JPH11206932A - Golf club - Google Patents

Abstract

(57) [Summary] [Problem] Without impairing the softness of the entire shaft,
Increase the hardness of the shaft tip. The golf club has a flex value of 2.5 kg or less, and is 20% of the entire length of the shaft from the tip of the shaft.
A shaft in a range of less than 25 to 30% of the total length of the shaft from the shaft tip as a front portion, and a shaft extending from a shaft end side end to a shaft end of the front portion. The shaft is a rear portion, and the bending stiffness of the front portion is increased by 5 to 15% from the bending stiffness of the front portion so that the bending stiffness of the front portion is set to a minimum in the longitudinal direction of the shaft. In this example, the shaft rigidity is gradually increased toward the shaft end, but the bending rigidity of the shaft at a position of 750 mm from the shaft end is set to be 2.5 times or less the bending rigidity of the shaft at a position of 150 mm from the shaft end.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a golf club having improved shaft characteristics of a wood golf club provided for a weak player, especially a woman.

[0002]

2. Description of the Related Art Soft golf clubs for women's golf clubs are made of a soft shaft, and the flex value of the cantilever type is 2.5 kg or less. The flex value is a value of a load required to fix the large diameter side (grip side) of the shaft and to bend the small diameter side (head side) of the shaft to a certain value. This is a numerical value obtained by a tip load type measurement method.

[0003]

However, when measuring the bending stiffness at various portions in the longitudinal direction of the shaft with respect to various types of the conventional women's golf clubs, a, b, and b in FIG.
As shown by the curves with c and d, the bending stiffness of the shaft simply increases from the tip (Tip) to the end (Butt) of the shaft (a, b, c in the figure).
Alternatively, it was confirmed that the majority of the type (d in the figure) is such that the rigidity is simply increased toward the distal end while the distal end portion is suppressed to a constant low rigidity. For this reason, the flex value of the entire shaft is originally set to be low for a weak woman, and the bending rigidity at the tip of the shaft is extremely low. As a result, when the ball is hit with the head of the club, the shake at the tip of the low rigid shaft is large, and when the ball is not caught by the core of the head, the torsional deformation of the shaft becomes large. There is a problem that the directionality of the hit ball is not stable. Also,
It has been empirically pointed out that the hit ball has no momentum and the run cannot be extended, and furthermore, there was dissatisfaction that the hit feeling was weak.

Accordingly, an object of the present invention is to provide a golf club in which the hardness of the tip portion of the shaft is increased without impairing the softness of the entire shaft, which is indispensable for a powerless woman.

[0005]

SUMMARY OF THE INVENTION To achieve the above object, the present invention relates to a golf club having a flex value of 2.5 kg or less, wherein the golf club has a flex length of 20 kg or less.
% Of the shaft as a tip portion, a shaft within a range of 25 to 30% to 20 to 35% of the entire length of the shaft from the tip of the shaft as a front portion, and a range from the shaft end side end of the front portion to the shaft end. A rear portion, wherein the bending stiffness of the front portion is increased by 5 to 15% from the bending stiffness of the front portion so that the bending stiffness of the front portion is set to a minimum in the longitudinal direction of the shaft. Inside, the shaft rigidity is gradually increased toward the shaft end, but the bending rigidity of the shaft at a position of 750 mm from the shaft end is set to be 2.5 times or less the bending rigidity of the shaft at a position of 150 mm from the shaft end. is there.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a bending rigidity (EI value, that is, a product of a Young's modulus of a shaft and a second moment of area) at each position in a longitudinal direction of a shaft of a golf club for women according to an embodiment of the present invention. The curve A in the figure
Is the shaft of the golf club of the example, and curve B is the shaft of the golf club of the comparative example. Both the examples and the comparative examples are used for fairway wood clubs belonging to the same category among clubs for various players classified according to head speed, skill, and the like. In addition, the shaft has a carbon fiber reinforced shaft whose outer diameter is tapered toward the distal end. In the shaft of the embodiment, the bending rigidity (average value: 1.85 kg · mm ² × 10 ⁶ ) of the tip portion within a range of 200 mm (19%) from the tip of the shaft is 220 to 380 mm (20 to 35 mm) from the tip of the adjacent shaft. %) (The average value is 1.72 kg · mm ² × 10)
⁶ ) is increased by 7.6%, and the bending rigidity of the shaft in the front part is the minimum value (1.71 kg · mm ² × 1).
It is set to 0 ^6). On the other hand, in the comparative example, the bending stiffness was increased almost monotonously from the position of 150 mm to the position of 900 mm from the tip of the shaft, and the bending stiffness in the range corresponding to the tip portion was 1.46 kg · mm ² × 10 ^{6 on} average. It is set to the degree, and the tip portion has the minimum value of the bending rigidity. For this reason, in the shaft of the embodiment, the rigidity, that is, the hardness of the tip portion of the shaft is increased, so that a sense of firmness at the time of impact, the accuracy of the hitting direction, and the elongation of the run can be obtained. The feeling of unreliable impact peculiar to women's clubs has left the player unhappy with the direction and distance of the hit ball.

In the embodiment, a position 380 mm from the front end which is the Butt side end of the front portion is 9 mm from the front end close to the Butt portion.
The bending stiffness at the rear part up to the 00 mm position is simply increased, and the bending stiffness of the shaft at a position of 750 mm from the tip (3.25 kg · mm ² × 10 ⁶ ) is 150 mm from the tip.
Flexural rigidity of shaft at position (average value 1.87 kg · mm ²
× 10 ⁶ ), which is as low as 1.73 times. On the other hand, in the comparative example, the bending rigidity (4.27 kg · mm ² × 10 ⁶ ) of the shaft at a position of 750 mm from the tip is 150 mm from the tip.
Flexural rigidity of the shaft at the position (1.37 kg · mm ² × 10
⁶ ) 3.11 times higher than that of ⁶ ). For this reason, in the golf club using the shaft of the embodiment, the high rigidity of the tip portion is alleviated by the low rigidity of the rear portion, so that a smooth swing without a sense of incongruity due to the rigidity of the tip portion can be performed. On the other hand, in the comparative example, the hand is rigid and has a characteristic that it is difficult to swing with anxiety about the bending of the tip.

In the case of actually manufacturing the shaft of the embodiment, a commercially available prepreg of a high elastic carbon fiber having a large elastic modulus and good flexibility at a tip portion is added to a prepreg of a normal carbon fiber as a reinforcing material. Affixed. The rigidity of the tip portion can be increased by increasing the thickness of the tip portion instead of changing the type of carbon fiber as described above. However, increasing the outer diameter of the shaft is not preferable because the swing may not be smooth because the player has an image with a particularly hard tip.

Further, the adjustment of the bending rigidity at a position of 750 mm from the tip is performed by setting the arrangement angle of the carbon fibers of the prepreg to be attached to this portion at a high angle with respect to the axial direction of the shaft. It is also possible by reducing the number of shots (pieces / cm) or by changing the type of carbon fiber (decreasing the elastic modulus).

The bending stiffness at each position in the longitudinal direction of the shaft is, as shown in FIG.
Each point is measured by a three-point bending method in which both ends are supported and a load is applied to the midpoint.

[0011]

As described above, according to the present invention, a portion within a range (approximately 218 mm in the case of a normal shaft) corresponding to approximately 20% of the entire length of the shaft from the tip of the shaft is defined as a tip portion of the shaft. Bending stiffness (E
I) is increased, and furthermore, from 25 to 30% to 20 to 20% of the total shaft length from the tip of the shaft adjacent to this tip portion.
The shaft stiffness of the forward portion, which is in the range of 35%, is set to a minimum within the shaft, so that the stiffness of the tip portion is relatively and substantially increased so that when the ball is hit with the club head, Sharpness of the tip part due to the impact of (1) is significantly reduced, and even if the head face is removed from the sweet area, the torsion of the shaft tip part is small, the attitude of the face is small, and the variation in the hitting direction is reduced. Can be smaller. The amount of increase in the bending stiffness of the tip portion is 5 to 15 compared to the front portion.
%, But preferably about 8 to 12%. In addition, by making the tip part hard, it is possible to obtain a solid impact feeling that pushes the ball in the flight direction against the impact at the time of hitting and generate a strong hit ball that can be expected to extend the run it can. Further, in the rear part of the shaft, which is defined as a range from the Butt side end of the front part of the shaft to the end of the shaft,
By gradually increasing the bending stiffness of the shaft from the end of the front portion to the Butt portion, while suppressing the bending stiffness at a position of 750 mm from the shaft tip to less than 2.5 times the bending stiffness at a position of 150 mm from the shaft tip. Further, it is possible to soften the hardness of the entire shaft, thereby alleviating a sense of incongruity at the time of swing caused by the increase in rigidity of the distal end portion. Therefore, even a weak player can make a smooth and powerful swing.

[Brief description of the drawings]

FIG. 1 is a graph showing bending stiffness at each position in a longitudinal direction of a shaft in an example of the present invention and a comparative example.

FIG. 2 is a diagram showing a method for measuring the bending rigidity of a shaft.

FIG. 3 is a graph showing bending stiffness at each position in a longitudinal direction of a shaft of a conventional female golf club.

Claims (1)

[Claims] 1. A golf club having a flex value of 2.5 kg or less, wherein 20% of the total length of the shaft from the tip of the shaft is
A shaft in a range of less than 25 to 30% of the total length of the shaft from the shaft tip as a front portion, and a shaft extending from a shaft end side end to a shaft end of the front portion. A shaft as a rear portion, wherein the bending stiffness of the front portion is increased by 5 to 15% from the bending stiffness of the front portion so that the bending stiffness of the front portion is set to a minimum in the longitudinal direction of the shaft; Although the shaft rigidity is gradually increased toward the shaft end, the bending rigidity of the shaft at a position of 750 mm from the shaft tip is set to be 2.5 times or less the bending rigidity of the shaft at a position of 150 mm from the shaft tip. And golf clubs.