Dispersed grinding wheel profiles for accurate freeform surfaces

Dispersed grinding wheel profiles are proposed to replace its ideal ones for planning 3D tool paths in CNC grinding. Its advantage is to register irregular and discontinuous grinding wheel profiles and directly eliminate their form-truing error for the accurate freeform surfaces of a large-size workpiece. First, the actually form-trued grinding wheel profiles were dispersed to be a tool point cloud by rotating the measured 2D wheel-section profile points; then a discrete-form algorithm was constructed to plan 3D tool paths on the base of a mutual-tangency between tool point cloud and workpiece point cloud; finally, the effects of discrete-form variables such as wheel spacing angle, lattice grid size and searching interval were investigated on discrete-form accuracy and efficiency. It is shown that the discrete-form algorithm may improve the form accuracy of ground freeform surface by about 37% compared with a normal-form algorithm. In discrete-form algorithm, the discrete-form accuracy increases and the discrete-form efficiency greatly decreases with decreasing wheel spacing angle, lattice grid size or searching interval, but the discrete-form error may converge to the wheel-section profile error. It is confirmed that the lattice grid size in 0.5 mm and a large searching interval may be employed to enhance the discrete-form accuracy and efficiency simultaneously.

► The discrete-form algorithm with dispersed grinding wheel profiles can directly register irregular 3D wheel profiles during CNC grinding even if its form-truing error is large.
► The discrete-form algorithm can improve the form accuracy of ground freeform surface by about 37% compared with a normal-form algorithm.
► The discrete-form variables are used to control the discrete-form accuracy and efficiency. The lattice grid size in 0.5 mm and a large searching interval are alternative.