KR920002103B1 - Golf shaft manufacturing method - Google Patents

Abstract

A fiber reinforced golf shaft is manufctured by forming a partially reinforced layer on the step part of a step-tapered steel mandrel by multi-laminating a carbon fiber reinforced resin, while the fiber orientationg angle is kept in the range of 0- 45 degree, (B) successively laminating on the mandrel a bias layer with the fiber orientation angle of 45 degree and a straight layer with the fiber orientation angle of 0 degree, and (C) winding the heat-shrinkable tape on the laminated mandrel, followed by heat-hardenin. The produced golf shaft shows an improved torsional property and much less weight.

Description

Manufacturing method of fiber reinforced golf shaft

1 is a cross-sectional view of a mandrel that has been used in a conventional method for manufacturing a golf shaft.

2 is a cross-sectional view of a stepped wave mandrel suitable for practicing the method of the present invention.

3 shows a method of forming a partial reinforcement layer of the method of the present invention.

4 is a view showing a method of forming a carbon fiber reinforcement layer when manufacturing a golf shaft.

5 is a cross-sectional view of the present invention golf shaft.

6 is a cross-sectional view of a conventional golf shaft.

* Description of the main parts of the drawings

1: body body 2: bat

3: tip part 3 ': step

4: prepreg sheet 5: partial reinforcing layer

6: prepreg sheet 7: carbon fiber layer

The present invention relates to a method for producing a fiber reinforced golf shaft having excellent torsion characteristics. In particular, the present invention relates to a method for manufacturing a fiber-reinforced golf shaft in which the torsional characteristics and product weight are greatly improved by reinforcing the inside of the tip portion of the shaft using a carbon fiber-reinforced prepreg.

Fiber reinforcement materials are not only superior in strength and inelasticity compared to steel but also excellent in fatigue strength and chemical resistance, so not only sports fields such as fishing rods, tennis rackets and golf shafts, but also automobile drive shafts and aircraft structural materials. It is widely used as a high strength, high elastic, lightweight structural material. When the golf shaft is manufactured with such fiber reinforced materials, the weight of the golf shaft can be significantly reduced compared to conventional steel shafts (fiber reinforced shafts are 70-80 g compared with steel shafts of 120 g). The weight of the golf club is greatly reduced. Golf clubs must have a great distance from the ball and the ball must be accurate. From this point of view, if you hit the ball with a lightweight golf club, the swing speed can be increased, so it is possible to greatly increase the distance. However, this fiber reinforced golf shaft has a disadvantage in that the torsion characteristics are bad.

If the torsional characteristics are bad, the ball head is hit by a sweet spot of the club head when the ball is hit. In view of these disadvantages, the conventional method attempted to improve the torsion characteristics, firstly, the fiber orientation angle of the bias layer (the angle of the carbon fiber fabric in the prepreg sheet with the shaft side) is approximately ± 45 ° and the prepreg How to thicken the sheet several times; Second, a method of laminating a prepreg sheet such that the steel or aluminum alloy is used as the inner tube and the carbon fiber (mesh) fabric structure is the same as the shaft direction (0 °) is used.

However, in the first method, when the orientation angle of the fiber is about ± 45 °, the torsion characteristics are improved, but the flexural rigidity is greatly reduced, and at the same time, the weight of the shaft is increased. In the second method, since the steel inner tube is used, the weight increases, which adversely affects the weight reduction, which is the biggest advantage of the carbon fiber shaft.

The present inventors have carefully studied these disadvantages, and as a result, have succeeded in the manufacturing method of the shaft which improved the torsional characteristics while preserving all the characteristics required for the golf shaft, and completed the present invention.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of manufacturing a golf shaft in which the torsion characteristics are greatly improved while preserving the existing characteristics required for the shaft by partially reinforcing the inside of the tip in manufacturing the shaft made of carbon fiber material.

The present invention relates to a method for manufacturing a carbon fiber-reinforced golf shaft, which first uses a carbon-fiber-reinforced prepreg within 300 mm from the lower end of the mandrel so that the fiber orientation angle (θ) is 0 to ± 45 degrees. To form a partial reinforcement layer, and a prepreg sheet cut to a certain dimension on the bias layer and a straight layer, and then heat-cured to manufacture a shaft. The golf shaft produced by the method of the present invention has almost no increase in flexural strength and weight, and the partial reinforcement layer is placed inside the shaft to have excellent quality with no significant change in torsion and torsional characteristics.

Hereinafter, the present invention will be described in detail with reference to the drawings. After preparing a step taper type steel mangr 1 having the shape shown in FIG. 2 and applying a release agent and an uncured epoxy resin in a solid state at room temperature, a mesh using carbon fibers (mesh) The prepreg sheet 4, which is semi-cured by epoxy resin impregnated into the fabric structure, is cut into pre-designed dimensions, and the water layer (multiple layers) is formed on the step 3 'of the mandrel as shown in FIG. Lamination) to form a partial reinforcement layer.

Next, the bias layer (θ angle ± 45 ° in FIG. 4) and the straight layer (θ angle 0 ° in FIG. 4, parallel to the shaft axis S), respectively, cut into predesigned dimensions as shown in FIG. The water layer is laminated, wrapped on the heat shrink tape, and subjected to an external pressure, and then heat-hardened in a hot air electric furnace, and the shaft is pulled out to obtain a shaft shaped as shown in FIG.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

Prepare the steel stepte wave form shown in Fig. 2 with the diameter of the upper end of 12.8mm, the diameter of the lower end of 4.2mm and the length of 1,300mm and the step of 300mm from the end of the lower end. Cured epoxy resin was applied. Then, the fiber orientation angle (θ) was 0 degrees (shaft) using a prepreg sheet (63% carbon fiber thickness, 0.15mm thickness, trade name: Torayca P3051-15) in which the carbon fiber was impregnated with epoxy resin and semi-cured. Axially) was cut to a constant dimension and then laminated by the method shown in FIG. 3 to form a partial reinforcement layer. Next, using the same prepreg sheet as described above, the bias layer (θ angle ± 45 ° in FIG. 4) was laminated three times with the fiber orientation angle ± 15 degrees by the method shown in FIG. Θ angle ± 45 °) was laminated three times. The polypropylene tape was wound on the carbon fiber layer made as described above, heated in a hot air oven at 13 ° C. to fully cure the epoxy resin, and the mandrel was pulled out to cut the length of the shaft to 1,120 mm to manufacture a golf shaft. The diameter of the golf shaft thus manufactured was 15.5 mm at the upper end and 0.5 mm at the lower end.

Example 2

A shaft was manufactured in the same manner as in Example 1 except that the carbon fiber orientation angle of the partial reinforcement layer was ± 15 degrees. The diameter of the golf shaft thus manufactured was 15.5 mm at the upper end and 8.5 mm at the lower end.

Example 3

A shaft was manufactured in the same manner as in Example 1 except that the carbon fiber orientation angle of the partial reinforcement layer was ± 30 degrees. The diameter of the manufactured golf shaft was 15.5 mm at the upper end and 8.5 mm at the lower end.

Example 4

A shaft was manufactured in the same manner as in Example 1 except that the carbon fiber orientation angle of the partial reinforcement layer was ± 45 degrees. The diameter of the manufactured shaft was 15.5 mm at the upper end and 8.5 mm at the lower end.

Comparative Example 1

After applying the release agent and the uncured epoxy resin to the straight tap wave steel steel rudder with a diameter of 12.8mm at the upper end, 4.2mm at the lower end, and 1,300mm in length, the carbon fiber is impregnated with the epoxy resin and semi-cured. Using a prepreg sheet (63% carbon fiber content, 0.15mm thickness, trade name: Torayca P3051-15), the bias layer is first wound three times with a fiber orientation angle of ± 15 degrees and then stacked on top of the straight layer (fiber angle 0 degrees). After winding three times to make a carbon fiber layer, and then covered with polypropylene tape and heated in a hot air oven at 130 degrees Celsius for 2 hours to cure the epoxy resin, pull out the mandle and cut the shaft to 1,120mm length The shaft was made. The diameter of the golf shaft thus manufactured was 15.5 mm at the upper end and 6.9 mm at the lower end.

Comparative Example 2

A shaft was manufactured in the same manner as in Comparative Example 1 except that the number of bias layers having a fiber orientation angle of ± 15 degrees and the number of straight layers (fiber angle of 0 degrees) were 4, respectively. The diameter of the manufactured shaft was 16.1 mm at the upper end and 7.3 mm at the lower end.

Comparative Example 3

A shaft was manufactured in the same manner as in Comparative Example 1 except that the bias layer fiber orientation angle was ± 35 degrees. The diameter of the manufactured shaft was 15.5 mm at the upper end and 6.9 mm at the lower end.

[Comparative Example 4]

Steel pipes were used as inner tubes and carbon fibers were laminated three times on the fiber orientation angle of 0 degrees. The diameter of the shaft thus prepared was 15.8 mm at the upper end and 8.5 mm at the lower end.

Comparative Example 1 is a sample produced by a conventional method, Comparative Example 2 is a method for improving the conventional torsion characteristics, the thickness of the bias layer is left as it is, the thickness of the fiber orientation angle is left as it is, and Comparative Example 3 is the fiber of the bias layer The angle is enlarged. On the other hand, Examples 1, 2, 3 and 4 are manufactured by the method of the present invention, i. The products were measured for physical properties by the following method, and the results are shown in Table I.

The flexural stiffness was shown as the amount of deflection at the lower end of the shaft, after fixing the 925mm point horizontally at the lower end of the shaft and applying a weight of 2.4kg at the 175mm position from the lower end.

Torsion characteristics were measured by measuring the torsion angle at the lower end of the shaft when the upper end of the shaft was fixed and a constant torsional force (13. 85 kgf · cm) was applied to the lower end.

TABLE 1

It is clear from the above results that, as compared with the carbon fiber reinforced shaft of Comparative Example 1, the torsional characteristics were improved as the bias layer was thickened in Comparative Example 2, while the weight of the shaft was greatly increased. By increasing the orientation angle to ± 45 degrees, the torsion characteristics were improved, but the flexural rigidity was greatly reduced. In addition, in the case of Comparative Example 4, the shaft made of steel as an inner tube to reinforce carbon fiber, which is very high in weight, has no advantage as a carbon fiber material golf shaft.

On the other hand, in the case of the shaft obtained by the method of partially reinforcing within 300 mm of the present invention, as shown in Table I, when the fiber orientation angle of the reinforcing layer is ± 45 degrees (Example 4), the degree of improvement of the torsion characteristics is greatest and the shaft is The weight was also light and there was no drop in flexural rigidity.

As described above, the shaft of the present invention partially reinforces the inside of the shaft within 300 mm from the lower end of the shaft by using a carbon fiber reinforced prepreg, and thus has characteristics such as weight, flexural rigidity, and the like required for the shaft. The effect which drastically improved the torsion characteristic was achieved, maintaining it as it is.

Claims (2)

In the method of manufacturing a fiber reinforced golf shaft, a stepped wave shaped nalral having a step portion formed at a lower end thereof is laminated with a water layer laminated on the step portion so that the fiber orientation angle is in a range of 0 to ± 45 degrees. Forming a reinforcing layer, and subsequently laminated with a bias layer having a mandrel of the fiber orientation angle of ± 45 degrees and a straight layer having a fiber orientation angle of 0 degrees, and then heat-cured by winding a heat shrink tape thereon, characterized in that the manufacturing Method of manufacturing fiber reinforced golf shafts. The method according to claim 1, wherein the partial reinforcement layer of the carbon fiber reinforced resin has a length within 300 mm from the lower end and a fiber orientation angle is in a range of 0 to ± 45 degrees.

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