CFRP新型钻-铣复合螺旋制孔专用刀具设计及其制孔缺陷抑制研究

A variety of damages are easy to produce during the drilling of CFRP, such as, burrs, delamination, as well as the tear. These problems will seriously hinder its extensive promotion and application. According to the pulling-shearing cutting principle, the drilling-milling compound tool is presented. Then, the theory and application on the multi-process integration of the drilling and the helical milling will be researched. All the processes of the drilling and the helical milling are analyzed, as well as the morphologies of their cutting surfaces and chips. The mechanisms of the fiber breakage and the matrix failure, and their relationship to the time-varying characteristics of the cutting forces are presented. Meanwhile, the cutting forces model is obtained. The association model between the cutting forces and the top layer damages of the fibers, matrix and their interface is studied. In meso-level, the theoretical damage model of the top layer defects induced by the cutting forces is obtained. Then, the formation mechanisms of the drilling and the helical milling defects are revealed, as well as the succession and evolution of the defects. Besides, the coordination mechanism between the cutter structure and the pulling-shearing effect is ascertained. Based on above theory models of the cutting forces and micro-damages, the association of “cutter structural parameters, process parameters → defects” is obtained. Next, the drilling-milling compound tool and the process are optimized. Then, the multi-process integration of the drilling and the helical milling is achieved. These research achievements will promote the development and adaptation of the fundamental theory for the efficient and noninvasive hole processing technology of the CFRP.

CFRP制孔中极易产生毛刺、分层、撕裂等缺陷，严重阻碍了其大量推广和应用。针对直径d≥6mm的孔加工效率低下、制孔缺陷难以控制问题，提出基于纤维拉-剪切除原理设计制造钻-铣复合专用刀具，开展钻孔/螺旋铣孔多工序一体化制孔的基础理论和应用研究。分析钻孔/螺旋铣孔过程及切削表面、切屑形态，揭示拉-剪效应下纤维断裂、树脂破损的材料去除特征及其与切削力时变特征的关联关系，获得两步制孔流程的切削力计算模型；研究切削力与表层纤维、基体及其界面破损之间的关联模型，从细观层面获得切削力引起表层制孔缺陷的理论损伤模型，揭示两步制孔流程中制孔缺陷的形成机理及继承演变规律，探明刀具结构与拉-剪效应的协调机制；基于以上切削力模型和细观损伤模型，获得“刀具结构参数、工艺参数→制孔缺陷”的关联关系，优化钻-铣复合专用刀具及其工艺，实现钻孔/螺旋铣孔多工序一体化制孔，推动CFRP高效低损伤制孔技术基础理论的发展和应用。

碳纤维增强复合材料(CFRP)具备优的异性能，在航空、航天以及军工等领域广泛应用。然而，碳纤维增强复合材料在制孔加工时极易产生分层、毛刺、撕裂等加工缺陷。本项目通过设计制造新型结构的刀具来制孔，实现对CFRP制孔分层、毛刺、撕裂等缺陷的控制，提高CFRP制孔加工质量。项目围绕CFRP钻-铣复合专用刀具设计及其制孔加工机理、“切削力→制孔缺陷”的细观损伤建模及制孔缺陷抑制策略、钻-铣复合制孔两步制孔流程工艺优化展开研究。首先，结合CFRP微细观结构特征，构建CFRP三维切削模型，分析了CFRP单次切削和二次切削过程中纤维、树脂、界面等的破坏失效形态；基于纤维拉-剪切削去除原理，设计制造了CFRP新钻型，同时，建立了新钻型关键部位制孔缺陷形成的力学理论模型，分析CFRP制孔缺陷的形成机制；从理论和试验角度，深入分析了制孔缺陷形成机制，建立了“切削力→制孔缺陷”的细观损伤建模，提出了制孔缺陷抑制策略。再进一步地，在新钻型基础上进一步设计制造钻-铣复合一体化刀具，并采用钻-铣复合一体化刀具进行CFRP钻铣复合螺旋制孔试验，研究了螺旋制孔阶段的运动学规律、切削厚度的变化规律，分析了切削力的变化规律，以及切削力对制孔缺陷、孔径精度的影响规律，阐明了钻-铣复合螺旋制孔加工机理，探明了两步制孔流程中制孔缺陷的演变规律；构建了“刀具结构几何参数、工艺参数→制孔缺陷”的关联模型，协同优化刀具结构和工艺参数，获得了钻-铣复合螺旋制孔中螺旋铣孔阶段工艺参数的优化工艺参数。本项目的研究成果进一步完善CFRP材料的切削理论，拓展纤维复合材料工艺方法的改进及应用，为纤维增强复合材料加工提供可靠、实用的加工工艺方法和理论支持，推动复合加工技术的发展，相关成果可推广到相关无机纤维增强复合材料的加工制造领域。