The melting temperature has a significant impact on the quality of the ingot. For example, if the temperature is too high, it is not only easy to produce defects such as coarse grains, cracks, and segregation, but also promotes the interaction between the metal and the furnace gas, slag, flux, and furnace lining, increases the oxidation and volatilization losses of the metal, and promotes the metal to absorb gas; If the temperature is too low, it will reduce the slag removal effect of the melt and make it difficult to operate the ingot. Therefore, it is crucial to correctly control the melting temperature and select the outlet temperature. Therefore, the lining material has an impact on the temperature control in front of the copper alloy furnace.
(1) Discharge temperature
Usually, during induction furnace melting, the temperature at which the melt is discharged is used as the casting temperature simultaneously. The principles for determining the discharge temperature are: ① ensuring a certain fluidity of the metal liquid; ② Ensure the normal operation of casting and prevent defects such as cold shuts and slag inclusions; ③ Ensure the gas precipitation during the solidification process of the melt, as well as the smooth floating and discharge of various inclusions from the liquid cavity; ④ According to the casting characteristics of different alloys, it is recommended to use low-temperature tapping as much as possible while ensuring the normal casting operation.
When melting copper and copper alloys in large and medium-sized cored induction furnaces, immersion thermocouples can be fixed and installed in the furnace for continuous temperature measurement.
(2) Control of furnace front temperature
The temperature control of the lining material in an induction furnace can be divided into indirect and direct control methods.
The indirect control of temperature is usually achieved by changing the voltage, current, and power applied to the inductor, that is, using an automatic adjustment system of voltage, current, or power.
Direct temperature control refers to an automatic control system that takes the temperature of the furnace lining material as the direct control object. Usually, on the basis of automatic voltage or power control, units such as temperature regulators, temperature transmitters, and temperature setters are added. The simplest temperature automatic control system is to send the temperature thermocouple signal to the XCT dynamic coil temperature indicator regulator, which outputs the signal to the contactor to achieve automatic temperature control.
