IMPROVED SYSTEM AND METHOD FOR CONTROLLING THE SPEED AND TENSION OF AN UNWINDING RUNNING WEB

摘要

A system and method for controlling the speed and tension of a web being unwound from a rotating roll (12) and being run through an inertia-compensated festoon (32) and then to a web-using production process (42) which requires the web to run at a preselected relatively high speed and a preselected relatively low tension. Based on sensing the amount of web stored in the festoon, a brake (16) applies a decreasing braking-force to the running roll as the diameter of the roll decreases. Wen the roll has decreased to an intermediate diameter, where the decreasing tension torque is inadequate to continue to accelerate the roll, a motor (18) engages the roll and increasingly adds assisting web-unwinding torque to the roll as the diameter of the roll continues to decrease. The brake (16) is also used to stop the roll before a subsequent zero-speed web-splice.