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高强铝合金CMT+P电弧增材制造熔滴过渡行为研究

张志强1,勾青泽1,路学成1,王浩2,曹轶然1,郭志永1   

  1. 1. 中国民航大学
    2. 天津职业技术师范大学
  • 收稿日期:2022-08-01 修回日期:2022-09-09 出版日期:2022-09-22 发布日期:2022-09-22
  • 通讯作者: 王浩
  • 基金资助:
    国家自然科学基金;航空科学基金;天津市教委教研计划项目;天津市科技计划项目

Study on droplet transfer behavior of high strength aluminum alloy cmt+p arc additive manufacturing

  • Received:2022-08-01 Revised:2022-09-09 Online:2022-09-22 Published:2022-09-22
  • Supported by:
    National Natural Science Foundation of China;Aeronautical Science Foundation of China;Scientific Research Project of Tianjin Education Commission;Science and Technology program of Tianjin

摘要: 新型冷金属过渡与脉冲(CMT+P)复合电弧技术实现了对电弧能量的精细控制,为获得高质量电弧增材成形件提供了可靠保证。然而,CMT与脉冲协同作用过程中的熔滴过渡行为尚不清晰,其对增材过程稳定性、成形质量有重要影响。本文以高强铝合金为研究对象,基于流体力学和电磁学理论,采用动网格与界面追踪技术,综合运用数值模拟和原位观测试验手段,研究了高强铝合金CMT+P电弧增材过程中的熔滴过渡行为。结果表明,模拟结果与试验结果高度吻合;平均送丝速度5 m/s时,高强铝合金CMT+P电弧增材工艺的熔滴过渡呈现CMT阶段的短路过渡和脉冲阶段的一脉一滴射滴过渡的混合过渡模式;在短路阶段由熔丝机械拉力形成的金属液桥可有效避免熔滴飞溅,提高成形质量;在脉冲阶段熔滴受到电磁力、表面张力、Marangoni力、重力和等离子流力耦合作用内部形成静止区,速度在静止区收敛或者发散,呈现流速上下反向的特点,进而影响熔滴过渡的稳定性。

关键词: 冷金属过渡加脉冲, 电弧增材制造, 熔滴过渡, 流场, 数值模拟

Abstract: The new technology of cold metal transition and pulse (CMT+P) composite arc realizes the fine control of arc energy, and provides a reliable guarantee for obtaining high-quality arc additive formed parts. However, the droplet transfer behavior in the synergistic action of CMT and pulse is not clear, which has an important impact on the stability of additive process and forming quality. Based on the theory of hydrodynamics and electromagnetism, this paper takes high-strength aluminum alloy as the research object, adopts dynamic grid technology and interface tracking technology, and comprehensively uses numerical simulation and in-situ observation test methods to clarify the evolution mechanism of droplet transfer behavior in the process of CMT+P arc additive of high-strength aluminum alloy. The results show that the simulation results are highly consistent with the experimental results. When the average wire feeding speed is 5 m/s, the droplet transfer of high-strength aluminum alloy CMT+P arc additive process presents a mixed transition mode of short-circuit transition in CMT stage and one pulse one drop ejection transition in pulse stage. The metal liquid bridge formed by the mechanical tension of the fuse in the short circuit stage can effectively avoid the splashing of molten droplets and improve the forming quality. In the pulse stage, the droplet is coupled by electromagnetic force, surface tension, Marangoni force, gravity and plasma flow force to form a static area. The velocity converges or diverges in the static area, forming the characteristics of upward and downward reverse flow velocity, which further affects the stability of droplet transition.

Key words: Cold Metal Transfer Plus Pulse, Arc Additive Manufacturing, Droplet Transfer, Flow Field, Numerical Simulation

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