JPH0938254A - Frp-made golf club shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an FRP-made golf club shaft by which an actual hitting feeling is improved and which can easily control the hitting-out direction of a ball and by which a carry can be increased. SOLUTION: In an area of 260mm toward the grip side from the upper end of a hosel 12 of a club head 1 in a golf club shaft 2, the rigidity ratio, α=(GJ/EI) by dividing torsional rigidity GJ by flexural rigidity El is set so as to become large by 0.1% or more per 10mm as it proceeds to the tip of the golf club shaft 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an FRP golf club shaft.

[0002]

2. Description of the Related Art In recent years, many woods are made of metal and have a large hollow shape. Compared to woods, woods have a moment of inertia I _G about a vertical line V including the center of gravity 1g of the club head 1 shown in FIG. Is large, which makes it easy to obtain a flight distance.
On the other hand, in the golf club shaft 2 made of FRP, it becomes necessary to reinforce the thin tip portion 20 with the increase in size of the wood. Therefore, the reinforcing fibers having the orientation angle set to 0 ° are mixed in the tip portion 20. ing.

[0003]

However, the orientation angle is 0 °.
Since the reinforcing fibers are arranged along the axis C of the shaft 2, the flexural rigidity EI of the shaft 2 is increased, but the torsional rigidity GJ of the shaft 2 is not increased.
Therefore, when the ball is hit at a position deviated from the center of the head 1, the tip 20 is twisted by the large moment of inertia I _G of the head 1, so that the face surface 11 of the head 1 rotates around the vertical line V. Therefore, it becomes difficult to control the launch direction of the ball. That is, when the ball is hit at a position deviated from the center of the head 1, the ball jumps out in a direction different from the intended direction. Also,
As the face surface 11 rotates, the moment of inertia I _G of the head 1 cannot be sufficiently transmitted to the ball, which causes a reduction in flight distance.

Further, as described above, when the flexural rigidity EI of the tip portion 20 of the shaft 2 is increased, the tip portion 20 of the shaft 2 becomes hard and the so-called head running becomes poor, that is, the tip portion 20 is sufficient. For that reason,
The actual hit feeling (feel when hit) deteriorates. Moreover, if the tip portion 20 is not sufficient, the impulse given to the ball becomes small, and the flight distance cannot be sufficiently extended.

The present invention has been made in view of the above-mentioned conventional problems, and it is an FRP golf club shaft capable of improving the actual hit feeling, facilitating the control of the ball launching direction, and increasing the flight distance. Is to provide.

[0006]

In order to achieve the above object, the FRP golf club shaft of the first invention is twisted in a region of 260 mm from the upper end of the hosel of the club head to the grip side in the golf club shaft. Rigidity ratio α = (GJ
/ EI) is set to increase by 0.1% or more per 10 mm toward the tip of the golf club shaft.

In the FRP golf club shaft of the second aspect of the invention, the rigidity ratio α = the torsional rigidity GJ divided by the bending rigidity EI in the region of 260 mm from the upper end of the hosel of the club head to the grip side in the golf club shaft. A region where (GJ / EI) increases by 0.5% or more per 10 mm toward the tip of the golf club shaft is set over a range of 50 mm or more.

In the FRP golf club shaft of the third invention, the rigidity ratio α = (torsional rigidity GJ / The flexural rigidity EI) is set to be 4% or more larger at the location of 220 mm than at the location of 300 mm.

In the FRP golf club shaft of the fourth invention, the reinforcing fibers set in the orientation angle of 30 ° to 60 ° are
From the upper end of the hosel of the club head on the golf club shaft to the grip side within a range of 200 mm or more,
At least one layer is provided in the range of 400 mm or less. The orientation angle means the angle A formed by the axis C of the shaft 2 and the reinforcing fiber 22 in FIG.

[0010]

Next, the principle of the present invention will be described. Since the tip portion 20 of the shaft 2 in FIG. 1 is thin, it is easily twisted. For example, the tip portion 20 has an orientation angle of 30.
By mixing reinforcing fibers of 60 ° to 60 °, the tip 2
The torsional rigidity GJ of 0 can be increased. If the torsional rigidity GJ is increased, the tip portion 20 is less likely to be twisted, and thus the face surface 11 is less likely to rotate when hit,
Therefore, it becomes easy to control the ball launching direction. Further, since the face surface 11 does not easily rotate, the moment of inertia I _G of the head 1 can be sufficiently transmitted to the ball, so that the flight distance is also improved.

On the other hand, the reinforcing fibers having an orientation angle of 30 ° to 60 ° do not increase the bending rigidity of the shaft 2 to a great extent, and therefore the tip portion 20 of the shaft 2 is unlikely to be hard, and therefore the actual feel is poor. There is also no cause for a decrease in flight distance. That is, the object of the present invention is achieved by increasing the torsional rigidity GJ without increasing the bending rigidity EI of the tip portion 20 of the shaft 2.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, the shaft 2 is
Hosel 1 of head 1 which consists of a hollow tapered circular tube
The rigidity ratio α is set to increase from the upper end of the shaft 2, that is, from the tip 21 of the shaft toward the grip 23 in the region of 0 mm to 300 mm. Here, the rigidity ratio α is expressed by the following equation (1). α = (GJ) / (EI) (1) However, G: Shear elastic modulus (rigid modulus) J: Pole moment of inertia of section E: Elastic modulus of elasticity (Young's modulus) I: Second moment of area

Here, in an isotropic material such as metal, the shear elastic modulus G and the Young's modulus E have the following relationship. E = 2G (1 + μ) (2) where μ: Poisson's ratio Therefore, in the metal golf club shaft, the rigidity ratio α = GJ / EI becomes a constant value.

However, in the FRP golf club shaft, the torsional rigidity GJ and bending rigidity EI change depending on the orientation of the reinforcing fibers. That is, the reinforcing fiber having the orientation angle A (FIG. 2) set to 0 ° hardly contributes to the torsional rigidity GJ but greatly contributes to the bending rigidity EI. On the other hand, the reinforcing fibers having the orientation angle A (FIG. 2) set to 30 ° to 60 ° contribute to the torsional rigidity GJ and do not significantly contribute to the bending rigidity EI.

Therefore, in this embodiment, the reinforcing fiber 22 and the auxiliary reinforcing fibers 22A to 2A are set in the state shown in FIG.
2C was installed. In FIG. 3, the distance from the tip 21 of the shaft is the horizontal axis, and the radial position of the shaft is the vertical axis.
The orientation, position, type, etc. of the reinforcing fibers 22, 22A to 22C are shown. First, a layer of carbon fibers 22 having an orientation angle A = 0 ° is provided on the innermost side, the outermost side and the middle in the radial direction of the shaft over the entire length of the shaft. On the other hand, at the tip portion 20 (FIG. 1) of the shaft, a layer of a pair of first auxiliary reinforcing fibers 22A and 22B made of carbon fibers having an orientation angle A = 45 ° is provided from the middle to the inside in the radial direction. It is provided over a range of 200 mm or more and 400 mm or less from 21 toward the grip side. In addition, at the tip portion 20 (FIG. 1) of the shaft, the orientation angle A =
A layer of the second auxiliary reinforcing fiber 22C made of 0 ° glass fiber is provided from the tip end 21 toward the grip side over a range of 400 mm or more.

The first auxiliary reinforcing fibers 22A, 22B and the second auxiliary reinforcing fibers 22C are formed so as to be shorter on the inner peripheral side and longer on the grip side as they are arranged on the outer peripheral side. There is. The second auxiliary reinforcing fibers 22C made of glass fibers have a smaller Young's modulus than the first auxiliary reinforcing fibers 22A, 22B made of carbon fibers. In addition to these fibers, polyamide fibers and metal fibers can also be used as the reinforcing fibers.

Here, the second moment of area I and the second polar moment of area J are both proportional to the fourth power of the diameter D when the structure is a circular pipe. On the other hand, since the shaft 2 becomes thinner toward the tip, the geometrical moment of inertia I and the geometrical moment of inertia J are generally smaller. But,
Some reinforcing fibers 22 having an orientation angle A = 0 ° that contribute to the second moment of area I are provided relatively close to the outer circumference of the shaft 2. Therefore, the value of the second moment of area I is It becomes much smaller than the moment J toward the tip 21. Therefore, at the tip portion 20, the rigidity ratio α
= (GJ / EI) gradually increases.

[0018]

EXAMPLES Hereinafter, the reinforcing fibers 22, 22A as described above will be described.
22C is provided on the shaft 2, and the rigidity ratio α =
The results of measuring (GJ to EI) are shown in FIGS. In these three examples, the shaft tip 21
In the region from 220 mm to 300 mm, the rigidity ratio α =
The value gradually increased as (GJ / EI) reached the tip 21 of the shaft. The rigidity ratio α could not be measured in the portion from the tip 21 to 200 mm due to the measuring instrument, but it is estimated that the rigidity ratio α increases toward the tip. Further, in a region from the tip of the shaft 2 to 300 mm, a region in which the rigidity ratio α = (GJ / EI) increases by 0.5% or more per 10 mm is formed over a range of 80 mm or more as it goes to the tip 21 of the shaft. It was Furthermore, the rigidity ratio α measured at a point about 220 mm from the tip of the shaft is 30
8% more than the rigidity ratio α measured at a point of about 0 mm
It was bigger than that.

5 (a) and 5 (b) are measurements of the rigidity ratio α of the conventional shaft, and the rigidity ratio α of the shaft in FIG. 5 (a) becomes smaller toward the tip. Also, FIG.
The rigidity ratio α of the shaft in (b) was constant regardless of the axial position of the shaft.

When a ball is hit with a shaft having a rigidity ratio α shown in FIGS. 4 (a) to 4 (c), FIG.
The flight distance was longer than that of the shaft (b), and the ball control was more accurate. Moreover, the actual hit feeling was also excellent.

By the way, the first auxiliary reinforcing fiber 22 of FIG.
Even if A and 22B are provided over the entire length of the shaft 2, the shaft 2 having a large torsional rigidity GJ can be obtained. But,
This increases the content of the reinforcing fibers, which causes a cost increase, and the weight of the shaft is 20% to 30%.
There is a problem that it becomes heavy, the swing becomes dull, and it becomes inconvenient to carry. In contrast, this FR
In the P golf club shaft, the tip 2 of the shaft 2
Since the first auxiliary reinforcing fibers 22A and 22B are mixed in 0, such a problem does not occur.

Further, in the FRP golf club shaft of the present invention, since the orientation angle A of the first auxiliary reinforcing fibers 22A and 22B of the tip portion 20 which has been conventionally the orientation angle A = 0 ° is 45 °, the bending rigidity is increased. EI is lower than before. for that reason,
The shaft is easily broken. Therefore, in this embodiment,
A glass fiber having a small Young's modulus was used as the second auxiliary reinforcing fiber 22C having the orientation angle A = 0 °. Since this glass fiber has a small Young's modulus, it has a large elongation when the shaft 2 is broken, so that the energy required for breaking the tip portion 20 of the shaft 2 becomes large. Moreover, since it is provided near the outer circumference of the shaft 2, it greatly contributes to bending. Therefore, the shaft 2 can be prevented from being completely broken. The second auxiliary reinforcing fiber 22C was not provided in the outermost layer in order to prevent peeling.

[0023]

As described above, according to the present invention,
At the tip of the shaft, the rigidity ratio α obtained by dividing the torsional rigidity GJ by the bending rigidity EI is set to be larger toward the tip of the shaft. Therefore, even if the head has a large moment of inertia, the shaft is unlikely to twist when hit. In addition, since the tip of the shaft is bent, the actual feel at impact is improved, the control of the ball launching direction is easy, and the flight distance is increased.

Further, according to the fifth and sixth aspects of the invention, since the reinforcing fibers having an orientation angle of 0 ° and a relatively small Young's modulus are mixed in at least the tip portion of the shaft, the shaft is broken. Since the energy required for this is large, it is possible to prevent the shaft from being completely broken.

[Brief description of drawings]

FIG. 1 is a front view showing an example of a golf club.

FIG. 2 is an enlarged plan view showing the definition of orientation angle.

FIG. 3 is a graph showing the orientation of reinforcing fibers.

FIG. 4 is a characteristic diagram showing changes in the rigidity ratio α of the first to third examples.

FIG. 5 is a characteristic diagram showing a change in rigidity ratio α of a comparative example.

[Explanation of symbols]

 1: Club head 12: Hosel 2: Golf club shaft 20: Tip part 21: Tip (upper end of hosel) 22A, 22B: First auxiliary reinforcing fiber 22C: Second auxiliary reinforcing fiber

Front page continuation (72) Inventor Ryuichi Hashimoto 7-1, 1-1 Minatojima Nakamachi, Chuo-ku, Kobe City Asics Inc.

Claims (6)

[Claims] 1. A 260 mm portion of the golf club shaft from the upper end of the hosel of the club head toward the grip side.
In the region of, the rigidity ratio α = (GJ / EI) obtained by dividing the torsional rigidity GJ by the bending rigidity EI is set to increase by 0.1% or more per 10 mm toward the tip of the golf club shaft. Golf club shaft. 2. The golf club shaft is 260 mm from the upper end of the hosel of the club head toward the grip side.
In the range up to 50 mm, the rigidity ratio α = (GJ / EI) obtained by dividing the torsional rigidity GJ by the bending rigidity EI increases by 0.5% or more per 10 mm toward the tip of the golf club shaft over a range of 50 mm or more. FRP golf club shaft that has been set. 3. 220 mm from the upper end of the hosel of the club head on the golf club shaft toward the grip side
The FRP golf club shaft has a rigidity ratio α = (torsional rigidity GJ / bending rigidity EI) measured at a point of 220 mm and a point of 300 mm that is 4% or more larger at a point of 220 mm than at a point of 300 mm. . 4. The reinforcing fibers set to have an orientation angle of 30 ° to 60 ° are in a range of 200 mm or more and 400 mm or less from the upper end of the hosel of the club head in the golf club shaft toward the grip side. An FRP golf club shaft having at least one layer. 5. The golf club shaft according to claim 1, 2, 3 or 4, wherein two or more kinds of reinforcing fibers made of different materials having different orientation angles of 0 ° and different Young's moduli are provided. A FRP golf club shaft. 6. The golf club shaft tip according to claim 1, 2, 3 or 4, wherein the first auxiliary reinforcing fiber and the second auxiliary reinforcing fiber having a Young's modulus smaller than that of the first auxiliary reinforcing fiber are provided. A second auxiliary reinforcing fiber, the orientation angle of the first auxiliary reinforcing fiber is set to 30 ° to 60 °, the orientation angle of the second auxiliary reinforcing fiber is set to 0 °, and the second auxiliary reinforcing fiber is provided. Is provided near the outer periphery of the first auxiliary reinforcing fiber and is formed to be long from the tip of the golf club shaft toward the grip side.