METHOD AND APPARATUS FOR EXTRUSION MOLDING OF SYNTHETIC RESIN SHEET

PURPOSE:To exclude the generation of warpage at the time of secondary processing by controlling the surface temp. of a sheet like synthetic resin on the basis of the temp. difference between both surfaces of the sheet like synthetic resin on the way of cooling before entering a running roll group to suppress the same to a definite value or less. CONSTITUTION:The temp. difference detection means 7 at the intermediate position of a running roll group 4 is constituted of a detector 71 detecting the upper surface temp. of the sheet like synthetic resin, a detector 72 detecting the rear surface temp. of the synthetic resin and a comparator 70 outputting the difference between both detected values of both detectors. A heating control circuit 9 operates the heating control means 83 to a third polishing roll 33 on the basis of the output of the comparator 70 when the temp. detected by the upper detector 71 becomes higher than that detected by the lower detector 72 to enhance the rear surface temp. of the sheet like synthetic resin and operates the heating control means 82 to a second polishing roll 32 when the temp. of the lower detector 72 becomes higher.