Research on Machine Vision Based Thread Parameter Compensation Algorithm

In order to study the influence of thread tooth shading on the measurement accuracy of thread parameters, a compensation algorithm based on machine vision for thread tooth angle and median diameter is proposed based on the analysis of existing methods for calculating the amount of thread tooth distortion. The threaded annular groove without screw-up angle is compared with the image of the threaded plug gauge with screw-up angle to obtain the compensation amount of the thread tooth angle, and then the compensation amount of the corresponding thread tooth mid-diameter is found according to the compensation amount of the tooth angle, and finally the compensation of the thread parameters is realized. The data show that the average value of 59.999° and 18.290 mm of median diameter compensation obtained by the proposed method is close to the average value of 60.015° and 18.326 mm of median diameter measured by the contact thread gauge, and the variance of
$7.76\times 10^{-5}$
and
$8.65\times 10^{-5}$
of median diameter variance after compensation. The variance of
$7.76\times 10^{-5}$
and
$8.65\times 10^{-4}$
of the mid-diameter are smaller than the variance of the tooth angle and mid-diameter measured by the integrated measuring instrument. The results show that the compensation algorithm proposed in this paper is feasible.