In the hot rolling process the detection of slab/strip position and width is crucial with respect to optimal positioning and movement of the processed strip between the rolling stands or on the roll out table. In an ideal scenario the slab/strip position and width measurement between each rolling stand allows producing a perfect strip shape and avoids damages caused by strip contacts to the line’s guide rail.
The CMOS camera based EMG hotCAM system is used in hot rolling mills for online position measurement of the strip and for camber measurements. In finishing mills EMG hotCAM especially helps to avoid so called “cobbles” where the strip guidance between the rolling stands fails and the hot material breaks out of the mill, leading to time consuming and costly maintenance operations. In reversing mills the system serves especially for measuring and eliminating the strip camber due to feedback into the rolling process and adjustment of the rolling force.
Keeping the optical path free even in the “Witches' Kitchen”:
The harsh ambient conditions in hot rolling mills prove to be difficult for optical systems. The image quality and the ability to interpolate between individual measuring zones – in case individual images are excessively distorted by steam, oil streaks or dust – depend significantly on the cleanliness of the camera lens. EMG therefore developed an intelligent and secure solution to master this challenge. The new camera housing is flooded with compressed air. The air is guided through a specifically developed "air flow guide block" positioned in front of the camera lens. The “air flow guide block” is produced with modern 3D printing technology allowing the realization of rather complex internal air channels. The result is a predominantly linear air flow, thereby preventing dust, dirt and steam from the environment penetrating into the field of vision of the lens.
The new camera housing has now been applied at an EMG hotCAM installation in a hot mill of a German steel producer for several months. Based on the mill layout this hot mill is known for rather harsh ambient conditions leading to a very intensive contamination of the measurement area with steam and oil emulsion. So far no manual cleaning of the camera viewing window or any other optical camera was required.
Conclusion: EMG hotCAM is an optical measurement system for hot mills. The system can be applied in finishing lines for the position measurement between the rolling stands and for camber measurement after the last rolling stand as well as for camber and position measurement in reversing mills. It is scalable with respect to the number of rolling stands to be equipped. Even amidst adverse ambient conditions (which are especially common in older hot rolling mills) the system is able to operate in a maintenance-free manner for months on end without the need for manual cleaning of the camera lens.
Do you want to know more about EMG hotCAM? If so, you are heartily invited to visit the the ESTAD conference in Düsseldorf which takes place parallel to the METEC trade fair to observe our presentation about “EMG hotCAM: Optical strip position, width and camber measurement in the hot rolling process”. This presentation will be given on June 17th at 16:20.