Proceedings of the
9th International Conference of Asian Society for Precision Engineering and Nanotechnology (ASPEN2022)
15 – 18 November 2022, Singapore

Cornering Error Estimation of Look-Ahead Based Tool Path Generation Algorithm

Chan-Young Lee1,a, Seung-Kook Ro1, Chang Kyu Song1, Jeong Seok Oh1, Soon-Hong Hwang2 and Byung-Kwon Min2

1Department of Ultra-Precision Machines and Systems, Korea Institute of Machinery & Materials, Daejeon, 34103, South Korea

2Department of Mechanical Engineering, Yonsei University, Seoul, 03722, South Korea


Computerized numerical control (CNC) interpolator uses a look-ahead based tool path generation algorithm for high--speed and high-precision machining. The look-ahead algorithm of the CNC interpolator calculates an optimal velocity profile to utilize the maximum kinematic constraints of the machine tool feed drive. A corner smoothing algorithm is applied to the optimal velocity profiles to reduce the cycle time and smooth the tool path. The smoothed tool path causes a cornering error near the vertex. Because the cornering error decreases the dimensional accuracy of the workpiece, it is required to limit the error of the tool path. However, because the cornering error of the commercial CNC can be calculated using the actual tool path, it is difficult to limit the cornering error considering the machining accuracy before machining. This paper proposed a cornering error estimation algorithm for the CNC interpolator based on the look-ahead algorithm. A simulation model composed of the interpreter, velocity profiler, and interpolator was constructed to generate the smoothed tool path using the look-ahead algorithm. The cornering error estimation algorithm calculates the minimum distance between the smoothed tool path generated by the simulation model and the corner transition. The proposed algorithm was evaluated experimentally using the commercial CNC (0i-MD, Fanuc). The smoothed tool path was captured to calculate the actual cornering error of the commercial CNC using a monitoring program (Servo Guide, Fanuc). The cornering error estimated by the proposed algorithm was compared with experimental results to evaluate the estimation accuracy.

Keywords: Interpolation, Numerical Control Kernel, Precision machining

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