Method of and apparatus for trimming lateral marginal portions of sheets in a stream of partly overlapping sheets

摘要

Apparatus for trimming lateral marginal portions of a scalloped stream of partially overlapping sheets has two counterknives at that side of the path for the sheets which is adjacent the leaders of successive sheets and a pair of rotary knives located opposite the counterknives at the side of the path which is adjacent the trailing ends of successive sheets. The sheets of the stream of sheets issuing from a printing machine must be inverted by 180 DEG if the counterknives are located beneath the respective rotary knives. Trimming operations which are carried out upon successive sheets having leaders at that side of the path which is adjacent the counterknives are less likely to result in tearing of the sheets than the trimming operations in conventional apparatus. The blades of rotary knives are normally rotated to advance their cutting edges in the direction of transport of the scalloped stream while the cutting edges of the blades cooperate with the cutting edges of the respective counterknives to remove the surplus of sheet material at the lateral marginal portions of the moving sheets.