JPS6046988B2 - Racket frame manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a racket frame in which a fiber-reinforced thermosetting resin is molded into the racket frame.

Composite racquet frames generally include a shell consisting of multiple layers of woven glass or carbon fiber impregnated with a thermosetting resin and a foam core intimately bonded to the shell. .

The manufacture of such composite structures typically requires internal pressure to force the shell into intimate contact with the interior surface of the feed cavity and to assume the shape of the shell. There are two methods for generating sufficient internal pressure: direct (blow molding) and indirect (foam molding). In the first method, the sides of the shell are pressed tightly against the inner wall of the feed cavity by means of compressed air. A foamable thermosetting component is then supplied to the hollow central portion, which is then foamed by heating and hardened within the inner wall. This additional manufacturing step results in additional manufacturing costs. In the second method, multiple layers of resin-impregnated woven fibers are wrapped around a foamable core component and then placed into a casting cavity and molded.

When heating is applied, the blowing agent acts on the core component to create pressure to create the desired cast shape after curing.
Although the latter method is simpler than the former method, the temperatures for gelling and curing the resin-impregnated fibers and for foaming the thermoset plastic resin are not equal, hence the occurrence The applied pressure is not controllable and the resin from the core penetrates into the shell layer, thereby destroying the fiber reinforcement as well as the fiber orientation. In accordance with the present invention, a method for manufacturing a racket frame includes an elongated cast cavity having a length extending from a handle portion, around a head portion, and back to the handle portion. providing a flexible strip member containing a thermosetting resin component and reinforcing fibers into the casting cavity; bringing the two flexible strip members together to form a structural member; The steps are: bending the structural member in the tool into the shape of a racket frame; curing at a temperature; and removing the strip after curing.

The racket frame thus formed can have an I-shaped cross section, or a concave lens shape, and can also have a notch-like section.

The fibers used here can be carbon fibers, glass fibers, boron fibers, Kev!Ar or other reinforcing materials. Strip members can be removed from the molded frame by grinding or by using a mold release agent.

It is an object of the present invention to provide a method that can be used to produce a solid fiber-reinforced racquet frame without applying internal pressure during molding to form a mold.

These and other objects, features and advantages of the invention will become more apparent from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings.

As shown in FIGS. 1 and 2, a racket frame 10 according to the present invention is made of a thermoset resin reinforced with fibers such as carbon fibers, glass fibers, boron fibers, Kevlar, etc. It is made by casting.

The mold used in this invention is a flexible strip member 11 of such length as to extend from the handle portion, around the head portion, and then back to the handle portion. Each of these strip members 11 has a casting cavity 13 over its entire length, and the two casting cavities, after being butted together, have an I-type (FIG. 2e), a concave lens-type ( (Fig. 3), a rectangle with a groove on one side (Fig. 4), and a rectangle with a groove on one side and a radius on the other side (Fig. 5). I can do it. These strip members 11 are used instead of rigid molds which are more expensive to manufacture. These parts are made of plastic, wood valves, bamboo wood, etc. The plastic strip member can be made by extrusion or injection molding, while
The shaped cavity can be obtained by cutting wood or bamboo. During the process, the strip member 11 is filled with thermosetting resin and fibers 14, and then the two strips 11
are pressed together and bent into the shape of a racket frame,
It is then placed into a tool for shaping. In Figure 3, 2
With the two strip members 21, a racket frame 22 having a concave lens-shaped cross section is obtained. As shown in FIG. 4, the two strips 31 and 41 make it possible to obtain a frame with a combined rectangular 42 and U-shaped 32 cross section. In FIG. 5, one strip member 51 has a U-shaped groove 52 and the other strip member 61
has a curved groove 62. The groove 62 is first provided with a layer of fiber-reinforced resin 63 and then filled with a layer of wood 64. The two strip members 51 and 61 are bent together into the shape of a racket frame.

The resin is then cured at a certain temperature.

After curing, both strip members can be removed using a mold release agent or by grinding. Although the invention has been described above, it will be apparent that various modifications and changes can be made without departing from the scope of the invention.

The invention, therefore, is limited only as indicated in the appended claims.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a racket frame according to the present invention. Figure 2a is a perspective view of a flexible strip member according to the invention. Figure 2b is a perspective view of the strip member filled with casting compound. FIG. 2c is a cross-sectional view of two pressed strip members. FIG. 2e is a sectional view of a racket frame according to a first embodiment of the present invention.
FIG. 3 is a sectional view of a racket according to a second embodiment of the present invention. FIG. 4 is a sectional view of a racket frame in a third embodiment of the present invention. FIG. 5 is a sectional view of a racket frame in a fourth embodiment of the present invention. Code explanation, 1
0, 22... Racket frame, 11, 21, 31
, 41, 51, 61... Strip member, 13...
... Casting cavity, 14 ... Resin and fiber,
63...Fiber-reinforced resin.

Claims (1)

Claims: 1. A flexible strip member having a length extending from the handle portion, around the head portion, and then back to the handle portion, and having an elongated casting cavity extending through the length. preparing, injecting a thermosetting resin component and reinforcing fibers into the casting cavity, bringing together two flexible strip members to form a structural member, and rolling the strips together in a fixture. A method for manufacturing a racket frame comprising the steps of bending the racket frame into the shape of the racket frame, curing it at a certain temperature, and removing the strip member after curing. 2. The method of manufacturing a racket frame according to claim 1, wherein the structural member has an I-shaped cross section. 3. The method of manufacturing a racket frame according to claim 1, wherein the structural member has a concave lens-shaped cross section. 4. The method for manufacturing a racket frame according to claim 1, wherein the structural member has a notch-shaped section. 5. The method for manufacturing a racket frame according to claim 1, wherein the fibers are selected from the group consisting of carbon fibers, glass fibers, boron fibers, and Kevlar. 6. The method for manufacturing a racket frame according to claim 1, wherein the strip member is removed by grinding. 7. The method for manufacturing a racket frame according to claim 1, wherein the strip member is removed using a mold separating agent.