Shoulder-moulding bag used in tyre prodn. - is produced by building two laminar rubber-bonded bags, assembling them between two drums and curing with compressed air and steam

摘要

A shoulder-moulding bag is produced for the mfr. of tyres. The process uses a first bag made of cords plus rubber and wire cords plus rubber; this is inserted into part of a drum where it will for the shoulder bag; an outer drum is next added and the material of the first bag is bonded to a part of the outer drum. A second bag, with a rubber layer on each side of a fabric core, is inserted into the first drum so as to bond on to the base of a pre-polished valve arm; an end of the second bag is placed on a base surface of the outer drum and a valve connector is assembled with the threaded part of a valve stem. An opposite end of the second bag is folded over to a set line and there fixed by a suitable tool; the second bag is moved so as to press against a particular part of the outer drum and it is there pressed; the material of the first bag is then attached also; the resultant half-finished bag is coated with adhesive and a nylon fabric is applied to it. A covering drum is next applied to the product, and compressed air and steam are fed in at the same time to cure the materials concerned. ADVANTAGE - The process is free from the present problems (e.g. cracks appearing at the most highly stressed areas), esp. the faults in the "C-area", which are liable to occur when the moulding bag is used repeatedly. Moreover the method produces tyres with better properties such as (partic.) service li