复杂零件的五轴增减材混合制造工艺规划及优化

Parts with complex structure and surfaces are extensively applied in aerospace, automotive and energy industries. Traditional five-axis machining process is sometimes delicate when handling complex parts, in the sense that the design requirements cannot be fully satisfied. The integration of additive and subtractive manufacturing process into a unique five-axis apparatus offers a new way for manufacturing by a sequence of additive and subtractive alternating processes. Nevertheless, the tool-workpiece interference is hardly predictable due to the geometric growing of the workpiece after each alternating process, which makes the process planning a challenging task. Conventionally, conservative processing strategies divide the part into uniform thin layers, each of which is alternately fabricated one after another. With too many alternations, both the processing efficiency and the surface quality are greatly violated. Motivated by this dilemma, this project proposes a dedicated strategy for five-axis hybrid manufacturing process. By investigating the tool accessibility and the kinematic property of five-axis machine, a concept of “manufacturability” is presented as a constraint to evaluate the complexity for processing a local area of the part. A novel downward searching strategy is then proposed for process planning individual machining features of the part, which effectively reduces the total number of alternating processes, while satisfying the manufacturability constraint. For each optimized process, the generation of feasible five-axis additive and subtractive tool path is also introduced. This new methodology is believed to provide both technical and theoretical support to the hybrid manufacturing of complex parts.

航空航天、汽车及能源等行业存在大量复杂结构及复杂曲面零件，采用传统五轴切削加工往往工艺复杂，甚至难以满足设计需求。五轴增减材混合制造方法是一种增材与减材的多工序交替制造新模式。然而，制造过程中工件几何增长，导致刀具干涉难以预测且前后工序相互制约。针对该问题，目前多采用保守分层工序规划，工序繁多，影响加工效率和零件表面质量。本项目提出五轴增减材混合制造工艺方法，针对五轴机床建立了零件局部可加工性模型，用于表征刀具可达性与机床运动特性双重指标，并以此为准则建立约束条件，提出“倒序下探法”对零件进行分层工序规划，进而提出针对每道工序的五轴增减材刀轨生成算法，为复杂零件的混合制造提供了系统性理论基础与技术支撑。

航空航天器的关重零部件广泛采用复杂结构和复杂曲面设计，此类零件的制造工艺往往高度定制化，造成产品迭代周期长、制造成本高等一系列问题。增减材混合制造集成了增材与减材制造的各自优势，是实现复杂零件高精高效制造的有效手段，已成为高端制造业重点发展的方向之一。本项目围绕复杂零件多轴增减材制造工艺规划中的几何切片、轨迹规划难题开展研究工作，主要成果如下：.（1）针对复杂零件的几何切片工艺，突破了传统基于平面剖分的几何切片方法需要额外添加辅助支撑的问题，提出了基于曲面剖分的复杂零件几何切片工艺方法，为实现无支撑增减材工艺规划奠定了技术基础。.（2）针对复杂曲面的刀具运动轨迹规划，突破了传统以图形为载体的轨迹规划方法难以适应多工艺约束下的规划难题，提出了以图像为载体的刀具运动轨迹整体规划方法，建立了复杂曲面特征的图像参数域模型，进而探明了工艺约束与图像处理的等效关系，实现了复杂零件的增材制造及减材加工轨迹的高效高质量整体规划。.（3）基于本项目开发的原型系统已应用于C919大型蒙皮镜像铣数控编程，与商品化CAM软件相比，提高数控编程效率4倍以上、加工效率20%以上，成果获2021年度江西省科技进步一等奖。