Smooth Rolling Research Articles

Edge drop and high spot control of hot-rolled non-oriented electrical steel strip by taper roll shifting strategy

ABSTRACTA hot rolling schedule of non-oriented electrical steel of the same strip width suffers from severe uneven roll wear, which leads to high spots and excessive edge drop. To eliminate these shape defects, a ‘keep-smooth’ shifting strategy of the taper roll was proposed: the strategy aimed at a smooth roll wear contour and was achieved by a varying-rate shifting mode. A roll wear model was developed to predict the evolution of the wear contour under different shifting parameters, and the optimal parameters were obtained by the adaptive particle swarm optimisation algorithm. The effect of the new shifting strategy on the strip profile was studied based on a 3D finite element rolling model. The industrial application verified the new taper roll shifting strategy, as both the edge drop and high spots were alleviated and the rolling length of a schedule was extended by about 10 km.

RESEARCH OF THE BEHAVIOR OF MACROSTRUCTURE DEFECTS OF THE PRE-DEFORMED CONTINUOUS CAST BILLETS DURING ROLLING

The most significant trend in recent decades in the field of continuous casting of steel billets is a partial transfer of the process of deformation of the exposure to the field of complete solidification (rolling mill) in the area of two-phase (solid-liquid)state (technological line of CCM). However, the implementation of such two-stage deformation of the continuous cast ingot leads to the need for changes to the methodology of physical simulation of the behavior of defects (surface and bulk) in the course of the subsequent rolling, first and foremost, in terms of the correct choice of their geometric shape and spatial orientation. The paper presents the results of a study of the influence of spatial orientation of the surface defects and continuity of the macrostructure of the metal axial region deformed in the line of the continuous casting machine using layered physical models. An experimental study performed in the conditions of deformation of reduced billets by two schemes with rolling simulation scale1:5: in smooth rolls, simulating the process of groоvelles rolling as applied to the first two stands of the crimp group of medium-section mill 300; in the first and second pairs of rectangular grooves of breakdown stand of the mill 500/370 of PJSC “Donetsk Metal Rolling Plant”. According to the multiplicity of the problem, the universal design of physical models was developed to simulate the spatial location of both surface and internal defects. Studies have shown that in case of rolling of physical models with extract ratio over 2.0 and an angle of misalignment defects imitators close to 60° their complete “healing” is possible. In turn, decrease in the angle to 30° contributes to greater extraction of the defect-simulator and only a small decrease in their width. In the case of total misalignment of defect-simulators (angle 90°) there is a broadening of the defects and their deposition to the initial length after tilting by 90°. The obtained experimental data allowed understanding of the mechanisms of “healing” defects integrity of metal depending on magnitude of the total extracts, the angle of misalignment of the longitudinal axis of the defect with the rolling direction and the distance of their occurrence from the longitudinal-transverse plane of symmetry.

Behavior of Structural Defects of Already-Deformed Continuous-Cast Bar on Rolling

In the continuous casting of steel ingots, the most significant trend over the last few decades has been the partial transfer of deformation processes from the region of complete solidification (the rolling mill) to the region characterized by a two-phase solid–liquid state (the continuous-casting line). However, such two-stage deformation of the continuous-cast ingot entails changes in the physical modeling of the behavior of surface and interior defects in subsequent rolling. In particular, modifications are required in selecting the geometry and spatial orientation of the defects. In the present work, the influence of the surface-defect orientation and central macrostructure (pore content) of bar billet deformed in the continuous-casting line is investigated by means of laminar physical models. The deformation conditions of reduced-scale (1: 5) continuous- cast billet are studied experimentally in two rolling configurations: (1) the use of smooth rollers to simulate groove-free rolling in the first two stands of the cogging group in the 350 continuous medium-bar mill; (2) rolling in the first and second pairs of straight grooves in the cogging stand of the 500/370 mill at PAO Donetskii Metallurgicheskii Zavod. Since this is a multivariant problem, a universal design has been developed for the physical model, so as to simulate the spatial configuration of both surface and internal defects. The research shows that, in rolling the physical models with an extension coefficient greater than 2.0 and practically 60° inclination of the simulated defects to the rolling axis, their complete elimination is possible. In turn, decreasing the inclination to 30° facilitates greater extension of the simulated defects and only slightly reduces their width. When the inclination of the simulated defects to the rolling axis is 90° (complete lack of coaxiality), broadening of the defects and their compression to the initial length is only observed after 90° rotation. The experimental data provide insights regarding the elimination of internal defects (pores) in the metal as a function of the total extension, the inclination of the defects’ longitudinal axis to the rolling direction, and their distance from the longitudinal–transverse symmetry plane.

DEVELOPING MODES TO OBTAIN DEFORMED SEMI-FINISHED PRODUCTS FROM EXPERIMENTAL SCANDIUM CONTAINING ALUMINUM ALLOY AND STUDYING THEIR MECHANICAL PROPERTIES

The paper demonstrates the urgency of studies focused on creating new Al-Mg alloys doped with scandium and featuring by an advantageous combination of operational and mechanical properties such as weldability, corrosion resistance and sufficient strength. In production conditions, 560×1360×4520 mm flat ingots were obtained from an experimental scandium-containing alloy. They were cut into billets with a maximum thickness of 40 mm and then heat treatment and sheet rolling modes were developed for them and tested. The DUO 330 mill with smooth rolls having an initial diameter of 330 mm and a barrel width of 540 mm was used as rolling equipment. Experimental studies consisting in blank preparation for rolling (homogenization annealing and face milling), hot rolling at 450 °C, cold rolling to a thickness of 3 mm and annealing of cold-deformed semi-finished products at 350 °C for 3 hours allowed making deformed semi-finished products by various drafting patterns at rolling that were subjected to heat treatment. The maximum total degree of deformation during billet rolling to the 3 mm thickness was 92,5 %, and the draw ratio per pass changed from 1,04 to 1,2. The LFM400 400 kN universal test machine as per GOST 1497-84 was used to determine mechanical properties of deformed and annealed semi-finished products of various thicknesses made of an experimental alloy and identify regularities of their changes depending on the total degree of deformation during rolling. It was found that when rolling strips of an experimental scandiumcontaining aluminum alloy the ultimate tensile strength and yield strength of the metal grow, and the percentage elongation decreases with an increase in the total degree of deformation. This corresponds to the general ideas of metal forming theory. The mechanical analysis of semi-finished products showed that the level of strength and plastic properties is quite high, wherein the ultimate tensile strength reaches 453–481 MPa, yield strength – 429–457 MPa, and percentage elongation – 3,8-5,0 % for cold-deformed samples. Annealing made it possible to increase percentage elongation values to 14–16 % at sufficiently high yield strength (up to 277 MPa). The results of the conducted studies were used to develop casting, rolling and annealing modes for making semi-finished products of the Al–Mg alloy sparingly doped with scandium within 0,10–0,14 % that will be used when mastering machining technologies in production.

Sensor Fusion Algorithm by Complementary Filter for Attitude Estimation of Quadrotor with Low-Cost IMU

This paper proposes a sensor fusion algorithm by complementary filter technique for attitude estimation of quadrotor UAV using low-cost MEMS IMU. Angular rate from gyroscope tend to drift over a time while accelerometer data is commonly effected with environmental noise. Therefore, high frequency gyroscope signal and low frequency accelerometer signal is fused using complementary filter algorithm. The complementary filter scaling factor K1=0.98 and K2=0.02 are used to merge both gyro and accelerometer. The results show that the smooth roll, pitch and yaw attitude angle can be obtained from the low cost IMU by using proposed sensor fusion algorithm.

Impact of roll compaction design, process parameters, and material deformation behaviour on ribbon relative density

Ribbons from microcrystalline cellulose (MCC), mannitol, and their 50:50% mixture were produced using the roll compactors AlexanderWerk BT120, Hosokawa Alpine Pharmapaktor C250, L.B. Bohle BRC 25, and Gerteis Mini-Pactor in the frame of multilevel full factorial experimental plans. The specific compaction force (SCF)/hydraulic pressure (HP), gap width (GW), roll speed, and fraction of MCC were analyzed as quantitative factors, whereas the roll surface and sealing system were examined as qualitative factors. Ribbon relative density was investigated as response of the models. The SCF/HP is found to be the most significant factor in each model. A significant inverse effect of the GW is obtained in the models of AlexanderWerk BT120, Pharmapaktor C250, and BRC 25 roll compactors, using smooth rolls. The principle of the establishment of a conversion factor (cf) is introduced based on the obtained data sets of AlexanderWerk BT120 and Mini-Pactor. This can facilitate the transfer of a roll compaction process between different types of roll compactors.

A Laboratory-Scale Tempering and Milling Method for Grain Sorghum

Abstract. The current commercial milling process for pigmented sorghum leads to inconsistent milling quality and performance. Proper pretreatment of sorghum may improve the milling performance. The effects of cold water, hot water, and steam tempering of sorghum on the milling performance and flour quality were investigated in this study. A tabletop roller mill system that had five break rolls and two smooth rolls was used. The millstream output at different stages of roller milling was used to evaluate the effectiveness of the conditioning treatments. Steamed sorghum had high bran yield due to toughening of the bran, which allowed gradual scraping of the endosperm from the bran. Flour yield was not significantly different among the pretreatments. Flour crude fiber content of the 1 min steam treated sorghum was 1.28% ±0.09%, which was significantly higher than that of cold water treated sorghum (0.87% ±0.19%). The damaged starch content in the milled flour was highest in the cold water treated (5.96% ±0.24%) sorghum, and steam treatment resulted in lower damaged starch content (3.63% to 4.18%). Steam treatment resulted in flour with more convex and circular particles compared to the other treatments, indicating better separation of starch granules from the endosperm. Steam treatment of sorghum kernels at high temperature and pressure led to better separation of bran and endosperm without negatively impacting flour quality. Steam tempering could be a better pretreatment process for milling sorghum for food purposes. Keywords: Flour properties, Milling, Sorghum, Tempering.

Alternating Sign Rolling Technology in Grooved Rolls for Nonferrous Metal Plate Billets

Results are given for a study of rolling plate metal by technology including rolling in grooved rolls and levelling on a smooth barrel. Results of computer modeling and analysis of the Lode–Nadai coefficient show that during rolling in grooved rolls two types of deformation-compression arise in a billet cross section, i.e., compression in inclined areas and shear in ridged zones. This picture of stress distribution is most favorable since compressive strain leads to “healing” of possible metal discontinuities, but shear deformation leads to intense working of the original metal structure. During rolling in the first pair of smooth rolls deformation compressive in nature predominates, and in the second pair of rolls it is deformation alternating in nature. In any billet vertical section, metal contact with rolls occurs on both surfaces, i.e., upper and lower, which leads to compression in ridge zones, but to tension in inclined sections. Analysis of the results of metallographic studies points to the benefits for rolling in grooved rolls in the plan of preparing a metal fine-grained isotropic structure. The use of grooved rolls leads to significant strengthening of L63 brass compared with using smooth rolls with an identical overall degree of deformation.

Laboratory Controlled Rolling of Microalloyed Steel for Production of Seamless Tubes

Using the laboratory rolling mill with smooth rolls, piercing, as well as rolling in a pilger mill of the seamless tubes with diameter 273 mm from the HSLA steel microalloyed with vanadium steel was simulated. Influence of the wall thickness (6.3 – 40 mm) and finish rolling temperature on the final structural and mechanical properties was investigated. Necessary temperatures of the phase transformations in the course of cooling were determined by dilatometric tests. Based on the dilatometry results, finish rolling temperatures were reduced. Lower rolling temperatures yielded in a relative grain refinement. Effect of the finish rolling temperature did not have any marked impact on the tensile tests results. Strength properties decreased only slightly with the increasing wall thickness and the plastic properties were not influenced significantly by this parameter. The positive effect of the reduced finishing temperature appeared markedly in the results of impact tests performed at room temperature only. Notch toughness was increased by approx. 25 % in the case of the wall thickness of not less than 20 mm.

The Study of the Microstructure of the Metal after Rolling Thick Workpieces of Nonferrous Metals and Alloys in Relief and Smooth Rolls

One of the ways to improve the quality of steel production by rolling is the creation of additional streams of the metal flow, i.e. intensification of shear deformation not only in longitudinal but also in transverse direction. From the review of scientific-technical and patent literature it is known that to improve the quality of products when rolling usually use a system of alternating projections and depressions, which is created on the surface of the wide faces of slab or on work rolls. In this case, along with deformation in altitudinal and longitudinal directions, the conditions for deformation of the metal in the transverse direction, which has a positive effect on reducing the anisotropy of properties. Knowing the advantages of rolling with additional shear deformations, we have developed energy-saving technology of plate billets rolling of non-ferrous metals and alloys, allowing to obtain a uniform fine-grained structure throughout the volume of the workpiece, and designed two new constructions of the pair of work rolls with embossed surface as an annular groove, forming a trapezoidal protrusions and depressions alternating each other along the entire length of the barrel (the first pair to unequal treatment of the ledge to the depression and the second pair with equal respect to the ledge to the depression) to implement this technology in practice. In this paper were described results of investigations of microstructure evolution of copper alloys by rolling on the proposed technology in the relief rolls and according to the current technology in smooth rolls.

The Role of Preliminary Heat Treatment in the Formation of Ultrafine-Grained Structure in the Implementation of the Combined Process "Rolling - Equal Channel Angular Pressing"

In recent years was developed a number of new methods of processing of metals by pressure aimed at obtaining metal with sub-ultrafine-grained structure, the basic principle of which is the realization in the process of deformation of simple shear scheme. One of those ways is pressing blanks in matrices of different designs, in particular in equal-channel step die. However, this method has a significant disadvantage - it can’t be used for deforming of lengthy billets. Another disadvantage of this method of deformation is that it does not provide the continuity of the pressing process. For removing these shortcomings at the Department "Metal Forming" of Karaganda state industrial University was developed a combined process "Rolling-pressing" using equal channel step matrix with calibrated and smooth rolls. This work investigates the impact of the proposed combined process "rolling-pressing", and also preliminary and final heat treatment during the implementation of this combined process on the evolution of microstructure and mechanical properties of copper alloy. Obtained in the course of these studies, the results indicate that the proposed technology can be recommended for implementation in production to produce blanks of ferrous and non-ferrous metals and alloys with ultrafine-grained structure and high level of mechanical properties.

Determination of the Nip Angle in Roller Compactors With Serrated Rolls

In roller compaction, the nip angle defines the critical transition interface between the slip and nip regions which is used to model material densification behavior and the properties of compacted ribbons. Current methods to determine the nip angle require either sophisticated instrumentation on smooth rolls or input parameters that are difficult to obtain experimentally. In this study, a practical method to determine nip angles for serrated rolls was developed based on mass balance considerations established around the nip region. Experimental input relating to roll geometry, powder density, and mass output from the compactor were required and they could be obtained reliably. The calculated nip angles were validated against those obtained from physical measurements during actual roll compaction. These nip angles were in agreement for various powder formulations containing plastic and brittle materials. The nip angles ranged from 4° to 12° and decreased significantly when the proportion of brittle material increased. Nip angles were also calculated using the widely used Johanson model. However, wall friction measurement on serrated roll surfaces could be impractical. The Johanson model-derived nip angles could differ by 3°-8° just by altering the roughness of the reference wall and this had compromised their reliability.

Comparison of point foot, collisional and smooth rolling contact models on the bifurcations and stability of bipedal walking

Traditional biped walkers based on passive dynamic walking usually have flat or circular feet. This foot contact may be modelled with an effective rocker – represented as a roll-over shape – to describe the function of the knee–ankle–foot complex in human ambulation. Mahmoodi et al. has represented this roll-over shape as a polygon with a discretised set of collisions. In this paper point foot, collisional and smooth rolling contact models are compared. An approach based on the Lagrangian mechanics is used to formulate the equations for the swing phase that conserves mechanical energy. Qualitative insight can be gained by studying the bifurcation diagrams of gait descriptors such as average velocity, step period, mechanical energy and inter-leg angle for different gain and length values for the feet, as well as different mass and length ratios. The results from the three approaches are compared and discussed. In the case of a rolling disk, the collisional contact model gives a negligible energy loss; inco...

Multiscale structural changes of atomic order in severely deformed industrial aluminum

The regularities of multiscale structural changes in the atomic order of the aluminum alloy AD-1 after a severe cold plastic deformation by conventional rolling in smooth rolls or in rolls with relief recesses favorable for shear deformation have been investigated. It has been found that there are four types of structural fractions that differ in scale and perfection of atomic order: crystallographic planes with a long-range order; nanoscale fragments of the planes (D = 100–300 A) with an incipient long-range order; smaller groups of atoms (D = 20–30 A) of amorphized structure; and the least ordered structural fraction of intercluster medium, keeping only a short-range atomic order (2–3 interatomic distances, 10 A). The presence of diffuse halo bands in the region of intense Debye lines indicates phase transitions of the order → disorder type with the formation of one to three groups of amorphous clusters with the dominance, in the nanometer scale, of the atomic order characteristic of the family of planes (111), (220), and (311) of crystalline aluminum. We have found a dynamic phase transition with the changing crystallographic order of aluminum, with the matrix structure of a face-centered cubic (FCC) lattice, in the form of nanosized local groups of atoms, that is, the deformation clusters of aluminum with a simple cubic K6 lattice. In the case of conventional rolling, the development of large clusters 50–500 A in size is observed; however, in the use of rolls with relief recesses, the difference in the sizes of the clusters is one half as much: 50–250 A. Based on the analysis of the integrated intensity of incoherent X-ray scattering by the samples, we have elucidated the nature of the lowest measured density for the sample subjected to conventional rolling, which consists in the volume concentration of disorderly arranged atoms, the highest of the compared structures, which indicates the formation therein of the greatest amount of fluctuation “voids.”

Анализ критериев эффективности для оценки редуцирования сляба по ширине

The choice of efficiency criteria of slab widthwise reduction is quite challenging. The criterion should fairly reflect the information about the on-going process of study and its trends, the measurable parameters should be available for measurement. Only in this case the criterion can be used to assign an effective technology of slab reduction. The paper deeply analyzes the formulas presented by many authors for calculating the efficiency criterion, which were created to analyze the reduction considering the importance of various parameters. Using the finite element method slabs of different widths were rolled in vertical grooved rolls with the subsequent horizontal reduction in smooth horizontal rolls. Based on the geometric parameters of the simulation results the calculation of criteria for the analyzed formulas is presented. Based on the calculation results of the formulas being analyzed, their peculiarities and field of application are emphasized. A formula is proposed for the efficiency criterion evaluation considering possible rolling options, i.e. rolling in vertical rolls only, rolling in vertical rolls with subsequent smoothing passage, and rolling in vertical rolls with subsequent horizontal reduction. Recommendations are provided on the formulas selection for a faithful description of the process considering possible rolling options.

PRECISION OF MODELING OF METAL FORMING BY FINITE ELEMENTS METHOD

The paper describes the study of influence of finite element form that is used for partitioning of rectangular strip in simulation of rolling process with the use of smooth rolls. The accuracy of determining of velocity in longitudinal direction has been analyzed at each point of the deformation zone. Simulation of the rolling process has been performed using the penalty functions method and ESVDeform software package that was developed at the Chair of Metal Forming of DSTU. The results of the analysis allow recommending the 3D finite elements of rectangular form for practical use. It grants high accuracy of velocities prediction. The tetrahedral elements have been recommended to use in the cases when the accuracy of velocities prediction is not very important, but a large uneven strain distribution is presented in deformation zone.

The development of near‐surface microstructures during hot rolling of aluminum–magnesium alloys in relation to work roll topography

The effect of the work roll topography on the surface deformation of aluminum alloys during hot rolling was examined with the use of a rolling tribo‐simulator. AISI 52100 steel work rolls with two surface conditions, smooth (polished to a surface roughness (Ra) of 0.01 µm) and rough (WC‐coated with a surface roughness (Ra) of 5.68 µm), were used to hot roll Al‐Mg alloy samples under similar conditions for a rolling schedule of 10 passes. The surface of the rolled samples reflected the work roll surface morphology. Surface damage for the smooth rolled samples included cracks, while shingles and grooves were observed on the rough rolled samples. Cross‐sectional examination revealed cracks extended to depths above 8 µm for the rough rolled samples, while for the smooth rolled samples, cracks were 1.5 µm deep. The oxide‐rich near‐surface layer formed on the rough rolled surfaces was discontinuous. In contrast, the near‐surface generated by the smooth roll was continuous, and near‐surface damage was uniform in comparison. A nanocrystalline grain structure was observed at the near‐surface region beneath the oxide‐rich area for the smooth rolled samples, which extended to shingles on the rough rolled samples. The nanocrystalline nature of the near‐surface region was attributed to the high strains imposed by the work roll, while the effect of the rough roll was surmised to include the formation of shingles, the redistribution of surface oxide, and the enhancement of the near‐surface damage. Copyright © 2015 John Wiley & Sons, Ltd.

A Computational Chemistry Approach for Investigation of Low Friction Mechanisms Based on FEP Film with Functionalized SiO<sub>2</sub> Nanoparticles

To improve the fuel efficiency of automobile internal combustion engines, we investigated the fundamental mechanism of friction reduction within engine moving parts. A new coating was designed by introducing SiO2 nanoparticles in FEP film. The SiO2 nanoparticles were functionalized with hydrophobic fluoroalkyl units on their surface to create additional low friction property. Universal Surface Tester friction measurements revealed a significant reduction of the friction coefficient with increasing number of hydrophobic fluoroalkyl units for SiO2 surface functionalization. To clarify the friction reduction mechanisms by the functionalization of SiO2 nanoparticles, a quantum chemical calculation was carried out. The result indicates that an attractive force occurs between nanoparticle Si atoms and polymer F atoms, while by adding fluoroalkyl units on the SiO2 nanoparticle surface, this force changes to repulsive. By performing a molecular dynamics simulation of a shear model between FEP film and SiO2 nanoparticles, we observed a decrease of friction force with increasing fluoroalkyl units which lead smooth rolling motion of nanoparticles, thus confirming the repulsive effect of nanoparticle functionalization. We conclude that fluoroalkyl units on the SiO2 surface play an important role in creating a repulsive force between nanoparticle and FEP film which lead to low friction coefficient.

An experimental investigation on the influence of lubrication on roughness transfer in skin-pass rolling of steel strip

Skin-pass rolling (or temper rolling) is usually the final process in the production of cold-rolled steel sheets. In operation, skin-pass rolling is performed with roughened rolls, using a lubricant with a very low lubricating ability. However, relatively few studies in the literature have examined the effect of lubrication in skin-pass rolling. In this paper, the influence of lubrication on elongation and roughness transfer in skin-pass rolling is investigated by experimental rolling tests in which the relationship between lubrication behavior and the roll radius is clarified. As in a previous study of smooth rolls, the results with large, operational size rolls can be explained convincingly by height characterization parameters and are considered to be reasonable. It was also found that some characteristics of skin-pass rolling related to lubrication are not properly simulated using small radius, laboratory size rolls due to the insufficient contact length between the rolls and the workpiece.

Construction of Weak Expansive Red Clay on Dongxin Expressway in Hunan Province, China

AbstractRed clay is a common roadbed filler in China. In southern China, because of the high natural moisture content, it is hard to make enough compact clay in the process of roadbed filling construction, and it shrinks and cracks when dehydrated. This article compares the domestic regional soil properties of red clay in China, analyzing its physical properties, composition, chemical properties, and water characteristics, and the filler used in the construction of the Dongxin expressway. Swelling of the red clay packing was also observed. According to laboratory tests, field test analyses, and settlement observation tests, when using red clay as road filler, the use of a smooth bump grinding wheel and rolling of subgrade compaction works best for controlling moisture content, with the wet compaction test method within the range of ±5% of optimum moisture content. This method can ensure the strength and stability of the subgrade to provide guidance for the use of red clay in construction.