Research on Screw Thread Form Based on Non-Contact Measurement

Abstract

There is a problem with non-contact measurement and detection, which reduces its measurement accuracy. Methods developed for measuring and inspecting screw thread characteristic parameters usually using a camera, which is controlled to scan the projection of thread in the parallel optical field to obtain thread images. However, with the block of screw line on the projection of the real thread form, it is impossible to acquire the real thread form from images. The traditional way is adjusting the optical axis to a suitable angle with the thread axis to acquire the real thread form projection, which has some problems, such as time consuming, high skill of operator, high-precision equipment for adjustment, inaccuracy, and so on. Hence, a new method through digital image calibration is presented. The results of relevant simulation indicated the feasibility of this new method, which improves thread measurement and detection accuracy.

Development of a measuring system for the diameter of a smooth plug gauge based on machine vision technology

“…8 In many measuring systems which used the machine vision technology, it measures accurate data by acquiring the overall image which has high requirements on the performance of the imaging equipment and poor economy. [9][10][11] A kind of image measuring instrument is studied in this paper. It only needs to calibrate the system once to achieve long-term measurement, and there is no human error, and it has very low requirements for the operator.…”

Improved Particle Swarm Optimization Algorithm Based on a Three-Dimensional Convex Hull for Fitting a Screw Thread Central Axis

“…At present, in 3D measurement, the method of determining the central axis of thread gauge still relies on the experience of the engineer to manually adjust, which not only increases the difficulty of subsequent measurement, but also increases the uncertainty of measurement results. In recent years, with the implementation of major instrument science and equipment development projects, it is very necessary to design a method that can quickly and accurately fit the central axis of the thread [2].…”

Effect of oil adhesion on the measurement of screw thread with machine vision

“…Chen 7 proposed a compensation method for thread profile distortion that had a pitch diameter compensation effect of more than 85% and a thread angle compensation effect of more than 70%. Shen et al 8 analyzed the problem of thread profile distortion during the machine vision measurement and provided a compensation method. Despite the many achievements in screw thread vision measurement, there have been a few studies on the effect of oil adhering to a screw thread surface using visual measurements.…”