Patent GB-385158-A (GB)
Title: Improvements in and relating to hydraulic presses for impressing stereotype matrices
IPC: B41D1/00
Filed: 1932-03-24
Abstract: 385,158. Hydraulic presses. FOSTER & SONS, Ltd., J. and BRADSHAW, R., Soho Foundry, Preston. March 24, 1932, No. 8833. [Class 69 (ii).] In a hydraulic press for embossing stereotype matrices, a rapid initial upward movement of the ram 11, Fig. 3, is obtained by admitting fluid to a sleeve 9 secured to the base of the cylinder 6 and extending into a chamber formed in the base of the ram, the movement of the ram towards the end of its stroke uncovering apertures 10 in the sleeve and admitting fluid to the whole of the base of the ram so that heavier pressure is built up gradually. The pump plungers 25, 26, Fig. 5, are reciprocated by eccentrics on a shaft 17 driven from a motor, and the flow of fluid is controlled by valves 34, 35. The valves 34 and the exhaust valve 39 are connected to the inlet and discharge ports 7, 8 of the cylinder 6 and are lifted by levers 36, 42 fixed to a shaft 43. The shaft 43, Fig. 4, is rocked through the medium of a link 45 by a vertically reciprocable carriage 46 and a spring rod 48. The carriage 46 supports a pair of solenoids having a common core bar 52 which is connected to a slide 54 moving in guides 55 on the carriage. The slide carries a bell-crank lever 59 formed with a long and a short arm and adapted to be rocked into desired position by a handle 57. The carriage is guided in its movements on spindles 66, 67 which are engaged by pawls 64 on a shaft 62 carried by the carriage and on which is also mounted the starting-handle 61. A bracket on the back of the carriage supports a rock-shaft 73 carrying rocking levers 74, 75, the former being connected to a crank on a worm wheel 79 driven by a worm on the shaft 17. A pressure gauge 80 is provided in the circuit of the press and is provided with a pressure pointer 81 and a setting-pointer 82 carrying electrical contacts connected to a relay switch which operates the solenoids in the carriage 46, the arrangement being such that the lever 59 is moved out of or into the path of movement of the lever 74, when the pointers are respectively separated or coincident. When not in use, the ram 11 is in its lowest position together with the carriage 46, the spindles 66, 67 being engaged by the pawls 64 and the valves 34, 35, 39 being lifted, so that even though the shaft 17 be rotating, the plungers 25, 26 are running idle. If the press is to be used for dry moulding, in which the pressure is built up to a maximum and then completely released, the lever 59 is turned so that its longer arm is raised into vertical position and the pointer 82 is set at the desired pressure. The handle 61 is then raised to release the pawls 64 from the spindles 66, 67 and allow the carriage 46 to be raised by the spring rod 48, so closing the valves 34, 35, 39 and rendering the pump operative. The cam 11 and table 12 are thus raised, fluid being drawn into the cylinder 5 outside the small cylinder 9 through the port 8 and valve 39 during the first part of the movement. When the desired pressure has been attained and the pointers 81, 82 coincide the solenoid core 52 is reversed to move the lever 59 into the path of movement of the lever 74. The carriage 46 is thus depressed to its lowest position and the valves 34, 35, 39 are opened to exhaust the press. When the pointers 81, 82 separate, the solenoid core 52 is again reversed to set the lever 59 in position for restarting the press. For hot moulding, wherein the pressure is checked at the required height and maintained at that pressure for an unlimited period or exhausted gradually while drying the matrix, the controls are set as for cold moulding, except that the short arm of the lever 59 is turned to vertical position. Consequently, when the maximum pressure is obtained, the carriage 46 is depressed half-way only and the valves 34 are opened to check any further rise of pressure. If the pressure falls, the lever 59 is moved by the core 52 out of the path of movement of the lever 74, and the lever 75 engages a lever 60 to raise the pawls 64 out of engagement with the spindles 66, 67 so that the carriage 46 again rises and renders the pump operative. After a period of maximum pressure, the pressure is reduced by means of a hand-wheel 83 and screwed spindle 84, the pointer 82 reset to the lower pressure required and this pressure maintained until the matrix is dry, when the longer arm of the lever 59 is turned to vertical position to cause the carriage to be fully depressed, the valves 34, 35, 39 lifted, and the pressure completely exhausted.