JP2836213B2 - Manufacturing method of golf club shaft - Google Patents

Description

The present invention relates to a fiber reinforced thermoplastic (FRTP)
The present invention relates to a method of manufacturing a golf club shaft manufactured by using a method, wherein reinforcing fibers in a thermoplastic resin serving as a matrix are formed by holding them in a tension-free state without loosening to enhance the reinforcing effect of the reinforcing fibers.

[Conventional technology]

As a method for manufacturing a golf club shaft made of FRTP, there are those disclosed in JP-A-1-185274 and JP-A-2-31770.

According to the production methods described in these publications, a prepreg sheet in which a thermoplastic resin such as polyetheretherketone is impregnated in carbon fiber is wound in a taper shape around a core metal in a heat-softened state in one layer or in multiple layers. Next, a heat-resistant non-adhesive tape such as Teflon tape is wound around the prepreg sheet while applying tension and tightened.Then, the prepreg sheet is housed in a mold and heated and pressed to integrate the prepreg sheet. After cooling, the mold, core metal and the like are removed to form a shaft.

However, in this manufacturing method, since the prepreg sheet is wound around the core metal in a softened state, even if tension is applied to the prepreg sheet, the tension is not transmitted to the internal reinforcing fibers, and the reinforcing fibers in the prepreg sheet after winding are However, it is not necessarily in a tensioned state, so-called tension state, but in a loose state, so-called relaxation state. Then, also in the subsequent heat forming step, only the pressure from the outside to the inside of the shaft acts, so that the reinforcing fibers are formed in a relaxed state.

For this reason, the reinforcing fibers are present in a loosely relaxed state in the thermoplastic resin serving as the matrix, and the reinforcing effect of the reinforcing fibers is not sufficiently exhibited, and the bending rigidity of the shaft is not sufficient. There are inconveniences.

[Problems to be solved by the invention]

Accordingly, an object of the present invention is to provide a method of producing a golf club shaft made of FRTP, in which the reinforcing fibers in the shaft are in a tension state, and the reinforcing effect of the reinforcing fibers is sufficiently exhibited.

[Means for solving the problem]

The problem is that a prepreg made of a reinforcing fiber and a thermoplastic resin is wound around a core mold, and is heated and molded to obtain a cylindrical preform. Then, the preform is formed on the inner surface of the mold by one or more longitudinal steps. The problem is solved by inserting the preformed body into the hollow cylindrical mold having the formed therein and applying heat from the inside to the outside of the preformed body while performing the heat forming.

 Hereinafter, the present invention will be described in detail.

Examples of the thermoplastic resin used in the present invention include engineering plastics such as nylon 6, nylon 66, nylon 11, polybutylene terephthalate, polyoxymethylene (acetal resin), polycarbonate, modified polyphenylene oxide, and polyphenylene sulfide. Especially its heat distortion temperature (ASTMD648,18.6k
g / cm ² ) of 140 ° C. or less are preferred. These may be used alone or as a blended polymer of two or more.

Further, as the reinforcing fibers used in the present invention, carbon fibers, aramid fibers, glass fibers and the like are used,
These may be used alone or in combination of two or more. Further, as a form of the reinforcing fiber, a roving in which a large number of filaments are arranged in one direction is mainly used, but a roving cloth or the like can also be used.

The production of the prepreg composed of the reinforcing fiber and the thermoplastic resin includes, for example, a method in which a powdery thermoplastic resin is sprayed on the reinforcing fiber, and the molten resin is impregnated by heating and melting. It is performed by a method of roving together with the fiber. The amount of reinforcing fibers in the prepreg is preferably about 40 to 80% by volume. The form of the prepreg includes a sheet shape and a tape shape, and a tape shape is preferable from the viewpoint of operability of winding around a cored bar.

Next, such a prepreg is wound around the cored bar 1 in a heat-softened state as shown in FIG. The cored bar 1 is a tapered rod made of metal or the like. The winding direction of the prepreg 2 is such that the angle between the arrangement direction of the reinforcing fibers in the prepreg 2 and the axial direction of the metal core 1 is 0 to 90 degrees, that is,
The fiber direction is appropriately determined in a range from a direction parallel to the axial direction of the cored bar 1 to a direction perpendicular thereto. The number of layers of the prepreg is usually a plurality of layers so as to have a desired thickness, and the fiber direction can be changed in the above-described range for each winding layer.
As a preferred prepreg winding method, there is a method in which a tape-shaped prepreg is spirally wound at an angle for each winding layer.

Next, as shown in FIG. 1, a heat-resistant non-adhesive tape 3 such as a Teflon tape is wound and tightened from above the prepreg 2 on the cored bar 1 while applying tension, and then housed in a heating furnace or the like to be thermoplastic. The prepreg 2 is melted by heating to a temperature higher than the melting temperature of the resin, and the respective layers of the prepreg 2 are melt-bonded and integrated. After cooling, the heat-resistant and non-adhesive tape 3 is removed, and the core bar 1 is removed to obtain a hollow tapered preform 4 as shown in FIG. The reinforcing fibers in the preform 4 in this state are still in a relaxed and relaxed state.

Next, the preform 4 is mounted in a molding die 5 as shown in FIG.

The molding die 5 has a hollow cylindrical shape, an inner surface 6 of which is tapered, and a plurality of steps 7 are formed in the longitudinal direction so that the inner diameter gradually decreases. . The steps 7... May be formed at equal intervals in the longitudinal direction, or may be formed at unequal intervals, and the middle may be longer, and the ends may be shorter.
The reverse may also be the case. The change in inner diameter due to the single step 7 is preferably about 0.2 to 0.4 mm / step. Also,
The inner diameter is slightly smaller than the outer diameter of the preform 4 by 2 to 10%.
It is getting bigger.

The molding die 5 is formed with a plurality of exhaust ports 8 which are opened on the inner surface 6 thereof, and these exhaust ports 8 are connected to an exhaust device (not shown) via an exhaust pipe 9.

Further, the entirety of such a molding die 5 is housed in an autoclave 10 as a heating and pressing device.

As shown in FIG. 3, the preform 4 is mounted inside the molding die 5, and a flexible cover tube 11 made of Teflon or the like is passed through the inside of the preform 4, and both ends of the cover tube 11 Are sealed at both ends of the mold 5, and the inner surface of the preform 4 is covered with the cover tube 11 and the mold 5 is
The gap between the preform 4 and the preform 4 is sealed.

In this state, the exhaust device is operated to exhaust the air in the gap between the molding die 5 and the preform 4, and the inside of the autoclave 10 is heated and pressurized. The pressurized medium at this time may be a gas such as air, or may be a liquid such as polyethylene glycol, water, or oil.

By this heating, the preformed body 4 is again in a molten state, and is pressurized from the inside to the outside by evacuation and pressurization. It is shaped into the shape of the inner surface 6. At this time, the reinforcing fibers in the preform 4 also receive a force in the radially outward direction, and also try to expand, and become a tensioned state from a relaxed state to a loose state. It is also tensioned in two directions, receiving tension in one direction.

If the inside of the autoclave 10 is cooled while maintaining this pressurized state, the reinforcing fibers will be fixed in the thermoplastic resin of the matrix in a tensioned state.

The conditions of this heating and pressurization are as follows: temperature 200-320 ° C, pressure 0.5-5
MPa and the time are about 10 to 60 minutes, but are not limited to these ranges, and can be appropriately changed according to the type of thermoplastic resin used, the dimensions of the shaft, the amount of reinforcing fibers, and the like. The degree of pressure reduction from the exhaust ports 8 is 1 to 10
About kPa is enough.

Then, the mold 5 is taken out from the autograve 10 and
When the mold 5 is removed, the shaft 12 as shown in FIG.
Is obtained. This shaft is subjected to predetermined post-processing as necessary, and becomes a golf club shaft.

In such a manufacturing method, the reinforcing fibers in the shaft are fixed in the thermoplastic resin in a state where the tension is maintained by the application of two radially outward forces and the axial direction. The reinforcing effect of the fiber is sufficiently exhibited, and the amount of deformation when an external force such as a bending external force is applied is reduced, resulting in high rigidity. Also, a step is formed on the obtained shaft in the same manner as a conventional steel shaft, so that the vibration attenuation is not too large and the shot feeling is more metallic than the epoxy matrix.

In the manufacturing method of the present invention, the pressurizing means is not limited to the one using a pressure medium.
Alternatively, a tapered mandrel similar to the above may be pushed in from the large diameter side of the preform 4 to apply a radial outward force and an axial force. In this case, the cover tube 11 is naturally unnecessary.

 Hereinafter, specific examples will be described.

(Example) As a core metal, the outer diameter of the large diameter portion is 14 mm, and the outer diameter of the small diameter portion is 4 m
Prepare a steel product with a length of 1460 mm and a mold release agent applied to the surface of the product.

On the other hand, a prepreg tape having a carbon content of 60% by volume and a basis weight of 220 g / m ² , in which carbon fiber roving was impregnated with polycarbonate, was prepared and wound around a core metal in 12 layers. First 6
For the layer, the angle between the fiber direction of the tape and the axial direction of the core metal is +45.
Degree and -45 degree were alternately wound, and the remaining six layers were wound at an angle of 0 degree.

After further winding a Teflon tape under tension and placing it in a heating furnace, the temperature was 280 ° C for 3 hours.
Heat at 0 minutes, cool and remove the core metal, length 119
A preform having a diameter of 0 mm, a large diameter of 18 mm, and a small diameter of 8 mm was obtained.

Next, the preform was mounted on a forming die 5 as shown in FIG. A total of 10 steps 7 are formed on the inner surface 6 of the mold 5.
… Are formed, and the change in outer diameter per stage is 0.3 m
m, and the gap between the steps 7 is 60 mm at the center and 43 mm at both ends.

A cover tube 11 made of Teflon is provided inside the preform 4.
, And both ends thereof were sealed in a mold 5.

Then, the mixture was placed in an autoclave, the pressure between the mold 5 and the preform 4 was reduced to about 10 ² kPa, the pressure in the autoclave was set to 1 MPa, and the temperature was set to 300 ° C.
After heating and pressurizing for hours, it was cooled.

The shaft thus obtained had a step formed on its outer surface and had a length of 1143 mm, a large diameter of 18.5 mm and a small diameter of 8.5 mm.

(Comparative Example) A prepreg tape was wound around a core metal under the same conditions as in the example, and a Teflon tape was wound and tightened, then housed in a split mold, and heated and pressed at a temperature of 280 ° C for 30 minutes. Thus, a shaft having a length of 1190 mm, a large diameter of 18 mm and a small diameter of 8 mm was obtained.

The shaft was horizontally supported at two points of 972 mm and 1107 mm from the small-diameter end of the shaft, a load of 2.7 kg was applied to a position 750 mm from the same end, and the amount of deflection at a point of 772 mm from the same end was measured.

Assuming that the amount of deflection of the shaft in the example is 100, the amount of deflection of the shaft in the comparative example is 110, and it was found that the bending rigidity of the shaft of the example was improved by about 10%.

〔The invention's effect〕

As described above, according to the present invention, the reinforcing fibers present in the thermoplastic resin as the matrix are in a tensioned state in which the reinforcing fibers are not loosened in both the radially outward direction and the axial direction, and the reinforcing fibers are reinforced. It is possible to manufacture a golf club shaft having high rigidity and exhibiting sufficient effects. Further, one or more steps are formed in the obtained golf club shaft, whereby the vibration attenuation is not too large, and the shot feeling becomes metallic.

[Brief description of the drawings]

1 to 4 are schematic cross-sectional views showing an example of the manufacturing method of the present invention in the order of steps. 1 ... core metal, 2 ... prepreg, 4 ... preformed body, 5 ... molding die, 7 ... step, 10 ... autoclave, 12 ... shaft.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) A63B 53/10

Claims (4)

(57) [Claims] 1. A prepreg made of a reinforcing fiber and a thermoplastic resin is wound around a core mold and heated and molded to obtain a cylindrical preform. Then, the preform is placed on the inner surface of the mold in one or more longitudinal directions. A method of manufacturing a shaft for a golf club, comprising: inserting a preform into a hollow cylindrical mold having a step formed therein; and applying heat from the inside to the outside of the preformed body while applying pressure. 2. The method for producing a golf club shaft according to claim 1, wherein the pressure between the preform and the mold is reduced while the pressure is increased. 3. A method according to claim 1, wherein a flexible tube is passed through the inside of the preform, the inner surface of the preform is covered with the tube, and pressure is applied through the tube. A method for producing the golf club shaft according to the above. 4. The method for producing a golf club shaft according to claim 1, wherein the thermoplastic resin has a heat distortion temperature of 140 ° C. or less.