Abstract

This paper presents an analytical continuous smoothing method for the five-axis toolpath by simultaneously scheduling the tool position and tool orientation trajectories. In order to ensure the high-order continuous, the peak-controlled jerk and arclength-parameterized property, a novel curve “airthoid” is proposed for the first time. The biairthoid is involved to smooth the corners of the tool position in the workpiece coordinate system (WCS) and the corners of the tool orientation in the machine coordinate system (MCS), the geometries of which are analytically determined by the user-defined deviation errors. A time synchronization strategy is proposed to extend the duration of the predetermined cubic acceleration profile to a specified time. With the kinematic constraints of the tool position and the tool orientation, the transitional and rotational trajectories are analytically synchronized by sharing the same motion time. To comply with the constraints of the linear feed drives, an optimization strategy is conducted by adjusting the kinematics of the tool position. By doing so, the approximation errors of the tool position and tool orientation in the WCS are strictly satisfied. The analytical arclength expression of the smoothing curves is more suitable for the on-line interpolation. Due to the arclength-parametrized transition curve, the feedrate fluctuation is eliminated. With the proposed time synchronization strategy, the physical limits of the feed drives are all respected. Moreover, the high-order continuous airthoid makes the motion more smoothing-going. Simulations and experiments verify the effectiveness of the proposed algorithm.

Highlights

  • Five-axis machine tools are widely adopted to machine free-form parts due to the graceful advantages in the cutting efficiency and machining reachability

  • The parametric curve is usually discretized as the linear segments under the predefined tolerance, and segments are programmed as G01 commands [5]

  • In the previous researches [10]–[14], the feedrate profile of the tool position is established on the basis of the transitional kinematic constraints, and the tool orientation path was treated as the slave motion scheduled by the parameter synchronization

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Summary

INTRODUCTION

Five-axis machine tools are widely adopted to machine free-form parts due to the graceful advantages in the cutting efficiency and machining reachability. Researchers usually smooth 5-axis linear paths by inserting two different parametric splines to attain the geometric high-order continuity, and at the same time, to guarantee the subspline parameters synchronization. In the previous researches [10]–[14], the feedrate profile of the tool position is established on the basis of the transitional kinematic constraints, and the tool orientation path was treated as the slave motion scheduled by the parameter synchronization. To simultaneously obtain the real-time high-order continuous interpolation and respect both the kinematic constraints of the tool position and tool orientation paths, this paper proposes a novel continuous smoothing method based on the airthoid curves for the five-axis machining toolpath.

AIRTHOID SPLINE
THE ANALYTICAL CORNER SMOOTHING OF THE TOOL ORIENTATION
15 Vd td4 t
TIME SYNCHRONIZATION
REAL-TIME LOOKAHEAD SCHEDULING BASED ON THE TIME SYNCHRONIZATION
SIMULATION
VIII. CONCLUSION
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