| 摘要 |
Dental castings are made, e.g. crowns, bridges, prostheses, by melting 5-100g metal or alloy, esp. 20-70g noble metal alloys, or 10-50g Co-Cr alloy, in a ceramic crucible. A high-frequency induction coil surrounds the crucible; and the transition from the solid to the molten state is detected by the sudden increase (Sa) of the current flowing through the coil. Signal (Sa) is used for raising the temp. of the melt is a subsequent prescribed time, followed by casting in a mould. Signal (Sa) can be indicated optically or acoustically; and/or used to start the automatic casting of the melt. A thermocouple is inconvenient in view of the small amt. of the melt; the invention is superior to visual observation which is hindered by slag on the melt. |
