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Process control in steel core production to reduce of power losses in electrical machines and transformers: Process Control
Mälardalen University, Department of Public Technology. (Process control and simulation)
Mälardalen University, Department of Public Technology.
Mälardalen University, Department of Public Technology.ORCID iD: 0000-0002-7233-6916
2009 (English)In: Proceedings MATHMOD 09 Vienna, Vienna- Austria: Mathematical Modelling (MATHMOD) 2009 , 2009Conference paper, Published paper (Refereed)
Abstract [en]

The main aim of cold rolling is reduction of strips to the desired final thickness. As the cold rolled strip is being manufactured from hot rolled strip, the uniformity of width, thickness, hardness, etc. are all now intended for improvement.  To reach to this target, need to abound control system to reach the higher quality of slabs.  It should satisfy the several factors, as regards geometrical, mechanical, chemical and surface properties.

Process control has taken advantage of new measurement equipments, new control actuators and algorithms. Automation and automatic process control can advance the quality further than what is achievable by manual control. This is an important desideration in rolling industry that rolling of slabs needs advanced and optimized process control to increase the productivity and reduction of the variations in the final properties.

A typical cold rolling stand performs one step in a chain of processes in the cold rolling mill, which can include pickling, rolling, annealing, temper rolling and downstream processes. All these processes contribute to the final properties of the strips. When the main process or the main objective is well controlled, it is important to continue with the other processes. In continuous annealing furnaces, the temperature controls the mechanical properties, but temperature differences and bending around rollers change the flatness. Temper rolling needs the same flatness control as other cold rolling processes. Cooling and lubrication can affect several properties of the strips.

Precise general control of the strip in a cold steel rolling mill will be discussed in this article.

Typically, the rolling process is modelled with numerical techniques. But these are not appropriate for a controller design, because they are too difficult. Thus, a linear mathematical model for the rolling process is presented here, which describes the interaction of the required influencing parameters. The attempt leads to numerically professional algorithms, which are essential to run in a real-time situation. With the help of these linear descriptions, the vital elements for the control are investigated. Modern rolling mills are equipped with a servo-hydraulic gap adjustment system, eccentricity control of the rolls, thickness, speed, force and tension controls.

A model to optimize of the control design process and increasing of accuracy is presented. In this way using the process transfer function in system at different control mode like to thickness, flatness, shape and etc designed a PID and PI optimized controller with using of the best optimization method, final properties increased. The measurements are used to verify the model approach and to detect the most significant sources of disturbances.

A new linearised numerical model for the rolling process which is suitable for closed loop control has been developed. The model is based on the calculation of the operating point using an available numerical method, followed by determining the partial derivatives at the operating point with respect to all input parameters. Finally, the partial derivatives are combined using superposition to describe the behaviour of the complete system. In this manner, the changes in the output parameters can be determined for small changes in the input parameters. This calculation is numerically efficient and suitable for use in closed loop control.

Moreover, the roll eccentricity problem and the possibilities to perform compensation will be explained here. Due to the great variety of solutions, a classification of the methods will be sketched. The basic properties of these classes are discussed. Then, a special solution is presented, which has proved its worth already in a practical application. The investigation of its properties is proposed to be typical for the every class, to which the method belongs.

Finally measurement data which can be used to verify the new model will be performed. The model has been incorporated as a simulation system developed by the authors who enable the simulation of a multi-pass single stand rolling process. To get practical information about the rolling process, a data logging system was developed and installed in Sura AB for data collection.

Place, publisher, year, edition, pages
Vienna- Austria: Mathematical Modelling (MATHMOD) 2009 , 2009.
Keywords [en]
Control-modelling-kalman-optimization-cold rolling
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Energy- and Environmental Engineering
Identifiers
URN: urn:nbn:se:mdh:diva-6838ISBN: 978-3-901608-35-3 (print)OAI: oai:DiVA.org:mdh-6838DiVA, id: diva2:236009
Conference
MATHMOD 2009 (6th Vienna International Conference on Mathematical Modelling), Feb. 11, 2009, Vienna, Austria
Available from: 2009-09-19 Created: 2009-09-19 Last updated: 2015-07-31Bibliographically approved

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Dahlquist, Erik

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Mousavi Takami, KouroshMahmoudi, JafarDahlquist, Erik
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