超声等离子焊接在液压支架修复工艺中的应用

为提升液压支架修复的可靠性和经济性，对超声等离子焊接的应用效果进行了数值模拟和试验研究。根据所设计超声等离子弧焊系统的焊枪结构与焊接工艺参数建立了超声场有限元模型，基于COMSOL求解等离子气体的速度场、电弧密度场和声压场。对修复后的液压支架试样进行了显微硬度、残余应力及冲击韧性等力学性能测试。结果表明，超声波可在同等条件下将电弧压力提升20%以上，并在4 mm电弧直径内显著增强电流密度，有效减小热影响区范围和残余应力；等离子气体流速与电弧密度在靠近支架焊缝区域以近似相反的变化趋势分布，二阶特征频率振源能够在电极附近产生驻波；修复后支架的平均硬度和室温冲击吸收能量相比母材分别提升了44.6%和45.8%。

Application of ultrasonic plasma arc welding in repair process of hydraulic support

Abstract: In order to improve the reliability and economy of repair process of hydraulic support, the application effect of ultrasonic plasma arc welding was numerically simulated and experimentally studied.According to welding gun structure and welding parameters of the designed ultrasonic plasma arc welding system, the finite element model of ultrasonic field was established, and the velocity field, arc density field and sound pressure field of plasma gas were solved based on COMSOL.The microhardness, residual stress and impact toughness of the repaired hydraulic support samples were tested.The results showed that ultrasonic could increase the arc pressure by more than 20% under the same conditions, significantly enhance the current density within 4 mm arc diameter, and effectively reduce the range of heat affected zone and residual stress.The plasma gas velocity and arc density appeared an approximately opposite trend in the area near the support weld, and the second-order characteristic frequency vibration source could produce a standing wave near the electrode.Compared with the base metal, the average hardness and room temperature impact energy of the repaired support welds increased by 45% and 45.8% respectively. Highlights:(1)According to the structural characteristics of the ultrasonic plasma arc welding system, the matching finite element model of ultrasonic field was established.The velocity field, arc density field and acoustic pressure field of plasma gas in the model were solved based on COMSOL. (2)In order to verify the improvement effect of ultrasonic on comprehensive mechanical properties, mechanical properties of repaired specimens were tested and analyzed, including microhardness, residual stress and impact toughness.