Prediction of surface quality considering the influence of the curvature radius for polishing of a free-form surface based on local shapes

When machining a free-form surface automatically and digitally, especially in the case of sophisticated surface shapes, it is very difficult to control the surface quality, and thus sophisticated surfaces are usually polished using manual labor. Over the past few years, there has been little attention to the calculation of material removal depth models and construction of theoretical roughness models considering the influence of the curvature radius. Bonnet polishing can be automatically adapted to polish complex free-form surfaces. This paper explores key problems related to forecasting surface quality with respect to bonnet polishing of free-form surfaces. First, for the convex and planar sub-regions, this paper deduces the relationship expressing the maximum pressure distribution and the curvature radius, and presents a computational expression for material removal depth, taking into consideration the influence of the curvature radius. An expression is also deduced for the dwell time relationship between the adjacent processing points according to the experimental results pertaining to the material removal depth. From this, a theoretical roughness model is constructed that relates the bonnet curvature radius and the workpiece curvature radius. The validity of the experiments is summarized in the conclusion. The research findings provide a basic theory for the prediction of surface quality that can be automatically adapted to a free-form surface shape in bonnet polishing.