GB256865A - Improvements in and relating to blank-holders for presses for drawing sheet metal - Google Patents

Abstract

256,865. Fitzpatrick, H. D., (Marquette Tool & Manufacturing Co.). Feb. 9, 1926. Cupping.-A multiplestage press for drawing sheet metal comprises a moving die 11 and a stationary die 13, the blank 50 being held by a draw-ring 18 during the first stage and by a draw-ring 14 during the second stage, the ring 14 being locked during the first stage by fluid-pressure which is controlled by means connected to the draw-ring 18. The bed 10 carries a bar 23 supporting superposed stationary cylinders 25, 26, the latter of which telescopes within a cylinder 21 upon which rest pins 20 supporting the draw-ring 18. A piston 43 within the cylinder 25 has a rod 41 attached at its lower end to a cross-bar 36 whereby it may be actuated at an adjustable point in the working-stroke of the press by rods carried by the cylinder 21, such actuation serving to release the upper end 44 of the rod 41 from contact with the piston-rod 28 supporting the draw-ring 14, thereby enabling the second stage of the drawing operation to be effected. The draw-rings may be prevented from returning with the upper die by fluid admitted through pipes 53, 32, 51, Fig. 3, as controlled by three-way valves 59 actuated by a bar 61 connected to a moving part of the press.