JPS6122873A - Production of frame of molded tennis racket - 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 This application is a continuation-in-part of our U.S. patent application Ser. No. 604,864, filed April 27, 1984.

FIELD OF THE INVENTION This invention relates to tennis racquets, and more particularly to a method of forming a plastic tennis racquet frame.

Our U.S. Patent Application No. 604, filed April 27, 1984.
No. 864 describes a method for manufacturing a frame for a tennis racquet in which preformed grommets for use in stringing the racquet are cast into the frame.

The frame may be formed by wrapping graphite fibers around a preformed core member.

This structure f+il( is then placed in a mold,
Suitably cured to form a frame. Although the method of the present invention does not have the advantage of frame stringing made possible by our invention, it is possible to create a racket frame with greater strength by using a carbon-based plastic reinforced material such as graphite on the eave side. (1) provides a relatively simple and economical method for manufacturing a stringer in which the stringing channels are formed in the optimum required pattern during the formation of the 1/-mem. Pre-formed grommets cannot be used with the present invention; instead, in the present invention, the string receiving channel is provided with an optimum radius of curvature to minimize distortion to the strings. This avoids the disadvantage of most prior art racquets where the holes are drilled generally in a straight line through the frame and at a somewhat acute angle to the strings.

Objective σ) Improved results are achieved by the manufacturing method of the invention by forming frames from two identical +=e. Such halves may be formed by wrapping a plastic reinforcing filament, such as a thermoplastic, which may be graphite, around the top of a urethane foam preformed into the desired frame shape. A flat form of thermoplastic material in the shape of a frame and with openings formed according to the desired string channel pattern is sandwiched between the two halves, and these six elements are sewn together by graphite filaments or Mechanically join them together by suitable means such as driving with graphite bottles or vegs. The assembly thus formed is placed in a mold and heated to the appropriate temperature to harden the graphite material. After curing has taken place, the frame is again fitted with a suitable material for rendering the thermoplastic material into a spreadable state, so that the stringing channels remain formed in the frame and can be easily removed from said structure. heated to temperature.

Accordingly, it is an object of the present invention to provide an improved, relatively simple and economical method for frame manufacturing of shaped plastic tennis racquets.

Yet another object of the present invention is to provide an improved plastic molded tennis racquet frame in which a stringing channel or aperture is formed into the frame.

Other objects of the invention will become apparent as the following description is read in conjunction with the drawings.

1 and 2, a tennis racket frame 10 formed in accordance with the techniques of the present invention is shown. As can be seen, the frame has a urethane resin top 11 surrounded by graphite fibers 12. The frame has a "bost" stringing channel 14.
13, and when the string 15 is inserted between them, the sharp bending in the string is minimized.

As shown in Figure 6, a long member is made by wrapping a filament of a plastic reinforcing fiber material such as graphite around the upper part of the urethane, and two of the long members are formed into the shape of a flare L, and two identical Get half a frame.

4 and 5, the two halves of the frame IDA and 10B are then formed into the shape of the frame by a preformer and mechanically joined together to form a flat string channel. A molded member 20 is sandwiched therebetween. The molded member 2 is made of a thermoplastic material such as polyurethane and is molded into a frame shape. Molding member 2
0 has a plurality of apertures 2()A'Y formed therein, these apertures being formed with the required frame channel curvature. A frame channel is formed between the openings, as will become more apparent in the text below, and the two frame halves sandwiching the thermoplastic molded member therebetween.
The frame halves 10A and 10B are mechanically molded together by a graphite filament 21 stitched together. Other suitable means for mechanically joining these integral parts are graphite pins or pegs.

While these frame halves are joined together.

The resin impregnated in these half-wound filaments is still in a fluid state and can flow into the opening 2OA.

The assembly thus formed is placed in a mold and shaped to form a mating structure. When using a filament of graphite impregnated with epoxy resin, the mold is generally preheated to about 66°C (150'F) to effectively stabilize the graphite-containing material.
)σ) temperature for about 4 hours. Next, the hardened FJ
The structure is removed from the mold and allowed to cool to room temperature. Next, this part is formed by stretching the molding gl (20x) as shown in FIG. 6, so that the frame can be broken off. Heat to approximately 200'F.

Thus, the method of the present invention is useful for making plastic tennis strings from plastic materials, such as graphite-reinforced resins, in which the stringing channels are formed in the molding process without the need for grommets, grommet strips or spaghetti tubes.・It enables the manufacture of racket frames.

Furthermore, an optimal curvature for the stringing channel is provided that seeks to minimize the distortion imparted to the strings.

Although the present invention has been described and shown in detail, this is only intended as an illustration and should not be taken as a limitation, and the spirit and scope of the present invention is limited only by the claims in the heading. It is.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a tennis racket 7 manufactured according to the present invention, FIG. 2 is a partial cross-sectional view showing the internal structure 7 of the tennis racket of FIG. 1, nails, and FIG. Diagram showing the state of filament winding,
FIG. 4 is a plan view (not shown) of an assembled groove bottom element used in forming the frame of a tennis racket according to the method of the invention, and FIG. FIG. 6 is a diagram illustrating the process of mechanically mating together, and FIG. 6 is a diagram illustrating the disconnection of the string channel when carrying out the method of the present invention. 10... Tennis racket frame, OA. 10B...half part, 11...6 parts, 12...
・Graphai l [lii, 16...post,
14... String tensioning channel, 15... String, 2
0... Molded member, 2OA... Opening, 21.
...Graphite filament. (5 other people) Figure 5

Claims (1)

[Claims] 1. A method of manufacturing a frame for a tennis racket, comprising: forming first and second elongated core members; and surrounding each of said core members with a plastic reinforced filament for thermoplastic material. wrapped to completely surround said core member to form two identical elongated halves, having the shape of a racquet frame and corresponding in a plurality of shapes to the stringing channels of the desired racquet; forming a member in flat form from a thermoplastic material having a pattern of openings, forming the two halves in the shape of the frame, and sandwiching the two halves therebetween by thermoplastic joining means; the mechanically joined frame halves are placed in a mold, and the halves are formed together at a temperature suitable for curing the plastic. , allowing the cured plastic to cool to room temperature, heating the cured plastic to a temperature at which the flat-form member is expandable, and separating the flat-form member from the cured plastic frame. and leaving the required stringing channels in the frame member. 2. The method according to claim 1, wherein the filament is graite impregnated with an epoxy resin. 3. A method according to claim 1, characterized in that the frame halves are joined together by filaments stitched through the frame halves. 4. A method according to claim 1, characterized in that the frame halves are joined together by a pin driven through the frame halves. 5. The method according to claim 2, wherein the core member is urethane foam. 6. A method according to claim 2, characterized in that said flat forming member is polyethylene.