| 摘要 |
<p>Objects of complex shape are cast by the lost wax process in a porous plaster mould. The mould is enclosed in a strong, temp. resistant container, comprising a base with a suction port, a surrounding wall, and a top with a pouring funnel, which can be closed by a pressure tight lid. The units clamp together to form a pressure tight enclosure.S Channels are formed within the mould, against the wall, with connections at the base to the suction port. The port is connected to a suction pump, a vacuum reservoir, a control valve, and vacuum gauges. Vacuum assisted casting using this equipment gives a well filled mould, including undercut recesses, with good detail reproduction. The vacuum reservoir makes the process easy to regulate, and avoids problems of irregularity where direct pumping is employed. The channels in the mould and the connectors to the suction port, are produced when the mould is formed around the wax pattern, either by forms which can be withdrawn and reused, or by disposable shapes which can be burnt out.</p> |
