GB811999A - Mechanically operated press - Google Patents

Abstract

811,999. Toggle presses. LAEIS-WERKE A.G. Aug. 24, 1955 [Sept. 11, 1954], No. 24403/55. Class 87(2). [Also in Group XXII] A toggle press which imparts a preliminary pressure followed by a main pressure has a hydraulic buffer with a valve for limiting the main pressure and, in addition, a valve for limiting the preliminary pressure with means for closing the feed thereto. When the crosshead 13 descends on the pressure stroke the die 14 encounters resistance and a piston-like part 18 extending upwards from it exerts pressure on oil in a chamber 15. A valve cone 20, on the end of a reciprocable shaft, is then open and oil flows past it until the pressure rises high enough to move a valve cone 27, slidable on the shaft, off its seating against a spring 23, whereon the part 18 enters the chamber 15 and forces oil therefrom into a reservoir 30. As the die 14 continues to descend it thus exerts a preliminary pressure until it reaches a point where a limit switch is operated and energises an electromagnet 21 to move a lever 22 to close the valve 20. The hydraulic resistance to the movement of the part 18 is thus increased and the die continues its descent until it exerts the maximum pressure, a limit to which is set by a valve 25 which opens against its spring and allows more oil to flow into the reservoir. When the crosshead rises a spring 16 returns the die 14 and part 18 to their lowest position and oil is therefore drawn from the reservoir, past a valve 26, refilling the chamber 15. The press described is toggle-operated from a motor-driven crank, the end of one toggle link 8 pivoting on a fixed pivot 9 and the end of the toggle link 10 pivoting on a pin 11 passing through the bottom end of a tie rod 12 connected to the crosshead, there being two toggles and two tie rods.