Opposed arm web accumulator

Abstract

In one embodiment of a web accumulator, at least one pneumatic cylinder actuator has a chain loop connected to opposite ends of its piston rod. Translation of the chain in response to pressurizing the cylinder causes the chain to drive two spaced apart axle shafts in the same rotational direction. An arm is fastened to each axle shaft and there is a row of rollers on each arm and a roller on each axle shaft. Web is threaded in loops back and forth between rollers on the respective arms. When the web infeed rate to the accumulator and the outfeed or rate at which the web is drawn out by a web consuming device are equal, the regulated air pressure to the actuator drives the arms apart to thereby accumulate a long length of web. When web infeed is interrupted while outfeed or draw persists, the arms are pulled toward each other and they pay out the stored length of web. In one embodiment, web tension may vary with the angles of the arms on each side of an imaginary center line to which the axes of the axle shafts are perpendicular. Compensation for such variance may be made by varying the air pressure is accordance with such angle. In the other embodiment, the chain drives the axle shafts through a lever whose radius varies along its profile, providing constant tension throughout the range of angular motion.