Multi-beam fibre-optic laser scanning system for surface defect recognition

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.

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“…Figure 1 shows a possible flow diagram in which every billet experiences either cold charged rolling (CCR), DCR or HCR 7…”

Section: Hot Billet Surface Defect Inspectionmentioning

confidence: 99%

“…5,6 Hot billet surface defect inspection Alternative components for detecting system Figure 1 shows a possible flow diagram in which every billet experiences either cold charged rolling (CCR), DCR or HCR. 7 As shown in Fig. 1, a CC billet surface is supposed to undergo an online inspection just after the billet is cast.…”

Section: Introductionmentioning

confidence: 99%

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

Ouyang

Zhang

Zhao

et al. 2011

Ironmaking & Steelmaking

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“…The main advantages of laser inspection methods are their ability to scan large areas, their applicability to in-process measurement and their ability to resist noise interference caused by high temperature, oxide skin and oscillation marks on the surface of the continuous casting slab. 3 The main driver for research in this area today has been to produce laser CCD displacement techniques, which can be used for a variety of inspection sensors. This research holds the potential to provide an effective measurement technology, which can compete with conventional image inspection methods.…”

Section: Introductionmentioning

confidence: 99%

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

Ouyang

Zhao

et al. 2011

Ironmaking & Steelmaking

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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.

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“…The automatic and low cost inspection instrument is urgently required. With the virtues of low price, high-speed, non-destructive [4] optical fiber sensing technology is applied to inspection of steel ball surface defects in this paper.…”

Section: Introductionmentioning

confidence: 99%

Defects Inspection of Steel Ball Based on Optical Fiber Sensing Technique

Zhang

et al. 2011

AMM

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Surface quality of bearing ball is one of important factors to improve service performance. It is difficult to detect bearing ball surface defects with high precision and low cost by conventional methods. In this paper one new classification method based on optical fiber sensing technology was put forward from the longitudinal section angle. Inspection mechanism of Y-type and coaxial fiber sensor were analyzed, the mathematical models of the two fiber sensors were established and numerical simulations were realized by Matlab software. Influence of optical fiber parameters on light intensity modulation characteristic regulation was studied. Light intensity modulation characteristic experiments were done with specimens of different reflectivity and processing methods. The results show optical fiber sensing technique is an effective method to separate different surface of steel ball with extracting of two parameters displacement and surface reflectivity.

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Multi-beam fibre-optic laser scanning system for surface defect recognition

Cited by 11 publications

References 12 publications

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

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

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

Defects Inspection of Steel Ball Based on Optical Fiber Sensing Technique

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