Title:
TENNIS RACKET HANDLE HAVING LONGITUDINAL DISPLACEMENT
United States Patent 3633910
Abstract:
The invention refers to tennis rackets in which the frame is formed of two superposed tubes or rods bent to the desired shape, each comprising a pair of rectilinear parallel extensions, the two superposed pairs forming the handle portion of the frame. According to the invention the superposed pairs are connected with each other by means permitting a slight longitudinal respective displacement of a pair with respect to the other when the handle portion flexes in use. In an embodiment the pairs are connected by stays having four perforations for passage of the extensions, these stays being alternately welded to one and to the other pair. In another embodiment the stays are welded to both pairs, but they are somewhat resiliently deformable.
US Patent References:
RACKET AND METHOD OF MAKING SAME
Cheris et al. - September 1970 - 3528658
Tennis or squash racket
Robinson - December 1933 - 1937787
RACKET WITH METAL FRAME WELDED TO HANDLE SLEEVE
Palmer - November 1970 - 3540728
RACKET FOR TENNIS OR SIMILAR GAMES
Deer - December 1970 - 3547440
RACKET AND METHOD OF MAKING SAME
Cheris et al. - September 1970 - 3528658
Tennis or squash racket
Robinson - December 1933 - 1937787
RACKET WITH METAL FRAME WELDED TO HANDLE SLEEVE
Palmer - November 1970 - 3540728
RACKET FOR TENNIS OR SIMILAR GAMES
Deer - December 1970 - 3547440
Application Number:
05/017561
Publication Date:
01/11/1972
Filing Date:
03/09/1970
View Patent Images:
Export Citation:
Assignee:
Chervin, Michel (Villeurbanne, FR)
, Santini-ormieres Jean (Lyon, FR)
, Santini-ormieres Jean (Lyon, FR)
Primary Class:
Other Classes:
473/520
International Classes:
A63B49/08; A63B49/12; A63B49/02; A63B49/08
Field of Search:
273/73,75,81
Primary Examiner:
Pinkham, Richard C.
Assistant Examiner:
Apley, Richard J.
Claims:
I claim
1. In a tennis racket having a frame formed of a pair of like symmetrical superposed metallic tubes curved to the profile required for the stringing of the racket, each having a pair of rectilinear extensions substantially parallel to each other and to the pair of extensions of the other tube, said frame further comprising first means to assemble with each other the extensions of each pair, and second means to assemble said pairs with each other, so as to constitute for said frame a resilient handle portion having a zone which flexes when the racket strikes a ball:
2. In a tennis racket as claimed in claim 1, each of said transverse stays being in the form of a substantially rigid plate having four perforations for passage of the extensions of both of said pairs, and the extensions of one of said pairs being welded to said plate.
3. In a tennis racket as claimed in claim 1, said transverse stays being alternately secured to the extensions of one and of the other of said pairs along the length of said zone of said handle portion.
1. In a tennis racket having a frame formed of a pair of like symmetrical superposed metallic tubes curved to the profile required for the stringing of the racket, each having a pair of rectilinear extensions substantially parallel to each other and to the pair of extensions of the other tube, said frame further comprising first means to assemble with each other the extensions of each pair, and second means to assemble said pairs with each other, so as to constitute for said frame a resilient handle portion having a zone which flexes when the racket strikes a ball:
2. In a tennis racket as claimed in claim 1, each of said transverse stays being in the form of a substantially rigid plate having four perforations for passage of the extensions of both of said pairs, and the extensions of one of said pairs being welded to said plate.
3. In a tennis racket as claimed in claim 1, said transverse stays being alternately secured to the extensions of one and of the other of said pairs along the length of said zone of said handle portion.
Description:
DESCRIPTION OF THE INVENTION
The present invention relates to tennis rackets of the kind in which the frame is formed of two superposed metallic rods or tubes which are curved to the usual rounded shape, each having a pair of rectilinear extensions substantially parallel to each other and substantially parallel to the pair of extensions of the other rod or tube, with the extensions of each pair being rigidly assembled with each other by means of transverse stays, so as to constitute the handle portion of the racket frame.
In such rackets the pair of rectilinear extensions are assembled in a rigid manner in the transverse and in the longitudinal direction in order to form a quite strong unit which may resist the high stressed to which the racket is submitted when striking the ball. Experience however demonstrates that in spite of such an arrangement the handle portion thus realized sometimes breaks in use.
An object of the present invention is to avoid this disadvantage and to provide a racket of the kind above referred to which will support the stresses in use without requiring for this purpose an increase in the cross section of the rods or tubes, i.e., in the weight of the racket.
According to the invention, in a racket of the kind above referred to, the pairs of extensions are assembled with each other by means which, while retaining the said pairs with respect to each other in a transverse direction, permit a limited degree of relative movement of these pairs in the longitudinal direction, at least in the zone of the said pairs which flexes when the racket strikes a tennis ball.
It has been ascertained that when a racket of the kind above referred to strikes a ball, the stringing carried by the frame imparts to the latter a bending force which may be considered as situated in the central portion or "heart" of the racket. Under the action of this force the two superposed pairs of extensions are bent elastically with different radii of curvature. When these pairs are rigidly connected with each other in the longitudinal as well as in the transverse direction substantially along their full length, one of them is submitted to compressive stresses and the other to tractive stresses, and these stresses may reach quite high values which the rods or tubes cannot safely support. On the contrary if each pair of tubes or rods remains free to move longitudinally with respect to the other pair in the zone which flexes, these compressive and tractive stresses cannot appear. It has besides been noted that the arrangement which forms the object of the present invention avoids or minimizes the transmission of vibrations to the racket handle. This is an important advantage since these vibrations have an undesirable effect not only on the frame, but also on the user of the racket who may thus suffer from what is called "tennis elbow."
In the accompanying drawings:
FIG. 1 is a perspective view of a racket according to the invention, the handle portion being illustrated without the conventional outer lining.
FIG. 2 is an enlarged longitudinal section through the handle portion illustrated in FIG. 1.
FIG. 3 is a transverse section corresponding to the line III--III of FIG. 2.
FIG. 4 is a side view diagrammatically illustrating the bending of the handle portion of the racket frame during use of the racket.
FIG. 5 is a transverse section similar to FIG. 3, but illustrating a modification.
FIG. 6 is a transverse section taken along line VI--VI of FIG. 5 and illustrating the elastic deformability of the transverse stay shown in this figure.
FIG. 7 is a diagrammatic cross section showing an embodiment wherein the tubular extensions which form the handle portion of the frame are filled with plastic cords.
In the racket illustrated in FIG. 1 the frame is formed of two superposed metallic tubes which are curved so as to realize the usual rounded portion A in which the stringing is mounted, while their ends extend in straight lines, parallel to each other in the form of two superposed pairs of extensions in order to constitute the handle portion B of the frame. The rounded portion A is closed in the vicinity of the "heart" C of the racket by an arcuate member 1, while the rectilinear extensions which constitute the handle portion B are rigidly assembled near this member by a transverse stay 2. This stay 2 is formed of a relatively thick plate (see FIG. 2) provided with four perforations through which the said extension are passed and in which they are thereafter secured in position by welding. Beyond the stay 2, the two pairs of rectilinear extensions are assembled by two other stays 3 and 4
As illustrated in FIGS. 2 and 3, stay 3 is also formed of a relatively thick plate provided with perforations through which the pairs 5 and 6 of rectilinear extensions are passed, but while in the case of stay 2 the latter is rigidly welded to both pairs, stay 3 is only welded to the lower pair 5, the upper pair 6 remaining free to slide through the stay. In FIG. 3 this has been illustrated by exaggerating the clearance 7 left between each extension 6 and the edge of the corresponding perforation of the stay. Of course in actual practice this clearance is on the contrary as small as possible.
The third stay 4 is also similar to stays 2 and 3, the difference being that it is only welded to the upper pair 6 of rectilinear extensions, the lower pair 5 being free of slide longitudinally through this stay.
FIG. 4 illustrates the handle portion of the racket frame when it is submitted to a bending force, namely when the racket strikes the tennis ball downwardly. In such a case the handle portion B flexes elastically with the concavity turned upwardly under the combined effect of the reaction of the stringing and of the action of the hand of the player. The radius of curvature is therefore greater for the lower pair 5 than for the upper pair 6. If all the stays 2, 3 and 4 were rigidly welded to both pairs, this would mean that the extensions of the lower pair would have to expand longitudinally while those of the upper pair would have to contract, which would entail considerable strains applied to the welds with risks of rupture of the walls of the tubes. But with the construction described the upper pair may slide through stay 3 and the lower pair through stay 4. The compressive and tractive stresses are thus fully eliminated. Moreover, owing to the frictional effects which occur between each pair of extensions 5, respectively 6, and the stay 4, respectively 3, through which it is slidable, vibrations are considerable dampened.
In the modification illustrated in FIGS. 5 and 6, both pairs of extensions 5 and 6 are welded to each transverse stay such as 8, but each stay has two lateral slits 8a, each extending horizontally from one side of the stay towards the central portion thereof in a plane situated substantially midway of the pairs of extensions 5 and 6, but terminating short of the other slit. These slits may be considered as dividing the stay into a central portion with four somewhat resilient lugs each welded to an extension 5 or 6. Owing to this resiliency each pair of extensions may move longitudinally to a certain extent with respect to the other pair, as indicated in FIG. 6, without entailing considerable stresses. Of course the stays should be made of a sufficiently resilient metal in order to avoid fatigue phenomena under the action of repeated deformations.
The dampening of vibrations may further be increased by filling the tubular extensions 5 and 6 with an appropriate plastic. As shown in FIG. 7 there may be used for this purpose a cord 9 of a deformable synthetic material having substantially an outer diameter equal to the inner diameter of the said extensions 5 and 6. The racket frame is thus substantially reinforced and the increase in weight of the racket is almost negligible.
The present invention relates to tennis rackets of the kind in which the frame is formed of two superposed metallic rods or tubes which are curved to the usual rounded shape, each having a pair of rectilinear extensions substantially parallel to each other and substantially parallel to the pair of extensions of the other rod or tube, with the extensions of each pair being rigidly assembled with each other by means of transverse stays, so as to constitute the handle portion of the racket frame.
In such rackets the pair of rectilinear extensions are assembled in a rigid manner in the transverse and in the longitudinal direction in order to form a quite strong unit which may resist the high stressed to which the racket is submitted when striking the ball. Experience however demonstrates that in spite of such an arrangement the handle portion thus realized sometimes breaks in use.
An object of the present invention is to avoid this disadvantage and to provide a racket of the kind above referred to which will support the stresses in use without requiring for this purpose an increase in the cross section of the rods or tubes, i.e., in the weight of the racket.
According to the invention, in a racket of the kind above referred to, the pairs of extensions are assembled with each other by means which, while retaining the said pairs with respect to each other in a transverse direction, permit a limited degree of relative movement of these pairs in the longitudinal direction, at least in the zone of the said pairs which flexes when the racket strikes a tennis ball.
It has been ascertained that when a racket of the kind above referred to strikes a ball, the stringing carried by the frame imparts to the latter a bending force which may be considered as situated in the central portion or "heart" of the racket. Under the action of this force the two superposed pairs of extensions are bent elastically with different radii of curvature. When these pairs are rigidly connected with each other in the longitudinal as well as in the transverse direction substantially along their full length, one of them is submitted to compressive stresses and the other to tractive stresses, and these stresses may reach quite high values which the rods or tubes cannot safely support. On the contrary if each pair of tubes or rods remains free to move longitudinally with respect to the other pair in the zone which flexes, these compressive and tractive stresses cannot appear. It has besides been noted that the arrangement which forms the object of the present invention avoids or minimizes the transmission of vibrations to the racket handle. This is an important advantage since these vibrations have an undesirable effect not only on the frame, but also on the user of the racket who may thus suffer from what is called "tennis elbow."
In the accompanying drawings:
FIG. 1 is a perspective view of a racket according to the invention, the handle portion being illustrated without the conventional outer lining.
FIG. 2 is an enlarged longitudinal section through the handle portion illustrated in FIG. 1.
FIG. 3 is a transverse section corresponding to the line III--III of FIG. 2.
FIG. 4 is a side view diagrammatically illustrating the bending of the handle portion of the racket frame during use of the racket.
FIG. 5 is a transverse section similar to FIG. 3, but illustrating a modification.
FIG. 6 is a transverse section taken along line VI--VI of FIG. 5 and illustrating the elastic deformability of the transverse stay shown in this figure.
FIG. 7 is a diagrammatic cross section showing an embodiment wherein the tubular extensions which form the handle portion of the frame are filled with plastic cords.
In the racket illustrated in FIG. 1 the frame is formed of two superposed metallic tubes which are curved so as to realize the usual rounded portion A in which the stringing is mounted, while their ends extend in straight lines, parallel to each other in the form of two superposed pairs of extensions in order to constitute the handle portion B of the frame. The rounded portion A is closed in the vicinity of the "heart" C of the racket by an arcuate member 1, while the rectilinear extensions which constitute the handle portion B are rigidly assembled near this member by a transverse stay 2. This stay 2 is formed of a relatively thick plate (see FIG. 2) provided with four perforations through which the said extension are passed and in which they are thereafter secured in position by welding. Beyond the stay 2, the two pairs of rectilinear extensions are assembled by two other stays 3 and 4
As illustrated in FIGS. 2 and 3, stay 3 is also formed of a relatively thick plate provided with perforations through which the pairs 5 and 6 of rectilinear extensions are passed, but while in the case of stay 2 the latter is rigidly welded to both pairs, stay 3 is only welded to the lower pair 5, the upper pair 6 remaining free to slide through the stay. In FIG. 3 this has been illustrated by exaggerating the clearance 7 left between each extension 6 and the edge of the corresponding perforation of the stay. Of course in actual practice this clearance is on the contrary as small as possible.
The third stay 4 is also similar to stays 2 and 3, the difference being that it is only welded to the upper pair 6 of rectilinear extensions, the lower pair 5 being free of slide longitudinally through this stay.
FIG. 4 illustrates the handle portion of the racket frame when it is submitted to a bending force, namely when the racket strikes the tennis ball downwardly. In such a case the handle portion B flexes elastically with the concavity turned upwardly under the combined effect of the reaction of the stringing and of the action of the hand of the player. The radius of curvature is therefore greater for the lower pair 5 than for the upper pair 6. If all the stays 2, 3 and 4 were rigidly welded to both pairs, this would mean that the extensions of the lower pair would have to expand longitudinally while those of the upper pair would have to contract, which would entail considerable strains applied to the welds with risks of rupture of the walls of the tubes. But with the construction described the upper pair may slide through stay 3 and the lower pair through stay 4. The compressive and tractive stresses are thus fully eliminated. Moreover, owing to the frictional effects which occur between each pair of extensions 5, respectively 6, and the stay 4, respectively 3, through which it is slidable, vibrations are considerable dampened.
In the modification illustrated in FIGS. 5 and 6, both pairs of extensions 5 and 6 are welded to each transverse stay such as 8, but each stay has two lateral slits 8a, each extending horizontally from one side of the stay towards the central portion thereof in a plane situated substantially midway of the pairs of extensions 5 and 6, but terminating short of the other slit. These slits may be considered as dividing the stay into a central portion with four somewhat resilient lugs each welded to an extension 5 or 6. Owing to this resiliency each pair of extensions may move longitudinally to a certain extent with respect to the other pair, as indicated in FIG. 6, without entailing considerable stresses. Of course the stays should be made of a sufficiently resilient metal in order to avoid fatigue phenomena under the action of repeated deformations.
The dampening of vibrations may further be increased by filling the tubular extensions 5 and 6 with an appropriate plastic. As shown in FIG. 7 there may be used for this purpose a cord 9 of a deformable synthetic material having substantially an outer diameter equal to the inner diameter of the said extensions 5 and 6. The racket frame is thus substantially reinforced and the increase in weight of the racket is almost negligible.