GB1394879A - Process and apparatus for moulding an embossed pattern on the peripheral band of a toroidal article in particular on tyre treads - Google Patents

Abstract

1394879 Moulding tyres INDUSTRIE PIRELLI SpA 7 Dec 1972 [17 Dec 1971 20 Oct 1972] 56537/72 Heading B5A In a method of moulding an embossed pattern on the peripheral band of a toroidal article, e.g. on the tread of a tyre, in which the article is pressurized internally by a vulcanizing fluid whilst being vulcanized in a mould, the mould comprises opposed article sidewall moulding sections and a number of radially movable segments which press the peripheral band of the article ; with the mould in the fully closed position one or more of the mould parts are elastically deformed to apply force to the segments thereby counteracting the pressure of the vulcanizing fluid tending to move the segments radially outwardly. The tyre mould of Fig. 1 includes sidewall mould sections 22, 23, radially movable tread segments 20 with inclined surfaces 4 engaged by surfaces of an annular section 3 secured to a frame 5 detachably attached to a plate 10. The section 23 is attached to a cover 12 which, in the mould closed position shown, is locked to an annular housing 8 by a rotatable ring 13 with lugs 14 engaging below lugs 15. In the mould open position, Fig. 2, a tyre and a vulcanizing chamber 51 on a supporting device 49 is lowered into the mould which has its section 22 and segments 20 raised above the frame 5 by rods 26. The cover and section 23 are lowered to contact the tyre and a rod 36 is raised whereupon an annular groove 40 at its upper end is locked to the cover by half-rings 41. The rod 36 is lowered to force the mould assembly downwardly thereby causing the segments to be urged radially inwardly by the section 3. The circumferentially spaced end faces of the adjacent segments are brought into contact and the section 3 is elastically deformed radially outwardly by the time the mould plate 25 contacts the frame 5. Hence a pressure is applied between the contacting end faces of adjacent segments so that the pressure of vulcanizing fluid supplied to the tyre interior does not separate the faces to produce flash. Deformation of the section 3 is adjusted by washers 7a. After disconnecting the rod 36 from the cover the mould may be released from the plate 10 and placed on a further support where it is supplied with vulcanizing fluid at high temperature and pressure via passages 17, 32 and 53. In a modification, instead of supplying vulcanizing fluid to the section 3 and to chambers 31 the mould assembly is located within a housing supplied with such fluid.