US2009265A

US2009265A - Production of tennis and like racket frames

Info

Publication number: US2009265A
Application number: US661166A
Authority: US
Inventors: Hirschfield Alexander
Original assignee: Individual
Current assignee: Individual
Priority date: 1932-03-23
Filing date: 1933-03-16
Publication date: 1935-07-23
Anticipated expiration: 1952-07-23
Also published as: GB402434A

Description

July 23 19350 A. HIRSC HHHH LD 2,009,265

OF CKET FRAMES Jul1y23, 135. A. HIRSCHFHELD 20@9265 PRODUCTION OF TENNIS AND LIKE RACKET FRAMES Filed March 16, 19s: 4 Sheets-Sheet 2 July 23, 1935. A. HIRSCHFIELD 2,009,265

PRODUCTION OF TENNIS AND LIKE RAGKET FRAMES Filed March 16, 1955 4 Sheets-Sheet s July 23, 1935. A. HIRSCHFIELD PRODUCTION OF TENNIS AND LIKE RA CKET FRAMES 4 Sheets-Sheet 4 Filed March 16, 1953 Patented July 23, 1935 UNITED sTATEs PRODUCTION OF TENNIS AND LIKE RACKET FRAMES Alexander Hirschfield, London, England Application March 16, 1933. Serial No. 661.166 In Great Britain March 23, 1932 6 Claims.

This invention relates to the production of composite wooden articles, particularly tennis, badminton, squash or like frames.

The usual method of making these racket frames by bending a solid piece of wood is a slow,

costly and diflicult process and, on account of atmospheric conditions and influences, the racket frames have a tendency to warp and twist so that the rackets are rendered useless after a comparatively short period of use. This usual process of making rackets is also costly on account of the large amount of waste timber involved, even after a selection of prime wood, and involves a large proportion of rejects from the finished articles. The process, involving as it does a bending of each racket frame separately, is also a slow one.

With a view to overcoming the above disadvantages of racket frames made from solid wood some manufacturers have attempted to produce laminated racket frames by gluing together several pieces of wood. In the production of these laminated racket frames, however, wet glue has been relied upon to cause adherence of the plies and this has resulted in the imparting of additional moisture to the plies and the consequential easy tendency for the rackets produced to warp or twist. Further, it is difficult to effect a uniform distribution of a wet glue over the surfaces of the plies, so that the gluing strength of the glue joints is impaired.

The present invention has for its objects to provide composite wooden articles, particularly tennis and like racket frames which will be free from the above disadvantages while enabling their manufacture upon an economical and commercial basis.

In the production of a laminated tennis or like racket frame or other laminated structure which requires that a definite shape should be imparted thereto in accordance with the present invention an adhesive is employed which, initially, is disposed between the plies in a dry condition but which will cause the plies to adhere closely and firmly together upon the application of heat and pressure thereto, which pressure in addition to affording the pressure necessary to effect a complete adherence of the plies by the adhesive also serves to produce the requisite shaping of the plies.

The invention also provides greatly improved methods and means of producing racket frames, or other composite wooden articles in accordance with the previous paragraph and also provides improvements in connection with the actual construction of these articles, as will now be fully described with reference to the drawings and set out in the appended claims.

In the accompanying drawings:

Figure 1 is a perspective view of a composite structure in accordance with the invention and from which a plurality of racket frames may be formed.

Figure 2 is a perspective view of a tennis racket frame according to the invention;

Figure 3 is a perspective view of a completed tennis racket, made in accordance with the invention;

Figure 4 is a fragmentary view of a detail;

Figures 5, 6 and 7 are perspective views of different wedges provided by the present invention for use in the manufacture of racket frames.

Figure 8 is a diagrammatic perspective view of a press for completing a composite structure of the form seen, for example, in Figure 1, and

Figures 9, l0 and 11 are views of an actual press provided for this purpose, Figure 9 being a front elevation, Figure 10 a fragmentary plan, and Figure 11 a cross section on the line AA of Figure 10.

In carrying the invention into effect in one convenient manner as applied, for example, to the production of tennis or like racket frames, the latter are formed from a composite structure which, itself, is composed of a plurality of thoroughly dried plies of a suitable wood united together by an adhesive. This composite structure is shaped so as to provide the conventional ring I of a racket frame and the handle 2 thereof, While a wedge 3 is also provided at the throat of the said ring. A composite structure, as seen in Figure 1, serves for the production of a number of racket frames (of which one is seen in Figure 2) by slicing the structure longitudinally.

All the parts of the structure are caused to adhere to each other in the required relationship by the use of an adhesive which normally is in a dry condition and is known as a dry film glue, being in fact a synthetic glue. This glue, being obtainable in sheet form, is admirably suited to the carrying out of the invention, sheets of this glue being interposed between the adjacent plies and heat and pressure being applied to effect a fusing of the glue sheets and a firm adherence of the plies without the addition of any moisture thereto after the definite position of the interposed plies has been reached by pressure.

The wedge 3 is separately formed and in general is composed of three segments, each of which may consist of a single piece of wood or be built up from plies of a suitable wood. Thus in Figure 5 a wedge is shown composed of three segments 5, 6, I, each of which is composed of a plurality of wooden plies arranged so that those of the top section I. follow generally the shape and grain of that portion of the ring I where this part of the wedge is to be located in the completed frame, while the plies of the side sections 5, 6 are arranged generally longitudinally of the handle 2 in the direction of the grain of the latter.

The wedge shown in Figure 6 is composed of three segments united together and to a central rod 1 and these segments are formed from single blocks of wood arranged so that the grains thereof follow generally the shape of the ring or handle parts of the racket frame as in the previously described wedge. In some cases it may be desired to omit the central rod 1 and provide a wedge of the construction shown in Figure 7 which otherwise is similar to the wedge illustrated in Figure 6. A separate piece of wood 8 composed of one or more plies is secured to the top of the wedge, which piece forms a reinforcement at the throat of the racket ring I, and has portions 9 thereof extended beyond the sides of the wedge and adapted to be secured to the corresponding inner surfaces of the ring part 2, as is clearly seen in Figures 1 and 2. The correct shaping of the side surfaces of the wedge segments may be effected by holding the wooden blanks (from which these segments are formed) in suitable jigs and subjecting the exposed portions of the blanks to the action of appropriately shaped spindle cutters.

The wedge segments are assembled, together with pieces of dry film glue disposed so as to lie between the surfaces of the wedge segments to be joined together, and having assembled the wedge parts together in correct relationship they are inserted into a press where they are permanently secured together by a fusing and setting of the adhesive and the reinforcement piece 8 is then secured to the top and exposed surface of the wedge by an intervening piece of dry film glue so that a complete wedge unit of a depth corresponding with that of the said composite structure is thus formed ready for transportation bodily to another press in which the formation of the composite structure aforesaid is completed and which will be described later.

The ring and handle parts I, 2 respectively of the racket frames are, as will be appreciated from consideration of the foregoing, produced from plies of wood which prior to their insertion in the press are, together with sheets of dry film glue disposed between the adjacent plies, bent into a substantial U-formation and held in such form by a jig which grips the free ends of the sheets. The so assembled sheets are thus readily transportable to the said second press which binds the sheets together and is illustrated in Figures 8 to 11. Having placed the assembled plies in this press the said jig may be removed leaving the bent sheets free to be pressed into the required form. This preliminary bending of these sheets is readily accomplishable by laying the sheets of wood and film glue upon a horizontal table having a central opening into which the sheets are moved so that they are formed into a substantially U-formation by means of a vertically reciprocable ram which engages and bears upon the middle portion of the sheets disposed across the opening. Having operated this ram so to deform the sheets the free ends of the sheets (i. e. the ends of the U) which are left projecting upwardly above the said table are clamped together by said Jig.

As previously mentioned the dry film glue employed for carrying out this invention is obtainable in sheet form. Actually this sheet material is supplied in roll form and for the purpose of cutting strips of this material from a roll thereof, which. strips shall be of the required dimensions (approximating those of the separate piles of wood), an apparatus may be employed which comprises a table to suit such dimensions and upon which table the strips of adhesive material may be severed from the roll.

Referring now to Figures 8 to 11 and in the first instance to the diagram (Figure 8) this U-shape assembly of plies and sheets of dry film glue (indicated generally by the reference ID) are shown arranged within the said second press together with a wedge unit completed in the above described manner (this wedge being indicated generally by the reference I) and a central handle piece [2 and outside handle pieces I3, all of which parts are firmly united to each other in the desired relationship by the operation of the press parts. These comprise, essentially, a central former I 4, a head platen I5 and pairs of side platens l6, l1 and I 8. The said platens, which are adapted to be heated, and also the central former M, are operated in sequence so that the bending of the assembly l0 takes place progressively from the apex of the U thereof towards the ends thereof thereby allowing for any longitudinal movement of the said assembly under the pressure of these platens and obviating the formation of any wrinkles in the finally pressed assembly. Thus the head platen l5 would be operated first followed by the side platens I6, I! and ill, in the order mentioned, the two platens of each pair moving together. The former I4 is adapted for vertical movement so as to leave the table of this press free to receive the assembly Hi. In the specific press illustrated in Figures 9 to 11 the former I 4 is adapted to be raised and lowered by the hydraulically actuated ram I9, the platens Hi to I8 being also hydraulically actuated, and this former will be lowered into its position within the assembly of plies l0 prior to the commencement of the sequence of operations of said platens. As previously mentioned the former l4 and each of the platens are heated, this being effected, for example, by steam applied to each platen by a pipe 20 and circulated through a coil 2| within each platen, said pipe communicating with one end of the coil and the other end of the latter communicating with another pipe 22 which serves to lead away the condensate. The former i4 is similarly heated so that all parts of the racket frame structure are subjected to that amount of heat and pressure (which pressure is conveniently hydraulically applied) necessary to cause the glue to bind the parts of the structure together firmly.

The wedge 3 is held in position in the press, prior to its becoming united to the assembly In, by the bottom end of the wedge being seated within a recess 23 provided in the table 24 and the top end of the wedge being held within. a corresponding recess 25 provided on a removable plate 26 so that the wedge may be lowered endwise into this position. The table 24 is also provided with a longitudinal recess 21 in which the bottom edge of the central handle piece I2 is adapted to be received and held in position for attachment to the corresponding inner surfaces article with the least possible waste.

of the handle forming part of the said assembly It by pieces of .dry film glue disposed between these surfaces and the surfaces of such piece [2. The press as seen in Figure 11 is adapted for the reception of a wedge unit of the construction seen in Figure 6, the central rod 1 and the throat reinforcement 8 being also indicated in Figure 11, but by arranging for the said plate 26 to be removable and by providing the bottom wedge recess 23 in a removable part of the press table 24 also, the press may be adapted to accommodateany shape of wedge which may be required while by arranging for the former l4 and the platens l5 to l8 to be removable these may be changed so that the press may be adapted to produce a composite structure having whatever outline may be required, for example, that of a' tennis, badminton or squash racket. The outside handle pieces l3 may be arranged in position within the press just prior to the closing of the last pair of platens l8 they being subsequently taken up by these platens and pressed firmly thereby against the corresponding outer surfaces of the handle forming part of the said assembly I0, pieces of dry film glue being also disposed between these surfaces and the inner surfaces of the said pieces l3. When the above sequence of operations of the press has been completed and the necessary amount of heat and pressure applied the former I4 is raised and the platens withdrawn so that the formed structure may be removed from the press, this structure being now of the form seen in Figure 1. The structure is then sliced longitudinally, as previously mentioned, same being centered and guided upon a suitable jig during this slicing operation, whereafter each of the racket frames produced from the structure has another strip of wood 28 (Figure 3), similar to the pieces l3, secured to the top and bottom sides of the handle portion thereof. This adherence of the strips 28 may be effected in another hydraulic press comprising a series of horizontal plates between which the handles of the racket frames may be clamped with the said strips positioned therebetween and which plates may be heated so as to complete the adherence of the strips to the handles by pieces of film glue disposed between the strips and handle surfaces. These

side pieces

13 and 28 provided on the racket frame handles enable the latter to be finished to the desired form.

The racket frames are now ready for the conventional finishing operations, including stringing thereof, but instead of employing the conventional screw for maintaining security at the neck of the racket frame I prefer to employ a rivet 29 (Figures 3 and 4) for this purpose.

Among the many advantages obtainable with the present invention it may be mentioned that it enables a mass production of a high class The composite block above mentioned, representing multiples of some 20 frames, is the largest of its kind yet attempted to produce in one single pressing and embodies at the same time the special three-piece wedge and adjoining inner reinforcing band as well as the handle and handle sides. In view of their special construction, the racket frames are uniform in quality and will not warp and twist, rendering the usual press unnecessary.

After the plies have been dried down to a minimum moisture content, no moisture is added during the whole manufacturing process, the interposing grain of the veneers being sealed after being pressed into definite position through high hydraulic pressure and under great heat.

The glue joints are indissoluble in water, or on account of dampness or moisture, and inseparable through strain, apart from being insect proof through certain ingredients contained in the glue. This renders the rackets or other articles produced particularly adaptable for use in varying climates, especially the tropics. The glue, apart from its extraordinary waterproofness and strength, is elastic and, in combination with the numerous plies of wood, makes the articles very resilient.

A great advantage in the construction of artlcles according to the invention lies in the fact that after the frames thereof leave the press (1. e. the press seen in Figures 8 to 11) no seasoning is required and they can be finished at once ready for use. This saves the locking up of capital for a considerable time, and waste of material through finding seasoned rackets out of shape and useless. On account of the considerable strength of the frame, the balancing of same, by the customary method of removing material from the frame, represents no difficulty. The special rivet devised, that takes the place of the ordinary, screw, also adds greatly to the strength of the racket in that it offers a firmer grip without cutting into, and damaging, the material of the racket in the manner of the conventional screw.

I claim:

1. A method of making a tennis and like racket frame from veneers which consists in assembling together the separate veneers with an adhesive in a dry state between them andwhile the adhesive is still in a dry unfused state bending the veneers into a substantial U-shape and then applying pressure and heat simultaneously to bend the veneers into the shape of the frame, fuse the adhesive and cement the veneers together.

2. A method of making a tennis and like racket frame from veneers which consists in superimposing upon one another a plurality of veneers separated from one another by loosely inserted sheets of dry unfused glue and subjecting the so assembled sheets into a substantial U-shape and then applying pressure and heat simultaneously to bend the veneers into the shape of the frame, fuse the adhesive and cement the veneers together.

3. A method of making a, tennis and like racket frame from veneers which consists in superimposing upon one another a plurality of sheets of veneer separated from one another by loosely inserted flexible sheets of dry glue having a uniformly distributed glue content and, while the glue is still dry and unfused, bending the so assembled veneers, together with the sheets of glue, into a substantial U-shape and then applying pressure and heat simultaneously to bend the veneers into the shape of the frame, fuse the adhesive and cement the veneers together.

4. A method of making a tennis and like racket frame from veneers which consists in superimposing upon one another a plurality of sheets of thoroughly dried veneer separated from one another by intermediate flexible sheets of dry film glue having the glue content thereof distributed evenly over their entire surfaces and while the sheets of glue are still in a dry state bending them, together with the veneers, into the shape of the frame and simultaneously with the bending operation subjecting the veneers to heat so 4 aooaaes as to melt the glue and cause the bent veneers to be cemented together, the bending of the veneers and the uniting thereofbeing accomplished without adding moisture to the veneers.

5. A method of making a tennis or like racket frame which consists in superimposing upon one another a plurality of sheets of veneer separated from one another by flexible sheets of glue in a dry state, bending the sheets of veneer and dry glue into substantially .u -form, inserting a wedge within the U together with a layer of glue, in a dry state, disposed on the outer edge surfaces of the wedge, again bending the sheets of veneer and dry glue so as to close the U onto the wedge and bend the veneers into the shape of the frame wedge to be cemented to the bent veneers at the throat of the frame.

6. An extension of the method according to claim 5 which consists in arranging a. 'sheet of veneer within the U together with sheets of glue in a dry state-on each side surface thereof and securing this veneer sheet at the centre of the handle part of the frame during the completion of the formation thereof.

ALEXANDER HIRSCHFIELD.