Geometric Accuracy Design Method of Roller Cavity Surfaces for Net-Shape Rolling Compressor Blades

Abstract

The accurate shape of roller cavity surfaces is vital part for net-shape rolling. This paper presents a new design method of roller cavity surfaces with high accuracy for rolling compressor blades based on the geometrical inheritance and evolution of the net-shape profiles. Firstly, a process model of the blade is modeled by adding process allowance and locating basis at the CAD (Computer Aided Design) model of the blade to represent the roll formed blade, the process model inherits the net-shape profiles of the blade at the pressure and suction surfaces. Secondly, an algorithm is proposed to discretize a curve to a set of ranked points with the restriction of the maximum chord height, and a new section curve which represents the geometrical feature of the pressure and suction surfaces are distributed on the process model based on the algorithm. Finally, a mapping algorithm is proposed to transform the section curves to the cavity section curves around the roller axis based on the conjugate movement between rollers and blade, and the cavity surfaces are reconstructed based on the transformed section curves. The design method is implemented for the roller cavities of a variable cross-section compressor blade, and the accuracy of the designed cavities is checked based on the precision of the roll formed blade by the finite element method. The results reveal that the designed cavities achieved the net-shape precision at pressure and suction surfaces of the blade. The paper provides an effective method for designing rolling cavity surfaces with excellent design quality.