Novel micro-deep-hole drill with variable web thickness and flute width

Abstract

This study proposes a novel micro-deep-hole drill with variable web thickness and flute width to effectively improve the problem of tool breakage and chip clogging during micro-deep-hole drilling. Firstly, the failure form and failure mechanism of micro-drill are explored by performing drilling experiments, and it is found that the torsion fracture and bending fracture are the main premature failure modes of micro-deep-hole drilling tools. The static simulation analysis of micro-drill is further conducted to investigate the influence of geometric parameters on the stiffness and strength of high-aspect-ratio micro-drill, and the results indicate that the web thickness ratio and flute width have significant effects on drill tip stiffness and spiral groove root strength. To balance the rigidity, strength and chip evacuation capability of micro-deep-hole drilling tools, the new micro-drill with variable web thickness and flute width is developed, supplemented by comparative experiments. The results confirm that the new micro-drill has better chip removal ability, greatly reduces the drilling force, torque, drill tip wear and material peeling phenomenon, and significantly enhances the machining quality of hole wall.