||This study first, friction stir welding was performed using a variety of welding tools (tungsten carbide, high-speed steel, A6061 aluminum and zinc) for single the ferrite core to explore the feasibility on welding of the ferrite core. The results show that the ferrite core was ruptured due to local heating, its partial rupture temperature about 200 ℃.|
Secondly, in order to prevent rupture of the ferrite core due to local heating, using a heating block for full heating the ferrite core. Welding tool was selected a lower melting point of zinc rod and spot welding experiments of the ferrite core is performed using a method of friction surfacing. Under different operating conditions, such as the normal load (55~118 N), the rotation speed (1800~2550 rpm), the welding time (1~5 minutes), and the 230 ℃ heating temperature of ferrite core surface, the area, surface uniformity and tensile fracture load of coating layer on the surface of ferrite core were investigated.
The results show that the coating layer was not formed under the lighter normal load and lower rotation speed. The coating layer was uniformly formed with increasing the normal load and rotation speed. However, the ferrite core was ruptured when the normal load was larger than 118 N. Increase the normal load rather than the rotation speed could effectively increase the area, surface uniformity and tensile fracture load of coating layer. The region of optimal welding conditions was established according the experimental results.
Finally, according to the experimental results of a spot welding, an entity operating conditions was selected so that its surface coating is uniform with better tensile failure load to weld the transformer successfully.