Apparatus for buffering a variable length loop of strip material

Abstract

A loop buffer having an input and an output deflector roll and a loop roll flexibly mounted between them in a basically vertical position, with its height relative to the deflector rolls determining the loop length of the strip material to be transported. The loop roll is gravity tensioned via a relatively weak spring by a ballast body guided with free movement in a basically vertically direction. The loop roll also includes two or three parallel coaxial loop wheels of slightly different diameter, adapted to the thickness profile of the strip material, transverse to the longitudinal direction. By selecting a relatively weak spring, the loop roll can follow small but quick changes in the transport speed very easily and quickly, with the acceleration forces caused by tile low inert mass of the moving parts remaining very low. Larger drift movements of the loop roll because of speed differences of greater duration between the feeding and removal of the strip material have the effect of displacing the ballast body, the gravity tensioning of the loop roll and thus the tension exerted on the strip material always remaining constant.