Explain Coreless Type Induction Furnace

 

A coreless type induction furnace is a metallurgical device operating on the principle of electromagnetic induction. Its main characteristic is the absence of a closed iron core structure within the induction coil. It consists of a furnace frame, an induction coil wound with shaped copper tubing, and a crucible made of a special material.

This design reduces capital and installation costs and increases the flexibility of alloy selection.

Coreless induction furnaces also feature safety features such as anti-vibration structures, a leak detection alarm system, a parallel coil structure, and a high-efficiency IGBT inverter power supply, all ensuring efficient and safe operation.

Structural Features of Coreless Type Induction Furnace

• The furnace body employs a layered design. The induction coil is constructed from shaped copper tubing with varying wall thicknesses (10-15mm inner wall/2-4mm outer wall), and the electromagnetic field strength is enhanced by parallel silicon steel sheet iron pillars.
• The crucible material is selected based on the molten metal: magnesia (basic), silica sand (acidic), alumina (neutral), or precast graphite. The economical capacity threshold is 750 kg of steel/cast iron.
• Compensation capacitor banks account for 25-30% of equipment costs and require dedicated cooling devices to prevent overheating failure.

Power System of IF Furnace

• The industrial frequency furnace is directly connected to the three-phase power grid.
• Single-phase load balancing is achieved through balancing capacitors, and the voltage regulating transformer allows for precise control of input power.
• Coreless induction melting furnaces, as a type of induction furnace where no iron core passes through the inductor, consist of a furnace frame, an induction coil wound with copper tubing, and a crucible.
• Medium frequency furnaces use thyristor inverters or generator sets, covering a frequency range of 500-8000Hz, suitable for capacities from 20 kg to 20 tons. 
• High frequency furnaces (>20kHz) are limited by the skin effect and are mainly used for small-capacity melting in laboratories (≤50 kg steel).

Coreless Induction Furnace Melting Process

Coreless type induction furnace employ electromagnetic stirring technology. The stirring intensity is controlled by optimizing the segmented power supply strategy for the coils. The overall stirring mode can solve the segregation problem caused by differences in the specific gravity of alloying elements.

Industrial frequency furnaces require a starting block of 200mm or larger to start.

Compared to cupola furnaces, they reduce coke contamination during cast iron smelting, and the carbon content fluctuation in molten iron can be controlled within ±0.05%. The 10-ton class equipment is equipped with a hydraulic tilting system and a cooling water circulation device (water temperature ≤35℃) to extend coil life.

For any questions or needs regarding induction melting furnaces such as medium frequency furnaces, industrial frequency furnaces, cored induction furnaces, and coreless induction furnaces, please feel free to contact us for one-stop service.

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Xi'an Sanrui Electric Furnace