GB895434A - Improvements in hydraulic forging presses having control means - Google Patents

Abstract

895,434. Hydraulic forging-presses. SCHLOEMANN A.G. Nov. 24, 1959 [Nov. 25, 1958], No. 39794/59. Class 83 (4). [Also in Group XXIX] In an hydraulic forging press, particularly for rapid forging, fed with low-pressure liquid from a storage vessel 18 for pre-filling and with highpressure liquid from an accumulator 5 for pressing and withdrawing, through a main valve control device 11 actuated by a cam shaft 21, the latter is driven by a continuously running variable-speed motor 28 and a throttling device 10 is interposed between the accumulator 5 and the control mechanism 11. The press has a main cylinder 32 communicating through pipe 39 with the control device 11, and two withdrawal cylinders 36 also communicating with the control device through pipe 37 and distributer 38. Water from a reservoir 1 is fed by pump 2 to the hydraulic accumulator 5 which is loaded by compressed-air bottles 6. The press performs a continuous working cycle determined by the cams on shaft 21: first pre-fill valve 12 opened by cam 22 admits low-pressure liquid from vessel 18, having an overflow valve 19 and safety valve 20, into press cylinder 32 whilst the withdrawal outlet valve 16 is open to permit exhaust through pipe 30 and shock absorber 29 into reservoir 1; valve 12 closes and valve 13 is opened by cam 23 to allow high-pressure liquid from accumulator 5, manually adjustable throttle valve 8, distributer 9, main throttle valve 10 and pipe 4#, to pass into cylinder 32 and effect the forging stroke; withdrawal valve 15 is then opened by cam 25 to allow the highpressure liquid into cylinders 36 and simultaneously the main cylinder outlet valve 14 is opened by cam 24. To change the number of strokes per unit time the speed of motor 28 is varied. To vary the stroke position of the main press platen 33 and saddle 34, throttle valve 10 is regulated manually by a lever 44 in one direction to throttle the supply through pipe 4# to main cylinder 32 which thus reduces the pressing speed and hence raises the bottom dead-centre position of the platen, and in the opposite direction to throttle the withdrawal cylinder supply through pipe 4g which thus lowers the top dead-centre position. Wedges 27 interposed between the cams 22-26 and valve stems may be withdrawn by a common hydraulic motor 54, Fig. 3 (not shown), for stopping the press with the cam shaft running. Interlock mechanism is provided whereby upon re-insertion of the wedges the press platen first moves upwardly. In a modification, Fig. 2, the press platen 33 has a depending rod carrying two stops 61, 62 adjustable by a motor 63 and spindle 64 and co-operating with a spring- loaded lever 66 controlling a pilot valve 70. Throttle valve 10 has its lever 44 connected between differential area pistons 82, 83 of which the smaller 83 is continuously subjected to oil pressure through pipes 75, 75b. When the stops 61, 62 actuate lever 66, pilot valve 70 controls the pressure oil acting on piston 82 and thus varies the throttle valve. The height of pilot valve assembly is adjusted, to suit the position of the stops, by pistons 90, 92 controlled by a rotary valve 86.