Patent GB-438788-A (GB)
Title: Improvements in or relating to hydraulic presses
IPC: B30B15/16
Filed: 1934-05-23
Abstract: 438,788. Hydraulic presses. AKTIEBOLAGET ALPHA, Sundbyberg, Sweden. May 23, 1934, No. 11682. Convention date, May 23, 1933. [Class 69 (ii)] An automatic hydraulic press has in the conduit for delivering pressure liquid to the working cylinder, a reducing valve so controlled by the movable press table that the pressure of the liquid in the cylinder rises gradually. Clockwork mechanism determines the time between starting and restoring to open position. One form of press embodying the invention is shown in Fig. 1. It comprises a pump 16, accumulators 19, a main ram 8, rams 9 for effecting the approach part of the stroke, draw-back rams 11 and ejectors 52. The cycle of operations is as follows: (1) setting of a clock 25, and actuation of a valve 26 to allow pressure liquid from a main 120 to actuate a servomotor 27. (2) actuation of a valve 24 by the servomotor to allow liquid from the pump to pass to a throttle valve 30 and a valve 32, liquid from the throttle valve passing to the cylinders 2 to raise the table 7, and the main cylinder 1 being filled from a tank 38. (3) the table 7 closes the throttle valve 30, (4) high pressure liquid passes from the valve 32 to the main cylinder 1, (5) return of the clock 25 to its initial position acts through valve 26 and servomotor 27 to set valve 24 so that cylinders 1, 2 are put to exhaust, and table is returned by rams 11 and (6) operation of the ejectors 52. In another form of press, the cylinders 2 are dispensed with, and the valve 24 is modified to allow liquid from a low-pressure pump to pass to the main cylinder 1 for effecting the approach part of the stroke. The indicator disc 402, Fig. 4, of the clock 25 has a fixed hand 404 and an adjustable hand 405, the latter being set to the duration of pressing required. The valve 26 has a spindle 100, normally raised by a spring to its uppermost position, but depressed by a lever 416 acted on a stronger spring 418. Setting is effected by clockwise turning of the disc 402, the hand 405 engaging an abutment 419 and lifting the lever 416 until the abutment is opposite a notch 420 in an unbalanced member 422 ; the member 422 then turns counterclockwise, and the notch encloses the abutment and holds the lever in its uppermost position, until the hand 404 returns to its initial position and acts on the projection 421. When the spindle 100 is in its top position, the valve 26 allows liquid from the pump 16 to pass to a pipe 28 and thence to the throttle valve 30 and valve 32. The throttle valve is a normally open plunger valve adapted to be closed by a lever actuated by a member 198 carried by the table 7, and it comprisess a subsidiary valve which opens at back flow to increase the sectional area of flow. The valve 32 fed with pressure liquid through a pipe 31 comprises a valve 234, Fig. 1, loaded by a spring 237 maintained in compression by an adjustably pivoted lever 242 acted on by a spring 257. When the press table reaches a predetermined height, a rod 273 carried thereby engages a set-screw 271 to lift the lever, relieve the spring 237, and permit the pressure liquid to lift the valve and pass to the cylinder 1 through a pipe 31<a>. The valve group 55 for controlling the supply and exhaust of the ejector cylinders 51 comprises two cut-off valves 294, Fig. 14, each in series with an adjustable needle valve 296 for throttling ; each valve 294 is acted on by a lifting spring 315, and co-operates with a set-screw 342 on a lever 340, the pivot of which is acted on by a spring 323. The ends of the levers 340 have rollers 344 engaging the circumference of a cylinder 355 or discs manually turnable, and provided with opposite flats 359, 360, so that the valves 294 are operated in sequence. The Specification as open to inspection under Sect. 91 comprises a form in which the valve 32 comprises a valve 253 Fig. 10 (Cancelled), normally spring closed. When the press table reaches a predetermined position, a bracket 287 engages set-screws 295 or bolts 297 and raises a collar 289 to compress a spring 290, the inactive turns of which are screwed into an adjustable member 291. The member 291 encounters a member 298 adjustable on a screwed rod 285 and so raises the rod to actuate a lever 282 to operate a plunger 276 to open the valve 253. By means of conical recesses 302 and a claw mounting for the pipe 286, the pipe 286 and collar 289 are turned through 90‹ after each pressing operation. This subject-matter does not appear in the Specification as accepted.