A G3 continuous five-axis tool path corner smoothing method with improved machining efficiency and accurately controlled deviation of tool axis orientation

• Published in: International journal of advanced manufacturing technology Vol. 119; no. 11-12; pp. 7003 - 7024
• Main Author: Sun, Shujie
• Format: Journal Article
• Language: English
• Published: London Springer London 01.04.2022; Springer Nature B.V
• Subjects: Acceleration; CAE) and Design; Chords (geometry); Computer-Aided Engineering (CAD; Contouring; Deviation; Discontinuity; Efficiency; Engineering; Five axis; Free form; Industrial and Production Engineering; Kinematics; Machine shops; Machine tools; Machining; Machining centres; Mechanical Engineering; Media Management; Numerical controls; Orientation; Original Article; Segments; Smoothing; Synchronism; Tracking errors; continuity; Corner smoothing; Bezier spline; Optimized curvature; Five-axis; G
• ISSN: 0268-3768; 1433-3015
• DOI: 10.1007/s00170-021-08227-4

Parts with free-form surfaces are machined by connecting short linear tool path segments on five-axis computer numerical control (CNC) machining centers. Discontinuities at the junctions of linear segments reduce the machining efficiency, leave marks on the finish surfaces, and cause higher tracking errors, hence leading to larger contouring errors. This paper aims to improve the machining efficiency and accuracy of previously presented G 3 continuous tool path smoothing method for 5-axis CNC machining (Sun and Altintas in CIRP J Manuf Sci Tec 32:529–549, [ 8 ]). Compared with the previous work, this paper improves the machining efficiency by optimizing the maximum feedrate along the transition splines while respecting the corner transition error tolerance, chord error tolerance, and tangential kinematic limits (i.e., the feedrate command, tangential acceleration, and jerk limits) at the connection points or “corners”. To improve the machining accuracy, this paper takes the maximum feedrate allowed on the tool tip position spline as one of the constraints to keep the path deviation of tool axis orientation within the tolerance when the tool axis orientation is smoothed. In the paper, the bottom tool path segments are first smoothed by Bezier spline with an optimized feedrate while respecting corner error tolerance and tangential kinematic limits. Then, the top tool axis orientation path segments are smoothed with additional feedrate synchronization constraint. At last, the tool axis orientation and tool tip positions are synchronized to avoid discontinuous displacements along the tool axis, and the maximum feedrate allowed on the bottom corner transition spline would be further limited when the bottom or top corner transition spline is revised. The effectiveness of the proposed method to smoothen the five-axis tool paths have been demonstrated with simulations and experiments.