Model for the prediction of heterogeneity bands in the topography of surfaces machined by peripheral milling considering tool runout

摘要

This paper presents a model for the prediction of heterogeneity bands in the topography of surfaces machined by peripheral milling accounting for tool runout. Ideally, when the tool is clamped in the toolholder, all the cutting edges of the tool are located at a distance equal to the tool nominal radius from the rotational spindle. However, tool runout causes each cutting edge to be at a different radius from the spindle axis and this affects the topography of the milled surfaces. The proposed model includes the effects of two factors that produce tool runout: tool setting error and cutter grinding errors (CGE). The influence of tool setting error on the surface topography in peripheral milling has been widely modelled in the literature in the past but the contribution of CGE has not been investigated so far because these errors were relatively smaller. With the increasing precision of toolholders, the magnitude of both errors is similar and therefore, the influence of CGE on the surface topography can no longer be neglected. In this paper, an expression for the effective radius of the cutting edges taking into account tool setting error and CGE is first derived. Next, a model for the prediction of heterogeneity bands is presented. A detailed study of band formation was carried out that makes it possible to study the influence of tool runout and feed on the band geometry (position and width) and on the roughness variations along the milled surface. Finally, cutting tests were conducted in order to validate the proposed model by comparing the experimental results with the predicted ones and a good agreement between them was found.