Apparatus for preventing belt distortion

Claim 1

IN A MACHINE FOR FORMING A PRODUCING IN SHEET FORM, FIRST AND SECOND STATIONARY PLATENS HAVING OPPOSED COMPRESSING SURFACES FOR ENGAGING OPPOSITE SURFACES OF THE PRODUCT, FIRST AND SECOND ENDLESS LOOPS OF THIN FLEXIBLE METAL HAVING A HIGH TENSILE STRENGTH AND POSITIONED TO MOVE OVER THE RESPECTIVE SURFACES OF SAID FIRST AND SECOND PLATENS, MEANS FOR DRIVING EACH OF SAID LOOPS OVER THE PLATEN SURFACES SO THAT THE PRODUCT WILL BE DRAWN BETWEEN THE PLATENS BY FRICTIONAL ENGAGEMENT OF THE LOOPS WITH THE SURFACES OF THE PRODUCT, MEANS IN SAID PLATENS FOR HEATING THE PLATENS AND THUS THE PORTIONS OF THE LOOPS BETWEEN THE PLATENS, THE PORTIONS OF SAID LOOPS NOT BETWEEN SAID PLATENS BEING EXPOSED TO CONDITIONS WHICH TEND TO LOWER THE TEMPERATURE THEREOF SO THAT THE PORTIONS OF SAID LOOPS ADVANCING TOWARD SAID PLATENS ARE BELOW THE TEMPERATURE OF THE PORTIONS OF SAID LOOPS BETWEEN SAID PLATENS, AND LOOP PRE-HEAT MEANS IN HEAT TRANSFER RELATIONSHIP WITH SAID LOOPS AT LOCATIONS IN ADVANCE OF SAID PLATENS FOR APPLYING HEAT TO THE LOOPS AT A CONTROLLED TEMPERATURE GRADIENT TO INCREASE THE TEMPERATURE OF THE METAL OF THE LOOPS AT SUCH LOCATIONS TO APPROXIMATE THE TEMPERATURE OF THOSE PORTIONS OF THE LOOPS WHICH ARE BETWEEN THE PLATENS AND THE PRODUCT.