Luoyang Judian Metal Hot Processing Equipment Co., LTD is mainly engaged in the manufacture of complete sets of equipment in the metal thermal processing industry and the integration of the entire production line.
Vacuum Induction Furnace Body, Accessories and Vacuum System
1. Furnace Body and Auxiliary Devices
The furnace body of a vacuum induction furnace and the auxiliary devices installed on it generally include the equipment required for charging, ramming, melting, pouring and other processes. Figure 2-41 shows the furnace body and auxiliary devices of a horizontal vacuum induction furnace.
The furnace shell is divided into two parts: the movable furnace shell and the fixed furnace shell. The entire smelting process is carried out inside the furnace shell, making it a major component of the furnace.
The furnace shell of a vacuum induction furnace must withstand the strong pressure formed by the internal vacuum, so it must have sufficient structural strength.
Small furnace shells adopt a double-layer structure. The outer layer is made of ordinary steel plate, while the inner layer is welded from non-magnetic austenitic stainless steel plate, with water cooling between the two layers.
Large furnaces partially use a double-layer structure, while most parts adopt a single-layer steel plate structure with external water pipes for cooling.
The contact surface between the movable and fixed parts of the furnace shell, as well as the connecting surfaces between the devices installed on the furnace shell and the furnace shell, must be sealed with vacuum rubber parts.
The internal structure of a horizontal vacuum induction furnace is shown in Figure 2-42. Inside the furnace shell, there are devices such as an inductor, crucible support, ingot casting device, charging chute, and coaxial rotating electrode.
Outside the furnace shell, there are devices such as a charger, ramming rod, temperature measuring and sampling device, and observation window.
The power supply device is also installed on the furnace body. Small furnaces use water-cooled coaxial rotating electrodes, while large furnaces use water-cooled cables insulated from the furnace shell.
Figure 2-43 shows the structure of the water-cooled coaxial rotating electrode used in a small vacuum induction furnace. The water-cooled coaxial rotating electrode is divided into inner and outer layers.
It is made of copper tubes. The outer layer is called the outer electrode, and the inner layer is called the inner electrode. An insulating layer cast from epoxy resin and quartz sand material is used between them.
Both the inner electrode and the outer electrode are cooled by water.
The functions of the water-cooled coaxial rotating electrode are as follows:
It transmits medium-frequency current to the inductor. The current circuit is: outer electrode → inductor → inner electrode.
It supplies cooling water to the inductor.
It tilts the crucible.
It can be seen that the water-cooled coaxial rotating electrode is a key component of small furnaces. It must be carefully used and maintained, and spare parts should be prepared when necessary.
Furnace models using the water-cooled coaxial rotating electrode structure include ZG-0.01, ZG-0.025, ZG-0.05, ZG-0.2 and other types.
The parts of the furnace body that need cooling include the furnace shell, ramming rod, temperature measuring device, sampling device, inductor, large flange, coaxial rotating electrode, cable and current collecting device. The pressure and flow rate of cooling water should ensure normal smelting.
In addition, large furnaces are also equipped with auxiliary equipment such as a charging chamber and vacuum unit, furnace shell moving device, and ingot charging and discharging device.
3. Vacuum System of Vacuum Induction Furnace
The smelting vacuum degree of the furnace is usually within the range of 10^-2 to 10^-3 Torr. The smelting vacuum degree of large furnaces is lower than that of small furnaces.
To maintain the smelting vacuum degree, a suitable vacuum unit must be selected to meet the vacuum requirements.
The vacuum system of the furnace includes the vacuum chamber, furnace shell, vacuum unit, pipelines, vacuum valves, measuring instruments, sealing elements and other components.
This refers to the vacuum degree maintained by the furnace during operation. It can also be divided into melting vacuum degree, refining vacuum degree and pouring vacuum degree.
The smelting vacuum degree is the main parameter indicating the quality of the furnace vacuum system.
2. Ultimate Vacuum Degree
This refers to the highest vacuum degree that the furnace can reach when it is empty at room temperature.
It is an important indicator for evaluating the pumping capacity of the vacuum unit and the air leakage and gas release of the furnace system.
3. Pumping Speed
This refers to the amount of gas extracted from the furnace by the vacuum unit per second.
The faster the pumping speed, the shorter the time required to reach the needed vacuum degree, and the higher the efficiency of the vacuum unit.
4. Pressure Rise Rate
This refers to the value by which the vacuum degree in the furnace body or other vacuum chamber decreases per unit time.
It is an indicator of the leakage condition of the furnace.
