Composite racquet with double tube head frame
a technology of double tube and composite racquet, which is applied in the field of composite racquet with double tube head frame, can solve the problems of many limitations of materials, significant weight limitations of aluminum extrusions, and differences in engineering problems associated with them, and achieves superior strength, stiffness and weight properties, and increases the effective strung area of the racquet.
Inactive Publication Date: 2006-10-05
EF COMPOSITE TECH
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Benefits of technology
The double-tube frame structure provides superior strength, stiffness, and weight properties compared to single-tube composite and aluminum frames, with increased unimpeded string area and improved projectile-returning power.
Problems solved by technology
While each succession of materials in general improved strength to weight ratios, the engineering problems associated with them differ markedly.
While forming racquet frames from extruded aluminum alloys is relatively cheap because of lower labor costs, the material has many limitations.
Aluminum extrusions have substantial weight limitations.
While there have been multiple-tube composite structures, it has been found that any internal divisions, bridges or lumens placed in these tubes are difficult to control in their placement because of variations in bladder air pressure, and attempts to include them in the past have been found to cause significant quality control and production problems.
Method used
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[0070] To demonstrate the technical advantages of the structure of the present invention over prior art and other structures, a series of tests was performed on a racquet according to the invention and having the morphology shown in FIGS. 1-4, and also on other racquet structures. FIGS. 8, 9 and 10A-10D are representative cross-sectional views of these other tested structures.
[0071]FIG. 8 is a cross-sectional view of a prior art composite racquetball racquet frame. This cross section is basically an oval 200 with an indentation on one side. “Traditional oval” racquet 202 was constructed of composite materials similar to those used in the present invention and substantially the same as those in the sample according to the invention that was tested herein.
[0072]FIG. 9 is a cross-sectional view of a prior art aluminum racquetball racquet frame 204. “Aluminum traditional oval” frame 204 has a pair of internal supports 206, 208 for purposes of stiffening. The control of the placement o...
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Abstract
A sports racquet frame is built of a composite of laminations of fibrous material as impregnated by a thermosetting resin. The head section of the frame has an upper tube preferably disposed above the string bed plane and a lower tube preferably disposed below the string bed plane. A solid bridge of material integrally joins the upper tube to the lower tube. In a preferred embodiment the bridge is disposed radially exteriorly of the center line of the tubes, to maximize the length of string segments, which are strung to the bridge.
Description
RELATED APPLICATIONS [0001] This application is a divisional of copending U.S. patent application Ser. No. 10 / 854,938 filed May 27, 2004 and assigned to the assignee hereof. The specification and drawings of that application are fully incorporated by reference herein. BACKGROUND OF THE INVENTION [0002] Sports racquets, which term includes tennis rackets, squash racquets, badminton racquets and racquetball racquets, are all strung with strings across a head portion of a frame, which head portion surrounds and defines a string bed. The string bed is designed to intercept and return a game piece such as a shuttlecock, racquetball or tennis ball. [0003] Up into the 1960's sports racquets were made of wood. These racquets were replaced with racquets made of metal, typically of aluminum alloy, although steel has also been used. In the 1970's thermoplastic injection molded racquets were attempted, as reinforced with fiber whiskers. Also in the 1970's sports racquets began to be made from a...
Claims
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IPC IPC(8): A63B51/00A63B49/02A63B49/10
CPCA63B49/007A63B2209/02A63B49/106A63B49/02A63B49/11A63B49/028A63B49/022A63B49/10
InventorFILIPPINI, RAFAEL G.
OwnerEF COMPOSITE TECH