The practical application of induction heating technology in construction machinery

Induction heating is a method that uses electromagnetic induction to generate an electric current inside the material to be heated (i.e., the workpiece), and relies on the energy of these eddy currents to achieve the heating purpose. The basic components of an induction heating system include an induction coil, an AC power supply and a workpiece. Depending on the object being heated, the coil can be made into different shapes.

The coil is connected to the power supply. The power supply provides alternating current to the coil. The alternating current flowing through the coil generates an alternating magnetic field passing through the workpiece. This magnetic field causes eddy currents in the workpiece to heat it up. Induction heating began along with the birth of the automotive and tractor industries. Due to its advantages such as high heating efficiency, fast speed, good controllability, and easy realization of mechanization and automation.

The most commonly used and effective heat treatment processes at present have the following multiple applications: surface hardening, through heating quenching, tempering and stress relief (low temperature), annealing and normalizing (high temperature), weld seam annealing, powder metal sintering, etc. It has been widely applied in industries such as smelting, casting, pipe bending, hot forging, welding and surface heat treatment. In the field of casting, the double-melting process is developing rapidly, that is, using medium-frequency furnaces for heat preservation and modification to conduct precise casting of ductile iron or alloy steel. In terms of forging, the use of bold heating to achieve rapid through heating hot forging not only reduces the loss of oxide scale but also significantly increases the service life of the forging die. Its material utilization rate can reach 85%, and the surface roughness of the forged part can be less than 50μm. In terms of welding and quenching, foreign countries are committed to developing high-power all-solid-state high-frequency power supplies on the one hand, and highly automated complete sets of heat treatment processing systems on the other. At present, China requires approximately 10 million tons of castings annually. However, the foundry industry still mainly relies on cupola furnace smelting and general cast iron casting, with relatively small tonnage. This leads to significant fluctuations in temperature and composition, as well as a high scrap rate. The scrap rate of a better foundry industry is also between 6 and 15, while that of a general foundry can be as high as 30.