Modeling and experimental investigation of drilling force for low-frequency axial vibration-assisted BTA deep hole drilling

Abstract

The ability to form regular chips and evacuate them smoothly is crucial for deep hole drilling. In this work, an eccentric cam mechanism is used to apply low-frequency axial vibration at the end of the drill tube for boring and trepanning association (BTA) deep hole machining, and the instantaneous cutting thickness equation of low-frequency axial vibration assisted drilling is derived, which can actively control the length of the chip and achieve a good chip removal effect. Considering the variable geometric parameters and the scale effect of teeth cutting, a new analytical model is established to obtain the instantaneous drilling force of staggered teeth BTA deep hole drill assisted by low-frequency axial vibration. The relevant parameters in drilling force model are identified, and the distribution laws of the normal friction angle, normal shear angle, and shear stress with instantaneous cutting layer thickness and drilling radius values are achieved. The influence of the vibration drilling process parameters, including feed, speed, amplitude, and frequency ratio, on the drilling force is investigated experimentally, and the validity of the drilling force model is verified. These results show that the drilling force model is reliable, and the thrust and torque of the low-frequency axial vibration assisted drilling relative to ordinary drilling are reduced by 21.63% and 13.74%, respectively.