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Integrated post-processor for 5-axis machine tools with geometric errors compensation |
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| Affiliation: | 1. Georgia Institute of Technology, George W. Woodruff School of Mechanical Engineering, Atlanta, GA, USA;2. Georgia Institute of Technology, College of Engineering, Atlanta, GA, USA;3. Georgia Institute of Technology, Department of Computer Science, Atlanta, GA, USA;4. Shanghai Jiao Tong University, School of Mechanical Engineering, Shanghai, China;5. Tucker Innovations, Inc., Charlotte, NC, USA;1. Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education, Tianjin University, Tianjin 300072, China;2. School of Engineering, The University of Warwick, Coventry CV4 7AL, UK;1. College of Mechanical and Electrical Engineering, Hunan University of Science and Technology, Xiangtan, Hunan, 411201, China;2. State key laboratory of High-performance Complex Manufacture, Central South University, Changsha, Hunan 410083, China;1. State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, PR China;2. Hubei Key Laboratory of Waterjet Theory and New Technology, Wuhan University, Wuhan, 430072, PR China |
| Abstract: | Geometric errors of 5-axis machine tools introduce great deviation in real workpiece manufacture and on-machine measurement like touch-trigger probe measurement. Compensation of those errors by toolpath modification is an effective and distinguished method considering the machine calibration costs and productivity. Development of kinematic transformation model is involved in this paper to clarify the negative influences caused by those errors at first. The deviation of the designed toolpath and the real implemented toolpath in workpiece coordinate system is calculated by this model. An iterative compensation algorithm is then developed through NC code modification. The differential relationship between the NC code and the corresponding real toolpath can be expressed by Jacobi matrix. The optimal linear approximation of the compensated NC code is calculated by utilizing the Newton method. Iteratively applying this approximation progress until the deviation between the nominal and real toolpath satisfies the given tolerance. The variations of the geometric errors at different positions are also taken into account. To this end, the nominal toolpath and the geometric errors of the specific 5-axis machine tool are considered as the input. The new compensated NC code is generated as the output. The methodology can be directly utilized as the post-processor. Experimental results demonstrate the sensibility and effectiveness of the compensation method established in this study. |
| Keywords: | Geometric error Kinematic model Jacobi matrix Iterative compensation |
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