight distance performance. The overall length (distance from the front end to the rear end) of the golf club shaft used for the driver is usually 1092 mm or more and 1270 mm or less.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a front view showing a driver using a golf club shaft 2 according to an embodiment of the present invention, together with a head 4 and a grip 6. The outer diameter and the inner diameter of the shaft 2 are reduced from the rear end X to the front end Y. The head 4 is inserted into the hosel 8 with the tip Y of the shaft 2 inserted therein.
It is fixed to the shaft 2. The rear end X of the shaft 2 is inserted into the inner periphery of the grip 6. The total length of the shaft 2 (indicated by a double arrow L in FIG. 1) is 1
It is 125 mm.

FIG. 2 is a graph schematically showing the distribution of the bending rigidity of the shaft 2 of FIG. This shaft 2
Has a peak portion (P3) having a large bending stiffness value near the center in the longitudinal direction, and a valley bottom (B) having a small bending stiffness value between the peak portion (P3) and the gripping center position (P1). P2). In the present embodiment, the gripping center position (P1) is a position 115 mm from the rear end X of the shaft 2. The bending rigidity gradually decreases from the peak (P3) to the valley bottom (P2). Further, the bending stiffness value gradually increases from the valley bottom (P2) to the grip center position (P1). Further, the peak portion (P
From 3), the bending stiffness value gradually decreases toward the front end Y, but the bending stiffness value becomes a little closer to the rear end than the front end Y, and the bending stiffness value slightly increases from here toward the front end. I have. The bending rigidity value at the grip center position (P1) is the maximum. That is, the peak portion (P
The bending stiffness value of 3) is smaller than the bending stiffness value of the grip center position (P1).

FIG. 3 is a developed view schematically showing types of prepregs 10, 12, 14, and 16 used for the shaft 2 of FIG. One prepreg 10, one second prepreg 12, three third prepregs 14, and two fourth prepregs 16 shown in FIG. 1 are wound around a mandrel (not shown). , 1
The shaft 2 is molded by heating and curing the synthetic resin in 2, 14, and 16 and pulling out the mandrel. Each of the prepregs 10, 12, 14, 16 has a reinforcing fiber 18 in a specific direction. As the reinforcing fiber 18 to be used, for example, carbon fiber, glass fiber, aramid fiber, metal fiber and the like can be mentioned, and usually, carbon fiber is used.

First prepreg 10 and second prepreg 1
2 is also referred to as an oblique layer, and the angle between the fiber direction and the longitudinal direction of the shaft 2 is generally 45 ° ± 10 °. By changing the angle and the number of windings, the torsional rigidity value of the shaft 2 can be mainly set. First prepreg 10
And the fiber direction of the second prepreg 12 are oblique directions opposite to each other with respect to the longitudinal direction of the shaft 2.

The third prepreg 14 is also referred to as a straight layer, and its fiber direction is substantially coincident with the longitudinal direction of the shaft 2. By changing the elastic modulus and strength of the reinforcing fibers 18 and the number of windings of the third prepreg 14, the bending rigidity value of the shaft 2 can be mainly set.

The fourth prepreg 16 is also called a partial reinforcing layer, and is laminated only on a part of the entire length of the shaft 2. By changing the number of the fourth prepregs 16, the elastic modulus of the reinforcing fibers 18, and the like, the distribution of the bending stiffness value mainly in the length direction can be set. The fourth prepreg 16 has a trapezoidal quadrangular shape, and the position of the vertex 20 at the position where the width is maximum is the peak portion (P
The position substantially coincides with the position 3), and the position of the vertex 22 closest to the rear end substantially coincides with the position of the valley bottom (P2).

[0024]

EXAMPLE Hereinafter, an experiment 1 performed according to an example of the present invention will be described.
And the effect of the present invention based on Experiment 2.

<Experiment 1 Experiment with Pre-Adjusted Shaft> [Example 1] Example 1 using a prepreg as illustrated in FIG. 3 and having a total length of 1125 mm and a weight of 80.6 g.
Was manufactured. The flex of this shaft is
As shown in Table 1 below, the forward formula was 87 mm, the reverse formula was 88 mm, and the pre-tone rate was 50.3%. Here, the forward flex is an index of hardness on the hand side of the shaft, and as shown in FIG. 4, a position 953 mm from the front end is set as a fulcrum A, and 140 mm closer to the rear end from the fulcrum A.
Is a fixed point B, a 2.7 kg weight W1 is hung at a position 129 mm from the tip Y, and the amount of deflection of the tip Y is measured. In addition, the inverse flex is an index of the hardness of the tip end side of the shaft, and as shown in FIG.
A position 140 mm closer to the tip from the fulcrum C is defined as a fixed point D, and a 1.3 kg weight W2 is located 928 mm from the tip Y.
And the amount of deflection of the rear end X is measured. The pre-tone rate is derived by the following equation (reverse flex / (forward flex + reverse flex)) × 100.

The distribution of the bending stiffness of the shaft was measured. The results are shown in FIGS. As shown in FIG.
The shaft 2 is horizontally arranged on the support tools 50 and 51 installed at both ends with a distance of 0 mm, and the indenter 52 is set upward with the center at the center position of the span 200 mm (that is, 100 mm from the support tools 50 and 51). 5mm / 5min
At the same speed, and the applied load at that time is 2
The test was terminated when the weight reached 0 kg, and the deformation amount x (mm) of the shaft 2 at that time was measured as shown in FIG. The bending stiffness value was determined from the amount of deformation x (mm) by the following equation. The measurement of this bending stiffness value is P1, P
2 and P3, and the center position of the indenter 52 is P1, P
2 and P3. The support 50,
Reference numeral 51 denotes a shaft supporting surface having an arc shape of 12.5 mm, and a shaft contact surface of the indenter 52 having a radius of 75 mm.
Arc surface.

EI (flexural rigidity value) = (V × S3) / (48 × δ) δ (spring constant): (x / 100) × 5 (mm) V (load): 20 kg S (span): 200 mm

As a result of the above measurement, the P3 position of the shaft was 0.48, the P2 position was 0.64, and M3 / M1 was 0.8.
2, M2 / M3 was 0.93 and M2 / M1 was 0.76.

Example 2, Comparative Example 1, and Comparative Example 2 The shafts of Example 2, Comparative Example 1, and Comparative Example 2 were obtained in the same manner as in Example 1, except that the layer structure of the prepreg was changed. . Weight, flex, pre-strain,
P3 position, P2 position, M3 / M1, M2 / M3 and M2
/ M1 is shown in Table 1 below. FIG. 7 shows the measurement results of the distribution of the bending stiffness values. Comparative Example 1
The shaft of Comparative Example 2 is different from the shafts of Example 1 and Example 2 in that M3 / M2 is 1.00 or more.

[Conventional Example 1] A commercially available shaft is prepared,
Conventional Example 1 was used. The weight, flex and pre-strain of this shaft are shown in Table 1 below. FIG. 7 shows the measurement results of the distribution of the bending stiffness values. FIG.
As is clear from FIG. 5, this shaft has a peak portion (P3).
And no valley bottom (P2).

[0031]

[Table 1]

[Evaluation of Flight Distance Performance] Five top amateurs A to E who prefer a pre-tuned shaft were used as testers, and the shafts of Examples 1, 2, Comparative Examples 1, 2 and a conventional example were used. The ball was tested with a driver equipped with. For all drivers, specifications other than the shaft, such as the head and grip, have been unified. Then, a head speed, a ball initial speed, a flight distance, and a left-right deviation were measured. The results are shown in Table 2 below. The left and right misalignment in Table 2 refers to a distance at which the ball drop point is displaced from the target direction. The case where the ball deviates to the left from the target is represented by “−”, and the case where the ball is displaced to the right is represented by “+”. ing.

[0033]

[Table 2]

In Table 2, the drivers equipped with the shafts of Examples 1 and 2 are Comparative Examples 1 and 2
In addition, the flight distance is longer than that of the driver equipped with the shaft of Conventional Example 1. Further, the absolute value of the lateral displacement is smaller in the driver equipped with the shafts of Example 1 and Example 2 than the driver equipped with the shafts of Comparative Example 1 and Comparative Example 2. From this, it was confirmed that the shaft of the present invention was excellent in flight distance performance and directionality.

[Evaluation of Sensitivity] Each tester in the flight distance performance evaluation described above was evaluated for satisfaction, hardness and ease of swing.
The evaluation was made on a scale of 1 to 5. Regarding the degree of satisfaction, the most dissatisfied was set to "1" and the most satisfactory was set to "5". Regarding the hardness, "1" was set for a sample that was too soft, "5" was set for a sample that was too hard, and "3" was set for a sample that was just right. Regarding the ease of swing, the one that is hardest to swing is “1”, and the one that is easy to swing is “5”. The results are shown in Table 3 below.

[0036]

[Table 3]

According to the evaluation results shown in Table 3, the driver equipped with the shafts of Examples 1 and 2 was more satisfactory than the drivers equipped with the shafts of Comparative Example 1, Comparative Example 2 and Conventional Example 1. It was confirmed that all of the hardness and the ease of swing were excellent.

<Experiment 2 Experiment Using Hand Tone Shaft> [Example 3, Example 4, Comparative Example 3 and Comparative Example 4] Except for changing the layer configuration of the prepreg, the same procedure as in Example 1 was repeated.
The shafts of Example 3, Example 4, Comparative Example 3 and Comparative Example 4 were obtained. The weight, flex, pre-tone, P3 position, P2 position, M3 / M1, M2 / M3 and M2 / M1 of these shafts are shown in Table 4 below. FIG. 8 shows the measurement results of the distribution of the bending stiffness values. M3 / M2 of the shafts of Comparative Examples 3 and 4 was 1.00.
The above is different from the shafts of the third and fourth embodiments.

[Conventional example 2] A commercially available shaft is prepared,
Conventional Example 2 was set. The weight, flex, and pre-strain of this shaft are shown in Table 4 below. FIG. 8 shows the measurement results of the distribution of the bending stiffness values. FIG.
As is clear from FIG. 5, this shaft has a peak portion (P3).
And no valley bottom (P2).

[0040]

[Table 4]

[Evaluation of Flight Distance Performance and Sensitivity Evaluation] Evaluation of flight distance performance and evaluation of flight distance performance were performed in the same manner as in Experiment 1 described above, except that five top amateurs from F to J who preferred a hand-held shaft were used as testers. Kansei evaluation was performed. The results are shown in Tables 5 and 6 below.

[0042]

[Table 5]

[0043]

[Table 6]

In Table 5, the drivers equipped with the shafts of Examples 3 and 4 are Comparative Examples 3 and 4.
In addition, the flight distance is longer than that of the driver equipped with the shaft of Conventional Example 2. In addition, the absolute value of the lateral displacement is smaller in the driver equipped with the shafts of Examples 3 and 4 than the driver equipped with the shafts of Comparative Examples 3 and 4. From this, it was confirmed that the shaft of the present invention was excellent in flight distance performance and directionality.

Also, from the evaluation results in Table 6, the drivers equipped with the shafts of Examples 3 and 4 are more satisfactory than the drivers equipped with the shafts of Comparative Examples 3, 4 and Conventional Example 2. It was confirmed that the degree, hardness and ease of swing were all excellent. In addition, the driver of Comparative Example 4 was damaged when testers G and J were tested. This is because the strength is insufficient.

[0046]

As is apparent from the above description, according to the present invention, it is possible to obtain a golf club shaft which can be easily swung, can increase the ball's flight distance, and can accurately fly the ball. it can. The shaft of the present invention
In particular, it is suitably used for a driver requiring flight distance performance.

[Brief description of the drawings]

FIG. 1 is a front view showing a driver using a golf club shaft according to an embodiment of the present invention, together with a head and a grip.

FIG. 2 is a graph schematically showing a distribution of bending stiffness values of the shaft of FIG. 1;

FIG. 3 is a developed view schematically showing types of prepregs used for the shaft of FIG. 1;

FIG. 4 is a schematic front view for explaining a state of measurement of a forward flex.

FIG. 5 is a schematic front view for explaining a state of measurement of an inverse flex.

FIG. 6A is a drawing showing a method of measuring a bending rigidity value,
(B) is a diagram showing the relationship between the load and the amount of deformation.

FIG. 7 is a graph showing a measurement result of a distribution of a bending stiffness value.

FIG. 8 is a graph showing a measurement result of a distribution of a bending stiffness value.

[Explanation of symbols]

 P1 Grip center position of grip portion P2 Valley bottom P3 Peak portion 2 Shaft 4 Head 6 Grip 8 Hosel 10 First prepreg 12 Second prepreg 14 Third prepreg 16 Fourth prepreg 18 Reinforcing fiber

Claims (6)

[Claims] A peak portion (P3) having a large bending stiffness value is provided near a center portion, and a small bending stiffness value is provided between the peak portion (P3) and a grip center position (P1) in a grip portion. It has a valley bottom (P2), and the bending stiffness value gradually decreases from the peak (P3) to the valley bottom (P2), and the bending stiffness value from the valley bottom (P2) to the gripping center position (P1). Is gradually increased, and the bending rigidity value at the grip center position (P1) is the maximum. 2. The bending rigidity value (M) of the peak portion (P3).
The golf club shaft according to claim 1, wherein a value (M3 / M1) obtained by dividing 3) by a bending rigidity value (M1) at the grip center position (P1) is 0.80 or more and 0.95 or less. 3. The value (M) obtained by dividing the bending stiffness value (M2) of the valley bottom (P2) by the bending stiffness value (M3) of the peak portion (P3).
2 / M3) is 0.85 or more and 0.95 or less.
Or the shaft for golf clubs according to claim 2. 4. A value obtained by dividing a distance from the tip to the peak portion (P3) by a distance from the tip to the grip center position (P1) is not less than 0.35 and not more than 0.55. The golf club shaft according to any one of the above. 5. The distance from the tip to the valley bottom (P2) is:
The value divided by the distance from the tip to the grip center position (P1) is 0.50 or more and 0.70 or less.
The golf club shaft according to any one of the above. 6. A driver using the golf club shaft according to any one of claims 1 to 5.