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Maintenance and maintenance methods of vacuum casting furnaces
Release Time：
2023-09-21
What are the maintenance and maintenance methods for vacuum casting furnaces?
A vacuum casting furnace is an electric furnace that melts metal by directly heating it with an arc in a vacuum chamber. The gas in the furnace is thin, mainly relying on the vapor of the molten metal to generate an arc. To stabilize the arc, direct current is generally supplied. According to the melting characteristics, it is divided into metal remelting furnaces and casting furnaces. According to whether the electrodes are consumed (melted) during the melting process, it is divided into consumable furnaces and non-consumable furnaces. Most of the industrial applications are consumable furnaces. Vacuum arc furnaces are used to melt special steels, active and refractory metals such as titanium, molybdenum, and niobium.
Arc electric heating can be considered arc resistance electric heating. Arc (arc resistance) stability is a necessary condition for the normal production of the furnace. AC arc furnaces usually use industrial frequency electricity. To stabilize the arc, the vacuum casting furnace power supply circuit must have appropriate inductive reactance, but the existence of inductive reactance will reduce the power factor and electrical efficiency.
Reducing the current frequency is a way to develop AC arc furnaces. The arc resistance value is quite small. To obtain the necessary heat, the furnace needs a considerable working current, so the resistance of the furnace short network should be as small as possible to avoid excessive circuit loss. So how to do a good job of maintenance and maintenance? There are two methods, as follows:
1. Draw a low vacuum according to the PLC program: Close all vacuum valves of the vacuum casting furnace, start the mechanical pump, and after it runs normally (about 1-2 minutes), open the low vacuum valve leading to the furnace, that is, the upper disc valve, to pre-evacuate the furnace to a low vacuum;
2. Draw a high vacuum according to the PLC program: Open the lower disc valve to pump the diffusion pump. When the vacuum degree reaches below 15Pa, the vacuum casting furnace system automatically turns on the diffusion pump for preheating. Generally, after about 45 minutes, the diffusion pump starts to work, and the upper disc valve can be closed, and the main blocking valve can be opened at the same time. When the vacuum degree reaches 1.33 × 10Pa or more, the heating button can be turned on to heat the sample.
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