GB424591A - Improvements in presses and pressing mechanism - Google Patents

Abstract

424,591. Presses. MASSEY, Ltd., B. & S., and MASSEY, H. F., Steam Hammer Works, William Street, Openshaw, Manchester. Sept. 1, 1933, No. 24250. [Class 69 (ii)] [See also Group V] A hydraulic or mechanical press has two toggle arms c, d, Fig, 1, having their adjacent ends pivoted to a lever e and their other ends pivoted to a stationary member f and the press ram a respectively ; the free end of the lever e may be raised and lowered by a hydraulic piston, a screw, crank or cam, and the arrangement is such that the first part of the lever movement for the operative stroke brings the toggle arms approximately into line causing a quick movement of the press ram, while the last part causes a slow, powerful movement at practically constant pressure, one toggle arm serving as a fulcrum. Means may be provided for adjusting the maximum pressure, and for holding the ram in its pressing position. In a hydraulically-actuated press, a cylinder n is supplied from a pump r<2> under the control of a valve q<1>, q<2>, shown in full lines in the position for lifting the ram a. When the piston m passes a port s, the pressure supply is byepassed, and the rest of the upstroke is effected by a weight g. When the valve q<1>, q<2> is moved into the dotted line position, the piston m and ram a are moved down, the valve being retained in position by a member u engaging under a collar q<4>, until tripped by a tappet w or pressure-actuated plunger, when a spring v or a weight moves the valve into the upstroke position. A crosshead j moves in a guide k, which in a modification, has its lower portion formed as an arc of a circle, a connecting rod then being employed. The maximum pressure is determined by an adjustable valve x. If desired, one cylinder may actuate two sets of levers e and toggle arms connected to the ram near its opposite ends. In a further form of hydraulic press, the valve q<1>, q<2> is prevented from return to its upstroke position by a member 10, Fig. 10, the piston m being then hydraulically locked in its lowest position, the supply liquid being byepassed through a hole in a piston q<5>, and leakage being compensated by a small pump 11. Alternatively, the ram may be held down by a catch moving in above the crosshead j, and removed when desired by hydraulic means. A multiple camactuated press comprises a rotating body 15, Fig. 11, carrying a number of press units; in each unit, the lever e is connected to a member 26 supported by a pivoted arm 23 and having a spring-pressed roller 25 engaging the edge of a fixed cam 14 shaped to effect the opening and closing operations of the press and hold it closed for a period.