Quality assurcance in roll production using the SCADA system
Steel rolls of all kinds and sizes are central components of industrial plants. To carry out their duties, plenty of know-how is required during casting and thermal treatment. The quality of the final product must finally be documented by reports.
Over 13 m long, up to 2.5 m in diameter and weighing more than 250 t - these are the data for the largest steel roll manufactured by Gontermann-Peipers. Even the casting of the roll in ingot molds (dies) takes several days, the subsequent post-treatment in the heating furnace up to two months. But it is not every day that a roll of this size is ordered. Many plants and machines require smaller work rolls, back-up rolls or profile rolls, e.g. for cold and hot rolling and forming of steel and aluminum sheets or stainless steel bands. In total, the company processes around 20,000 t of iron per year in its own furnaces - first to steel and then further to steel rolls. Every week, up to 20 rolls of all sizes are cast and thermally and mechanically posttreated. Each of the rolls is manufactured precisely for its area of application according to the specific requirements of the end customer. These requirements include the size, break resistance and hardness of the roll surface, its wear resistance and the uniform behavior of the wear layer over the life of the roll.
Capturing and recording the temperature profiles of the workpieces during heat treatment is of crucial importance to Gontermann-Peipers. It ensures that each roll is heated and cooled according to the specified temperature curve. The data is stored long-term for process security. This requirement for the process control system triggered the need for action: The system previously used no longer met the legal requirements for up-to-date operation and did not contain the functions expected of a modern production plant.
focus used the Simatic WinCC V7 Scada system from Siemens as the process control system. Due to its scalability, it is suitable for any plant size and configuration. The respective quantity structures can be adapted, redundant servers or remote access options via the Internet can be implemented. Future modernizations and expansions can be flexibly implemented, further modules can be added and data collection points can be integrated.
The controller passes on its data to the control system. All production-relevant data of the rolls, such as the temperature characteristics, are provided by the higher-level ERP system. For this purpose, WinCC accesses the same Oracle database used by the higher-level ERP system via script. The consistency of the data from both systems avoids errors in the thermal treatment of the rolls and duplicate entries.
In the process control system, the characteristic data of the rolls are compared with the ERP system before the thermal treatment in the furnace starts. The return of the seamlessly recorded temperature data to the ERP system during the heating and cooling phases after the thermal treatment serves as proof of product quality.
A total of about 300 measured values are recorded and stored by the control system in a one-minute cycle. These data are transferred to the ERP system for further processing and storage. Manual corrections can be made at any time, either at the control station in the kiln hall or at one of the operator stations in production. Trends, characteristic curves and reports can be parameterized and exported without scripts, for example to Microsoft Excel.