GB411366A - Improvements in and relating to hydraulic presses for impressing stereotype matrices - Google Patents

Abstract

411,366. Hydraulic presses. FOSTER & SONS, Ltd., J., and BRADSHAW, R., Soho Foundry, Preston, Lancashire. Nov. 6, 1933, No. 30797. Addition to 385,158. [Class 69 (ii).] The valve-control mechanism described in the parent Specification is modified by the provision of an electrically-operated cam mechanism linked between the reciprocating- member and the valve-control shaft and acting to control trip mechanism which is continuously actuated by the reciprocating- member and is arranged to engage with or ride over a lever pivoted on the shaft but connected thereto by means of a second lever keyed to the shaft in order to rock the shaft and open or close the valves as in the parent Specification. The reciprocating member 76, Fig. 1, is connected to a lever 10 pivoted on the valve-control shaft 43, and the other arm 11 of the lever carries a pivoted pawl 12 adapted to engage a notch 20, Fig. 3, in an arm 19 on a lever 13 also pivoted on the shaft 43. The pawl 12 can be held out of engagement with the arm 19 by a cam 37, Fig. 6, on a lever 31 pivoted on the shaft 43 and connected by links 35, 36, Fig. 1, to solenoids in the case 87. The lever 31 carries a pin 40 engaging a slot in a lever 42 pivoted, to rock between stops 47, 48, on a stud 45 in the pump well casing and provided with a spring pressed slide 49 having a lateral projection extending under the toe 55 of a starting-lever 54. The lever 54 carries a pawl 30 adapted to engage either of two notches 28, 29, Fig. 4, in a lever 14 keyed to the shaft 43 and formed with two notches 25, 26 engageable by a spring-pressed plunger 24 in the lever 13. When the machine is running idle, the member 76 is reciprocating, and the inlet and outlet valves of the pump are open, the pawl 30 engaging the notch 29. The solenoid controlling the rod 35 is energized, rocking the cam 37 so that the pawl 12 is held out of contact with the notch in the lever 13. The pressure finger of the gauge is at zero, and the indicating- finger is set at the desired pressure. For dry pressing, the plunger 24 is engaged in the notch 25 of the lever 14. The machine is started by depressing the lever 54 to withdraw the pawl 30 from engagement with the lever 14 and allowing the shaft 43 to be rocked by spring pressure to close the valves. When the desired pressure is obtained, the solenoid controlling the link 35 is de-energized, and the solenoid controlling the link 36 is energized, so that the cam 37 is moved out of the path of the pawl 12 which therefore engages the notch in the lever 13 and through the lever 14 rocks the shaft 43 to open all the valves and release the pressure. For hot pressing, the plunger 24 is engaged in the notch 26, so that the notch 20 is given a different setting relative to the pawl 12 to impart only a half of the normal movement to the shaft 43, the pawl 30 engaging the notch 28. This movement of the shaft 43 opens the inlet valve but retains the exhaust valve closed and so maintains the pressure, this being finally exhausted by moving the lever 13 so that the pawl 30 engages the notch 28. If, while the pressure should be maintained constant, a loss of pressure occurs, the solenoid operating the link 35 is energized as a result of the separation of the two pointers on the pressure gauge. The lever 31 is thereby rocked, thus rocking the lever 42 through the pin-and-slot connection and bringing the end of the slide 49 over a pin 15 on the reciprocating lever 10. The slide is raised and its projection engages the toe 55 of the starting-lever 54, causing the disengagement of the pawl 30 from the notch 28 and permitting the shaft 43 to turn to close the valves.