Induction Heating During Hardening of the Balls Bearings

Hardening is widely used in production of various workpieces like balls for ball bearings. Processes of spheres heat treatment are in attention focus because of mass production. High requirements to profitability, accuracy, and repeatability are imposed to these processes. Classical technologies of gas and electric heating do not meet these requirements because intensities of heating are small and therefore internal parts of spheres become also warm. So, induction heating misplaces traditional heating technologies in this process. Typical designs of inductors are unsuitable as they do not provide the required uniformity of heating for hardening. However, technologies of induction heating need to be adapted for heat treatment of spherical workpieces. In this article a new design of the inductor for spheres hardening is proposed. It allows obtaining uniform distribution of temperature on the surface of heated sphere. To investigate the proposed design, the numerical model of installation has been developed in the Cedrat FLUX v 10.4 software package. The uniform temperature distribution on a sphere surface is obtained. Temperature difference on the surface of the sphere is 30°C which meets requirements to the hardening process. The internal part of sphere is not heated up because of the high speed of heating in the inductor. It allows increasing heating efficiency as there is no energy consumption for heating within sphere's core Also, the combination of high skin hardness and the viscoelastic middle is reached. It raises durability of the ball bearing and its reliability. The aim of the article is to show the approach to geometrical design of inductor to achieve uniform surface temperature distribution for the heated ball. Numerical modeling is carried out for the analysis of the design proposed.