Study on the magnetic-thermal evolution and air cooling synergy of bevel gears: based on asynchronous multi-frequency electromagnetic heating

Abstract

This study proposes an asynchronous multi-frequency heating (TFH) method combined with air-cooling control, revealing the magneto-thermal evolution law in spiral bevel gear heating. Research demonstrates that TFH achieves pulsed thermal excitation on gear surfaces through time-domain modulation of electromagnetic parameters, while the heat flux penetration depth (d) exhibits asymmetric characteristics on bilateral tooth surfaces. A Gaussian eddy-current model incorporating an attenuation term demonstrates that this asymmetry arises from localized eddy-current concentration difference dictated by sharp corner effect driven by tangential edge angle (α). Discrepancies of α at the gear's large end cause 76.3 % greater d on the concave side (smaller α) versus the convex side. Conversely, gradual tooth-profile variations at the small end invert this trend, yielding 85.1 % deeper heating on the convex side. Investigations reveal gradient-distributed air-cooling rates at tooth tip, middle, and bottom sections during frequency switching, with this dynamic thermal dissipation behavior effectively compensating temperature differentials induced by gradual tooth-profile variations. The bi-directional dispersion degree of the tooth surface temperature (S), as a temperature uniformity metric, demonstrates a 60 % reduction when using TFH compared to single-frequency methods, indicating the significant advantage of this strategy in achieving uniform heating for complex workpieces.