变堆积位姿下低功率激光辅助P-GMAW增材制造熔池流动行为及成形控制研究

According to problems of low forming capacity of inclined plane and poor formation quality of complex thin-walled parts fabricated in GMAW additive manufacturing, a technology of laser-assisted P-GMAW additive manufacturing with variable deposition pose is proposed in this project. Arc drift or interruption is avoided in multi-deposition process based on the laser stabilizing arc effect, and the forming quality is improved. The formation of an arbitrary inclination is realized under variable deposition pose. This project takes molten pool flow behavior as point of penetration, and aims at improving the formation quality control. The evolvement of molten pool flow behavior in multi-deposition process with flat deposition pose is studied by the means of experiments and numerical simulation. By analysis of thermal and force effect in the molten pool, the formation collapse mechanism is clarified. Further, the depence of the molten pool behavior on process parameters in terms of deposition path, heat input, direction, etc. will be investigated under varibale deposition pose. The mechanism and key control factor of molten pool stability are revealed. By establishing the three-dimensional evaluation model for surface quality, relationships between forming quality and deposition pose, parameters, inter-layer temperature, are disclosed. Control strategy of formation is proposed. By the research of this project, the theoretical knowledge of low power laser-assisted P-GMAW additive manufacturing is enriched. At the meantime, it can provide a valuable scientific method and a technique solution lay for fabricating thin-walled parts with high-quality and arbitrary-inclination.

针对复杂薄壁件GMAW增材制造成形质量差和倾斜面成形能力低的问题，本项目提出变堆积位姿下低功率激光辅助P-GMAW增材制造技术。利用激光稳弧作用，避免多重堆积下电弧漂移或断弧，有效提高成形质量；变堆积位姿实现任意倾角成形。项目以成形熔池流动行为研究为切入点，解决任意倾角薄壁件成形控制难题。采用实验和数值模拟相结合的手段研究平堆位姿下多重堆积熔池流动行为演变规律，分析熔池的热、力作用机制，明晰多层单道成形易出现坍塌的机制；探究变堆积位姿下过程参数（堆积路径、堆积方向、堆积热输入等）对熔池流动行为的影响规律，阐明熔池稳定性的主控因素及其控制机理；建立多重堆积成形表面质量三维评价模型，明确成形质量与堆积位姿、工艺参数及层间温度的关系，提出成形控制策略。本项目的研究，一方面丰富低功率激光辅助P-GMAW增材制造理论；另一方面可望为任意倾角薄壁件的高质量成形提供有价值的科学方法和技术实现途径。

针对复杂薄壁件GMAW增材制造成形质量差和倾斜面成形能力低的问题，本项目提出变堆积位姿下低功率激光辅助P-GMAW增材制造技术。利用激光稳弧作用，避免多重堆积下电弧漂移或断弧，有效提高成形质量；变堆积位姿实现任意倾角成形。主要研究了多重堆积过程热特性及熔池行为、表面质量评价及影响因素、倾斜薄壁件成形质量控制。结果表明：多重堆积过程热积累较为严重，熔池散热主要沿堆积高度方向，且与前一层堆积路径密切相关。增加基板厚度或层间等待时间可改善前几层熔池散热状况，基板形状与堆积路径的匹配关系对熔池散热影响较大；堆积电流对多重堆积熔池流动行为的影响最为显著，随堆积电流增大，熔池下凹明显且流速增加，液态金属向熔池后方运动幅度增大；变堆积位姿态下，与焊枪倾角成锐角的基板侧散热能力更强。减小焊枪与堆积路径方向夹角，可提高堆积层熔池稳定性；建立了基于激光视觉三维恢复的多重堆积表面质量评价模型，低功率激光辅助可以提高堆积层表面质量。层间温度增加，表面质量下降，而小电流匹配低行走速度有助于提高堆积层表面质量；焊枪横向偏移方式成形倾斜面的能力不足，而横堆位姿下采用小电流可成形堆积层生长方向与基板平面垂直的薄壁件。.本项目提供了一种变堆积位姿下低功率激光辅助P-GMAW增材制造新思路，实现了任意倾角薄壁件的高质量成形，具有良好的工程化应用前景。项目培养硕士生2名，本科生8名，发表论文14篇，其中SCI期刊论文11篇，EI论文3篇，申请发明专利18项，已授权5项。