考虑小孔后向偏移的等离子弧焊接热过程模型

发布时间：2019-06-04 18:46

【摘要】：在穿孔等离子弧焊接过程中,背面小孔中心相对于焊枪轴线存在一定的偏移。深入研究小孔孔道后向偏移时所涉及的熔池与小孔瞬态演变行为和传热过程,对于优化以背面小孔中心偏移量为控制参数的控制方法,保证焊缝成形质量具有重要意义和实用价值。针对穿孔等离子弧焊接中小孔的形成特点,建立随小孔形状动态调整的组合式体积热源模型,并在热源模型中引入热源中心向后偏移的参量,间接反映背面小孔后向偏移对穿孔等离子弧焊接热过程的影响。在小孔形状方程中,增加等离子流后推力,间接描述等离子流对熔池流体的后推作用。利用建立的三维瞬态熔池与小孔的数学模型,分析等离子弧焊接过程中温度场和小孔形状的瞬时演变过程。将工件背面小孔形状尺寸和穿孔时间等模拟结果与试验结果进行对比,两者基本吻合,对所建立的数学模型进行验证。
[Abstract]:In the process of piercing plasma arc welding, there is a certain deviation between the center of the back hole and the axis of the welding torch. The transient evolution behavior and heat transfer process of molten pool and small hole involved in backward migration of small hole channel are deeply studied, and the control method with back hole center offset as control parameter is optimized. It is of great significance and practical value to ensure the weld forming quality. According to the formation characteristics of small holes in pierced plasma arc welding, a combined volume heat source model with dynamic adjustment with the shape of holes is established, and the parameters of backward migration of heat source center are introduced into the heat source model. It indirectly reflects the effect of backward deviation of back hole on the thermal process of pierced plasma arc welding. In the pore shape equation, the backward effect of plasma flow on molten pool fluid is described indirectly by adding the thrust after plasma flow. Based on the mathematical model of three-dimensional transient molten pool and small hole, the instantaneous evolution of temperature field and hole shape in plasma arc welding is analyzed. The simulation results, such as the shape, size and perforation time of the small hole on the back of the workpiece, are compared with the experimental results, and the mathematical model is verified.
【作者单位】：山东大学材料液固结构演变与加工教育部重点实验室;
【基金】：国家自然科学基金资助项目(50936003)
【分类号】：TG456.2

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