Experimental study on quantitative surface defect depth detection based on laser scanning technology in continuous casting

Abstract

In this paper, a scanning laser system based on an array couple charged detector (CCD) has been developed to detect and measure quantitatively the morphology and depth of defects on continuously cast billet (CC billet) surface at high temperatures. The technique, based on a linear light scattering method, employs a low power He-Ne laser and a conventional CCD probe and enables a narrow line array laser beam to be projected on the test surface across the width direction on the CC billet surface. In the relative scanning direction between the test surface and the CCD probe, the one-dimensional linear surface image acquired by the CCD sensor at a given shutter time, which exhibits the curvature change of the laser scanning line, can be used to determine the distance morphology according to triangulation principles. Combining with casting speed, a linear laser beam image can be spliced into a two-dimensional surface image that constructs the billet surface profile and detects surface defect shape and depth. Furthermore, it can reconstruct a threedimensional morphology for the billet surface defects in the high temperature condition. Proof of concept experiments have been performed through online measurement of different size defects, and quality tracking on the hot CC billet surface has been implemented.

A Deep-Learning-based 3D Defect Quantitative Inspection System in CC Products Surface

“…Machine vision (MV) in NDE combined with AI algorithms is becoming a burgeoning method which can perform with a fast response, a high signal-to-noise ratio and a strong anti-jamming capability [10,11] compared with ultrasonic, eddy current and other contact methods. The MV merits make it more competitive in harsh environment application like CC manufacturing field [12,13]. On the other hand, MV-based 3D optical metrology has gradually demonstrated superiority, such as [14][15][16] stereoscopy triangulation (mm), interferometry (nm), con-focal vertical scanning, and fringe projection (um).…”

A double laser filtering approach to vibration noise rejection for hot-rolled strip flatness measurement

“…Kalman filtering algorithm has the features of small calculation, easy to realise the programme and good filtering effect, etc. It is widely used in the fields of astronomy [6], spaceflight [7,8], multi-sensor information fusion [9], sensor networks [10], etc. Under the condition that the coefficient and variance of system are given, it has many achievements about stability and convergence of the algorithm [11].…”

Simulation and detection of flaws in pre-cured CFRP using laser displacement sensing

“…Laser displacement sensing (LDS) is widely used to measure the geometrical dimensions of test specimens, where a point or line laser signal is projected on the object and the reflected or scattered signal is processed [4]. LDS has a wide range of application in industry [4][5][6][7][8] as these sensors are used in robotics, autonomous vehicles, anti-collision and proximity sensors. The sensors are also used in industrial manufacturing to monitor the quality in automatic line production, such as a vision inspection sensor system for the automation of laser welding processes in heavy industries.…”