High-speed Rolling Research Articles

Research on Anti-Wear Properties of Nano-Lubricated High-Speed Rolling Bearings under Various Working Conditions

Research on Anti-Wear Properties of Nano-Lubricated High-Speed Rolling Bearings under Various Working Conditions

Tribodynamic Modelling of High-Speed Rolling Element Bearings in Flexible Multi-Body Environments

This study presents a new flexible dynamic model for drive systems comprising lubricated bearings operating under conditions representative of electrified vehicle powertrains. The multi-physics approach importantly accounts for the tribological phenomena at the roller–race conjunction and models their effect on shaft-bearing system dynamics. This is achieved by embedding a non-linear lubricated bearing model within a flexible system level model; this is something which has not, to the authors’ knowledge, been reported on hitherto. The elastohydrodynamic (EHL) film is shown to increase contact deflection, leading to increased contact forces and total bearing stiffness as rotational speeds increase. Results show that for a 68 Nm hub motor operating up to 21,000 rpm, the input bearing EHL film reaches a thickness of 4.15 μm. The lubricant entrainment increases the roller–race contact deflection, causing the contact stiffness to increase non-linearly with speed. The contribution of the lubricant film leads to a 16.6% greater bearing stiffness at 21,000 rpm when compared to conventional dry-bearing modelling methods used in current multi-body dynamic software. This new methodology leads to more accurate dynamic response of high-speed systems necessary for the next generation of electrified vehicles.

Вейвлет-преобразования в задачах контроля и диагностики автоколебаний стана холодной прокатки

Self-excited oscillations remain a frequent problem of cold rolling of thin strips. When self-oscillations occur, the amplitude increases by a jump of more than a hundred times, that is from 2–3 m/s2 to 200–250 m/s2. Oscillation frequencies (from 100 to 500 Hz, i.e. the number of loading cycles) can reach several thousands per a few seconds. Intense self-oscillations normally occur on thin strips with a thickness of less than 1 mm and high rolling speeds. The control of the occurrence of self-oscillations includes special systems, according to the level of vibrations or technological parameters, for example, by fluctuations in the tension of the strip. In control systems, classical methods include the decomposition of the controlled signal into a Fourier series. For stationary processes, Fourier series decomposition provides complete information about the signal structure and is sufficient to diagnose the technical condition of machines and mechanisms. As for a nonstationary non-harmonic signal, the information about the spectral composition of the diagnostic signal is insufficient, since it does not allow for determining the moment of occurrence of an undesirable process. In metallurgy and rolling production, processes are frequently not stationary. The cold rolling process is continuous, but discrete. It takes 5–6 minutes to roll one coil. The process of selfoscillation, even when using control systems, can last no more than 2–3 seconds. A high frequency of vibrations and a high level of stress can lead to the formation of cracks in the elements of the mill stands, for example, CVC plates. A signal conversion wavelet can become an alternative way of monitoring and diagnostics. If the FFT allows you to determine the presence of self-oscillations only in the developed state, the wavelet transform allows you to determine the origin of the selfoscillation process at low oscillation amplitudes. It also allows you to determine it in the absence of fluctuations by changing the signal of the technological parameters.

Автоколебания клетей стана тандема холодной прокатки 2000 Магнитогорского металлургического комбината

One of the problems of cold rolling of thin strips is self-excited chatter vibrations, which lead to the appearance of various defects. High-frequency self-oscillations can lead to defects related to surface quality, low-frequency ones with high amplitude levels can lead to gusts of thin bands or even severe accidents of the rolling mill itself. As a rule, self–oscillations occur suddenly at high rolling speeds, more than 20 m / s and thin strips, the thickness is usually around 300-700 microns. For the normal operation of the rolling mill, it is necessary to use special systems for monitoring the vibration state and preventing the occurrence of self-oscillations. The control system for exceeding the critical vibration level generates signals from the automated control system of the mill to eliminate self-oscillations. The critical vibration level is determined by the spectral composition using the fast Fourier transform (FFT). When self-oscillations occur, lowfrequency components from 5 to 20 Hz prevail, frequencies in the range of the third octave from 100 to 200 Hz and frequencies of the fifth octave from 400 to 800 Hz. The cold rolling mill 2000 of the Magnitogorsk Iron and Steel Works combines a tandem five-cell mill and a continuous etching unit. There is no regular vibration monitoring system at the mill, warning and elimination of self-oscillations occurs in manual mode. With the use of research vibration equipment, experimental studies have been conducted on the possibility of using technological parameters to control and prevent the occurrence of self-oscillations. The moment of occurrence of self-oscillations can be controlled by the vibrations of the hydraulic tensioning device (GNU) of the mill. Processing of the vibration displacement signal of the measuring channel of the GNU FFT

Адаптивна система управління швидкісним режимом вільної прокатки з нечітким регулятором

The best high-speed mode of rolling mills is the mode of free rolling with loop formation in finishing groups of cages. Stabilization of the loop is carried out by the control system of the rotation frequency of the rolls of rolling cages based on the information of the sensor of the position of the loop. The increase in the loop depends on the frequency of rotation of the rolls of adjacent cages and the coefficient of extraction of the rolled product in the cage following the adjustable gap. To set up the system, it is necessary to know the numerical characteristics of the influences that disturb and affect the size of the rolling loop. The change in the rotation frequency of the main drive of the cages during the stabilization of the size of the rolling loop in the intercellular gap of the cages of the finishing group of the continuous rolling condition was studied. The change in the rotation frequency of the rolls characterizes the total effects of the rolling mode on the size of the loop. Research have shown that in a non-stationary realization it is possible to single out a trend that is described by a completely deterministic dependence, and to conduct an analysis of a random stationary realization with respect to this trend. A structural diagram of the circuit for regulating the position of the rolling loop was developed. This scheme includes: an electric wire with a current loop, a speed loop, a speed regulator, a rolling loop, a loop position regulator, a compensator of disturbing influences. The compensator is based on the Fuzzy controller and produces a control effect depending on the inconsistency in the loop control circuit. In this way, the low-frequency disturbance component at the rolling speed, which can reach 10% of the rolling speed, is monitored and compensated. The obtained data of changes value of the loop without and with a compensating circuit. The size of the loop in the system without a compensating circuit when rolling a thicker rear part of the rolled product reaches the maximum permissible size. This does not happen in a system with a compensating circuit. It is possible to stabilize the value of the loop in a given range either by increasing the regulator coefficient, thereby worsening the dynamics of the entire multi-link control system of the high-speed rolling mode, or by using the proposed method of adaptive disturbance compensation.

Energy Efficiency of High-Speed Railways

The world is becoming more dependent on energy resources, which translates into political dependency on energy-exported states. This will significantly impact the economy, transport, and the environment around the world. Railway transport is becoming an essential mode of transportation because it can operate on an electrified network and has zero carbon emissions. High-Speed Railways (HSR) is an energy-intensive transport system, and it is important economically and environmentally to reduce the amount of used energy. This study examined high-speed rail from an energy efficiency point of view and found factors that can significantly reduce the energy consumption of high-speed rail. This research aims to answer the question that motivated this research: what fundamental factors affect the energy consumption of the selected HSR systems? It estimated the dynamic changes in the total energy consumption for seven HSR systems from 2010-2017 and benchmarked the most energy efficient HSR systems. The non-radial Data Envelopment Analyses methodology has been used to fulfil this research. To conduct complex statistical analyses, IBM SPSS has been applied. The main findings have shown that the decrease in vehicle mass, improved design of high-speed rolling stock and increased occupancy of trains will support the reduction of energy consumption by high-speed railways. The changes in energy consumption strongly correlate with the type of high-speed rolling stock and operational strategies. The expected outcomes of this research will contribute to developing and advancing more sustainable HSR systems. This research will support train operators in making decisions when acquiring new trains and assess the benefits of acceleration in modernising the current rolling stock.

Minimization of dynamic changes in the tension of long products behind the outlet cage in rolling stock production in coils

Purpose. Justification of technical solutions as to the reduction of the amplitude and reduction of the dynamic change duration in the tension of the rolling stock at the exit of the output cage when moving to winding a new layer to an acceptable level in terms of its effect on the resulting profile of the rolled product through the control of the rotation frequency of an output cage. Methodology. The conducted research was based on a complex model of the process of rolled steel winding with a Garrett-type winder and the tension of rolled steel in the area of the exit cage-winder. To control the actual amount of tension at the output cage exit, it is suggested to use the amount of free deflection of the rolled steel directly behind the cage. The research was carried out by simulating the process of rolled steel winding according to the basic control scheme and control schemes that predict the influence on both drives, i.e. the winder drive and the output cage drive according to the actual value of tension, in various combinations with further analysis and comparison of the obtained results. Findings. It was established that the correction for the deviation of the actual rolling tension in the finishing cage-winder area from the specified value of the winding current of the winder electric drive does not eliminate rolling tension when switching to the next layer winding and the oscillating form of the transition process, which are characteristic of the basic rolling winding scheme. In turn, the correction of the rotation frequency of the output cage rolls drive reduces the amplitude of the roll tension jerk by almost half with a simultaneous reduction in the time of the transition process and readjustment when switching to a new layer winding. Originality. It has been shown for the first time that the introduction of the roll tension control circuit by correcting the high-speed rolling mode of the output cage ensures minimization of dynamic changes in the rolled steel tension when switching to a new layer winding and reduces the probability of local tightening of rolled steel profile. Practical value. The use of the described technical solutions in the control system of the section of rolled products winding of the small-grade wire mill DSDS 250/150-6 PJSC ArcelorMittal Kryvyi Rih ensures the improvement of the commercial properties of the winding of rolled products produced on the rolling mill.

Работоспособность опор контактной сети на высокоскоростных железнодорожных магистралях

Purpose: To perform working efficiency analysis of catenary separately standing reinforced-concrete supports in high-speed railway conditions, to develop measures and constructive solutions of the supports of increased reliability and durability. Methods: Analysis of typical constructive solutions according to Russia State Standard GOST 19330-99 given their exploitation experience, the use of numerical calculation methods involving calculation programs. Results: The disadvantages of being applied structures of catenary supports on railways with the use of steel and reinforced concrete are analyzed. The calculations of typical reinforced-concrete support bearing capacity and rigidity according to GOST 19330-99 with the use of SCAD computing complex for the effect of vital climatic and exploitational burdens, including ones from wind pressure at high-speed rolling stock motion trains at the speed of 300 km/h, are made. Innovative support construction has been developed which includes pillar of reinforced concrete, fiber-reinforced concrete or steel on reinforced-concrete foundation, the construction is combined with alignment-free mounting method to ensure the impermeability of construction being united parts. Practical significance: The reserves for working efficiency of typical separately-standing reinforced-concrete catenary supports in the conditions of high–speed railway trunk St. Petersburg - Moscow on project documentation basis are revealed. The possibility of pressure perception by supports from wind flow at train motion of 300 km/h speed has been established. The application of innovative combined steel-concrete structure of catenary support construction and its mounting ways are proposed. The use of support mounting and construction new way would allow to reduce support mounting laboriousness as well as to rise support reliability and durability in exploitation changing conditions.

Solar panel surface dirt detection and removal based on arduino color recognition

Color sensing is a technique for identifying physical changes in materials based on appearance assessment. Dirt deposition on solar panels can change their physical appearance and performance. Considering that dirt accumulation on solar panels needs monitoring to make efficient cleaning schedules, reduce unnecessary costs, and optimize solar panel output generation. Color sensing can achieve fast, accurate, and economical dirt detection, unlike the use of robotic cameras, mathematical formulae, and considering varying output current and voltage methods. Here, we introduce a method that detects and removes dirt on solar panels based on TCS3200 and Arduino Uno components. The approach targets (i.) Panel color measurement, calibration, threshold selection process, (ii.) comparison of color measurement values, and (iii.) align further calibration in response to discoloration of solar panels. This method aims to correct the dirt detection methods previously in use. Hence, a high-speed rolling brush arrangement is designed to improve the cleaning of the solar panel without using water. Further investigations of the panel's color may require some improvement in terms of increasing the sensitivity of the color sensor even with increased distance from the solar panel. Combining multiple color sensors may also be necessary.

Rolling speed dependence of cryogenic rollability of bimodal non-basal textured AZ31 Mg alloy sheet

The rolling speed dependence of cryogenic rollability of bimodal non-basal textured AZ31 Mg alloy sheet has been investigated through multi-pass rolling experiments with a constant 5% thickness reduction per pass and characterization experiments via X-ray diffractometer (XRD) and electron backscatter diffraction (EBSD) techniques. The chosen rolling speeds include 30 mm/s (low-speed), 300 mm/s (mediate-speed) and 600 mm/s (high-speed). Rolling results show that the accumulated thickness reduction (ATE) of low-speed rolled sheet reaches up to about 22.6%, which is 58.0% bigger than that (14.3%) of high-speed rolled sheet. This means that the rollability of studied sheet under high-speed rolling is obviously worse than that under low-speed rolling. Characterization results confirm that high-speed rolled sheet possesses the smallest tilted angle (about 16.3°) between the maximum intensity point in (0002) pole figure and normal direction (ND) by comparison with other two sheets, leading to the enhancement of difficulty to accommodate the thickness plastic strain during rolling at liquid-nitrogen temperature. Moreover, high-speed rolling can not only realize the saturation of {10-12} extension twin (ET) nucleation at the beginning of cryogenic rolling, but also promote the growth of {10-12} ET nuclei. This issue benefits in improving the frequency of occurrence of Ortho-position (OP) -typed {10-12} ET variant interaction, which would block the motion of dislocation slip effectively. The deteriorated rollability of high-speed rolled sheet is mainly attributed to these two issues.

Center Line Globular Structure of Strip Cast Using High Speed Twin Roll Caster

Formation of a centerline globular structure in an aluminum alloy strip cast using a vertical type high-speed twin-roll caster was investigated. The theory that the crystals form at tip of the nozzle and are conveyed to the roll gap was investigated by roll casting using a cooling slope and clad-strip-casting in this study. In high-speed roll casting, the center of the strip thickness is semisolid, and the temperature gradient in the thickness direction is small. The latent heat of the semisolid metal heats the dendrite structure, which is divided by melting. The dendrite structure was divided as in thixocasting, which is the mechanism of formation of a globular crystal form. The zone of the semisolid metal becomes narrow as the roll load increases or the pouring temperature of the molten metal decreases. As result, the zone containing globular crystal structures becomes thinner.

Fault dynamic model of high-speed rolling bearing by a compound displacement excitation function considering the effect of defect roughness

Most of bearing fault dynamic models use simple displacement excitation functions to characterize the fault excitations from defects, and do not consider the influence of high-speed, dynamic radial clearance and transmission path, which brings the simulation signal a big gap with the measured signal. To solve these issues, this paper proposes a compound displacement excitation function by considering the influence of defect roughness, then constructs a new fault dynamic model of high-speed angular contact ball bearing (ACBB) by using the proposed displacement excitation function and introducing the effects of high-speed, dynamic radial clearance and transmission path. The proposed ACBB fault dynamic model is numerically solved for obtaining the dynamic responses under different fault sizes and speeds, then their characteristics in time and frequency domains are analyzed. The comparative results indicate that the simulation signals generated by the proposed model are closer to the measured signals, compared with those obtained by the typical bearing fault dynamic models. Finally, the correctness and superiority of the proposed model are verified by the experiments on faulty high-speed ACBBs.

Thermo-mechanical-abrasive coupling analysis of solid rubber tire under high-speed rolling

High friction and large deformation under high-speed sideslip landing conditions cause rapid heating and severe abrasion of aircraft tire, which seriously threatens landing safety. Therefore, theories of energy dissipation and transient heat transfer are discussed. A thermo-mechanical-abrasive (TMA) coupling analysis method is proposed for solving the thermomechanical problem. Laws of temperature and abrasion under different slip angles are revealed experimentally. Results show that sideslip conditions lead to increase of friction energy dissipation and wear as well as an asymmetric distribution of temperature field; Considering abrasion can effectively improve prediction accuracy of thermomechanical analysis (an increase of 27.65%), the predicted temperature and abrasion profile are in good agreement with the experiment data.

Roller Bearing Skidding for Aero-Engine Applications: All-Steel Versus Hybrid Bearings

Abstract Roller bearings operating under light loads may suffer from skidding. The latter is more pronounced as the speed increases and may result in extensive wear and reduced service life of the bearing. The main objective of this study is to analyze skidding occurrence in a custom-made all-steel M50 bearing and a hybrid roller bearing subjected to the same operating conditions. The test bearings have a bore diameter of 90 mm, an outer diameter of 125 mm and 26 rollers. The hybrid bearing features silicon nitride (Si3N4) rollers and steel rings (M50 outer ring and M50-NIL inner ring). The bearings feature special channels to allow for under race lubrication of the bearing components in relative motion. A suite of sensors were used and installed to detect skidding and monitor the overall performance of the test bearing such as vibrations and temperature. The effect of the radial applied load, shaft rotational speed, and oil flowrate on roller skidding has been investigated and discussed. Slip ratio for each of the bearings under various speed–load combinations was also determined and analyzed. Turbo-Oil 2380 was used to lubricate the test bearings at a constant temperature of 77 °C. Tests were conducted on a high-speed rolling bearing test rig, and data were recorded using a 24-bit data acquisition system.

Effect of Roll Material on Strip Solidification between the Rolls of a Vertical-Type High-Speed Twin-Roll Caster

Tool steel for hot working is usually used for the rolls of conventional twin-roll casters for aluminum alloys. In a vertical high-speed twin-roll caster, copper rolls are used to rapidly solidify the aluminum alloys and to increase the casting speed, since the thermal conductivity of copper is higher than that of tool steel. However, the degree of superiority of copper rolls over steel rolls is not clear. In the present study, the effect of the roll material on strip solidification between the rolls of a vertical high-speed twin-roll caster was investigated by inserting a thermocouple in the strip during casting. The Al-4.8%Mg alloy was used, since it does not stick to the steel rolls in the absence of a parting material. Both copper rolls and mild steel rolls were used. The cooling rate, the supercooling of the liquidus temperature, and the temperature of the strip cast using the copper rolls were superior to those of that cast using the mild steel rolls. The copper rolls were better than the steel rolls in terms of achieving high-speed roll casting, rapid solidification of the strip, and high productivity.

Braking forces of a traction linear induction motor with an adjustable resistance of a short-circuite winding of the secondary element

Background: The study of the properties of linear traction drives for new types of rolling stock seems to be an urgent task. Linear motors are multifunctional and are capable of providing both traction and braking of promising high-speed rolling stock.
 Aim: Investigation of the braking characteristics of an adjustable traction linear induction motor with variable resistance by a short-circuited winding of the secondary element.
 Methods: Analytical methods have been used to obtain relations for calculating the braking forces of an adjustable linear induction motor with a short-circuited winding of the secondary element.
 Results: The obtained ratios made it possible to calculate the braking forces of linear induction motors.
 Conclusion: The results of calculating the braking forces of adjustable linear induction motors make it possible to reasonably choose the braking modes of a new type of rolling stock.

A high-accuracy SINS attitude update algorithm based on Legendre polynomial

The large-acceleration motion of HFV (hypersonic flight vehicle), the high-speed rolling of spinning missile, and the large-maneuver flight of fighter aircraft has put forward higher performance demand for SINS (strapdown inertial navigation system). The high-accuracy positing will be realized under the high-dynamic maneuver environment after decreasing measurement error of IMU (inertial measurement unit), meanwhile the algorithm of SINS must be improved. The conventional algorithm calculates the flight attitude with determining the compensation term of coning error, after ignoring the high-order term of the Bortz equation. To improve the algorithm accuracy of SINS under high-dynamic maneuver environment, a high-accuracy algorithm, which uses Legendre polynomial to complete angular velocity function approximation and takes the numerical method of quaternion differential equation as core, is proposed herein. The high-order coning error is compensated in the numerical solving period in the proposed novel algorithm, because no approximation exists in deducing process. The attitude calculating simulations are finished in coning motion condition and high-dynamic maneuver condition respectively. Compared with the quadruple-cross-product compensation algorithm which has the highest accuracy at present, the attitude error of proposed algorithm is less than its 1/3 in coning motion condition. And algorithm accuracy is raised an order of magnitude under the high-dynamic maneuver environment. The high-accuracy algorithm based on Legendre polynomial has reference significance for accurate positing of future HFV, atomic gyroscope INS research and high-accuracy algorithm design of SINS.

Effect of Al addition and annealing on the microstructure evolution of Mg-3Sn Mg alloy subjected to high-speed rolling

The microstructure evolution of Mg-3Sn, Mg-3Sn-3Al-Zn (ATZ331), and Mg-3Sn-6Al-Zn (ATZ631) alloys during high-speed rolling (HSR) and annealing was studied. High-speed rolling was carried out on the three alloys at a rolling speed of 1100 m/min, a rolling temperature of 400 °C, and a reduction of 40% during a single pass. The results showed that the microstructure of the samples after HSR contained many twins and was dominated by {10−12} extension twins (ETs) and supplemented by {10−11} contraction twins (CTs) and {10−11}-{10−12} double twins (DTs). After adding Al, the content of these different types of twins was reduced. The twinning fraction decreased significantly with 3 wt% Al addition, while the twinning fraction decreased slightly with 6 wt% Al addition. The high-speed rolled alloys were annealed at 370 °C for 1 min, 2 min, 3 min, 5 min, and 8 min. When the annealing time was 1 min, the recrystallization fraction of the ATZ631 alloy was low, indicating that increasing the Al content to 6 wt% inhibited recrystallization. When the annealing time increased to 3 min, the recrystallized grains in the ATZ631 alloy grew, indicating that the grain growth progressed faster in this alloy. When the annealing time was 8 min, the grain size of the three alloys grew. The electron backscattered diffraction (EBSD) results of the alloy annealed for 8 min showed that the twin fraction in the annealed state was lower than that after high-speed rolling. In addition with the increase in Al content, the twin fraction decreased. During high-speed rolling, the maximum intensity also increased with an increase in Al content, were 22.72, 25.09, and 26.35, and the texture of the annealed alloy was weakened. The Al addition also increased the maximum intensity.

An extra long stringless pendulum

A 2.7 m long stringless pendulum was set up to measure the coefficient of rolling friction of various balls, at higher rolling speeds than usually observed with a short stringless pendulum. The arrangement is easy to set up and makes an impressive classroom demonstration as well as an interesting laboratory experiment.

Сложная пространственная геометрия криволинейных участков трассы высокоскоростных железнодорожных магистралей

Purpose: The paper poses some promising trends of modern projection science development for high-speed railway plan and profile. The main objective of the trends is to critically rethink the provisions of the existing regulatory design base of the projection. The question on inadmissibility of the arrangement of complex spatial geometry sections — the sections of coincidence of a vertical curve in a profile and a passage curve in a plan — is one of such provisions. Methods: In the frames of the conducted research, a theoretical approach to the determination of force impacts at the section of complex spatial geometry is proposed. Results: It is established that force impact value is caused by vertical curve direction (convex or concave), as well as by calculated value of outstanding acceleration in being considered curve, Studies of the influence of sections with complex spatial geometry on the dynamics of high-speed rolling stock motion show that at certain combination of circular and vertical curve radii for motion various speeds, it is possible to minimize negative dynamic effects caused by the presence of complex spatial geometry section. Practical importance: As a result of the work, it was found that at speeds of 350 km/h or more, the superimposition of a vertical curve in the profile and a passage curve in the plan is acceptable without applying additional requirements to the curve parameters. The radius of the circular curve should be increased by 30-60% at speeds of less than 350 km/h.