GB2218641A - Tennis racket handle pallet - Google Patents

Abstract

An improved tennis racket handle pallet 14 formed of polymeric material has durometer hardness such as to render such handle pallet sufficiently soft for absorbing shocks and vibrations but not so soft as to preclude racket indexing, the handle pallet being of a sufficiently high density so as to minimize the need for employing additional weights to maintain proper racket balance. The racket frame 16 may be formed of aluminium or graphite with glass fibre or ceramics and the pallet of moulded urethane. The handle may be of octagonal cross-section and covered with leather or the like 36. <IMAGE>

Description

TENNIS RACKET HANDLE PALLET This invention relates to tennis rackets with improved handle pallets and, more particularly, to an improved tennis racket handle pallet of a particular durometer to render such handle pallet sufficiently soft for absorbing shocks but not so soft as to preclude racket indexing, the handle pallet being of a sufficiently high density so as to minimize the need for employing additional weights to maintain proper racket balance.

Tennis is considered a sport by some and a game by others. It involves players on opposite sides of a net who employ rackets to strike a resilient ball back and forth over the net. The racket has one end with tensioned strings which contact the ball and another end with a handle grasped by the user. The handle is designed for player comfort and is provided with flat areas and edges along its length so that the player may index the stringed end of the racket without having to observe the position of such strings with respect to the handle.

Traditionally, handles were fabricated of built up layers of material. More recently, however, handles have been molded in one piece of a plastic material. Such molded handles have normally comprise a cellular polymeric material which is foamed in place over the handle end or butt end of the racket frame with the cellular polymeric material constituting the handle pallet and with a leather strip spirally wound thereover. One piece molded plastic handle pallets have reduced their cost of manufacture and have yielded a firmer construction without rattles during use.

Their hardness, however, has been found not to adequately absorb shocks and vibrations to the hand of a player using the racket while striking a ball. Additionally, such known handle pallets are fabricated of rigid cell materials and thus tend to crack and chip.

The background art discloses many types of handles and handle pallets for tennis rackets as well as for other types of hand held devices. To illustrate the wide variety of handles and handle pallets designed for use as tennis rackets, consider the teachings of spiral wound layers as disclosed in U.S. Patent Numbers 4,015,851 to Pennell and 4,159,115 to Ticktin. Separate sleeves for covering handles are disclosed in U.S. Patent Numbers 4,09tri,506 to Gaiser and 3,614,100 to Spitz. Separate sleeves are usually for the purpose of absorbing perspiration. Spector, in U.S. Patent 4,567,091, discloses an adhesive tape usable on handles. In addition, U.S.Patent Numbers 3,489,031 to Myer; 4,284,275 to Fletcher and '1,660,832 to Shomo, show tennis racket handles designed for particular purposes such as aeration, grip enhancement and for shock and vibration abatement.

In addition to handles and handle pallets specifically designed for utility in tennis rackets, tne background art discloses handles designed specifically for use in golf clubs. Note U.S. Patent Numbers 3,606,325; 4,133,529 and 4,338,270 to Lamkin, Gambino, Uffindell.

Lastly, the background art discloses many other types of handles for use in a wide variety of applications.

These include U.S. Patent Numbers 3,915,782 to Davis; 4,053,676 to Kaminstein; 4,174,109 to Gaiser; 4,347,280 to Lauand 4,j73,718 to Schmidt.

The background art discloses a very wide variety of handles and handle pallets designed for use in a wide variety of devices, to perform a wide variety of functions. They are fabricated of a wide variety materials, natural and synthetic, and formed by a wide variety of processes. The older patents disclose the building up of the handles from a variety of constituent materials while the newer patents identify the desirability of the less costly molded handles.

The background art discloses handle pallets which are sufficiently soft to absorb shocks and vibrations during hitting, handle pallets which are sufficiently hard to allow for indexing of the racket strings, and handle pallets of a density sufficient to maintain racket balance. No background art, however, discloses, teaches or suggests a tennis racket with an improved handle pallet as described herein to provide in one unit all of these desirable features, along with greater convenience of manufacture and at a reduced cost.

All known handles and handle pallets are simply lacking in one regard or another.

As illustrated by the background art, efforts are continuously being made in an attempt to improve tennis racket handles. No prior effort, however, suggests the present inventive combination of component elements arranged and configured as disclosed and claimed herein. Prior handles do not provide the benefits attendant with the present invention. The present invention achieves its purposes, objects and advantages over the prior handles through a new, useful and unobvious combination of component elements, through the use of a minimum number of parts, through the utilization of readily available materials and conventional components and at a reduction in cost to manufacture.

It is, therefore, an object of the present invention to provide a pallet handle usable on the frame of a tennis racket, the handle pallet having a cross-sectional configuration with flat sections extending along its length for indexing of the racket by the user, the handle pallet being fabricated of an elastomeric polymer having a Shore A hardness of about between 60 and 80, and more preferably 60 and 70, to absorb shocks and vibrations during use while still retaining its indexing capabilities, the polymeric material having a density of about between 8 and 10 pounds per cubic foot to minimize the need for the addition of weights in order to attain proper balance of the racket on which it is used.

It is a further object of the present invention to absorb shocks and vibrations to the user during the striking of balls by a tennis racket.

It is yet a further object of the present invention to maintain the ability of users to index a tennis racket during play without having to observe the position of the strings with respect to the handle.

Further it is an object of the present invention to make tennis racket handles of a dense material which minimizes for the need for weighting of the racket handle portions in order to maintain racket balance.

The foregoing has outlined some of the more pertinent objects of the invention. These objects should be construed as merely illustrative of some of the more prominent features and applications of the present invention.

Many other beneficial results may be attained by applying the disclosed invention in a different manner or by modifying the invention within the scope of the disclosure. Accordingly, other objects and advantages as well as a fuller understanding of the invention may be had by referring to all of the disclosures in the present application, Those disclosures include the description and the appended claims, abstract, and drawings, In some example of the present invention, the invention may be incorporated into a handle pallet for use in a tennis racket frame, the handle pallet having a cross-sectional configuration with flat sections extending along its length for indexing of the racket by the user, the handle pallet being fabricated of polymeric.

material having a Shore A hardness of about between 60 and 80, and more preferably about 60 and 70 to absorb shocks and vibrations during use while still retaining its indexing capabilities, the polymeric material having a density of about between 8 and 10 pounds per cubic foot to minimize the need for the addition of weights in order to attain proper balance of the racket on which it is used.

Further, the invention may be further incorporated into an improved handle for use on a tennis racket frame.

The handle has a pallet molded onto the frame at the handle in a cross-sectional configuration with a plurality of flat sections and edges extending along its length for indexing of the racket by the user, the handle pallet being molded of a dense, soft, elastomeric polymeric material for absorbing shocks and vibrations during use while still retaining its indexing capabilities, the polymeric material having a heavy density sufficient to minimize the need for the addition of weights in order to attain proper balance of the racket in which it is used. The polymeric material has a durometer of about between 60 and 80 on the Shore A scale. The polymeric material pallet preferably has a durometer of about between 60 and 70 on the Shore A scale. The polymeric material, most preferably, has a durometer of about 65 on the Shore A scale.

The polymeric material has a density of about between 8 and 10 pounds per cubic foot. The polymeric material, most preferably, has a density of about 9 pounds per cubic foot.

The polymeric material of the pallet is cast from a mixture of isocyanate and polyol. The mixture may include a ratio of about 95 parts isocyanate to about 100 parts polyol, which mixture is hand cast to form the pallet. The mixture may also include a ratio of about 1.00 parts isocyanate to about 1.26 parts polyol, which mixture is automatic machine injected to form the pallet. The molded material is of uniformly varying density with the greater density being adjacent to the exterior and interior surfaces and the lesser density being at the central region of the material.

Lastly, the invention may be incorporated into a tennis racket comprising a frame with a bow end and a handle end. The frame is fabricated from the class of frame materials including aluminum, graphite and mixtures of graphite. The handle end includes a pallet molded onto the frame in a cross-sectional configuration with a plurality of flat sections and edges extending along the length of the pallet, the pallet being molded of a dense, soft urethane having a durometer of about between 60 and 80 on the Shore A scale. The mixtures of graphite include graphite/glass, graphite/Kevlar, graphite/ceramic and others. The urethane of the pallet preferably has a durometer of about between 60 and 70 on the Shore A scale. The urethane of the pallet, most preferably, has a durometer of about 65 on the Shore A scale.The urethane of the pallet, preferably, has a density of about between 8 and 10 pounds per cubic foot. The urethane of the pallets most preferably, has a density of about 9 pounds per cubic foot. The handle also includes a strip of material spirally wound about the pallet. The pallet as molded includes voids with entrapped gasses wherein such voids with entrapped gasses are more extensive adjacent to the frame central region of the pallet.

The foregoing has outlined rather broadly the more pertinent and important features of the present invention in order that the detailed description of the invention that follows may be further understood whereby the present contribution to the art may be more fully appreciated. Additional features of the invention will be described hereinafter within the scope of the present invention. It should be appreciated by those skilled in the art that the conception and tne specific embodiment disclosed herein may be readily utilized as a basis for modifying or designing other apparatus for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent apparatus does not depart from the invention as set forth in the appended claims.

The present invention is illustrated by the following detailed description taken in conjunction with the following drawings in which: Figure 1 is a perspective illustration of a tennis racket utilizing the handle and handle pallet of the present invention in the form of one example; Figure 2 is a cross-sectional view of the handle and handle pallet of the tennis racket taken along line 2-2 of Figure 1; Figure 3 is a cross-sectional view of the handle and handle pallet taken along line 3-3 of Figure 2; and Figure 4 is an enlarged illustration of a portion of the handle pallet as shown in Figure 3.

Similar numerals refer to similar parts throughout the various views.

wood, rubber, plastic, cloth, etc. in various configurations.

Spiral wound layers were often utilized. Such a fabrication technique led to irregularities in construction and "feel" from one racket to another and increased rattles during use.

The cost of effecting such laying of materials was also found to be excessive. More modern tennis rackets reduced the cost of materials and fabrication and increased their consistency of quality by utilizing a plastic material molded onto the racket frame at the handle end or butt end. Unfortunately, however, such newer handles were always of an excessively hard material, with a Shore D hardness of 110 to 80 plus, whereby forces generated by striking a ball would generate shocks and vibrations which were transferred to the user thereby causing discomfort. Over the course of a game, set or match, such repeated vibrations and shocks would be fatiguing to the user resulting in a continuing decrease in the user's efficiency of play.

The present invention utilizes an elastomeric polymeric material as the handle pallet 14, preferably a urethane, molded to the frame 16 at the butt end or handle end 20. The pallet handle has been found to function with frames, not only of graphite, but also of other materials including aluminum and mixtures of graphite such as Shown in Figure 1 is what appears to be a conventional tennis racket 10 but which is provided with the improved handle 12 and handle pallet 14 of the present invention. The tennis racket 10 is fabricated of a frame 16 having a head end 18 and a handle end 20. Adjacent the head end 18 is an opening 24 across which strings 26 are secured under tension to constitute the hitting surface 28. Either side of the strings may constitute the hitting surface.

Located at the handle end 20 is the handle 12 for being gripped by the user of the racket 10. As is conventional in the art, the handle 12 is provided with a plurality of flat sections 30 extending longitudinally along the handle. Edges 32 separate the flat section 30. In the preferred embodiment, the handle 12 takes an octagonal cross-sectional configuration with eight flat sections 30 and eight edges 32.

A spiral wound layer 36, as of leather or the like, covers the handle pallet 14 for improved grippability.

As is the practice in the more modern tennis rackets, the frame 16 is preferably fabricated of some percentage of graphite fibers in the conventional manner. In the past, handles were fabricated of built up components of graphite/glass, graphite/Kevlar, graphite/ceramic, or other similar materials.

The exterior surface of the molded urethane is about between 60 and 80 on a Shore A scale. A durometer of about between 60 and 70 on a Shore A scale is preferred. A durometer of about 65 on a Shore A scale is most preferred.

The exposed exterior surface as well as the interior surface of the molded pallet form smooth skins of similar characteristics and durometer. The interior region of the foam material which forms the pallet decreases in hardness proportionately with a minimum hardness of about 30 to 70, preferably 65, at its central extent. A urethane of such hardness and molded as described herein has been found to absorb or dampen the shocks and vibrations which would normally occur with handle materials previously known and utilized.

The hardness of this preferred handle pallet material has an added benefit beyond the vibration and shock abatement. Specifically, when such a handle 12 is gripped by a user in a normal fashion during the play of tennis, the user will deform the handle material slightly. Such deformation, however, has been found to be insufficient to effectively eliminate the flat sections 30 and edges 32 molded into the cross-section of the handle. Such flat sections 30 and edges 32 may still be "felt" by the user. As a result, without looking at the racket 10 and its strings 26, the user will be able to "feel" the flat sections and ridges and, therefore, be able to index the hitting surface 28 of the racket 10 to a proper angular orientation with respect to the ball to be struck.If a racket with a softer handle pallet were utilized, the user could grasp the handle and effectively obliterate its flat surfaces and edges so that the handle would "feel" like a round cross-sectional handle. In such case, indexing would be impossible.

Handle pallets softer than those of the present invention would result in inferior play by the user. Handle pallets harder than those of the present invention would result in increased fatigue an injury by the user, again resulting in inferior play.

The elastomeric nature of the cells of the urethane allows the handle and handle pallet of the present invention to recover and return to its prior preferred shape after use.

The handles and handle pallets of the background art had a rigid cell structure and would tend to retain their new shape after deformation. In prior art rigid cell structures, the individual cells transmit energy in a form of vibration. In the structure of the present invention, the flexible cell structure absorbs the energy effected through ball striking and, hence, such vibrations are not transmit-ted through to the user for more comfortable and less fatiguing use.

Another feature of the racket of the present invention is that the material of the handle pallet 14 has a higher density than those molded with materials previously known and utilized. Because of this, the weight of prior art handle end 20 is insufficient to maintain the proper weight and balance of the racket 10 between head end 18 and handle end 20. The density of the preferred materials is in a range of about between 8 and 10 pounds per cubic foot. The most preferred density is about 9 pounds per cubic foot. When prior molded handles were utilized, their higher durometer material resulted in a handle 12 of lighter weight. As a result, added weighting components were normally inserted into the handle so that the resulting racket would have better balance between the head end 18 and the handle end 20.

When lighter materials were utilized without the added weights, the performance of the user would be inferior due to racket imbalance. While weights could be added to the interior of the handle to correct the problem, such weights often became loose and would shift during play thereby causing "buzzing" and second vibrations. This resulted in even further deterioration in the play of the user. With the denser material of the present invention, the handle 12 can be designed to optimize the balance and "feel" of the racket between bow or head end 18 and the butt or handle end 20 for improved play by the user. The need for weights is thus minimized.

The pallet 14 for the handle 12 of the tennis racket 10 of the instant invention may be molded in any one of several techniques. Two types of molding which have been successfully performed include a hand casting and an automatic machine casting. In accordance with the hand cast method, a ratio of 95 parts isocyanate to 100 parts polyol on a weight basis are used. The materials are mixed well and heated to between 110 and 120 degrees Fahrenheit. The materials are then combined in a paper cup and mixed again about between 15 and 20 seconds using a wooden tongue depressor. The mold is charged with about 80 grams of the mixture. The mold is clamped tightly and rotated with the handle end of the frame 16 in proper position within the material. The molded part is then demolded 5 minutes later.

Finished parts weighed an average of about 60 and 70 grams now at proper temperature. After sitting for 12 to 18 hours, they give a Shore A hardness of about between 60 and 80. The mixing is done with a drill press or with a power mixer, air or electric, in an open cup which gives much more uniform results.

In the automatic machine injection technique, which could also be performed by hand, isocyanate at a pressure of 62 pounds and at a temperature of 120 degrees Fahrenheit is mixed with a polyol at 120 degrees Fahrenheit and at 170 pounds pressure. The materials are combined in a ratio of one part of isocyanate to 1.26 parts polyol at a temperature of between 65 and 80 degrees Fahrenheit. A machine such as an Admiral 122-p low pressure cast machine is utilized.

Mold time is 5 minutes with pour time being 1.60 seconds.

Cream time is 7.5 seconds, gel time 13.0 seconds, rise time 35.0 seconds and tack-free time 80-100 seconds. The freerinse density is 30 to 31 pounds per cubic foot. The molds are of the epoxy type with any wax-based mold release agent.

Such molds may also be fabricated of steel or aluminum. A typical handle pallet weighs about between 60 and 70 grams at proper temperature and has a specific gravity of 0.6-0.65 grams per cubic centimeter.

When fabricated as disclosed herein, the molded pallets will form voids with entrapped gasses throughout the polymeric material and thus constitute a foam. Such voids with entrapped gasses will be less extensive at the interior surface contacting the frame and at the exterior exposed surface. The voids with entrapped gasses will be more extensive at the central region of the pallet. Note Figure 4. The greater the extent of the voids, the less will be the density and hardness. The lesser the extent of the voids, the greater will be the density and hardness. The molded polymeric material of the pallet handle will thus be of uniformly varying density with the greater density being adjacent to its exterior and interior surfaces and the lesser density being adjacent to the central region of the pallet.

The greater density at the exterior surface adds to the rigidity and relative hardness of the surface of the handle pallet in the ranges as defined hereinabove to enhance the indexing capabilities of the racket. The greater density and hardness of the pallet adjacent to the frame presents a smooth surface or skin, thinner than the skin on the exposed surface, which maximizes contact therebetween. Such an interface facilitates the transfer of vibrations from the frame through the handle to the user for increased absorption of vibrations during use. The interior skin is also tough to preclude wear at this interface over extended use. The lesser density intermediate the surfaces adds to the softness and elasticity of the handle at a location away from the surfaces whereby the absorbing of shock and vibration dampening occurs remote from the players hand for increased comfort and efficiency.

Although this invention has been described in a preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made by way of example only and that numerouschanges in the details of construction and the combination and arrangement of parts may be resorted to without departing from the scope of the appended claims.

Claims (22)

1. A handle pallet for use on a tennis racket frame, the handle pallet having a cross-sectional configuration with flat sections extending along its length for indexing of the racket by the user1 the handle pallet being fabricated of polymeric material having a Shore A hardness of about between 60 and 80 to absorb shocks and vibrations during use while still retaining its indexing capabilities, the polymeric material having a density of about between 8 and 10 pounds per cubic foot to minimize the addition of weights in order to attain proper balance of the racket on which it is used.

2. For use on a tennis racket frame, an improved handle having a pallet molded onto the frame at the handle end in a cross-sectional configuration with a plurality of flat sections and edges extending along its length for indexing of the racket by the user, the handle pallet being molded of a dense, soft, elastomeric polymeric material for absorbing shocks and vibrations during use while still retaining its indexing capabilities, the polymeric material having a heavy density sufficient to minimize the need for the addition of weights in order to attain proper balance of the racket on which it is used.

3. The handle of claim 2, wherein the polymeric material has a durometer of about between 60 and 80 on the Shore A scale.

4. The handle of claim 2 or 3, wherein the polymeric material has a durometer of about between 60 and 70 on the Shore A scale.

5. The handle of any of claims 2 to 4, wherein the polymeric material has a durometer of about 65 on the Shore A scale.

6. The handle of any of claims 2 to 5, wherein the polymeric material has a density of about between 8 and 10 pounds per cubic foot.

7. The handle of any of claims 2 to 6, wherein the polymeric material has a density of-about 9 pounds per cubic foot.

8. The handle of any of claims 2 to 7, wherein the polymeric material of the pallet is cast from a mixture of isocyanate and polyol.

9. The handle of any of claims 2 to 8, wherein the mixture includes a ratio of about 95 parts isocyanate to about 100 parts polyol, which mixture is hand cast to form the pallet.

10. The handle of any of claims 2 to 9, wherein the mixture includes a ratio of about 1.00 parts isocyanate to about 1.26 parts polyol, which mixture is automatic machine injected to form the pallet.

11. The handle of any of claims 2 to 10, wherein the molded material is of uniformly varying density with the greater density being adjacent to its exterior and interior surfaces and the lesser density being at the central region of the material.

12. A tennis racket comprising a frame with a bow end and a handle end, the frame being fabricated from the class of frame materials including aluminum, graphite and mixtures of graphite, the handle end including a pallet molded onto the frame in a cross-sectional configuration with a plurality of flat sections and edges extending along the length of the pallet, the pallet being molded of a dense, soft urethane having a durometer of about between 60 and 80 on the Shore A scale.

13. The tennis racket of claim 12, wherein the mixtures of graphite include graphite/glass, graphite/Kevlar and graphite/ceramic.

14. A tennis racket of claim 12 or 13, wherein the urethane of the pallet hae a durometer of about 60 and 70 on the Shore A scale.

15. A tennis racket of any of claims lk to 14, wherein the urethane of the pallet has a durometer of about 65 on the Shore A scale.

16. A tennis racket of any of claims 12 to 15, wherein the urethane of the pallet has a density of about between 8 and 10 pounds per cubic foot.

17. A tennis racket of any of claims 12 to 16, wherein the urethane of the pallet has a density of about 9 pounds per cubic foot.

18. The tennis racket of any of claims 12 to 17, further including a strip of material spirally wound around the pallet.

19. The tennis racket of any of claims 12 to 18, wherein the pallet as molded includes voids with entrapped gasses wherein such voids with entrapped gasses are more extensive adjacent to the central region of the pallet.

20. A tennis racket handle pallet, having sufficient durometer to be sufficiently soft for absorbing shocks and vibrations but not so soft as to preclude racket indexing, the handle pallet being of sufficiently high density to minimize need for employing additional weight(s) to maintain proper racket balance,

21. A tennis racket, comprising a handle, or handle pallet, of any of claims 1, 2 to 11, and 20.

22. A handle, or handle pallet, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

23, A tennis racket, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.