GB1271723A - Electrohydraulic transducer apparatus - Google Patents

Abstract

1,271,723. Electrohydraulic forming; making cans. CONTINENTAL CAN CO., Inc. 10 Sept., 1969 [25 Sept., 1968 (2)], No. 44697/69. Headings B3A and B3Q. Apparatus for forming a workpiece T, Fig. 1, e.g. a can or a plastic or paper container, between the flexible wall 23 of a chamber and surrounding die 40, 41 comprises a pair of electrodes 33, 34 within the chamber, a cage 11 supporting the flexible wall and having spaced members 12, 13 at opposite ends of the chamber, means for introducing an electrically conductive fluid into the chamber and for increasing its pressure so as to rough-form the workpiece, and a source of electrical potential for producing a discharge in the fluid between the electrodes to further form the workpiece. The gap 37 between the heads 35, 36 of the screwthreaded electrodes may be adjusted by rotating the electrodes. Coaxially-spaced electrodes may be used, Fig. 3 (not shown), and a piston 121, Fig. 5, for clamping the edge of the workpiece against the die by means of the conductive fluid, which may be a saline solution. After forming the workpiece, the fluid is withdrawn, creating a partial vacuum to lift the piston 121. The apparatus may be embodied in a can styling machine having a rotatable turret 212, Fig. 10, carrying four split dies 213, Fig. 16, electro-hydraulic forming heads and elevatable supports 215 for cans. A can is fed to the support 215 at the receiving station by a wheel 216 and held by vacuum as the support is raised to place the can over the flexible wall of an electrohydraulic forming head 214, Fig. 15. After the support is raised the die-halves 218, 220 close from a part-closed to a completely closed position, and the vacuum is interrupted. Springs 314, Fig. 20, acting on the head of the support, press the can against the forming head before the die is closed. Liquid is then introduced for inflating the can, followed by a spark discharge before the can is discharged by a wheel 223. The turret is turned by a gear 227 so that the supports 215 are elevated by a cam track 302 which operates slides 297 carrying the supports. Above the turret is a stationary cam 383 for operating the die-halves by means of slides 378 and links 362, 370, 375, Fig. 25, on the turret. A post 408, Fig. 33, pivotally-supports contacts 395, 396, through which a pulse of electrical energy may be transmitted to forming head contacts 385, 386 when these are appropriately positioned by rotation of the turret. After the styling operation, the dies are completely opened, the vacuum re-imposed in the holder which is lowered and the can is removed by a wheel 223, Fig. 10. An hydraulic control circuit, Fig. 13 (not shown), includes an isolator (435) between the supply of saline solution to the forming heads and the hydraulic fluid pressurizing the solution. In another construction, the holder may be raised by a fluid motor.