Experimental study of surface defects in continuous casting using developed laser scanning system

Abstract

Various methods of detecting surface defects are being used in automated industrial manufacturing environments. This work presents the design and development of a laser charged couple device (CCD) displacement scanning system. The surface defect detection method using a laser CCD displacement sensor is derived from an idea in which surface defects such as cracks, inclusions and holes of three-dimensional morphology characteristics are compared to normal surface especially in continuous casting slabs. Some novel research methods have been applied to develop the surface defect detection system used: first, getting a one-dimensional distance matrix along transverse direction and a two-dimensional matrix combining with a certain moving speed through the laser CCD displacement sensor; second, obtaining the slab surface profile and mapping to a greyscale image and finally, obtaining the surface defect regions by an image processing and searching algorithm and quantitatively detecting slab surface defect shape and depth. The research results in the lab trials have shown that the methodology proposed is effective to detect two-dimensional defect size and reconstruct a three-dimensional surface defect shape. At the same time, it is also able to accurately locate and identify surface defects and realise automatic surface defect non-destructive detection online, and provides a theoretical base and technology idea for further studying surface defects online inspection for hot continuous casting slab.

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

“…Although the technical objectives to be improved have been identified, no manufacturer in the world has reported one-hundred percent defect-free CC semi-products manufacturing technology in such a complex and systematic setting [6]. Therefore, complementary technologies such as automatic nondestructive examination (NDE) for CC products surface quality evaluation have become essential in the promotion of HC-DR [7,8]. This is an advisable method to eliminate flaw segments according to accurate NDE evaluation results [9].…”

Continuous casting slab surface crack depth measurement using sinusoidal phase grating method

“…Hot charging and direct rolling of continuous casting slab provides opportunities for energy saving and high productivity; 1 however, to utilise these benefits, precise on-line surface quality evaluation is essential. At present, there are many methods that are used to measure surface defects of continuous casting slab including: charged couple device (CCD) radiation imaging, 2 infra scanner (in hot state), 3,4 laser electromagnetic acoustic transducer testing for subsurface defects 5 and laser scanning imaging method.…”