Mönchengladbach, August 09, 2017

Contactless precision measurement for long products and tubes

Keeping an eye on all parameters for optimal production processes

Ever higher demands on the dimensional precision of rolled material necessitate continuous monitoring of the rolling process. The exact knowledge of the current quality level of the product and rapid reactions to changing process parameters are necessary. Exploitation of tolerances, minimum interruptions in production and low scrap rates guarantee economic success.

Every production line experiences minimal anomalies that are caused by the ingoing material or minute damage to the rolls or roller guides, among other things. All this has an influence on the surface quality and productivity. Producers are facing two challenges: firstly, the defects on the hot surface need to be detected and located; secondly, the cause of the defects needs to be identified and eliminated. Whether it´s tube, rail, bar, wire rod, beam, channel or other section: SMS group teamed up with TBK Automatisierung und Messtechnik GmbH (TBK) to offer the

Measuring systems with laser light section sensors

The measuring system operates on the basis of the “laser light section” technology using four, eight or more sensors performing synchronous, contact-free measurements over the entire crosssection. The sensors developed by TBK measure up to 5,000 contours per second. Therefor special lasers project lines onto the surface of the product. The reflected laser light is captured by cameras and converted into distance values. Using the values recorded by all sensors arranged around the product, the systems can calculate the precise cross-section of the product. The high measurement density means that a high-resolution, 3D model of the product can be created from many 2D cross-sections.

In order to capture complex contours precisely and fully, too, TBK sensors illuminate different contour regions with various laser colors – an essential basis for synchronous measurement. In this way, overlapping areas can also be differentially mapped and precise

Systematic quality improvement based on measurement data

Based on the high-precision crosssection measurements, TBK systems generate precise information that is relevant for rolling process control and upload it back into the production system. Depending on the plant layout, the models are displayed at the plant operators’ workstations and/or are automatically analyzed by SMS group control systems with the aim of improving product quality and efficiency.

True shape size measurement for tube, bar and wire rod

The MEERgauge® laser system for tube, bar and wire rod uses four sensors and has a scanning rate of up to 5,000 scans per second. A true-shape cross-section is created from up to 4,000 synchronous measuring points in a shared coordinate system, and is then displayed with maximum precision. Unlike in conventional systems, the true shape of the contour can be represented precisely. Furthermore the measuring systems allow for closed loop control between the contour measurement and rolling mill control systems. The computer-based interpretation on the measurement results allows roll adjustment corrections to be made while production is ongoing.

Inline measurement of rails and sections

The PROGAUGE section measurement uses the laser-light section method with up to eight sensors. The various quality requirements for the individual section types are accounted for in special sets of key values, meaning the system always calculates precisely the data that is relevant for the desired product quality. With particularly large formats, such as beams with web heights of over one meter, the measurement windows must be correspondingly wide. That is why top priority must be given to the alignment of the sensors in relation to each other. If required, our experts can provide special frame designs to attain the necessary size of the measurement window.

Sensors with high laser capacities of up to 500 mW are included in the technology portfolio and have been applied many times. The measurement window format and the accuracy requirements specified by the plant owner determine how many sensors are used. This means even oversized sections can be reliably measured. Accurate temperature stabilization of the measuring frame is part of the system and ensures high precision measurements independent of ambient temperature variations.

Changeovers from one section type to the next are performed fully automatically, without the operator intervention. This results in significant time and cost benefits during production as well as increased plant availability.

Online surface defect detection with SurfTec

Based on the 3D models created from the high-resolution cross-section measurements, local, atypical anomalies on the surface can be detected. High measuring frequencies provide the required resolution: With up to 5,000 images per second the system shows precise details of even slight anomalies e.g. cracks on the surface.

SurfTec can optionally be integrated in the MEERgauge® or PROGAUGE system and helps plant operators to do both; it determines the precise position of the anomalies on the surface at the time of rolling, evaluates the data using special algorithms and provides the plant owner with information on the cause by classifying the defects. The advantages are twofold: producers can react quickly in the event of surface defects and thus decrease the material scrap. At the same time, they can improve the productive time of the entire plant as they are able to identify the cause of the anomalies far more quickly.

As everybody knows, the steel industry is currently facing problems with overcapacities and this is going along with a deterioration of steel prices. Especially in times like these it is important to optimize the efficiency of existing plants at reasonable investment costs with short payback periods. The above presented measuring systems MEERgauge® and PROGAUGE are only two of a whole bunch of performance modules developed by SMS group in order to make existing mills more efficient.