电极导热系数对电触头组件焊接质量的影响

Influence of Thermal Conductivity on Brazing Quality of Electrical Contact Components

本文提出了电触点电阻钎焊的电热耦合有限元模型,数值分析了电极导热系数对电触点电阻钎焊焊接质量的影响。结果表明:当紫铜电极导热系数增大倍数而不超过5倍时,紫铜上部电极尖端的温度降低,这样就可减少紫铜电极的软化,减少上部紫铜电极与工件之间的粘附,减少上电极尖端的变形,从而减少了虚焊的发生,又不会对电触点的钎焊质量造成影响。当紫铜电极导热系数增大幅度超过这一范围时,焊接面温度分布明显变得不均衡,电触头焊接质量也会大大降低,且焊接时间是原来的1倍以上,大大降低了电阻钎焊的加工效率。这说明,导热系数相对高些的电极有助于降低电极与待焊工件之间粘连、电触头组件虚焊的概率,因此,我们可通过调整电极导热系数来提高电触头组件的焊接质量。

A thermoelectric FEM model was proposed to analyze the influence of thermal conductivity of electrode on brazing quality of electrical contact components during the resistance brazing process. The numerical results show that when the increasing magnitude of thermal conductivity of copper electrode is 1-5 times than that of the original,the temperature at the electrode tip of the upper copper reduces, resulting in less sottening of copper electrode, less adhesion between the upper copper electrode and the workpiece, and less deformation of electrode tip. Thus the occurence of dry joint reduces, and it has no influence on brazing quality of electrical contact. When the thermal conductivity of copper electrode increases over this range, the temperature distribution of brazing surface become obviously ununiform and it causes poor brazing quality of electrical contact. In addition, the brazing time is 1 times higher than the original. And the production efficiency slows down quickly. This indicates that the electrode with relatively higher conductivity is beneficial to decrease the probability of adhesion and dry joint between electrode. Therefore, the brazing quality of electrical contact components can be improved by adjusting thermal conductivity of electrode.