Study on Improvement of Axial Temperature Uniformity of Large Aluminum Billets Heated by 1-MW HTS DC Induction Heater

The temperature at the end of the aluminum billet with a large radius is higher than that in the middle at the end of heating even the aluminum billet is heated by rotating with low velocity, which makes the aluminum billet have a risk of local melting and is bad for the quality of the product. In order to improve the axial temperature uniformity and avoid local melting, a new method based on a 1MW HTS DC induction heater has been proposed. In the method, the regulation of the magnetic flux density distribution in the heating area can be achieved by adding different barrel-shaped ferromagnetic blocks around the aluminum billet, and the resultant adjustment of the temperature distribution of the aluminum billet has also been investigated. The results show that the magnetic field is strengthened in the aluminum billet area covered by the ferromagnetic block and weakened in the remaining aluminum billet area, which is good for solving the overheating problem at the aluminum billet ends during the heating process. The magnetic flux density distribution in the heating area can be adjusted by changing the cross-sectional shape and the size of the ferromagnetic block. And the desired axial temperature uniformity of the aluminum billet can be obtained by using an appropriate ferromagnetic block. What is more, the heating time taken to heat the aluminum billet to a given temperature is shorter with a proper ferromagnetic block than without it, and the risk of local overheating can also be avoided.