Patent GB-570435-A (GB)
Title: Hydraulic press for forming sheet materials
IPC: B21D24/14
Filed: 1943-07-21
Abstract: 570,435. Cupping. FLOWERS, P. E., MACMILLIN, H. F., and ERNST, W. July 21, 1943, No. 11908. [Class 83 (iv)] A hydraulic cupping press has the draw-ring fitted with an annular die for blanking out prior to drawing and is fitted with controls to be operable during one and the same cycle to carry out the blanking and also the drawing action. The punch 47, Fig. 1, is carried by a platen 6 operated by a hydraulic ram 5. The draw-ring 57 is carried by an auxiliary platen 49 and is fitted with a blanking-out cutter 58. Rams 60, 61 on the platen 49 engage cylinders 30 in the platen 6 having hollow extensions 32 that act as rams in cylinders 3 in the press-head J. Stock 50 is inserted be- . tween the die 54, Fig. 5, and cutter 58, and the main pump 13 is started. Main and starter switches (not shown) are closed in an electrical control system prising a series of interlocked and sequentially acting solenoid-controlled switches, some having dashpot control. A solenoid 25 is energized, drawing down the armature 24 and, by a three-armed lever 22, pivoted at 22a and linked to the pump control at 21, sets the pump for full delivery forward stroke supplying fluid above the ram 5 and withdrawing it from below. During this rapid downstroke, the rams 31, 32 create a suction in the cylinders 3 and the check valves 43, 44 admit fluid from the tank 8 into the cylinders 30. At this time valves 34, 46 are in the position shown in Fig. 5, due to the pull of solenoids 41, 41a and connection to the tank 8 through these valves is interrupted. A surge valve 7 in the cylinder 2 is open to admit fluid from the tank. When blanking-out begins, pressure builds up in the cylinder 2 and the valve 7 closes. The platen 6 commences to move towards the platen 49 and the vanes 60, 61 create pressure in the cylinders 30 and the check valves 43, 44 close. The full pressure exerted on the ram 5 is now conveyed to the cutter 58 and the blank is cut out. When the pressure in the cylinder 2 rises sufficiently, a high-pressure control valve 18 opens a switch, de-energizing solenoid 25 and permitting a spring (not shown) to move the control of the pump 13 into full delivery return stroke position. A low-pressure control valve 19 is not affected at this time, since a valve 121 is closed. The ram 5 therefore commences to move upwards, but solenoids 41, 41a are cut out and springs 37 shift the valves 34, 46 and excessive pressure in the cylinders 30 is released through relief valves into the tank: The solenoid 25 again operates to restore the pump to full forward delivery and the ram 5 again descends. Solenoid 123 opens valve 121, rendering valve 69 operative, and draw-ring 57 engages the blank and is arrested. further movement of the ram creates the required pressure in the cylinders 30, any excess being released through the open valves 34, 46. On the pressure in the main cylinder 2 rising at the end of the cupping stroke, the low-pressure control valve 19 operates, opening a switch, causing the pump control to shift to full delivery return stroke position. Solenoid 123 is again operated to close valve 121. As the platen 6 ascends, collars 65 on rods 63 engage the auxiliary platen 49 and raise the draw-ring. Strippers 55 eject the scrap into a waste collector (not shown). Near the end of the return stroke an arm 28 brings a rod 27 into contact with an arm of the lever 22 and shifts the pump control to neutral, and the press stops with all the parts as shown in Fig. 1, ready to commence a new cycle. A selector switch may be provided to cause antomatic initiation of a new cycle by the closing of a switch 85. The return stroke can be controlled by a limit switch 119, operated by an arm 124, instead of by the switch 19. When the switch 19 is to operate the switch 119 is moved out of the path of the arm 124. Similarly, the slight return of the ram between the blanking and cupping may be controlled by a switch 86 instead of by the valve 18. In a modification, the main ram 130, Fig. 9 actuates a platen 132 having cylinders 133 in which rams 134, connected to the draw-ring holder 135, work. Check valves. (not shown) are provided as in the previous form. On operating the cycle, the ram 130 moves down and the valve 138 being closed the holder 135 moves with it. After blanking is complete, the main platen or an arm connected to it closes a switch controlling a solenoid 147 that opens valves 127, 138, relieving pressure in the cylinders 133 through relief valve 140. This pressure in the main cylinder has already fallen below that required to operate the control valve 129. The cupping stroke now commences, at the end of which the rise in pressure opens the valve 129, causing reversal of the ram 130. At the end of the return stroke, a limit switch is opened and the press is brought to rest as before. In a further modification, the pressure in the main ram cylinder acts on a spring-pressed piston in a separate cylinder and the piston-rod carries a pivoted latch yielding in one direction, but rigid in the other to operate a limit switch. In another modification, generally similar to that first described, a slow-down arrangement is provided to control the movement of the main press ram. In two other modifications, the draw-ring is operated independently of the press ram, the modifications differing in the arrangement of the pumps.