Heating platen for a belt press

Claim 1

A press platen for a belt-repair or belt-end-joining press comprising: a four-sided frame formed by a pair of opposite longitudinal edge members, a pair of opposite transverse edge members, and a plurality of equispaced intermediate members extending parallel to said longitudinal edge members, all of said edge members having the same cross section, all of said intermediate members having the same cross section; a heating plate coextensive with the periphery of said frame and secured thereto along a side of said plate adapted to engage material to be pressed; a cover plate coextensive the periphery of said frame and secured thereto along a side of said platen turned away from said material; and a flat electrical heating element lying against said heating plate, said heating element including longitudinal passes extending along said longitudinal and intermediate members with two such passes disposed in each space between intermediate members and between an intermediate member and a longitudinal edge member, bights of said heating element lying along said transverse edge member, said heating plate being formed with transverse heating zones along transverse edges of the platen, longitudinal heating zones along longitudinal edges of the platen, and corner heating zones between each end of a transverse heating zone and an end of a longitudinal heating zone, and a central heating zone surrounded by said corner, longitudinal and transverse heating zones, said central heating zone being formed from a plurality of parallel intermediate heating zones each of which is centered over a respective one of said intermediate members, said frame and said plates having configurations such that the specific material volume is the same in all of said zones, said heating element including bends at said corner heating zones, the specific heat output of said element being uniform over the area of said heating plate.