Experimental and numerical study of the effect of coil structure on induction nitriding temperature field

Kangjie Song,Kunmao Li,Jing Liu,Jing Guan

doi:10.1177/1687814020938484

Kangjie Song, Kunmao Li + Show 2 more

Open Access

https://doi.org/10.1177/1687814020938484

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Abstract

The axial and radial temperature distributions of an induction heating workpiece considerably impact the subsequent nitriding process. To obtain a satisfactory temperature distribution, an equal pitch coil, a variable pitch coil, and a variable radius coil were designed. Furthermore, an induction heating model that exhibits electromagnetic and temperature field coupling was established; thus, the effects of the current density and frequency on the heating efficiency and temperature distribution of the workpiece were analyzed and compared. In addition, an induction heating experiment was conducted to verify the model. According to the numerical results, the variable radius coil can reduce the axial temperature difference in comparison with equal pitch coil and variable pitch coil. Hence, the workpiece heated using the variable radius coil can achieve a better temperature distribution when compared with those heated by the equal pitch coil and variable pitch coil, with appropriate current density and current frequency values.

Highlights

The induction nitridation process[1,2] is an efficient method for surface treatment of the magnetic metal material.[3,4] Its unique heating technology is widely used in the surface treatment of metal materials[5] and welding.[6]
Considering the major influence of the induction heating coil shape on the temperature distribution of the workpiece, this study investigates the effects of equal pitch coil (EPC), variable pitch coil (VPC), and variable radius coil (VRC) on the temperature distribution of the workpiece
Based on the comparison of the axial and radial temperature differences among the three coils, when the current frequency of the VRC is increased from 10 to 30 kHz, the axial temperature difference decreases from 27.67 °C to 7.14 °C, which is a reduction of 74.2 %

Summary

Introduction

The induction nitridation process[1,2] is an efficient method for surface treatment of the magnetic metal material.[3,4] Its unique heating technology is widely used in the surface treatment of metal materials[5] and welding.[6]. Han et al.[29] established a threedimensional induction heating model They performed numerical analysis on the current frequency and the distance between the coil and the weld, by varying the current density. A better temperature distribution can be obtained using experimental and numerical simulations of the workpiece heated by the longitudinal coil, considering the influence of the coil shape on the temperature distribution These studies have focused on coil heating parameters and the radial temperature difference of the workpiece. The electromagnetic field and distribution of magnetic flux density can be calculated by introducing the model and determining the relative position of the workpiece to the coil. The update includes temperature-dependent material constants for relative permeability, resistivity, thermal conductivity, and specific heat, and the program proceeds to the time step. Once the temperature analysis required for heating is finished, the program ends

Findings

Result and discussion

Conclusion