JPH0673561B2 - Golf club head manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention forms a core part using a synthetic resin material as a core material,
The present invention relates to a method for manufacturing a golf club head in which the outer periphery of a core portion is coated with a resin material containing carbon reinforcing fibers to form the outer periphery.

[Conventional technology]

Recently, the appearance of two-piece balls has increased the impact force applied to the club head, and there has been an increasing demand for improving the strength of the striking surface (face surface). Therefore, a head using a carbon fiber reinforced plastic (hereinafter referred to as CFRP) material, a so-called carbon head, has been developed as a lightweight and high-strength material.

By the way, when a sheet molding compound (hereinafter referred to as SMC) is used as the CFRP material, an unsaturated polyester resin is generally used because it is easy to handle (thickening rate) and low in cost.

However, the unsaturated polyester resin is not only poor in adhesiveness but also poor in toughness, and also has irregularities on the surface due to curing shrinkage, and has a drawback that the number of work steps for adjusting the shape by post-processing is high.

Therefore, as described in JP-A-59-101168, an attempt was made to eliminate the drawbacks of unsaturated polyester by using a synthetic resin of epoxy resin or ABS resin, carbon fiber, a filler and a curing agent as the material of the outer layer. Things were developed. The golf club head described in Japanese Utility Model Publication No. 59-193454 also comprises a thermosetting resin containing carbon fibers and microballoons, for example, a composite material of vinyl ester resin, and eliminates the drawbacks of unsaturated polyester. ing.

However, in the former conventional example, the specific gravity of the inner core body is 0.9.
Below, the surface of the inner core body is configured to have an inner core, which is previously coated with a synthetic resin, inside the outer layer material, and the outer layer material is set with the inner core of the softened raw material. It is molded by pushing it into the mold. Since the epoxy resin has a synthetic resin coating the surface of the inner core body, the epoxy resin is prevented from being impregnated into the inner core body. When SMC is used as the outer layer material, the SMC is coated around the inner core body and this is heated and pressed, but since the inner core body remains hollow, the inner core body and its surroundings will be covered if the pressure is increased. There was a risk that the layers would be deformed or damaged. If the inner core body is made thicker to increase the strength, an increase in weight cannot be avoided. In the former conventional example,
It is lightweight and disadvantageous in terms of increasing the size of the head, and since the outer layer material is also injection or extrusion molded, it is difficult to make the carbon fiber length longer than SMC (there is a problem of variation due to mixing). In terms of strength, SMC that can use long fibers is superior. Even if SMC was used as the outer layer material, the inner core body was not designed to sufficiently withstand the pressure at the time of pressurization.

The latter conventional example does not include the inner core body like the former,
The head body is made thicker, and if necessary, a lightweight member is used as a core material, or a space area is provided inside, but since the head body does not use SMC, SMC is Nothing is addressed to the problem of heating and pressurizing.

[Problems to be solved]

Conventional golf club heads are more resistant to impact and superior in hitting control, even if the defects of vinyl ester resin or epoxy resin or unsaturated polyester resin can be eliminated. It wasn't enough yet. So, this invention
An object of the present invention is to provide a method for manufacturing a golf club head which is excellent in impact resistance and hit control.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention comprises a face part on the ball hit part side, a hitting part located on the center part side of the face part, and a base part connected to the face part and including a bottom side region. As a whole, a hollow core is molded from a synthetic resin in the shape of a bowl with an upper surface opening, and the hollow part of this core is foamed and filled with a filler to form a filled part, and at least the hitting part of the core is removed. The outer peripheral portion including the side peripheral side and the upper surface side is formed by heating and pressing SMC in which carbon fiber is mixed with vinyl ester resin or epoxy resin.

〔Example〕

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a cross section of a golf club head according to the present invention. The main body 1 of the golf club head is
It is composed of a core portion 2, a filling portion 3 formed by filling a hollow portion of the core portion 2 with a filler, and an outer peripheral portion 4 formed around the core portion 2 by SMC.

The core portion 2 is located on the lateral side in FIG. 2 and is a face portion 2a on the ball hit portion side and a face portion 2a.
Hitting area 2b located on the center side and serving as a ball hit area
And a base portion 2c which is connected to the face portion 2a and includes a bottom surface side region. And especially the hit part 2b
Is molded using a prepreg composed of a carbon fiber woven fabric and a vinyl ester resin, it is resistant to impact and has high surface smoothness.

The filling part 3 is foamed using a lightweight resin material such as urethane foam.

The outer peripheral portion 4 is formed by using a vinyl ester resin, has a strong adhesive force with the core portion 2 and has toughness, and prevents peeling or damage due to impact force over a long period of time. Has become.

Next, description will be made on how such a golf club head is manufactured.

First, the core portion 2 is molded with a resin material, but the impact portion 2b is insert-molded when the core portion 2 is molded. FIG. 2 shows a molded product of the core portion 2 in which the hitting portion 2b is inserted. The hitting portion 2b constitutes a part of the outer shell of the golf club head after completion and covers the core portion 2. Since a certain strength is required for the hitting portion 2b, a high strength type CFRP is used. For example, in this embodiment, carbon fiber woven fabric (# 6142 manufactured by Toray Industries, Inc.) is used as a vinyl ester resin (Takeda Pharmaceutical Co., Ltd.). P-313) manufactured by Co., Ltd. was impregnated and the fiber content (Wf) by weight was adjusted to 40 to 60% (prepreg).

As shown in FIGS. 3 to 5, the molding of the core portion 2 having the hitting portion 2b is performed by the first mold of the upper and lower split molds, that is, the first mold.
It is molded using the upper mold 5 and the first lower mold 6. First upper mold 5
As shown in FIG. 4, the core portion 2 is provided with a concave portion 7a and a convex portion 8 for molding the rib 7, and the presence of the convex portion 8 enables the hollow portion 9 to be molded in the core portion 2. . First lower mold 6
Is a recess 10 into which a member forming the striking portion 2b is inserted.
And a shaft insertion recess or protrusion 11. Recess
The cavity of the first lower mold 6 including 10 is a replaceable mounting piece.
It is composed of 10A. Therefore, by simply inserting the placement piece 10A corresponding to the shape and size of the hitting portion 2b into a predetermined portion of the first lower mold 6, the hitting portion 2b of various shapes and sizes can be easily insert-molded. Further, a convex portion (not shown) for molding the weight adjusting boss 12 and other irregularities for molding other necessary projections or depressions can be freely provided on the bottom of the first lower mold 6. .

SMC is put into the first upper and lower molds 5 and 6 and both molds 5 and 6 are closed and heated (the mold temperature is 120 to 160 ° C, preferably 130 to 140 ° C).
℃) and pressurize (20 to 300 kg / mm ² mold clamping pressure),
After the lapse of about 2 to 5 minutes, the upper and lower molds 5 and 6 are separated again to form the core portion 2 having the hollow portion 9 and the rib 7.

In this way, when the core portion 2 in which the hitting portion 2b is inserted is molded by the first upper and lower molds 5 and 6, the lightweight resin material is foamed in the hollow portion 9 so that the filler 13 is filled in the hollow portion 9. (See FIG. 6). At this time, a shaft (not shown) is provided in the foam mold and the pin insertion hole is formed in advance. As the filler 13, a so-called master batch consisting of polyol: 100 parts by weight, foam stabilizer: 1 part by weight, catalyst: 0.5 parts by weight, water: 0.5 parts by weight and a curing agent (112 parts by weight) and 1
Mix for about 5 seconds, put in a foam mold that has been heated to 50 ° C beforehand, and cure in an oven at 50 ° C for about 15 to 20 minutes.
The specific gravity of the filling portion 3 foam-molded in this way is 0.25 to
It was about 0.50.

Next, the SMC 20 is attached so as to wrap around the outer periphery including the side peripheral side excluding at least the hitting portion 2b and the upper surface side (the upper surface of the filling portion 3) of the core portion 2 of the second upper and lower molds 14 and 15 Two
Set in lower mold 15. In FIG. 7, the SMC 20 is placed on the filling material 13, but the SMC 20 is attached to the whole as is conventionally done. At this time, the hosel part into which the shaft is inserted is also molded with SMC20. For this SMC20,
For example, as a synthetic resin, a vinyl ester resin (including a thickener and a peroxide catalyst) is mixed at a weight ratio of 55,
The carbon fiber mixed was set to 45 weight ratio. in this way,
Since the outer peripheral portion 4 (described later) formed from the SMC 20 covers the side peripheral side and the upper surface side of the face portion 2a (excluding the hitting portion 2b) and the base portion 2c of the core portion 2, the club head outer peripheral side is reinforced fiber. It is molded from a vinyl ester resin material mixed with. In this embodiment, the vinyl ester resin is used as the resin material used, but an epoxy resin is also possible. Further, the carbon fiber used in the outer peripheral portion 4 is preferably a high strength type.

The second lower mold 15 is provided with a mounting piece 16A. This table piece 1
6A also has the same function as the placement piece 10A in the first lower mold 6. The second upper mold 14 is provided with a shaft pin 18 that is inserted into a pin insertion hole 17 provided in the filling material 13.
The tip of 18 penetrates the core 2 and is inserted into the hole 19 of the second lower mold 15. In this way, the second upper and lower molds 14 and 15 are heated and pressed to manufacture a golf club head.

In this embodiment, a vinyl ester resin is used for the outer peripheral portion 4, but a comparison experiment is performed between the adhesive force of this vinyl ester resin and the adhesive force of an unsaturated polyester resin which has been generally used conventionally. As a result, the data shown in Table 1 were obtained.

In these experiments, carbon fiber woven fabric (# 6142 manufactured by Toray Industries, Inc.) was commonly used, and the adhesive force with each prepreg formed by impregnating each of these with the synthetic resin was measured by the flat synthetic resin. The molding conditions for the flat plate were heating and pressurizing at 140 ° C. for 5 minutes.

Also, in order to check the surface smoothness of molded products of each synthetic resin,
The unevenness of the surface was investigated by two-dimensional measurement for the molded products of each synthetic resin molded flat under the same conditions.
Table-like data were obtained.

As is apparent from such experimental data, it is understood that the molded product of the vinyl ester resin is far superior in adhesive strength and surface smoothness to the unsaturated polyester resin.

That is, it is considered that since the vinyl ester SMC is thickened by the isocyanate, the bond is hard to be broken, the resin flows to flow the fibers, and the uniform surface composition distribution is maintained, so that the surface smoothness is good. On the other hand, regarding surface smoothness, since the viscosity of unsaturated polyester SMC is increased by using magnesium oxide (MgO), the loose bond with the resin by the thickener is broken at a relatively low temperature, resulting in a resin viscosity It is thought that this is due to the extreme decrease in flow rate and the flow of only the resin to cause separation and shrinkage from the carbon fiber.

Incidentally, in the case of an epoxy resin, the fluidity at the time of press molding can be controlled without losing the adhesiveness by selecting the condition of B-stage, and therefore, the surface smoothness is as high as that of the vinyl ester resin. A molded product can be obtained. Further, in the case of this epoxy resin, the toughness is at the same level as that of the vinyl ester resin, and the performance as a head is satisfied, but since the adhesiveness with a metal is high, the releasability is poor.

Further, even if the thickness of the core portion 2 is thin and light, the hollow portion 9 is filled with the foamed filler material 13, so that the outer periphery is surrounded.
Even if the SMC is attached and heated and pressed, the core material (core portion 2 and filling portion 3) is not deformed or damaged. It is relatively easy to manufacture a large core and a large head as a whole, and even if the head is large, it is possible to avoid an increase in weight. That is, even if the volume of the foamed filler 13 is increased, the core 2 may be thin,
Since the outer peripheral portion 4 is also made of SMC20 and has sufficient strength, it is not necessary to increase the wall thickness, and it is large and lightweight and has excellent impact resistance as a whole. If the head is enlarged, the sweet area is expanded and the depth of the center of gravity can be increased.

〔effect〕

As described above, the golf club head manufactured according to the present invention uses SMC in which carbon fiber is mixed with vinyl ester resin or epoxy resin having excellent adhesive strength and surface smoothness as the synthetic resin of the outer peripheral portion. As a result, the strength and toughness required for the head can be remarkably enhanced to improve the durability, and the appearance can be enhanced. In particular, SMC molding requires a core material that can sufficiently withstand the applied pressure because it is heated and pressed, but in this invention, since it is a core material that contains a foamed filler in the hollow part of the core part, it is light Even a large core material can withstand a sufficient pressure, and SMC can be accurately molded on the outer periphery of the core material. As a result, it is possible to mold the outer peripheral portion formed from SMC, which is far superior in strength in comparison with the one obtained by injection or extrusion molding of a molten resin mixed with carbon fibers, and it is possible to reduce the wall thickness. Therefore, it is possible to increase the size and weight of the head, and it is also easy to expand the sweet area and increase the depth of the center of gravity. Therefore, the batting controllability is also excellent.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a molded product of a golf club head manufactured according to the present invention, FIG. 2 is a schematic perspective view of a core portion in which a hitting portion is inserted, and FIG. 3 is a core by a first upper and lower molds. FIG. 4 is a schematic bottom view of the first upper mold, FIG. 5 is a schematic plan view of the base portion of the core portion, and FIG. 6 is a filler material for the core portion. FIG. 7 is a schematic perspective view of a filled state, and FIG. 7 is a schematic perspective view showing a preparatory step of molding the outer peripheral portion. 1 …… Main body, 2 …… Core part, 2a …… Face part, 2b ……
Hitting part, 2c ... base part, 3 ... filling part, 4 ... outer peripheral part, 13 ... filling material.

Claims (1)

[Claims] 1. A face portion (2
a), a striking part (2b) located on the center side of the face part (2a), and a base part (2c) that is connected to the face part (2a) and includes a bottom side region. A hollow core part (2) is molded into a bowl shape from a synthetic resin, and the hollow part (9) of the core part (2) is foamed and filled with a filling material (13) to form a filling part (3). The outer peripheral portion (4) including at least the side peripheral side and the upper surface side of the core portion (2) excluding the hitting portion (2b) is molded by heating and pressing SMC in which carbon fiber is mixed with vinyl ester resin or epoxy resin. A method for manufacturing a golf club head, comprising: