5-axis Tool Path Smoothing Based on Drive Constraints

In high speed machining, the real feedrate is often lower than the programmed one. This reduction of the feedrate is mainly due to the physical limits of the drives, and affects machining time as well as the quality of the machined surface. Indeed, if the tool path presents sharp geometrical variations the feedrate has to be decreased to respect the drive constraints in terms of velocity, acceleration and jerk. Thus, the aim of this paper is to smooth 5-axis tool paths in order to maximize the real feedrate and to reduce the machining time. Velocity, acceleration and jerk limits of each drive allow to compute an evaluation of the maximum reachable feedrate which is then used to localize the areas where the tool path has to be smoothed. So starting from a given tool path, the proposed algorithm iteratively smoothes the joint motions in order to raise the real feedrate. This algorithm has been tested in 5-axis end milling of an airfoil and in flank milling of an impeller for which a N-buffer algorithm is used to control the geometrical deviations. An important reduction of the measured machining time is demonstrated in both examples.

[1]  Christophe Tournier,et al.  Kinematical performance prediction in multi-axis machining for process planning optimization , 2008 .

[2]  Christophe Tournier,et al.  Optimization of 5-axis high-speed machining using a surface based approach , 2008, Comput. Aided Des..

[3]  Pascal Ray,et al.  The Domain of Admissible Orientation concept: A new method for five-axis tool path optimisation , 2008, Comput. Aided Des..

[4]  Kang G. Shin,et al.  Minimum-time control of robotic manipulators with geometric path constraints , 1985 .

[5]  Yean-Ren Hwang,et al.  Five-axis tool orientation smoothing using quaternion interpolation algorithm , 2003 .

[6]  Christian Brecher,et al.  Virtual machine tool , 2005 .

[7]  Yusuf Altintas,et al.  High speed CNC system design. Part I: jerk limited trajectory generation and quintic spline interpolation , 2001 .

[8]  Pierre-Yves Pechard,et al.  Geometrical deviations versus smoothness in 5-axis high-speed flank milling , 2009 .

[9]  Jiing-Yih Lai,et al.  On the development of a parametric interpolator with confined chord error, feedrate, acceleration and jerk , 2008 .

[10]  J. Bobrow,et al.  Time-Optimal Control of Robotic Manipulators Along Specified Paths , 1985 .

[11]  Richard P. Paul,et al.  Robot manipulators : mathematics, programming, and control : the computer control of robot manipulators , 1981 .

[12]  Olivier Gibaru,et al.  Feedrate planning for machining with industrial six-axis robots , 2010 .

[13]  Pascal Ray,et al.  Corner optimization for pocket machining , 2004 .

[14]  Elizabeth A. Croft,et al.  Feed optimization for five-axis CNC machine tools with drive constraints , 2008 .

[15]  Robert B. Jerard,et al.  Methods for detecting errors in numerically controlled machining of sculptured surfaces , 1989, IEEE Computer Graphics and Applications.

[16]  Didier Dumur,et al.  High-performance NC for high-speed machining by means of polynomial trajectories , 2004 .

[17]  Allan D. Spence,et al.  A constant feed and reduced angular acceleration interpolation algorithm for multi-axis machining , 2001, Comput. Aided Des..

[18]  Michele Heng,et al.  Design of a NURBS interpolator with minimal feed fluctuation and continuous feed modulation capability , 2010 .

[19]  Pierre Bourdet,et al.  A new format for 5-axis tool path computation, using Bspline curves , 2004, Comput. Aided Des..

[20]  Yuan-Shin Lee,et al.  Optimizing tool orientations for 5-axis machining by configuration-space search method , 2003, Comput. Aided Des..

[21]  Walter Rubio,et al.  Kinematic modelling of a 3-axis NC machine tool in linear and circular interpolation , 2010, ArXiv.