| 摘要 |
PURPOSE: To realize diversified detection and identification of flaw on the surface of a steel pipe by combining the advantages of light-section and reflection systems. CONSTITUTION: A laser slit light 16 is reflected 2 and irradiates an objective surface 3a such that a steel pipe 3 moving in the axial direction thereof is sliced obliquely thus producing a light-section profile 17. The reflected light 16a is received 14 and constitute a part of a continuous ellipse but it is discontinuous at level difference part, i.e., a flaw part 18. It is then subjected to A/D conversion through a light-section controller 5 and inputted 6 as a profile signal having two-dimensional coordinate. If a measured flaw/level difference signal is higher than a threshold, it is identified as a surface flaw/level difference having continuity in the axial direction of pipe. Subsequently, regular and diffuse reflection illuminators 7, 8 mounted on the outer surface of a steel pipe 3 turnable through a turning roll 9 are lighted alternately and the reflected light is received 10 and subjected to A/D conversion thus producing a pattern signal of two-dimensional lightness. It is subjected to image processing 14, 15 to produce a flaw signal and when it is higher than a threshold value, it represents a surface flaw discontinuous in the longitudinal direction. |
