Importance

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Abstract

A perforator has a rotary drum. A plurality of die sets are arranged at regular intervals around a peripheral surface of the drum and circulates along with the peripheral surface. Each of the die sets has a pair of die and punch. The die is secured to a die holder which is mounted to the peripheral surface, and the punch is secured to a punch holder which is linearly movable in a direction perpendicular to the peripheral surface between a punch position where the punch is fitted in the die and a retracted position where the punch is retracted away from the die. The sheet material is brought into contact with the peripheral surface within a predetermined range, and conveyed on the peripheral surface in the same direction at the same speed as the die sets. An annular punch drive cam disposed surrounding the peripheral surface drives the punch holder to move between the punch position and the retracted position. The punch or the sheet material is shifted into a relief position where the punch cannot interfere with the sheet material beyond the predetermined contact range of the sheet material with the peripheral surface.

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First Claim