GB955562A - Improvements in or relating to guards for machines - Google Patents

Abstract

955,562. Machinery guards. J. E. THOMPSON. Jan. 4, 1963 [Oct. 4, 1961], No. 35800/61. Heading F2J. In a guard arrangement for an index cutting machine described in Specification 955,561, a guard 86 first performs a movement into the safety position, in order to determine that position, and subsequently detects the presence of a foreign body at any position of travel of the guard member into the safety position, and switch means associated with the guard are arranged to initiate the operation of the machine after a, guard setting cycle and when the guard reaches the safety position without having encountered any foreign body. The guard 86 is guided by rearwardly extending arms 91 and is carried by links 89 from arms 87 secured to a shaft 83 which is adapted to be rotated, in order to lift or lower the guard, by means of a lever 85 actuated by a piston rod of a compressed air cylinder 84. A switch arm 96 is rotatably mounted on the shaft 83 between fibre discs 94 arranged between plates 95 secured to the shaft. On actuation of a foot switch 75, the switch arm 96 is moved upwardly, by a ram head 100, to actuate an arm 101 of a switch 102, against the frictional resistance of the discs 94. The main foot switch 76 is then depressed causing actuation of the guard cylinder 84 to effect lowering of the guard to touch the papers or book to be cut. As the guard descends, friction slipping occurs between arm 96 and the discs 94, thus effectively setting the guard height in relation to the rotary position of the arm 96 on the shaft 83. Release of the main foot switch 76 causes the guard to be raised and a second depression of the switch 76 causes the guard to be lowered again, the arm 96 actuating the arm 101 of switch 102 thereby initiating the operation of the machine.