GB602045A - Improvements in or relating to a gripper mechanism - Google Patents

Abstract

602,045. Gripper mechanism. HARRISSEYBOLD CO. Oct. 12, 1945, No. 26670. Convention date, June 24, 1942. [Classes 100(i) and 100(ii)] Sheets are held to the impression cylinder 12 of a rotary offset printing-machine, or to other sheet-carriers by means of grippers 28 mounted on a shaft 23 which is operated by a pin-and-slot connection between the gripper crank-arm 25 and a lever arm 31 pivoted to the carrier and adapted to be oscillated by a roller 40 which engages a fixed cam 41, the lever 31 being acted upon by a compression spring 38 tending to move it clockwise about its pivot 33 to the position shown in Fig. 4 in which the grippers are closed. In this position the slot 27 extends in a line directed towards the shaft 23 of the grippers, and at an angle greater than 45 degrees to the line of centres of the pivot pin 30 and the lever pivot 33. The leverage through which the spring 38 acts varies as the cylinder 12 rotates and is at a maximum when the grippers are closed, thus compensating for diminution of spring power as the spring 38 expands. A stop 46 limits the closing motion of the gripper shaft 23. The cam 41 is shaped so as to permit the grippers to remain closed until they reach the position X when the grippers are opened slightly to permit transfer of the sheet to the grippers of a delivery mechanism and then before the sheet-receiving position is reached the grippers are tumbled over to open position and are received in a recess 22 in the cylinder 12. The slot 27 may be radial, or may be cam-shaped or one side of the cam slot may be dispensed with and the pin pressed by a spring into contact with the plain cam. The lever 31 is curved to clear the shaft 21.