A contouring error prediction and compensation method for a blisk machining center

The aero-engine blisk has large size and complex structure, leading to drastic variations in driving axis speed during machining process, which brings a critical challenge for efficient and stable contouring error control. Pure trajectory planning fails to perfectly smooth the variation of speed due to the complex structure of blisk. Additionally, advanced controllers often reduce the stability of control systems, limiting their application in commercial Computer Numerical Control (CNC) machine tools. To address these problems, this paper proposes an effective and practical contouring error prediction and compensation method for a blisk machining center. First, the tracking error of driving axis is accurately calculated to overcome the time delay in feedback. Subsequently, the contouring error is predicted combining the tracking error of driving axis with the geometrical structure of blisk machining center. In terms of contouring error compensation, speed feedforward compensation is employed to enhance the tracking performance of driving axis, while command modification is applied to further improve contouring accuracy without affecting system stability. Based on the experimental results, the tracking error of driving axis and contouring error achieve high prediction accuracy with the deviations of average values below 6.49 % and 12.41 % under three different motion conditions, respectively; moreover, the contouring error of the sample trajectory is reduced to the micron level after speed feedforward compensation, and further decreased more than 32.85 % through command modification. A typical blisk sample is finally machined successfully, validates the effectiveness and practicability of the proposed method.