Kinematic analysis of the dynamic contact in ultrasonic-assisted cutting based on the moving frame method

Abstract

The dynamic contact characteristics between tool and workpiece (DCCTW) significantly affect the lubrication and cooling in ultrasonic-assisted cutting, closely related to tool wear and machining quality. Due to the complexity of the contact, it is hard to describe them effectively, which limits the understanding of the ultrasonic-assisted cutting mechanism. In this paper, a novel kinematic analysis method based on the moving frame method is presented to describe the DCCTW in ultrasonic-assisted cutting. In the kinematic modeling, the tool nose radius and tool vibration characteristics are both taken into account. The method can display visually the dynamic contact characteristics of each position on the cutting edge in one vibration cycle using velocity mapping diagrams (VMD). Using the method, DCCTW in three types of typical ultrasonic-assisted turning are compared theoretically, which provides a novel perspective to understanding their cutting mechanism. Additionally, experiments about ultra-precision turning optical steel mold using single-crystal diamond tools to manufacture micro-grooves are carried out using our developed elliptical ultrasonic vibration system. The proposed method gives an intuitive picture of the DCCTW in the ultrasonic elliptical vibration turning and is successfully applied to analyze the tool wear and surface quality under different machining conditions.