Modeling and machining of integral impeller based on NURBS curve

Abstract

NURBS curve is applied to model and machine of integral impeller to get better smooth streamline in this work. In order to get high precision surface modeling of impeller, complex surface modeling method for impeller is studied through inputting NURBS curves and surfaces obtained by MATLAB into CAXA Manufacturing Engineer, which solves the problem that cannot be designed NURBS curve and surface directly in the CAD software. Grooving and expanding groove tool paths are obtained according to the NURBS curve of top curve and root curve, and its interpolation step size and the row spacing are determined according to the curvature of the curve and interpolation period. Meanwhile, five-axis side milling method is used to achieve the vane finish machining, and streamline processing method is adopted to realize the finish machining of the channel. All work is verified in a virtual simulation system of 5MC850-C machining center, and these simulation results show that machining accuracy error of the impeller is between − 0.007 and 0.012 mm, meeting tolerance range of the impeller design.