A Stability Solution for the Axial Contour-Turning Process

Abstract

This paper presents an investigation of the stability variations in contour turning process. An equivalent chip-area formulation has been developed, and is used to model the dynamic machining forces. In order to establish a frequency domain solution for stability in the presence of geometric and structural variations along the tool path, the tool path is discretized into a finite number of portions, each of which possess constant geometric and structural properties. The stability solution developed here is capable of accommodating the effects of cutting conditions (axial and radial feed, depth of cut, and spindle speed), tooling geometry (lead angle and corner radius), workpiece geometry (contour tool path) and structural parameters (the mass, stiffness, damping ratio and orientation of the dominant mode). The stability solution is experimentally validated by machining a workpiece with a concave-convex contour combination. The solution has been applied to achieve productivity improvements via spindle speed regulation. A case study that includes contour turning of an aluminum wheel is also presented.