Prodn. of smooth bead area on tyres - where small plastic or rubber ring is inserted in mould to form smooth transition area between bead-forming part and bag press

摘要

A tyre is produced in which the beads are on the radially inner circumference of the rim. When the raw tyre is being cured the bead and lower sidewall are moulded smooth by means of metal rings and the rest of the tyre is pressurised internally with a heated bag press. The transition area between the bead-forming ring and the bag is formed by a plastic or rubber ring. The figure shows the female mould segments (1,2) and blocks (3). To make the surfaces of the tyre smooth where they must be sealed against the rim the set-up has two bead-shaped rings (5) which can be moved radially. The rest of the structure is conventionally moulded by the heated bag method so that the raw tyre is pressed against the tools (2,3). Both the bead-shaping rings (5) are extended by plastic or rubber profile rings (7), each of which fits into its recess on the block ring (5) so as to present one flush face for application by the bag (10). The ring (7) is aligned obliquely so that the bag (10) meets its tip at the sidewall at an angle of less than 10 deg.. ADVANTAGE - The procedure eliminates the current problems of slight displacements in the transition area concerned (which arise from the differential pressure applicable and which cause internal material to stand out).