High-speed Rolling Research Articles

MUELLER BRASS C38500

Abstract Mueller Brass C38500 is a wrought copper-zinc-lead alloy (leaded brass) that is suitable for high-speed screw machining applications and moderate thread rolling. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as heat treating, machining, and joining. Filing Code: Cu-924. Producer or source: Mueller Brass Company.

Power Loss Estimation and Thermal Analysis of an Aero-Engine Cylindrical Roller Bearing

High-speed rolling element bearings for aircraft engines are custom-made components and operate under high temperature conditions owing to the elevated rotational speeds and loads. Therefore, assessing the various heat generation sources and mechanisms is worth investigating to accurately quantify the overall power loss within the bearing. In this context, a numerical parametric study was performed to determine and locate various power losses inside an aero-engine cylindrical roller bearing. Then, a thermal network model based on Ohm’s law was developed to estimate the operating temperatures of the bearing elements. A series of experiments was carried out on a high-speed rolling element bearing test rig to validate the numerical predictions, such as bearing component temperatures and overall power loss at specific operating conditions. The numerical predictions based on a hybrid approach showed good agreement with the experimental data.

World Experience in Creating Mathematical Models of Air Springs: Advantages and Disadvantages

Purpose. Taking into account the production and commissioning of modern high-speed rolling stock, the authors are aimed to analyze the currently created mathematical models describing the dynamic behavior of the air spring, systematize them and consider the advantages and disadvantages of each model type. Methodology. For the analysis, a comparative chronological method was used, which makes it possible to trace the development of several points of view, concepts, theories. In accordance with the adopted decision equations, the existing models of air springs were divided into three groups: mechanical, thermodynamic and finite-elements. When analyzing mathematical models, the influence of a number of parameters on the dynamic behavior of the air spring, such as disturbing force frequency, heat transfer, nonlinear characteristics of materials, the shape of the membrane, etc., was considered. Findings. A feature of mechanical models is the determination of input parameters based on the analysis of experimental results, requires access to complex measuring equipment and must be performed for each new model of an air spring separately. Unlike mechanical models, which allow taking into account the damping effect of an air spring in the horizontal and vertical direction, thermodynamic models are mainly focused on studying the dynamic behavior of an air spring in the vertical direction. The use of the finite element method makes it possible to most accurately reproduce the dynamic behavior of an air spring, however, it requires significant expenditures of time and effort to create a finite element model and perform calculations. Originality. Mathematical models of the dynamic behavior of an air spring are systematized, and the importance of their study in conjunction with a spatial mathematical model of high-speed rolling stock is emphasized. Practical value. The analysis of the mathematical models of the dynamic behavior of the air spring shows the ways of their further improvement, indicates the possibility of their use in the spatial mathematical model of the rolling stock in accordance with the tasks set. It will allow, even at the design stage of high-speed rolling stock, to evaluate its dynamic characteristic and traffic safety indicators when interacting with a railway track.

Effect of induction remelting on microstructure and properties of hot spraying coating for high speed rolling mill bearings

Effect of induction remelting on microstructure and properties of hot spraying coating for high speed rolling mill bearings

MODELING OF A SYSTEM FOR AUTOMATIC REGULATION OF THE TENSION MODE IN THE ROUGHING GROUP OF STANDS OF A CONTINUOUS SECTION MIL

The subject of the research is automatic control system modeling features for tensioning of stands roughing group, which takes into account changes in the rolling speed at exit of the previous stand and entrance to the next stand. Control systems for high-speed rolling on section mills are the most critical systems, since the trouble-free operation of rolling mill largely depends on their work. Rolling speed control is understood to mean tension regulation in the roughing group of stands and stabilization of the rolling loop in the finishing groups. The influence of such technological factors as uneven heating of blanks, change in the crimping mode in stands, etc. leads to the appearance of tension or back-up forces, deviation of rolled loop from the specified values. Tension rolling, in contrast to loop rolling, is a stable rolling mode. However, (at significant values of tension in the rolled products) such a rolling mode leads to different thicknesses of the finished product. The loop rolling mode is an unstable mode and is impossible without automatic control systems. Both in the tension rolling mode and in the free rolling mode with a loop, it is necessary to study automatic control systems in order to determine the possibilities of compensating for disturbing influences and obtaining rolled products of the given accuracy. Therefore, the main task of the automatic control system is to maintain the rolling mode with the lowest possible tension. To achieve this goal, direct control of the tension of the rolled strip with modern technical means is rather difficult, and the operation of tension control systems is based on indirect methods of measuring it, and the study of the system efficiency is reduced to modeling the process itself. The developed model consists of three stands and two inter-stand spaces, since it takes into account changes in rolling speed at the exit of previous stand and the entrance to the next stand. It is due to this that adequate simulation results are obtained that are close to the real rolling process.
 Keywords: automation, rolls, stand, inter-stand spacing, modeling, loop tension, rolling mill, roughing group.

Effect of materials and surfaces on frictional heating resistance of high-speed high-load rolling bearings

Many engineering applications require rolling bearings to run at very high rolling speeds and under very high loads. In ball bearings, even if the rolling/sliding ratio is very low (normally below 3%) because of the very high rolling speeds (∼40 m/s) the sliding speeds between the balls and raceways can reach locally very high values (∼1.35 m/s). The combination of these high sliding speeds and high contact pressures (up to 3 GPa) can induce lubricant film failures and increase the risk of adhesive wear between the surfaces (i.e. seizure). This process can be gradual or catastrophic, depending on the operating and lubrication conditions of the contacts. In this article, an investigation is presented where the effects of the material properties and surface topography on the adhesive wear resistance are addressed. The investigation applies a recently developed model for surface damage prediction from frictional heating, compared with a to-be-published seizure resistance experimental study. Three steels are included in the research together with different surface roughness. The results show the best material and roughness combination to maximise the seizure resistance of the surfaces.

2D and 3D numerical and experimental analyses ofthe aerodynamic effects of air fences on a high-speed train

This perusal surveys the design criteria indispensable for fences that are installed alongside the high-speed railway tracks to protect the passing high-speed rolling stock under strong side winds. Using a numerical code based on Lattice Boltzmann Method (LBM) it is attempted to initially investigate the airflow behavior behind the fences. A variety of geometries for air fences in a two-dimensional space are compared. A wind tunnel test is performed to verify the numerical results. The three-dimensional flow patterns around the German Intercity Express (ICE3) high-speed train with and without the air fences are numerically examined to be more realistic. It is found that the presence of the fences has a significant impact on decreasing the intensity of the airflow above the train. The edges on the top of the fences cause more reduction in the velocity of air flowing above the train.

ОДНО КРИТИЧЕСКОЕ ЗАМЕЧАНИЕ К ИСПЫТАНИЯМ БУКСОВЫХ ПОДШИПНИКОВЫХ УЗЛОВ СКОРОСТНОГО И ВЫСОКОСКОРОСТНОГО ПОДВИЖНОГО ЖЕЛЕЗНОДОРОЖНОГО СОСТАВА

The release of rolling stock and its components for free circulation on the territory of the Customs Union shall be allowed only upon conformity confirmation with the requirements of Technical Regu lations ТР ТС 001/2011 and ТР ТС 002/2011. For conformity assessment of such critical safety related rolling stock component as axle-box bearings the supporting standard GOST 32769–2014 (or GOST 18572–2014) is used. For traditional and high-speed rolling stock the standard foresees changing of the single run duration in the course of full-scale bench tests of axle-box bearings for determination of certification parameter. The example of the test runs of a high-speed train showed that during the time of such single run (in accordance with the standard) the axle-box bearings fail to reach the maxi- mum values of the certification parameters, which can result in unreliable conformity assessment of the axle-box bearings with the safety requirements. With the purpose to increase the reliability of the assessment of the maximum temperature of the axle-box bearings for traditional and high-speed rolling stock and also to bring the conditions of the bench tests of axle-box bearings to the full-scale operating conditions as possible, we propose to consider in the supporting standard the possibility of upholding the duration of single runs while conducting bench tests unchanged, independent of the design speed of the rolling stock

New bench for testing the reliability of windows and doors of passenger cars

The article describes a new bench for testing the reliability of passenger car windows and doors. The bench can be used in various industries, mainly in transport engineering, as well as in the construction industry. This bench is functionally designed to test the entire product (windows or doors), as well as to determine the service life of individual mechanisms of this product. In contrast to the known analogs, the new bench for testing the reliability of windows and doors allows testing under the influence of variable aerodynamic pressure arising from the operation of windows and doors on moving objects, for example on high-speed transport. Specially developed test method is proposed on this bench, which allows simulating alternating aerodynamic effects on windows and doors that occur when a train passes tunnels or when trains in opposite directions diverge at high speeds. Thanks to this, bench tests can serve as an actual addition to the existing methods of testing windows and doors of modern high-speed rolling stock.

High Speed Roll Caster for Aluminum Alloy

Two types of high-speed twin-roll casters and a single-roll caster equipped with a scraper were proposed. One of the twin-roll casters is a vertical-type high-speed twin-roll caster, and the other twin-roll caster is an unequal-diameter twin-roll caster. The vertical-type high-speed twin-roll caster can cast strip at speeds of up to 120 m/min. The unequal-diameter twin-roll caster casts strip at speeds up to 60 m/min. The unequal-diameter twin-roll caster is superior to the vertical-type high-speed twin-roll caster at the point of conveyance of the cast strip. A single-roll caster equipped with a scraper can cast strip without center-line segregation at speeds of up to 40 m/min. The use of a copper alloy roll and the non-use of a parting material enable high-speed roll casting. Since the roll loads of these casters are smaller than 0.1 kN/mm, soft copper alloy roll can be used. The strip does not stick to the roll without the parting material because of the use of the copper alloy roll with high thermal conductivity and the small roll load. The cooling rate near the surface is higher than 2000 °C/s.

MUELLER BRASS C36000

Abstract Mueller Brass C36000 is a wrought, Cu-Zn-Pb alloy (leaded brass) that is suitable for high-speed screw machining applications and moderate thread rolling. On the basis of strength alone, it can safely be substituted for leaded steel in many applications. UNS C36000 is the most important commercial copper alloy, surpassing all but copper itself in terms of annual consumption. This datasheet provides information on composition, physical properties, microstructure, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as heat treating and machining. Filing Code: Cu-918. Producer or source: Mueller Brass Company.

Texture and mechanical properties of Cu alloy by cryogenic high-speed rolling

Cryogenic high-speed rolling (CHSR), where the sheet cooled in liquid nitrogen is supplied to rolls rotating at 1500 m/min at room temperature, was applied to several Cu alloys. After the CHSR, mechanical strength was improved with texture transition from the ‘copper-type’ to the ‘brass-type’ components. This trend was clearly observed in the case of Cu alloys with intermediate SFE. It is considered that the deformation mode changed from the dislocation slip to deformation twinning and shear banding under high Z parameter conditions of CHSR. It is also found that CHSR can improve the strength of Cu alloys with less decrease in electrical conductivity.

Effect of minimum friction coefficient on vibration stability in cold rolling mill

Mill chatter is a major restriction in the high-speed rolling of high-strength and thin strips. To maintain mill stability, the friction coefficient must be kept within a certain range. Unfortunately, there is no model to calculate the lower limit of the friction. In this paper, a new model is developed to capture the minimum friction coefficient. This model is proposed based on mixed lubrication theory and monotonicity analysis in the friction curve. The verification results showed that the established model could accurately predict the minimum friction and the friction balance in tandem rolling mills. The model was utilized to design the optimal rolling conditions to expand the stability range of the friction and improve mill vibration stability.

Investigation of lubricant supply in rolling point contacts under starved conditions using CFD simulations

High friction and wear in rolling bearings are prevented by a lubricating film, which separates the contacting surfaces. In rolling contacts with limited lubricant supply, the film thickness decreases at high rolling speeds, as more lubricant is displaced than replenished. This lubricant depletion is known as starvation and may induce mixed lubrication due to a low film thickness. When estimating the bearing lifetime, a fully flooded lubrication, i.e. an unlimited lubricant supply, is usually assumed. This leads to an overestimation of film thickness in operating ranges where starvation occurs. Thus, considering the onset of starvation is crucial to reduce the risk of premature bearing failures due to high friction and wear in the mixed lubrication regime. Therefore, this contribution presents a method, based on computational fluid dynamics (CFD) simulations, to calculate the onset of starvation in oil lubricated point contacts.

An accurate stop control method of high-speed rolling machine for automobile production line using laser ranging and two positon close loop

The high-speed rolling machine is a key equipment in the automatic production line of automobile body-in-white welding. This article focuses on analyzing a method for accurately stopping the high-speed rolling machine using laser distance measurement. Firstly, through the analysis of the movement process, the calculation method of the length of each period in the 7-stage S-type acceleration and deceleration in the movement of the high-speed rolling machine is given; secondly, the system control theory model of the measurement and control system is established to analyze the dual-position closed-loop strategy The method of realizing the accurate stopping of the high-speed rolling machine; finally, the accurate stopping control method of the high-speed rolling machine proposed in this paper was verified by building an experimental system and developing the corresponding control program.

Microstructural, Mechanical, and Tribological Properties of Mg-3Al-1Sn-1Nd-Mn Alloy

In this study, Mg-3Al-1Sn-1Nd-Mn alloy was produced by low-pressure die casting method and homogenization heat treated (HHT) at 400 °C for 16 hrs. Microstructural characterization of the alloy was done by XRF, XRD, LOM and SEM–EDS analyses. The microstructure of the alloy was composed of α-Mg, Al2Nd and Al11Nd3 phases. Hot rolling was applied to the HHT alloy at two different speeds 13.78 rpm [low speed rolling (LSR)] and 26.96 rpm [high-speed rolling (HSR)] at 350 °C. Microstructural changes were also carried out by LOM and SEM analyses. Mechanical properties (hardness and tensile properties) and wear performances of HHT, LSR and HSR samples were compared. SEM fractography was conducted on tension test samples to visualize the deformation and fracture behaviors. Also, worn surfaces of samples were investigated by SEM–EDS analysis. Abrasive, oxidation and delamination mechanisms were observed for worn surfaces of samples. To sum up, the mechanical properties of the HSR sample were higher compared to the HHT and LSR samples, and the wear rate was lower than HHT and LSR samples.

Numerical investigation of effects on replenishment in rolling point contacts using CFD simulations

A lubricating film prevents a rolling bearing from high friction and wear by separating the contacting surfaces. In grease lubricated contacts the bled oil induces a hydrodynamic film formation. At high rolling speeds, more bled oil is displaced than replenished, which leads to lubricant starvation. To predict the film formation under starvation, the lubricant supply by replenishment must be determined. However, the effects on oil replenishment are not fully clarified. In particular, the effects of oil wettability as well as the available bled oil amount on the replenishment are not sufficiently investigated. Therefore, in this contribution the oil flow around a rolling point contact is examined under limited oil volume and in dependence of oil wettability, using CFD simulations.

Prediction of coefficient of friction for different surface topography in mixed-EHL regime

The operation of concentrated contacts observed in gearboxes, rolling element bearings, and cams/followers of valve etc of several machinery and mechanical systems in the mixed-elastohydrodynamic lubrication (mixed-EHL) regime is one of the key reasons for occurring the incident of surface contact fatigue. Due to significant asperity interactions in the mixed-EHL regime, the friction coefficient is profoundly affected by the surface topography of mating bodies. Thus, exploration of role of surface topography on coefficient of friction in mixed-EHL regime is a vital issue. This work proposed a model for investigating the effect of different surface topography on the coefficient of friction of concentrated contacts under mixed-EHL regime. The results achieved with the proposed mixed-EHL model are validated by performing rolling/sliding experiments. A good match is found between experimental and predicted coefficient of friction. Based on the investigation, it is also concluded that a surface with small fraction of summits can operate in boundary lubrication regime at high-load and low-speed conditions. A surface with lower correlation length exhibit elastic-plastic deformation at higher coefficient of friction. High value of friction coefficient is observed for rough surface (S q > 0.5 μm) at even higher rolling speed (1 m s−1).

Structural design of high-speed rolling bearing test rig spindle with cantilever

Purpose The purpose of this paper is to introduce the structure design process of the cantilever spindle with limited installation space and wishing to increase its critical speed. Design/methodology/approach In this paper, the finite element method was used to analyze the influence of the supporting stiffness and the structure of the spindle on the critical speed, and then the structure of the spindle was designed; moreover, the experiment was accomplished and the experiment results show that the spindle can work stably. Findings Through analyzing the influence of the supporting stiffness and the structure of the spindle on the critical speed, the following conclusions could be obtained: the shape of the first-mode is the bend vibration of the cantilever of the spindle; the first-order critical speed of the spindle gradually decreases with the diameter and length of the cantilever increasing; the first-order critical speed of the spindle increases with the depth and diameter of the blind hole increasing; and the experiment was accomplished and the experiment results show that the spindle can work stably. Originality/value In this paper, the finite element method was used to design the spindle of the testing machine, and satisfactory results were obtained. It can provide a theoretical reference for the design of a similar spindle.

Modeling and experimental study of tire deformation characteristics under high-speed rolling condition

Tire rolling deformation consists of valuable information for vehicle control and tire development applications. To gain insight into this deformation, both model-based and tire sensor-based approaches have been investigated in previous studies. However, existing tire models oversimplified the pressure distribution in the tire-road contact due to a lack of related experiment data especially for deformations of the tire at high rolling speeds. Meanwhile, the tire sensing method requires extensive experiments and cannot be directly used within vehicle simulations. For resolving the above issues, this paper proposes a combined approach for studying tire rolling deformation. Specifically, the flexible ring tire model (FRTM) is extended with a realistic, dynamic pressure distribution to provide more accurate predictions of the rolling tire deformation under various operation conditions. Meanwhile, a three-dimensional high-speed stereo vision system has been set up together with an optimized digital image correlation (DIC) method to measure the deformation of high-speed rolling tires. The experimental results reveal that rolling tires experience an eccentric deformation and an anti-symmetric deformation in the radial and tangential directions, respectively. Additionally, it was observed that the vertical load has a more substantial influence than the tire pressure on rolling deformation. The capability of the improved ring tire model to describe these observed phenomena has been validated through comparisons between simulations and measurements.