GB1377495A - Pneumatically controlled machine - Google Patents

Abstract

1377495 Machinery guards SOUTH WALES SWITCHGEAR Ltd and L N JONES 12 April 1972 [19 April 1971] 9793/71 Heading F2J In an hydraulic press brake having a main beam A, a V-block B and a safety guard C controlled by an hydraulic circuit, the arrangement is such that the main beam A cannot move into its working position until the guard C moves into its guarding position, and movement of the guard C into its guarding position actuates pneumatic means for controlling the movement of the main beam A into its working position. On depression of a pedal I, a poppet valve 1 is opened to supply an impulse of air through pipe 14, valve 4, and auto-change valve 5 to vent a pipe 95 and a cylinder 9 to atmosphere so that the guard C may fall under gravity to its safety position. The consequent movement of a guard operating lever E causes operation of a valve 10 which initiates the supply of air to the cylinder 9 to maintain the guard C in the safety position, and also causes operation of a poppet valve 8 which initiates descent of the beam A. As the beam A descends, a cam H actuates valves 7 which supply air to change the conditions of valves 5, 6 and cause air to be supplied to the right-hand side of the piston in cylinder 9 and hence cause the guard to rise, enabling the machine operator to see the workpiece more easily. The beam A can then be allowed to move upwardly by allowing the pedal I to return to its original position.