The Construction Research Of Surface Defects Inspecting System For Small Pipes

Surface defects inside small bores in automotive cylinder could decrease workinglife and endanger driving safety. In recycle use surface defects must be conductedstrict testing. Most measurement techniques just fit for relatively large bores andmoreover, some testing methods for small bores have many disadvantages, such aslow level of automation. In order to overcome these shortages, this paper verifies akind method of machine vision for defects detection through constructing anexperimental system in laboratory condition.The paper focuses on the construction of detection system for surface defectsdetection inside small bores based on the principle of machine vision. Limited spaceof small bores disenables direct imaging process. The paper uses a special imagingand illumination part, sightpipe, making machine vision testing inside small borescome true. The combination of lighting path and imaging path within sightpiperesolves dimensional restriction problem inside small bores. Adaptive lighting systemis designed by PWM method to meet various circumstances demands with PIDalgorithm. The experimental system includes Electric displacement guide, Tilt table,rotating table, lift platform, measuring camera, etc. Coaxial alignments are quantifiedresearched and processes of adjustment are presented. The software is designed andeach part is discussed in detail. According to the characters of surface image, thepaper choices proper image processing methods based on OpenCV. The paper alsoanalyzes related factors which could result in measurement error and further putforward corresponding improving methods.The experimental system is developed and the automatic testing of surfacedefects could measure defects above0.3mm inside bores of8mm diameter,100mmdepth, reaching0.05mm standard deviation, which verifies the feasibility of follow-upin industrial application.