GB918915A - Sheet gripper mechanism - Google Patents

Abstract

918,915. Printing machines. CRABTREE & SONS Ltd., R. W. May 8, 1959 [May 12, 1958], No. 15226/58. Class 100 (2). A cylinder e.g. the impression cylinder of a printing-machine, comprises mechanism within its diameter for straining an impression blanket about the periphery of the cylinder and a number of grippers to grip a sheet and carry it around with the cylinder as it rotates, the grippers constituting a unit which is detachably secured to the cylinder so that the unit can be removed to expose the straining mechanism without disturbing the setting of the grippers. As shown, the cylinder 1 has recesses 2, 3 accommodating bars 4, 5 to which the ends of the blanket B are secured. The bars 4, 5 are rotatable to strain the blanket and are held in position by pawls and ratchets. The recess 2 is enlarged at 6 to receive the gripper unit which comprises a series of fingers 7 pivotally mounted on a spindle 8 secured to a supporting frame 9. The supporting frame 9 has a number of slots 12 which are engaged by bolts 10 screwing into the body of the cylinder at 11 for securing the frame to the cylinder. The fingers 7 are individually biased into contact with a seat 13 mounted on the frame 9 by springs 14 which react against brackets 14a secured to the spindle 8. Followers 16 are mounted on the rear ends of the fingers 7 and are engaged by tappets 17 for opening and closing the grippers. The tappets 17 are adjustably mounted in arms 18 secured to a spindle 19 which can oscillate in bearings in the recess 6. The spindle 19 is biased in one direction by a spring 19c and is oscillated by means of a cam follower on one end thereof which engages a cam track as the cylinder rotates. The gripper unit may be removed (the full line position, as shown) by slackening the bolts 10 and lifting the frame 9 away from the cylinder. The position of the frame 9 in the recess 6 may be adjusted so as to ensure that the outer face of the seat 13 is level with the outer surface of the blanket B by means of slides 21 which are movable substantially radially in the recess 6 by adjusting studs 22. The slides 21 have bevelled surfaces 20 which engage the inner end of the frame 9 so that movement of the slides 21 before the bolts 10 are tightened results in inward or outward movement of the frame. When the frame and seat 13 have been adjusted the bolts 10 are tightened and the slides 21 are locked by bolts 23 in a bar 24 which is secured to the cylinder and notched at intervals to receive the slides 21.