GB959270A - Air-operated guillotine - Google Patents

Abstract

959,270. Shearing. E. G. TELFER. April 16, 1963 [April 13, 1962], No. 14839/63. Heading B3W. A pneumatically operated guillotine in which the moving blade is secured to a frame pivoted on the main frame of the machine has a main air cylinder connecting the blade frame to the main frame, a servo-valve connected to the main air cylinder, an air clamp, and a two-stage pilot valve, the first stage operating the air clamp and the second stage operating the servovalve. The main frame comprises two end plates 11 connected by a front plate which carries the fixed blade 15. The moving blade 23 is mounted on a frame 20 supported in adjustable eccentric bearings 17 on the end plates, and connected by links 26 to crank arms 27 mounted on a rocker shaft 28. The rear edges of the end plates are connected by a pipe 32 which has four pairs of lugs 33, each pair supporting the trunnion of an air cylinder 34. The piston-rod of each cylinder is connected to the second arm 36 of the cranks 27. Each pair of lever arms 36 is connected by a plate which carries a rubber buffer 39 adapted to strike the rear face of the plate 12, whereby the energy released at the final stages of a cut is absorbed. The links 26 have lugs 44 which carry the lower end of heavy return springs 45, the upper ends of which are anchored on the end plates at 46. A treadle 51 operates a pilot air valve 55 which when moved to a first stage position admits air to a hose type clamp 63 and when moved to a second stage position also admits air to a selector valve 82. The selector valve 82 is manually operated and is moved to a position in which it admits air to two, three or four main air cylinders according to the thickness of material to be cut. Air passes through the selector valve 82 to the top of the spool type servo-valves 67 mounted one on each main cylinder and forces the spool 69 down against a spring 75 so that air passes from an inlet 71 to the cylinder 34. When the pilot valve is reversed, the spool 69 is returned by the spring 75 and the cylinder exhausts through a port 73. When the treadle 51 is operated to move the pilot valve to its first stage position, an arm 91 is raised so that a cam 92 on the main rocker shaft can move under a roller 93 and prevent return of the treadle. This ensures that the clamp is operative during a cutting operation. To operate the clamp only the treadle is depressed to the first stage position of the pilot valve and is locked in that position by a hook 97 operated by arm 95.