Olga A. Gasiyarova

The development of ferrous metallurgy, as with most industrial sectors, is progressing toward the adoption of IIoT technologies and the development of digital automatic control systems for electrotechnical and mechatronic complexes. This direction is implemented within the paradigm of digital twins (DTs), which enable the use of advanced design methods, virtual commissioning, and maintenance. The concept of relatively simple object-oriented DTs created using available software and applicable at individual stages of the equipment lifecycle has been substantiated. The relationship between the object-oriented approach and M. Grieves’ classification system has been determined. The contribution of this paper lies in the fact that this problem is addressed for the first time using the example of electrotechnical systems of rolling mills. Definitions of DTs are provided, along with a brief overview of digital platforms developed by leading manufacturers of metallurgical equipment. The development of object-oriented DTs based on Simulink Real-Time modules and domains of the Simscape library is substantiated. A methodology for their virtual tuning using Hardware-in-the-Loop (HIL) simulation is proposed. The results of developing an aggregated DT of interconnected electric drives of the upper and lower rolls (UMD and LMD) of the horizontal stand of the 5000 plate rolling mill are presented. An example of DT implementation in a programmable logic controller (PLC) based on a multicore processor using CODESYS 3.5 software is provided. The advantages and prospects of this approach are discussed. Validation of the results is performed by comparing processes during virtual tuning with oscillograms obtained from the actual mill. Satisfactory accuracy is confirmed, and recommendations for the broader application of the developed object-oriented digital twins are given.

Development of Digital Twins and Digital Control Systems for Electric Drives at Industrial Units predetermines the virtual models creation that must ensure an optimal combination of result accuracy and high-speed data exchange between the control device and the object. Similar tasks arise during the digitalization of rolling mill units, which has been announced in recent years by all leading metallurgical companies. This requires the verification of models for rolling stand electrical complexes, which would ensure the fulfillment of these conflicting requirements. Such a task arose during the electric drive virtual model development of the 5000 heavy-plate rolling mill stand, which is equipped with high-power synchronous motors with variable frequency speed control. Two digital models have been developed, their difference being the degree of the closed-loop stator current control system detail. The first, the more complex model, is built based on Simscape library modules; it provides for the control of current components along the d and q axes. In the second version, the closed current control loop is represented by the first-order lag element. The characteristic feature of the individual electric drives at rolling mill stands is the nonlinearity caused by the saturation (limitation) of the speed controller output and angular backlashes in the spindle connections. These factors must be considered when creating the models and an analysis of their impact on dynamic performance in transient conditions is also necessary. In the presented paper, the verification of the above models for the 5000 mill stand electric drives is carried out. For this purpose, a comparison of the transient processes that occur during the workpiece bite by the rolls with simultaneous closure of the angular backlash was made. The simulation results are compared with the experiments result obtained at the mill and validation of the processes obtained using the studied models was also carried out. Simulations of modes occurring during the rolling cycle have been performed, namely: impact load application with simultaneous angular backlash closure and no-load reversal of the electric drive. They allow for the assessment of the backlash closure influence on the elastic torque amplitude on the spindle. The integrated implementation of simulation and experimental studies ensures the developed model verification, allows for the evaluation of the their advantages and provides recommendations for their application in the digital control systems development.

This article outlines the relevance of building online telemetry systems for online monitoring of the technical conditions of rolling mill equipment. Electromechanical systems of the horizontal stand of the plate Mill 5000 are described, when operating in harsh conditions caused by the shock loading when workpieces enter the stand. It is noted that dynamic torque overloads, exceeding the rated motor torque by many-fold, cause the fatigue failure of spindle joints and breakage of rolls. In this regard, the development and implementation of systems for monitoring the elastic torque on spindles are extremely urgent. This issue has long been studied, but the references provide no information on the building principles and hardware composition of such systems. The use of strain gauges connected according to a balanced bridge circuit to measure the elastic torque is justified. This paper’s contribution is the proposed modular principle for building a telemetry monitoring system based on the analysis of known techniques for measuring and transmitting diagnostic data. The developed system structure is provided and the concept of data transfer and processing are explained. This article suggests the inductive power supply of a measuring unit mounted on a shaft without the use of batteries. A hardware structure was developed to be applied in a system for measuring, transmitting, and visualizing signals proportional to the elastic torque, manufactured on the basis of data measuring instruments by leading companies. The specifics of placement and connection of strain gauges are considered. The hardware providing a wireless power supply to the signal encoder and digital data transfer between the transmitter and receiver is described. The results of implementing the system on Mill 5000 are provided. The installation of a telemetry ring and a receiving head for the inductive power supply and data reception is shown. An experimental assessment of the elastic torques occurring when workpieces enter the cage was obtained by implementing a drive control algorithm which provided biting in the drive acceleration mode. The reliability of measuring the elastic torque with an error not exceeding ±5% and the reduction of dynamic loads on the spindle by 1.3–1.5 times due to the elimination of impacts from closing angular gaps in spindle joints was confirmed. This increases the service life of mechanical equipment and reduces the cost of eliminating the accident aftermath. The prospect of modifying the developed system into a cyber-physical system for monitoring the rolling mill’s mechatronic equipment conditions is shown.

Creating digital twins of industrial equipment requires the development of adequate virtual models, and the calculation of their parameters is a complex scientific and practical problem. To configure and digitally commission automated drives, two-mass electromechanical system models are used. A promising area in which to implement such models is the development of digital shadows, namely drive position observers. Connecting virtual models for online data exchange predetermines the tightening of requirements for their parameter calculation accuracy. Therefore, developing accessible techniques for calculating electromechanical system coordinates is an urgent problem. These parameters are most accurately defined by experiments. The contribution of this paper is the proposition of a method for defining the two-mass system model parameters using the oscillograms obtained in the operating and emergency modes. The method is developed for the horizontal stand drives of a plate mill 5000 and is supported by numerical examples. The technique is universal and comprises calculating the rotating mass inertia torques, elastic stiffness and oscillation damping coefficients, and the time constants of the motor air gap torque control loop. The obtained results have been applied to the development of the elastic torque observer of the rolling stand’s electromechanical system. A satisfactory coordinate recovery accuracy has been approved for both open and closed angular gaps in mechanical joints. Recommendations are given for the use of the method in developing process parameter control algorithms based on automated drive position observers. This contributes to the development of the theory and practice of building digital control systems and the implementation of the Industry 4.0 concept in industrial companies.

The strategic initiative aimed at building “digital metallurgy” implies the introduction of diagnostic monitoring systems to trace the technical condition of critical production units. This problem is relevant for rolling mills, which provide the output and determine the quality of products of metallurgical companies. Making up monitoring systems requires the development of digital shadows and coordinate observers, the direct measurement of which is either impossible or associated with numerous difficulties. These coordinates include the spindle torque applied by the spring-transmitting torque from the motor to the rolling stand rolls. The development and research are conducted by the example of the electromechanical systems of the horizontal stand at the plate mill 5000. The stand electric drive characteristics are given, and the emergency modes that cause mechanical equipment breakdowns are analyzed that. The relevance of analyzing transient torque processes in emergency modes has been accentuated. The paper points to the shortcomings of the system for elastic torque direct measurement, including low durability due to the harsh operating conditions of precision sensors. It also highlights the need to install the measuring equipment after each spindle. The disadvantage of the previously developed observer is the function of calculating the electric drive speed derivative. This causes a decrease in noise immunity and signal recovery accuracy. The contribution of this paper is building a digital elastic torque observer that has advantages over conventional technical solutions, based on the theoretical and experimental studies. The technique for virtual observer adjustment was developed and tested in the Matlab-Simulink software package. For the first time, a comprehensive analysis was conducted for spindle elastic torques in emergency modes that caused equipment damage. An algorithm was developed for an emergency shutdown of a stand electric drive in the worst-case mode of strip retraction between work and backup rolls, due to the overlap of the strip on the roll. Further, the algorithm was tested experimentally. The criteria for diagnosing pre-emergencies was then justified. An adaptive motor-braking rate controller was developed. The developed observer and emergency braking system are in operation at the mill 5000. Long experimental research proved the efficiency of dynamic load monitoring and the reduction in the number of equipment breakdowns.

This paper substantiates why it is necessary to limit the dynamic loads in stand shafts when closing angular gaps. The paper is a feasibility study of a concept developed specifically to limit each of the factors that affect amplitude of the dynamic torque; limitations applied are determined on a case-by-case basis. The research team studied the components of elastic torque in a dual-mass electromechanical system of Mill 5000 caused by vibrations arising from the elasticity of transmission as well as from the vibrations caused by elastic collision itself. It is shown that the lowest possible pre-acceleration is necessary for decreasing the dynamic coefficient at a near-nominal load torque. A principle of limiting dynamic loads when closing an angular gap is proposed, which implies collecting tachograms of an electric drive subjected to positive or negative acceleration before and after the fed metal is captured. The research team has developed drive control principles to implement this approach. The recommendation is to upgrade the electric drives of the reversing stand in Mill 5000.