Research On NC Machining Technology Of Curve Surface Based On Reverse Engineering

As a new way to solve problems in product development, reverse engineering gets more and more attentions in modern manufacturing. The key NC machining techniques of the complex surface in reverse engineering are studied theoretically and practised in this paper including the processing method of point-clouds data, the reconstruction of complex surface, the NC machining tool-path generation and the development of post-processing program etc., which has great importance in the reverse engineering and NC machining for complex surface.The data collection and processing of complex surface as well as model reconstruction are studied. Based on Imageware software, the process of constructing high precision NURBS curves and surface are analyzed, take an impeller blade as the example, reverse measurement, reverse analysis and reconstruction are practised.Aiming at the efficiency problem occurred in the complex surface machining with ball-end mill and multi-axis NC machine tool, some key problems are researched theoretically including calculation of cutter's location, analysis and compensation of machining error, calculation of cutting step length and cutting line width, calculation and selection of tool radius in the complex surface machining with five-coordinate NC machining and flat-end cutter. The relationship among the effective cutter radius, the milling remain height and the inclination angle is established and the influences of inclination angle, path interval, cutting speed and feed rate on the surface roughness are analyzed by experiments, and the best matching relationship among some related parameters in tool path-planning are obtained. The interference-free tool path generation method based on the iso-scallop is given. The calculation methods of cutting step length and row spacing are analyzed, meanwhile, the corresponding algorithm is given. Experimental research on NC machining of impeller blade's surface based on reverse engineering is carried out systematically, which proves the feasibility of the method given above.As an important part in the NC programming, the function of post-processing is to transfer the cutter location file into the NC program suitable to NC machine tools. Aiming at the post-processor development of 5-axis NC machining automatic programming, the main tasks, contents and processing flow are analyzed. With MAHO800C—a dual-rotary-table 5-axis machining center as an example, the motion relationship and solution formula is given. Based on UGNX/Post Builder software, the post processor for MAHO800C is developed, which realizes the conversion of the point position and contour machining cutter location file to NC program, and the post processing program has been verified effectively in practical machining.