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For the production of various machine-building products - rolling rolls, parts of power equipment, piercing mandrels - complex alloy steels containing chromium and a significant number of other deficient alloying elements (nickel, vanadium, molybdenum) type 38Ni3CrMoV are used. The paper presents the results of research on the influence of modes of hardening and subsequent cryogenic treatment on the parameters of the structure, hardness and wear resistance of this steel. Visible changes in the microstructure of thermally improved steel samples during cryogenic treatment were not found, which can be explained by the high thermodynamic stability of the sorbitol structure and the practical absence of residual austenite due to its decomposition during high tempering. It is shown that cryogenic treatment of thermally improved 38Ni3CrMoV steel contributes to an increase in the hardness, toughness and wear resistance this steel (~3.8 %). In this case, there is a slight increase in the parameter and magnitude of microstresses of the crystal lattice, an increase in the density of dislocations due to the removal of thermal stresses. To obtain a multiphase structure of 38Ni3CrMoV steel with retained austenite, isothermal quenching from the γ - α region has been proposed. The use of cryogenic treatment for the experimental mode of hardening of 38Ni3CrMoV steel samples promotes the transformation of retained austenite in the final structure of the samples into martensite with a significant increase in the microhardness of its structural components at the 22.3 %. The experimental hardening mode + cryogenic treatment provides a significant increase in the hardness and wear resistance of 38Ni3CrMoV steel at the 21.6 % while ensuring a certain level of its impact toughness (more than 4 J/cm2) and can be recommended for the implementation of the technology of differentiated hardening of large-sized products made of 38Ni3CrMoV steel. Keywords: steel, structure, hardness, wear resistance, isothermal hardening, cryogenic treatment.
S.V. Bobyr; P.V. Krot; G.V. Levchenko; O.Ye. Baranovska; D.V. Loshkarev. Influence of modes of thermal hardening and the subsequent cryogenic processing on structure and properties of steel 38Ni3CrMoV. Metaloznavstvo ta obrobka metalìv 2021, 98, 14 -22.
AMA StyleS.V. Bobyr, P.V. Krot, G.V. Levchenko, O.Ye. Baranovska, D.V. Loshkarev. Influence of modes of thermal hardening and the subsequent cryogenic processing on structure and properties of steel 38Ni3CrMoV. Metaloznavstvo ta obrobka metalìv. 2021; 98 (2):14-22.
Chicago/Turabian StyleS.V. Bobyr; P.V. Krot; G.V. Levchenko; O.Ye. Baranovska; D.V. Loshkarev. 2021. "Influence of modes of thermal hardening and the subsequent cryogenic processing on structure and properties of steel 38Ni3CrMoV." Metaloznavstvo ta obrobka metalìv 98, no. 2: 14-22.
The low energy efficiency and excessive power of electric motors of large-scale vibrating machines for processing bulk materials motivated a new design of the inertial drive. This drive consists of one motor and two coaxial unbalanced masses, whose rotational frequencies are related in the ratio 2:1. This approach allows for a generation of the excitation force with variable amplitude and frequency, which changes depending on the inertial characteristics and shaft rotation frequency and does not relate to the phase difference of the unbalanced masses. Because of this, the symmetry axis of the resulting vector hodograph can be changed. The spectral composition of the exciting force up to 200 Hz contains higher harmonics, the energy share of which is 25.4% from the 2nd harmonic and 14.1% from the 3rd and higher harmonics that correspondingly improves bulk material treatment in comparison to single-frequency vibrators. The finite element model is used for checking the strength capacity of the most loaded units of a dual-frequency drive. Its use allows the realization of complex trajectories of motion that are more technologically efficient for variable parameters of the treated media and energy saving in sieving screens and other vibrating machines.
Volodymyr Gursky; Igor Kuzio; Pavlo Krot; Radoslaw Zimroz. Energy-Saving Inertial Drive for Dual-Frequency Excitation of Vibrating Machines. Energies 2020, 14, 71 .
AMA StyleVolodymyr Gursky, Igor Kuzio, Pavlo Krot, Radoslaw Zimroz. Energy-Saving Inertial Drive for Dual-Frequency Excitation of Vibrating Machines. Energies. 2020; 14 (1):71.
Chicago/Turabian StyleVolodymyr Gursky; Igor Kuzio; Pavlo Krot; Radoslaw Zimroz. 2020. "Energy-Saving Inertial Drive for Dual-Frequency Excitation of Vibrating Machines." Energies 14, no. 1: 71.
Tumbling mills have been widely implemented in many industrial sectors for the grinding of bulk materials. They have been used for decades in the production of fines and in the final stages of ore comminution, where optimal levels for the enrichment particles’ sizes are obtained. Even though these ubiquitous machines of relatively simple construction have been subjected to extensive studies, the industry still struggles with very low energy efficiency of the comminution process. Moreover, obtaining an optimal size for the grinding product particles is crucial for the effectiveness of the following processes and waste production reduction. New, innovative processing methods and machines are being developed to tackle the problem; however, tumbling mills are still most commonly used in all ranges of the industry. Since heavy equipment retrofitting is the most costly approach, process optimization with dedicated models and control systems is the most preferable solution for energy consumption reduction. While the classic technological measurements in mineral processing are well adopted by the industry, nowadays research focuses on new methods of the mill’s internal dynamics analysis and control. This paper presents a retrospective overview of the existing models of internal load motion, an overview of the innovations in process control, and some recent research and industrial approaches from the energy consumption reduction point of view.
Mateusz Góralczyk; Pavlo Krot; Radosław Zimroz; Szymon Ogonowski. Increasing Energy Efficiency and Productivity of the Comminution Process in Tumbling Mills by Indirect Measurements of Internal Dynamics—An Overview. Energies 2020, 13, 6735 .
AMA StyleMateusz Góralczyk, Pavlo Krot, Radosław Zimroz, Szymon Ogonowski. Increasing Energy Efficiency and Productivity of the Comminution Process in Tumbling Mills by Indirect Measurements of Internal Dynamics—An Overview. Energies. 2020; 13 (24):6735.
Chicago/Turabian StyleMateusz Góralczyk; Pavlo Krot; Radosław Zimroz; Szymon Ogonowski. 2020. "Increasing Energy Efficiency and Productivity of the Comminution Process in Tumbling Mills by Indirect Measurements of Internal Dynamics—An Overview." Energies 13, no. 24: 6735.
The monitoring of drilling processes is a well-known topic in the mining industry. It is widely used for rock mass characterization, bit wear monitoring and drilling process assessment. However on-board monitoring systems used for this purpose are installed only on a limited number of machines, and breakdowns are possible. There is a need for a data acquisition system that can be used on different drilling rigs and for an automatic data analysis procedure. In this paper, we focused on the automatic detection of drilling cycles, presenting a simple yet reliable system to be universally installed on drilling rigs. The proposed solution covers hardware and software. It is based on the measurement of electric current and acoustic signals. The signal processing methods include threshold-based segmentation, a short-time envelope spectrum and a spectrum for the representation of results. The results of the research have been verified on a real drilling rig within the testing site of its manufacturer by comparing the results with the data of the on-board monitoring system installed on the machine. Novel aspects of our approach include the detection of the pre-boring stage, which has an intermediate amplitude that masks the real drilling cycles, and the use of the percussion instantaneous frequency, which is estimated by acoustic recordings.
Jacek Wodecki; Mateusz Góralczyk; Pavlo Krot; Bartłomiej Ziętek; Jaroslaw Szrek; Magdalena Worsa-Kozak; Radoslaw Zimroz; Paweł Śliwiński; Andrzej Czajkowski. Process Monitoring in Heavy Duty Drilling Rigs—Data Acquisition System and Cycle Identification Algorithms. Energies 2020, 13, 6748 .
AMA StyleJacek Wodecki, Mateusz Góralczyk, Pavlo Krot, Bartłomiej Ziętek, Jaroslaw Szrek, Magdalena Worsa-Kozak, Radoslaw Zimroz, Paweł Śliwiński, Andrzej Czajkowski. Process Monitoring in Heavy Duty Drilling Rigs—Data Acquisition System and Cycle Identification Algorithms. Energies. 2020; 13 (24):6748.
Chicago/Turabian StyleJacek Wodecki; Mateusz Góralczyk; Pavlo Krot; Bartłomiej Ziętek; Jaroslaw Szrek; Magdalena Worsa-Kozak; Radoslaw Zimroz; Paweł Śliwiński; Andrzej Czajkowski. 2020. "Process Monitoring in Heavy Duty Drilling Rigs—Data Acquisition System and Cycle Identification Algorithms." Energies 13, no. 24: 6748.
The problem solved in this research is the diagnosis of the radial clearances in bearing supports and the loosening of fastening bolts due to their plastic elongation (creep) or weak tightening using vibration signals. This is an important issue for the maintenance of the heavy-duty gearboxes of powerful mining machines and rolling mills working in non-stationary regimes. Based on a comprehensive overview of bolted joint diagnostic methods, a solution to this problem based on a developed nonlinear dynamical model of bearing supports is proposed. Diagnostic rules are developed by comparing the changes of natural frequency and its harmonics, the amplitudes and phases of shaft transient oscillations. Then, the vibration signals are measured on real gearboxes while the torque is increasing in the transmission during several series of industrial trials under changing bearings and bolts conditions. In parallel, dynamical torque is measured and its interrelation with vibration is determined. It is concluded that the radial clearances are the most influencing factors among the failure parameters in heavy-duty gearboxes of industrial machines working under impulsive and step-like loading. The developed diagnostics algorithm allows condition monitoring of bearings and fastening bolts, allowing one to undertake timely maintenance actions to prevent failures.
Pavlo Krot; Volodymyr Korennoi; Radoslaw Zimroz. Vibration-Based Diagnostics of Radial Clearances and Bolts Loosening in the Bearing Supports of the Heavy-Duty Gearboxes. Sensors 2020, 20, 7284 .
AMA StylePavlo Krot, Volodymyr Korennoi, Radoslaw Zimroz. Vibration-Based Diagnostics of Radial Clearances and Bolts Loosening in the Bearing Supports of the Heavy-Duty Gearboxes. Sensors. 2020; 20 (24):7284.
Chicago/Turabian StylePavlo Krot; Volodymyr Korennoi; Radoslaw Zimroz. 2020. "Vibration-Based Diagnostics of Radial Clearances and Bolts Loosening in the Bearing Supports of the Heavy-Duty Gearboxes." Sensors 20, no. 24: 7284.
Operation of industrial metallurgical plants is associated with significant wear in spindles, gearboxes and bearings where difficult to implement digital diagnostic tools due to harsh operating conditions. Angular and radial gaps produce extremely high dynamic loads and abrupt failures in the multi-stand hot rolling mills. Reliable vibration monitoring is very complicated due to inherent changes of technological regimes, treated material and drive speed. It appears more beneficial to monitor dynamic torques in addition to vibration signals, but this is restricted to the installation of strain gauges. The more acceptable approach is to monitor static torques of electric motors and, having identified multi-body models, to calculate remaining useful life (RUL) of elements. Based on this approach, the new monitoring system is developed for the multi-stand mill with integration into plant automation infrastructure. Parameters adaptation of nonlinear dynamical models is provided and technological loads optimization by the criterion of RUL in rolling stands. System supports a database of maintenance actions and elements failures. Reports are generated on overloading and RUL.
Pavlo Krot; Ihor Prykhodko; Valentin Raznosilin; Radoslaw Zimroz. Model Based Monitoring of Dynamic Loads and Remaining Useful Life Prediction in Rolling Mills and Heavy Machinery. Blockchain Technology and Innovations in Business Processes 2020, 399 -416.
AMA StylePavlo Krot, Ihor Prykhodko, Valentin Raznosilin, Radoslaw Zimroz. Model Based Monitoring of Dynamic Loads and Remaining Useful Life Prediction in Rolling Mills and Heavy Machinery. Blockchain Technology and Innovations in Business Processes. 2020; ():399-416.
Chicago/Turabian StylePavlo Krot; Ihor Prykhodko; Valentin Raznosilin; Radoslaw Zimroz. 2020. "Model Based Monitoring of Dynamic Loads and Remaining Useful Life Prediction in Rolling Mills and Heavy Machinery." Blockchain Technology and Innovations in Business Processes , no. : 399-416.
This research paper represents the results of abrupt failure investigation in the structure of industrial plant for hydrostatic pressure testing of tubes. The significant damages of testing machine elements are observed after the moving tube impact when the opposite tube end cap has been suddenly released because of the screw-thread defect. The water pressure inside the tube at the time of the incident was only 20 MPa while the maximal pressure of 125 MPa is required by tubes tests specification. Therefore, based on admitted assumptions, the detailed analysis is conducted of static and dynamic forces acting on elements of structure to avoid full machine destruction in case of the next incidents under higher pressures. Conditions are determined of the sharp cap end penetration into thrust plate and possible damage of upper protection casing from the water jet and tube pieces impacts under conditions of the crack opening in the tested tube. The two options are proposed of plant modernization to reinforce structure for safety work under pressure from 70 MPa to 125 MPa depending on tube size and testing conditions. The developed improvements of machine structure allow simultaneously increasing the productivity of testing plant up to 14–20 tubes per hour depending on their sizes.
Pavlo V. Krot; Radoslaw Zimroz. Failure analysis and modernization of high-pressure hydraulic press for drilling tubes testing. Engineering Failure Analysis 2020, 117, 104772 .
AMA StylePavlo V. Krot, Radoslaw Zimroz. Failure analysis and modernization of high-pressure hydraulic press for drilling tubes testing. Engineering Failure Analysis. 2020; 117 ():104772.
Chicago/Turabian StylePavlo V. Krot; Radoslaw Zimroz. 2020. "Failure analysis and modernization of high-pressure hydraulic press for drilling tubes testing." Engineering Failure Analysis 117, no. : 104772.
The minerals processing enterprises are widely using vibrating machines to separate different fractions of materials. Sieving efficiency is greatly dependent on particle trajectories, or orbit, of periodical motion over the sieving decks. A screening process is very dependable on design parameters such as the vibrator power, synchronisation of their drives, and oscillation frequency as well as the stiffness of supporting springs. Deterioration of supporting springs (stiffness reduction and cracks) due to cyclic loading and fatigue is difficult to determine by the visual inspection, static loading tests, or nondestructive testing techniques. Vibration monitoring systems of different vendors are analysed where vibration sensors usually installed on the bearings of vibrators are as well used for supporting springs diagnostics. However, strong cyclic components from the unbalanced exciters and stochastic disturbances from the input stream and vibrating pieces of the material make analysis a not trivial task. The considered vibrating screen is investigated on the 6-DOF (degree-of-freedom) dynamical model to reflect all linear and rotational components of spatial motion. Besides the main periodic motion, the model accounts for stochastic alpha-stable distributed impacts from the material. Instead, the Gaussian normal distribution is considered for the position of equivalent force application point. Supporting springs are represented by the bilinear stiffness characteristics. Specific features of vibration signals (angle of orbit inclination, natural frequency change, harmonics of natural frequency, and phase space plots) are analysed to recognise the weak nonlinear features of a system under conditions of small stiffness changes in springs. The extensive measurements are conducted on the industrial vibrating screen, and the dynamic model is verified by the measurement data. Recommendations are given on failure diagnostics of springs in the industrial vibrating screens.
Pavlo Krot; Radoslaw Zimroz; Anna Michalak; Jacek Wodecki; Szymon Ogonowski; Michal Drozda; Marek Jach. Development and Verification of the Diagnostic Model of the Sieving Screen. Shock and Vibration 2020, 2020, 1 -14.
AMA StylePavlo Krot, Radoslaw Zimroz, Anna Michalak, Jacek Wodecki, Szymon Ogonowski, Michal Drozda, Marek Jach. Development and Verification of the Diagnostic Model of the Sieving Screen. Shock and Vibration. 2020; 2020 ():1-14.
Chicago/Turabian StylePavlo Krot; Radoslaw Zimroz; Anna Michalak; Jacek Wodecki; Szymon Ogonowski; Michal Drozda; Marek Jach. 2020. "Development and Verification of the Diagnostic Model of the Sieving Screen." Shock and Vibration 2020, no. : 1-14.
The amount of residual austenite in martensitic roll steels is an important technological parameter of heat treatment, which affects the performance properties of the rolls. But determining its amount in roll steels is a complex and not fully solved scientific and technical problem. The aim of the work was to comparatively analyze the amount of residual austenite in the structure of alloy steel rolls by X-ray diffraction, ultrasonic methods and metallography analysis. However, the qualitative difference of microstructures in the content of the light phase - austenite, confirms the results of X-ray diffraction analysis. No correlation was found between the austenite content in the samples and their hardness. It was found that the X-ray method, based on the comparison of the intensities of the α- and γ-phase lines of iron, overestimates the value of the amount of residual austenite in some samples of roll steels. The results of the analysis of residual austenite by ultrasound rate showed better convergence. The amounts of residual austenite, calculated on the sample of stainless steel (100% γ-Fe), had reduced values (2.6-4.5%). The most accurate results on the amount of residual austenite gave the use of the established regression dependence with the selected standard (2.7-7.8%). This dependence is obtained at the speed of sound in austenite ~ 4000 m / s. It is determined that the application of the ultrasonic method allows to determine the content of residual austenite in the samples of roll steels quite quickly and accurately.
S.V. Bobir; I.Yu. Prikhodko; D.V. Loshkarev; S.S. Zakharchuk; P.V. Krot. Analysis of the amount of retained austenite in the structure of steel rolls for sheet rolling. Fundamental and applied problems of ferrous metallurgy 2020, 1 .
AMA StyleS.V. Bobir, I.Yu. Prikhodko, D.V. Loshkarev, S.S. Zakharchuk, P.V. Krot. Analysis of the amount of retained austenite in the structure of steel rolls for sheet rolling. Fundamental and applied problems of ferrous metallurgy. 2020; (34):1.
Chicago/Turabian StyleS.V. Bobir; I.Yu. Prikhodko; D.V. Loshkarev; S.S. Zakharchuk; P.V. Krot. 2020. "Analysis of the amount of retained austenite in the structure of steel rolls for sheet rolling." Fundamental and applied problems of ferrous metallurgy , no. 34: 1.
Kostiantyn Baiul; Aleksander Khudyakov; Sergii Vashchenko; Pavlo V. Krot; Nataliia Solodka. The experimental study of compaction parameters and elastic after-effect of fine fraction raw materials. Mining Scince 2020, 27, 7 -18.
AMA StyleKostiantyn Baiul, Aleksander Khudyakov, Sergii Vashchenko, Pavlo V. Krot, Nataliia Solodka. The experimental study of compaction parameters and elastic after-effect of fine fraction raw materials. Mining Scince. 2020; 27 ():7-18.
Chicago/Turabian StyleKostiantyn Baiul; Aleksander Khudyakov; Sergii Vashchenko; Pavlo V. Krot; Nataliia Solodka. 2020. "The experimental study of compaction parameters and elastic after-effect of fine fraction raw materials." Mining Scince 27, no. : 7-18.
A real case study is represented of abrupt failures in a new multi-motor gear drive of vertical rolls in the heavy slabbing mill. Modal analysis is conducted, and the lowest torsional vibration modes are verified by the data from an industrial plant. Conditions of parametric resonances due to variable stiffness of teeth are determined within the range of working speed. The branched gear drive is investigated by the non-linear dynamical model with backlashes. It is shown that instantaneous dynamic loads in driveline are strongly dependent on the difference in gap sizes and phase shift between two intermediate gears in the output gear wheel coupling. Deviation in electrical parameters by 0.5 % is considered as the additional cause of not equal load sharing of parallel motors. Results of this research allowed preventing further failures of the gearbox and optimizing slabbing mill control. The proposed approach can be used in other multi-motor machines.
Pavlo V. Krot. Dynamical processes in a multi-motor gear drive of heavy slabbing mill. Journal of Vibroengineering 2019, 21, 2064 -2081.
AMA StylePavlo V. Krot. Dynamical processes in a multi-motor gear drive of heavy slabbing mill. Journal of Vibroengineering. 2019; 21 (8):2064-2081.
Chicago/Turabian StylePavlo V. Krot. 2019. "Dynamical processes in a multi-motor gear drive of heavy slabbing mill." Journal of Vibroengineering 21, no. 8: 2064-2081.
Large-scale vibrating screens are widely used in minerals processing industry. One of main components in any vibrating screen is a set of springs supporting the main body of machine with sieving material inside. These springs are subjected to cyclic loading and fatigue. Changing of their stiffness and subsequent failures have influence on the sieving efficiency and are difficult to predict, hence, online condition monitoring is required. Visual inspection and non-destructive diagnostic methods are not sufficient in this case. Noisy signals from vibration sensors installed on bearings supports of rotating unbalanced exciters are preferably used for diagnostics of spring failures. In this research, vibrating screen motion is represented by multi-DOF (degree-of-freedom) dynamic model, which accounts stochastic disturbances from incoming material and impacts on sieving decks. Specific features of vibration signals are analysed to identify springs deterioration modelled as the bilinear stiffness characteristics. Phase space plots (PSP) are considered as the promising method to recognise nonlinear behaviour of system under the presence of spring damage. Advantages are assessed of spring stiffness change and failures diagnostics as compared with other methods.
Pavlo Krot; Radoslaw Zimroz. Methods of Springs Failures Diagnostics in Ore Processing Vibrating Screens. IOP Conference Series: Earth and Environmental Science 2019, 362, 012147 .
AMA StylePavlo Krot, Radoslaw Zimroz. Methods of Springs Failures Diagnostics in Ore Processing Vibrating Screens. IOP Conference Series: Earth and Environmental Science. 2019; 362 (1):012147.
Chicago/Turabian StylePavlo Krot; Radoslaw Zimroz. 2019. "Methods of Springs Failures Diagnostics in Ore Processing Vibrating Screens." IOP Conference Series: Earth and Environmental Science 362, no. 1: 012147.
The identification for the operational cycles of underground haul trucks is considered in the paper. In previous works related to LHD (Load Haul Dump) vehicles and haul trucks, a hydraulic pressure signal was used. In this paper, it is shown how to determine operational cycles when the pressure sensor in the unloading mechanism is either not available or damaged. The virtual sensor for the identification of operational cycles is based on logical conditions that include standard signals from the electronic control units (ECU) of underground haul trucks. These signals are braking pressure, gear selection, vehicle speed and engine rotations. The robustness of the algorithm is checked on three test data sets with 97 events of truck unloading. The reliability of event detection is about 90%, and false events recognition probability is 5%. The algorithm is efficient enough and its implementation on-line, as well for post-processing of historical data is possible.
Pavlo Krot; Pawel Sliwinski; Radoslaw Zimroz; Norbert Gomolla. The identification of operational cycles in the monitoring systems of underground vehicles. Measurement 2019, 151, 107111 .
AMA StylePavlo Krot, Pawel Sliwinski, Radoslaw Zimroz, Norbert Gomolla. The identification of operational cycles in the monitoring systems of underground vehicles. Measurement. 2019; 151 ():107111.
Chicago/Turabian StylePavlo Krot; Pawel Sliwinski; Radoslaw Zimroz; Norbert Gomolla. 2019. "The identification of operational cycles in the monitoring systems of underground vehicles." Measurement 151, no. : 107111.
The research goals of this work are to simulate the phase transformations in heat treatment of large-scale rolls of special alloy steels including deep cryogenic treatment (DCT) stage with experimental estimation of its influence on wear resistance of rolls. The adapted analytical models are introduced and applied for the calculation of phase transformations. Combination of finite-element models and experimental continuous cooling diagrams allowed determining the temperature and stress fields as well as each phase fraction in the special alloy steels 65Cr2Si3MoV, 50Cr5NiMoV and 70Cr3MnNiMoV at different stages of rolls manufacturing. Two short cycles of DCT conducted on samples showed increased by 39% wear resistance of 65Cr2Si3MoV alloy steel compared with its standard heat treatment schedule.
Pavlo Krot; Sergey Bobyr; Maxim Dedik. Simulation of backup rolls quenching with experimental study of deep cryogenic treatment. International Journal of Microstructure and Materials Properties 2017, 12, 259 .
AMA StylePavlo Krot, Sergey Bobyr, Maxim Dedik. Simulation of backup rolls quenching with experimental study of deep cryogenic treatment. International Journal of Microstructure and Materials Properties. 2017; 12 (3/4):259.
Chicago/Turabian StylePavlo Krot; Sergey Bobyr; Maxim Dedik. 2017. "Simulation of backup rolls quenching with experimental study of deep cryogenic treatment." International Journal of Microstructure and Materials Properties 12, no. 3/4: 259.
The research goals of this work are to simulate the phase transformations in heat treatment of large-scale rolls of special alloy steels including deep cryogenic treatment (DCT) stage with experimental estimation of its influence on wear resistance of rolls. The adapted analytical models are introduced and applied for the calculation of phase transformations. Combination of finite-element models and experimental continuous cooling diagrams allowed determining the temperature and stress fields as well as each phase fraction in the special alloy steels 65Cr2Si3MoV, 50Cr5NiMoV and 70Cr3MnNiMoV at different stages of rolls manufacturing. Two short cycles of DCT conducted on samples showed increased by 39% wear resistance of 65Cr2Si3MoV alloy steel compared with its standard heat treatment schedule.
Pavlo Krot; Сергей Владимирович Бобырь; Maxim Dedik. Simulation of backup rolls quenching with experimental study of deep cryogenic treatment. International Journal of Microstructure and Materials Properties 2017, 12, 259 .
AMA StylePavlo Krot, Сергей Владимирович Бобырь, Maxim Dedik. Simulation of backup rolls quenching with experimental study of deep cryogenic treatment. International Journal of Microstructure and Materials Properties. 2017; 12 (3/4):259.
Chicago/Turabian StylePavlo Krot; Сергей Владимирович Бобырь; Maxim Dedik. 2017. "Simulation of backup rolls quenching with experimental study of deep cryogenic treatment." International Journal of Microstructure and Materials Properties 12, no. 3/4: 259.
This paper intends to describe nonlinear effects occurring in rolling mills dynamics. That is necessarily for vibrations damping and reliable diagnostics of rolling mills equipment under non-stationary working conditions. Three types of nonlinear effects are investigated taking place in drivelines and stands of different design, namely, transient torsional vibrations in hot rolling mills, chatter vibrations in tandem cold rolling mills and parametrical vibrations in high-speed wire and rod rolling mills. The procedure is proposed for natural frequencies identification when short transient torque signals restrict application of the Fourier transform. Examples are given on using nonlinear effects for wear diagnostics and vibrations control based on natural frequencies and modes analysis of multi-body systems.
Pavlo Krot; Vladimir V. Korennoy. Vibration Diagnostics of Rolling Mills Based on Nonlinear Effects in Dynamics. Bulletin of the National Technical University «KhPI» Series: Dynamics and Strength of Machines 2016, 118 -123.
AMA StylePavlo Krot, Vladimir V. Korennoy. Vibration Diagnostics of Rolling Mills Based on Nonlinear Effects in Dynamics. Bulletin of the National Technical University «KhPI» Series: Dynamics and Strength of Machines. 2016; (26):118-123.
Chicago/Turabian StylePavlo Krot; Vladimir V. Korennoy. 2016. "Vibration Diagnostics of Rolling Mills Based on Nonlinear Effects in Dynamics." Bulletin of the National Technical University «KhPI» Series: Dynamics and Strength of Machines , no. 26: 118-123.
Uncertainty of technology and equipment parameters is particular for the rolling mills dynamics. Contact friction produces a wide band stochastic impacts which cause chatter vibration in the middle and higher natural frequencies range (100–1000 Hz) of the mill. Strip elasto-plastic deformation as a nonlinear spring in the stand depends on random technology parameters (rolls bending, strip tensions, mill speed). The transfer functions were used for principal mode distribution and chatter vibrations control in the cold rolling mills. The second cause of uncertainty is wear (backlashes) which makes drive train an essentially nonlinear system. The backlashes gaps and rolling loads are always uncertain at the beginning of transient process in the hot rolling mills causing dynamic torques scattering in the multibody drive trains. The low frequency (10–20 Hz) torsional vibrations are investigated. The output dynamic load distribution parameters were obtained. Statistical aspects of the mill control and diagnostics are discussed.
Paul V. Krot. Statistical Dynamics of the Rolling Mills. IUTAM Symposium on Multiscale Modelling of Fatigue, Damage and Fracture in Smart Materials 2011, 429 -442.
AMA StylePaul V. Krot. Statistical Dynamics of the Rolling Mills. IUTAM Symposium on Multiscale Modelling of Fatigue, Damage and Fracture in Smart Materials. 2011; ():429-442.
Chicago/Turabian StylePaul V. Krot. 2011. "Statistical Dynamics of the Rolling Mills." IUTAM Symposium on Multiscale Modelling of Fatigue, Damage and Fracture in Smart Materials , no. : 429-442.
The excessive dynamic loads and shock vibration are particular for the hot rolling mills equipment. An attempt to reduce torque amplification factor (TAF) has been done for the roughing stands of a wide strip hot rolling mill. Drive acceleration method was used in order to close the open backlashes gaps before transient process begins. This method is usually implemented for the reversing stands without gearboxes. But for the drive trains which include heavy gearboxes with the big rotating inertias it could be applied effectively partly. The second mode of torsional vibration may significantly change TAF in the different couplings. Therefore torque active control by motor speed regulation should be rearranged. Industry measurements of the torques and vibrations have been carried out to prove drive acceleration method to torsional vibration active control in dependence on drive trains design.
Pavlo Krot. Transient torsional vibrations control in the geared drive trains of the hot rolling mills. 2009 IEEE International Conference on Control Applications 2009, 1368 -1373.
AMA StylePavlo Krot. Transient torsional vibrations control in the geared drive trains of the hot rolling mills. 2009 IEEE International Conference on Control Applications. 2009; ():1368-1373.
Chicago/Turabian StylePavlo Krot. 2009. "Transient torsional vibrations control in the geared drive trains of the hot rolling mills." 2009 IEEE International Conference on Control Applications , no. : 1368-1373.