JPH0326053B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of impregnating and strengthening the wood head of a golf club with a resin. The wood head of a golf club is made by cutting a wood material such as Persimmon into a predetermined shape so that the striking surface and the neck are parallel to the conduit of the wood, and is equipped with a striking surface insert. The face insert itself is made of a reinforced composite material, etc., and has excellent durability against impact forces, so if you always hit the ball against the face insert, there will be no problem. However, if a ball, especially a two-piece ball that has been frequently used in recent years, is repeatedly hit at a position where the face is off, the surface of the wood head will become dented by the hits. FIG. 6 shows the state of the dent 83 that occurs when repeated blows are applied to the toe 82 side of the face insert 81. In order to solve the above problem, the wood head is impregnated with a resin liquid consisting of one or more blends of thermopolymerizable plastic monomers, oligomers, or mixtures thereof, or unsaturated polyesters, and then heated or heated. Resin is polymerized and fixed by irradiation with gamma rays to improve impact resistance and durability. Furthermore, in order to improve impact resistance and durability, there are also so-called compression heads in which the wood head is impregnated with the above resin, which is then fitted into a mold similar in shape to the wood head and polymerized and fixed by heating and pressurizing it. It is appearing. However, in order to obtain sufficient impact resistance, it is necessary to impregnate a large amount of resin, and this increases the weight, making it impossible to produce a practical wooden head weighing less than 200 g. Due to the heat generated by the polymerization reaction of the resin, the center of the head becomes extremely hot, and this phenomenon becomes more pronounced as the resin impregnation rate increases, causing problems such as internal cracks and deterioration. The present invention focuses on the fact that the conduit 84 inside the wood of the wood head 8 is cut and finished in shape so that it runs parallel to the neck 85 and parallel to the striking side surface 80, as shown in FIG. The technical problem to be solved by the present invention is to minimize the increase in weight of the head due to resin impregnation, and to produce a head by devising the impregnation method and further devising the resin polymerization fixing method. In addition, the striking side surface should have impact resistance, and the entire head should have water resistance, dimensional stability, and paintability. In order to solve the above-mentioned technical problem, the method of the present invention provides a method of the present invention, which preferably has 4 to 18
A thickness of mm is impregnated with resin liquid at a high impregnation rate, then the entire body is impregnated with resin liquid at a low impregnation rate, and then a split mold with a hole similar in shape to the head and slightly smaller than the head is formed. The head is then heated while being pressurized to polymerize and fix the resin liquid. The wood head produced by the above method has good water resistance and paintability because the wood head is entirely impregnated with resin. In addition, due to the compression process during polymerization and fixation of the resin, the inside of the wood becomes densely packed, which is particularly noticeable in the face portion where a large amount of resin is impregnated, and it has sufficient durability against impact upon impact. Furthermore, most of the head, excluding the striking side, is impregnated with resin at a low impregnation rate, making it possible to keep the amount of impregnated resin to a small amount for the head as a whole, minimizing the increase in weight of the head due to resin impregnation. It is possible to minimize internal heat generation during polymerization and fixation of the resin by heating, and prevent cracking and deterioration. The present invention will be specifically explained below based on the drawings. FIG. 1 shows a resin impregnating apparatus used in the present invention, in which a vacuum pump 3 is connected to a sealed casing 1 with a lid 11, and a vent 13 is installed at an appropriate position on the wall of the casing 1 through a valve 12. It is provided. In the casing 1, trays 2 for placing the wooden heads 8 side by side are arranged in multiple stages, and each tray 2 is connected to a leveling device (not shown) such as a screw adjustable type, so that the wooden heads 8 can be placed as horizontally as possible. Supported. A perforated plate 22 is disposed horizontally within the tray 2 at a distance from the bottom 21 of the tray 2, and a metal plate 2 is also provided on the open surface of the tray 2 to prevent the wood head 8 from floating up.
3 is covered. The first and second 2 units are equipped with a stirrer near the housing 1.
Two resin tanks 4 and 5 are arranged, and each tank 4,
Resin liquid supply pipes 41 and 51 connected to the housing 1 are airtightly penetrated through the housing 1 via valves 42 and 52, respectively, and open above the uppermost saucer 2. In addition, each saucer 2, 2 has a discharge pipe 24, 24, 24.
, and each discharge pipe 24 communicates with both the first and second tanks 4,5 by a return pipe 27 provided with valves 25,26. Each saucer 2 is provided with a liquid level height adjusting tube 6, 6, which penetrates the bottom surface 21 of the saucer in a liquid-tight manner and can be moved up and down. A height adjustment device (not shown), such as a screw adjustment type, is connected to the adjustment tube 6. The adjustment pipe 6 of the lowermost saucer 2 is connected to the auxiliary tank 7 by a discharge pipe 75 penetrating the bottom surface of the housing 1. The auxiliary tank 7 has a transparent viewing window 71, and a return pipe 74 with valves 72, 73 allows the first,
It communicates with the second tanks 4 and 5. A method for impregnating a wood head with a resin using the above apparatus and a method for polymerizing and fixing the resin will be explained. First Step A first tank 4 contains a resin liquid (hereinafter referred to as first resin liquid) to be impregnated onto the striking surface side of the head, and a second tank 5 contains a resin liquid (hereinafter referred to as second resin liquid) to be impregnated into the entire head. Position the upper end of each control tube 6 from 4 to 18 points from the perforated plate 22.
Set it so that it is mm higher. The heads 8 are placed side by side on a perforated plate 22 with their striking surfaces facing downward, and a metal plate 23 is placed over the heads 8. The vacuum pump 3 is operated to reduce the pressure inside the housing 1. It is desirable to reduce the pressure to 50Torr or less. After being left in the above state for a certain period of time, the valve 42 is opened and the first resin liquid is injected into the uppermost saucer 2. When the injected resin liquid exceeds the height set by the regulating tube, it overflows the regulating tube 6 and flows into the lower tray. In this way, each saucer 2 is filled with the resin liquid to the set height from the upper stage to the lower stage as shown in FIG. When the resin liquid flows out into the auxiliary tank 7, the valve 42 is closed and injection of the resin liquid is stopped. Next, the valve 31 of the vacuum pump 3 is closed, and the valve 12 of the vent 13 is opened to return the inside of the casing to normal pressure. After a certain period of time in the above state, the valves 25, 73
It is opened and the resin liquid in each saucer 2 and auxiliary tank 7 is returned to the first tank 4. The first step is completed with the above operation, and at this point, the impact side surface of the wood head 8 has a resin-impregnated layer 8 with a high impregnation rate, in which the part that was immersed in the resin liquid is impregnated with the resin liquid.
7 is formed. 2nd step: Close the open valve of the device and close the lid 1 of the housing 1.
1 is opened, the height position of each adjustment tube 6 is adjusted to be slightly higher than the height of the head 8, the head 8 is covered with a metal plate 23 for preventing floating, and the lid 11 is closed. The valve 52 of the resin supply pipe 51 of the second tank 5 is opened and the valve 12 of the vent 13 of the housing 1 is closed.
Then, the valve 31 of the vacuum pump 3 is opened to operate the pump. Similarly to the above, the pressure inside the housing 1 is reduced, and each saucer 2 is filled with resin liquid up to the height of the upper end of the regulating tube 6. When the resin liquid flows out into the auxiliary tank 7, the valve 52 of the supply pipe 51 is closed to stop injection of the resin liquid. Further, the valve 31 of the vacuum pump 3 is closed, and the valve 12 of the vent 13 is opened to return the inside of the housing 1 to normal pressure. After leaving the above condition for a certain period of time, valve 2
6 and 72 are opened to collect the resin liquid into the second tank 5. This completes the second step, and the hitting surface of the wood head is impregnated with the first resin at a high impregnation rate in the first step, and the entire wood head is impregnated with the second resin at a low impregnation rate. There is. Third step: The wood head taken out from the housing 1 is placed in a mold and heated while being pressurized. The mold is of a three-part type having a mold hole similar in shape to the wood head, and the volume of the mold hole is preferably 88/100 to 97/100 of the volume of the wood head. Next, a specific example will be given of a persimmon head without a face insert or sole plate. Example 1 Mixing ratio of first resin liquid (parts by weight) Methyl methacrylate monomer 30 Styrene 40 Acrylonitrile 30 α・α′-azobisisobutyronitrile 1.2 Mixing ratio of second resin liquid (parts by weight) Methyl methacrylate 10 Trimethylolpropane trimethacrylate 90 α・α′-Azobisisobutyronitrile 1.3 Impregnation conditions Vacuum pressure reduction 30 Torr x 40 minutes 1st step Resin liquid level from the striking surface 4 to 18 mm Normal pressure immersion 50 minutes 2nd step Immersion 30 3rd step Pressure 55Kg/cm ² and temperature 90 in a three-part mold with a mold cavity volume of 88/100 of the volume of the wood head
Heat under pressure at ℃. When applying pressure, compress it gradually to avoid destroying the internal structure of the wood. Tests were conducted on resin-impregnated wood heads and wood heads manufactured by other methods under conditions based on the above data, and the results are shown in the table below. In Comparative Example 1, the level of the resin liquid was increased in the first step shown in Example to impregnate the entire head with the first resin at a high impregnation rate, and the second step was omitted and the third step of Example 2 was performed. thing. In Comparative Example 2, after performing the first and second steps shown in Examples, only polymerization and fixation by heating was performed without applying pressure in the third step. Comparative Example 3 was obtained by omitting the first step of the example and performing only the second and third steps. Comparative Example 4 is a plain wooden head that is not subjected to resin impregnation treatment.

[Table] In the table, impact resistance is the dent caused when a two-piece ball hits the same spot 500 times at a speed of 40 m/sec on the hitting side of the wood head. What is water absorption? Immersed in water at 50℃ for 24 hours. Water supply rate when water absorption rate = Weight after water absorption - Weight before water absorption / Weight before water absorption ×
100 Brinell hardness For the striking surface, compliant with JIS B-7724 As can be seen from the table above, in Comparative Example 1, the impact resistance, water absorption rate, and Brinell hardness were all the same as in the example, but the weight increased significantly, exceeding 200 g. This is not practical. In Comparative Example 2, the compression process was omitted, so the impact resistance was slightly inferior. In Comparative Example 3, since the face portion was not impregnated with the resin liquid at a high impregnation rate, the impact resistance was significantly inferior compared to the examples, and the Brinell hardness was also inferior. In Comparative Example 4, impact resistance, water resistance, and Brinell hardness were all significantly inferior to those of the Examples. Incidentally, the resin liquid used in carrying out the present invention is not limited to those mentioned above, and it goes without saying that resins for strengthening the wood head which have been used in the past may be used.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the device, Figure 2 is a slope view of the wooden head before resin impregnation, Figure 3 is a slope view of the wooden head arranged in a saucer, and Figure 4 shows the resin liquid applied to the striking surface side of the wooden head. FIG. 5 is an explanatory diagram of the process of impregnating the entire wood head with resin liquid, and FIG. 6 is a perspective view of the wood head with a recess formed in it. 8... Wood head, 87... Resin impregnated layer with high impregnation rate, 1... Housing, 2... Receiver, 6... Regulating tube.

Claims (1)

[Scope of Claims] 1. In the wood head manufacturing method in which the wood head is impregnated with resin to impart durability, the wood head is formed so that its striking surface is parallel to the conduit inside the wood, and then only the striking surface side is is soaked in a resin liquid and impregnated at a high impregnation rate to form a resin-impregnated layer with a high impregnation rate.Then, the entire head is impregnated with a resin liquid at a low impregnation rate, and then placed in a mold having a similar shape to the head. A method for manufacturing a wood head for a golf club, which comprises fitting the head and applying pressure while heating to polymerize and fix a resin liquid. 2. The method for manufacturing a wood head for a golf club according to claim 1, wherein the highly impregnated layer has an impregnation rate of 30% or more. 3. The method for manufacturing a wood head for a golf club according to claim 1 or 2, wherein the impregnation rate of the low impregnation portion is 3.0 to 8.0%. 4 The volume of the mold hole is 80/1 of the volume of the wood head.
Claims 1 to 3 which are 00 to 97/100
A method for manufacturing a wood head for a golf club according to any one of Items 1 to 1.