Aiming at roundness error evaluating, this paper introduces a fast and accurate method of searching center of minimum zone circle(MZC). In order to evaluate roundness error accurately, evaluation mechanism of minimum zone circle for roundness error is studied, and an evaluation model of measuring &computing based on the intersecting chord is established, to get a search method for feature points by relative change of chord length. Through chord' s twice transform relationships of inscribed circle and circumscribed circle, the virtual center which is produced by the intersecting chord can determine the "2 +2"characteristic model of M ZC accurately. As a result, the alogorithm of using geometrical symmetry of intersecting chord to quickly evaluate roundness error is obtained, which means making the evaluation more accurate and reliable. The analysis data and results indicate that the algorithm has high computing speed and evaluating precision, thus providing a new strategy and means for roundness error evaluation.%针对圆度误差的评价方法,介绍一种利用最小区域法评价圆度误差的计算方法.研究最小区域圆度误差评价机理,建立基于弦线截交关系的最小区域圆度误差评价模型,并得出了利用弦线相对变化搜索特征点的方法.通过内、外接圆的两次弦线变换关系,利用弦线变换产生的虚拟中心可以准确确定最小区域圆的"2+2"特征关系,达到了快速、精确利用最小区域法评价圆度误差的目的.通过分析表明,基于弦线截交关系的最小区域圆度误差评价方法计算效率高、易于实现且具有较高的评定精度,也为圆度误差评价提供一种新的方法和思路.
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