Variable cutoff printing press with off impression gap
A variable cutoff printing press includes a plate cylinder, a plate cylinder support removably supporting the plate cylinder, a blanket cylinder, a blanket cylinder support removably supporting the blanket, an impression cylinder and an impression cylinder support. An actuator for moving the blanket cylinder support accommodates different blanket cylinder sizes, the actuator further moving the impression cylinder support so that regardless of blanket cylinder size a gap exists between the blanket cylinder support and the impression cylinder support. An on impression actuator moves the impression cylinder support against the blanket cylinder support to set a desired print load. A method is also provided.
1. A variable cutoff printing press comprising:
a plate cylinder;
a plate cylinder support removably supporting the plate cylinder;
a blanket cylinder;
a blanket cylinder support removably supporting the blanket cylinder;
an impression cylinder;
an impression cylinder support;
an actuator for moving the blanket cylinder support about a pivot point to accommodate different blanket cylinder sizes, the actuator further moving the impression cylinder support so that regardless of blanket cylinder size a gap exists between the blanket cylinder support and the impression cylinder support;
an on impression actuator for moving the impression cylinder support against the blanket cylinder support to set a desired print load;
a linkage between the blanket cylinder support and the impression cylinder support, the linkage causing the impression cylinder support to rotate in a same direction as the blanket cylinder support; and
a counterbalance cylinder forcing an end of the impression cylinder support downward.
2. The variable cutoff printing press as recited in claim 1 wherein the counterbalance cylinder is an air cylinder.
3. The variable cutoff printing press as recited in claim 1 wherein the impression cylinder is of fixed size.
4. The variable cutoff printing press as recited in claim 1 wherein the on impression actuator is pneumatic.
5. The variable cutoff printing press as recited in claim 1 wherein the actuator is a motor setting a position of the blanket cylinder support.
6. The variable cutoff printing press as recited in claim 1 wherein the press is a web offset lithographic printing press.
7. The variable cutoff printing press as recited in claim 1 further comprising a frame, the blanket cylinder support being coupled to the frame.
8. A method of operating a variable cutoff printing press including:
setting a first desired blanket cylinder position for a first blanket cylinder using a first actuator, an impression cylinder also being moved by the actuator via a linkage while a gap is maintained between a blanket cylinder support and an impression cylinder support, the first actuator rotating the blanket cylinder support and impression cylinder support in a same direction;
placing the first blanket cylinder, impression cylinder and a first plate cylinder on impression using a further actuator to force the impression cylinder support against the blanket cylinder support;
setting a second desired blanket cylinder position for a different sized second blanket cylinder using the first actuator, the gap being maintained between the blanket cylinder support and the impression cylinder support;
placing the second blanket cylinder the impression cylinder and a second plate cylinder on impression using the further actuator to force the impression cylinder support against the blanket cylinder support; and
applying a counterpressure opposite the linkage pressure to the impression cylinder support.
9. The method as recited in claim 8 wherein the further actuator is pneumatically operated.
10. The method as recited in claim 8 wherein the press is a web offset lithographic printing press.