GB1319975A - Vulcanisation method - Google Patents

Abstract

1319975 Retreading tyres W SCHELKMANN 19 June 1970 [9 July 1969 10 Nov 1969] 29913/70 Heading B7C [Also in Division C3] In a method of retreading tyres by vulcanizing pre-vulcanized tread blocks 3 on to a carcass 1, with the interposition of an unvulcanized rubber bonding plate 2, the blocks, plate and carcass are covered with an air tight cover 9 or part cover 10, and introduced into a pressure chamber 20, which is (a) filled with air at 1-2 atm. pressure to remove gaseous constituents trapped under the cover and between the blocks and carcase through passages 13, 14, 6 and holes 19a (Fig. 2, not shown) and out to the atmosphere through a tube 23, and (b) filled with hot water at 5 atm. pressure for intiating the vulcanization. As shown in Fig. 1, the tread blocks 3 have the same curvature as the carcass transversely of the tyre but are not curved in the circumferential direction of the tyre. Air remaining in the interior 29 of the tyre may be evacuated through pipes 27, 28. An heat insulating annular plate 12 is positioned adjacent the edges of the bonding plate 2 to control the flow of heat to the bonding plate 2 and also to assist with the removal of air, from under the cover, by means of channels 31, 32 (Fig. 6, not shown) which communicate with passages 13, 14. If a part cover 10 is used, as in Fig. 4b, this is provided with annular beads 16 under which a further cover 17 may be pushed to ensure that the entire tyre is enclosed.