STEEL-PIPE SURFACE INSPECTION METHOD, SURFACE INSPECTION DEVICE, MANUFACTURING SYSTEM, DEFECT GENERATION-LOCATION SPECIFYING METHOD, AND MANUFACTURING METHOD

摘要

A control device 12 acquires a self-luminous image of a steel pipe captured when the steel pipe is hot, corrects the self-luminous image by uniformizing luminance variation in the circumferential direction of the self-luminous image, and detects a surface defect based on the corrected self-luminous image. The self-luminous image is preferably captured in a position behind a reducer. The diameter reduction rate applied by the reducer for the steel pipe is preferably equal to or greater than 110%. The luminance variation in the circumferential direction of the self-luminous image is uniformized by using a luminance distribution in the circumferential direction where the luminance in the longitudinal direction of the steel pipe is averaged. The luminance variation in the circumferential direction of the self-luminous image may be uniformized by using a difference in the luminance between a plurality of self-luminous images captured with the position in the longitudinal direction of the steel pipe changed.