Self-excited vibrations in turning : Forces torsor analysis

TL;DR

This study investigates self-excited vibrations in turning processes by analyzing forces and moments using a 3D model, revealing how vibrations influence system mechanics and chip characteristics.

Contribution

It provides a detailed analysis of vibrations' effects on turning mechanics, including force measurements and elliptical motion patterns, with a focus on the role of self-excited vibrations.

Findings

Existence of tool tip moments confirmed by six-component dynamometer.

Fundamental frequency of 190 Hz observed across displacements and efforts.

Elliptical evolution of application points correlates with feed rate and power.

Abstract

The present work deals with determining the necessary parameters considering a three dimensional model to simulate in a realistic way the turning process on machine tool. This paper is dedicated to the study of the self-excited vibrations incidence on various major mechanics characteristics of the system workpiece / tool / material. The efforts (forces and moments) measurement using a six components dynamometer confirms the tool tip moments existence. The fundamental frequency of 190 Hz proves to be common to the tool tip point displacements, the action application point or at the torque exerted to the tool tip point. The confrontation of the results concerning displacements and efforts shows that the applications points of these elements evolve according to similar ellipses located in quasi identical planes. The large and the small axes of these ellipses are increasing with the feed rate motion values accordingly to the mechanical power injected into the system. Conversely, the respective axes ratios of these ellipses are decreasing functions of the feed rate while the ratio of these ratios remains constant when the feed rate value is increasing. In addition, some chip characteristics are given, like the thickness variations, the width or the hardening phenomenon.