JPS61234882A - Production of racket frame and stick - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing racket frames for tennis, badminton, or squash, as well as stakes for gateball.

[Conventional technology]

Conventional tennis racket frames, for example, have been manufactured by processing wood, but the strength is not uniform, meaning that there are some areas where the strength is poor, and they are also poor in durability and relatively heavy. Recently, it has become necessary to widen the so-called sweet area and increase the frame area in order to improve the control roll of the pole. Racquet frames using fiber-reinforced plastic (FRP) are being manufactured in response to the need for racket frames to be tall and lightweight.

A racket frame using FRP is convenient for reducing weight and increasing size, and has a large degree of freedom in design. FRP lap racket frame A large number of so-called prepregs, which are semi-hardened reinforcing III impregnated with synthetic resin, are laminated around the outer periphery of a core material such as foam, and then heated and hardened in a mold.

[Problem to be solved]

In the conventional manufacturing method for FRPtJ racket frames, there are problems with the storage stability of the prepreg, as it hardens unless stored frozen, requires skill in laminating the prepreg, and also requires precise control of heating and pressure. There were drawbacks such as the resin flowing out or curing before pressurization, resulting in voids. In particular, voids on the surface of the molded product require repair in a post-process, which causes a decrease in productivity.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a racket frame or stake that solves the problem of pre-preg storage stability and improves workability and productivity.

Means for Solving Problems] In order to achieve the above-mentioned object, the present invention includes a step of coating the outer periphery of a core material with a layer of reinforcing fibers, and a step of placing the core material coated with the reinforcing fiber layer in a mold. The process consists of a setting step, and a step of closing the mold, injecting thermosetting resin through an injection port attached to the mold, and heating and curing it.

(Function) In this invention, since reinforcing fibers impregnated with synthetic resin are not used in a semi-cured state, that is, prepreg is not used, there is no problem regarding the storage stability of prepreg.
Even if you are not an expert, it becomes easy to use several machines, and work efficiency and productivity can be improved.

〔Example〕

Preferred embodiments of the present invention will be described below with reference to the drawings.

First, as shown in FIG.
Then, as shown in FIG. 2, the core material 1 covered with the reinforcing fiber layer 2 is set in a mold 3. Mold 3
is composed of an upper mold 31 and a lower mold 32, and the upper and lower molds 31 and 32 are configured to be openable and closable. The upper mold 31 and the lower mold 32 are closed, and a thermosetting resin is injected through the injection port 4 attached to the mold 3 and cured by heating. The core material 1 is a synthetic resin foam, for example, a material having a specific gravity of 0.04 to 0.
1 polyurethane foam, acrylic foam, or an elastomer tube is used. In addition, as the reinforcing fiber layer 2, glass, carbon, boron, Kevlar (aramid), silicon carbide, ceramic (alumina) can be used.
etc. are available. These fibers may be used alone or in combination, such as woven fabrics, knits, braids, non-woven cloths, and unidirectionally aligned fibers (UD). The reinforcing fiber layer 2 coated on the outer periphery of the core material 1 and set in the mold 3 is not yet impregnated with resin. As a means of covering the outer periphery of the core material 1 with the reinforcing m-thread layer 2, as shown in FIG.
Set it on a 6-piece braider (LI upper machine), cut foamed polyurethane (specific gravity 0.06), and create a core material 1 with a length of 1.51. The reinforcing layer [21 is rolled up at a speed of m/min. In addition, as another covering means, as shown in FIG.
wind up. That is, the core material 1 is made of a knitted material of reinforcing fibers 21.
Roll it around. As a further covering means, as shown in FIG. 5, a tube-shaped article may be prepared in advance with reinforcement 11M21, and the core material 1 may be inserted into this tube-shaped article.

In order to set the core material 1 coated with the reinforcing fiber layer 2 in the mold 3, the core material 1 is bent into a shape that follows the cavity of the mold 3, and if necessary, a frame formed by further bending is necessary. A reinforcing fiber layer 2 may be partially added at some locations. After setting the core material 1 coated with the fiber reinforcing layer 2 in the mold 3, the mold 3 is closed, and thermosetting resin is injected from the injection port 4 attached to the mold 3, so that the resin is injected into the mold. 3
The fiber reinforcement layer 2 is then hardened. In this step, the resin is effectively injected by removing air from the mold 3, and voids on the surface of the molded product can be prevented.

At this time, by applying internal pressure during the curing process of the resin, a resin layer with a uniform thickness and a molded product without voids on the surface can be obtained. As a method of applying internal pressure, a method of using a foaming core material for the core material 1, a method of expanding an elastomer tube with air, etc. can be adopted. As the thermosetting resin injected into the mold 3 through the injection port 4, unsaturated polyester resin, vinyl ester resin, epoxy resin, etc. are preferably used. When using an epoxy resin, it is preferable to use a liquid type and not to use a solvent in order to prevent void generation. Although epoxy resin is used in conventional FRP racket frames to improve strength and impact resistance, the solvent-diluted type is not suitable for use in the present invention.

Therefore, when an epoxy resin is used as the thermosetting resin in the present invention, a liquid epoxy resin that does not use a solvent or a hot-melt epoxy resin and a curing agent are used. As a curing agent, a polyamine type such as modified polyamine or polyamide resin for curing at room temperature is used.
For high temperature curing, acid anhydrides, imidazoles, boron trifluoride-amine complexes, dicyandiamide, etc. are used.

The epoxy resin and the curing agent are mixed before injection and are injected into the mold 3 under pressure using a plunger type pump or the like. As for the viscosity of the epoxy resin, the lower the viscosity of 100 voids or less, the better the impregnating property. Therefore, when using a high viscosity epoxy resin, a reactive diluent or the like may be added as necessary.

The curing time of the thermosetting resin varies depending on the curing agent used and the temperature of the mold 3, but if it is desired to shorten the molding cycle, molding may be performed at a high temperature.

In the illustrated embodiment, manufacturing of a racket frame has been described, but sticks for gateball and the like can also be manufactured in this manner.

〔effect〕

As explained above, according to the present invention, there are a step of applying a reinforcing fiber layer around the outer periphery of a core material, a step of setting the core material coated with the reinforcing fiber layer in a mold, and a step of setting the mold. Since the process consists of injecting thermosetting resin through an injection port attached to a closed mold and curing it by heating, there is no need to use prepreg as in the past, and there are no restrictions such as temperature during work and concentration when storing prepreg. Furthermore, unlike when a core material coated with prepreg is set in a mold, gelation of sticky resin or resin on the contact surface of the mold does not occur. According to this invention, when the core material covered with the reinforcing fiber layer is bent when being set in a mold, it does not wrinkle easily, and the fiber layer can also be added partially to areas that require correction during setting. . Unlike those using prepreg, even non-experts can set the mold with ease.

Overall, according to the present invention, workability and productivity are improved, and finishing accuracy is also excellent.

[Brief explanation of drawings]

Figure 1 is a perspective view showing the core material covered with a reinforcing Il fiber layer, Figure 2 is a perspective view showing the core material shown in Figure 1 set in a mold, and Figure 3 is the same as Figure 1. FIG. 4 is a perspective view showing another means for making the thing shown in FIG. 1, and FIG. 5 shows still another means for making the thing shown in FIG. 1. FIG. 1...Core material, 2...Reinforcement layer side L 3...Mold, 4...Injection port, 21...Reinforcement S Wisdom. Applicant Brideston Co., Ltd. Agent Patent Attorney Masu 1) Takeo No. 4

Claims (1)

[Claims] 1. A step of coating the outer periphery of the core material with a layer of reinforcing fibers, a step of setting the core material coated with the reinforcing fiber layer in a mold, and closing the mold and attaching it to the mold. A method for manufacturing a racket frame or stick, which comprises the steps of injecting a thermosetting resin through an injection port and curing it by heating.