Research On The Numerical Simulation Of Electromagnetic-Thermal Coupling Field Of Strip Steel In Induction Heating

Induction heating uses the joule heating effect of eddy currents to heat the work piece. This heating method has characteristics such as high efficiency, precise control and less pollution. But the temperature difference between the center and surface is too large, which leads to additional stress and uneven organization in the work piece and even causes forming cracks to impact the quality and forming process of the materials. It is convinced that precisely controlling the input power and heating time and optimizing structure and operation parameters of the equipment, on the basis of satisfying the performance requirements of heating work piece, can effectively improve the quality of products, heating efficiency and save resources.In this paper, the process of strip steel work piece induction heating magnetic-thermal coupling field numerical simulation was achieved based on the principle of induction heating. An actual strip induction heating process was simulated through the coupling calculation of finite element software ANSYS.First of all, the establishment of a strip steel coupling field mathematical model of induction heating problems was determined. On obtaining the movement of work piece in the process of induction heating, grid nodes and serial number were kept constant, coupling calculation was made after coil model moved each time and each node respectively was treated as the initial conditions of the next simulation, at last the results of this coil relative movement was considered the strip movement.Second, the effect of the magnetic flux device was verified to improving induction heating efficiency by using the established model using the established model. The relationship among the joule heat, magnetic field and temperature field distribution was studied when the air gap changed. Even though the moving speed of strip had nothing to do with the temperature increasing rate while other parameters remaining unchanged, but the speed could influence the highest temperature reaching time and the maximum of temperature. Under the condition of constant current density, increasing the frequency could improve the intensity of magnetic field and the temperature increasing rate and shorten the heating time, but the depth of the eddy current induction decreased and temperature gradually increased. Under the condition of same frequencies, the increase of current density would cause temperature increasing rate increased, heating time decreased and temperature difference between the upper and lower surfaces increased, but it had little effect on induced eddy current penetration depth.Finally, multiple simulation results were analyzed through the application of Design Expert 8.0 software, the best parameter is current density 1.50×106A/m2、the frequency 250Hz and the air gap 3mm.