Among material secondary machining, drilling is the most frequently applied factor to composites needing structure joining. Drill geometry is considered the most important factor that affects drill performance. A major concern in drilling of composite materials is the delamination that occurs in the exit as well as in the entrance planes. The delamination damage caused by the tool thrust is known as one of the major concerns during the drilling process. The thrust force of step drill with drilling parameters (step angle, stage ratio, feedrate and spindle speed) in drilling carbon fiber reinforced plastics (CFRP) laminates were experimentally investigated in this study. The experimental results indicate that the step angle, stage ratio, and feedrate are the most significant factors affecting the overall performance. The optimal combinations, such as A2B2C1D3 (i.e., step angle = 100 ° stage ratio = 0.4 mm/mm, feedrate = 0.01 mm/rev and spindle speed = 1,200 rpm), were used under the adopted drilling condition. An experimental approach to the prediction of thrust force produced by step drill using linear regression analysis of experiments and radial basis function network (RBFN) were proposed in this study. In the confirmation tests, RBFN (errors within 0.3%) has been shown to be a better predictive model than multi-variable linear regression analysis (errors within 28%) for quantitative prediction of drilling-induced thrust force in drilling of composite material.
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机译：在材料二次加工中，钻孔是需要结构连接的复合材料最常应用的因素。钻头几何形状被认为是影响钻头性能的最重要因素。复合材料钻孔中的主要问题是在出口以及入口平面中发生分层。由工具推力引起的分层损坏被称为钻孔过程中的主要问题之一。在本研究中，通过实验研究了在钻碳纤维增强塑料（CFRP）层压板中具有钻削参数（阶跃角，级比，进给速度和主轴转速）的阶梯钻的推力。实验结果表明，步距角，级比和进给速度是影响整体性能的最重要因素。最佳组合，例如A 2 B 2 C 1 D 3 （即，步角= 100°在所采用的钻削条件下，使用的工作台比= 0.4 mm / mm，进给率= 0.01 mm / rev，主轴速度= 1,200 rpm。提出了一种利用线性回归分析和径向基函数网络（RBFN）预测阶梯钻产生的推力的实验方法。在确认测试中，相对于多变量线性回归分析（误差在28％以内），RBFN（误差在0.3％以内）是一种更好的预测模型，用于定量预测复合材料钻削中的钻进推力。
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