Patent GB-1007686-A (GB)
Title: Improvements in or relating to tennis balls
Inventor: BUKALDERS EDWARDS
IPC: D06C29/00
Filed: 1963-07-08
Abstract: A method of manufacturing a covering fabric for tennis balls comprises knitting a fabric to produce loop formations of pile yarn on one surface securely anchored by means of a ground yarn, changing said pile yarn loops to a close pile of upstanding fibres, and felting the fibres of the pile into a playing surface of entangled fibres.  The knitted fabric may be knitted on a conventional circular knitting machine to form a fabric the foundation of which is a stockinette construction.  The pile loops may be cut by an independently driven disc cutter whilst still held under tension between the cylinder needles and the dial elements of the knitting machine, the cutter working directly underneath the elements in a groove cut in the verge of the dial. The tubular fabric so-formed is cut longitudinally and the edges treated, to prevent unravelling, with a sealing medium which may be a plastics material, applied by passing the fabric edges between a pair of rollers.  The fabric is then fed to a raising machine to change the tufts formed by the cut loops into a close pile.  Alternatively, the knitted fabric is removed from the knitting machine with its loops uncut, slit longitudinally and the cut edges sealed, and then submitted to a raising operation so that the loops are broken and the fibres disentangled to form a close pile.  In either method, the raising operation is performed whilst the fabric is wet or dry.  The pile surface is then submitted to a piling operation to make the fibres more upright. The fabric is then cropped either to cut the pile fibres to a substantially even length or to cut only the upstanding long fibres to form a pile of irregular depth.  Finally, the fabric is milled or fulled to felt down the fibres.  This process may also shrink the fabric dependent on the type of fibres used.  During the manufacture of the fabric it may be scoured, washed or bleached and dried at one or more stages.  In a modification, the fabric is knitted in a flat piece with selvedges.ALSO:A tennis ball covering fabric is manufactured by knitting a fabric to produce loop formations of a pile yarn on one surface securely anchored by means of a ground yarn, changing said pile yarn loops to a close pile of upstanding fibres, and felting the fibres of the pile into a playing surface of entangled fibres. The knitted fabric may be knitted on a conventional circular knitting machine to form a fabric the foundation of which is a stockinette construction.  The pile loops may be cut of by an independently driven disc cutter whilst still held under tension between the cylinder needles and the dial elements of the knitting machine, the cutter working directly underneath the elements in a groove cut in the verge of the dial.  The tubular fabric so-formed is cut longitudinally and the edges treated, to prevent unravelling, with a sealing medium which may be a plastics material, applied by passing the fabric edges between a pair of rollers.  The fabric is then fed to a raising machine to change the tufts formed by the cut loops into a close pile. Alternatively, the knitted fabric is removed from the knitting machine with its loops uncut, slit longitudinally and the cut edges sealed, and then submitted to a raising operation so that the loops are broken and the fibres disentangled to form a close pile.  In either method, the raising operation is performed whilst the fabric is wet or dry.  The pile surface is then submitted to a piling operation to make the fibres more upright.  The fabric is then cropped either to cut the pile fibres to a substantially even length or to cut only the upstanding long fibres to form a pile of irregular depth.  Finally, the fabric is milled or frilled to felt down the fibres.  This process may also shrink the fabric dependent on the type of fibres used.  During the manufacture of the fabric it may be scoured, washed or bleached and dried at one or more stages.  In a modification, the fabric is knitted in a flat piece with selvedges.  The rear face of the fabric is treated with a rubber based or other adhesive solution and the desired shape panels are cut therefrom.  The edges of the panels are then treated with a similar adhesive.  The panels are adhered to the rubber core of a tennis ball and the covered ball submitted to heat and pressure in a mould.