Patent ID: 6257862
Filing Date: 2001-07-10
Classification: B29C,B29L,B65H

Abstract:
A plastic sheet extrusion system comprising:(a) a sheet extrusion die,(b) extruder means connected to feed plastic material continuously in a downstream direction to and through said die,(c) a plurality of cooling rolls adjacent said sheet extrusion die and connected to conduct and cool said plastic material from said sheet extrusion die,(d) a roller cooling conveyor having a sheet carrying surface extending downstream of said cooling rolls, said conveyor extending substantially horizontally or inclined to the horizontal a length to cool the sheet,(e) a moveable roller forming said sheet into at least one extendible and contractable accumulator loop also extending substantially horizontally or inclined to the horizontal and positioned adjacent to and beneath said roller conveyor just below said sheet carrying surface,(f) a set of mechanically driven pull rolls downstream of said accumulator loop, and(g) a winder positioned to wind said plastic sheet on a take-up roll,whereby said accumulator loop serves to permit roll change at said winder at reduced speed or zero speed by temporarily accumulating the plastic sheet produced by said sheet extrusion die, and(h) means for increasing the speed of said pull rolls to empty said accumulator loop after said roll change has been completed.