GB930364A - Means for increasing the drive power of a piston and for controlling the return thereof - Google Patents

Abstract

930,364. Stapling machines. SENCO PRODUCTS Inc. April 11, 1962 [Feb. 14, 1962], No. 14000/62. Class 89 (3). A pneumatic stapling machine comprises a piston 28 movable in a cylinder 21, during a working stroke, from an initial position to a final position, by compressed air controlled by a valve 45, a reservoir 50 to receive pressurized air in order to effect the return of the piston to its initial position after the pressure of the driving air has been reduced, a port 52 which introduces compressed air into the reservoir only after the piston has completed its working stroke, ports 51 for communicating the reservoir with the cylinder in order to return the piston, and passage means 55 to exhaust the air moved by the piston during its working stroke from the machine. The compressed air is fed via a port 27 into a chamber 26, which, when a trigger-operated valve 40 is actuated, communicates, via the valve 45, with the cylinder 21. The air then acts on the piston. 28 and forces it downwardly, the air in front of it being exhausted through the passages 55 formed in a resilient stop 33, and the passage 24 formed in a guide 22 for the staple driver 29. The exhaust is prevented from entering the reservoir during the downward stroke by means of an 0- ring 57 which is urged into contact with a seat 56 formed in the cylinder 21, by air passing through the ports 51. When the piston reaches the resilient stop 33, the driving air enters the reservoir via the port 52 which is controlled by a valve 53 loaded by a spring 54. Upon release of the valve 40 to cut off the supply of air to the cylinder, the pressure built up in the reservoir returns the piston to its initial position where it is retained by means of a magnet 36. In the modification shown in Figs. 7 and 7a, compressed air fed into a chamber 63 in the machine, normally maintains a spring-loaded valve 66 in a closed position. Upon operating a trigger 39, a valve 80 is actuated which cuts off the supply of air to the top of the valve 66 which then opens and permits air to act on the piston 28. The air in front of the piston during the working stroke is exhausted via passages 51, 75, a valve 70 and ports 76, the valve having been moved by the compressed air to a position wherein the exhaust air is prevented from entering the reservoir 50. On completion of the working stroke, compressed air is fed into the reservoir via the ports 53. Upon release of the valve 80, the valve 66 closes, thus cutting off the supply of air to the top of the piston and to the valve 70. The air in the reservoir then acts on the piston via an annular recess 72 in the valve 70, and a port 75, 51 to return the piston to its initial position where'it is retained by a magnet 36a. Specifications 779,042 and 894,840 are referred to.