JPH07204300A - Golf club head and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a golf club head of high strength containing reinforcing fiber of large fiber effective length by forming at least a part of a shell out of thermoplastic resin containing the reinforcing fiber, and specifying a value for the mode of a ratio of fiber effective length to the natural length of the reinforcing fiber. CONSTITUTION:Thermoplastic resin 12 containing reinforcing fiber of 6mm or longer fiber natural length is housed in the pot 14 of a transfer molding machine 10. Then, the resin 12 is heated, for example, to 350 deg.C for softening on the operation of a heater 16, and extruded into a mold 22 with a plunger 28. After the resin 12 is cooled and solidified in a cavity 26, the mold 22 is opened and a compact 30 used as a golf club head shell is taken out. In this case, the mode of a ratio of fiber effective length to reinforcing fiber natural length in the compact 30 of the golf club head is taken at 0.8 or more. The golf club head so molded has a high strength improvement effect due to a lint contained in the plastic 12. Thus, the weight thereof becomes small and a high degree of freedom for design can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a golf club head and a method for manufacturing the same, and particularly to a golf club head made of a synthetic resin having an increased strength.

[0002]

2. Description of the Related Art Conventionally, golf club heads made of Persimmon or made of metal such as stainless steel and aluminum alloy have been known. However,
The Persimmon golf club head cannot be modified in bending and shaping by post-processing, and the metal golf club head has problems such as a large weight and a low degree of freedom in design. Therefore, in recent years, golf club heads made of fiber reinforced plastic have been developed.
As a golf club head made of fiber reinforced plastic, for example, a thermosetting synthetic resin is used as a matrix resin, and glass fiber or carbon fiber having a length of 6 to 20 mm is added to the fiber reinforced plastic (hereinafter referred to as FRP). There is one using.

[0003]

However, the above-mentioned F
In the case of molding by RP, the viscosity at the time of molding is low, the reinforcing fiber does not expand when the resin is press-fitted and moved into the mold, and the resin is cured in a state where the fiber is bent,
As the fibers are bent, the effective fiber length of the reinforcing fibers becomes shorter. Therefore, the strength of the molded article could not be efficiently increased because the length of the reinforcing fiber was short. Therefore, in order to increase the strength, it is necessary to take measures such as adding an excessive amount of reinforcing fibers or increasing the wall thickness of the molded body. However, if the addition amount of the reinforcing fiber is excessive, the weight of the molded body increases, and in addition to the increase in the weight of the molded body, there is a problem that the degree of freedom in design decreases. Further, when the amount of the reinforcing fiber is increased, there is a problem that the moldability is deteriorated and the yield is reduced. Further, when the matrix resin is a thermosetting resin, it takes a long time to cure, which hinders the reduction of the molding time.

In order to solve the above-mentioned problems, the inventors of the present invention have used a fiber reinforced thermoplastic resin (hereinafter referred to as FRT) in which a thermoplastic resin is used as a matrix resin and reinforcing fibers are added to the matrix resin.
Call P. ) Was used to manufacture a golf club head by injection molding. If it is a thermoplastic resin,
This is because not only the curing time is short, but also the viscosity at the time of molding is relatively high and the bending of the reinforcing fiber is small. However, when the FRTP is injection-molded, the reinforcing fiber is cut or bent by the screw for injecting the resin, and even if the long-fiber reinforcing fiber is used, the effect of the reinforcing fiber in the molded body is increased. The length was shortened and the strength was also insufficient.

The present invention has been made to solve the above problems, and provides a high-strength golf club head containing reinforcing fibers having a long effective fiber length, and a method for manufacturing the same.

[0006]

In the golf club head of the present invention, at least part of the outer shell is made of a thermoplastic resin containing reinforcing fibers, and the ratio of the effective fiber length to the natural length of the reinforcing fibers is high. The most frequent value of is 0.8 or more.

The golf club head manufacturing method of the present invention comprises molding at least a part of the outer shell by a transfer molding method using a thermoplastic resin containing long fibers having a length of 6 mm or more as pellets. It is a feature.

In the present invention, the natural fiber length of the reinforcing fiber in the resin is the length l ₀ of the expanded fiber F as shown in FIG. 2A, and the effective fiber length is 2 is the actual length of the reinforcing fiber present in the molded body after molding, and as shown in FIG. 2 (b), if the fiber F is in a bent state, the distance l from one end to the other end , Or if the fiber is cut somehow, it means the length of the fiber after the cutting.

[0009]

According to the method of manufacturing the golf club head of the present invention, at least a part of the outer shell of the golf club head is molded by the transfer molding method by using the thermoplastic resin containing long fibers having a length of 6 mm or more as pellets. With this method, it is possible to reduce that the reinforcing fiber in the thermoplastic resin is molded in a bent state, and further, unlike the injection molding method at the time of molding, screw etc. Since it is not used, the reinforcing fiber is not cut, and the thermoplastic resin can be molded while maintaining the length of the mixed long fiber. Therefore, according to this method, the substantial length of the reinforcing fiber in the molded body (fiber effective length:
It is possible to approach the length (natural length: l ₀ ) of the fiber when (l) is mixed with the thermoplastic resin, and in particular its mode value is set to 0.
It is possible to set it to 8 or more. By setting the mode of the ratio of the effective fiber length to the natural length of the reinforcing fibers in the molded body to 0.8 or more, the strength of the molded body can be remarkably increased and an excellent golf club head can be obtained. You can

In the present invention, the thermoplastic resin includes polycarbonate, polyamide (nylon 6, nylon 6).
6, nylon 11), polybutylene terephthalate, polyoxymethylene (acetal resin), polyphenylene sulfide, modified polyphenylene sulfide, modified polyphenylene oxide, polyether ether ketone, polyether sulfane, polyether imide, liquid crystal polymer (semi-aromatic) A group polyester, a liquid crystal polyester having a wholly aromatic polyester as a basic structure), or a thermoplastic polyimide can be applied. Above all, the heat distortion temperature (ASTM D648, 18.6 kg / cm ² ) is 140
Those below ℃ are preferred. These may be used alone or may be a blend polymer of two or more kinds.

Further, carbon fiber, glass fiber, aramid fiber, boron fiber, amorphous metal fiber and the like can be applied to the reinforcing fiber mixed in the thermoplastic resin in the present invention. Further, these fibers may be used alone or in combination of two or more kinds.

The length of the reinforcing fiber must be 6 mm or more. This is because if it is less than 6 mm, the reinforcing fiber has a small effect of improving strength. The length of the reinforcing fiber is 30.
It is preferably mm or less. This is because if it is 30 mm or more, defective parts such as welds and voids are likely to occur in the molded product, and the yield is reduced.

The thickness and shape of the reinforcing fiber are not particularly limited, and roving, roving cloth, chopped strand, chopped strand mat, etc. can be applied.

The content of the reinforcing fiber in the matrix resin which is a thermoplastic resin is preferably in the range of 10 to 60% by volume. If it is less than this range, a sufficient reinforcing effect cannot be obtained, and if it is more than this range, voids due to resin non-impregnation or the like are likely to occur in the molded product, and the yield decreases. Further, in order to improve the yield, high temperature and high pressure are required, which lowers the productivity and increases the cost of the mold.

The present invention may be applied to all of the outer shell of a golf club head, but may be applied to at least a portion of the outer shell. For example, the golf club head may be manufactured by molding only the face surface of the golf club head with the FRTP of the present invention, molding other portions (sole, crown, etc.) with the FRP, and joining them.

[0016]

EXAMPLE An example of the present invention will be described below. The golf club head of the present invention is manufactured using a transfer molding method. For example, a transfer molding machine 10 as shown in FIG. 1 can be used. Transfer molding machine 1
The reference numeral 0 generally includes a mold portion 22, a pot 14, and a plunger 28. The mold 22 has a cavity 26 having the shape of a golf club head, and in this example, a matching piece 24 is arranged. The pot 14 is connected to the mold 22 and stores the resin 12 to be injected into the cavity 26 before molding, and includes a heater 16. The plunger 28 uses the resin in the pot 14 for the cavity 2 of the mold 22.
It pushes to 6. In FIG. 1, reference numeral 18 is a shutter that shields the cavity 26 of the mold 22 and the pot 14, and reference numeral 20 is a heat insulating material.

To carry out transfer molding, first, a thermoplastic resin containing reinforcing fibers is stored in a pot 14 of the transfer molding machine 10. At this time, the pot 14
Store only the amount necessary for molding the golf club head to be molded. The length of the reinforcing fiber (natural fiber length) is 6
mm or more. Here, one in which polycarbonate is used as the matrix resin and carbon fibers are mixed as the reinforcing fibers is taken as an example. In this embodiment, the content of carbon fiber is set to 30% (volume ratio), and 150 g in the pot.
I had it stored. Thermoplastic resin 1 stored in the pot 14
2 is heated to 350 ° C. by the heater 16 and softened. When the thermoplastic resin 12 is heated to the set temperature, the plunger 28 is used to push the thermoplastic resin 12 into the mold 22.
Push it out. The extrusion rate was 50 mm / min and 40 kg / cm ^2, and it was held for 10 seconds. At this time, the mold 22 is 120
It was kept warm at ℃. Then, when the resin is completely cooled and solidified in the cavity 26, the mold 22 is opened, and the molded body 30 serving as the outer shell of the golf club head is taken out. By molding in this manner, the mode of the ratio of the effective fiber length to the natural length of the reinforcing fiber in the molded body 30 of the golf club head is 0.8.
The above can be done.

The above method uses a mold having a cavity in the shape of a golf club head and integrally molds the golf club head by transfer molding. Next, the golf club molded by the above method is used. An example of molding a partial material of the outer shell of the head and manufacturing a golf club head from the partial material will be described with reference to FIGS. First, the face 32, the sole 34, and the crown 36, which are partial members of the golf club head, are molded by the transfer molding method. A through hole 38 for pressurizing the inside of the head is formed at an arbitrary position of the sole 13 as described later. As shown in FIG. 6, the partial materials such as the face 32, the sole 34, and the crown 36 are
It is installed in the mold 40 in the assembled state. The molding die 40 has a cavity in the shape of a golf club head, and a fluid injection port 42 is formed therein. Further, a cover balloon 44 made of a silicone resin or the like is inserted inside the partial material. The mouth of the cover balloon 44 is connected to a pressurizing device (not shown) through the through hole 38 of the partial material and the fluid injection port 42 of the molding die 40, and the die 40 is stored in a vacuum heating device. In this state, the inside of the vacuum heating device is evacuated to reduce the pressure in the gap between each part material and the molding die 40, and also heated, and a pressurized medium such as nitrogen gas is introduced into the cover balloon 44 from the pressurizing device. , Increase the internal pressure. By doing so, the respective partial materials are integrated and molded into a shape along the cavity of the molding die 40,
After cooling and solidification, the molded product is released from the mold and the cover balloon is pulled out, whereby the golf club head is manufactured.

[Distribution test] A golf club head manufactured by transfer molding using the above fiber reinforced thermoplastic resin, a golf club head molded by the injection molding method using the same fiber reinforced thermoplastic resin, of the same quality and quantity. Reinforcing fibers in each molded body of the golf club head molded by the transfer molding method as a pellet fiber-reinforced thermosetting resin containing a reinforcing fiber in a thermosetting resin,
The ratio of the effective fiber length to the natural length was measured and its distribution was investigated. The measurement result is shown in FIG. From FIG. 3, it can be seen that the fiber produced by the transfer molding method using FRTP, which corresponds to this example, has a ratio (l / l) of the effective fiber length (l) to the natural length (l ₀ ) of the reinforcing fiber. The mode value of ₀ ) is 0.86, and the distribution of the ratio (l / l ₀ ) is summarized, and it is clear that most of them are 0.8 or more. On the other hand, in the case of injection molding using the same FRTP, the distribution of the ratio (l / l ₀ ) is widened and the mode value is 0.71. This is probably because the reinforcing fiber was cut by the screw during injection molding, and even if long fiber reinforcing fiber was used, the fiber length of the reinforcing fiber in the molded body was shortened. It is inevitable in law. Furthermore, in injection molding,
It is necessary to reduce the resin viscosity of the matrix resin, which also increases the bending ratio of the reinforcing fiber. Also,
In the case of transfer molding using FRP, the distribution of the ratio (l / l ₀ ) spreads and the mode value was 0.7.
It is 6. This is because the FRP has a low viscosity, and when the resin is press-fitted and moved into the mold, the reinforcing fiber does not expand and the resin is cured in a bent state, and the effective fiber length becomes short. I think it's gone.

[Strength Test] Polycarbonate is used as a thermoplastic resin, and natural length (l ₀ ) in the reinforcing fiber is used.
The relationship between the ratio (1 / l ₀ ) of the effective fiber length (l) to the fiber and the strength was tested. In the test, the strength of 1 (r / l ₀ ) was set as 1, and the strength of several kinds of ratio (l / l ₀ ) in the range of 0.1 to 0.95 was measured. , Ratio (l /
l ₀ ) is a relative comparison with one. The strength was measured by fixing the golf club head with a resin fixing jig, and fixing the center part of the crown with an iron ball indenter (5
R) is the maximum load when pressed (5 mm / min). The test results are shown in FIG. From FIG. 4, the ratio (l /
As the mode of l ₀ ) increases, the strength increases,
In particular, it can be seen that the strength increases critically when the ratio (l / l ₀ ) exceeds 0.8. Therefore, from the test results shown in FIG. 3 and FIG. 4, the golf club head of this example in which FRTP was molded by the transfer molding method was obtained by molding FRTP by the injection molding method or FRP by the transfer molding method. It can be seen that the strength is dramatically increased compared to the molded product.

[0021]

In the golf club head of the present invention, at least a part of the outer shell is made of a thermoplastic resin containing a reinforcing fiber, and the mode of the ratio of the effective fiber length to the natural length of the reinforcing fiber is the mode. Is 0.8 or more. This golf club head has at least a part of its outer shell molded by a transfer molding method using a thermoplastic resin containing long fibers as pellets. Manufactured by. The golf club head according to the present invention has a high strength-improving effect due to the long fibers contained in the thermoplastic resin constituting the golf club head, is light in weight, has a high degree of freedom in design, and effectively utilizes the long fibers. To realize a golf club head having improved strength. Further, according to the present invention, since the amount of reinforcing fibers mixed in the thermoplastic resin can be reduced, the moldability is good and the manufacturing yield is high while maintaining the weight reduction of the golf club head.

[Brief description of drawings]

FIG. 1 is a schematic view showing a molding method of this example.

FIG. 2 (a) is a schematic diagram for explaining a natural fiber length of a reinforcing fiber, and FIG. 2 (b) is a schematic diagram for explaining an effective fiber length.

FIG. 3 is a distribution diagram of a ratio (l / l ₀ ) of reinforcing fibers in a molded body.

FIG. 4 is a graph showing a relationship between a ratio (l / l ₀ ) and strength.

FIG. 5 is a perspective view showing a partial member of a golf club head.

FIG. 6 is a side sectional view showing a method of molding a golf club head.

[Explanation of symbols]

10 ... Transfer molding machine, 12 ... Thermoplastic resin,
14 ... Pot, 22 ... Mold, 28 ... Plunger, 3
0: molded body, F: reinforcing fiber, l: effective fiber length, l ₀ ...
・ Natural fiber length

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area B29K 105: 08

Claims (2)

[Claims] 1. At least a part of the outer shell is made of a thermoplastic resin containing a reinforcing fiber, and the mode of the ratio of the effective fiber length to the natural length in the reinforcing fiber is 0.8 or more. A characteristic golf club head. 2. A method for manufacturing a golf club head, characterized in that at least a part of an outer shell is molded by a transfer molding method using a thermoplastic resin containing long fibers having a length of 6 mm or more as pellets. .