Conversion method study from cutter-location points to nonuniform rational B-spline toolpath NC file for high-speed machining

Abstract

Parts with complex curved surfaces are widely applied and the demands for the machining quality and the machining efficiency of such complex parts become increasingly higher. In order to realize high-speed and high-quality machining, the nonuniform rational B-spline interpolator is widely researched and demonstrated to be superior to the conventional linear or circular interpolators. However, the nonuniform rational B-spline toolpath NC files cannot be directly generated from the computer-aided design (CAD) models by using commercial computer-aided manufacturing (CAM) software. To deal with this problem, a conversion method from the cutter-location points to the nonuniform rational B-spline toolpath numerical control (NC) file is presented. To avoid the bad curve-fitting effect at sharp corners of the toolpath and to meanwhile reduce the computational burden, the cutter-location pre-processing method, consisting data segmentation and data simplification, is provided first. Then, the least-square method is employed to fit the cutter locations to the nonuniform rational B-spline curves, and an iterative fitting approach is proposed for linear/nonuniform rational B-spline hybrid toolpath generation. Finally, a user interface is designed for displaying the fitting results and outputting the NC file with nonuniform rational B-spline toolpaths. By using this method, nonuniform rational B-spline and linear toolpaths hybrid interpolation NC program can be generated for the high-speed machining of complex curved surface parts with the utilization of the nonuniform rational B-spline interpolator. The experimental results demonstrate the feasibility and the advantages of the presented method.

Keywords

Nonuniform rational B-spline toolpath parametric curve interpolation curve fitting high-speed machining complex curved surface cutter-location points

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References

Khalick

MAE

Uchiyama

. Discrete-time model predictive contouring control for biaxial feed drive systems and experimental verification. Mechatron 2011; 21: 918–926.

Heng

Erkorkmaz

. Design of a NURBS interpolator with minimal feed fluctuation and continuous feed modulation capability. Int J Mach Tools Manuf 2010; 50: 281–293.

Sencer

Ishizaki

Shamoto

. A curvature optimal sharp corner smoothing algorithm for high-speed feed motion generation of NC systems along linear tool paths. Int J Adv Manuf Technol 2015; 76: 1977–1992.

Dong

Wang

et al.

Smooth feedrate planning for continuous short line tool path with contour error constraint. Int J Mach Tools Manuf 2014; 76: 1–12.

Liu

Huang

Yin

et al.

Development and implementation of a NURBS interpolator with smooth feedrate scheduling for CNC machine tools. Int J Mach Tools Manuf 2014; 87: 1–15.

Annoni

Bardine

Campanelli

et al.

A real-time configurable NURBS interpolator with bounded acceleration, jerk and chord error. Comput-Aided Desi 2012; 44: 509–521.

Lai

. Tool-path generation of planar NURBS curves. Robot Comput-Integr Manuf 2010; 26: 471–482.

Feng

Wang

et al.

Design of a real-time adaptive NURBS interpolator with axis acceleration limit. Int J Adv Manuf Technol 2010; 48: 227–241.

Lin

Tsai

Yau

. Development of a dynamics-based NURBS interpolator with real-time look-ahead algorithm. Int J Mach Tools Manuf 2007; 47: 2246–2262.

10.

Kruth

. NURBS curve and surface fitting for reverse engineering. Int J Adv Manuf Technol 1998; 14: 918–927.

11.

. NURBS curve fitting based on arc centripetal parameterization for tool path generation. Appl Mech Mater 2013; 274: 121–123.

12.

Yang

Shen

Yuan

et al.

Curve fitting and optimal interpolation for CNC machining under confined error using quadratic B-splines. Comput-Aided Des 2015; 66: 62–72.

13.

Lin

Ueng

Lai

. CNC codes conversion from linear and circular paths to NURBS curves. Int J Adv Manuf Technol 2008; 39: 760–773.

14.

Zhou

Tang

et al.

Implementation of CL points preprocessing methodology with NURBS curve fitting technique for high-speed machining. Comput Ind Eng 2015; 81: 58–64.

15.

Lin

. Adaptive data fitting by the progressive-iterative approximation. Comput Aided Geom Des 2012; 29: 463–473.

16.

Deng

Lin

. Progressive and iterative approximation for least squares B-spline curve and surface fitting. Comput-Aided Des 2014; 47: 32–44.

17.

Garcia-Capulin

Cuevas

Trejo-Caballero

et al.

A hierarchical genetic algorithm approach for curve fitting with B-splines. Genet Program Evolvable Mach 2015; 16: 151–166.

18.

Liang

Zhao

et al.

A novel knot selection method for the error-bounded B-spline curve fitting of sampling points in the measuring process. Meas Sci Technol 2017; 28: 065015–065015.

19.

Dung

Tjahjowidodo

. A direct method to solve optimal knots of B-spline curves: an application for non-uniform B-spline curves fitting. Plos One 2017; 12: e0173857–e0173857.

20.

Piegl

Tiller

. The NURBS Book, 2nd ed. Berlin, Heidelberg: Springer, 1997.