基于激光加热辅助的高温合金高效铣削界面热影响规律及实验研究

Focusing on the low cutting efficiency and high tool wear rate in machining of superalloy, a set of theory and method using laser heat as input energy concerning the key mechanism and process technology are proposed in this proposal. Based on the re-crystallization process of the material, the flow stress description equation of wide temperature range considering the strain hardening, the flow softening and the softening effect is established under the action of the laser heat source, which can be used to optimize the process parameters in laser assisted machining (Problem 1). Then, a cutting temperature prediction model considering the coupling effects of laser heat and cutting heat based on heat transfer theory is established to calculate the temperature gradient distribution of the machined surface, aiming to solve the issues such as over-heating or less-heating (Problem 2). Thirdly, a laser assisted machining system platform is built to complete the milling tests. Through the above research, the theoretical methods, key technologies and technological schemes of "material characterization - heat prediction -process planning- wear control- efficiency improvement" in milling of super alloy are applied in enterprise production.

针对当前高温合金切削效率低、刀具磨损快的加工现状，本项目提出一套激光加热辅助高效铣削理论与方法，并围绕实际应用中的两大难点，开展核心机理和工艺技术研究。基于外界能场影响下的高温合金材料再结晶过程，建立激光热源作用下考虑应变强化、流动软化和热软化效应耦合的宽温范围材料描述方程，突破能场输入下材料力学性能表征困难引起辅助工艺参数难以优选的问题（难点1）；此外，综合考虑激光外界热源和切削热源的耦合作用，结合热传导理论和实验获得的热量分配比例模型，采用切削热应力计算模型及耦合热源温度预测模型实现对切削表面/亚表面温度场准确预测，解决热辅助工艺下切削温度难以控制从而造成的“过热”或“欠热”问题（难点2）；搭建激光加热辅助铣削系统平台，完成铣削工艺试验。通过以上研究内容，形成高温合金高效铣削“材料表征-温度预测-工艺规划-磨损控制-效率提升”的理论方法、关键技术和工艺方案，应用于企业实际生产。

高温合金以其在高温高压条件下优异的服役性能使得其在航空发动机中广泛使用，然而这类材料在加工过程中存在切削效率低、刀具磨损快等问题。围绕以上问题，基于刀具-工件切触几何变化与材料流动应力分析，研究刃口驱动下的材料塑性变形机理，揭示了不同微刃条件下的材料滑移规则，进一步建立了高温合金高效切削过程动态切削力分布规律模型；此外，综合考虑切削过程多热源的共同影响，将加工微元进行离散化处理，分别计算出接触面两侧各点不同热源共同作用的温升分布曲线，进一步引入非均匀热分配系数模型对两侧温度曲线进行匹配，实现了三维切削温度场的准确预测；在此基础上搭建了高温合金预热加工实验平台，提升了难加工航空材料加工效率。