Medium frequency induction melting furnace heating speed, high efficiency, less burning loss, and less heat loss, the workshop temperature is relatively low, reduce smoke and dust, save energy, improve productivity, improve working conditions, reduce labor intensity, purify the workshop environment and other aspects of the effect are significant. Especially for cast iron, induction melting furnace is beneficial to obtain low sulfide fluid in which cupola can not be compared. Casting enterprises in the selection of intermediate frequency melting furnaces should be based on transformer capacity, output requirements, investment amount as the selection standard, in the purchase of equipment should pay attention to the following matters.
1. Intermediate frequency induction melting power consumption conditions
Intermediate frequency induction melting transformer capacity
At present, for the SCR full-bridge parallel inverter intermediate frequency power supply commonly used in the industry, the numerical relationship between the transformer capacity and the value of the power supply is: the value of the transformer capacity = the value of the power supply x 1.2
For IGBT half-bridge series inverter intermediate frequency power supply (commonly known as one drag two, one smelting and one insulation, two working at the same time), the numerical relationship between transformer capacity and power is as follows: the value of transformer capacity = the value of power x 1.1
In order to reduce the interference of harmonics, the transformer is a rectifier transformer.
2. Capacity requirements
In general, the capacity of an intermediate frequency induction melting furnace can be determined according to the weight of a single piece and the weight of molten iron required for each working day. Then determine the power and frequency of the intermediate frequency power supply. Induction heating equipment belongs to non-standard products. The configuration can be seen in the table below.
It can be seen from the table that the power density of the international intermediate frequency induction melting furnace is basically around 500KW/ ton, which is lower than the theoretical optimal value of 600-800KW, mainly considering the lining life and production management. Under high power density, electromagnetic stirring will have a strong scouring on the lining, which has higher requirements on lining material, furnace building method, melting process, material, and auxiliary materials. According to the above configuration, the melting time of each furnace is 75 minutes (including feeding, fishing impurities, and tempering time). If it is necessary to shorten the melting time of each furnace, the power density of 100KW/ ton can be increased without changing the furnace capacity.
3. Selection of structure
According to industry custom, the supply melting furnace of aluminum alloy structure with speed reducer is commonly known as aluminum shell furnace. The induction melting furnace of steel structure with a hydraulic cylinder as a tilting furnace is commonly known as a steel shell furnace.
1) Solid and durable, beautiful, and generous, especially large capacity furnace body, need strong rigid structure, from the safety Angle of dumping furnace, try to use a steel shell furnace.
2) Magnetic yoke made of silicon steel shields and emits magnetic field lines generated by induction coils, which reduces magnetic flux leakage, improves thermal efficiency, increases output, and saves about 5%-8% energy.
3) The presence of furnace cover reduces heat loss and also improves the safety of the equipment.
4) Long service life, aluminum oxidation at high temperature is more serious, resulting in metal toughness fatigue. In the casting enterprise site, often see the use of about a year of aluminum shell furnace shell broken, and steel shell furnace due to less magnetic flux leakage, equipment service life is much longer than aluminum shell furnace.
5) The safety performance of the steel shell furnace is much better than aluminum shell furnace, aluminum shell furnace is melting due to high temperature, heavy pressure, aluminum shell easily deformation, poor safety. Steel shell furnace using hydraulic tilting furnace, safe and reliable.
4. After-sales service
Good after-sales service is the guarantee of equipment quality, mechanical and electrical products out of trouble is inevitable, this will need good after-sales service, regular manufacturers have enough technical personnel and the ability to guarantee after-sales service. Intermediate frequency induction melting furnace before leaving the factory, after repeated static and dynamic debugging for many times, there is a one-year warranty period, during this period, any equipment failure caused by non-human responsibility will be responsible by the manufacturer.
In a word, the casting enterprise should choose the most suitable equipment according to the actual needs. In the selection process, the manufacturer should compare the manufacturing, configuration, technical scheme, after-sales service attitude, and other factors before choosing the satisfactory equipment.
Intermediate frequency furnace includes a transformer, air open, harmonic filter, inverter cabinet, water cable, induction coil, furnace housing, and so on. Each family may produce in a different configuration. Because different material, form, price-quality has a difference, had better decide on price respectively. At present, if the furnace is developing towards high power and large capacity, 1 ton IF furnace has been a small, mature technology and relatively cheap price.