Design optimization of a split-point drill by force analysis

A modified force model incorporating the splitting parameters for predicting the thrust forces and torque of a split-point drill has been developed. The effect of the notch angle on the thrust forces and torque has been deduced, also from the proposed force model. Experiments were conducted to evaluate the thrust forces and torque, the calculated thrust forces and torque being shown to compare favorably with those obtained from drilling tests on a JIS S45C steel. The optimization of the drill-point geometry was obtained by minimizing the thrust forces and torque, as well as by using the finite-element method to compute the displacement and stress distributions of the drill point. According to the experimental results for both thrust forces and torque, and the calculated values of the maximum displacement and maximum stress at the drill point, the optimal value of the notch angle was about 57.7 degrees.