三点法圆度测量精度分析

An Analysis on the Accuracy for Roundness Measurement with Three Point Method

详细分析了三点法中测头的读数及角位置误差对圆度测量精度的影响。从三点法的原理出发，根据误差理论，推导了测头及位置误差在圆度测量过程中的误差传播关系式。结果表明：三点法圆度测量结果失真的根本原因在于三个测头间的夹角选择不当，使测头读数误差在某些谐波上被大大放大。为提高三点法圆度测量精度，必须恰当选择三个测头间的夹角，以使读数误差对圆度各次谐波测量结果的影响都较小。

The effect of the reading errors and the angular misalignments of the probes on the accuracy for roundness measurement with three point method has been analyzed in detail in this paper.Based on the principle of three point method and error analysis theory,the error propagation equations of the reading errors and the angular misalignments of the probes in roundness measurement are derived.It is found that the root cause for the distortion of the roundness measured by three point method is the improper arrangement of the three probes' angular position which makes the reading errors over amplified at some harmonics of roundness.In order to improve the accuracy for roundness measurement by three point method,the angles between three probes must be optimized so that the effect of the reading errors and the angular misalignments on the accuracy for the measurements of all harmonics of roudness could be minimized.