샤프트 표면결함 검출을 위한 비전검사 시스템 개발

The quenched and tempered steel is usually treated by heat treatment. But micro-alloyed steel including alloying elements such as vanadium, boron and so on is applied without overall heat treatment. The surface of crankshaft made with micro-alloyed steel is locally processed by induction hardening. The process can cause a crack on grinded surfaces when residual tensile stress is higher than strength of the material. Therefore crack inspection is required. Various inspection methods such as magnetic testing and eddy current testing have been used for detecting surface defects of shaft in automobile engine and transmission. Magnetic testing is to see fluorescent lines by condensed magnetic particles on defects and can have an error because of worker’s subjective judgment. Eddy current testing is difficult to be flexible because it should have many sensors to detect surface defects. Also, it has limitation in detection ability because the higher sensor sensitivity is the more noise is included. The eddy current sensor can detect cracks above a depth of 0.1mm. In this paper, it is investigated that vision inspection method is valid in ability of detection, classification, measurement of surface defects such as crack, contamination, scratch, and pores.