基于自由曲面有向Voronoi区域划分算法的机器人加工刀轴低摆振路径规划
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摘要
针对自由曲面刀具路径规划中,刀轴摆动带来的振动影响加工质量的问题,提出有向Voronoi区域划分算法。基于该算法实现了刀轴运动优化的复杂自由曲面的区域划分,并光顺连接区域之间和区域内部的刀具路径,得到曲面整体实际可加工的刀具路径。应用该算法与UG不同路径规划的刀轴矢量变化进行了对比实验,结果显示刀轴矢量变化均值和累计值减少了30%,方差降低了近60,从而验证了该方法的刀轴矢量变化明显小于传统的对整个加工曲面的路径规划,可减小加工过程中的机械振动和冲击,保证加工刀轴姿态的稳定性,从而提高加工精度,减小对加工设备寿命的影响。利用工业机器人完成铣削实验,进一步验证了该方法的可行性和有效性。
To solve the problem of frequent large swing of tool axis in path planning of free-form surfaces, a Directed Voronoi Tessellation method(DVT) was proposed for dividing the surface. By connecting the outside and the inside of divided surface, the whole tool path which could really be machined was got. Compared with the control of UG with different path planning, the mean and cumulative variation of axis vector decreased around 30% and the variance was reduced by nearly 60%, which had verified the change of the tool axis vector of the proposed method was less than that of the traditional machining surface, and could reduce the mechanical vibration and impact in the process. Thus the stability of the shaft attitude was conducive to improving the processing accuracy and reduce the impact on the life of the processing equipment. The milling experiment was completed with the industrial robots, and the results further confirmed the feasibility and effectiveness of the method.
To solve the problem of frequent large swing of tool axis in path planning of free-form surfaces, a Directed Voronoi Tessellation method(DVT) was proposed for dividing the surface. By connecting the outside and the inside of divided surface, the whole tool path which could really be machined was got. Compared with the control of UG with different path planning, the mean and cumulative variation of axis vector decreased around 30% and the variance was reduced by nearly 60%, which had verified the change of the tool axis vector of the proposed method was less than that of the traditional machining surface, and could reduce the mechanical vibration and impact in the process. Thus the stability of the shaft attitude was conducive to improving the processing accuracy and reduce the impact on the life of the processing equipment. The milling experiment was completed with the industrial robots, and the results further confirmed the feasibility and effectiveness of the method.
引文
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[2] WU Guanglin,NI Jimin.Method for generating interference-free tool path for real-time surface interpolation[J].Chinese Journal of Mechanical Engineering,2001,37(5):93-96(in Chinese).[吴光琳,倪基民.曲面实时插补无干涉刀轨的生成方法[J].机械工程学报,2001,37(5):93-96.]
[3] YIN Z,JIANG S.Iso-phote based adaptive surface fitting to digitized points and its applications in region-based tool path generation,slicing and surface triangulation[J].Computers in Industry,2004,55(1):15-28.
[4] CHEN Liangji,CHENG Junwei,WANG Yongzhang.Tool path generation algorithm for five-axis NC machining with a toroidal cutter[J].Chinese Journal of Mechanical Engineering,2008,44(3):205-212(in Chinese).[陈良骥,程俊伟,王永章.环形刀五轴数控加工刀具路径生成算法[J].机械工程学报,2008,44(3):205-212.]
[5] CHEN Z C,SONG Dejun.A practical approach to generating accurate iso-cusped tool paths for three-axis CNC milling of sculptured surface parts[J].Journal of Manufacturing Processes,2006,8(1):29-38.
[6] HWANG J S,CHANG T C.Three-axis machining of compound surfaces using flat and filleted endmills [J].Computer-Aided Design,2008,30(8):641-647.
[7] CHOI B K,JUN C S.Ball-end cutter interference avoidance in NC machining of sculptured surfaces [J].Computer Aided Design,2009,21(6):371-378.
[8] CHEN Z C,FU Qiang.A practical approach to generating steepest ascent tool-path for three-axis finish milling of compound NURBS surfaces[J].Computer-Aided Design,2007,39(11):964-974.
[9] WANG Qirui,FENG Yixiong,ZHANG Zixian,et al.Toroidal cutter tool path generation method on triangular mesh surface based on modified butterfly subdivision[J].Computer Integrated Manufacturing Systems,2016,22(11):2513-2521(in Chinese).[王琪瑞,冯毅雄,张子贤,等.基于改进型Butterfly细分的三角网格自由曲面环形刀具轨迹规划[J].计算机集成制造系统,2016,22(11):2513-2521.]
[10] JEONG J,KIM K.Tool path generation for machining free-form pockets using voronoi diagrams[J].Advanced Manufacturing Technology,1998,14(12):876-881.
[11] HINDUJA S,MANSOR M S A,OWODUNNI O O.Voronoi-diagram-based linking of contour-parallel tool paths for two-and-a-half-dimensional closed-pocket machining[J].Proceedings of the Institution of Mechanical Engineers,Part B:Journal of Engineering Manufacture,2010,224(9):1329-1350.
[12] MOHAMMED L A,AL-KINDI G A,KADHIM M J.Voronoi diagram based offset paths for NC[J].Journal of Engineering and Technology,2003,22(2):1-8.
[13] YAN Bing,LIU Bibo,DENG Zhiyun,et al.Tool path generation for pockets bounded by free-form curves based on the voronoi diagram[J].Journal of Computer Aided Design & Computer Graphics,1999,11(1):66-69(in Chinese).[闫兵,刘碧波,邓志云,等.基于Voronoi图理论的自由边界型腔加工路径规划[J].计算机辅助设计与图形学学报,1999,11(1):66-69.]
[14] CHEN Song,LI Xueyi.Contour-parallel tool-path planning of free-form surface[J].Journal of Computer Aided Design and Computer Graphics,2002,14(11):1032-1035(in Chinese).[陈松,李学艺.自由曲面环切刀位规划[J].计算机辅助设计与图形学学报,2002,14(11):1032-1035.]
[15] ZHANG Rui.Study on surface machining trajectory planning method based on milling force control[D].Harbin:University of Science and Technology,2016(in Chinese).[张芮.基于铣削力控制的曲面加工路径规划方法研究[D].哈尔滨:哈尔滨理工大学,2016.]
[16] XIAO Wenlei,HUAN Ji.Integration of a cutting robot with CAD/CAM system[J].Chinese Journal of Mechanical Engineering,2011,47(15):52-60(in Chinese).[肖文磊,郇极.切削加工机器人与CAD/CAM系统集成化[J].机械工程学报,2011,47(15):52-60.]