Patent ID: 6820679
Filing Date: 2004-11-23
Classification: B21J,B22D

Abstract:
An improvement in a method of primary forming a metal by pressure die-casting, said method comprising the steps of loading molten metal into a casting chamber, filling a mold cavity with metal from the casting chamber by pressing a casting plunger into the casting chamber toward an anvil, the mold cavity comprising a two piece metal mold, cooling the metal inside the mold cavity to form a solid workpiece, optionally heat-treating the workpiece after solidification, and opening the mold by separating the mold halves to release the workpiece, the improvement comprising the steps of:forming a first closed electrical circuit running through the metal between first and second electrodes, said first closed circuit being made operable by applying a voltage between said first and second electrodes during a first of said steps; and forming a second closed electrical circuit running through the metal between third and fourth electrodes, said second closed circuit being made operable by applying said voltage between said third and fourth electrodes during a second of said steps: wherein at least one of said third and fourth electrodes is neither said first electrode nor said second electrode.