US1593211A

US1593211A - Method of covering tennis balls

Info

Publication number: US1593211A
Application number: US366399A
Authority: US
Inventors: Frank J Faulkner; Charles B Whitney
Original assignee: SPAULDING BROS AG
Current assignee: AG SPAULDING BROS; SPAULDING BROS AG
Priority date: 1920-03-16
Filing date: 1920-03-16
Publication date: 1926-07-20
Anticipated expiration: 1943-07-20

Description

July 20 1926. 1,593,211

F. J. FAULKNER 51' AL METHOD OF COVERING TENNIS BALLS Filed March 16. 1920 3 Sheets-Sha et 1 W 7M ATTORNEYS.

July 20 1926. 1,593,211

F. J. FAULKNER ET AL mz'rnon OF covmune mums BALLS Filed March 1a. 1 2 s sheets s h'ait 2 I I, 1 2 g n 2 ATTORNEYS.

July 20 1926. 1,593,211

F. J. FAULKNER ET AL METHOD OF COVERING TENNIS BALLS Filed March 16. 1920 5 Sheets-Sheet 3 }VE TOR M Mai 1M ATTORNEYS.

Patented July 20, 1926.

UNITED STATES PATENT OFFICE,

FRANK J. FAULKNER, OF LYNN, AND CHARLES B. WHITNEY OF SPRINGFIELD, MAS- SACHUSETTS, ASSIGNORS TO A.

SPAULDING 313.08., OF CKICOPEE, MASSACHU- BETTE, A. CORPORATION OF NEW JERSEY.

METHOD OF COVERING TENNIS BALLS.

Application filed Karel: is, 1920. Serial in. 300,399.

The present invention relates to an improved method of covering tennis balls and the product thereof, and has for its object more particularly, a method of attaching the cover to the rubber-center in a satisfactory manner without the use of stitches at the seams.

A further object of the invention is to apply a fabric cover to a rubber center in a manner to provide an excess of fullness in the fabric so that the cover of the finished ball will have a greater capacity for stretch in unison with the rubber center when the ball is in play. This excess of fullness in the fabric provides for a greater stretch of the fabric than when without fullness and lessens the tendency of the cover to separate at the unstitched seams.

The method heretofore commonly employed for covering tennis balls consists in first preparing the cement coated cover in two pieces shaped somewhat like a figure 8. These pieces are then separately stretched by hand onto the rubber-center in such a, manner that the felt covers will be under tension when in place on the rubbercenter so as to fit smoothly and tightly about the same. Since the rubber-centers are not always of exactly the same size,although the margin of variation is kept within certain narrow limits,the practice has been to cut one semi-cover slightly larger than the other so that the larger overlaps the smaller at the edges. This over-lapping of the edges of the semi-covers in the old process also takes care of any slight lack of symmetry in the disposition of the semi-covers upon the rubber-center, which lack of symmetry in positioning the semi-covers follows necessarily as a result of the manner of stretching the same on the rubber-centers. In finishing the ball under the old process, the over-lapped edge of the larger semicover is then trimmed off with scissors givin to the trimmed ofi edge a more or less bevelled cut. After this trimming operation,- the edges are sewed together by blind stitching for the purpose of preventing the semi-covers from ulling apart or peeling ofi' during the use of the ball in play.

The ob'ectionable features of a tennis ball made an er this former process are that the seams although sewed together as described, do not hold together when subjected to the severe blows of a hard-fought game, the cover soon breaks loose from the rubber center and the edges curl up and peel off. In the former ty e of tennis balls, the sewed seams of blin stitches have not sufficient strength to withstand the tendency of the covers to pull apartrtat the seams. This tendency to pull apart is caused by the fact that every time the ball receives a blow, as from the racket or the ground, it naturally flattens on the contactin surface, causing the rest of the ball to bu ge or stretch out into a distorted shape. It is easy enough for the rubber-center to accommodate itself to this bulging shape because of its inherent elasticity. The felt cover, however, is not sufliciently elastic to yield with the rubber center and moreover such elasticity as the fabric might normally have, has been stretched out of it during its application to the rubber-center under tension, as above described. In other words, the felt cover is stretched practically to its elastic limit on the rubber-center before it receives a blow tending to distort it. Inasmuch as the cover cannot stretch further in following the stretch of the rubber-center, it must necessarily weaken its cemented hold on the rubber-center, creep slightly with res ,ect thereto and pull away at the seams. lhis tendency to pull away at the seams breaks the stitches and the loosening of the cover on the rubber-center soon allows the unsewed edges at the seams to curl and peel off.

The present rocess aims to avoid the objections hereto ore described in connection with the method of making tennis balls as formerly practiced. We have found that by applying the fabric cover to the rubbercenter with an excess amount of fullness in the material or in a manner to compact or compress the fibers and the weave of the fabric together, that there will be imparted to the fabric a capacity to stretch and yield. In other words, instead of taking all the stretch out of the fabric in applying it to the rubber-center, the present recess proposes to increase the capacity of t e fabric to stretch when applied to the rubbercenter, whereby, when the finished ball is subjected to a blow, causin the aforesaid flattening or distortional e ect,the fabric cover will accommodate itself to and follow the rubber-center in assuming the new shape without. loosening its cemented hold upon the rubber-center.

This result is accomplished in a general way by applying the fabric semi-covers, having a cement coated surface as heretofore, loosely to the rubber center taking care to position said semi-covers symmetrically and uniformly on the rubber center but with no attempt to smooth down the fabric on the rubber-center until the symmetrical positioning of the semi-covers in place has been completed. Furthermore, in the resent process, the semi-covers are 0 sufficient area to more than cover the rubber-center, in other words, an over-size fabric cover is applied to the rubber center, so that there is a surplus of material for providing the excess of fullness in the fabric. After the over-size semi-covers have been symmetrically placed in position upon the rubber-center, they are not trimmed to size as was the former practice but are com pacted upon the rubber-center as hereinafter described so .as to compress or pack the surplus of material into a smooth, tightly fitting cover for the ball. This packing and compressing of the surplus fabric into place effects both good adhering contact between the cement coated covers and the rubber-center and also provides for the excess of fullness in the fabric so .that it has a capacity for eater stretch when called upon to do so y the distortion of the ball in play. By excess of fullness in the attached cover, we mean that the fibers and weave of the fabric material are compacted and compressed more closely together so as to have a greater capacity for stretch than when in their normal state. For example, an unstretched or uncompressed fabric may be said to have its normal degree of ful ness, a stretched fabric may be said to have little or no fullness, while a fabric compacted or compressed into a smaller compass, as in the present invention, may be said to have an excess of fullness.

A further advantage of the present process resides in the fact that the semi-covers when over size need not necessarily be cut in the figure 8 shape with concave s1des,but may be cut with straight sides and rounded ends as hereinafter described, thus shortening the necessary length of the semi-covers and also resulting in economy in the cutting of the semi-covers from a strip of felt. The edges of the straight side cover pieces are not adapted for as close fitting abutment as in the contour shaped cover pieces during the preliminary step of wrapping the ball but it is found that the surplus material will be readjusted by the subsequent molding action to finish the ball with the edges closely abutting throughout their length.

. The drawings illustrate different stages in the carrying out of the process and may be briefly described as follows,-

Fig. 1 is a top plan view of the rubber center having, above and below the same, a semi-cover;

Fig. 2 is an elevation of the same parts and showing in dotted lines the semi-covers wrapped about the rubber-center in one of the preliminary stages of the process;

Fig. 3 isa view of the completely wrapped rubber-center and before the ball has been placed in the mold for compressing the cover thereon;

Fig. 4 is a sectional the ball therein; and

ig. 5 is a view of the completed ball;

Fig. 6 is a view similar to Fig. 1 in which a different configuration of semi-cover is employed; and

Fig. 7 is a cross section of the ball showing the over-size cover loosely applied thereto and before being compacted by the molds.

Referring more particularly to the drawings, the present process is preferably carried out as follows:

Semi-covers or cover pieces of fibrous material, preferably felt, such as now employed in covering tennis balls, are preared and cut in the she shown either in ig. 1 or Fig. 6, one 0 said cover pieces being indicated at 2 and the other at 3. The semi-covers are preferably cut to the same area, each one slightly larger than one-half of the surface area of the rubber center 1. The rubber center 1 at present preferred by us for the carrying out of this process is of the fixed standard size heretofore commonly employed for tennis balls-namely, a hollow rubber sphere, preferably vulcanized and inflated, before being covered, to the size and resiliency desired in the finished ball. The invention is not limited, however, to the use of a rubber center vulcanized before being covered, since vulcanization of the center may be completed during the compacting operation of the cover thereon, as hereinafter described. To facilitate the alignment of the semi-covers 2 and 3 in symmetrical position about the rubber-center, markers are provided consisting of interfitting notches and nibs at the ends and sides of said semi-cover as shown, the

view of a mold with notches being indicated at 4 and the nibs,

at 5. These nibs 5 and notches 4 are preferably located at the ends of the longer and shorter axes ofeach semi-cover as shown, although they may be located at other oints if desired so long as they are made or proper interfitting.

- Both the rubber-center andthe semi: covers before bein united are coated with suitable cement suc as air-drying pure rubher cement heretofore common] used in attachin felt covers to tennis b A solution 0% high-grade rubber in naphtha is a typical cement of this character, but the invention is not confined to the use of any particular cement. The semi-covers are positioned at opposite sides of the rubber-center at right angles to one another as shown in Fig. 2, care being taken to see that the symmetrical center of each semi-cover lies in the same axis, indicated at 6, of the rubber center.

The ends of the semi-covers are then wrapped lightly about the sides of the rubber center, the ends of the semi-cover 3 for instance being folded up and the ends of semi-cover 2 being folded down until the nibs 5 of each semi-cover fit into the corresponding notches 4 of the other semi-cover. n this wrappin operation care should be taken to wrap t e ends of each semi-cover about the largest circumference of the ball so as to be symmetrically disposed thereon. This symmetrical disposition of the semicovers will be obtained automatically by bringing the corres nding markers 4 and 5 into register. en symmetrically disposed the normal planes through the longitudinal axes 7 and 8 of each semi-cover will intersect one another at the center of the rubber-center and at right an les. In thus wrapping the semicovers a out the rubber-center, It is desirable to press lightly only the portions of the semi-covers adjacent the markers into contact with the rubber center without folding down the edges of the semi-covers as shown in Fi 2. Little or no pressure need be exerte upon the semi-cover, for at this stage of the process there is no necessity for making a permanent adhesive contact between the semioovers and the rubber center.

After the semi-covers have been wrapped about the rubber center as shown in Fig. 2 the square cut ed s 17 and 18 of the semicovers are then rou ht into abutment as shown in Fig. 3. In this part of the process the cover is not pressed with an in urious pressure into contact with the ru ber center for there is no necessit for attempting to secure any smooth fit 0 the whole cover on the rubber center. At this stage, the ball has the appearance of being covered with an illfittin and over-size cover, lumpy and loosely attac ed. The entire operation of wrapping the semi-covers about the rubber-center and in bringing the edges of the semicovers into abutment is performed in the absence of any distorting pressure upon the rubber center and without stretching the fabric into place as has been the practice heretofore.

The ball is now ready to have the cover compacted and compressed thereon into its smooth tightly fitting shape. This may be accomplished by suitable pressing and ironing devices although we prefer carrying out this partof the process in a heated confining mold under internally-created pressure as will now be described. As shown, a mold is 1provided consisting of upper and lower ha ves 9 and 10, each mold half having a semi-s herical interior molding surface 15, 16. T e mold is heated in any suitable way and for illustration is shown as hollow for the admission of steam at

inlets

11 and 12 and the discharge of steam at outlets 13 and 14. An convenient means (not shown) may be emplbyed to clamp the mold halves together durin the molding operation. The interior mol ing surfaces 15 and 16 are of such size when locked together as not to compress the covered rubber center to a smaller diameter but merely to confine the covered rubber center against the expansion tendency of the heated gas or air within the ball during the molding operation. In other words, the mold has an interior diameter equal (as nearly as it is possible to make it) to the diameter of the standard size rubber center and cover combined and consequently the mold neither permits any substantial expansion of the rubber center nor causes any substantial contraction of the same while the ball is within the mold.

' In molding the cover upon the rubber center the ball is laced within the molds and while the mold; are held tightly together they are heated to raise the temperature of the ball within the mold sufficient to create considerable ressure at the surface of the ball due to the expansion tendency of the heated gas or air within the ball. This molding pressure compresses the loose oversized cover into firm cementin contact with the rubber center, compacts the cover with its su lus material into a smooth snug fit upon t e rubber center and thereby imparts to it the excess of fullness and stretchable character for accommodating itself to the various changes of shape which the ball must undergo in play. The ball is sub 'ected to this internal pressure sufficient y to firmly cement and com ress the cover there on. When a previous y vulcanized rubber center is to be covered, the heat for creating the internal pressure cient to over-cure or substantially change the chemical character of the rubber center and thereby possibly lessen its resiliency and durability. If, however, a partially vulcanized rubber center is to be covered, the heat of the mold may be maintained sufficient to complete the vulcanization of the rubber center simultaneously with the compacting of the oversize cover thereon. An essential feature of the process is to maintain the rubber center at substantially its fixed standard size within the mold and neither contract nor expand the same while should not be suflithe over-size cover is being compacted thereon.

After the ball has been suflicientl heated, cement t e cover to compact and firml thereon, the molds and the ball therein are cooled to normal temperature before opening the mold halves and removing the ball. This may be effected b passing water or cold air through the hol ow interiors of the mold halves at the end of the heating operation. The purpose of cooling the ball before removal from the mold is to restore the normal internal pressure within the rubber center and thus obviate any tendency for the center to expand after its removal from the mold. Since, as before stated, the rubber center is maintained at its standard size while in the heated mold, there will be no tendency for the same to either contact or expand when removed from the mold. After the removal from the mold in the manner described, the ball is finished and ready for play W en cover pieces 2', 3', of the shape shown in Fig. 6, are employed to cover t e ball they are also cut of slightly larger total area than the surface area of the rubber center. The cover pieces are lightly wrapped about the rubber center as heretofore described and the surplus material allows the edges to be abutted although perhaps not as evenly as in the case of the cover pieces shown in Fig.3. It is not necessary however, to bring the abutting edges into touching contact at all points prior to the molding operation. If the edges are brought into opposed relation, the subsequent molding and com acting action of the molds will readjust t e surplus material of the cover pieces so as to finish the ball into substantially the same a pearance as in Fig. 5, and thus bring the e ges of the cover pieces into close abutment. An excess of fullness is also imparted to the fabric by the compactin action of the mold when cover pieces of this she e are employed.

It wi be understood that various minor changes and modifications ma be made in the rocess as above describe without departin from the invention as hereinafter claime What we claim is 1. The procem of covering tennis balls which consists in applyin to a rubber center, an over-size cover 0% fabric and compacting said over-size cover down into a smooth snug fit upon the rubber center.

2. The process of covering tennis balls which consists in a plying to a rubber center, an over-size fabric cover and compacting said cover with its surplus fabric down upon the rubber center into a smooth snug fit, thereby provide an excess of. fullness in the cover giving it a capacity to stretch.

3. The process of covering tennis balls r1c cover and com ing by heat and pressure said cover wit its surplus fabric down upon the rubber center into a smooth snug fit to thereby provide an excess of fullness in the cover giving it a ca acity to stretch.

4. e process of covering tennis balls which consists in applying to a rubber center a multi-piece fabric cover of lar er total area than the surface area of the ru ber cen ter by first abutting the edges of the cover ieces and then compacting the cover with its surplus material down upon the rubber center mto a smooth snug fit.

5. The process of covering tennis balls which consists in applying to a rubber center an over-size cover of fabric and compacting said over-size cover down into a smooth snug fit upon the rubber center b heatin the same within a confining mol 6. T e process of covering tennis balls which consists in applying to a rubber center, an oversize cover of fabric, confining thesame within a mold of sutficient size to confine the ball in its cover without sub stantial pressure before the. ball is heated, and then heating said mold to create an internal pressure within the ball 'for compacting the oversize cover into a smooth, snug fit upon the rubber center.

7. The process of covering tennis balls which consists in applying to a rubber center an over-size cover of fabric and compacting said over-size cover down into a smooth snug fit upon the rubber center by heating the same within a confining mold, and cooling the ball before removin the same from the confinement of said mold.

8. The process of covering tennis balls which consists in wrapping the cover pieces of a multi-piece fabric cover around a rubber center and abuttin the ed es of said cover piece all in the a sence o distorting pressure upon the rubber center, said cover pieces being of larger total area than the surface area of the rubber center and compacting said over-size cover into a smooth snug fit upon the rubber center b heating the same within a confining moldi 9. The process of covering tennis balls which consists in applying to a rubber center of the ultimate size determined upon, an oversize cover of fabric, confining the same within a spherical mold having an internal diameter substantially equal to the diameter of said rubber center and cover combined, and then heating said mold to create internal pressure within said ball for compacting the over-size cover into a smooth, snug fit upon the rubber center.

10. The process of covering tennis balls, which consists in wrapping two semi-cover pieces of fabric in symmetrical position about a rubber center, said cover pieces havwhich consists in applying to a rubber enter, an over-size fa icting substantially straight long sides and curved short sides, and molding said cover pieces into a completely enclosing smooth snug-fitting contact with said rubber center by confining the same within heated molds. 11. A tennis ball comprising, a rubber center and a fabric cover, the fabric of said cover having an excess of fullness therein. 12. A tennis ball comprising, a rubber center and a smooth snug-fitting fabric cover compacted thereon with an excess of fullness in the fabric. 13. A tennis ball comprising, a rubber center and a fabric unstitched cover cemented thereto, the fabric of said cover having an excess of fullness therein.

14. A tennis ball comprising, a rubber center and a fabric cover of surplus material compressed into a smooth snug fit upon said rubber center fullness therein.

15-. A tennis ball comprising a rubber center and having an unstitched fabric cover secured thereto, said cover comprising two pieces of substantially the same shape and area, said semi-covers being of long and narrow contour each provided with markers at the ends of its longer axis arranged to interfit with markers at-the ends of the shorter axis of the other whereby said markers when in interfitting registration in sure the symmetrical osition of said separate cover pieces on said ball.

In testimony whereof we have aflixed our signatures.

FRANK J. CHARLES so as to have an excess of 25 ing substantially straight long sides and curved short sides, and molding said cover pieces into a completely enclosing smooth snug-fitting contact with said rubber center by confining the same Within heated molds.

11. A tennis ball comprising, a rubber center and a fabric cover, the fabric of said cover having an excess of fullness therein.

12. A tennis ball comprising, a rubber center and a smooth snug-fitting fabric cover compacted thereon with an excess of fullness in the fabric.

13. A tennis ball comprising, a rubber center and a fabric unstitched cover cemented thereto, the fabric of said cover having an excess of fullness therein.

14. A tennis ball comprising, a rubber center and a fabric cover of surplus material compressed into a smooth snug fit upon said rubber center so as to have an excess of fullness therein.

15. A tennis ball comprising a rubber center and having an unstitched fabric cover secured thereto, said cover comprising two pieces of substantially the same shape and area, said semi-covers being of long and narrow contour each provided with markers at the ends of its longer axis arranged to interfit with markers at the ends of the shorter axis of the other whereby said markers when in interfitting registration insure the symmetrical position of said separate cover pieces on said ball.

In testimony whereof we have affixed our signatures.

FRANK J. FAULKNER. CHARLES B. WHITNEY.

Certificate of Correction.

- n i i I q i 1 It s hereb certified that the name of the asslgnee 1n Letters Patent No. 1,593.21

grant ed Juli 20, 1926, upon the ap lication of Frank J. Faulkner, of Lynn, and

hitn

Charles B. ey, of Springfield,

assachusetts, for an improvementrin Methods ri Tennis Balls was erroneousl written and printed as A. G. Spauldrng rgip wh reas said nanie should have bin written and pr1nted as A. G. Spaldzrtg cf: Broa. as shown by the records of assignments in this office; and that the said Letters Patent should be read with this correction thereln that the same may conform to the record of the case in the Patent- ()flice.

Signed and sealed this 14th day of September, A. D. 1926.

M. J. MOORE, Acting Gommissioner of Patents.

Certificate of Correction.

It is hereby certified that the name of the assignee in Letters Patent No. 1.593.211. granted Jul 20, 1926. upon the up lication of Frank J. Faulkner, of Lynn. and Charles B. "l'hitney, of Springfield. lilassachnsetts, for an improvement in Methods of Covering Tennis Balls, was erroneously written and printed as A. G. Spaulding Bros, whereas said name should have been written and printed as A. G. Spalding & 31-05., as shown by the records of assignments in this office; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent ()tfice.

Signed and sealed this 14th day of September, A. D. 1926.

[emu] M. J. MOORE,

Acting Commissioner of Patents.