Patent GB-610628-A (GB)
Title: Improvements relating to punch presses
IPC: B21D24/14
Filed: 1946-04-11
Abstract: 610,628. Cupping. VERSON ALLSTEEL PRESS CO. April 11, 1946, No. 11214. Convention date, April 11, 1945. [Class 83 (iv)] A punch press comprises a punch slide, a blank-holder slide mounted for reciprocation within the punch slide and pins extending from a blank-holder into the punch slide for engagement by the blank-holder slide. The press frame comprises a bed 12 secured to four upright members 14 connected at their upper ends to a crown 16. A slide 18 mounted for reciprocation between the members 14 in guides 20 is of box-like form comprising vertical side and end walls and horizontal top and bottom walls 48 and 58, the latter having a number of tapped holes 74 so that a punch A may be bolted thereto in a selected position and a number of blank holes 84 through which pass pins 86 by which a blank-holding ring B is pressed down on to the work W and other pins 90 by which the ring B is suspended from the slide 18 when the latter is in its upper idle position. The lower part of the slide 18 is strengthened by means of vertical portions 52, 54 and a horizontal partition 56. In addition, a number of tubes 60 extend vertically between the top and bottom walls of the slide. Inwardly of the four corners of the slide are vertical posts 66 secured between the upper wall 48 and plates 64 welded to the side and end walls and the partitions 52, 54. These posts serve as guides for the blank-holding slide 28 mounted within the slide 18 and comprising upper and lower walls 130, 132, vertical side and end walls 124 and vertical strengthening partitions 134, 136. The slide 18 is operated by a piston 24 within a cylinder 26 and the slide 28 by two or more pistons 30 in cylinders 32 and extending downwardly through openings in the upper wall of the slide 18. The bed 12 carries a bolster plate 22 on which rests the lower die C and through which operates a cushioning and ejecting member 34 which is also operated hydraulically. The hydraulic power for operating the press is supplied by a pump 168 driven by a motor 172 and a smaller pump 170 driven by a motor 174, these pumps and motors being mounted in the crown of the machine. With the parts in the position shown in Fig. 3, the depression of a starter button operates the motors 172 and 174 and the two slides move slowly towards the work under gravity, the pumps serving as metering devices for fluid below the pistons. Before the blankholder contacts the work, a cam operates a switch to close a valve, causing the pumps to build up pressure in the cylinders 26 and 32 for the pressing and holding operations and the cupping of the blank takes place. The downward movement of the slide 18 continues until the pressure in the hydraulic system reaches a predetermined value, when a pressureresponsive controller is operated to cause a return movement. The cushioning device is then moved upwardly to act as an ejector. The hydraulic and electric control circuits are described with reference to Fig. 10 (not shown). During its upward movement, the slide 18 contacts and raises the slide 28, cushioning devices 96 carried by the slide 18 serving to cushion the impact between the slides.