永磁体作用下电阻点焊熔核中的电磁场分布规律

Magnetic Field Distribution in Resistance Spot Welding Nugget under Permanent Magnet

采用数值模拟方法研究了外加永磁体磁场作用下,电阻点焊熔核内的外部磁场、感应磁场及复合磁场强度及其磁场力的分布规律,并对熔化金属的流体流动模式进行了定性分析.结果表明,在外加磁场作用下,点焊熔核内的复合磁场分布以感应磁场为主导,从熔核中心至边缘逐渐增强,其径向磁感应强度分量随着永磁体工作距离增加而逐渐减小.熔核内同时存在由感应磁场生成的位于电极轴对称平面内的磁场力,以及由外加磁场引起的垂直于该平面的磁场力.在该正交磁场力的作用下,熔核内的熔化金属在电极轴对称平面及垂直于该平面的圆周方向同时进行高速流动,并呈现出沿熔核直径方向向外冲击的趋势.

Distributions of magnetic field,both external and induced,in nugget region of resistance spot welding（RSW） under permanent magnets were investigated using numerical simulation method.Based on the complex magnetic force distribution,the fluid flow behavior in RSW was systematically analyzed.The results show that the induced magnetic field predominates in RSW process under the permanent magnets. The complex magnetic flux density gradually increases from the center to the edge of the weld nugget,while the radial magnetic flux density gradually decreases with the increasing working distance of permanent magnets.Two perpendicular magnetic component forces exist in the nugget.One acts in the axisymmetric plane of the electrodes generated by the induced magnetic field,the other acts vertically to the plane generated by the external magnetic field.Driven by the complex magnetic force,the molten metal in the nugget would flow with high velocity in both the axisymmetric plane of the electrodes and the circumferential direction perpendicular to the plane.