Vis-a-vis the slotter head and the same slotter head which

摘要

PROBLEM TO BE SOLVED: To automatically alter the overlap length of a corrugated cardboard sheet by combining the stopper attached to a flap knife and a guide ring having a dovetail groove and the cavity part connected thereto and combining the stopper and a press pin means pressing the same. SOLUTION: A circumferential guide ring 22 having a dovetail groove 21 is attached to a slotter head and a flap knife 3 is fitted in the dovetail groove 21 in a slidable manner. A stepped hole 24 is provided in the flap knife 3 and a stopper 26 is attached to the hole 24 in a slidable manner through a bush 25. A plurality of cavity parts 30 are formed in the shoulder part of the dovetail groove 21 and the hook 29 of the stopper is engaged with the cavity parts 30 with the stopper 26 pushed up by a compression spring 28. By this constitution, the flap knife 3 is prevented from moving on the guide ring 22.