Rotary die cutter

A rotary die cutter comprising:

• a frame provided with a path of sheets to be conveyed;
• a pair of first bearing units arranged at both sides of the path and attached to the frame;
• one roller of a magnet roller and an anvil roller supported by the pair of first bearing units and extending across and perpendicularly to the path;
• a pair of second bearing units arranged above the pair of first bearing units and attached to the frame so as to be moved in a vertical direction;
• the other roller of the magnet roller and the anvil roller supported by the pair of second bearing units and arranged opposite to the one roller, at least one of the magnet and anvil rollers forming large diameter portions at both ends thereof and a small diameter portion at an intermediate portion thereof, the small diameter portion extending between the large diameter portions;
• a pair of support rollers attached to the frame and arranged under and opposite to each end of the one roller so as to support the one roller;
• a pair of press rollers arranged above and opposite to each end of the other roller so as to be moved between a pressing position in which the pairs of press rollers press the both ends of the other roller against the both ends of the one roller and a nonpressing position in which the pairs of press rollers retreat upward from the pressing position;
• a press mechanism attached to the frame so as to support and move the pairs of press rollers between the pressing position and the nonpressing position;
• a roller gap change unit attached to the frame and moving the bearing unit for the other roller between a position in which the both ends of the magnet roller and the both ends of the anvil roller contact with each other and a position in which the both ends of the magnet roller and the both ends of the anvil roller separate from each other so as to switch between two different sizes of gaps between the intermediate portions of the magnet and anvil rollers, two different types of flexible dies whose heights correspond to the two different sizes of the gaps being able to be magnetically mounted on the intermediate portion of the magnet roller;
• a pair of feed rollers arranged upstream of a pair of the magnet and anvil rollers;
• a first drive mechanism rotating the magnet and anvil rollers in such a way that the magnet and anvil rollers are rotated synchronously with each other at an equal circumferential velocity;
• and
• a second drive mechanism rotating the pair of feed rollers,
• wherein a clearance is formed between each pair of the first bearing unit and the second bearing unit vertically opposed to each other when the both ends of the ma net roller and the both ends of the anvil roller contact with each other,
• wherein the roller map change unit comprises:
• a slope formed on at least a part of one or both of the opposed surfaces of each pair of the first bearing unit and the second bearing unit;
• a stopper guided to move between a first position in which the stopper projects into the clearance and a second position in which the stopper retracts from the first position;
• and
• a stopper actuating mechanism attached to the frame so as to move the each of the stoppers,
• wherein each of the stoppers has an inclined surface engageable with the associated slope, and when each of the stoppers is located at the first position, the inclined surface of the stopper engages with the associated slope so that the both ends of the magnet roller and the both ends of the anvil roller separate from each other, and when each of the stoppers is located at the second position, the both ends of the magnet roller and the both ends of the anvil roller contact with each other,
• wherein the roller gap change unit further comprises a position adjusting mechanism provided for each of the stoppers and attached to the frame so as to be adjusted at a position thereof in a direction of linear movement of the associated stopper, and the leading end of stopper contacts with the associated position adjusting mechanism when the stopper is located at the first position,
• wherein a sheet is supplied one by one between the pair of feed rollers, and punched by the flexible die while being conveyed through the gap between the magnet and anvil rollers by the pair of feed rollers.