GB434949A - Improvements in the manufacture of hollow rubber articles - Google Patents

Abstract

434,949. Moulding hollow rubber articles such as balls &c. TALALAY, J. A., 5, St. Minver Road, Bedford. Jan. 10, 1934, No. 931. [Class 87 (ii)] In moulding hollow rubber articles having walls of uniform thickness, such as balls, bulbs or dolls, from sheets of unvulcanized stock in moulds having cavities, a stock sheet 9 of non- uniform thickness is used, the parts 15 of the sheet corresponding to the cavities 2 in the mould being of greater thickness than the parts corresponding to raised portions of the mould, the thickness varying with the varying depth of the cavity. The mould may be in two parts 1<a>, 1<b> hinged together and each cavity may correspond to the shape of one half of the article. For making balls the thickened parts 15 may be plano-convex or bi-convex. The cavities 2 are connected by ducts 6, 3, 4 to a cock connecting to a vacuum pump or vessel and a compressed air conduit. Channels 7 surrounding the cavities are connected by bores 8 to the cock or to another pressure and suction system. The sheets 9 may be formed between engraved rolls or plates or by gelatinating latex on such plates and may be built up from layers. Sheets 9 are laid on each mould part and the channels 7 and ducts 6 are connected to suction to draw and hold the sheet first at the channels 7 and then draw the parts 15 into the cavities where they are stretched to uniform thickness. An inflation block and blowing material are placed in the ball halves, their edges are coated with rubber cement and the mould is closed, waste stock being cut off in the channels 7. Air is admitted to the ducts to blow out the waste stock and the articles are transferred to a vulcanizing mould. Suction and pressure or suction or pressure may be used with or without cores.