Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS3647211 A
Publication typeGrant
Publication dateMar 7, 1972
Filing dateJun 8, 1970
Priority dateJun 8, 1970
Publication numberUS 3647211 A, US 3647211A, US-A-3647211, US3647211 A, US3647211A
InventorsJames H Doessel, Patrick A Mckenne
Original AssigneeJames H Doessel, Patrick A Mckenne
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Plastic tennis racket having predetermined cross sections effecting flexibility
US 3647211 A
Abstract
A tennis racket frame of molded plastic includes head, shaft and handle portions with the cross sections thereof, together with the characteristics of the plastic material, providing maximum flex at the upper end of the head, secondary flexing at the throat area adjacent the head, lesser flexing at the base of the head, and the minimum of flexing at the shaft adjacent to handle. Shaft apertures and texturing of the handle can be molded in at the same time that the proper cross-sectional areas of these parts are formed. The cross-sectional area of the head is T-shaped and the string apertures are bridged by guides about which the strings extend in order to reduce wear thereof.
Images(2)
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

i 0 United States Patent [151 3,647,21 1

Doessel et a1. Mar. 7, 1972 [54] PLASTIC TENNIS RACKET HA/VING 228,650 2/ 1925 Great Britain.. ..273/73 H PREDETERMINED CROSS SECTlONS 381,673 10/1932 Great Britain... ..273/73 H 450,521 10/1934 Great Britain.... ..273/73 F EFFECTING FLEXIBILITY 815,921 7/1959 Great Britain ..273/73 C [72] Inventors: James H. Doessel, 7429 N. Claremont 1,048,807 1/1959 Germany ..273/73 R Ave., Chicago, 111. 60645; Patrick A. 1,816,112 10/1969 Germany... ..273/73 F McKenna, 708 Long Road, Glenview, 111. 1,923,910 11/1969 Germany... ..273/73 C 60025 237,395 7/1925 Great Britain .....273/73 D Filed Junes 1970 1,512,401 1/1968 France ..273/73 R [21] A l, N 44,109 Primary ExaminerAnton 0.0echs1e Assistant Examiner-Richard J. Apley 52 US. Cl. ..273/73 c, 273/73 D, 273mm. 1 Mama-v [51] Int. Cl. ..A63b 49/10 7 ABSTRA T [58] Field of Search ..273/73, D16. 1, 80, DIG. 7 [5 1 C A tennis racket frame of molded plastic includes head, shaft [56] References Cit d and handle portions with the cross sections thereof, together with the characteristics of the plastic material, providing max- NIT STATES PATENTS imum flex at the upper end of the head, secondary flexing at the throat area adjacent the head, lesser flexing at the base of gigs the head, and the minimum of flexing at the shaft adjacent to 234l053 M1944 Maser; [80 B x handle. Shaft apertures and texturing of the handle can be 2878O20 3/1959 g; 273/73 F molded in at the same time that the proper cross-sectional l 7 1 H1936 Spencer D areas of these parts are formed. The cross-sectional area of the head is T-shaped and the string apertures are bridged by 2,940,492 6/1960 Curry et a1 ..273/73 F UX guides about which the wings extend in order to reduce wear FOREIGN PATENTS OR APPLICATIONS thereof- 227,012 1/1925 Great Britain ..273/73 D 5 Claims, 7 Drawing Figures v PATENTEDMAR 11912 SHEET 1 0F 2 ,7 ON mm w.

INVENTORS JAMES H. DOESSEL PATRICK A. M KENNA NQE PATENTEDNAR (I972 3.647.211

SHEEIZ or 2 FIG.3

INVENTORS JAMES H. DOE EL PATRICK A. M ENNA PLASTIC TENNIS RACKET HAVING PREDETERMINED CROSS SECTIONS EFFECTING FLEXIBILITY GENERAL Tennis racket frames are normally made of wood or metal which can provide many of the necessary physical properties for satisfactory performance. However, during use there are generally problems of racket distortion with the passage of time, for example warping of a wooden racket, or distortion with actual use, for example bending of a metal frame. In providing a racket with proper playing characteristics of balance and feel," as well as desirable durability, the cost of manufacture increases considerably.

SUMMARY An object hereof is to reduce the cost of racket manufacture by forming the frame of a molded plastic.

Another object is to form a tennis racket frame which has minimum distortion over a period of time and which has minimum response to temperature and humidity changes.

Another object is to provide a plastic tennis racket which has the flexibility, strength, and weight to exhibit highly desirable playing feel and balance.

In a specific form the tennis racket hereof includes a frame which is preferably formed of a molded plastic such as polycarbonate resin with up to 20 percent glass content. The shaft and throat areas are apertured, and the cross section of the loop which forms the head is made generally T-shaped. These cross sections are related to the bending characteristics of the plastic such that the upper portion of the head has the greatest flexing characteristic, the throat area has the next greatest flexing characteristic, and the base of the head has a still lesser flexing characteristic. The shaft adjacent the handle has a still lesser flexing characteristic and of course the handle has the least flexing. In order to reduce string wear the T- shaped cross section of the head has string apertures which are bridged by raised portions or guides about which the strings pass through smoothed and rounded troughlike areas in order to increase the string life of the racket. The handle can have either a molded texture or can be separately wrapped depending on the grip desired.

THE DRAWINGS In the drawing, FIG. 1 is a plan view of a tennis racket constructed in accordance with the invention;

FIG. 2 is a side view of the racket of FIG. 1 with the sections taken as shown in FIG. 1;

FIG. 3 is an end view of the racket of FIG. 1;

FIG. 4 is a greatly enlarged view of the string hole construction of the racket of FIG. 1;

FIG. 5 is a sectional view along the lines 5--5 of FIG. 4;

FIG. 6 is a modified form of the string hole construction of FIG. 4; and

FIG. 7 is a still further modified form of the string hole construction of FIG. 4.

DETAILED DESCRIPTION The molded tennis racket of FIGS. 1-5 is preferably formed in one piece. The racket 10 includes (FIG. 2) a handle section A, a shaft section B, a throat section C, a lower head section D, and an upper head section B. The handle section A is hollow with an aperture 12 extending therein almost the full length of the handle. As shown in FIG. 1 the exterior of the handle is roughened or knurled at 14 providing a gripping surface.

The shaft section B, as well as the throat section C, include apertures 16 which help to provide the desired amount of flexing, discussed in detail subsequently, and also play a part in fixing the total weight of the racket which should be of the order of l2 or 13 ounces and similar to the weight of prior art wooden rackets. The apertures further help to establish the racket balance, that is the center of gravity.

The head of the racket 10 is in the shape of an oval as viewed from the plan view of the racket in FIG. 1 and has a periphery with a cross section in a generally T shape as visible in FIG. 2. The base of the T-shape 18 faces inwardly and the top of the T-shape 20 forms the outer periphery of the head. As seen in FIG. 1 the base of the T-shape 18 is apertured so that the strings can be passed through the apertures and strung across the racket in the usual woven pattern. Details of the stringing construction are discussed below.

The racket 10 is preferably molded in one step and composed of a plastic material which has the necessary mechanical properties. Consideration must be given to the impact strength of the material, since considerable force can be generated in the racket during use and to the fatigue characteristics of the material which may permit failure with age and use. Furthermore, there must be a proper degree of flexibility in order to have the proper feel and to avoid likelihood of breaking through brittleness. It should also be recognized that the head of the racket is under a considerable stress due to the tension of the strings 24 so that the material of the racket must have a minimum tendency to creep or distort under this stress with time. After repeated stressing and consequent racket deflection or bending through striking of the ball, the plastic material must have a memory quality such that it returns to its original undistorted shape. Plastic material will nonnally have virtually no moisture response, compared to wood, e.g., but it should be selected to avoid brittleness with low temperatures and distortion with heat normally encountered.

In addition to the above-described strength and aging properties it is, of course, also necessary that the material not be unduly dense so that the weight of the racket would go beyond that normally found in wooden rackets, which may be, for example, 12% ounces.

One suitable material for the composition of the racket is a polycarbonate resin which has been combined with approximately l0-20 percent glass fiber. One such plastic material is available, for example, under the trade name Lexan. Other suitable materials are acrylonitrile-styrene with 20 percent glass or acrylonitrile-butadiene-styrene with 20 percent glass.

We have also found that in constructing the racket 10 the various lettered portions thereof of FIG. 2 should have a certain relationship of flexing characteristics as the racket is viewed in FIG. 2, that is flexing in a direction transverse to the view of FIG. 1. This relationship is such that the upper head portion E has the greatest flexing characteristic, the throat portion C has the next greatest flexing characteristic, and the lower portion of the head D has a lesser flexing characteristic. The shaft B has a still lesser flexing characteristic, and the handle A has the least amount of flexing. These references to flexing characteristic all refer to bending of the racket as viewed in FIG. 2 with the handle section A clamped and the force applied to the outer end of the head. The relationship of comparative flexing is achieved by adjusting the cross sections of the various portions in relation to the bending characteristics of the material of the racket. For example, as seen in FIG. 2 there is a tapering of the head as it extends outwardly from the throat area C which promotes an increased bending characteristic in the upper head portion E. The throat portion C is tapered somewhat toward the shaft portion B as seen in FIG. 2 and further has the apertures 16 through the flat plan of the racket which can be adjusted in size to achieve the desired bending characteristic. Similarly, the apertures in the shaft section B can control the flexing characteristic of that portion to be less than that of the lower head portion D. It will also be recognized that the apertures 16 provide some advantage of reduced windage effect as the racket is swung in use.

Since the racket strings 24 are under a tension of 50 to 65 lbs., and since this tension increases considerably beyond that when a tennis ball is struck, wear can develop at the points where the strings contact the head of the racket. As shown in FIGS. 4 and 5 we contemplate the addition of raised rounded string guides or bunkers 28 to avoid having the string 24 pass around sharp corners.

The base of the T-shape 18 of the head has apertures 30 therein which are in pairs at opposite sides of the raised annular half-ring 28. As seen in FIG. 4 the strings extend from one side of the oval head to the other and pass under the T-shaped base or flange 18 and up through a hole 30. The string then passes around the circular periphery of the raised portion or guide 28 and down through the adjacent hole.

Modified forms of the string guide are shown in FIGS. 6 and 7. In the form of FIG. 6 the string 24 passes around the circular raised guide 28a which is molded integral with flange 18 of the racket head.

In the form shown of FIG. 7 the string 24 passes around a series of raised projections or posts 281) which are spaced in a circular pattern approximately corresponding to the periphery of the circular guide 28a of FIG. 6. It should be clear that other configurations beyond the half-ring guide 28 of FIG. 4, the circular guide 280, and the series of posts 28b are possible to accomplish the smooth reversal of the string without creating focal points for strain.

The described tennis racket, formed of plastic, has the advantage of reduced influence by environmental conditions, for example as compared to the influence of humidity on a wooden racket. It also has the advantage of ruggedness and reduced cost, while at the same time maintaining a weight and playing feel much like other known rackets. The described flexing characteristics and the means of achieving them, as well as the means of anchoring the string in the racket head, contribute to an overall design which is both economical for manufacture in production quantities and highly durable and serviceable in use.

We claim:

1. A tennis racket frame for stringing including a closed loop head portion having a T-shaped cross section, with the base of the T projecting inwardly substantially parallel to the head plane and forming the string support structure, said racket frame further having a handle portion joined to said head portion at a throat portion by a shaft portion, all of said portions of said frame being an entirely one-piece molded plastic material reinforced with glass filler, each of said portions of said frame having a predetermined cross section, said shaft and throat portions having openings therethrough to coact with said predetermined cross sections to control and determine the flexing of said racket frame, and wherein the cross section of the upper portion of said head portion with respect to the cross section of said throat portion providing a greater degree of flexing transverse to the plane of said upper head portion than the degree of flexing of said throat portion, the cross section of said throat portion with respect to the cross section of said head portion adjacent said throat portion providing a greater degree of flexing of said throat portion than the degree of flexing of said head portion adjacent said throat portion, the cross section of said head portion adjacent said throat portion with respect to the cross section of said shaft portion providing a greater degree of flexing of said head portion adjacent said throat portion than the flexing of said shaft portion and the cross section of said handle portion having the least degree of flexing than any other portion of said racket frame.

2. The combination of claim 1 in which said plastic material is polycarbonate resin reinforced with 10 to 20 percent glass filler.

3. The combination of claim 1 in which the base of said T- shaped cross section of said head portion includes apertures for strings of said racket, pairs of adjacent ones of said string apertures having raised guides therebetween to receive a racket string from one side of said head portion through one of said apertures, around one of said guides and through the other of the pair of said apertures.

4. The combination of claim 3 in which said guides have circular peripheries about which the racket string may pass.

5. The combination of claim 1 in which the surface of said handle is textured to facilitate manual gripping thereof.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1548134 *Jan 31, 1923Aug 4, 1925Gallaudet Edson FTennis racket and the like
US2059917 *Jul 3, 1935Nov 3, 1936Vernon SpencerTennis racket
US2066962 *Apr 16, 1934Jan 5, 1937Lloyd CrossShaft for golf clubs or the like
US2341053 *Apr 24, 1941Feb 8, 1944Robert B RansomFlexure member
US2878020 *Dec 16, 1949Mar 17, 1959Robinson Roy HRacket for batting games
US2940492 *Jul 22, 1955Jun 14, 1960Fayette R Plumb IncFiber-glass reinforced percussive tool handle
DE1048807B * Title not available
DE1816112A1 *Dec 20, 1968Oct 16, 1969Carlton Tyre Saving Co LtdSchlaeger und Schlaegerrahmen
DE1923910A1 *May 10, 1969Nov 20, 1969Zeppelini Dino MarcoSchlaeger fuer Ballspiele,insbesondere Tennisschlaeger
FR1512401A * Title not available
GB227012A * Title not available
GB228650A * Title not available
GB237395A * Title not available
GB381673A * Title not available
GB450521A * Title not available
GB815921A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3856603 *May 14, 1973Dec 24, 1974Gen Dynamics CorpMethod of manufacturing game rackets
US3930648 *Sep 26, 1974Jan 6, 1976A-T-O Inc.Game racket and stringing means therefor
US3947029 *May 31, 1974Mar 30, 1976N L Industries, Inc.Low density cast racquet
US3966207 *Jun 25, 1973Jun 29, 1976Pass Roger DString system for a game racket
US3981504 *Nov 25, 1974Sep 21, 1976Ppg Industries, Inc.Glass-carbon reinforced foamed resin tennis racket frame
US3986716 *Sep 23, 1974Oct 19, 1976Arundale Manufacturers, Inc.Composite racquet structure
US4099718 *May 17, 1976Jul 11, 1978Marcraft Recreation Inc.Racquet frame construction
US4145047 *May 23, 1977Mar 20, 1979Nippon Gakki Seizo Kabushiki KaishaRacket
US4165071 *Jan 5, 1976Aug 21, 1979Frolow Jack LTennis racket
US4192505 *Nov 7, 1977Mar 11, 1980Pepsico, Inc.Game racket
US4194738 *Jun 26, 1978Mar 25, 1980Hitachi Chemical Company, Ltd.Frame of a game racket
US4291574 *Mar 26, 1979Sep 29, 1981Frolow Jack LTennis racket
US4303238 *Feb 9, 1978Dec 1, 1981Arcadia Air ProductsDiving board with enhanced tip performance
US4348025 *Jan 21, 1981Sep 7, 1982Half Court Tennis Pty. LimitedRacquet
US4664380 *Feb 4, 1985May 12, 1987Siegfried KueblerRacket having thickened shaft portion
US4768786 *Feb 24, 1987Sep 6, 1988Siegfried KueblerTennis racket
US4903967 *Jan 27, 1989Feb 27, 1990Ferrari Importing Company, Inc.Racket frame having holes for tailoring frame stiffness
US4911444 *Mar 4, 1988Mar 27, 1990Yonex Kabushiki KaishaTennis racket
US4919438 *Jun 10, 1988Apr 24, 1990Yonex Kabushiki KaishaTennis racket
US5005834 *Mar 16, 1990Apr 9, 1991Ferrari Importing CompanyMulti-frame racket
US5037098 *Feb 7, 1990Aug 6, 1991Prince Manufacturing, Inc.Tennis racquet with tapered profile frame
US5048830 *Sep 20, 1990Sep 17, 1991Lo Kun NanRacket frame with shock absorbing characteristics
US5062634 *Aug 31, 1990Nov 5, 1991Wilson Sporting Goods Co.Squash racket
US5071124 *May 3, 1990Dec 10, 1991Prince Manufacturing, IncBadminton racquet
US5143370 *Jan 6, 1992Sep 1, 1992Rammer, Inc.Ball racket
US5211396 *Feb 19, 1991May 18, 1993Ferrari Importing CompanyMulti-frame racket
US5538243 *Mar 14, 1994Jul 23, 1996Sumitomo Rubber Industries, Ltd.Tennis racket frame
US5540434 *Aug 21, 1990Jul 30, 1996Wilson Sporting Goods Co.Tennis racket
US6062994 *Apr 10, 1998May 16, 2000Ef Composite Technologies, L.P.Reinforced racquet with flat string bed
US6447412Apr 18, 2000Sep 10, 2002Ef Composite Technologies, L.P.Sports racket with undulations in frame interior surface
US6572498Mar 28, 2001Jun 3, 2003Larry J. NeversBall launching racket
US6958104Aug 20, 2002Oct 25, 2005Ef Composite Technologies, L.P.Sports racket with undulations in frame interior surface
US7044869Mar 30, 2004May 16, 2006Head Technology GmbhRacket for ball games and production process
US8092323 *Aug 16, 2010Jan 10, 2012Michael RigoliSports equipment stick with truss construction
US9192822Nov 27, 2012Nov 24, 2015Wilson Sporting Goods Co.Optimized thermoplastic racquet
US9199135Nov 27, 2012Dec 1, 2015Wilson Sporting Goods Co.Optimized thermoplastic racquet
US20030190986 *Apr 9, 2003Oct 9, 2003Nevers Larry J.Ball launching racket
US20050164813 *Mar 30, 2004Jul 28, 2005Johannes MauserRacket for ball games and production process
US20070270256 *May 17, 2006Nov 22, 2007Jinan Kesavan ChullikattuSports racquet
US20110053715 *Aug 16, 2010Mar 3, 2011Michael RigoliSports equipment stick with truss construction
USRE31419 *Jan 28, 1981Oct 18, 1983 Tennis racket
CN100402114CMay 19, 2005Jul 16, 2008弗尔克尔网球有限公司Sport racket
DE3716708A1 *May 19, 1987Dec 8, 1988Lo Kun NanSchlaeger mit einem verbesserten halsbereich
DE3723628A1 *Jul 17, 1987Jan 26, 1989Licentia GmbhMicrowave oven
DE102004003528B3 *Jan 23, 2004Jul 21, 2005Head Technology GmbhRacket for ball games, e.g. tennis, squash, badminton or racket ball comprises a racket head and a frame with a connected grip section
EP0310169A2 *Sep 17, 1985Apr 5, 1989Siegfried KueblerRackets for ball games, especially tennis rackets
EP1557203A2Dec 20, 2004Jul 27, 2005Head Technology GmbHRacquet for ball sports and method for its manufacture
WO1980002510A1 *May 17, 1979Nov 27, 1980J FrolowTennis racket
WO1989006558A1 *Jan 18, 1989Jul 27, 1989Pols Erik Bernard V DTennis racket
WO1990009213A1 *Jan 22, 1990Aug 23, 1990Ferrari Importing Company, Inc.Racket frame having holes for frame stiffness
Classifications
U.S. Classification473/535, 273/DIG.100
International ClassificationA63B49/14, A63B49/10, A63B49/02
Cooperative ClassificationY10S273/01, A63B49/06, A63B2049/0211, A63B2209/026, A63B49/14, A63B59/0014, A63B49/10
European ClassificationA63B49/10, A63B49/14