Mold for forming plastic foam parts

Claim 1

A mold for forming a foam plastic part having a dish-shaped insert embedded therein with the convex face of the insert completely surrounded by the foam plastic comprising, a pair of separable upper and lower mold sections which when closed define a cavity therebetween having a seal around its outer periphery formed by engaged mating edge portions of the two mold sections, said upper mold section having a downwardly facing sealing surface in said cavity located laterally inwardly of said firstmentioned seal, said insert being disposed in said cavity with its concave surface facing upwardly, said insert having its upper outer peripheral edge conforming in contour to and engaging said downwardly facing sealing surface of the upper mold section, the portion of said insert spaced laterally inwardly from said peripheral edge thereof being generally spaced from said upper mold section to form an air space between the insert and the upper mold section except at said peripheral outer edge of the insert, the peripheral outer edge of said insert being spaced laterally inwardly of said seal and the insert also being spaced above the cavity-forming surface of the lower mold section to provide a foam molding chamber which extends around the peripheral edge of the insert and underlies the lower face thereof, a source of vacuum and means forming a communication between said vacuum source and said space between the upper mold section and the insert whereby the lower pressure in said lastmentioned space causes the outer peripheral edge of the insert to forcibly engage and seal with said sealing surface of the upper mold section so that plastic foam molding material can be introduced into said foam molding chamber to completely cover the underside, convex face of the insert.