Geometric modelling of thin-walled blade based on compensation method of machining error and design intent

Abstract

Due to the low stiffness of the thin-walled aero-engine blade milling process, the machining errors cannot match the tolerance requirements and thus limit the aerodynamic performance. Previous research mainly focused on developing the compensation method to decrease the errors in concave and convex surfaces milling processes through controlling the tool path. However, the solutions on solving the leading and trailing edges machining errors are lacking. This paper first utilizes the geometric modelling framework of the blade to solve the machining error compensation problem. Furthermore, the presented solution could be not only suitable for the concave and the convex surfaces milling processes, but also capable for decreasing the leading and the trailing edges machining errors. A novel geometric modelling of the blade is developed in this paper, including the reconstruction procedure of the concave and the convex curves based on the secant compensation method, and the construction strategy for the leading and trailing edges is derived through the design tangents of the leading and trailing edges points. The validation demonstrates that for the thin-walled part milling process, the proposed secant compensation method could decrease the machining errors significantly (the maximum and the average errors are reduced to 31.7% and 23.8%, respectively). And for the blade milling process, the average errors of concave and convex surfaces are reduced to 25.1% and 14.3%, respectively. The average errors of leading and trailing edges are reduced to 29.7% of uncompensated machining process.