Camera Vision Technology – Miss Crop Detection System and Hot Strip Bar Uptrend Detection System

1) Where is the technology being used? ; All five (5) Hot Strip Rolling Mills of POSCO(Old name: Pohang Iron and Steel Co., Ltd.), Republic of Korea)

2) When the technology has been implemented? ; June, 2001 ~ October, 2006

3) Background of the Development

Normally at each hot rolling mill, there is a cutting machine right in front of finishing rolling process, which is called ‘Crop Shear’, and by which both head and tail parts of a hot strip bar are cut. At this moment, if the cut parts, so called ‘crop’, put into the finishing rolls, as they not taken off from the bar, the later are severely damaged and the milling has to be stopped immediately and the resulting loss, such as production stop and inevitable maintenance cost is of a quite cruel nature. Secondly the milling line needs an intelligent system to guarantee optimized cross-cutting lines for both economical and quality assurance respects. Before the technology has been developed, line operators had been using two I-TV cameras, one installed over crop dropping chute and the other over the crop shear, to check the cutting status and dropping but they couldn’t judge the status exactly without any error, due to the fast crop falling speed (Approximately 6m/sec) and harsh environment condition around the cutting and dropping station. JangWon SM Co., Ltd. provided POSCO with a customized solution, where the state-art-of camera vision technology were utilized to realize the key algorithms for the recognition of taking off of crops and optimized cross-cutting for the both head/tail crops.

4) Technical difficulty for the development
The followings were technically difficult matters in realizing the algorithms.

• High crop dropping speed: Max. 6m/sec
• There always are heavy water vapor and oily and dusty fume around the crop shear and also dropping chute, especially too heavy water vapor and fume during the winter season. They hinter the cameras from acquiring images of head/tail parts of bars and also those of the crops.
• Even during other seasons, the oily and dusty materials get on the cover glass in front of camera lens, disabling cameras to see the objects.

5) Target of system development
The system has been installed between crop shearing machine and the first finishing rolling station, playing the following roles.

• Acquisition of images for crops of head/tail parts of hot bars.
• Acquisition of images for shapes of head/tail parts after the crops cut
• Notifying operators of failure of separation of crops from the bars, providing them with warning information, and so fatal accidents in costly rolling facility resulting from cutting mistakes to be avoided
• Adequateness of cutting position in longitudinal direction

6) Improvement after the system installed

The suppression of facility accident leads POSCO to enhanced productivity and the computation of exact cutting length prevent POSCO from over-cutting and under-cutting, i.e., the length data cane be used for setting up of the most reasonable and economic cutting line.

7) Further developed products

This camera vision technology has been applied for Hot Strip Bar Uptrend Detection System for POSCO. At the roughing mills in hot rolling strip mills of POSCO, they had been so often encountered large accidents of collision between moving strips bended upward and roller tables. Once JangWon SM Co., Ltd. Installed the ‘Hot Strip Bar Uptrend Detection System’, POSCO has saved spiritual stress imposed on operator, maintenance cost and consequently the system has enhanced their productivity.

* POSCO granted JangWon SM Co. Ltd. the right of execution of Patent for above two(2) technologies.