GB1498892A - Racket manufacture - Google Patents

Abstract

1498892 Glass fibre racket STARWIN INDUSTRIES INC 30 Jan 1975 [30 Jan 1974 18 June 1974] 4183/75 Heading A6D [Also in Division B5] A racket frame is manufactured from a tubular member which is formed by winding a plurality of layers of high tensile strength binder impregnated fibres, about a mandrel, the tubular member being formed into a racket shape in a mould and the binder cured in a further mould. The mandrel comprises an elastomeric (preferably rubber) tube 30, (Fig. 2) core wires 31 and 32 and a filler member 33 on a carrier wire 34. The mandrel is mounted in a tensioning and winding apparatus (Fig. 2) for rotation by a motor 40. The mandrel is rotated and layers of binder-impregnated fibre are successively applied to it to form a tubular member 20. At least one layer has its fibres running lengthwise of the mandrel whilst there are at least three other layers which are helically wound each of unidirectional hand with successive such layers being of opposite hand. The mandrel and tubular member are removed from the winding and tensioning apparatus and the core wires 31 and 32, filler member 33 and wire 34 are removed from the tube 30. The tubular member 20 and tube 30 are formed into a racket shape in a mould 60 (Fig. 5) together with a spreader member 26 and filler piece 25 and then refrigerated. The racket frame-shaped tubular member 20, tube 30 and components 25 and 26 are then placed in a mould (Fig. 6) comprising three parts, 70, 71 and 72, together with crescent shaped strips 80, layers 81, strips 82, pieces 83 and a strip 84, all of resin-impregnated fibres. The mould parts 70 to 72 are closed and maintained at the desired curing temperature for the resin and when the tubular member 20 warms up from its previously refrigerated state and softens, the tube 30 is inflated to press the walls of the tubular member 20 against the surfaces of the mould. After an initial cure process the racket frame so formed may be removed from the mould, the tube 30 removed and any surplus material removed from the frame prior to a final cure process. During the moulding and initial cure process, a rib 77 in the mould part 72 forms a groove (for receiving loop portions of racket strings) in the tubular member 20 along a portion where said tubular member has an increased cross section perimeter due to the presence of the filler member 33 on the mandrel during the formation of the tubular member. The moulding process may be modified (Figs. 19 to 21 not shown) to produce holes in the tubular racket frame for racket strings to pass through or alternatively said holes may be drilled in the cured racket frame after moulding. Modifications to the throat and handle portions are described (Figs. 15 to 18 not shown). Filler pieces used in the throats may be of balsa wood, resin impregnated fibres or plastics foam.