JPH06142241A - Manufacture of golf club shaft - Google Patents

Abstract

PURPOSE:To manufacture a golf club shaft having less localized wall thickness and high strength by winding a thermoplastic resin sheet around a mandrel of golf shaft form to the specified thickness, setting the mandrel in a die for treatment under the application of pressure and heat, and cooling treatment under pressure, winding prepreg around the mandrel so treated, and then setting the mandrel in a shaft molding die for formation under the application of heat. CONSTITUTION:A thermoplastic resin sheet 5 is wound around a mandrel 1. This sheet 5 is well releasable from the mandrel 1 and has thickness between 0.4mm and 1.0mm. The mandrel 1 so wound with the sheet 5 is set in a thermoplastic resin layer forming die 6 and treated under pressure and heat. Thereafter, the mandrel 1 is pressed and cooled to form a thermoplastic resin layer 2 on the surface thereof. Furthermore, prepreg 3 is wound around the layer 2 so formed, and the mandrel 1 is set in a shaft forming die 4. In this state, the air is supplied to the mandrel 1 via the hollow section thereof, and then this compressed fluid is blown from a compressed fluid discharge hole 11, thereby applying internal pressure and forming the prepreg 3 under the application of heat.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for manufacturing a golf club shaft, and more particularly to a method for easily manufacturing a golf club shaft by an internal pressure molding method.

[0002]

2. Description of the Related Art In the internal pressure molding method, as shown in FIG. 1, a hollow mandrel 1 having a taper is covered with a release layer 2 for easy release, and the release layer 2 is covered with a prepreg 3. Wind it and set it in the shaft molding die 4, and blow air into the hollow portion of the mandrel 1,
In this method, a compressed fluid (air) is ejected from a compressed fluid discharge hole 11 penetrating the hollow portion of the mandrel 1 to apply an internal pressure to the prepreg 3 to perform heat molding. At this time, since an external pressure is applied to the shaft molding die 4, there is an advantage that a shaft having a smooth surface can be molded.

When a golf club shaft is manufactured by such an internal pressure molding method, a conventional release layer 2 covered with a rubber tube having a shape conforming to the taper of the mandrel 1, or a narrow nylon bag without taper. Was covered on the mandrel 1 and wound according to the taper of the mandrel 1 so that a layer was formed on the surface of the mandrel 1.

However, when a rubber tube is used, in manufacturing the rubber tube, the mandrel is immersed in a latex liquid, vulcanized, and covered with a mandrel, but there is a drawback that the mandrel is rusted by the latex liquid. It was Therefore, it is necessary to replace the mandrel for forming the rubber tube with the mandrel for manufacturing the shaft.

In the case of covering with the elongated nylon bag, after inserting the mandrel into the nylon bag,
There is a drawback that it takes time and effort because it is necessary to wrap the surplus of this nylon bag around the surface of the mandrel.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a method for manufacturing a golf club shaft, which has better working efficiency than the conventional internal pressure molding method or internal pressure holding tube. .

[0007]

In order to solve the above problems, the golf club shaft manufacturing method according to the present invention comprises:
Golf shaft shaped mandrel with thickness 0.4-1.0
mm thermoplastic resin sheet is wound, the mandrel wound around the thermoplastic resin sheet is set in a thermoplastic resin layer forming die, and the thermoplastic resin is heated and cooled under pressure. A step of forming a layer on the mandrel, a step of rolling a prepreg on the thermoplastic resin layer, a step of setting the mandrel rolling the prepreg on a shaft molding die, between the mandrel and the thermoplastic resin layer It is characterized by including a step of injecting a compressed fluid and performing heat molding.

According to the present invention, since the release layer is formed by using the thermoplastic resin, it is not necessary to perform vulcanization as in the case of using the rubber tube, and it is not necessary to change the mandrel. Moreover, it is not necessary to wind the extra portion along the mandrel as in the case of using a nylon bag.
Therefore, there is an advantage that workability is significantly improved.

[0009]

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, in the aforementioned hollow,
Compressed fluid ejection hole 11 for ejecting air (compressed fluid)
As shown in FIG. 2, the thermoplastic resin sheet 5 is wound around the mandrel 1 on which is formed.

The thermoplastic resin sheet may be any one as long as it has a good releasability from the mandrel. For example, it can be a urethane resin sheet, an acrylic resin sheet, a vinyl chloride resin sheet, or the like. The thickness of the sheet 5 is 0.5 to 1.0 mm. If the thickness of the sheet is less than 0.4 mm, a thermoplastic resin layer having a sufficient thickness may not be formed, while if it exceeds 1.0 mm, it becomes difficult to control the thickness of the thermoplastic resin layer. .

The mandrel 1 thus wound with the thermoplastic resin sheet 5 is set in the mold 6 for molding the thermoplastic resin layer, heated under pressure, and then cooled under pressure to form the thermoplastic resin layer 2.
Are formed on the surface of the mandrel 1.

The conditions for pressurizing and heating the thermoplastic resin layer as described above are 12 to 12 under a pressure of 0.5 to 30 kg / cm ^2.
It is preferable to carry out at a temperature of 0 to 210 ° C. Pressure is 0.5
If it is less than kg / cm ² , the flow of the resin in the mold is bad, while if it exceeds 30 kg / cm ² , the machine becomes unnecessarily large and the cost increases.

Further, if the heating temperature is lower than 120 ° C., the thermoplastic resin sheet may not be softened and a thermoplastic resin layer may not be formed. On the other hand, if the heating temperature exceeds 210 ° C., thermal decomposition of the thermoplastic resin may occur. Deterioration occurs due to oxidation.

Such pressurizing and heating time is preferably 5
~ 30 seconds. If it is less than 5 seconds, the thermoplastic resin layer may not be formed, while if it exceeds 30 seconds, deterioration due to heat may occur.

In the present invention, after heating under pressure,
Although it is cooled under pressure, the cooling temperature is preferably 70 to 90 ° C. If it exceeds 90 ° C, the cooling effect is small, while if it is less than 70 ° C, it takes too much time to heat the mold for remolding.

The cooling time is preferably 1 to 4 minutes. 1
If it is less than 5 minutes, the thermoplastic resin may not be sufficiently hardened. On the other hand, if it exceeds 4 minutes, the mold will be too cold and the molding cycle will be long and the cost will be high.

The method of cooling the mold 6 is not limited in the present invention, and it can be cooled by air cooling, water cooling or the like. Further, the pressurization can be performed under the same conditions as the heating.

The thermoplastic resin layer formed as described above may have a thickness of 0.4 to 1.5 mm. 0.
If it is less than 4 mm, the dimensional accuracy of the mold is required. On the other hand, if it exceeds 1.5 mm, the molding pressure of the molded product (compressed fluid)
Becomes weak.

A prepreg is wound around the thermoplastic resin layer thus formed, set in a mold for shaft molding, and air is supplied from the hollow portion of the mandrel 1, and the compressed fluid is discharged through a compressed fluid discharge hole. Then, the prepreg is injected to heat the prepreg while applying an internal pressure to the prepreg. The prepreg used at this time may be one in which reinforcing fibers are impregnated with a resin and heated to be in a semi-cured state, or one in which the reinforcing fibers are simply impregnated with a resin and not heated can be used.

[0020]

[Example] Vinyl chloride sheet (0.5 mm) on the mandrel
(Thickness), the mandrel is set in a mold for molding a thermoplastic resin layer, and the mandrel is placed under a pressure of 5 kg / cm ² for ² minutes.
It was heated under pressure at 00 ° C. for 10 seconds. Then, the mold temperature was cooled to 160 ° C. under the same pressure, and held for 2 minutes.

Then, after taking out from this mold, a prepreg is wound in the same manner as in the conventional case, and the shaft forming mold 4 is used.
And blow air from the hollow part of the mandrel,
Air was injected from the compressed air injection hole 11 between the thermoplastic resin layer 2 and the mandrel 1 to perform heat molding. At this time, the thickness of the thermoplastic resin layer was 1 mm.

As a comparison, using a nylon tube, a golf club shaft manufactured in the same manner was manufactured, and the results of measuring uneven thickness, ring fracture and 3-point bending strength are shown in Table 1.

Table 1 Examples Comparative Examples Eccentricity (mm) (max) 0.05 0.13 Ring crush (kg / 5 mm) 29 23 Three-point bending fracture (kg) 75 62

[0024]

As described above, according to the golf club shaft manufacturing method of the present invention, the thermoplastic resin sheet is used and the thermoplastic resin layer (release layer) is formed. Therefore, there is an advantage that the golf club shaft can be manufactured extremely efficiently. Further, there is an advantage that a golf club shaft having less uneven thickness and good strength can be manufactured as compared with the conventional one.

[Brief description of drawings]

FIG. 1 is a sectional view for explaining a method for manufacturing a golf club shaft by an internal pressure molding method.

FIG. 2 is an explanatory diagram for explaining the manufacturing method of the present invention.

FIG. 3 is an explanatory diagram for explaining the manufacturing method of the present invention.

[Explanation of symbols]

 1 Mandrel 11 Air Discharge Hole 2 Release Layer 3 Prepreg 4 Shaft Mold 5 Thermoplastic Resin Sheet 6 Thermoplastic Mold

Claims (2)

[Claims] 1. A step of winding a thermoplastic resin sheet having a thickness of 0.4 to 1.0 mm around a golf shaft-shaped mandrel, wherein the mandrel wound around the thermoplastic resin sheet is used for forming a thermoplastic resin layer. Set in a mold, pressure heating and pressure cooling to form a thermoplastic resin layer on the mandrel, a step of winding a prepreg on the thermoplastic resin layer, a mandrel winding the prepreg A method of manufacturing a golf club shaft, comprising: a step of setting a mold in a mold for shaft molding; and a step of injecting a compressed fluid between the mandrel and a thermoplastic resin layer to perform heat molding. 2. The thickness of the thermoplastic resin layer is 0.4 to
The golf club shaft manufacturing method according to claim 1, wherein the length is 1.5 mm.