Mold for manufacturing an annular object of elastic material

Claim 1

A mold having a cavity for manufacturing an annular object of elastic material with an annular reinforcing element embedded therein, wherein the reinforcing element is positioned in the cavity before the elastic material is injected into the cavity, comprising: a plurality of pins supported by the mold and projecting into the cavity; a support surface on each pin extending in a common plane for supporting the reinforcing element in position in the cavity; a guiding surface on each pin extending in a common truncated conical surface intersecting said common plane, the diameter of said truncated conical surface decreasing in the direction away from said common plane of said support surfaces and being substantially equal to the inner diameter of the reinforcing element at a plane passing through said truncated conical surface and extending in parallel adjacent spaced relationship with respect to said common plane of said support surfaces, so that said guiding surfaces guide the reinforcing element into correct position and retain the reinforcing element in correct position on said support surfaces when introduced into the mold; and a sprue for injection of elastic material extending through said mold and communicating with said cavity at a position substantially opposite to the plane of said supporting surfaces so that material injected through said sprue will act on the reinforcing element to retain it against said support and guiding surfaces.