Estimation and compensation for continuous-path running trajectory error in high-feed-speed machining

Parts with rapidly varied geometric features are often key components in high-end equipment and are difficult to process because of the special structures and the strict requirements. Due to the existence of rapidly varied geometric features and the moving characteristic of continuous-path running, the trajectory error will be formed during machining process, which seriously restricts the machining accuracy of such parts. Additionally, the formative trajectory error is more non-ignorable in high-feed-speed machining. Existing studies can hardly reduce this error for arbitrary free-form trajectories without sacrificing of the machining efficiency. Consequently, aiming at reducing this error thus improving the processing efficiency and precision, the estimation and compensation methods for the trajectory error in high-feed-speed continuous-path machining are proposed. The actual reachable feed speed is recognized based on geometry and drive constraints of the numerical control (NC) machine tool. The continuous-path running trajectory error is estimated by approximating the desired toolpath with spline curves. The error compensation approach by combining the mirror compensation and the Taylor's expansion compensation is provided. The advantage of the proposed approach is that the continuous-path running trajectory error can be easily estimated and compensated only by analyzing and modifying the NC codes, which means an extensive feasibility for free-form toolpaths. Experimental results demonstrate the favorable performance of the proposed methods. This study provides an effective approach for reducing the multi-axis high-speed machining trajectory error and is significant for improving the machining precision and efficiency of the parts with rapidly varied geometric features in engineering.