GB875445A - Method of making a resilient diaphragm and diaphragms produced thereby - Google Patents

Abstract

875,445. Laminates. DUNLOP RUBBER CO. Ltd. Feb. 21, 1958 [March 2, 1957; July 25, 1957], Nos. 7009/57 and 23554/57. Class 140. [Also in Groups V and XXVI] A method of making a resilient annular diaphragm 1, Fig. 1, suitable for fluid-pressure springs comprises wrapping at least two sheets 9, 11, Fig. 4, of rubberized parallel-corded fabric around a mandrel 8 so that the cords in the separate sheets cross over to form a lattice and lie at opposed angles to the axis of the mandrel, the substantially cylindrical body 14 thus formed being inflated, shaped and finally cured. To form the diaphragm as shown in Fig. 1, a thin uncured rubber sheet 7, Fig. 4, is first wrapped around the mandrel 8 and, over this sheet is laid the corded-fabric sheet 9 which has been cut on the bias so that its cords, which may be of rayon, nylon, cotton or wire, lie at a small bias angle with the mandrel axis. A second corded-fabric sheet 10 with its cords parallel with the axis may then be laid-over the sheet 9 before the third sheet 11 is assembled, the latter sheet being finally covered with a thin sheet 12 of uncured rubber. After removal of the completed cylinder 14 from the mandrel, one of its ends is plugged and pressurized air is admitted through the other end to expand the cylinder into a spherical-shaped body and thereby stretch the sheets 9, 10, 11 so that the cords 2, 6, 3 become curved as shown in Fig. 3. The body may then be cut into two cup-like members, the peripheral edges 18, 19, reinforced as at 20, and the member placed in a mould of the desired final shape and cured to form the diaphragm 1. A double-walled diaphragm may be formed by folding the spherical-shaped body back on itself with, if desired, a reinforcement 20 in the fold and another adjacent the other peripheral edge of the diaphragm and, when cured in the mould, the two walls become integrally united. Before the expanding operation, one or more constriction bands may be located around the cylindrical body so that, after inflation, a corrugated shape is formed. The layers 9, 10, 11, Fig. 4, may be arranged in any desired sequence on the mandrel and, if desired, the layer 10 may be omitted. The first Provisional Specification describes also the formation of a diaphragm by stretching the built-up layers of uncured rubber and cord fabric on a mandrel from one or both ends and using one or more layers of cord fabric to form the structure.