微细切削芳纶纤维复合材料表面创成机理研究

Aramid fiber composite materials has broad application prospects in many areas for its light weight, high strength, high toughness characteristics. The next processing of the materials is cutting with smaller scale in micro cutting. Because of the surface creating mechanism in the cutting is not very clear, So the cutting defects are often found and the further application of the material is limited. In the application, the study is the following:(1)to establish the three-dimensional model of aramid fiber composites with the structure of 2D woven unit cell model based on morphology, and then the cutting simulation using ABAQUS is carried out, the fracture Characteristics and mechanical properties of aramid fiber composites is studied by chip Shape in cutting performance, and thus the strength failure criteria of composite materials can be gained in different thresholds;(2)the cutting forces, heat, surface quality is studied in the micro cutting experiment to explore the mechanism of formation and distribution of cutting defects, the reasonable choice of cutting parameters and process can reduce and avoid processing defects; the friction test of tool material is executed to study the mechanism of friction and wear in the cutting process to create the finished surface of aramid fiber composite;( 3 )the geometry Flute of micro-cutting tools must be optimal designed with sharpness , easy chip cooling, reducing friction and wear, to strengthen the wear part of the micro cutting tools. And the best geometry flute of cutting tool with high strengthen will be studied in the application.

芳纶纤维复合材料以其轻质、高强、高韧的特性在多个领域具有广阔应用前景，其二次加工多采用切削方法且尺度较小，属微细切削加工，由于对其切削加工表面创成机理研究不够，经常出现加工缺陷，制约了该材料的进一步应用。本申请拟进行如下研究：(1)基于2D编织形态的单胞模型建立芳纶纤维复合材料的三维模型，进行微细切削全过程的ABAQUS仿真，研究其断裂力学特性，通过切屑形态研究其切削性能，进而提出不同阈值的复合材料强度失效准则；(2)进行切削力、热、表面质量的试验研究，探索切削加工缺陷的形成机理和分布规律，优选切削参数减少和避免加工缺陷的产生；针对刀具材料进行适配性摩擦试验，研究切削过程中摩擦磨损及刀具切削效能影响，为揭示表面创成机理奠定基础；(3)优化设计微切削刀具几何刃型使之既保持锋利度，又易于排屑散热，减摩耐磨，结合试验结果对易磨损部位予以强化处理，提出一种微切削刀具几何刃型设计准则和强化方法。

芳纶纤维复合材料属轻质、高强、高韧的新型复合材料，在各领域都有广泛的用途，但其二次加工易出现缺陷，制约了该材料的进一步应用。本研究旨在揭示该材料的切削断裂机理，研究避免其加工缺陷的工艺方法，研究内容及其成果主要包含：（1）针对该材料进行微细切削全过程的ABAQUS仿真，基于2D编织形态的单胞模型建立了芳纶纤维复合材料的三维模型，研究了其断裂力学特性；（2）通过试验研究了该材料的切屑形态即分为絮状切屑、块状切屑、盘丝状切屑，絮状切屑是切削状态良好的一种切屑，块状切屑出现在低速切削和切削条件恶化的情况下，盘丝状切屑表明切削刃开始出现磨损；（3）定义了该材料瞬时切削状态比α、纤维方向系数β、切削方向角γ，并研究了切削力随上述参数的变化趋势。试验表明X方向切削力随α单调增减，与β无关；Y方向切削力与纤维方向系数β相关，当β=1时，即切削进给方向与上层纤维一致时出现波谷，β=-1时出现波峰；Z方向切削力与Y方向切削力峰谷异向，即当β=1时出现波峰，β=-1时出现波谷；（4）通过切削力试验得出了切削力的变化规律，即宏观上呈现出周期性、震颤性、单调性，切削力分力Y、Z方向呈现峰谷异向性，研究了切削力对复合材料编织状态的复映规律，发现了切削中的单齿切削现象及其对表面质量的影响；（5）对比了常温和超低温环境下，微细切削芳纶纤维复合材料的表面质量，结果表明，超低温环境可使纤维断裂彻底，避免烧蚀现象，减少刀具磨损，获得较低的表面粗糙度值，Ra最小值可达到1.47μm；发现了芳纶纤维复合材料切削加工后表面特有的白色凝胶现象，初步探索了风冷排屑的工艺方法和基于控形控性技术的刀具优化设计。本研究探索了该材料的结构建模方法和切削工艺现象，揭示了切削断裂机理和切屑形成规律，提出了改进表面质量的工艺方法，推进了芳纶纤维复合材料的二次加工技术，为其进一步应用奠定了试验基础，积累了试验数据和初步的工艺探索。