Abstract Exit damages such as burrs and delamination frequently occur during the CFRP drilling. Tool geometry strongly influences drilling performance. In this paper, the advantages of dagger drill and brad-spur drill are analyzed and a pulling-shearing effect is proposed. According to the pulling-shearing and the cut-push effects, a step-control scheme for reducing the CFRP delamination is proposed to design a novel drill bit. Theoretical and geometrical analyses of the drilling process and drilling tests have been carried out on CFRP composites. The results indicate that the pulling-shearing and the cut-push effects can be successfully implemented by the novel drill with V-shaped cutting edge. Due to the pulling-shearing and the cut-push effects, the fibbers along the hole edge can be cut off cleanly when the novel drill penetrates the last ply. Then the damages can be reduced significantly. The changing trend reflected from the tests is basic anastomotic with the step-control scheme. Compared with the dagger drill and the brad-spur drill, the novel drill has a good performance on reducing the thrust force as well as the damages. However, some defects such as the tearing are easy to generate when the feed per revolution is high.

中文翻译：

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基于步进控制方案减少碳纤维布分层的新型钻头

摘要 CFRP钻孔过程中经常出现毛刺、分层等出口损伤。刀具几何形状对钻孔性能有很大影响。本文分析了匕首钻和斜角钻的优点，提出了拉剪效应。根据拉剪效应和切推效应，提出了一种减少CFRP分层的步进控制方案，以设计一种新型钻头。对 CFRP 复合材料进行了钻孔过程和钻孔试验的理论和几何分析。结果表明，新型V型刃口钻头可以成功实现拉剪和切推效果。由于拉剪和切推效应，当新型钻头穿透最后一层时，沿孔边缘的纤维可以被干净地切断。那么损害可以显着减少。测试反映的变化趋势与步进控制方案基本吻合。与匕首钻和白马刺钻相比，新型钻头在减小推力和损伤方面具有良好的性能。但每转进给量大时，容易产生撕裂等缺陷。