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根据小孔壁面上的力学平衡条件,建立了穿孔等离子弧焊(PAW)的小孔模型.利用该模型,对6mm厚不锈钢板PAW准稳态小孔的形成过程进行了数值计算,得到了不同工艺参数下准稳态小孔的形状和尺寸.根据达到准稳态时小孔壁面的受力状态,对PAW过程中小孔从盲孔到穿孔的转变机制进行了探讨,分析计算了小孔壁面上各区域的作用力大小.随着焊接电流的升高,小孔的深度呈现非线性增大;存在一个小孔在熔池内由盲孔突然转变为穿孔状态的焊接电流临界值;等离子弧力在小孔底部急剧集中是导致小孔深度突变的主要原因.通过穿孔PAW焊接工艺实验,对数值计算结果进行了实验验证.
According to the mechanics equilibrium condition on the wall of the orifice, a small hole model of perforation plasma arc welding (PAW) was established.Using this model, the formation process of the quasi-steady pore of PAW in 6mm thick stainless steel was numerically calculated, The shape and size of the quasi-steady-state pinhole under the process parameters are discussed.According to the force state of the pinhole wall when the quasi-steady state is reached, the transition mechanism of the pinhole from the blind hole to the perforation in the PAW process is discussed, the pinhole With the increase of the welding current, the depth of the hole presents a nonlinear increase; there is a critical value of the welding current in which a small hole suddenly changes from a blind hole to a perforated state in the molten pool; and the plasma arc The sharp concentration of force at the bottom of the hole is the main reason leading to the sudden change of the hole depth.According to the experiment of perforated PAW welding process, the numerical calculation results are verified by experiments.