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碳纤维/环氧树脂(C/EP)复合材料制孔毛刺和撕裂缺陷,对构件的装配精度影响较大。为了揭示C/EP复合材料制孔毛刺和撕裂缺陷的形成机制,采用微米划痕试验研究沿不同纤维方向切削加工时材料的破坏去除过程,并用FEI公司Quanta 200环境扫描电镜对划切后的沟槽及切屑的形貌进行观察分析。结果表明:当划切方向与纤维方向垂直时,划切力最大,较易产生撕裂缺陷;当划切方向与纤维方向呈30°、45°和60°时,划痕左侧纤维受到压头挤压向左退让并弯曲,产生锯齿形断裂,否则形成毛刺;划痕右侧纤维为避让压头发生较大的弯曲变形,纤维断裂均匀,不容易形成毛刺。理论分析和划痕试验结果表明:制孔加工时,纤维方向与刀具旋转方向成钝角的区域容易产生毛刺缺陷,与刀具旋转方向成锐角的区域边缘光滑,与刀具旋转方向垂直的区域容易形成撕裂缺陷;出口缺陷与试验结果一致。
Carbon fiber / epoxy (C / EP) composite burrs and tear defects, the assembly accuracy of the assembly. In order to reveal the formation mechanism of burrs and tear defects in C / EP composites, microdis scratch test was used to study the material removal during the cutting process in different fiber directions. The scratched and eroded samples were cut by FEI Quanta 200 environmental scanning electron microscope Trench and chip appearance observation and analysis. The results show that when the direction of cut is perpendicular to the direction of the fiber, the maximum scribing force is more likely to result in tearing defects. When the direction of scribing is 30 °, 45 ° and 60 ° to the fiber direction, Head extrusion to the left concession and bending, resulting in zig-zag fractures, or the formation of glitches; scratches on the right side of the fiber head to avoid large bending deformation, fiber breakage is not easy to form burrs. The results of theoretical analysis and scratch test show that burring defects are easily generated in the area of the obtuse angle of the fiber direction and the tool rotation direction during the hole making process. The edges of the area at an acute angle with the rotation direction of the tool are smooth and the area perpendicular to the rotation direction of the tool is apt to form the tearing Crack defects; export defects consistent with the test results.