Towards an Approach for Rapid Copying of Free-Form Surfaces in 5-Axis Machining

摘要

The paper deals with the various steps of free-form copying from surface acquisition to machining using five "positioned" axes. The originality of the proposed approach is to be free from surface reconstruction. The object surface acquisition is performed using an optical digitizing system in order to obtain a representative image of the real surface. Relative positions and orientations sensor/surface are chosen to guarantee the completeness of the digitized points as regards the whole object surface. The next step concerns the pre-processing of the points. Indeed, the data are discrete, non-homogeneous, dense and noisy. Cleaning, filtering and densification are essential steps. A voxel representation of the data is carried out with the objective to recreate "pseudo-continuity". Therefore, the calculation of local characteristics such as local normal to the discrete data is thus possible. The last step is the choice of optimal part set-ups for the machining using five positioned axes. To initialize the automatic research of the best set-up, each relative orientation sensor/surface may define one set-up. For each set-up, the trajectory of the ball-end cutter tool is calculated in three axes, using the offset inverse method. The feasibility of the whole approach is illustrated through an example.