| 摘要 |
<p>881,982. Tyre moulds. FIRESTONE TIRE & RUBBER CO. April 5, 1960 [Aug. 13, 1959], No. 11976/60. Class 87(2). [Also in Group XXII] A three-piece mould for a tyre comprises an upper end section 21 and a lower end section 19 having surfaces to mould the beads, sidewalls and shoulders of the tyre and an intermediate section 20 having surfaces to mould the entire axial width of the tread. The tread-moulding section 20 incorporates a thin-walled tread ring 22 which is cast in one piece, forced into true circular form by a expanding chuck and then accurately machined on its outer surface 28, a relatively massive backing ring 23, having an accurately machined bore, being heated and shrunk on to the tread ring. When assembling the mould, the intermediate section 20 may be bolted to either the upper or lower end sections, depending on the type of vulcanizing pressured, a pair of mating, registering surfaces 40, 41 being incorporated so that the sections of the mould are accurately aligned when the mould closes.</p> |
