GB1153664A - Forming method and apparatus - Google Patents

Abstract

1,153,664. Making hollow-ware; cupping. NATIONAL DAIRY PRODUCTS CORP. 10 Jan., 1967 [21 Jan., 1966], No. 1334/67. Headings B3A and B3Q. [Also in Divisions B5 and B6] A press for forming drawn containers comprises means 17, 37 for clamping the edge of a blank 79 during the drawing operation, and means for creating the clamping pressure, for controlling the maximum clamping pressure and for relieving the clamping pressure. Containers of aluminium foil, steel, tin plate &c. and having a curled edge are produced in a single operation of the press. Attached to the punch-holder 13 of the crank-operated press is a blanking punch 17 which also forms part of the clamp and houses a die 19. A coacting die 39 is carried by a holder 15, and surrounding this die is a draw ring 37 forming the other part of the clamp. One or more rods 47 support the ring 37 on pistons 45 in cylinders 41 connected, through a check valve 63 and a booster 57, to a source of hydraulic pressure 55. Fluid may return to the sump 55 through an adjustable relief valve 65, or through a " dump " valve 69 when rapid release is required. The valve 69, booster 57 and a valve 32 through which hydraulic fluid may be supplied to one or more cylinders 21 in the punch holder 13 are controlled by switches 73, 59 operated by cams 75, 61 rotated by the press-drive. Operation.-Sheet material 77 is fed between the dies by feed mechanism (not shown) and a blank severed by the punch 17 as the punch holder descends. Clamping pressure in the cylinders 41 builds up to the pre-set maximum as the drawing operation proceeds, but is insufficient to prevent the clamped margin from being pulled slowly from between the ring 37 and punch 17, Fig. 4 (not shown). Just prior to the time when the blank would be pulled out of the clamp, the " dump " valve 69 is opened, releasing the clamping pressure as, or just before, the dies 19, 39 close completely. During the last portion of downward travel of the punch-holder 13, and after release of the clamping pressure, the edge (81), Fig. 5 (not shown), of the blank is wiped between the punch 17 and die 39. Just before bottom dead-centre, the " dump " valve 69 is closed and at about the same time the air-booster 57 is operated to force hydraulic fluid, through check valve 63 and conduits 30, 51, into the cylinders 21, 41. This causes the ring 37 and punch 17 to move upwardly for the ring, by means of its annular groove 38, to form a curl, Fig. 6 (not shown), in the rim of the container. A hold-down plate 31 and an ejector pin 83 are provided. The valves 65, 69 may be combined, or valve 65 may also be controlled to function as a " dump " valve. A heat-exchanger may be used in one or more of the lines to keep the fluid at constant temperature. The cylinders 21 may be connected to a separate hydraulic system.