JPS6217089Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a shaft for a golf club.

Conventionally, to obtain a golf club shaft made of FRP, a twisted continuous carbon fiber filament group (usually twisted 15 times per 1 m) is used as the continuous filament group, and a liquid thermosetting resin is applied to this filament group. The impregnated material is formed into a shaft shape by a filament winding method, the resin of this molded object is then heated and hardened, and the surface of the resin-cured shaft is subsequently ground.

According to the inventor's experience, the fatigue strength of the shaft after grinding is higher than that of the shaft before grinding (which can withstand more than 150,000 vibrations in the fatigue test described below). (It can withstand only about 30,000 vibrations.) In order to eliminate this problem, we conducted various experiments to develop the present invention, and found that the twisted continuous carbon fiber filament described above If a continuous carbon filament group with no twist is used instead of a group of twisted carbon filaments, the fatigue strength of the shaft before grinding will be slightly lower than when a filament group with twist is used, but the fatigue strength of the shaft after grinding will be lowered. I learned that the grinding speed can be significantly improved compared to the grinding shaft using a twisted filament group (improved from about 30,000 cycles mentioned above to 150,000 cycles).

The shaft for a golf club according to the present invention was devised based on such knowledge, and is a shaft for a golf club obtained by a filament winding method from a group of continuous carbon fiber filaments and a liquid thermosetting resin, The structure is characterized in that at least 30% by volume of the fiber filaments are continuous carbon fiber filaments without twist.

In this invention, at least 30% by volume of the CF group, which has no torsion, is used.If less than 30% by volume is used, holes, gaps, etc. will occur on the outer surface when polishing and grinding. This is because it has the disadvantage of not increasing fatigue strength.

An example of a CF group with no torsion is Toray
The company's product name is Trading Card T-300B.

Examples of liquid thermosetting resins include epoxy resins and polyester resins.

According to the present invention, since the CF group with no torsion is used, the static strength and fatigue strength of the golf club shaft obtained are increased, the shaft is less likely to break during use, and can be used for a longer period of time.

In addition, by using a CF group with no twisting at all, it becomes easy to impregnate the liquid thermosetting resin between the unit filaments, and when the surface of the resulting golf club shaft is polished or ground, there will be no gaps or cracks on the surface. A very beautiful outer surface is obtained with no visible cavities.

The golf club shaft of the present invention has a lower CF group content compared to golf club shafts obtained using conventional twisted CF groups (CF
Although there is an inconvenience that the tension applied to the CF group is the same (if the tension applied to the CF group is the same), this is because the tension applied to the CF group during filament winding is lower than the conventional 1.5 to 5.
This can be solved by making the content of the CF group twice as large (300g to 2000g for the tension fed out from the CF group bobbin) to make the content of the CF group the same.

In addition, in manufacturing the golf club shaft of the present invention, a conventional torsion material impregnated with resin is used.
The CF group is first wound around a mandrel, and then, while the resin is uncured, a material consisting of a continuous carbon fiber filament and a liquid thermosetting resin is applied to the outer layer, which contains at least 30% by volume of continuous carbon fiber filaments without any torsion. It can also be applied.

The shaft for a golf club thus obtained has an inner layer of a conventional filament winding layer made of CF group fibers, and an outer layer of a filament winding layer to which the technology of the present invention is applied.

The thickness of the outer layer is usually about 0.8 to 1.0 times the thickness of the inner layer.

When the surface of the shaft for a golf club of the present invention is polished or ground, the surface becomes smooth and beautiful, so when overcoating the pipe with paint, the overcoat can be completed with only one coat of paint.

On the other hand, with conventional golf club shafts, even if the surface is polished or ground, there are gaps and voids on the surface, so it is necessary to fill those gaps and voids with sealing material beforehand. It cannot be coated.

An example of manufacturing the golf club shaft of the present invention will be described below.

Manufacturing example 1 Using a completely untwisted CF group (manufactured by Toray Industries, trade name: Torayca T-300B) (the volume percentage of the untwisted CF group is 100%), the tension for feeding from the bobbin was increased from the conventional 200g to 800g. After impregnating it in liquid epoxy resin, it was wound around a tapered mandrel at a winding angle of 22° using the filament winding method, and then cured in a heated oven.

The obtained golf club shaft was as shown in Fig. 1, with a large diameter portion of 15 mmφ, a narrow diameter portion of 9 mmφ,
It was 1200mm long.

The wall thickness was 1 mm at the end of the large diameter part, 2 mm at the end of the small diameter part, and the thickness was changed gradually and uniformly in the middle. When this shaft was subjected to a cantilever fatigue test, no abnormalities were observed even after 150,000 cycles.

When the outer surface of the resulting golf club shaft was polished using a centerless machine (the polished portion was reduced by 0.5 mm in pipe thickness), the outer surface was extremely smooth and beautiful.

When the obtained golf club shaft was subjected to a cantilever stress test, it was OK even after 150,000 cycles.

On the other hand, golf club shafts obtained using the conventional CF group and liquid epoxy resin in the same manner as described above passed the cantilever stress test even after 150,000 cycles before grinding, but after grinding, , it was out.

In the cantilever stress test, the large diameter portion of the golf club shaft 1 obtained as shown in FIG.
The tips of the narrow diameter portions are each oscillated by 130 mm with respect to the center line of the golf club shaft, and the number of times until the golf club shaft breaks is shown.

As the amplitude means, a gear motor rotating at 60 revolutions per minute was used.

Production example 2 One CF group with no twist (manufactured by Toray Industries, trade name: Trading Card) and one CF group with conventional twist (manufactured by Toray Industries, trade name: Trading Card A) are used together (for all filament groups). The volume% of the untwisted CF group is 50
%), otherwise a golf club shaft was produced by the same method as described in Production Example 1, and a beautiful pipe having an appearance similar to that of the golf club shaft obtained in Production Example 1 was obtained.

When this golf club shaft was subjected to a cantilever stress test in the same manner as in Production Example 1, it was OK even after 70,000 cycles.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an example of the golf club shaft of the present invention. FIG. 2 is an explanatory diagram for explaining a cantilever stress test for a shaft for a golf club. 1...Shaft for golf club.

Claims (1)

[Scope of utility model registration request] A shaft for a golf club obtained by a filament winding method from a continuous carbon fiber filament group and a liquid thermosetting resin, wherein at least 30% by volume of the continuous carbon fiber filament group is a continuous carbon fiber filament group without twist. Shaft for golf clubs.