Patent ID: 6250904
Filing Date: 2001-06-26
Classification: B29C,G01P

Abstract:
An extrusion system for extruding a sheet, said system comprising:at least one active extruder roll; andat least one closed loop control system coupled to said active extruder roll and configured to drive said active extruder roll at a substantially constant roll speed;said closed loop control system comprising:a respective roll speed sensor configured to determine an actual speed of said at least one active extruder roll;a respective roll speed controller coupled to said roll speed sensor; anda respective roll drive for receiving a control signal from said roll speed controller, said roll drive coupled to the respective active extruder roll to drive said active extruder roll speed in correspondence with said respective roll speed controller receiving the respective actual active roll speed sensed by said respective roll speed sensor;said speed sensor comprising:a cylinder concentrically coupled to a roll shaft coupled to said active extruder roll;a cam with a linearly increasing radius concentrically coupled to said roll shaft;a first laser configured to project a laser beam to said cylinder; anda second laser configured to project a laser beam to said cam.