Aiming at the difficulties in toolpath planning and machining accuracy achievement in free-surface flank milling, this paper proposes a method for designing the tool contour of freeform generatrix. While optimizing the tool contour, this method fully considers the workpiece accuracy and tool axis smoothness during machining, thereby realizing the tool contour design and the flank milling path planning. This study first evaluates the machining error by calculating the interference between tool and workpiece on the cutting line after respectively defining the tool contour generatrix and tool axis trajectory surface to express the tool shape and flank milling path. The tool axis smoothness is also evaluated by tool axis trajectory energy, and a simultaneous optimization model of tool contour and machining trajectory based on the machining error and tool axis smoothness is established. Secondly, to solve the simultaneous optimization model, a solution strategy based on the successive approximation method is presented, and the method for acquiring the control parameters of the tool axis trajectory surface and the tool contour control parameters in the initial values are also provided. Finally, the path planning experiment and tool contour design experiment are designed respectively, verifying the correctness and effectiveness of the algorithm in the tool contour design and path optimization for 4-axis flank milling of freeform surface proposed in this paper. This research provides an effective method for both accuracy improvement in flank milling of freeform surface parts and realization of the tool contour design and path planning of flank milling.
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