K-PAW准稳态过程小孔与熔池动态行为的数值模拟

发布时间：2018-03-20 02:25

  本文选题：K-PAW准稳态过程　切入点：小孔　出处：《金属学报》2016年07期 　论文类型：期刊论文

【摘要】：基于流体动力学原理,同时考虑电弧压力、表面张力、电磁收缩力、浮力和重力等因素影响,建立了随小孔深度增加热力作用二次变化的三维瞬态计算模型.利用上部双椭球体下部锥体的组合式体积热源描述等离子电弧对焊接工件的热作用,提出了可以维持小孔稳定的"孔内固体搅动式"计算方法.为了提高计算效率,建立了相对焊缝纵截面对称的计算区域;计算过程利用流体体积函数(VOF)法追踪小孔边界,基于FLUENT软件对穿孔型等离子弧准稳态焊接过程进行了数值模拟,得到了准稳态焊接过程中小孔、熔池及流场的动态变化行为,分析了穿孔型等离子弧焊接(K-PAW)准稳态过程的稳定性,探讨了影响小孔稳定的工艺因素,最后进行了计算模型的验证实验.结果表明,在设定的焊接工艺参数下,3.0 s之后焊接过程达到准稳态,准稳态焊接过程中小孔前壁熔池较薄,平均厚度为0.6 mm,且小孔前壁有一定倾斜现象,使得背面小孔中心相对焊接中心向后偏移,焊接不同时刻偏移量在0.46~0.97 mm之间波动.在准稳态焊接过程中熔池内存在稳定的逆时针涡流,计算所得的背面小孔宽度与实验结果吻合良好.
[Abstract]:Based on the principle of hydrodynamics and considering the influence of arc pressure, surface tension, electromagnetic contraction force, buoyancy and gravity, etc. A three-dimensional transient model is established for the secondary variation of thermal action with the increase of hole depth. The combined volumetric heat source of the upper double ellipsoid and lower cone is used to describe the thermal effect of plasma arc on the welded workpiece. In order to improve the calculation efficiency, a symmetrical calculation area relative to the longitudinal section of the weld is established, and the fluid volume function (VOF) method is used to trace the pore boundary during the calculation. Based on FLUENT software, the numerical simulation of the quasi-steady welding process of perforated plasma arc is carried out, and the dynamic behavior of small holes, molten pool and flow field in the process of quasi-steady welding is obtained. The stability of K-PAW quasi-steady process in perforated plasma arc welding is analyzed, and the technological factors affecting the stability of the keyhole are discussed. Finally, the verification experiment of the calculation model is carried out. The results show that, The welding process reaches quasi-steady state after 3.0 s under the set welding process parameters. In the process of quasi-steady welding, the weld pool of the front wall of the small hole is thin, the average thickness is 0.6 mm, and the front wall of the small hole is inclined to a certain extent. The center of the back hole moves backward relative to the center of the welding, and the deviation at different times fluctuates between 0.46 mm and 0.97 mm. There is a steady counterclockwise eddy current in the molten pool during the quasi-steady welding process. The calculated width of the back hole is in good agreement with the experimental results.
【作者单位】： 北京工业大学机械工程与应用电子技术学院汽车结构部件先进制造技术教育部工程研究中心;江苏科技大学江苏省先进焊接技术重点实验室;
【基金】：国家自然科学基金资助项目51205176~~
【分类号】：TG456.2
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本文编号：1637105