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Medium frequency furnace medium frequency induction melting furnace molten iron with induction electricity is how is it?
The medium frequency induction melting furnace is electromagnetically induced and heated, and the induction current is generated on the charge (steel water), otherwise the charge will not melt. The operator or the molten iron will have a feeling of being numb. First, the operator must wear insulated work shoes, the ground should be kept dry, and the rubber pad or plank should be placed at the location of the operator station.
What is the role of the yoke in the intermediate frequency induction melting furnace?
Providing a magnetic circuit to enhance the magnetic conduction capability, and only function as a magnetic line transmission in the magnetic circuit;
Preventing magnetic flux leakage to the outer magnetically conductive material; it can improve the melting efficiency and reduce the interference and protection.
The yoke shielding is characterized in that a yoke is made of a magnetic material and is mounted on the periphery of the induction coil, so that as many magnetic fluxes as possible form a loop through the yoke to reduce the leakage magnetic field and achieve the purpose of shielding.
In order to ensure the quality of the iron core stacking, the silicon steel column installation and production project department produces a special positioning welding and silicon steel sheet stacking platform, and the laminated assembly adopts a curved stacking process, which has a good compacting effect and less magnetic leakage. It is more close to the induction coil, improves the magnetic flux direction, eliminates the local magnetic flux saturation of the iron core at the joint, reduces the no-load loss and no-load current of the iron core, fully utilizes the magnetic permeability area of the silicon steel sheet , and reduces the medium frequency induction. The possibility of local heating of the furnace body of the melting furnace. The contact surface of the yoke cover stainless steel plate and the silicon steel sheet is separated by a high-grade gold mica plate, the outer side is clamped by stainless steel, and a specially designed copper heat pipe is arranged between the yoke and the stainless steel plate clamp, or in a stainless steel plate. welded on the heatsink or cooling tank, the water cooling of the yoke, the yoke is to ensure that the normal state, on both sides of the yoke use of 4 - 8 stainless steel screws holding the locking bolt, to avoid elevated temperatures deformed cover More than 60 % of the surface of the induction coil effectively collects magnetic lines of force into the molten pool to prevent heat generation of the furnace shell and improve system efficiency. The performance is stable and the coil is reliably supported , which improves the overall strength of the furnace. Medium frequency induction melting furnace yoke, in order to ensure the process control of the quality of silicon steel column, the parameters of silicon steel sheet are inspected before stacking, and each silicon steel sheet is visually inspected before stacking. The copper tubes pass the pressure and water-passing experiments, and the outer layer is sprayed with DuPont's Dote anti-arc insulation paint , which effectively prevents the magnetic and rust of the silicon steel sheet from ensuring the quality of the yoke silicon steel sheet.
How to choose the right induction melting furnace ?
Induction melting furnace heating fast speed, high efficiency, low burning, heat loss is small, the room temperature is relatively low, reduced smoke generation, save energy and improve productivity, improve working condition, reduce labor intensity, clean room and environmental effect is remarkable . Especially for cast iron, the induction of melting furnace to obtain low-sulfur iron is unmatched by cupola. When selecting a melting furnace, the foundry company should select the following factors according to the transformer capacity, production requirements, investment quota, etc., when purchasing equipment.
1. What are the electrical conditions for induction melting furnaces?
1.1 How to choose the capacity of the intermediate frequency induction melting furnace transformer?
At present, for the industry commonly used SCR full-bridge parallel inverter IF power supply, the relationship between the transformer capacity and the power supply value is: the value of the transformer capacity = the value of the power supply × 1.2. For the IGBT half-bridge series inverter IF power supply (commonly known as a Tow two, one smelting one insulation, two working at the same time) The numerical relationship between transformer capacity and power supply is: value of transformer capacity = value of power supply × 1.1. Transformer is a rectifier transformer. In order to reduce the interference of harmonics, try to use the special-purpose machine, and configure one rectifier transformer for one intermediate frequency power supply.
1.2 How to choose the line voltage of the intermediate frequency induction melting furnace?
For medium frequency power supply below 1000KW , three-phase five-wire 380V , 50Hz industrial power is used, and 6- pulse single-phase rectified intermediate frequency power supply is configured. For medium frequency power supply above 1000KW , the focus is on using 660V incoming voltage (some manufacturers use575V or 750V , because 575V or 750V is a non-standard voltage level, the accessories are not good to buy, it is recommended not to use)) Configure 12- pulse double-rectifier IF power supply for two reasons: one is to increase the rated working voltage by increasing the incoming line voltage; The harmonics generated by high power will interfere with the power grid. The double rectifier can obtain a relatively straight DC current. The load current is a rectangular wave, and the load voltage wave is close to a sine wave, which reduces the impact of grid interference on other devices. Some users blindly pursue high voltage (some1000KW 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 cause the life of electrical components. Shortening, copper platoons, and cables are exhausted, which greatly reduces the life of the electric furnace. 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) and ultimately suffer from the use of electric furnace manufacturers.
2. Determine the model of the medium frequency induction melting furnace according to the capacity requirements.
In general, the weight of the intermediate frequency induction melting furnace can be determined according to the weight of the individual piece and the weight of the molten iron required for each working day , and then the power and frequency of the intermediate frequency power supply are determined. 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 the table below .
Medium frequency induction melting furnace selection parameters | |||
Serial number | Melting / T | Power / KW | Frequency / HZ |
1 | 0.15 | 100 | 1000 |
2 | 0.25 | 160 | 1000 |
3 | 0.5 | 250 | 1000 |
4 | 0.75 | 350 | 1000 |
5 | 1 | 500 | 1000 |
6 | 1.5 | 750 | 1000 |
7 | 2 | 1000 | 500 |
8 | 3 | 1500 | 500 |
9 | 5 | 2500 | 500 |
10 | 8 | 4000 | 250 |
11 | 10 | 5000 | 250 |
12 | 12 | 6000 | 250 |
13 | 15 | 7500 | 250 |
14 | 20 | 10000 | 250 |
It can be seen from the table that the power density of the domestic medium frequency induction melting furnace is basically around 500 KW / ton, which is lower than the theoretical optimum value of 600-800 KW , 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 supply can be increased by 100 KW/ ton while the capacity of the furnace is constant .
3. Structural choice
In general, the capacity of the intermediate frequency induction melting furnace can be determined according to the weight of the individual piece and the weight of the molten iron required for each working day , and then the power and frequency of the intermediate frequency power supply are determined.Induction heating equipment is a non-standard product. At present, there is no standard in the country. The general configuration of the industry is shown in the following table.
project | Steel shell furnace | Aluminum shell furnace |
shell material | Steel structure | Aluminum structure |
Tilting mechanism | Hydraulic cylinder | Reducer |
Hydraulic power station | Have | no |
Yoke | Have | no |
Furnace cover | Have | no |
Leakage alarm | Have | no |
Energy consumption | 580Kw.h/t | 630Kw.h/t |
life | 10 years | 4-5 years |
price | high | low |
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