GB533178A

GB533178A - Improvements in or relating to presses for drawing sheet metal or the like

Info

Publication number: GB533178A
Application number: GB27872/39A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1938-10-17
Filing date: 1939-10-13
Publication date: 1941-02-07

Abstract

533,178. Cupping. MACMILLIN, H. FOct. 13, 1939, No. 27872. Convention date, Oct. 17, 1938. [Class 83 (iv)] A sheet metal drawing press comprising a main slide 16, a second slide 30, and a work holder 42 detachably connected to the slide 30 by rods 40 passing through holes 41 in the main slide. The work-piece 13 is placed on the matrix 12 and a valve 51 is operated to admit liquid from a pump 48 and tank 47 to the upper end of a cylinder 20 and exhaust the lower end. This causes the piston 18, slide 16, and a detachable punch 15 to descend and, with these, a slide 33 and hold-down 42, attached thereto by rods 40. Plungers 27 attached to the slide 33 are thus drawn out of cylinders 25, liquid being admitted thereto by non-return valves 56. When the holddown 42 engages the work it is arrested and, as the slide 16 continues to move, acting on the work, liquid in cylinders 36 above heads 44 of the plungers 27 is forced through a passage 45 into the cylinders 25. At this moment an arm 64 of the slide 16 engages a stop 63 thus closing an exhaust pipe 59 which leads from non-return valves 58 and the cylinders 25, so that the pressures in these cylinders, which is indicated by gauges 66, increase to values determined by the setting of adjustable relief valves 67 or safety valves 69. These pressures, acting on the ends 70 of the plungers 27, cause the holddown to act with any desired pressures on the work. After drawing, the valve 51 is reversed, the slide 16 rises to strip the work, then the arm 64 releases the stop 63, the valve 60 opens, the slide 16 engages shoulders 71 on the rods and lifts the slide 33 &c, some liquid from the cylinders 25 being discharged into the bores 36, the bulk being freely discharged during the first part of the up stroke, but through the valves 58 and 60 during the latter part. If unequal pressure in the cylinders 25 is not desired the valves 58 may be omitted and only one valve 67 be used.