GB581537A - Improvements relating to guards for presses and like machines - Google Patents

Abstract

581,537. Machinery guards. UDAL, J. D., and HERBERT, W. J. Sept. 1, 1944, No. 16706. [Class 80 (iv)] A machine, e.g., a press, is provided with a pivotal guard q which must be closed before the press can be started and which cannot be opened whilst the press is in motion. The power driven flywheel c, Fig. 1, of a machine is clutched to and declutched from the crank-shaft a by a key d; normally urged to the clutched position by a spring and held in the declutched position by the inclined face of an extractor g, pivoted at h, and maintained in its operative position by a spring i. The extractor is controlled by the machine operator through a link p and has in association with it a lever z, secured at one end to a pivotal spindle 2, and carrying at its other end a roller 4 to engage the underside of the extractor. Also secured on the spindle 2 is a lever 5, carrying at its free end a roller 6 adapted to engage a notch y in a disc x mounted on the crankshaft a. The levers z, 5, are held in their operative positions, Fig. 1 by a spring-loaded plunger 7 which acts on the underside of lever z, and which, at its lower end is engaged by a spring-loaded catch 9, connected by a link 10 to the pivotal guard q. To start the machine the extractor is disengaged from the key d by depression of link p by the operator, but, before this can happen, the guard q must be closed in order that the lever z, under the action of the extractor, may displace the plunger 7. At the same time the roller 6 is disengaged from the notch y. The machine performs its operation and the roller 6 then engages the peripheral edge of the disc x i.e., the levers 5 and z cannot be displaced. Also, at the same time, the guard q may not be moved since the lower end of the depressed plunger 7 engages the radial edge of the catch 9. The guard is thus completely locked. Meanwhile, the extractor g has returned to its original position under the action of spring i. Hence at the end of the revolution, the key d again contacts the extractor and thus disconnects the crank-shaft from the flywheel. Levers 5 and z are returned to their original positions by the spring-loaded plunger 7. Fig. 2, shows an alternative construction in which the lever 5 is dispensed with and the lever z carries a roller 6 which coacts with the notched disc x, and at its free end is formed with a cam face adapted to be engaged by an oscillatory spindle 11, controlled by the operator through a link p. In a modification, the catch 9 is replaced by a second plunger disposed at 90 degrees to the plunger 7 and linked to the guard q. In a further modification, Fig. 4, a double armed lever 19, pivoted at 20, bears with one end against the extractor g, and is engaged at the other end by a pivotal catch 22 connected to the guard q by a link 23.