A surface inspection system for hot-rolled strip steel was developed independently to meet the urgent needs for detection of surface defects of hot rolled strip steel.This system was designed based on the machine vision technology,using line-scan CCD cameras as surface image acquisition devices.A super bright LED light was developed independently,which can solve the problem of inhomogeneous illumination from a long distance at a high temperature.The high-efficiency image-processing and objects-recognizing algorithms are used in the system so as to guarantee the real-time image processing and precise recognition of the surface defects.The eight monthes on-line operation proves that the system has a higher accuracy for defect detection and classification,together with real time and reliability.

As an important part of the inspection system,a light source in normal condition is the basic guarantee of the system.In a high temperature environment,if the light is too close to the strip steel,the light will be damaged by the radiation and convection,and if the light is far from the strip steel,the illumination will be unable to satisfy the requirements.Therefore,how to control the light surface temperature and make the light in a reasonable distance range in a high temperature environment will be the key in the light source design.In this paper,the relationship between the light source distance,thermal radiation received by the light source and the illumination was analyzed.The light source which is suitable to the hot strip surface inspection has been designed.The application of the light source at the worksite has proved that the design method is correct.