Project Source

This project originated from the industry-university-research cooperation between Shougang Guiyang Special Steel Co., Ltd. (Guigang) and the University of Electronic Science and Technology of China, aiming to tackle the long-standing quality monitoring challenges in the steel industry. When producing its main products (such as hexagonal steel billets and round steel), Guigang faces product disqualification issues caused by surface defects and out-of-tolerance contour dimensions, resulting in huge economic losses every year. To improve product quality and reduce losses, the two parties jointly developed this online real-time monitoring system that integrates contour measurement and surface defect detection.

Project Background and Requirements

1.Industry Pain Points and Necessity

During the rolling process of high-temperature bars, two major core quality issues are surface defects such as cracks and out-of-tolerance in diameter or opposite side dimensions. If these unqualified products cannot be detected and rejected in real-time on the production line, a large number of defective products will flow into the market, bringing huge economic losses and brand reputation risks to enterprises. The annual losses faced by Guigang (Guizhou Steel) due to this are as high as millions of yuan, which is also a common problem generally existing in major steel mills at home and abroad.

2.Current status and gaps in technology both domestically and internationally

At the time of project initiation, there were three companies in the international market offering related equipment, but all of them had functional limitations:

• Danieli (Italy): Profilometer, only measures contours, does not inspect surface defects, and has slightly lower accuracy.
• American Youjie: The "Hot Eye" system only inspects surface defects and does not measure contours.
• Siemens (Germany): Diameter gauge, high precision but slow speed, and also does not monitor defects.

Project Features and Technical Solutions

The core feature of this system lies in integrating contour measurement and surface crack identification functions, and successfully solving the problem of stable operation in harsh industrial environments with high temperatures, high dust levels, and strong vibrations.

Main Technical Solutions and Innovation Points

1.360° contour measurement solution

Multi-camera line structured light technology is adopted. Multiple lasers and image sensors project and collect light from different angles, and then through technologies such as image fusion and distortion correction, the complete 360° contour of the steel billet is finally synthesized, and the diameter of round steel or the size of opposite sides of hexagonal steel is accurately calculated.

2.Surface crack identification scheme

An advanced image recognition algorithm has been developed, which can effectively eliminate non-defect interferences such as surface iron filings, floating dust, dripping water droplets, and characters on steel billets, accurately identify real surface cracks, and greatly reduce the misjudgment rate.

3.Laser Locking Imaging Technology

This is one of the core innovations of this project. Through specific phase detection and digital image processing technologies, it is possible to extract weak laser signals from the strong background light emitted by the steel billet itself, thereby "locking" a clear contour light band and completely eliminating the impact of the light emitted by the high-temperature steel billet on measurement accuracy.

4.Measures to Cope with Harsh Environments

• High temperature: All cables use high-temperature cables resistant to 200℃, and both the laser and the camera are equipped with closed water-cooling jackets.
• High dust: Install glass shielding windows and dust-proof hoods in front of optical components.
• Strong vibration: The laser and camera are designed with an integrated rigid structure to avoid relative displacement.

Project Role and Effectiveness

• Quality improvement: Achieved 100% online real-time inspection of billets on the production line, promptly removed unqualified products, and significantly enhanced the quality consistency of ex-factory products.
• Cost reduction: It avoids batch quality losses and directly helps enterprises recover economic losses at the million-yuan level every year.
• Technological breakthrough: Successfully broke the foreign technological monopoly, created the first domestic system that simultaneously has the capabilities of contour and surface defect detection and is adaptable to extreme working conditions, and improved the level of intelligent manufacturing in the domestic steel industry.
• Stable and reliable: After multiple on-site debugging and optimization, the system can finally operate stably for a long time in harsh environments with high temperatures, high dust, and strong vibrations, meeting the needs of continuous production in industrial sites.

Related videos

Video and PDF download

Online Monitoring System for Contour Dimensions and Surface Defects of High-Temperature Bars Using Laser Lock-in Imaging.pdf