Overview
The eddy currents generated by high-frequency varying magnetic fields are uneven in the tooth surface, so the material properties change a great deal as the temperature rises. In order to handle the detailed phenomena, it is necessary to calculate the heat generation amount in a numerical analysis based on the finite element method (FEM).
In this material, the validity of coil geometry used for quenching is evaluated by heating the gear top and bottom at high and low frequencies, respectively, to confirm uniform temperature distribution on the surface of the gear.
Eddy Current Loss Density Distribution of the Gear
It’s also possible to confirm the changes in the eddy currents due to different frequencies. Eddy currents are distributed on the gear bottom at low frequency and on the gear surface and tip at high frequency due to the skin effect.
Temperature Distribution and Variation of the Gear
Temperature distribution in the gears is shown in Fig. 2. Fig. 3 shows the time characteristics of temperature variations at each temperature measurement point. From the temperature distribution, it is apparent that the eddy currents generate heat in the tooth top.
The difference in heat generation from the coil geometry can also be verified in Fig. 3. It is also possible to confirm at each measurement point that the temperature exceeds the Curie point of 800 deg C at around 2.0 sec.