金属薄材超声波点焊的研究进展

Research progress in ultrasonic spot welding of metal sheet

详细讨论了金属薄材超声波点焊接头的界面温度、宏观特征、微观组织、力学性能、工艺优化、力学性能强化措施及焊接机理。分析了目前研究中存在的问题,指出焊接界面应力应变场、塑性变形过程和塑性变形机制的研究需深入研究。影响超声波点焊质量的因素分为两类:工艺参数和材料属性。工艺参数包含焊接压力、振幅、焊接时间/焊接能量、功率、焊头和底座表面尖齿的尺寸及形状等。材料属性主要包括材料的类别、硬度、表面粗糙度、氧化情况等。工艺参数和材料之间的良好耦合才能获得最佳的焊接工艺条件。此外,焊接界面的焊合密度和焊后接头有效厚度是决定超声波点焊接头力学性能的两个主要因素,两因素之间存在着矛盾的关系,如何化解这对矛盾关系是提高接头力学性能的关键所在。

The current states of joining metal sheets by ultrasonic spot welding with numerous critical issues,such as interfacial temperature,macrostructure,microstructure,mechanical properties,general process parameter optimization,strengthening method of mechanical properties and joining mechanism were systematically summarized.The current problems were analyzed,and it was noted that the stress and strain field of welding interface,the process and mechanism of plastic deformation should be investigated in further.Influences on the quality of ultrasonic spot welded joints were processing parameters and materials properties.Processing parameters were composed of clamping force,amplitude,welding time/welding energy,power,dimensions and shape of the knurl pattern of the anvil and sonotrode tip,and so on.Materials properties included materials categories,hardness,surface roughness,degree of oxidation,and so on.The best welding process conditions could be obtained only by good coupling between process parameters and materials can.In addition,bond density and post-welded thickness were two key factors to the mechanical strength of ultrasonic spot welded joints,but a contradictory relation existed between the two key factors,how to resolve the contradictory relation was critical to enhance the joint strength.