Patent ID: 7594460

Claim:
A method of separating long lengths of unwound item(s) selected from the group consisting of fibers, fiber strands, string, yarn, wire, tape and ribbon into short pieces comprising pulling one or more items in an unwound form into a chopper comprising a frame, a rotatable backup roll outboard of one side of the frame, the backup roll having a peripheral elastomeric working layer, a rotatable blade roll outboard of the side of the frame, the blade roll having a plurality of blades spaced apart around its periphery for contact with and penetration of said items and into the peripheral working layer of the backup roll and a biasing system for biasing the blades of the blade roll and the backup roll together to form a nip between the blades and the elastomeric working layer of the backup roll and operating the chopper comprising rotating the backup roll to pull the items into the chopper at a speed exceeding 2000 feet per minute; the improvement comprising using as a biasing system an assembly for biasing the blade roll and the backup roll together the desired amount, said assembly comprising a mechanical jack that extends and retracts as an element of the mechanical jack is rotated in one direction to bias the blades of the blade roll against the backup roll and in the opposite direction respectively to back the blades away from the blade roll, a motor and a programmable controller for the motor for rotating the mechanical jack to move the blades into a working layer of the backup roll a desired amount, measuring the diameter of a new or reconditioned backup roll being placed on, or already on, the chopper and inputting that diameter information into the programmable controller, the programmable controller and the motor also instantaneously allowing a thicker portion of the items to pass through through the nip while allowing the chopper to resume normal chopping quickly without shutting down and without causing the blades to penetrate excessively into the peripheral working layer.