JPH06142232A - Forming method badminton racket frame - Google Patents

Abstract

PURPOSE:To provide a badminton racket frame of which work process in simplified and the deterioration of properties such as FRP due to thermal hysteresis is prevented by forming a joining material for connecting a shaft to a frame concurrently with the formation of the shaft. CONSTITUTION:A shaft compact 3A is formed out of a prepreg wound around a tube, and the end of the compact 3A is extended to form an extension section 3B. On the other hand, the center section of a joining member 5 comprising the core body 6 of rod type foamed body concealed with prepreg is covered with the extension section and connected to the compact 3A. Furthermore, both ends of the member 5 are inserted in both end openings of a frame 2 formed preliminarily out of a pipe at a joint with a shaft 3. Then, a product so made is laid in a molding die, and the compressed air or the like is supplied from a grip end section for inflating the tube. Heat and pressure are, then, applied to cause the secondary foaming of the core body 6 of the member 5, thereby forming a badminton racket frame.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding a racket frame for badminton (hereinafter abbreviated as a racket frame), and more specifically, a connecting member connecting a frame and a shaft to a grip are integrally formed. The present invention relates to a molding method.

[0002]

2. Description of the Related Art As a conventional racket frame forming method, a stretchable tube having a length corresponding to a frame and a shaft is coated with a prepreg which has been preliminarily impregnated with resin into a semi-cured state. Put in a molding die, pressurize air into this tube, press the coated prepreg to the molding die and heat-mold it, and form the frame and shaft integrally, or preform the frame and shaft separately. It is known that the racket frame is formed by connecting the two with a substantially T-shaped connecting member.

At present, a structure in which a connecting member is used to connect the frame and the shaft is generally used. To mold such a racket frame, as shown in FIG. 4, the frame 12 and the shaft are previously prepared. 13 is formed of FRP (fiber reinforced plastic) or aluminum into a pipe shape, and the horizontal support portion 15a of the substantially T-shaped coupling member 15 formed of metal or the like is inserted into the openings 12a and 12a at both ends of the frame, and the shaft end portion is formed. The vertical support portion 15b of the coupling member is
Are inserted and connected. Also, the outside is covered with a reinforcing material 20 such as FRP and cured to reinforce the connecting portion.

[0004]

In the conventional racket frame, the connecting member 15 is provided inside the pipes of the frame 12 and the shaft 13, and the FRP reinforcing member 2 is provided outside the connecting member 15.
The purpose is to cover 0,
It was possible to improve the mechanical durability of the connecting portion and narrow the wind pressure area to some extent. However, it takes time and effort to form each member in advance and to connect each member with a binder.

Further, since a metal material having mechanical strength is used for the connecting member, the weight is not sufficiently reduced, and
When the shaft is made of FRP or the like, the difference in mechanical strength and bending between the shaft and the coupling member has also been a cause of failure to follow the bending of each of the frame and the shaft. In addition, the shaft is made of FRP, etc., the reinforcing material of the connected FRP is covered with the joining member, and it is placed again in the molding die to be heated and pressed to be hardened. There was a risk that the physical properties would be deteriorated and the material would be changed due to the heat history, which could affect the rigidity. Therefore, in view of the above-mentioned conventional drawbacks, the present invention is a method for forming a racket frame including a shaft and a frame made of FRP, and at the time of forming the shaft, simultaneously forms a connecting member for connecting the shaft and the frame. Therefore, it is intended to provide a method for forming a racket frame by more firmly connecting the frame and the shaft.

[0006]

In order to achieve the above object, the present invention has the following molding method. That is, in the method of forming a racket frame including a frame, a shaft, and a grip, a stretchable tube is wrapped with a prepreg which is a semi-cured state obtained by previously impregnating fibers with resin,
Bonding formed by forming a shaft molded body having a length corresponding to the length of the shaft and the grip, and extending the tip to provide an extension portion, while covering the rod-shaped foam core body with a prepreg. The member covers the central portion of the coupling member with the extension portion and is connected to the tip of the shaft molded body, and both ends of the coupling member are connected to the shaft of the frame in which the both ends of the coupling member are formed in the ball striking face shape in advance. Insert it into the inside of the opening on both ends to make a racket frame shape, place it in the mold, close the mold, inject compressed air etc. from the grip end to expand the tube, This is a method for molding a racket frame for badminton, characterized in that the prepreg is pressure-bonded to a molding die and is heated and pressed to secondary-foam the core body of the coupling member.

[0007]

As described above, according to the method of the present invention, the shaft and the connecting member for connecting the shaft and the frame are integrally formed, and at the same time, the frame and the shaft are connected to form the racket frame. Therefore, the racket frame can be formed by molding once, and the working process is simplified. Further, according to the method of the present invention, since the core body of the joining member is formed while being secondarily foamed when heated and pressurized, an internal pressure is applied to the FRP binding material itself, and the bonding and adhesion with the frame is further strengthened. In addition, the connecting portion can be formed smoothly. Further, unlike the conventional case, it is not necessary to heat and press-mold again by using a coupling member in order to connect the hardened and molded shaft to the frame.
Physical properties of members such as RP deteriorate due to heat history,
There is no fear that the material will change. Further, since the binding material and the shaft are formed of the same material, the elastic modulus from the shaft to the frame is continuous, so that the flexibility of the racket frame bending and the flex design is improved.

[0008]

EXAMPLES The present invention will be described below based on examples.
1 and 2, FIG. 1 shows a racket frame 1 formed by the method of the present invention, which comprises a frame 2, a shaft 3, a grip 4, and a connecting member 5 connecting the frame and the shaft. There is. The frame 2 is formed of a pipe made of a material such as aluminum,
Openings 2a, 2a are provided at both ends connected to the shaft. Shaft 3 is made of FR such as carbon fiber
The connecting member 5 is formed of P, and the connecting member 5 is connected to the distal end of the connecting member 5 by the FRP extension 3B for shaft molding.

The connecting member 5 is provided on the outer side of the foam core body 6,
The FRP bonding material 5a similar to the shaft molding material is laminated and formed. The core body 6 of the connecting member 5 is preferably a material that is secondary foamed by heating, such as EVA, thermoplastic polyester resin foam, and styrene foam.
The FRP binding material 5a that coats the core body 6 may be a sleeve-shaped prepreg or a woven cloth prepreg, and both end portions 5b and 5b of the coupling member 5 have a core body formed by secondary foaming. It is preferably in a state of being closed by the FRP binding material 5a so as not to bulge from the portion.

To form the racket frame 1 described above, first, an aluminum pipe is bent into a frame shape and a gut insertion hole is opened. On the other hand, a stretchable tube 7 is coated with a prepreg of carbon fiber to form a shaft molded body 3A corresponding to the length of a shaft and a grip.
To form. At this time, in order to connect the joint member molded body 5A later, the tip portion of the prepreg in the outer layer of the shaft molded body 3A is extended to form the extension portion 3B. Then, a rod-shaped core body 6 is formed of foam, and sleeve-like prepregs having one end closed are covered from both ends to form a coupling member molded body 5A. Next, the coupling member molded body 5A is placed at the tip of the shaft molded body 3A, and the shaft molded body 3
The connecting member molded body 5A is covered with an extension portion 3B formed of a prepreg extended to the front end portion of A so as to connect the two.

Then, the openings 2a, 2a at both ends of the frame are formed.
Adhesive is applied to the both ends 5b, 5
b is inserted and placed in the mold, the mold is closed, compressed air or the like is injected from the tube end 7a of the grip end to expand the tube 7, and the prepreg is crimped into the mold. The racket frame 1 integrally molded by heating and pressurizing at 150 ° C. and a pressure of 5 to 10 kg for 20 to 25 minutes.
Was molded. FRP binding material 5a forming the binding member 5
In the case of, the sleeve-like prepreg with one end closed was covered from both ends, but when covering the sheet-like prepreg, both ends 5b, 5b may be bound. If the core body 6 is securely surrounded by the prepreg, the FRP bonding material 5a is pressure-bonded to the inside of the molding die or the frame when the core body 6 of the coupling member is secondarily foamed during the heat molding, so that the connection is ensured.

[0012]

As described above, according to the method of the present invention,
Since it is a method of molding the racket frame integrally with the frame by the connecting member when molding the shaft and the grip, the process can be simplified and there is no repeated heating and pressing unlike the conventional method. The racket frame is further improved in durability without causing physical deterioration or material change due to heat history in the frame or the shaft. Further, the connecting member does not use a material different from the material forming the shaft as in the past, but uses the same material,
Since the heat curing molding is performed at the same time, the elastic modulus is not divided between the two, and the racket frame has continuous flexibility.

[Brief description of drawings]

FIG. 1 is an external front view of a racket frame formed by the method of the present invention.

FIG. 2 is an enlarged cross-sectional explanatory view of a portion A of FIG.

FIG. 3 is a schematic explanatory view of a molding method according to an embodiment of the present invention.

FIG. 4 is an explanatory cross-sectional view of a connecting portion between a frame and a shaft of a conventional racket frame.

[Explanation of symbols]

 1 Racket Frame 2 Frame 2a Opening 3 Shaft 3A Shaft Form 3B Extension 4 Grip 5 Coupling Member 5A Coupling Member Forming 5a FRP Coupling 5b End 6 Core 7 Tube 7a Tube End 12 Frame 12a Opening 13 Shaft 15 Coupling member 15a Horizontal support 15b Vertical support 20 Reinforcement material

Claims (1)

[Claims] 1. A method for forming a racket frame for badminton comprising a frame, a shaft and a grip, wherein a stretchable tube is wrapped with a prepreg which is preliminarily impregnated with resin into a semi-cured state, and the length of the shaft and the grip is increased. While forming a shaft molded body having a length corresponding to the above, and extending the tip to provide an extension portion, a connecting member formed by coating a rod-shaped foam core body with a prepreg is used as the extension portion. The central part of the connecting member is covered with and is connected to the tip of the shaft molded body, and both ends of the connecting member are provided on both ends of the frame, which is formed in the ball striking face shape by pipes, at the connecting part with the shaft. Insert it inside the racket frame shape, place it in the mold, close the mold, and inject compressed air etc. from the grip end tube Is expanded, the molding prepreg is pressure-bonded to a molding die, and the molding is performed while heating and pressurizing the core body of the coupling member while secondary-foaming the badminton racket frame.