Analyzing and modeling the effects of tool edge geometry in machining.

摘要

The objective of this work is to comprehend the effect of unsharp tool edge geometry in metal cutting to enable more valid modeling yielding improved accuracy in force predictions in the future.; An application of white light interferometry is developed for accurately and efficiently measuring the edge radii of cutting tools. A statistical study on samples of commercial, brush honed, carbide cutting inserts indicates that the radius of the hone varies parabolically along the length of the edge. This has significant implications for cutting model formulation, calibration testing and model application. Statistically significant edge radius variations are also seen in the insert comer region where much cutting occurs in turning, boring and face milling.; Two experimental methods have been suggested in the past to extract a presumed ploughing (non-cutting) component from the (total) measured force when cutting with unsharp tools; (1) an extrapolation approach and (2) a dwell force technique. This study reports the behavior of zinc during orthogonal cutting, using tools of controlled edge radius. It is determined that neither the extrapolation nor dwell approaches yield a material response that is consistent with the known behavior of zinc and are thus invalid. A new analysis based on changes in the deformation zone resulting from changes in tool geometry yields the expected material response without requiring recourse to an additional ploughing component.; The influence of varying lengths of zero clearance flank in combination with controlled edge radii is also studied. Analysis shows zero clearance flanks do generate a ploughing force and that the magnitude of this parasitic force is a function of the land length. If this parasitic force is subtracted from the total force, the analysis reduces to consideration of the hone alone. Thus a zero-clearance land does not affect chip formation mechanisms under conditions studied here while machining zinc.