Patent GB-1419324-A (GB)
Title: Precision stamping press
IPC: B21D28/20
Filed: 1973-03-01
Abstract: 1419324 Punching HYDREL AG 1 March 1973 [3 March 1972] 10146/73 Heading B3W A precision stamping press comprises first and second interconnected frame members 3, 2, tables 24, 9 axially realtively displaceable by hydraulic means for use selectively with either a blanking punch 45 which is movable, and an annular prong ring 25 which is fixed, relative to the table member 24 or a fixed blanking punch (75), Fig. 3 (not shown), and a movable prong ring (76). The movable punch is used when the piston rod is locked against vertical movement relative to the frame member 3 and the movable prong ring when the table member 24 is so locked. Mounted in a cylinder in the frame member 3 is a piston 33 fixed though adjustable, on a piston rod 34, the table member 24 forming part of a piston 32 surrounding, and being movable relative to, the piston rod 34. A changeover device comprises two distance pieces 55, 57 relatively adjustable between positions in which the table member 24 is respectively movable, and not movable, relative to the frame member 3 and an actuating device 58 for causing the adjustment and which controls a valve 63 which supplies fluid selectively to one side or the other of the piston 33. As shown, the distance pieces are pins 57 fixed to the frame member 3 and a ring 55 rotatable to move holes 56 in and out of alignment with the pins. In operation, with the Fig. 1 tool arrangement, rotation of the ring 55 to align the holes 56 with the pins 57 causes fluid to be supplied through ducts 66, 71 to the underside of piston 33, driving pistons 32 and 33 as far apart as shoulders 74 and 73 on the cylinder allow and thus locking the piston rod against vertical movement. Fluid is then supplied through inlet 16 to the underside of piston 6 which first raises the die 21 to press the blank 27 against the prong ring 25 and then moves the ring 25 and the table 24 upwards, the pins 57 entering holes 56, while the punch 45 remains stationary thus punching a blank from the sheet 27. Fluid is then supplied through inlet 17 to lower the table 9 and through inlet 18 to actuate an ejector 15. In operation, with the Fig. 3 arrangement (not shown), the punch (75) is fixed to the table 24 and the annular prong ring (76) is mounted on pins (77) which are slidable in apertures 53 and abut alignment pins 52 fixed to the piston rod 34. Rotation of the ring 55 to move the holes 56 out of alignment with the pins 57 locks the table member 24 against vertical movement relative to the frame member 3 and causes fluid to be supplied through duct 67 to the upperside of the piston 33 to close the gap between pistons 32 and 33. Upward movement of the piston 6 moves the ring (76) and, via pins (77) or 52, the piston rod 34 while the punch remains stationary, the pins 57 not being aligned with the holes 56. A key 43 and pins 52 prevent rotation of the punch 45 or (75). The piston 33 is adjustable on the piston rod 34 by means of a sleeve 35 and chain and crank drive 41, 42. The rod 34 is lowered or raised, to compensate for shortening of the punch 45, or (75) respectively, due to re-grinding.