Molding apparatus for making toroidal manufactured articles from closed-cell, low-density, expanded elastomeric material

摘要

A toroidal semifinished product (5) made of raw elastomeric material is semivulcanized in a semivulcanization chamber (4) defined between two half-molds (2, 3) disposed close to each other. A pressure, preferably equal to the pressure exerted by the gases generated in the semifinished product (5), is created in the mold (1a). The half-molds (2, 3) are moved apart from each other and pressure in the mold is gradually reduced, thereby giving rise to the expansion and consequent transferring of the semifinished product (5) from the semivulcanization chamber (4) to a surrounding final vulcanization chamber (6). When the inner diameter of the semifinished product (5) is larger than the inner diameter of the final vulcanization chamber (6), said chamber is closed at its inner circumferential edge and then, after possible pressure increase in the mold, at its outer circumferential edge, in order to integrally enclose the semifinished product and enable completion of the vulcanization process.