US2373899A - Method for manufacturing balls for games - Google Patents

Description

April 17, 1945: L a LEJEUNE 2,373,899

METHOD FOR MANUFACTURING BALLS FOR GAMES Origina l Filed Jan. 12, 1959 L lo 82 /9 Patented Apr. 17, 1945 1 UNITED STATES PAT ENT- OFFICE g amass g Leon Max Sylvaln laieune, Paris. France; vested in the Allen Property Oustodlan Original application January 12, issasemi No.

Divided and thls application September 29, 1939, Serial No. 297,182. In France August 9, 1938 "4 Claims. v

tions imposed by regulations which are in more or less distant relationship with the requirements of the game itself.- The manufacturer has to give the ball a, certain hardness through inflation; when the ball impinges on the racket, the initial velocity of the ball remains very high, but is immediately afterwards reduced by the braking action on the felt hairs of the coating. which action increases with the length of these hairs and reversely.

It will be noted that t e ball does not'remain the same throughout its existence as it lets .out its airslowly and thus has a decreasing initial velocity. The felt hairs shorten and become less close by reason of the wear of the felt. The ball is thus progressively less energetically braked and bounces higher so that the initial conditions, viz: high initial velocity, braked speed in air and slow reception on the racket are transformed in an irregular manner. The two drawbacks constituted by the air let out of the ball and by the wear of the felt cover, render the life of the ball very short and irregular.

I may conclude in stating that the balls now in use do not assista good player and do not allow the entire possible progress of tennis playing as regards rapidity and regularity'of play.

The short life of the balls used to this day makes the game expensive whereasin contradistinction my improvedball has entirely different properties and advantages.

In the first place my improved ball cannot let 'its air out for the simple reason that it isnot inflated.

This ball has a constant bounce which does not vary with the temperature. Its initial speed has a constant very high value which remains the same during the whole life of the ball. There is no damping effect noticeable upon impinging on the ground as in the case of felt so that the speed remains very high between the ground and the receiving racket. The bounce from ground to racket is thus a rapid and regular one as there is no wear of felt. The ball is easily visible by reason of its constant whiteness. the ball being washable. It is sensitive neither to cold, nor heat, nor dampness and ,remainstherefore unaltered in any weather.

f This ball is chiefly characterized by the as that its cover is constituted by a textile impregnated throughout with rubber. This ensures a rigidity such that it is possible to do away on one hand with any outer textile coating for the ball and on the other with any inflating thereof. It may even be of advantage in certain cases to allow the inside of the finished ball to be in com munication with the atmosphere through one or more perforations. Under such conditions there is established between the atmosphere and the inside of the ball an equilibrium of pressure and temperature which ensures remarkably constant bouncing properties for the ball.

The ball is provided on its outside with hollowed or relief parts which makes the speed and direction of motion more regular.

The method of manufacture consists primarily in impregnating a fabric with an emulsion or solution of rubber, natural, synthetic or regenerated, completely or partly vulcanized or not vulcanized, and containing in the latter case the reagents required for vulcanization and preservation of the rubber, cutting in this impresnated fabric suitably shaped parts and stamping same to form hemispherical segments after coagulation of the rubber through any suitable means. This stamping has for its effect to drive out part of the coagulation water and the hem-. ispherical segments are thereafter dried and stuck together two by two. The ball is, if desired, covered with a coating constituted by a fabric welded through calendering to non vulcanized rubber and the whole is made fast through vulcanization.

The fabric used may be constituted by vegetable or animal threads or fibres. It will preferably be a balanced fabric, i. e. one in which the composition 1 of the threads and their tension and degree of twisting are the same in the warp and weft, so that the fabric is in equilibrium in all directions. Such fabrics may be .produced by having uniform weft and warp threads subjected to the same tension, or if these conditions are not fulfilled, by superposing two or more layers of a f arbic so placed that any inequalities in the weave balance one another. Such a fabric will absorb rubber in a uniform manner in the warp and weft threads and will have the same elasticityin the-direction of the warp and weft threads respectively.

The impregnation is performed through any known means but inv a manner such as will distribute uniformly and regularly the same weight of emulsion or dissolution over equal surfaces for a given thickness.

, During the deformation due to stamping, part of this water is expelled but a certain amount remains in the fabric and is removed by drying.

During this drying process, there occurs of necessity a deformation of the hemispherical segrnents. For this reason; as the manufacture of tennis balls must be very precise, the drying is performed on a hemispheric support havin exactly the shape and size required for the seg!-' ment. It is of advantage during the drying to hold the edge of the segment on the support, for

V instance by means of a ring .urged downwards.

Preferably I apply then on the seam a band of fabric welded through calendaring to non vulcanized rubber and on each hemispherical segment a circular element of the same fabric also welded through calendering to non vulcanized rubber, so as to form a complete coat round the ball. The whole is then vulcanized inside a'mould which may be smooth or else provided with suitable asperlties so as to give the outer surface of the ball the rugosity required for reducing or increasing its speed in air.

It is of. advantage during this vulcanization inside an autoclave to provide a communication between the inside of the ball and the outside of the mould whereby the pressure of the steam entering the ball ensures a better application of the wall or cover of the ball against the inner wall of the mould together with a much more speedy vulcanization. This also avoids any contact of air with the wall of the ball during vulcanization, air being as well known a detrimental agent for vulcanization.

A considerable advantage of my improved ball consistsin that it is possible to suitably adjust the rigidity of the cover by suitably measuring the proportion of textile material, rubber and charge or vulcanizing elements absorbed, with a view to producing perfectly standardized balls as concerns their initial velocity and height of bounce. It is thus possible for instance to produce a whole series of balls to be used by different players according to their experience and skill.

By way of example it may be stated that for obtaining a hardness comparable to that of the balls used to this day, there may be used a fabric weighing 435 grs. per sq. m. impregnated with a latex bath the concentration of which is 58%, the wringing out'of the water being obtained in a regular manner by a roller weighing 1 kg. travvHIGH-I18.

Fig. 4 is a cross-sectional view or the ball at the moment of the application of the reinforcing belt.

ll'ig. 5 shows. in plan view. a portion of this reinforcing belt. i

Fig. 6 is a plan view of one of the reinforcing circle shaped parts. i

Fig. 7 is a cross-section of. the vulcanizing mould during vulcanization ,Of the ball.

After the fabric has been impregnated throughout with an emulsion or a solution of rubber. natural, synthetic or regenerated, containing the reagents necessary for its vulcanization and preservation, the coagulation is provided by any suitii able means. A circular part I (Fig. l) is then punched out of the material and placed on a stamping machine including a female mould 2 and a' male stamping'part I. The mould I is provided with channels I for removal of the water.

The stamping being performed (Fig. 2) a hemispherical segment 4 is obtainedwith a flange 5. This segment is then transferred on to a drying mould or support I (Fig. 3) the shape and size of which are exactly those desired for the finished segment. Round the mould and over the flange 5 is then arranged a ring I the weight of which is such that it is urged downwards and holds the flange of the segment well applied against the mould. The segment finishes drying on the latter after which the periphery thereof is out to its final shape.

Two finished segments 4 and 4' are then immersed entirely, for instance by suspending them through a suitable hook, in a rubber solution after which they are dried and applied one against the other as shown in Fig. 4. A band of fabric constituted for instance by a ribbon of canvas Hi welded by calendering toa sheet H of non vulcanized rubber is then used. This band has the length required for forming a belt round the ball, the two ends overlapping slightly one another and being out if desired along a bevel so as not to form any supplementary thickness. The band considered is applied over the joint between the two segments 4-4. I then apply over the segments themselves two circular parts I! of the same material as the band ii i. e. formed of canvas or other fabric welded through calendaring to a sheet of non vulcanized rubber. The size of the circular 'parts I! is chosen in a manner such that after application over the hemispherical segments their edges overlap slightly the corresponding edges of the band ll.

The ball thus formed is then carried inside the vulcanizing, mold (Fig. 7). This mould com- ,prises two halves l5--|l connected through a After opening the mould the ball ready for vulcanization.is arranged in the half-mould I 8 and pushed into its housing. its cover being thus transfixed by the needle IS. The mould being then closed, the bolt I8 is drawn in and the mould carried into a steam-heated autoclave for vulcanizing the ball. The vulcanization being performed, the ball is removed and there is introduced inside the opening left by the bushin 2i a stopping part provided with a calibrated hole which allows the reduction to the desired crossa,s7s,eee

parts forming a'complete coating for the ball Y sectional area of the passage allowed for the air through the cover of the ball.

part of the water of coagulation, drying the-hemispherical segments, sticking two of said segments together to form a ball by means of a rubber solution with application of said hemispherical segments one against the other through their peripheries, applying over the joint between said two segments a strip of fabric welded through calendering to non vulcanized rubber, applying over each hemispherical segment a circular part of similar fabric welded through calendering to non vulcanized rubber, said strip and said circular parts forming a complete coating for the ball constituted by the hemispherical segments, and then vuloanizing the whole.

2. A method of making a ball for games, including the steps of impregnating a fabric with an aqueous emulsion of rubber, cutting pieces from said fabric, shaping said pieces into hemispherical segments, after coagulation but while the mass is still wet, in such manner'as to expel a part. of the water of coagulation, drying, the hemispherical segments, sticking two of said segments together to form a ball by means of a rubber solution with application of said hemispherical segments one against the other through their peripheries, applying over the joint between said two segments a strip of fabric welded through calendering to non vulcanized rubber, the ends of said strip overlapping one another applying over each hemispherical segment a circular part of similar fabric welded through calendering tonon vulcanized rubber, said strip and said circular constituted by thehemispherical segments, and then v ulcanizing the whole.

3. A method of making a ball for games, including the steps of impregnating a fabric with an aqueous emulsion of rubber, cutting pieces from said fabric, shaping said pieces into hemispherical segments, after coagulation but while the-mass is still wet, in such manner as to expel a part'of the water of coagulation, fitting each hemispherical segment for drying over a hemispherical mold the diameter of which is that desired for the internal diameter of the finished ball, placing aheavy ring over the periphery of each hemispherical segment to hold it firmly on the mold whiledr drying the segments, re-

moving the heavy ring from the periphery of each segment, removing the dried segments from the molds, sticking two of said segments together by means of a rubber solution to form a ball and then vulcanizing the whole.

I 4. A method of making a ball for games including the steps of superposing a plurality of layers of a fabric, impregnating said fabric layers with an aqueous emulsion of rubber, coagulating said emulsion of rubber in the impregnated fabric layers, cutting suitably shaped patterns out of the fabric layers, stamping the said patterns into hemispherical segments while the mass is stillwet, in such a manner as to expel a part of the water of coagulation, drying the hemispherical segments, sticking two of said segments along their edges by means of a rubber solution to' form a ball, applying over the Joint between said two segments a strip of fabric welded through calenderlng to non-vulcanized rubber, applying over each hemispherical segment a disk of similar fabric welded through calendering to non-:vulcaniz'ed rubber, said strip and said disks forming 40 a complete coating for the ball constituted by the hemispherical segments, and

then vulcanizing the .whole.

LEON MAX SYLVAIN LEJEUNE.

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