高粘度碳纤维预浸料短切机理及其粘刀脱附机制

Chopped carbon fiber (CF) prepreg, whose key technology is chopping with high-efficiency and low-cost, is one core material to manufacture CF reinforced composite parts which can support heavy load-bearing in the vehicle industry. However, it is lack of available theories on the manufacturing method and tool design so far. Due to its high viscosity and multi-field characteristics, the chopped CF prepreg behaves totally differently with metals and traditional composites during cutting. Therefore, in this project, the fracture behaviors of the CF prepreg will be investigated, and a novel method to control the sticking phenomenon of tool will be presented. A typical CF prepreg with thermosetting epoxy resin under high viscosity state will be used. Several physical properties during cutting process will be investigated, including the interface behavior between cutting tool and workpiece, the fracture process of CF prepreg and the mechanism of tool wear. According to the theory of non-smooth microstructure reducing viscosity and anti-friction, a layer of anti-adhesion microstructure will be introduced on the surface of cutting tool. The influence of microstructure characteristics, e.g., shape, arrangement and size, on the function of anti-adhesion will be discussed. Therefore, a new microstructure design method for preventing chemical adhesion on tool during chopping will be established. As such, this new cutting tool will be manufactured efficiently combined with laser engraving and coating technology. At last, experiments will be conducted to validate the effectiveness of this new microstructure. The implementation of this project will establish a technique and theoretical system of the chopped CF prepreg processing, will enrich a theoretical system concerning the cutting tool design and manufacture method under a high viscosity situation, and will promote the manufacture and application of the main load-bearing components with three-dimensional (3D) complex structure made from CF reinforced composite under high-efficiency and low-cost.

短切碳纤维预浸料是制造汽车碳纤维主承力结构件的核心材料，高效低成本短切是其关键技术，尚缺乏加工和刀具设计理论。针对有别于传统加工对象（金属和传统复合材料）的高粘度、多场等特性，项目开展碳纤维预浸料短切过程分析及其粘刀问题控制研究。以典型高粘度热固性环氧树脂碳纤维预浸料为研究对象，揭示刀具-工件在切断过程中的界面行为、预浸料的断裂过程、刀具磨损理论。引入非光滑减粘降阻理论，在刀具表面设计出具有脱附功能的微结构，探讨形状、排布、尺寸对脱附功能的影响，构建刀具切削加工时防止化学粘附的表面微结构设计理论体系；采用激光雕刻和涂层技术，实现短切刀具微结构的高效制造，验证脱附微结构设计理论体系的有效性。项目的实施，将建立短切碳纤维预浸料加工技术与理论体系，丰富高粘性服役环境中的刀具设计与制造理论体系，推动三维复杂曲面碳纤维主承力结构件的高效低成本制造和应用。

短切碳纤维预浸料的高效切断技术是锻造复合材料的关键，尚缺乏加工和刀具设计理论。.项目开展了碳纤维预浸料的断裂机理、刀具微结构设计、刀具磨损、微结构参数优化、质量评价等研究。取得的主要理论成果如下：（1）建立了三种不同支撑状态下碳纤维预浸料切割断裂过程几何模型，发现刚性支撑下切断力取决于底层碳纤维单丝的数量，柔性支撑下碳纤维的断裂形式是弯曲断裂，无支撑条件下具有最小的支撑体环氧树脂粘附量。（2）研究了激光加工参数对双尺度微结构的影响，发现通过减小突起阵列结构的直径和间距，增加突起的高度，提高双尺度微结构表面的粗糙度，可以减小固-液接触界面，获得更佳的疏水和液滴脱附性能。（3）研究了碳纤维复合材料与金属材料球-面接触的干摩擦行为，发现了摩擦过程中转移膜的正向转移和反向转移现象。（4）对环氧树脂在织构化刀具表面的流动性能进行了仿真和试验研究，发现混合沟槽织构具有更好的润滑性能。（5）提出了织构化刀具在碳纤维预浸料短切工艺中的应用，揭示了其中的切断机理，发现刀具侧面沟槽对环氧树脂的动压润滑效应以及刀刃上凹坑的微切削作用。（6）探讨了模压成型参数和材料结构参数对CFFC的性能影响关系，发现了干摩擦下和水润滑摩擦下分别形成的转移膜和水润滑膜能够有效的降低复合材料的摩擦系数。.项目在J Mater Process Technol、Text Res J等国内外权威期刊上发表学术论文24篇，其中SCI收录22篇，EI收录2篇，培养研究生7人。项目的实施，丰富了碳纤维预浸料短切技术理论体系，有效的促进了碳纤维产业的发展。