Study On Surface Subdivision And Tool Path Planning Of Automotive Panel Dies

Along with the rising demand of automotive market and the rapid progress ofproduction and processing technology, it has taken more and more attention onNC machining about the dies of automotive panels. This free-form surfaceswhich contain the irregular distribution of curvature like automotive panels, thereis no doult that the difficulty of extracting and analysing surface featureinformation will increase. At the same time, the requirements for NC machiningplanning will improve. The research on tool path generated is particularlyimportant in NC machining for free-form surfaces, so the tool path generation isnot only directly related to the machining precision but has significant effect onthe machining efficiency. Therefore, in view of the above problems, this thesishas a depth study on surface subdivision planning of dies, geometric theoryanalysis of tool path and method of tool path generation.Firstly, the thesis studies the surface features of dies of automotive panel anddivides the surfaces preliminarily by geometric properties and processingcharacteristics of free-form surfaces; Based on K-means fuzzy clustering and themedian split method, accurate surface subdivision is made. Then boundarys ofsub-surfaces are extracted by the method of parameterizing data of boundaryregion.Secondly, it selects a kind of cutters to mill the dies with large size surfaces,analyzes the geometrical relationship at the point of contact between the tool andthe surface in cutting and builds the movement envelope model of the tool. Basedon this model, it calculates the effective radius of the cutter, further more certainsthe step length and calculates step-over distance.Thirdly, based on the differential geometry theory of tool path, the influenceof various factors on the SOD is analyzed. Then improvement scheme of constantscallop height is put forward by considering the influence law of SOD. The toolpath planning is made by combining surface subdivision model with the optimizational constant scallop height.Finally, the thesis makes milling.experiments about the surface subdivisionand the overall surfaces.Using Matlab and Powermill, simulations of the twosituations are compared.And the results after processing are analyzed. Theexperiment result shows that, under the same accuracy condition, the tool pathplanning method proposed shortens the total track length and improves theprocessing efficiency compared with the traditional iso-parameter planning toverify the accuracy and effectiveness of the method.