Feeding strategy optimization for a blisk with twisted blades in electrochemical trepanning

Abstract

Blisk manufacturing generally involves two steps in electrochemical machining, namely roughing and finishing, with the aim of the former being to form the blade blank with an allowance that is as uniform as possible. This paper focuses on improving the allowance uniformity in the roughing stage of blisk. Electrochemical trepanning (ECTr) is an effective roughing method. To homogenize the allowance distribution of twisted blades on a blisk in ECTr, this paper proposes a cathode-rotating feeding strategy that involves both a constant rotation rate and a variable one. To examine how those two modes differ, kinematic simulations are performed. To determine the optimal rotation feeding trajectories, under the established parametric model, an evaluation criterion based on the minimum value among the maximum allowance differences (MADs) is proposed and adaptive particle swarm optimization intelligent algorithm is adopted. For a twisted blade with varying cross section, the feeding trajectories of the two modes are calculated and simulated. Under constant-rotation-rate feeding, the values of the MAD for the predicted blade are 1.478 mm and 1.432 mm at the concave and convex parts, respectively. The values of MAD are reduced to 0.849 mm and 0.961 mm, respectively, under variable-rotation-rate feeding, and the uniformities of the allowance distributions are improved by 42.6 % and 32.9 %, respectively. The experiment of cathode-rotating feeding ECTr with variable rotation rate was performed. For the machined blade, the values of MAD at the concave and convex parts are 0.955 mm and 0.786 mm, respectively. The deviations between the experiments and simulations are 11.1 % and 18.2 %, respectively, thereby showing the optimization method to be effective.