| Parts and components with complicated curves and surfaces are widely applied inthe field of energy, transportation, national defense and electronic products, such aspropeller in fleet, shield of spacecraft, impeller of aero-engine and the precise modules ofthe cars’ covering parts. The sophisticated manufacturing process will enhance thecompetitiveness in the market. The key technology in the manufacturing process is thegeometric model of the complicated curves and surfaces and the tool-path plans.Non-Uniform Rational B-Spline (hereafter NURBS) is adopted in the modeling toattain the square/cubic curves and the expression of square-cubic/cubic-cubic NURBSsurface matrixes. Based on the output, the square curve of circle/arc is expressed inNURNS and then geometric model of complicated surface is established. Differentialgeometry parameters of the model is then calculated and analyzed. According to thedistribution of Gaussian curvature, average curvature and main curvature, thecomplicated surface is divided into different sections. Different tools and correspondingplans are selected for each section.Annular milling cutter using advanced constant scallop-height method in thetool-path planning process is described in the following report. By analyzing thecurvature of the surface and cutter at the contact point, the feeding step length is attained.By identifying the intersection point of the effective cutting shape and the offset line ofthe scallop height, the effective processing width is attained. Then the step length andeffective processing width are calculated correspondingly. The research also analyzes theinfluence on the processing efficiency imposed by the postures of the milling cutter andthen adjusts and determines the best posture. At the end of the research, calculationsbased on differential geometric features of the surface and simulation of the geometricmodeling and tool-path planning for the divided sections of the complicated surface arecarried out by the software MATLAB. |
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