JPH0824377A - Golf club head manufacturing method - Google Patents

Abstract

PURPOSE:To easily produce a golf club head which is hollow and has a dense outside shell without forming a core part by laminating prepreg consisting of carbon fibers on the outer peripheral surface of a rubber bag for internal pressure and setting the prepreg into a metal mold and curing the thermosetting resin of the prepreg. CONSTITUTION:A pipe 2 as a mouthpiece for molding is first inserted into an air injection port part 1b of the rubber bag 1 for internal pressure which is expandable into a shape approximate to the internal shape of the desired hollow head at the time of production. Next, air is injected from the air injection port part 1b via the pipe 2 into the rubber bag 1 for internal pressure to expand its expanding part 1a and the outer peripheral surface thereof is coated with the prepreg 3 consisting of carbon fibers in several layers. In succession, the prepreg 3 which is laminated is set into the metal mold 4 and thereafter, the internal pressure is applied on the inside of the rubber bag 1 for internal pressure through the air injection port part 1b from the pipe 2. The thermosetting resin of the prepreg 3 is then cured by executing heating and press molding, and the hollow head is completed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a golf club head having an outer shell made of carbon fiber and having a hollow inner shell.

[0002]

2. Description of the Related Art Conventionally, the head of a wood club has been traditionally formed from a single material of persimmon (persimmon tree) that is lightweight and has relatively high strength, but problems such as difficulty in obtaining the material and molding cost are involved. From hard synthetic resin heads to metal casting heads such as steel. However, since it has a larger specific gravity than Persimmon, it is necessary to reduce the wall thickness to form a hollow inside in order to make it about the same size as a conventional head. There is a risk of insufficient strength.

In the former synthetic resin head, it has been attempted to use short fibers of glass or carbon graphite in order to increase the strength, but it cannot be said that reinforcement hardening is sufficient because of the short fibers. The head may still be cracked or chipped, and it has not been put to practical use. Therefore, at present, long fibers such as carbon are used as reinforcing fibers,
Heads made by binding this with resin are becoming mainstream along with metal heads.

Conventionally, as a method of manufacturing a golf club head of this type, for example, a core formed of hard styrofoam is fixed in a mold, and 50 carbon long fibers and uncured thermosetting are provided on the outer periphery of the core in the mold. There is a method in which a carbon resin formed by mixing in a ratio of the volatile resin 50 is manually packed and heat-molded. However, in such a golf club head manufacturing method, since it is not possible to tightly fill the carbon fiber between the core and the mold, it is not possible to hit a golf ball with a club head molded by such a method. In addition, the inner core may move inside the outer shell, which makes accurate shots impossible.

In view of this point, the applicant of the present invention has disclosed in Japanese Patent Application Laid-Open No. 59-59
In Japanese Patent No. 49784, high-density urethane foam is pressure-injected into a mold to form a core having a predetermined three-dimensional shape, and a prepreg of glass fiber (an uncured resin on the fiber is formed on the entire outer circumference of the core. (Impregnated) are laminated for several layers to cover the core portion, and the outer periphery of the glass fiber prepreg is covered for several layers with a prepreg of carbon fiber serving as an outer shell. A face plate formed in advance by laminating a carbon fiber prepreg on the face surface portion of a carbon fiber prepreg forming an outer shell is attached, and after inserting these into a molding die, the die is clamped and heated. Discloses a method for manufacturing a golf club head in which a thermosetting resin inside is integrally cured. According to this method, the outer periphery of the core can be densely covered with the reinforcing fiber, and the content of the reinforcing fiber can be increased.

[0006]

However, it takes time to manufacture the core portion having the same shape. That is, it is necessary to inject a high-density urethane foam into a mold designed to a predetermined size under pressure to produce a core portion, which is not easy to produce.
The cost is also high.

The presence of the core portion in the golf club head means that the golf club head is heavier than that having a hollow outer shell,
The result is the same as the increase in specific gravity, which is a factor limiting the freedom of design. In particular, since metal heads have recently tended to increase the volume by using high-strength titanium or titanium alloy as a material, carbon heads are also used from the viewpoint of ease of hitting, including a stable appearance. A head having a larger size than before has been desired, but the head having a core has a limitation in increasing the size.

The present invention has been made in view of the above problems, and it is possible to manufacture a golf club head made of a carbon fiber having a hollow outer shell and a dense outer shell without the need to form the core portion, and the desired size can be easily obtained. It is an object of the present invention to provide a method for manufacturing a golf club head, which is capable of obtaining a golf club head having high strength and strength.

[0009]

In order to achieve the above object, a method of manufacturing a golf club head according to the present invention comprises a carbon fiber prepreg on the outer peripheral surface of an internal pressure rubber bag which is inflated to approximate the internal shape of the head. And the rubber bag is covered and inserted into the molding die and set, and then the die is clamped, and the internal pressure of the rubber bag is increased by increasing the internal pressure of the rubber bag. The thermosetting resin is integrally cured.

[0010]

Since a rubber bag is used in place of the conventional core and is covered with a prepreg of carbon fiber, it is not necessary to prepare and prepare the core by a labor-intensive method as in the conventional case. Therefore, a golf club head having a hollow inside and no core is easily obtained.

Further, since the rubber bag covered with the carbon fiber is put in a molding die and is molded by the mold while increasing the internal pressure of the rubber bag, the carbon fiber is applied to the inner wall of the mold by the internal pressure. The prepreg laminating work can be simplified because the intermediate molded product in a pressed state can be pressed to form a dense outer shell and strict dimensional accuracy is not required.

Further, since the weight is reduced by the amount that the inside is hollow and there is no core, the degree of freedom in design can be increased by increasing the volume of the head accordingly.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

In the method of the present invention, first, as shown in FIG. 1, an internal pressure rubber bag 1 that can be inflated to a desired internal shape of the hollow head (a shape smaller by the outer shell) is prepared. The rubber bag 1 for internal pressure is provided with an inflating portion 1a capable of inflating to the inner shape of the head and an air injecting portion 1b, and the air injecting portion 1b extends relatively long from one place of the inflating portion 1a. There is. The internal pressure rubber bag 1 may be any one as long as it can be inflated into a shape similar to the internal shape of the head by injecting air, and for example, a commercially available rubber balloon or the like can be used. Next, a pipe 2 is prepared as a molding die to be installed on the heel side of the head at the time of molding a head, which will be described later, and the air inlet port 1b of the rubber bag 1 for internal pressure is inserted into the inside of the pipe 2.

In this state, air is injected from the air inlet port 1b through the pipe 2 to inflate the inflating part 1a of the internal pressure rubber bag 1. The shape of the expanded portion 1a at this stage is
It does not have to be the same as or similar to the internal shape of the head to be the final molded product, and it is sufficient if the expansion is roughly the same.

Next, the outer peripheral surface of the inflating portion 1a of the rubber bag for internal pressure 1 inflated to an approximate shape of the internal shape of the head, and the outer peripheral surface of the lower portion of the pipe 2 located outside the air inlet port 1b. Then, a long carbon fiber is wound as a material for the head and formed into a shape similar to the final molded product. Specifically, a carbon fiber prepreg 3 cut into small pieces of a predetermined size is coated over several layers so as to wrap the outer peripheral surface of the internal pressure rubber bag 1. The number of layers of the prepreg 3 required for this coating is, for example, as shown in FIG. 2, 6 pieces (thickness 2 mm) on the instep portion of the head, 15 pieces (thickness 5 mm) on the sole portion, and 26 pieces (thickness on the face portion). 6.5m
m), and the front and rear impact resistance is increased by making the front and rear parts denser than the upper and lower parts. The content of the thermosetting resin (epoxy resin) in the prepreg 3 of this carbon fiber is 35 to 40%, and most preferably about 37%. The end portion of the pipe 2 is sealed so that the rubber bag 1 does not shrink during the prepreg laminating operation.

The carbon fiber prepreg 3 constitutes the outer shell of the golf club head including the hosel, and the reason that the number of laminated layers is not proportional to the wall thickness is that materials of different thickness are used together.

The face portion may be integrated with a face plate formed beforehand of carbon resin, for example, a prepreg of carbon fibers laminated in about 20 layers and formed in advance, by attachment.

Then, as described above, the prepreg 3 of the carbon fiber forming the outer shell is laminated and inserted into the molding die (split die) 4 as shown in FIG. Then, after the mold is clamped, the air injection port portion 1 is inserted from the pipe 2 which is the molding die.
A higher internal pressure P is applied to the inside of the rubber bag 1 via b, that is, the air pressure inside the rubber bag 1 for internal pressure is increased. Due to this increase in internal pressure, the rubber bag 1 for internal pressure tends to expand toward the inner surface of the mold, as indicated by the arrow in FIG. Therefore, the prepreg 3 of carbon fiber wound around the outer peripheral surface of the rubber bag 1 for internal pressure is pressed by the internal pressure to form a dense carbon fiber layer, and the shape of the carbon fiber layer becomes a final molded product. It will be a perfect match to the external shape of the head.

After that, while applying the above-mentioned internal pressure P, the molding die 4 performs heating and pressure molding for a predetermined time. As a result, the thermosetting resin in the prepreg 3 made of carbon fiber is hardened, and a hollow golf club head in which the outer shell is formed tightly and integrally with the reinforcing fiber is obtained. The rubber bag 1 for internal pressure and the pipe 2 are preferably removed after the heating / pressurizing from the viewpoint of weight reduction, but since the weight increase by the former is slight, they may be left inside the head as they are.

When using a metal sole plate that is usually found in wood clubs, the plate is placed on the sole portion when it is set in the mold, and is integrated with the outer shell portion during heating and pressure molding. It may be made into a resin, or may be fixed with a screw after molding.

According to the above-described embodiment, in the manufacturing process of the golf club head, a golf club having a hollow outer shell and no core portion is required without preparing and preparing a core portion which has conventionally been troublesome to produce. The head can be easily obtained.

Further, even if the head having the current urethane core is made to have almost the same thickness, the weight is reduced by the absence of the core, so that the restriction on the design of the head having the core is released. Greater freedom of design. For example, if the total head is about 200 g, the urethane core is 30
~ 40g, the weight of the urethane core is
It becomes possible to distribute like. The head is enlarged as a whole without reducing the thickness of the outer shell. The sole plate is made heavier by changing the material, making it a low center of gravity head. The center of gravity is made lower and deeper by increasing the number of laminated layers of the sole and the side sole portion (back surface portion).
The moment of inertia is increased by increasing the number of laminated toe and heel parts.

In the above embodiment, only the carbon fiber prepreg is used, but glass fiber, boron fiber, etc. may be appropriately combined and used as required. Further, a face plate made of a metal such as titanium or titanium alloy may be separately provided on the face portion. The face plate may be attached to the head after molding with the above-mentioned mold, but may be attached to the face portion prior to being set in the mold and may be integrated with the outer shell during molding.

FIG. 3 shows a method according to another embodiment of the present invention. The difference from the above embodiment is that the air injection port 10b of the rubber bag for internal pressure 10 extends through the sole of the head. However, it is connected to the air supply unit 20 attached to the outer surface of the mold 40. On the heel side to which the shaft (not shown) is connected, the pin 21 is arranged in advance, and the prepreg 3 is laminated around the pin 21 in advance. After molding by heating / pressurizing, the pin 21 is removed to connect the shaft. Make sure to provide the holes. In the case of this embodiment, since holes are left in the molded head, it is necessary to close the holes with an appropriate material after taking them out of the mold.

[0026]

As described above, in the method for manufacturing a golf club head according to the present invention, a rubber bag is used instead of the conventional core portion, and this is covered with a prepreg of carbon fiber.
There is no need to prepare and prepare the core by a labor-intensive method as in the conventional case. Therefore, a golf club head having a hollow inside and no core is easily obtained.

Further, since the rubber bag covered with the carbon fiber is put in the forming mold and is molded by the mold while increasing the internal pressure of the rubber bag, the carbon fiber is applied to the inner wall of the mold by the internal pressure. Pressed to form a precise outer shell. In addition, since the rubber bag is deformable, for example, by stacking prepreg so that it is slightly larger than the final molded product,
It can be inserted by pushing it into the mold, which makes it possible to greatly reduce the dimensional accuracy of the laminated intermediate molded products.

Further, since the inside is hollow and the core is not provided, the weight is reduced, so that the volume of the head can be increased and the weight distribution can be devised so that the degree of freedom in design can be increased. A golf club that is easy to handle can be realized.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a step in a manufacturing method according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a golf club head manufactured by the method of the present invention.

FIG. 3 is a cross-sectional view showing a step in a manufacturing method according to another embodiment of the present invention.

[Explanation of symbols]

 1,10 Rubber bag for internal pressure 1a Inflated portion 1b, 10b Air inlet 2 Pipe 3 Carbon fiber prepreg 4,40 Molding die 20 Air supply 21 pin P Internal pressure

Claims (1)

[Claims] 1. A prepreg of carbon fiber is laminated on the outer peripheral surface of an internal pressure rubber bag inflated to approximate the internal shape of the head, the rubber bag is covered, and this is inserted and set in a molding die. After that, the mold is clamped, and the internal pressure of the rubber bag is increased to heat the mold with the mold to integrally cure the thermosetting resin therein, thereby producing a golf club head. Method.