Nihon Kikai Gakkai ronbunshu (Feb 2024)
Motion error estimation of circular arc interpolation cutter path of machining center produced by NC linear acceleration/deceleration processing
Abstract
From the machining center (MC) user’s point of view, this paper, as the second report of a systematic study, proposes a practical approach to estimate the trajectory error of a circular arc interpolation cutter path produced by the NC linear acceleration/deceleration (Acc/Dec) processing to interpolation segment and the feed axis servo control for a target MC. A simple and convenient motion model is established for describing the behavior of the servo axes corresponding to a circular arc segment of any length processed by the linear Acc/Dec operation. Based on the model and a linearity assumption on the dynamics of servo system, an efficient simulation method is developed to precisely calculate the cutter path trajectory and the servo axis speed from the motion parameters commanded in NC program. The verification experiments have been performed on the target MC, in which the specially designed cutter paths were inspected by a cross grid measuring device, and the measured motion trajectories were compared and discussed with the ones simulated by using the same motion parameters, from different perspectives. The examination results sufficiently demonstrate the effectiveness of the proposed model and simulation method if the adopted feed rate is within the commonly used range at the production site. Therefore, as a useful tool, the approach provides a potential application possibility, i.e. beforehand estimating the influence of the NC Acc/Dec processing and the servo control on cutter path accuracy or judging the motion conditions for the machining purpose without performing an actual machining with the target MC. Moreover, a reverse compensation principle of the cutter path motion error based on the simulation results is presented and examined through an actual example. The result has proved the possibility of practical application of the principle and suggested the direction of future effort.
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