Rolling System Research Articles

Analytical solution for nonlinear vertical vibration model of mill roll system based on improved complexification averaging method

Rolling mill is the core equipment in modern iron and steel industry, and the reliability of its mill roll system (MRS) is the key to ensure the rolling process with high precision, high speed, continuity and stability. However, the MRS possesses some features such as high nonlinearity, time variability and strong coupling. The vertical vibration easily happens in its working process. Nevertheless, the mathematical model of MRS is difficult to be established and hard to be solved. In this paper, the nonlinear dynamics theory and modern signal processing method were introduced to solve this difficult problem. A two degree of freedom (DOF) nonlinear vertical vibration model of MRS was established. And the model was analytically solved by using complexification averaging (CA) method. The solution error of CA method was thoroughly analyzed. Moreover, the CA method was improved by combining the fast empirical mode decomposition (FEMD) method. Research results indicate that the improved CA method presents a significant advantage in improving the solution precision, and can be used to solve strong nonlinear vibration system (NVS) with two DOF.

Stress and Springback Analyses of API X70 Pipeline Steel Under 3-Roller Bending via Finite Element Method

3-Roller bending is a widely applied manufacturing process, particularly in structural steel pipe industry. However, due to the difficulty and high cost of measuring stress distribution inside sheet material via traditional method, internal stress/strain response during forming is largely unexplored. The focuses of this study are two: (1) to map the radii of curvature as well as the stress inside the work piece during forming by utilizing the meshing mechanism of finite element method, and (2) to further provide some numeric guidelines for the configuration of the rolling system in order to improve production efficiency and product quality. The results of this study indicate that: (1) it is crucial to properly choose forming parameter in order to produce product with desired radii; (2) much like a gradual springback process, the radii of curvature gradually increase from the top roller to the exit-side bottom roller; (3) under the assumptions made in this study, to produce pipes with a specified diameter with varying configurations of the 3-roller system will not significantly change the final residual stress; and (4) finally, shifting of the neutral axis up to 2.0% of the thickness toward the compressing side during the forming process is observed.

Microstructural Evolution of Al-Mn Based Alloy Fabricated by Vertical-Type High-Speed Twin-Roll Casting

For decades, twin-roll casting has been applied for manufacturing aluminum alloy sheets. This conventional process contributes to make thin aluminum sheets from the molten metal directly. Recently, vertical-type high-speed twin-roll casting (HSTRC) has been developed with much higher casting speed rather than the horizontal-type. Some modifications such as feeding nozzle and water-cooling system of copper rolls contribute to increase cooling rates. This characteristic leads to many metallurgical advantages like grain refinement, super-saturation of alloying elements and fine distribution of secondary particles. The objective of this study is to investigate the constituent particles in HSTRC aluminum alloy. The commercial Al-Mn alloy strip was successfully fabricated by HSTRC. Clearly different microstructure was found in thickness direction. Many constituent particles observed along the grain boundaries/cell boundaries as well as inside of Al matrix on the surface area, while eutectic structure around globular grain boundaries was observed in mid-central area. The morphology as well as chemical compositions of the constituent particles were investigated.

Hybrid Calculations of Bending Deformations for 20 Roll Cold Rolling Mill

In multi-high mills, the slim fixed floating work rolls are supported by primary and secondary intermediate rolls and several supporting rolls mounted pairs-wise on supporting shafts. Over the eccentric adjustment of saddle assemblies and hydraulic adjustment device the roll gap adjusts the specific elastic bending deformation of the support system. Based on a hybrid calculation model the influence and limits of an active adjustment device for 20 roll mill will be presented. Thereby the bending deformations as well as the contact deformations of the complete system including the forming process in settings of the elementary plasticity theory (EPT) will be considered.The modeling of the bending deformations of the roll systems are based on FE-Beam elements. The flattening in the contact zone between the rolls will be formulated by a modified non-linear approach, according to Hertz-Johnson. The contact of the deformed zone is aligned in the discretized EPT-roll model by Alexander with Hitchcock-flattening. The iterative analysis of the compact models leads to “force-deformation-relations”, which provides the influence of the variation of the gap. The force-deformation-relations will be detailed discussed in parameter studies of a real 20 roll mill.

Vision-based automatic detection of steel surface defects in the cold rolling process: considering the influence of industrial liquids and surface textures

In the cold rolling process, automatic surface defect detection could be considered as an important technique to monitor product quality, and so far, substantial kinds of surface defects have been already successfully inspected. However, the interference of industrial liquids and produced surface textures has been rarely studied yet. To address this problem, the vision-based automatic detection method is proposed in this paper containing three main parts: (i) region extraction, (ii) defect detection, and (iii) industrial liquid quantification. Four sets of experiments are designed to verify the feasibility, accuracy, and stability of the proposed method. The results indicate that the proposed method can detect most cracks and scratches with the accuracy of more than 91 %. Also, the proposed method could accurately quantify the industrial liquids including their numbers (with the average accuracy of more than 90 %) and their sizes (with the accuracy of more than 91 %); it is therefore expected to be promising because it could be utilized to track the online running status of the rolling system and provide rolling system maintenance suggestions.

Legal Aspects of Technology Assessment and Systems Analysis in Sustainable Urban Development

Large-scale urban development, not to mention synthetic urbanization, will not remain sustainable absent structural changes to the normative and decision making framework that include rolling technology assessment and systems analysis. Technology policies need to be based on outcomes as well as on significant improvements in complexity management at critical stages of planning and implementation. This conclusion endures even if it requires limiting options of political decision making in open democratic societies through normative structural automatisms. Independent of political trends, social consensus almost everywhere favors a prioritization of energy efficiency, alternative energies, resource recycling, urban farming, cost- and time-effective public transportation, water economy, and extended product life. But public interest-driven decision making processes, legislation, and dispute resolution do not adequately take into account the acceleration of technological innovation on the one hand, and of environmental deterioration on the other hand. This paper exposes fundamental weaknesses and future needs for technology assessment drawing on European, American and global experiences. It highlights challenges to avoid possible crises of legitimacy and anti-technology groundswells of Luddite proportions as well as forgoing groundbreaking opportunities for an open knowledge society based on informed consent rather than state mandate.

Mechanism generating deviations in the rolling load and strip camber on the plate rolling mill

Both the support force inequality on both ends of the roll and the camber are common drawbacks, those were caused by the static indeterminacy of structure design, backlash and offset setting selection on the plate rolling mill. There are many technical literatures for analysing the reasons for generating of the strip camber, which are mainly the external factor analysis, however, the internal cause of the mill roll system is ignored. The negative effects of offset distance setting and side clearances of about 1 mm between the chocks and side surface of the housing window should be considered on the plate rolling mill. In reality, the primary cause of this deviation and the strip camber lies in the interaction between offset distance setting and cross of the rolls. The greater the offset setting value of the plate rolling mill, the greater the generation probability of pressure difference and the camber. Some measures, involving eliminating offset distance setting, effectively controlling the side clearances between chocks and housing window, eliminating initial cross and dynamic cross phenomenon, should be taken to maintain the rolls parallel and to prevent radically the support force inequality on both ends of the roll and strip camber.

Hybrid intelligent modelling and simulation for cold tandem rolling process

Dynamics of cold tandem rolling processes are difficult to be simulated with mechanism models due to their high non-linearities, multivariable and strong couplings, time-varying distributed parameters and so on. A novel hybrid intelligent dynamic modelling approach is proposed based on the combination of a linearised state space model derived from various mechanism equations, a case-based reasoning algorithm for multi-state space models selection, a genetic algorithm for optimisation of case attributes, an adaptive fractal filtering algorithm for the identification of state space model parameters, a neural network-based simulation error compensation model for the strip exit velocity. With actual data from a 2030 mm five-stand cold tandem rolling system of a steel plant, simulation experiments verify the effectiveness of the proposed approach. Furthermore, a rolling simulation system is developed based on the proposed model, and the virtual tandem rolling experiments with the simulation system also validate that the proposed model can accurately simulate the dynamics variation from different types of disturbances of cold tandem rolling processes.

Stability and capsizing analysis of nonlinear ship rolling in wind and stochastic beam seas

Considering the actual seaway condition, stability and capsizing of nonlinear ship rolling system in stochastic beam seas is of significant importance for voyage safety. Safe zone are defined in the phase space plan of the unperturbed Hamilton system to qualitatively distinguish ship motions as capsize and noncapsize. Capsize events are defined by solutions passing out of the safe zone. The probability of such an occurrence is studied by virtue of the random Melnikov function and the concept of phase space flux. In this paper, besides conventional wave excitation, the effect of wind load is also taken into account. The introduction of wind load will lead to asymmetry, in other words, it transforms the symmetric heteroclinic orbits into asymmetric homoclinic orbits. For asymmetric dynamical system, the orbital analytic solutions and its power spectrum are not readily available, and the technique of discrete time Fourier transformation (DTFT) is used. In the end, as verification of theoretical critical significant wave height, capsizing probability contour diagram is generated by means of numerical simulation. The contour diagram shows that these analytical methods provide reliable and predictive results about the likelihood of a vessel capsizing in a given seaway condition.

The Possibility of Manufacturing Long-Length Metal Products with Ultra-Fine Grain Structure by Combination of Strain Effects

It is shown that combination of strain effects leads to possessing the ultra-fine grain structure in carbon wire. The continuous method of wire deformation nanostructuring was developed on the basis of simultaneous applying of tension deformation by drawing, bending deformation when going through the system of rolls and torsional deformation on a continuously moving wire. One of the main advantages of the developed method is that various hardware devices and tools already applied for steel wire production can be used to implement this method thus simplifying its introduction to the current industrial equipment. The efficiency estimation of the developed continuous method of deformation nanostructuring was carried out using carbon wire with different carbon content. It is shown that the mechanical properties of the wire after combination of different kinds of strain can vary over a wide range. This method makes it possible to choose such modes of strain effect, which can provide the necessary combination of strength and ductile properties of carbon wire depending on its further processing modes and application.

Optimizing the production of steel with reduction by aluminum, in casting and rolling systems

Data on the metallurgical defects in pipe show that they may be due to nonmetallic oxide inclusions. Analysis of the formation of oxide inclusions from smelting to the continuous casting of steel shows that, in order to reduce the incidence of such defects, additional measures must be taken in the smelting and ladle treatment of the steel. Such measures reduce the content of oxide inclusions in the steel by half. The benefits of this approach are confirmed by the reduced rejection rate of the pipe on account of defects associated with the presence of nonmetallic inclusions.

Investigation of grease behavior under simple and complex displacement amplitudes conditions

Grease lubricants are extensively used in contacts, usually to reduce friction and wear. Under small amplitude sliding, as in rolling systems subject to vibration, there is significant lubricant decay. The present study analyses the fretting and reciprocating sliding response of a greased interface. Lubricant behavior is firstly investigated under small fretting amplitude to explore three domains: partial slip, scarce lubrication and full lubricated domain. Secondly, the purpose is to investigate the effect of introduction of intermittent reciprocating displacement amplitude on grease response. Friction and wear behaviors are investigated as a function of imposed small fretting displacement amplitude in both cases. The kinetics of formation and destruction of tribofilm under simple and complex displacement amplitudes is formalized through an energetic analysis.

FEATURES OF THE EFFECT OF COMBINING DIFFERENT KINDS OF PLASTIC DEFORMATION ON THE MICROSTRUCTURE GRINDING AND MECHANICAL PROPERTIES OF THE CARBON WIRE

Since the mechanical properties of metals and alloys with ultrafi negrained structure are very attractive from practical appliance one of the technology development approaches is the creation of continuous methods of severe plastic deformation. Implementation of current methods of nanostructuring to existing technological processes of metallurgical and steel wire production involves a number of limitations connected with the size of processed workpieces. The article shows the necessity of developing a method of continuous methods of severe plastic deformation which according to its technical and technological characteristics would be compatible with existing technological processes of metalware manufacture. Combining of diff erent kinds of plastic deformation is a perspective tendency. Carbon wire was chosen as an investigation object. Combination of external stress leads to enhancing the technological possibilities of drawing as the basic wire production operation to large extent. On the basis of combining drawing with bending and twisting new method for obtaining the ultra-fi ne grained structure in semi-product which is protected by the patent of the Russian Federation. The essence of the method is the simultaneous applying deformations of tension when drawing, bending when going through the system of rolls and torsional deformation on a conti nuously moving wire. Various hardware devices and tools already app lied for steel wire production can be used to implement this method thus simplifying its introduction to the current industrial equipment. Schematic diagram and description of the developed method are presented. Photographs of the carbon wire microstructure with diff erent carbon content after diff erent types of deformation eff ects are shown. It is proved that combining drawing with bending and twisting leads to carbon wire microstructure refi nement. It is shown that deformation combined eff ect on carbon wire allows to modify its mechanical pro per ties in a wide range, while matching its high strength and ductility.

Numerical Simulation of the Electroslag Casting With Liquid Metal for Producing Composite Roll

The electroslag casting with liquid metal (ESC LM) is a new technology for producing composite roll of high quality based on electroslag metallurgy. In the present work, a two‐dimensional quasi‐steady state mathematical model of just one half of the ESC LM facility is developed due to the axial symmetry. Influences of operating voltage and pouring temperature on the heat transfer of the composite roll system have been studied. The Lorentz forces and Joule heat are combined with the turbulent flow and energy equations via additional source terms in these equations by the user‐defined functions (UDF) based on Fluent software. Simulation results indicate that the distributions of electric potential, current density, Lorentz forces, and Joule heat are concentrated on the upper area of slag bath and a much shallower molten steel pool is obtained. By using the current carrying mold, the heat transfer from slag bath and superheat of the molten steel pool are lower than the conventional ESR process, which is beneficial to a vertical crystallization and an excellent bonding interface between the roll core and working layer of the composite roll. The study of this paper gives us a better understanding of the ESC LM process.

Microalloying of low-temperature pipe steel for coil production by casting and rolling

The microstructure of coils of pipe steel alloyed with niobium and titanium produced in a casting and rolling system is studied by means of an optical microscope and a transmission electron microscope. The mechanical properties of the steel coils are also investigated.

The Formation of Localized Atmospheric Vortices of Different Spatial Scales and Ordered Cloud Structures

The classical Rayleigh theory of convective instability of a viscous and heat conductive rotating atmospheric layer is generalized to the case of phase transitions of water vapor both for the precipitation convection (PC) and for the nonprecipitation (NPC) one. A principal difference is stated between moist convection and Rayleigh convection, on the one hand, and PC and NPC, on the other hand. In particular, the instability region on the plane of model parameters turned out to generally consist of two subregions, in one of which the localized axisymmetric disturbances with a tropical cyclone (hurricane) structure have the highest growth rate. In case of PC the ascending motions on the axis of symmetry correspond to such disturbances, in case of NPC a spontaneous growth of localized vortices both with ascending and descending motions on the axis is possible. Under other parameters values in case of PC spatially periodic cloud structures (convective rolls or closed cloud cells) have the highest growth rate and in case of NPC–mesoscale systems of convective rolls or mesoscale cloud clusters with annular cloud structures.

Analysis on dominant influencing factors of on-line life cycle in sink roll system and effective improved methods

The continuous hot-dip galvanizing line is performed by threading the steel strip through three rolls of the sink roll system (including sink roll, stabilizer roll and correcting roll) submerged in molen zinc. The premature failure of sleeves and bushings of the three rolls would result in increased cost of production and low production efficiency. According to the on-site investigation of Meishan Iron&Steel Ltd and theoretical analysis, it indicated that the dominant influencing factor of online life cycle was the abrasion between the sleeves and bushings. Insufficient abrasive resistance of sleeves and improper hardness ratio between sleeves and bushings led to rapid abrasion of sleeves. When the sleeves were manufactured by higher hardness materials, the online life cycle was increased from less than 15days to about 20days.

A Method For Producing Hollow Shafts By Rotary Compression Using A Specially Designed Forging Machine

Abstract The paper presents a new method for manufacturing hollow shafts, where tubes are used as billet. First, the design of a specially designed forging machine for rotary compression is described. The machine is then numerically tested with regard to its strength, and the effect of elastic strains of the roll system on the quality of produced parts is determined. The machine’s strength is calculated by the finite element method using the NX Nastran program. Technological capabilities of the machine are determined, too. Next, the results of the modeling of the rotary compression process for a hollow stepped shafts by the finite element method are given. The process for manufacturing hollow shafts was modeled using the Simufact.Forming simulation program. The FEM results are then verified experimentally in the designed forging machine for rotary compression. The experimental results confirm that axisymmetric hollow shafts can be produced by the rotary compression method. It is also confirmed that numerical methods are suitable for investigating both machine design and metal forming processes.

The stribeck curve in cold flat rolling

Cold flat rolling of lubricated steel strips was studied. The three-component system of rolling - the mill, the rolled strip and their interface - was analyzed using a two-step mathematical model, a 1D model and flat rolling experiments. The utilized experimental data have been taken from McConnell and Lenard [1]. The objective of the study was the examination of the interactions of the three components and the development of the Stribeck curve. In the first part of the work, a two-dimensional finite element model was used in which the elastic deformation of the work roll and the elastic–plastic deformation of the strip were considered. Special attention was paid to the events at the lubricated interface where an upgraded version of Levanov’s model was utilized. The model was developed to analyze the local variables at the roll-strip interface. The parameters of the model were determined in an iterative manner, minimizing the differences of the measured and computed roll force and torque. Thus, the relative velocity between the roll and the strip, the roll pressure, the interfacial shear stress and the temperature were obtained. The effect of the temperature on the material parameters of the constitutive equations was also taken into account. Another model was then employed to consider the effects of the local variables on the lubricant’s viscosity. These were then used to obtain the local values of the Sommerfeld number, which in turn led to its average value and to the traditional shape of the Stribeck curve. Further, a simple 1D model of the flat rolling process was also tested for its ability to lead to the Stribeck curve. It was concluded that while both advanced and simple models allowed the development of the curve, removing the simplifying assumptions yielded a more reliable plot.

Evaluating Strip Tillage and Rowcover Use in Organic and Conventional Muskmelon Production

Increasing interest in using cover crops and reduced tillage to build soil health has created a demand for strategies to implement rolled cover crop systems. In northern areas of the United States, cool soil temperature in rolled cover crop systems can create a challenge when growing warm season vegetable crops. The use of rowcovers could mitigate the issue and facilitate adoption of rolled cover crop systems for both conventional and organic growers. This study investigated muskmelon (Cucumis melo) in two production systems, strip tillage (ST) into rolled cereal rye (Secale cereale) or conventional tillage with black plastic mulch (plasticulture), with or without the use of spunbonded polypropylene rowcovers. The trial was conducted in two fields, one in organic management and the other in conventional management. In general, ST led to cooler, moister soils than plasticulture, but rowcovers rarely affected soil temperature. Rowcovers increased mean and maximum daily air temperature by up to 4.2 and 11.7 °C, respectively, and decreased average daily light intensity by 33% to 37%. Rowcovers sometimes increased fruit size, but rarely affected marketable yield. Overall, ST reduced marketable yield compared with plasticulture by 6732 to 9900 lb/acre; however, ST with rowcovers often produced similar vegetative growth compared with plasticulture without rowcovers. Given the slow vining growth habit of muskmelon and the late planting inherent in a rolled cereal rye system, achieving high muskmelon yields, especially early yields, may be difficult.