Lost wax patterns for casting tooth crowns - made in appts. which prevents damage or distortion of the pattern

摘要

Appts. for casting wax patterns, esp. for mfg. tooth crowns, using one or more moulds, each consisting of a cope and a drag. At least the drag is made of an elastomer and is located in a rigid frame; and the drag forms the concave part of the mould. The ingate for the wax passes through the cope and enters the drag, and pressure is exerted on the base of the flexible drag to eject the wax pattern without damage. A compressed air inlet is provided on the ingate for removing the pattern from the cope. The press. on the base of the drag can be exerted by (a) a pressurised liq. or gas; or (b) pegs driven upwards by mechanical press. An automatic casting machine is pref. employed using moulds located on a turntable underneath a heated tank fitted with a closable outlet nozzle for the molten wax. The cope is binged on the drag and, after the mould is opened, compressed air blows the patterns down a chute to a collection bin.