JPH0677615B2 - Fiber-reinforced plastic golf club shaft and method for manufacturing the shaft - Google Patents

Description

TECHNICAL FIELD The present invention relates to a shaft for a golf club and a method for manufacturing the shaft.

[Prior Art] A shaft for a golf club is formed in a tapered shape from the end on the grip side to the tip on the head side, but in the conventional shaft, the tapered shape is all straight.

In addition to the steel shaft, there is also a so-called carbon plastic shaft made of a pipe wrapped with fiber reinforced plastic prepreg sheet, but this shaft also has a tapered taper shape, it is lightweight and head speed is increased. , Is gaining popularity because it can be expected to increase the flight distance.

However, this shaft does not always have sufficient strength at the tip end that receives the most impact, and it has the drawback that a high kick point comparable to a steel shaft cannot be obtained.

Various methods have been attempted in order to eliminate this drawback, for example, a method of thickening only the tip portion or winding a reinforcing material, but the shaft manufactured by these methods has a thick portion, Internal stress concentrates on the boundary between the reinforcing material and the shaft during impact, and there is a drawback that the part is easily broken.

The use of high-strength fiber can solve the above-mentioned drawbacks, but the entire shaft becomes hard and cannot be made a shaft having appropriate flexibility and bending.

[Object of the Present Invention] The object of the present invention is to obtain sufficient strength at the tip end without thickening or using a reinforcing material, and further, internal stress is not concentrated upon impact. Therefore, it is an object of the present invention to provide a shaft that hardly breaks and a manufacturing method thereof.

[Means of the Present Invention] The golf club shaft of the present invention by the seat rolling method is composed of a tube in which a prepreg sheet is wound, and the tube has a taper taper shape from the grip end side to the head side. The taper line is not a straight line but is formed as a gentle hyperbolic continuous curve, and the manufacturing method is a taper taper, but the taper line is formed as a gentle hyperbolic continuous curve instead of a straight line. After winding the thermosetting prepreg sheet around gold, the prepreg sheet is heat-cured by a conventional method, and then the cored bar is removed.

[Examples] In the examples shown in the accompanying drawings, FIG. 1 is a core bar for molding used in the method of the present invention, a in FIG. 2 is for longitudinal winding,
b and c show each prepreg sheet for spiral winding.

Although the core metal 1 is tapered toward the tip (the left end in the figure), it is not a mere straight taper shape, but the opposite side ridgelines 1a and 1b have a gentle hyperbolic curve,
The extension lines of the opposite side ridgelines 1a and 1b are 3 to 3 of the core metal 1 on the core metal axis.
It is designed to intersect at a point that is five times longer.

Each of the prepreg sheets 2, 3 and 4 shown in FIG. 2 is composed of a sheet in which a large number of fiber strips 5, 6 and 7 are joined by a binder made of a thermosetting synthetic resin material. However, each sheet is 2c, 2c, 3c, 3c
It is said that 4c, 4c have a slender hyperbolic shape with a gentle hyperbolic shape, and the lengths are equal, and the tips 2a, 3a, 4a have a good grip end.
2b, 3b and 4b are formed in an arc curve (preferably concentric arcs as shown in FIG. 4).

Further, the spacing between the fiber strips 5, 6, and 7 in each sheet is aligned in the longitudinal direction such that the spacing pitch P2 on the grip end side is larger than the spacing pitch P1 on the tip end side.

The above-mentioned shape of each prepreg sheet is designed by the method shown in FIG.

That is, when the diameter of the tip of the core metal is l ', the prepreg sheet tip edge length is πl' and the prepreg sheet grip tip edge length is πl. If the length from the tip of the core to the grip end is L, the length H of the fiber strips arranged on the same plane as the axis of the core is Becomes

The radius R'of the curve at the tip of the prepreg sheet is Becomes

The radius R of the curve at the grip end of the prepreg sheet is R = H + R ′, where θ is the winding angle of the tip end of the spirally wound fiber strip, the fiber strip length H ′ is Becomes

The final winding angle (grip end) θ'is Becomes

If the diameter of the tip of the core bar is 4 mm and the diameter of the grip end of the core bar is 12 mm, the edge length of the prepreg sheet tip is 12.56 m and the grip edge length is 37.68 mm. If the length from the tip of the core metal to the grip end is 11176 mm (44 inches), the fiber length arranged on the same plane as the axis of the core metal is 11176.00.
It will be 07 mm. The radius of the curve at the tip of the prepreg sheet is 558.
It will be 8.00035 mm. The radius of the curve at the end of the prepreg seat grip is 1676.400105 mm.

When the winding start angle of the fiber end of the prepreg sheet that is spirally wound is 45 °, the fiber length (side length) is 12
340.36761mm, and the final winding angle is 13.6333023.
It becomes ゜.

In this embodiment, the prepreg sheet 2 for longitudinal winding is longitudinally wound on the core metal 1 having the above-mentioned tapered curve as shown in FIGS. 3A and 3B, and then the prepreg sheet 3 for spiral winding is placed thereon. Wrap it in a spiral shape with a winding angle θ like ~ d,
Further, the spirally wound prepreg sheet 4 of 4 is spirally wound in the opposite direction at the same winding angle θ, and then the vertically wound prepreg sheet 2 is further wound.

After wrapping the prepreg sheet in multiple layers like this,
The prepreg sheet is heat-cured by heating, and then the cored bar is pulled out to obtain the shaft S made of the wound tube of the prepreg sheet shown in FIG. 3 (i).

Although the shaft manufactured in this manner is formed in a tapered taper shape, the taper line is not a straight line but is formed in a gentle hyperbolic shape, and the following action and effect can be obtained.

(A) The entire shaft, particularly the central portion of a wide range in the longitudinal direction, is slender to make it easy to swing.

(B) The thickness of the tip of the shaft is almost the same as the conventional one, and the strength is sufficient to withstand impact.

(C) Therefore, it is not necessary to apply a reinforcing material to the tip portion of the shaft, and it is not necessary to make the shaft thick.

(D) Since the shaft has a taper with a gentle continuous curve and (c) above, there is no place where stress concentrates at the time of hitting, it is difficult to break and a kick point equivalent to a steel shaft can be obtained. Has become.

In the shaft of the above-mentioned embodiment, even one fiber strip of the prepreg sheet tube has no breaks in the middle and is continuously connected from the tip portion to the grip end portion. It can exert its strength efficiently and is lightweight but has high shot performance.

Moreover, the winding angles of all fiber strips are the same no matter which layer is taken, and the physical properties such as bending and twisting are the same at any point on the circumference of the shaft, eliminating the effects of the physical properties on shots. It has been made reliable.

[Brief description of drawings]

FIG. 1 is a front view of a core bar, FIGS. 2 (a) to (c) are plan views of a prepreg sheet, FIGS. 3 (a) to (i) are views showing a manufacturing process, and FIG. 4 is a prepreg sheet. It is a figure which shows the design method in manufacture. In the figure 1 …… Core bar 2,3,4 …… Prepreg sheet 5,6,7 …… Fiber strip

Claims (2)

[Claims] 1. A prepreg sheet is composed of a bent tube, and the tube has a taper taper from the grip end side to the head side, and the taper line is not a straight line but a gentle hyperbolic continuous curve. Fiber reinforced plastic golf club shaft formed. 2. A thermosetting prepreg sheet is wound around a cored bar which is tapered but has a continuous hyperbolic curve instead of a straight line, and then the prepreg sheet is thermoset by a conventional method. Then, a method for producing a shaft for a fiber-reinforced plastic golf club, which comprises removing the core metal.