GB570275A - Improvements in guards for machines - Google Patents

Abstract

570,275. Machinery guards. MERRIS, T. Aug. 31, 1943, No. 14187. [Class 80 (iv)] Consists in a guard for machines such as crank-shaft operated presses. The guard is locked in its safety position during the working stroke, and is also interlocked with the clutchengaging gear. The crank-shaft 11 is mounted in the machine frame 10. The side members 14 which carry the guard are mounted on a shaft 13 supported by brackets 12, and carry also a rockable shaft 15 on which is mounted the main guard comprising arms 18 between which is a grid. A sliding guard 22 has a cross-bar 24 and side members 23 which are connected to arms 20 on shaft 15 by links 21 the pivot pin 27 of which and the bar 24 slide in slots 17 in the members 14. A collar 29 on shaft 15 has a shoulder 30 adapted to be engaged by a detent - 32 connected by a link 33 to a spring-loaded operating lever 34. A lever 39 on shaft 15 has a slot 40 to receive a pin 41 on a link 42 pivoted at 43 to an arm 44 of a bell-crank lever the other arm 44a of which is connected to a slide 47 guided at 48 and 49, 50 and carrying a roller 55 which engages a cam groove 52 in a disc 51 on the crank-shaft. One half of the cam groove is concentric with the pin 50. The roller 55 is in a radial portion 54 of the groove when the guard 18 is in open position and therefore the crankshaft is locked, but when detent 32 is released and the guard closed, the shaft 15 is turned and the roller 55 brought into the concentric cam part 52 thus permitting the crank-shaft to rotate, and during this rotation the guards are locked in their closed position. A spring 56 may assist movement of the guards from open to closed position. After half a revolution, the cam groove 53 moves the slide 47 and thereby the guard 18 to a position slightly beyond that shown in Fig. 2, to enable the detent 32 to fall under the shoulder 30 when the weight of the guard brings the roller 55 into the radial part 54. The clutch is actuated by a pedal lever 58, Fig. 4, connected by a link 61 to the clutch mechanism. The link 61 is connected by a link 64 to an arm 62, loosely mounted on the shaft 13, and connected by a slotted link 67 to a pin 68 on the guard 18. Thus when guard 18 is open, the clutch cannot be engaged. A further lock is provided by a slot 71 in the boss of arm 62 being engaged by a pin 72 loaded by spring 73 and connected by a link 76 to a lever 78 adapted to be moved by a cam 80 on shaft 15 when guard 18 is moved to closed position to withdraw the pin from the slot and permit the arm 62 to be rotated. In operation, the guards 18, 22 are moved to their closed position by actuating the lever 34 to disengage the detent 32. The guard 18 then moves by its own weight, assisted by spring 56, the shaft 15 is rotated and the roller 55 brought into the part 52 of the cam. A torsion spring 81 acting through arm 82 and pin 83 holds the members 14 against the machine table.