穿孔法等离子弧立焊焊缝成形机理初探

通过对立焊穿孔熔池的受力状态的分析,初步揭示了穿孔法等离子弧立焊焊缝成形机理,从而发现焊接工艺参数对焊缝成形影响的规律,为进一步研究穿孔法等离子弧立焊焊缝成形机理奠定了基础理论分析和试验结果均表明,穿孔能否连续稳定存在是焊缝成形的前提,而穿孔熔池液面金属的受力及流动则对焊缝正反面的成形起着重要作用在此基础上指出,焊接电流和离子气流量过大时会因穿孔熔池下半部的收缩能力小于上半部的扩张速度而形成切割,反之,过小的焊接电流和离子气流量会形成未焊透控制焊接电流的大小和喷嘴到工件的距离均可有效地实现对焊缝正反面增高量及宽度的控制

A Preliminary Study on the Weld Formation of Keyhole Plasma Welding in Vertical Position

Force analyses of the liquid metal in the keyhole pool are made to formulate preliminarily the weld formation in keyhole mode vertical position PAW and to find out the influences of welding conditions on the weld formation.The findings lay a foundation for further research into the weld formation in the keyhole mode vertical position PAW . The test result shows that whether the keyhole exists steadily in a workpiece throughout the welding is the premise of the weld formation and that the flow of the liquid metal in the keyhole pool is of great importance to the weld formation on the front and the back sides . Based on the above analysis and experimental result,it is pointed out that if the welding current and the flow rate of plasma are too high, a cutting is formed, for the contraction rate of the lower pool is lower than the expansion rate of the upper pool,but if the welding current and the flow rate are too low, the workpiece is not penetrated . The high crowns and widths of the weld on the front and back sides are controlled by adjusting the current and the distance from the nozzle to the workpiece.