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

Abstract

In the process of screw thread manufacturing, the cooling liquid or lubricating oil will adhere to the screw thread surface, which affects the vision measurement results of the screw thread parameters. To simulate the adhesion behavior of oil on the thread surface during the actual measurement, four different attachment states were set in this experiment. An image measuring instrument was used to collect the screw thread images of different adhesion states. Then, the distribution of the oil film on the screw thread surface was analyzed with computer image processing. The visual inspection method was used to obtain the relative influence rate of the oil adhesion on the measurement result of the screw thread parameters. Finally, an experiment-based pitch diameter compensation method was proposed, and the compensation effect of this method was verified with the test method. Experiments showed that the effect of oil adhesion on the measurement results of the diameter parameters is greater than 7 µm, and the effect on the measurement result of the thread angle is greater than 0.1°. The compensation experiment showed that the compensation efficiency was above 70% for the pitch diameter.

Compensation algorithm for taper thread distortion with large pitch and biased trapezoid

“…Both increased the thread accuracy from the viewpoint of image processing by improving the precision of thread image contour lines; however, the improvement was limited. Yang et al 22 . discovered that, during the thread production process, coolant or lubricating oil sticks to the thread surface, influencing the visual measurement findings of the thread parameters.…”

“…Both increased the thread accuracy from the viewpoint of image processing by improving the precision of thread image contour lines; however, the improvement was limited. Yang et al 22 discovered that, during the thread production process, coolant or lubricating oil sticks to the thread surface, influencing the visual measurement findings of the thread parameters. They then presented an experiment-based thread compensation approach to address the impact of coolant in the surrounding environment on the detection of thread parameters by analyzing the distribution of the oil layer on the thread surface.…”

Automatic Measurement of External Thread at the End of Sucker Rod Based on Machine Vision

“…Feng et al proposed the application of corner detection in thread vision measurement [ 4 ]. Yang et al discussed the effect of oil adhesion on the measurement of screw thread with machine vision and put forward the compensation method for the pitch diameter [ 5 ]. Lee et al used machine vision to develop an on-machine thread measurement system for computer numerical control lathe machines and verified the feasibility and accuracy of the on-machine external thread measurement system developed in this study [ 6 ].…”