The difference between the price of medium frequency induction melting furnace

The difference between the price of medium frequency induction melting furnace

When selecting the medium frequency induction melting furnace, the foundry company should select the following according to the transformer capacity, production requirements, investment quota, etc., when purchasing equipment.

1. Medium frequency induction melting condition

1.1 IF induction melting transformer capacity

At present, for the SCR full-bridge parallel inverter IF power supply , the numerical relationship between transformer capacity and power supply is: the value of transformer capacity = the value of power supply x 1.2

For IGBT half-bridge series inverter intermediate frequency power supply (commonly known as one for two, one for melting one insulation, two for simultaneous operation), the numerical relationship between transformer capacity and power supply is: value of transformer capacity = value of power supply x 1.1

Transformer is a rectifier transformer In order to reduce the interference of harmonics, it is as far as possible for the special plane, that is, one intermediate frequency power supply is equipped with a rectifier transformer.

1.2 medium frequency induction melting furnace incoming line voltage

The intermediate frequency power supply for the medium frequency induction melting furnace below 1000KW generally adopts three-phase five-wire 380V, 50HZ industrial power, and is equipped with a 6-pulse single-rectified intermediate frequency power supply; for medium-frequency power supplies above 1000KWY, it focuses on the use of 660V incoming voltage ( Some manufacturers use 575V or 750V, because 575VZ or 750V is a non-standard voltage level, accessories are not good to buy, it is recommended not to choose to use) 12-channel dual-rectifier IF power supply, for two reasons: First, improve the line voltage The rated working voltage; the second is that the harmonic generated by the high power will interfere with the power grid. The double rectification can obtain a relatively straight DC current. The load current is a rectangular wave, and the load voltage is close to a sine wave, which reduces the impact of grid interference on other equipment.

Some users blindly pursue high voltage (some 1000KW use 900V line voltage), and achieve energy saving since low current. I don't know if this is at the cost of the life of the electric furnace. It is not worth the loss, high voltage is easy to shorten the life of electrical components. , copper platoon, cable fatigue, so that the life of the electric furnace is greatly reduced. In addition, for high-voltage electric furnace manufacturers, the raw materials are reduced in terms of materials, and the cost is saved. Electric furnace manufacturers are certainly willing to do so (high-priced low-cost.) The ultimate loss is still the use of electric furnace manufacturers. 

2. Capacity requirements

In general, the capacity of a medium frequency induction melting furnace can be determined by the weight of a single piece and the weight of molten iron required per working day. Then determine the power and frequency of the intermediate frequency power supply.Induction heating equipment is a non-standard product. At present, there is no standard in the country, and the general configuration of the industry is shown in Table 1.

Table 1 Medium frequency induction melting furnace selection parameters

It can be seen from Table 1 that the power density of domestic medium frequency induction melting furnace is about 500KW/ton, which is lower than the theoretical optimal value of 600-800KW, mainly considering the life of the lining and production management. At high power density, electromagnetic stirring will produce a strong scouring of the lining, and the requirements for lining materials, furnace building methods, melting processes, materials, and auxiliary materials are high. According to the above configuration, the melting time per furnace is 75 minutes (including feeding, salvaging impurities, quenching and tempering time). If it is necessary to shorten the melting time per furnace, the power density of the power source can be increased by 100 KW/ton while the capacity of the furnace body is constant.

3. Selection of structure of medium frequency induction melting furnace

According to industry practice, the supply melting furnace of aluminum alloy structure with the reducer as the tilting method is commonly known as the aluminum shell furnace. The induction melting furnace of the steel structure with the hydraulic cylinder as the tilting furnace is commonly called the steel shell furnace. The difference between the two is shown in Table 2 and Figure 1.

Table 2 The steel shell furnace and the aluminum shell furnace are different (take 1 ton cast iron furnace as an example)

Compared with the aluminum shell medium frequency induction melting furnace , the advantages of the steel shell medium frequency induction melting furnace are five points:

 1) Sturdy and durable, beautiful and generous, especially for large-capacity furnaces, which require a strong rigid structure. From the safety point of the tilting furnace, try to use steel shell furnace.

2) The yoke made of silicon steel sheet shields and emits magnetic lines generated by the induction coil, reduces magnetic leakage, improves thermal efficiency, increases production, and saves energy by about 5%-8%. 

3) The presence of the furnace cover reduces heat loss and increases the safety of the equipment.

4) Long service life, aluminum is more oxidized at high temperature, resulting in metal toughness fatigue. At the foundry enterprise site, it is often seen that the aluminum shell furnace shell used for one year or so is broken, and the steel shell furnace has much less leakage current, and the service life of the equipment greatly exceeds that of the aluminum shell furnace.

5) Safety performance The steel shell furnace is much better than the aluminum shell furnace. When the aluminum shell furnace is smelted, it is easily deformed due to high temperature and heavy pressure, and the safety is poor. The steel shell furnace uses a hydraulic tilting furnace and is safe and reliable.

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