梯度功能材料多丝多旁路等离子弧增材制造的热流输送机制与成形控制

Focus on the requirements of the Functionally Gradient Materials (FGM) design and the Material Structure function integrated manufacturing for track of electromagnetic railgun, the multi-wire and multi-bypass plasma arc additive manufacturing is proposed. By controlling the current and filling wire in each bypass, the energy in each bypass and the workpiece could be adjusted dynamic and real-time, which achieve the control of heat, mass and pressure transfer in both fill wire and workpiece. Combine with the characteristic of energy allocation in bypass plasma arc, this project is focus on the influence mechanism of heterogeneous droplet and component gradient on the whole process of additive manufacturing, the non-equilibrium melting model of heterogeneous filling wire will be constructed. The energy - quality - momentum associated matching mechanism among heterogeneous drops will be analyzed to achieve the independent state control of each bypass droplet. The fusion and expansion behaviors of heterogeneous droplet and weakly confined molten pool will be studied, the multiphase-flow model of molten pool could be established to analyze the influence mechanism of component gradient on molten pool flow and solidification process. The correlation mechanism between input parameters and molten pool behavior and the expression form of molten pool characteristics will be revealed. Based on the target component distribution and structure design of FGM, the influence mechanism of component gradient on stress distribution under multiple thermal cycles will be studied, and the correlation model of input parameters, process characteristics and stress distribution will be constructed. The dynamic compensation and optimization strategy of multi-wire and multi-bypass plasma arc input parameters could be obtained, which lays a foundation for the realization of gradient material arc additive manufacturing.

针对电磁轨道构件的梯度功能设计与材料结构功能一体化制造需求，提出多丝多旁路等离子弧增材制造技术，通过各旁路电流/送丝独立调控，对各旁路与基体间能量的进行动态分配和实时调整，实现异质丝材与基体的热质力传输解耦控制。项目结合旁路等离子弧热源能量分配特性，针对异质熔滴及成分梯度对增材全过程的影响机理开展研究，构建异质丝材的非均衡熔化模型，揭示异质熔滴的能量-质量-动量关联与匹配机制，实现各旁路熔滴的独立物态控制；研究异质熔滴与弱拘束熔池的熔合和扩展行为，建立熔池多相流模型分析成分梯度对熔池流动与凝固过程的影响机理，揭示输入参量与熔池行为的关联机制和熔池特征的表达形式；根据梯度增材构件的目标组分分布与结构设计，研究多重热循环下成分梯度对应力分布的影响机制，建立输入参量、过程特征与应力应变分布的关联模型，得出多丝多旁路等离子弧输入参量动态补偿和优化策略，为实现梯度材料电弧增材制造奠定基础。

自2020年项目启动以来，围绕“双旁路等离子弧热质传输机制及工艺特性”的主题，依次从旁路等离子弧热质传输特性、双旁路等离子弧能量传输机理、异质双丝旁路等离子弧沉积成形控制等方面展开研究工作，解决的关键问题和创新性研究成果概述如下：基于建立的传热模型，研究了旁路等离子弧中工艺参数对作用于丝材总能量的影响规律，探明了丝材端的传热机制，研究了工艺参数对丝材熔化能力的影响规律，进一步揭示了旁路等离子弧中热质解耦机理；建立了双旁路等离子弧电弧模型，分析了电流匹配组合模式等参数对温度场、速度场及双丝材端和基板端的能量分布等特性的影响规律，揭示了双旁路等离子弧热力传输机制及双丝材及基板间的能量匹配机制；提出了脉冲旁路等离子弧焊接制造工艺，研究了单路电流脉冲调制时各参数对熔滴过渡行为的影响规律，进一步实现了热质力灵活控制；研究了多工艺参数对熔覆层成形的影响规律，揭示了热质力传输对熔覆层成形的调控机制，建立了异质双丝双旁路等离子弧增材制造试验系统，以熔覆层成形、温度分布等特征量为评价指标，研究了电流匹配方式对熔覆层成形的影响规律，为双旁路等离子增材制造技术在梯度材料增材制备领域的应用奠定了基础。总结研究结果，已发表论文4篇，其中国际期刊论文（SCI）2篇，会议论文2篇，申请国家发明专利3项，其中授权1项、发授权通知书1项。在课题研究过程中培养博士后1人。