CA1050581A - Rackets with two parallel strung faces - Google Patents

Rackets with two parallel strung faces

Info

Publication number
CA1050581A
CA1050581A CA245,808A CA245808A CA1050581A CA 1050581 A CA1050581 A CA 1050581A CA 245808 A CA245808 A CA 245808A CA 1050581 A CA1050581 A CA 1050581A
Authority
CA
Canada
Prior art keywords
frame
stringing
racket
strip
apertures
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA245,808A
Other languages
French (fr)
Inventor
Robin M. Blackburne
Original Assignee
Robin M. Blackburne
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to GB1012074A priority Critical patent/GB1470980A/en
Priority to GB2429474 priority
Priority to GB855475 priority
Application filed by Robin M. Blackburne filed Critical Robin M. Blackburne
Application granted granted Critical
Publication of CA1050581A publication Critical patent/CA1050581A/en
Expired legal-status Critical Current

Links

Abstract

Abstract of the Disclosure This invention relates to a games racket, such as a tennis or squash racket, including a handle intended to be held in the hand, and carrying a head having an open marginal frame defining a central opening across which extends tensioned stringing carried by the head frame. Instead of being located in a single plane disposed centrally of and bounded by the head frame, the stringing of a racket embodying this invention is disposed in two generally parallel planes located on opposite sides of the frame, i.e. on opposite sides of the opposite side surfaces of the frame, and separated by a distance approximating the thickness of the frame. An elongate strip of a relatively hard synthetic plastics material extends around the central opening, and in a preferred embodiment, this strip overlies the outer peripheral surface of the frame and is provided with a plurality of stringing-receiving apertures distributed around the central opening, disposed outwardly of the outer peripheral surface, and spanning the opposite side surfaces of the frame.

Description

~he present invention relates to rackets, such as tennis~ squash or badminton rackets or the like, which are provided with tensioned s~ringing which forms the playing surfaces of -Ihe racketsO
Such a racket basically comprises a handle or shaft carrying a head in the form of an open marginal frame, for example a generally oval or circular frame~ defining a correspondingly shaped cen-tral openingO The tensioned stringing extends back and forth across the central opening, and i~
composed of a first group of generall~ parallel string portions, and a second group of generally parallel~string portions extending generally perpendicular to, and interwoven with, the string portions of the first group. The thickness of the marginal frame between the opposite side surfaces thereof, in a direction normal -to the plane of the stringing, is ~ ~ -substantially ~reater than that oE the stringing. Such a racket will hereinafter be referred to as "a racket of the type specified".
In known rackets of the type specified, which are currently commercially available and commor~1y u~ed~ -the , , .
stringing passes through peripherallydistributed apertures in the ~rame, the aperture~, at least at their ends which open through the inner peripheral or inwardl~ facing surface of the frame being located approximately centrally between the ~ opposite side surfaces. ~hus, the frame projects on opposite sides of the single plane containing the stringing, and therefore projects beyond both playing surfaces defined by opposite sides of the ~tringing by a distance approximating ..

2 -.

5~i~
one half of the wid-th of the frame in a direction normal to said plane. The amount of the projection depends upon the type and size of the racket1 and, for example, in a conv~tional full size tennis racke-t, is of the order of ~" from said plane~ When such a racket, which is s-t~ung centrally of its frame, i5 used, anda player miss-hits a ball, and the ball strikes the frame or the strings~'adjacent the frame, i.e.
plays a "wood" shot, the ball i~ deflected from its intended traa~c-tory by the projecting frame, and the player usually loses the point as a result.
In order to reduce the aforementioned disadvantage of conventional centrally strung rackets, it has bee~ proposed to provide a racket of the type specified, wherein the head carries tensioned stringing which is disposed in two generally parallel planes separated by a distance approx mating the thickness of the frame.
~ hus, instead of the stringing, and therefore the playing surfaces defined thereby, being recessed with respect to the surrounding frame, the playing surfaces are generally flush with the frame on opposite sides thereof. Since the projection of' the frame relative to the playing surfaces is substantially reduced, the unintentional de~lection of the ball, which occurs when the eguivalent of a "wood" shot is played, i.e. when the 'ball strikes one or other playing surface directly adjacent or in line with the frame, is reduced, and ball control ' maintained.

- 3 -' , , ~, .

However, the loading imposed on a "double~strung" frame is approximately twice that imposed upon a conventional "sin~le-strun~" or"centrally st~lng" frame, which gives rise -to various problems and disadvantages. It is an object of the present invention to provide an improved racket of th.e "double-such strung"type which avoids or substantially reduces/problems and disadvan-tages~
~hus, from one aspect, the present invention consists in a racket of the type specified wherein the head carries tensxned stringing which is disposed in two generally parallel planes separated by a distance approximating the thickness of the frame~ the head including a structural marginal frame part defining the central opening, and at least one member.overlying and carried by.the structural frame part, and being provided with means to position. said :
tensioned stringing in said two generally parallel, mutually spaced planes~ .
. With this construction, it is unnecessary.to complicate and/or weaken the structural frame part by providing it with .
aper-tures or grooves for receiving and locating the stringin~, 20 . the apertures or grooves being, instead, formed in said at .~ least one overlying member.
~he overlying member comprises a hard, substantially incompressible elongate flexible str1p, for example of a tough synthetic plastics material, which significantly reinforces, and extends peripherally around a major proportion of the outer peripheral surface of, the frame part;, .

., . ' ~50~

for example, at least from a position adjacent one side of -the handle, around the frame part, to a position adjacent the opposite side of the handle. Due to its phys.ical characteristic~ and the fact that it is positively secured to, or frictionally grips, the frame part, the strip forms a lamination, significantly reinforcing the frame part, whilst it is more compatible with the stringing than the material of the frame part.
Although the structural frame part may be specially made, or at least the outer peripheral surface thereof may be specially adapted, to receive the flexible overlying strip~ the strip may be designed to be fitted to the frame, for example, the solid or tubular frame,of a conventional, centrally strung metal racket.
Thus, from another aspect, the invention consists in.
a flexible strip arranged and a.dapted to be assembled in overlying reIation, to the outer peripheral surface of the head frame of a rac~et of the type specified, the strip having a peripheral inner surface cooperable wlth the frame, opposite side surfaces which are spaced apar~ by a distance : approximating the thickness o~ the frame between the opposi~e side surfaces of ~he latter, and having a length such that, when assembled to the frame, the strip extends around the frame for a major proportion of the peripheral extent thereof, the strip being provided with means to receive and locate tensioned stringing which is disposed in two generally parallel planes separated by a distance approximatin~ the thickness of 'he frame.

.. , ' , ~

... . .
,. . . . .................... . .
~, , . , . :

~he means for receiving and locating the stringing may comI~ise apertures or grooves extending between~ ~n~
opening into, the opposite side surfaces o~ the stripO
Alternatively, said means may comprise projections on said side surfaces around which the stringing is anchored.
The flexible strip just defined may be readily assembled and secured to the existing frames of a conventional centrally strung racket after removal of the central stringing thereof and replacement or modification of the racket throat, withou~
modification and consequential weakening of the existing frame.
After assembly of the flexible strip, a strin~ing filament ; is threaded through the apertures, or laid in the groove, in `the flexible strip, and passed back and forth across the central opening, to produce the two sets of tensioned stringing in the two generally parallel spaced planes.
~hus, from another aspect, the invention consists in an accessory or conversion kit for converting a normally centrally strung racket to double stringing, including a - flexible strip as just defined, and a throat piece9 or throat piece adaptor, provided with stringing-receiving ~ apertures dimensioned and arranged to locate the stringin~
:. .
disposed in said two planes~ and adap-ted to replace, or adapt, the throat piece of the racket to be converted.
:
In order that the invention may be more readily understood, reference will now be made to the accompanying drawin6s, in which:

'..
'' ' ' , ' .. . . ... .
,, ;~, . ' : ' ' ' ~igure 1 is a perspective view of a racket embodying the pre~e~t invention;
Figure 2 is a section on the line 2-2 of Figure 1, on an enlarged scale;
Figure 3 is a section on the line 3-3 of Figure 1, on an enlarged scale;
Figure 4 is a fragmentary perspective view of the overlying strip shown in Figure 2;
Figure 5 is a section, similar to that of Figure 2~ of a modified head construction;
Figure 6 is a section similar to that of Figures 2 and 5~ showing the application of an overlying strip embodying the invention to the existing metal frame of a conventionally centrally strung racket, to convert the racket to double stringin~; and ~-~igure 7 is a plan view of a throat piece for use with the~strip of Figure 6.
The racket shown in ~igure 1 ]may, for example, be a .; Tennis racket which is basically formed, for example, moulded or extruded, from a metal such as aluminium or steel, or , alloy thereo~.
: In particular, the racket includes a metal strip, for ~; 20 example an extruded aluminium strip, which is bent ~o that the free end portions form a pair of handle or shaft portions 1a, and the intermediate portion forms the structrual part 1b of a head frame 2. A throat piece 3 is secured between the handle portions 1a where they blend into the structural frame :
part 1b. ~

7 ~- :
' ., - .
, ' .

., ~, . .. . . . . . .. . ...

~5~
As will be apparen-t from ~igure 2, the met~l strip, or at least the part 1b thereof~ is of generally "figure-of-eight" or "dumb-bell" cross-section, and is formed in its peripherally ou-twardly directed surface with a peripherally extending undercut or dovetail recess 1co Overlying the outer periphe~y of the structural frame part 1b is a separate frame~reinforcing member in the form of a flexible strip 4, a portion of which is shown in Figure 4~ ~he strip

4 is molded, extruded or otherwise formed from a substantially incompressible and relatively hard syn-thetic plastics material, such as toughened ~ylon or acetyl butadiene styrene ~referred to hereinafter as ~B~) or other tough plastic or other material. r~he thickness of the strip 4 in a direction normal to the planes of the stringing 5, i.e. the spacing between the opposite side surfaces 4a thereof, approximates the thickness, in~the same direction, of the structural frame part 1b,i.e. the~spacing between the opposite side surfac~s 1d thereof. The radial height of the side surfaces 4a,i.e.
in the planes of the stringin~ or direc-tions parallel thereto, approximat~s that of the side surfaces 1dj and the height of each side surface may, in one specific and non-limiting e~ample of tennis racket, be ~" inchO The inner peripheral surface of the strip 4 has a profile corresponding to tha-t of the outwardly directed surface of the frame part 1h~ and includes a longitudinally extending dovetail projection 4b which interlocks with the recess 1c to retain the strip 4 positively anchored to the frame part 1b. 1`he pro~ection may optionally be provided with one or more lon~itudinal channels 4c which impart resilience to the undercut slde surfaces of the projection of the otherwise non-resilient strip, as well a reducing the weight of the head and saving material.

. .

Stringing-receiving apertures 6 are bored or moulded into the strip 4, between and opening into the side surfaces 4a thereof. In this embodiment, the longitudianl axes of the apertures 6 are generally parallel to each other and perpendicular to -the planes of the s-tringing 5. The cross-section, for example diameter-, of the apertures 6 are gen-erally parallel to each other and perpendicular to the planes of the stringing 5. The cross-section, for example diameter, of the apertures 6 is greater than -that of the single or compound f`ilament, i.e. natural gut or synthetic fibre, of which the tensioned s-tringing 5 is composed, so as to allow the stringing filament to pass therethrough the requisite number of times, l.e., once, twice or three times depending upon the position of the apertures. The apertures 6 are bevelled, at least at their outer ends, and at least where they engage the stringing 5, as indicated at 6a, so as to increase, as much as possible, the radius of curvature of the stringing during its transition from the apertures 6 to the slde surfaces 4a, and to blend smoothly with the side surfaces 4a, thereby to minimise chafing of, and localised stresses in, the stringing. The apertures may additionally be curved, bowed or angled downwardly towards their outer ends as viewed in Figure 2 to reduce the sharpness of the said transition.
The ends of the strip 4 blend into the frame part lb adjacent the handle portions la, and, with regard to Figures 1 and 3, the throat piece 3 is provided with an inner margi-nal portion 3a which is of the same -thickness as -the frame portion lb and strip 4 so as to blend in with, and lie in the same planes as, the side surfaces ld and 4a. The margi-nal portion 3a is also provided with stringing-receiving apertures 6.
`~

_ g _ .. . . .. .. . . . .

The portion 3b of the throat piece ex-tending away from the head may be of any desired thickness or configur-ation, and may be thinner than the portion 3a, as shown, to save weight.

- 9a -' ' " :':. - , , ' s~ o~
The throat piece may be molded or otherwise formed from metal or a toughened synthetic plastics material of sufficient strength to resist the tensional stresses of double stringing, and may, for example, be formed from any of the materials from which the strip 4 may be made, or from a reinforced plastics material.
The stringing filament is passed through the apertures 6 in the frame part la, and throat piece 3 back and forth across the opening surrounded by the frame, 50 as to produce two intercon-nected sets of appropriately tensioned string portions, one set 5a, 5b lying in the plane which is generally flush with the plane of the side suxfaces ld and 4a of the frame part and strip which are uppermost in Figure 1, and the other set 5c, 5d lying in a plane parallel to the plane of the first set 5a, 5b and generally flush with the plane of the opposite side surfaces of the frame part and strip which are lowermost and concealed in Figure 1.
Each set comprises two groups of substantially parallel string portions, the string portions of one group 5a or 5c being generally perpendicular to, and interwoven with, the string portions 5_ or 5d respectively of the other group. The dis- -tribution or mutual spacing of the apertures 6 around the frame 2 are such that the mutual spacing of the string portions in both groups in each set is the same as, or similar to, those of the string portions of a conventional centrally strung racket, although this is not essential. However, in this embodiment unlike conventional stringing, the string portions in both groups extend diagonally, i.e. at approximately 45, to the lonyitudinal axis o~ the racket handle, although the string portions could alterna-tively be disposed generally perpendicular and generally parallel to the longitudinal axis, as in conventional s-tringing.
In any event, additional string portions may be provided, such as those indicated at 5e, . ~

.

58~
disposed adjaaen-t to, and overlying, the frame 2, which portions would not be present in a conventional, centrally strung racket, irrespective of the orientation of the string portions.
Although -the ends of the stringing may be anchored by knots which cooperate with the ou-ter ends of one or more of the apertures 6, since these knots may project from the planes of the side surfaces they could be engaged by, and adversely deflect, a ball striking the frame. For this reason one or more of the apertures may be of stepped cross-section so as -to recieve and anchor the knots totally within the apertures. A~ternatively, the stringing may commence and terminate in knots located at the peripherally outer ends of additional and generally radially extending -aperttlres(nt shown), i-e., apertures extending between and ,1 opening through the peripherally inner surface of the frame part and the peripherally outer surface of the over-lying strip, or between the peripherally inner surface of the throat piece 3 and the peripherally outer surface or a side surface thereof.
Due to the length of the stringing filament required, the stringing is preferably produced ~rom two or more separate lengths of filament. ~or example, one length may be employed to produce the string portions 5_ and 5c, whilst , another length may be employed to produce the portions 5b ', and 5d. although this is not essential, and the racket could be strung with a single continuous filament.
In the embodiment of ~igure 1, the longitudinal axes of the apertures 6 are mutually parallel, and perpendicular to the parallel planes of the sets of string portions, so t tha-t the string portions 5a and 5b of one set diverge , relative to the string portions 5c and 6_ respectively of -the other se-t when viewed in plan. Alternatively, the axes of the apertures could be inclined relative to said planes, so that the string portions of one set are parallel to and aligned with, or alternatively parallel to and offset with respect to, the string portions of -the second se-t, as viewed in plan.
The side surface ld and 4a of the frame part lb and s-trip 4 are substantially flat and coextensive, so that stringing 5 will lie on the side surfaces, although the side surfaces could be recessed to accommodate the stringing if required, or raised locally in the vicinity of the apertures, so that the stringing will be spaced, for example -by approxirnately l/8 inch, from the side surfaces. The ap-ertures 6 are preferably located as near to the outer peri-pheral surface of the strip 4 as possib~Le, for example approximately l/8" or less from the latter surface. Since the frame 2 carries tensioned stringing on both sides there-o-E, it is subject to approximately twice the loading which is imparted to a conventional, centrally strung racket head due to the tension in i-ts string portions, and the structu-ral frame part lb will be dimensioned, or strengthened, to resist this additional loading.
The racket shown in Figures l to 3 may be simply formed by bending a length of the extruded aluminium s-trip to the required shape of the handle portions la and frame part lb.
and then assembling the extruded strip 4 thereto by intro-ducing the dovetail project:ion 4b longitudinally into the recess lc and sliding the strip 4 around the periphery of the frame part lb until it is positioned as _ 12 -; ~ , ' '. "
, ' :: :: . . .

8~
shown. This position is preferably accurately prede-termined by cooperating means, such as shoulders or steps (not showr~).
The dovetail projection 4b may be introduced into the recess lc at the free end of one handle portion la, or may be introduced adjacent one side of the handle where the frame part lb mee-ts the handle, which may require modification of the undercut side walls of the recess lc a-t the zone of insertion. Alternatively, the projection 4_ may be snapped into the recess lc due to the resilience imparted to the ~ -undercut side surfaces of the projection 4b by the channel 4c. The throat peice 3 is permanently secured in place, for example by screws, rivets,; an adhesive, or combinations thereof, or by any other suitable securing means. The strip 4 may be secured in place in a similar way, although this is not essential. The stringing-receiving apertures 6 may be bored in the strip 4 and throat piece 3 after assembly to the frame, although preferably these apertures are formed, for example, moulded in or bored, prior to assembly, The stringing 5, tensioned for example to 55 to 60 pounds or more, is then strung as previously described.
The metal strip, or at least the s-tructural frame part lb thereof, and the flexible overlying strip 4, may -take a variety of different forms. For example, the frame part l_ may be of generally H cross-section as shown in Figure 5, instead of "dumb-bell" section as shown in Figure 2, and the frame part lb and strip 4 may be provided with a parallel-sided interfitting recess lc and projection 4b, In this case, the frame part lb and strip 4 may be secured together by securing means as previously described, or may be simply retained assembled together by virtue of the tensioning in the stringing 5.

~s~
By employing a flexible strip of the type described existing conventional, cen-trally strung rackets may be converted to double stringing, and this may be achieved without any modification of the existing conventional frame. The conversion is of particular application to metal framed rackets, for example, those designed by the Maark Corporation of Cranbury, New Jersey, U.S.A., and Figure 6 shows this conversion as applied to a "dumb-bell"
section frame as disclosed in their British Patent No:
1,311,925. The conversion is achieved by removing the con-ventional central stringing, and attaching a flexible strip 7~similar to the strip 4, to the outer peripheral surface of the metal structural frame part 8. This flexible strip is manufactured as an accessory or separate entity, and is profiled as shown so as to fit the contours of the existing frame part 8. In particular, the strip 7 is provided with a continuous rib 7a which locates in a corresponding channel 8a in the outer peripheral surface of the frame part, the rib 7a being optionally formed with bosses 7b which engage in some or all of the conventional stringing-receiving aper-tures 8b in the central web of the frame part. The bosses 7b serve to locate the strip 7 relative to the framé part, and the strlp may additionally be held in place by any of the securing means previously described, or merely by the stringing 5. The strip 7 is pro~ided with stringing-re-ceiving apertures 9 and double stringing as previously described.
The existing throat piece of the centrally strung rac-ket will, in all probability, no-t be suitable for double stringing. In this event, the packaged accessory or conversio~ ~it as marketed will include not only the required length of s-trip 7 or e~uivalent1 but also a suitable double stringing thloat piece such as the throat piece 3 shown in Figure 7, which may, for example9 be similar to the throat piece ~ previously described, to replace the exis-ting throat piece of the convent~nal racketO Alternatively, an appropriate adaptor may be provided for the existing throat piece.
~he existing frame or structural part of conventional, centrally strung rackets as just described may possess the drawback that it lS of insufficient streng~h to withstand double stringing. However, this drawback is eliminated or alleviated since the overlying strip 7 or equivalent, since it .
is made from a relatively hard and incompressible materia}, significantly reinforces or form a structural p~rt of, the frame. ~his reinforcing effect could be enhanced by forming the overlying strip from, or reinforcin~ it with, a reinforcing matsrial~ such as graphite or carbon fibre, or associating it with a metal strip~ wire or wires which may be embedded in the overlying strip, and positively securin~ the overlyinG strip to t;he frame, so that the strip becomes a lamination forming an integral part of the frame. ;
- ~
- 15 - ~

... ... . .. ..
,:

Double-strun~ rac1cets embo~ying this invention, possess numerous advantagesO
In conventional, centrally strung rackets in whtch the stringing-receiving apertures are bored, after formation of the frame, between the inner and outer peripheral surfaces of the frame, these aperturesp which are up to ~0 in numb~r, have to be bored from up to 80 different directions. In addition, the outer peripheral surface of the frame, at least in some regions thereof 9 must be routed or grooved between apertures, to receive the stringing and protect it from damage, for example when the frame is s-truck against the ground.
~or these reasons, hand-made conventional frames are difficult and expensive to produce, as are mass-produced frames due to the complexity and cost of the mass production machines required to simultaneously bore aper-tures from up to 80 different directions and to effect the routing. Furthermore even if the frame is of molded construction,the conventionally placed apertures would similarly render it relatively complex ~and costly, from a pxactical point of view, to mould the frame in one piece~
With the double strung racket embod~ing the invention~
however, the metal strip forming the structural frame part 1b and handle portions 1a may be mass produced, i.e. extruded or moulded, in straight lengths to the required profile, and ~ simply C1lt to len~th and bent to the reguired outline. ~he costly process of drillin~ or boring stringing-receivin~
aperture~ in the frame part is therefore totally eliminated, the strength Or the frame part is not impaired hy the provision ol ~ly strin~in~ receiving apertures, and the design or configuration o~ the frame part is not limited by, or dependent upon the need to provide, such apertures, : .

.......

The plastics overlying strip 4 may likewise be mass produced by extrusion or moulding to the required profile, and the stringing-receiving aper-tures may be formed during this production, or s~lbseguen-tly, ei-ther before or af`ter assembly of the s-trip 4 to t;he frame part 1b~ When the apertures are preformed, appropriate steps will be taken to ensure that they will be correctly and accurately positioned around the frame pa~t after assembly of the strip 4. The throat piece 3 may likewise be mass produced by mouldin~ or any other appropriate process, with or without the stringing-receiving apertures pre-formed therein.
The overlying strip 49 irrespective of whether it is secured in place permanently, e.g. by an adhesive, temporarily, e.g. by reIeasable fRsteners1 or merely held in place by the strin~in~, may be readily replaced when restringing~due to wear or changes in design, whilst retaining the same basic ~structural frame part 1b.
Due to the smoo-th, round-edged outer peripheral surface of the frame which is preserved by the strip, the airflow around the frame during play is improved, and drag is reduced.
In the illustrated embo~iments~ the stringing is cushioned or isolated from the struct;llral part of the frame, particularly where the strin~ing-receiving apertures open into the side surfaces of the frame and the radius of curvature of the stringing is relatively tight, by the overlying strlp 4 formed of a plastics or other material which,although it is substantially incompressible and -~
relatively hard so that it will form a composite laminated structure wi-th, and therefore significantly reinforce, the ~0 frame, is more compatible with the stringing than the , s~

materi.al of ~le structural frame part 1b. '~his tends to reduce chafing or other wear of the stringing, and reduces or distributes localiæed stresses. This is of particular significance when, as illustrated, the frame is made of metal, which is less compatible with the stringing than is wood.
Since the stringing passes through apertures extending between the opposite side surfaces, not the peripheral surfaces, the risk of damage if the frame strikes the ground, is avoided without the expense of routing necessary in conventional rackets.
In ball games played within the confines of a walled court 9 such as Sguash, in which the racket frame of-ten strikes the walls, the use of a racket employing a metal frame which is exposed at its outer periphery is often forbidden, due to the substantial risk of damage, for example, chipping, of the court walls, duè to the racket frame striking the walls ~his risk is eliminated or substant:ially reduced by the provision of the overlylng strip 4, as is the risk of injury :
to a player when struck by a racket:. In addition, the strip 4 cushions the metal frame part~ and eliminates wear thereof, when the frame strikes the walls or floor of the court, and any resultant éxcessive wear or damage of the strip 4 merely nece~sitates the replacement of the strip, not of the-whole racket O
It will be understood that various modifications may be made without departing from the scope of the present inventlon as defined in the appended claims.

- 18 ~

.
, ., 8~
For example, the axes of the stringing-receiving apertures may be inclined relative to the planes of the playing surfaces, to produce two sets of string portions which are mutually parallel, instead of divergent as shown, whilst employing -the stringing technique as herein described and shown. The string portions may, in this case, be either precisely aligned when the frame as viewed in plan, i.e. in a direction perpendicular to the planes of the ~ets of string portions, or staggered so that the string portion of one set lie half way between the string portions of the o-ther set.
Alternatively, the aforementioned parallel stringing may be achieved without inclining the axes of the stringing receiving apertures, by employing a different strlnging technique. In this technique, the stringing filament is passed through a first aperture, across a first side surface of the frame, across the opening in the frame to the opposite or second aperture, though this second aperture from said first side surface to the second side surface, across the opening to, and through, the first aperture, from the second side surface to the firs-t surface, along the first side sur-Eace to the next adjacent or third aperture, through -the third aperture to the second side surface and across the opening to the opposite or fourth aperture adjacent the second aperture, through the fourth aperture and across the opening to, and through, the third aperture to the second side surface~ and along the second side surface to and through the next adjacent fifth aperture. This procedure is repeated to complete the strlnging. It will be apprecia-ted that this ' stringing -technique will require at least some of the stringing-receiving apertures to be of enlarged cross-section to accommodate the additional passes of the stringing.
The foregoing parallel stringing technique produces the string portions of the two sets alternatively. However the parallel stringing could be achieved by producing the string portions of one set and then o-f the other set. I~
this technique, the stringing filament is passed through a first aperture, across a first side surface, and the opening in the frame, to and through a second opposi-te aperture -to the second side surface, along the second side surface to the next adjacent or third aperture, through the third aper-ture to the first side surface and back across the opening to the opposite or fourth aperture next to the first aper-ture, through the fourth aperture to the second surface and along that surface and through to the next adjacent fifth aperture. This procedure is Gontinued to complete the string portions of one set, and is then repeated to produce the string portions of the other set.
In some games, it would in theory be advantageous to be able to play some types of strokes or shots with string~
ing tensioned to a par-ticular value or range, and to play other strokes with stringing tensioned to a higher or lower value. This can be achieved by, and -the feature incorporated in a double strung racket embodying this inven-tion, since, for example by employing the stringing technique just des-cribed, the string portions of one set can, during stringing be readily tensioned to a higher or lower value than that of the string portions of the other set.

.. , : ' : ' ' ' :: ' : .

~59~9S~
As has already been mentioned, frames of double strung rackets must be able to withstand considerably higher stresses than conventional rackets, since the forces -to which the frames are subjected due to the tensioning in the two sets of string portions are approximately doubled. For this reason, apart from modifying the dimensions, cross-sectional shape or other design features of -the frame, or the structural part thereof, to withstand these increased forces, when the frame is formed from a material or materials possessing increased strength may be employed. For example, conventionally employed, i-t is envisaged that o-ther materials the frames may be formed in whole or ln part from, or may be reinforced or combined with, materials such as carbon or graphite fibres, or molybdenum fibres, or the like, or glass fibres in varying proportions to provide the required rigidity, always bearing in mind theStrength/cost ratio.
The overlying strip shown in the drawings!~may extend along the recess in the handle portions in addition to the frame part, and in this event the strip may extend to the free ends of the handle portions, or may terminate adjacent or under the hand grip carried by -the handle portions. The strip, where it extends along the handle portions, may be reduced in height by removing all or part of the aperture-containing part thereof, so that the strip will provide a substantially smooth contour to, and blend in with, the peripherally outer surfaces of the handle or shaf-t portions.
Although the overlying strip 4 shown in the drawings preferably extends continuously around the frame from oppo-site sides of the handle, the single strip 4 may be replaced by two or more, for example in a plurality of, spaced strip or insert portions, each provided with one or more s-tringing-receiving .

5~

apertures, bosses, or other stringing anchoring or accommodating means. The strip or strip portions may have the same side surface-to-side surface thickne~ a~ th~
frame, or may be thicker or thinner.
Instead of providing the illustrated me-tal-framed rackets with a separate overlying strip, the strip could be built up on, or bonded to, the frame part 1b.
The frame part and/or the handle portion may be made from, or include, metal, for example cast aluminium or.
other light-metal or alloy, laminated wood, synthetic plastics material~ carbon fibre, glass fibre, or any other suitable material, or comblnations thereof.
Although the stringing is preferably located in stringing-receiving aper-tures which extend between and ope~ -through the opposite side surfaces of the overlying strip 4 :.
or equivalent? the apertures could be replaced by grooves in the outer peripheral surface and/or one or both side surfaces o~ -the strip 4, in which the s-tringing is located and laid. When the frame possesses sufficien-t strength, the strip or ~trips may be omitted, and the stringin@,-: receiving grooves would then be formed directly in -the outer peripheral and/or one or both side surfaces of the frame~
~When the frame possesses sufficient strength, the :
stringing-receiving apertures,preferably bevelled or other- ~. ~
25 wise blended or shaped at their outer ends, may be formed .~ .:
in the frame or structural frame part thereof, instead of in a peripherally overlying strip as specifically described and illustrated~ For example, when khe .. -~
structural frame part is of tubular.form, made, for 30 example from metal~ or a "pultruded" reinforced plastics material as described hereinafter, the apertures may be _22 _ " , ,, . , ; , , ;. , : . .: :: , , " ; , ., ,: ~ . , , ,. :" ,. , " ", . . .
..

~315a~

located generally centrally between the inner and outer peripheral suraces of the tubingl for example diametrically in the case of circular-cross section steel or other metal tubing.
~he apertures, when formed directly in the frame as just described, may be lined with linings or sleeves of ma-terial more compatible wi-th the stringing than the metal or other material of the frame. In onesuch embodiment, press-fitted or bonded into each aperture from opposite ends thereofj are two separate insert members or grommets formed from a relatively hard and incompressible plastics material, such as toughened Nylon or ABS, or from a resilient material such as a natural or synthetic rubber or any other suitable material.
Each insert member comprises a tubular body terminating in an annular washer-like head at its outer end which surrounds the aperture in the frame and abuts the adjacent side surface of the frame~ These insert members serve to protect thè
stringing from chafing against the relatively hard material of the frame, and the washer-like heads thereof serve to space the s-tringing away~from the side surfaces, for example by ~ inch. If required, the washer-like heads could be omitted, and a single Iength of sleeving could extend through each aperture and partly overly the opposite side surfaces of the frame.
The assembly of the individual grommets or inserts to the individual apertures in the frame may be a tedious and I;ime consurning operation. This may be ~lleviated, and the frame may be simultaneously significantly reinforced, by moulding the inserts, or groups of the inserts, integrally with an interconnectin~ web, the web being joined to, or - . , ~ , f~ S8~.
replacing, the washer-like heads of the inserts.
Alternatively, the washer-like heads may s-tand proud of the web to form washer-like heads serving to space the stringin~ from the web. The mutual spacin~ of the inserts will correspond to the mu-tual spacing of the apertures, and the web will be curved, or capable of being flexed, to correspond to the curvature of the frame as viewed plan~ i.e.
as shown9 in effect, in Figure 1, and may define a closed or continuous loop. Thus, by superimposing such a web on each side surface of the frame, the bodies of the integral inserts will he approximately aligned with their associated apertures, and may be readily pressed into their apertures, either ~uccessively or simultaneously, until the web, which may be coextensive with the side surface, lies on the latter.
When sald inserts are provided,irrespective of whether they are separate, or joined by a web~ the apertures in the frame need not be bevelled or otherwise finished, the bevelling and finish being provided in the inserts.
The webs with their integral inserts, or eguivalent apertured strips which may simply replace -the latter, may be made from a frame-reinforcing material other than these hereinbefore referred to, such as glass fihre or a reinforced plastics material, and may be bonded to opposite side surfaces of the frame so as to enhance reinforcement of the latter. Such webs or strips could also be bonded to conventional frames, for example~ wood frames to convert the frames to double stringing whilst reinforcing said frames to resist the increa~ed loading.
Such webs or strips, which may take -the form of a pair of closed loops, may each be extended so as to be of _ 21~ _ .
.; ' 51~3~

generally L-shaped cross section, so tha-t the base of the L
overlies a side surface of the frame, and the side limb of the L overlies up to one half of the width of the outer peripheral surfaces~ Alternatively, the webs or strips could each be of ~enerally U-shape instead of L-shape, the side limbs overlying up to one half of the width of the inner and outer peripheral surfaces of the frame.
Thus, in bo-th cases, the webs or loops form half shells which are bonded -to, and clad, ~he frame, further increasing the strength of the frame.
When the apertures are formed direc-tly in the frame - and the frame is ~rmed from laminated material, for example from wood and/or glass fibre and/or plastlcs and/or metal, the pla~es of the laminations may extend generally perpendicular to the planes o~ the stringing 6, as in conventional laminated racket frarnes. In this event, the apertures should preferably be bored ou-twardly of, but adjacent a relatlvely hard lamlnation, such as a glass fibre lamination. However, the frame may alternatively and advan-tageously be laminated flat, i.e. the planes of some or all of the laminat~ns may extend generally parallel to the planes of the stringin~. This form of lamination should be superior to conventional lamination9 since the apertures extend generally perpendicular to the planes of the laminations, and the tension in the stringin~ acts in directions general]y parallel to the planes o~, and the -major dimensions ol`, the laminations~
When the ape~tures are formed directly in the frame as prev~usly described, since the apertures extend parallel or ~ubstantially parallel to each other between opposite side surfaces of the frame, the formation o~ the apertures, _25 -which may be effected by boring, drilling, pressing, stamping, punching or moulding, is a relatively ~imple, rapid and cheap operation, whether carried out manually or automatically.
When carried out auto~atically, the apertures may be formed by means of a multi-head or multi-spindle machine, instead of the far more complex machinery employed in conventional racket automated manufacture.
When the frame is moulded, it may be moulded in one piece, and the apertures may be formed at the same time, or subsequently.
It will be appreciated that the foregoing are only some of the many alternative stringing techniques or configurations which may be employed. The stringing-receiving apertures~grooves or equiv~ent stringing-accommodating means, may likewise take a variety of forms and cross-sections, and be disposed in various positions and extend in various directions.
As an alternative to providing the peripherally overlying strip with stringing-receivlng apertures as described with~
reference to -the drawings, the strip coul~ be provided with integral or assembled bosses or eguivalent around which the stringing is looped, located and anchored. The webs or strips provlded on the side surfaces of the ~rame in the previously described alternative but non-illustrated embodiment, could also ~e provided with such bosses, or with stringin~-receiving grooves, or e~uivalent.

.. .... - .

The frame or frame part could be made from materials and by techniques other than those herein described. For example the frame or frame part could be made from a -tube or tubes formed -from glass fibre rein-forced thermo-se-tting resins, possibly reinforced with continuous and/or over-lapping chopped carbon -fibres, by ex-trusion, or by a "pultrusion" technique in which, as opposed -to ex-trusion, the tube, or integral group of two or more tubes, is pulled from the forming die. The tubing is formed to the required frame outline whilst still hot and formable from the die, whereafter it sets to its final outline. For example three tubes may be simultaneously and integrally formed, the tube configuration being such that as viewed in cross section, the centre of the central tube is coincident wi-th the base or intersection of the side limbs of an imaginary V, and the centres of the other tubes are coincident one with each of ~the side ~imbs. With this configuration, the tubes will ., . ~ .
define an undercut channel which would serve to receive an undercut projection on an overlying strip, in a manner analogous to that described with reference to Figures 1 to 4.
~ lternatively, the frame, when formed from laminations, could include one or more in-termediate layers of an expanded rigid foam, such as expanded polystyrene, polyurethane or other foam or "honeycomb" material, bounded by relatively hard laminations, for example of a carbon fibre-reinforced resin. By varying the densi-ty of the foam, the weight of the racket head ma~ be predetermined.
The expanded foam or honeycomb could be preformed to the outline of -the racket head and handle or shaft -to form a core therefore, and could be bonded to and clad wi-th two generally U-section half shells~ each in the form of a continuous loop and integral handle portion formed from the aforementioned relatively hard lamination material, and each shell forming one side surface and half the thickness or widl;h of the inner and outer peripheral surfaces of the frame and handle. The shells may be apertured before or after bonding to the core to form -the stringing-receiving apertures~ may be provided with inwardly direc-ted tubular bosses, and/or washer-like heads, or may he provided with bosses around which the stringing is anchored, similar to those just describedO
The foregoing honeycomb,laminated or sandwich constructions are strong, particularly in torsion and bend.
The frame, frame part~ inserts, overlying strip or ~ -web, and/or throat piece, or at least the stringing-engaging regions thereof, may be formed from carbon fibre-reinforced nylon, since the presence of the carbon fibre in this composite can significantly reduce the coefficient of frlction of the composi-te~ and thus reduce the wear of the stringing due to chafing on the composite. Stringing i~ also facil~ated, since the string portions may more easily slide through the apertures during threadine and tensioning.
,.'", ~ ,-. -. .

Claims (9)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-
1. A games racket comprising a handle intended to be held in the hand, and carrying a head having an open marginal frame defining a central opening, across which extends tensioned stringing carried by the head, the stringing being composed of a first group of generally parallel string portions, and a second group of generally parallel string portions extending generally perpendicular to, and interwoven with, the string portions of the first group, the thickness of the frame in a direction generally normal to the plane of the stringing being substantially greater than the thickness of the stringing, the frame including a structural marginal frame part defining the central opening, and a separate flexible but substantially incompressible, elongate member having an upper portion and a lower portion and formed from a relatively hard synthetic plastics material, extending substantially continuously, at least from one side of the handle, around the outer peripheral surface of said same part to the other side of the handle, and overlying said outer peripheral surface, said frame part and said lower portion of the elongate member having at least one interfitting projection and recess, said elongate member being formed with a plurality of stringing-receiving apertures distributed around a major proportion of the peripheral extent of the frame, said apertures being spaced from the outer periphery of said upper portion of the elongate member, and extending continuously between and opening into, opposite side surfaces of said elongate member which are spaced apart in said direction, said elongate member, in the zones thereof provided with said apertures, having a thickness in said direction approximating the thickness of said frame part, and at least the outer peripheral surface of said upper portion of the elongate member, over substantially its entire length, being relatively smooth, uninterrupted, and devoid of protections, said tensioned stringing carried by the head passing through said apertures, and being disposed in two generally parallel planes separated by a distance approximating the thickness of the frame in said direction.
2. A racket as claimed in claim 1, wherein the interfitting projection and recess are of interlocking dovetail configuration, said recess being formed around said frame part in the outer peripheral surface thereof, and said strip member being formed with said projection.
3. A racket as claimed in claim 1, wherein said elongate trip extends continuously around the outer peripheral surface of the frame part and at least part way along the handle, wherein the frame part is substantially devoid of stringing-receiving apertures, wherein the strip is of generally uniform cross-sectional profile throughout substantially its entire length and wherein the stringing lies closely adjacent the opposite side surfaces of the frame.
4. A racket as claimed in claim 1, wherein the height of the opposite side surfaces of each said frame part approximate the height of the opposite side surfaces of said elongate strip.
5. A racket a claimed in claim 1, wherein said relatively hard synthetic plastics material is selected from the group consisting of toughened Nylon and acetyl butadiene styrene.
6. A racket as claimed in claim 5, wherein the axes of said stringing-receiving apertures are mutually generally parallel, and generally perpendicular to the planes of the stringing.
7. A racket as claimed in claim 1, wherein the frame is formed from an extruded aluminium strip of generally "H"
or "dumb-bell" cross section, and wherein, at the juncture of the frame and handle, there is secured a separate throat piece forming a continuation of the side surfaces of the frame, the throat piece being moulded from a relatively hard plastics material.
8. A racket as claimed in claim 1, provided with a tubular steel frame, and wherein, at the juncture of the frame and handle, there is secured a separate throat piece forming a continuation of the side surfaces of the frame, the throat piece being moulded from a hard plastics material.
9. A racket as claimed in claim 1, wherein the axes of said stringing-receiving apertures are generally parallel to the axes of adjacent apertures, and wherein said axes are inclined relative to the planes of the stringing, whereby the first and second groups of string portions in one of said generally parallel planes extend in directions parallel to the directions of the string portions in the first and second groups, respectively, in the other of said generally parallel planes.
CA245,808A 1974-03-06 1976-02-16 Rackets with two parallel strung faces Expired CA1050581A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
GB1012074A GB1470980A (en) 1974-03-06 1974-03-06 Rackets
GB2429474 1974-05-31
GB855475 1975-02-28

Publications (1)

Publication Number Publication Date
CA1050581A true CA1050581A (en) 1979-03-13

Family

ID=27255223

Family Applications (1)

Application Number Title Priority Date Filing Date
CA245,808A Expired CA1050581A (en) 1974-03-06 1976-02-16 Rackets with two parallel strung faces

Country Status (1)

Country Link
CA (1) CA1050581A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4655455A (en) * 1985-06-05 1987-04-07 Shozo Kurusu Sports Rackets
US4804183A (en) * 1987-03-11 1989-02-14 Robert H. Redkey Double faced sports racquet
US4844478A (en) * 1988-05-24 1989-07-04 Milton Kessler Racket game for beach and kit therefor
US5423532A (en) * 1993-08-20 1995-06-13 Huang; Hung C. Double-strung game racquet and method for stringing

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4655455A (en) * 1985-06-05 1987-04-07 Shozo Kurusu Sports Rackets
US4804183A (en) * 1987-03-11 1989-02-14 Robert H. Redkey Double faced sports racquet
US4844478A (en) * 1988-05-24 1989-07-04 Milton Kessler Racket game for beach and kit therefor
US5423532A (en) * 1993-08-20 1995-06-13 Huang; Hung C. Double-strung game racquet and method for stringing

Also Published As

Publication number Publication date
CA1050581A1 (en)

Similar Documents

Publication Publication Date Title
US10737148B2 (en) Golf club head having a composite crown
JP6167240B2 (en) Golf club head with polymer face
US4793616A (en) Golf club
US20170001082A1 (en) Golf club head having a composite crown
US7044870B2 (en) Blade for hockey stick or the like
US5346213A (en) Golf club head
DE3507640C2 (en)
US5346216A (en) Golf club head
US5547189A (en) Golf club and club shaft constructions
US4812187A (en) Method of manufacturing a golf club head
US5288070A (en) Golf club head of composite material
US3642283A (en) Magnesium tennis racket with weighted throat piece
US6273830B1 (en) Tapered hollow shaft
FI113624B (en) Process for making one to one hockey club and a shaft
US5716291A (en) Golf club shaft
JP4294982B2 (en) Ball bat
US7867114B2 (en) Multi-walled tubular baseball bats with barrel inserts of variable geometry
US5542222A (en) Corner post support member
CA1129453A (en) Games rackets
US7789774B2 (en) Golf club head having a displaced crown portion
US6123353A (en) Method of joining and reinforcing molded plastic bicycle frames
US4204681A (en) Game ball racket wherein certain racket components are structurally integrated with the racket frame by the string with which the racket is strung
US20110036489A1 (en) Hockey Stick
CA1069147A (en) Hockey stick
KR100416051B1 (en) Long tennis racket