Constant force roll assembly

摘要

A mounting mechanism for the backup roll of a roll pair wherein a four bar linkage is provided. The backup roll is mounted at one end of a first arm and bears against a mating roll positioned in a stationary location. The first arm extends to a pivot point around which the backup roll rotates to engage the mating roll. A second arm is rigidly connected to the first arm at the pivot point and extends to an end point. A third arm, comprised of a coil spring with a coupler threaded thereto, extends from the end point of the second arm to a stationary point. The fourth arm of the four bar linkage is the ground extending between the stationary points to which the first and third arms are attached. By adjusting the coupler, the number of active coils in the third arm is adjusted thereby adjusting the normal force between rolls to a desired value. By providing the first arm with substantially more length than the second arm, the normal force between rolls is maintained relatively constant over a wide tolerance in the stationary location of the mating roll.