GB1294240A - Conductor-initiated electrohydraulic forming processes - Google Patents

Abstract

1294240 Electrohydraulic forming SIEMENS AG 2 March 1970 [6 March 1969] 9961/70 Heading B3Q [Also in Division H1] A method of electrohydraulic forming comprises connecting a first initiating conductor across the electrical supply to produce a first discharge, and in the "dark interval" of the first discharge producing a second discharge by connecting a second initiating conductor across the supply in parallel with the first. The "dark interval" is the period, following the discharge, during which metallic conduction is prevented by excessive atom spacing. In an example, Fig. 2A, the initiating wires 25, 26, 27 are connected in sequence to the capacitor battery 21 by switches 29, 210, 211, wire 36 being connected in the dark period following the disruption of wire 25 in workpiece 22, and wire 27 being connected after wire 26. The pressure waves produced by a discharge may be used to trigger a further discharge, or thermal action may damage insulation and initiate another discharge. Thus vaporization of wire 35, Fig. 3, destroys a polyethylene insulation 37 on a second wire 36. A disc 310, carrying part of the insulation 37, is raised by the pressure wave and permits contact between the wire 36 and the electrode 33 for producing a further pressure wave. Alternatively, concentric conductors (not shown), may be used so that a discharge through one layer weakens an underlying layer of insulation adjacent the electrode. Voltage remaining during the dark period punctures the insulation and continues the discharge through the succeeding conducting layer.