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The paper presents a modification of the slitting pass system for the three-strand rolling of 16 mm-diameter ribbed bars, which will reduce the wear of rolls, and thus increase the economic efficiency of the analysed process. The results of theoretical research were verified on the basis of the performed measurements of force and energy parameters during the rolling of ribbed bars according to the multi-strand technology in a D350 continuous rolling mill. The computer program Forge2011® was used for theoretical analysis of the rolling process with longitudinal strand separation.

This study considers roll pass design from the standpoint of system-level analysis within the UrFU concept of optimal roll pass design developed at the Department of Metal Forming of the Ural Federal University. Roll pass design as a process system is changed by two methods, that is, either by changing the structure of the system, which corresponds to changes in the groove shape, or by changing the control of the system, which corresponds to changing reductions by passes in one and the same grooves, that is, by changing reduction mode. The roll pass design that is considered optimal contains such grooves and uses such reduction mode, at which the extreme properties of preset target functions are ensured depending on the indicated parameters. In previous reports, the general concept of the two-stage optimization of roll pass design is considered. This concept implies a consistent optimization of the roll pass design scheme (optimization stage one) and reduction mode (optimization stage two). In addition, procedures of shaping the optimization space for stage one are considered. This space includes virtual roll pass design schemes and is shaped by the special generator of these schemes and the set of all possible types of grooves that can be used at this particular stage of rolling. To calculate the target function of the optimality criterion of the roll pass design scheme, the groove efficiency space concept is introduced. This space is shaped by the formalized expert assessment of the degree of influence of various permissible forms of grooves used in roll pass design on the diverse technological, economic and other characteristics of a particular rolling mill. The target function is calculated as variance of integral performance indicators of the grooves included in the roll pass design relative to the hypothetical ideal groove with the best values of selected performance indicators. The roll pass design scheme corresponding to the minimal target function is considered the best. [ABSTRACT FROM AUTHOR]

The paper presents a modification of the slitting pass system for the three-strand rolling of 16 mm-diameter ribbed bars, which will reduce the wear of rolls, and thus increase the economic efficiency of the analysed process. The results of theoretical research were verified on the basis of the performed measurements of force and energy parameters during the rolling of ribbed bars according to the multi-strand technology in a D350 continuous rolling mill. The computer program Forge2011® was used for theoretical analysis of the rolling process with longitudinal strand separation. [ABSTRACT FROM AUTHOR]

The application of finite element simulation to the problem of roll pass design for round bar rolling is considered. Two roll pass sequences were developed by analytical methods and then optimized using 2.5D Finite Element Method (FEM). The first one is a classical oval-round roll pass design. The second one is a combination of flat rolls and round roll passes. Relying on the simulation data obtained by FEM, the roll gaps were adjusted to achieve the required bar shape and the uniform distribution of rolling force between the passes. Advantages and disadvantages of each roll pass design were considered.

Hot rolling is among the most widely used manufacturing techniques. However, rolling mills are major resource consumers; thus, urgent rationalisation is required in the relevant industrial systems. Roll pass design (RPD) is a principal factor that determines process efficiency, product quality and resource consumption. Therefore, it is important to optimise RPD including the selection of roll materials. New avenues for optimising RPD are to be found by extracting knowledge buried in the vast repository of industrial records. The extracted statistical functions are then used for the non-linear optimisation of RPD parameters. The design of a leading oval groove for rolling a wire rod is presented as an example, along with a discussion of the general mathematical aspects. The presented case analysis shows how regression analysis and the probability density function (PDF) are used to define principal dimensions-height and width-for the leading oval groove. These two dimensions are inferred following the logic of probabilistic design, and are based on an understanding of the trend in groove contour changes, which occur due to surface wear during rolling campaigns. [ABSTRACT FROM AUTHOR]

The quality of springs depends on the rod surface. Requirements to the surface quality and depth of decarbonized layer of hot rolled coils are becoming stricter. Allowable depth of partial/complete decarbonization layer is 0,14/0,03 mm. The most common methods for preventing growth of decarbonized layer is controlled steel heating and metal forming control. Using controlled heating we can not always ensure that the depth of the decarbonization layer is not exceeded. The aim of the study is to control the uniformity of deformation to reduce the thickness of the decarbonized layer. This article focuses on roll pass design optimization (the width, height and angle of fillet) for intermediate stands and for finishing high-speed stands block (Danieli "BGV"). During experimental rolling in the new way of deformation in a volume of more than 50 tons, there was no sticking of metal in the stands, and final sizes of rolled round product with 14 mm diameter were within the existing tolerances for products (±0.3 mm). The result of using a new roll pass design configuration was the production of rolled products with high surface quality; and in the future, we have a possibility to produce automotive coil springs meeting high performance requirements. [ABSTRACT FROM AUTHOR]

The aim of this paper is to critically assess the potential of mathematical modelling which uses finite element method software for solving operation problems in the hot rolling of flat and long products. We focused on concrete issues faced by rolling plants in the Moravian-Silesian region (Czech Republic). The investigation was always combined with field or pilot measurements or laboratory experiments.

Human-computer interface was utilized to amplify the power of a hybrid algorithm that combines fuzzy logic, regression analysis, and non-linear optimization to extract knowledge from a roll pass design database. This strategy is applied to grooves with vertical and horizontal symmetry which are employed in initial passes to roll a broad range of steel products. The results presented here from the case study are both statistically significant and valid from the viewpoint of roll pass design theory. [ABSTRACT FROM AUTHOR]

In this paper, the design method for intermediate rolls has been developed to manufacture a linear motion (LM) guide block in horizontal-vertical (H-V) shape rolling, based on the three-dimensional electric field analysis (3D-EFA). This design method can predict appropriate cross-sections of roll profile at each pass based on the initial and final shapes. 3D-EFA simulations are performed separately for the horizontal and vertical rolling passes to obtain roll profiles from equipotential lines. The roll profiles obtained based on 3D-EFA are simulated by the commercial program Deform 3D, and are the reselected by compensating for the area of the error from the equipotential lines. For convenience of field work and reducing strain concentration of the products, the roll profiles for the first and second passes are modified to be flat rolls because the roll profiles are almost rectangular. The effectiveness of the proposed design method is verified experimentally using AISI4120 steel for H-V shape rolling. From the experimental results, some over- and under-filling ate the roll gap are observed for the final pass. However the dimensional errors are within ±0.3 mm, and no cracking or shearing is observed. The proposed design method will improve the efficiency of the design process by reducing time and costs. [ABSTRACT FROM AUTHOR]

A design method using three-dimensional electric field analysis (3D-EFA) and a backward tracing scheme (BWT) is proposed to improve the dimensional accuracy for a complex shaped product in shape rolling. A complex door hinge used in the door hinge of automobile is taken as a case study. A shape rolling process for this hinge is designed using the proposed method, and a backward tracing scheme is then applied to find a more suitable roll profile. 3D-EFA is carried out for this purpose, and the roll profiles at each pass are selected based on the 3D-EFA results using the reduction ratio in the area per pass. In addition, a BWT is applied to the selected roll profile in order to achieve the dimensions of the required product. The effectiveness of the proposed design method is verified via FE-simulation and experimentation using plasticine. The results of FE-simulation and experiment show that the proposed design method can be used to effectively design the roll profile for the complex door hinge, leading to an accurate shape and correct dimensions of the final within an allowable tolerance of ±0.5 mm. Therefore, it can be concluded that the proposed design method can be widely used to design roll profiles for producing a precise product. [ABSTRACT FROM AUTHOR]

The application of finite element simulation to the problem of roll pass design for round bar rolling is considered. Two roll pass sequences were developed by analytical methods and then optimized using 2.5D Finite Element Method (FEM). The first one is a classical oval-round roll pass design. The second one is a combination of flat rolls and round roll passes. Relying on the simulation data obtained by FEM, the roll gaps were adjusted to achieve the required bar shape and the uniform distribution of rolling force between the passes. Advantages and disadvantages of each roll pass design were considered. [ABSTRACT FROM AUTHOR]

In the shape rolling process, the reduction of the number of passes is a challenging topic for the steel industry. This can be achieved by enhancing the design approach or by developing new rolling passes that allow the production of high cross-section reductions such as with the slit roll pass. However, in order to design a robust roll pass, the lateral spread of the workpiece must be predicted correctly to prevent incomplete, or even worse, excessive roll groove fulfilling (which may cause roll damage). In the present investigation, the possibility of using a finite element model to predict the lateral spread in a slit roll pass is investigated. The results of the finite element model are then used to adapt and calibrate two analytical models that were developed originally for strip rolling and shape rolling with concave grooves. [ABSTRACT FROM AUTHOR]

A new multi-pass hot shape rolling was designed based on a three-dimensional analysis of channel section beams in hot rolling by the finite element method. A complete production line in industry containing 13 passes in forming the section including break-down, intermediate, and finishing sequences is modeled. The output geometry and power consumption predicted by this simulation were verified against the practical data and the measured values of the production line of Zobahan Esfahan Company. Then, a sample caliber design process to achieve a specific cross section is prepared. The minimum possible number of passes consistent with the parameters affecting the spread is the main strategy of the new caliber design. Again this new caliber design is simulated using an explicit finite element code. The geometry and dimensions of the exit cross section, the separation force, roll torques, and the power consumption in each stage are calculated. Comparison of the new roll pass parameters and that of the conventional ones in industry is made to demonstrate the advantages of the new caliber design. [ABSTRACT FROM AUTHOR]

The present work introduces an expert system that automatically selects and designs rolling sequences for the production of square and round wires. The design strategy is aimed at reducing the overall number of passes assuming a series of process constraints, e.g., available roll cage power and torque, rolls groove filling behaviors, etc. The method is carried out into two steps: first a genetic algorithm is used to select the proper rolling sequence allowing to achieve a desired finished product; then, an optimization roll pass design tool is utilized for proper design of roll passes. Indeed, an artificial neural network (ANN) is utilized to predict the main geometrical characteristics of the rolled semi-finished product and technological requirements. The ANN was trained with a non-linear finite element (FE) model. The proposed methodology was applied to some industrial cases to show the validity of the proposed approach in terms of reduction of number of passes and search robustness. [ABSTRACT FROM AUTHOR]

The aim of this paper is to critically assess the potential of mathematical modelling which uses finite element method software for solving operation problems in the hot rolling of flat and long products. We focused on concrete issues faced by rolling plants in the Moravian-Silesian region (Czech Republic). The investigation was always combined with field or pilot measurements or laboratory experiments. [ABSTRACT FROM AUTHOR]

The aim of this work has been to develop an automatic roll pass design method, capable of minimizing the number of roll passes. The adoption of artificial intelligence technologies, particularly expert systems, and a hybrid model for the surface profile evaluation of rolled bars, has allowed us to model the search for the minimal sequence with a tree path search. This approach permitted a geometrical optimization of roll passes while allowing automation of the roll pass design process. Moreover, the heuristic nature of the inferential engine contributes a great deal toward reducing search time, thus allowing such a system to be employed for industrial purposes. Finally, this new approach was compared with other recently developed automatic systems to validate and measure possible improvements among them. [ABSTRACT FROM AUTHOR]

The article discusses a study which examines surface defects in wire rod rolling process. Artificial V-shaped longitudinal surface cracks are analyzed experimentally and numerically using finite element method (FEM). FEM method is a good tool for analyzing crack behavior. However, experimental results always show faster reduction of the cracks than the FEM calculation.

Abstract: In shape rolling process, the definition of roll pass and profile design is important. For the prediction of workpiece sectional shape, for some rod rolling passes, an analytical model by Shinokura and Takai was proposed and verified. The application of FE techniques to the rod rolling process lets to study some other passes with much simplicity. In this paper, for round-flat oval pass and round-flat pass, in rebar rolling, the experimental values of maximum spread and of radius of the rebar have been carried out and compared with the results of the analytical model and of the FEM analysis. The FE model has been developed with MSC.Marc Autoforge program, a FE non-linear solver, dedicated to simulate plastic strain working. [Copyright &y& Elsevier]

Abstract: A calculation procedure has been developed to determine the working range for series of grooves including “oval”, “round”, “false round”, “square” and “diamond” shapes. The minimum and maximum roll-gap setting and corresponding bar areas are calculated for all grooves. Flatter ovals increase the flexibility in false round–oval series and low rolling geometry factors reduce the working range. The working range is smaller for pass sequences designed for high reductions. To evaluate the model, laboratory tests for passes in “round”–“oval”–“false round”–“oval” sequences were carried out. Samples from a square–oval series were examined and it was shown that this series was insufficient for stainless steel wire rod rolling. The fitting factors were too high and the square grooves were slightly overfilled. It is shown that “false round”–“oval” series give the largest working range and thus enable the rolling of a wide range of different stainless steel grades. [Copyright &y& Elsevier]

An analytical approach is presented to investigate the deformation characteristics of billets in a continuous billet mill using power driven horizontal stands and idle vertical stands. The analysis is validated by comparison to the experimental results in a previously published work. The analytical results have shown that, apart from the problems of slip and buckling of billet, there are some shortcomings involved in this method. Compared to conventional rolling with all driven stands, the roll load for idle vertical stands and the rolling torque for horizontal stands are almost doubled. The billet is severely stressed within the roll-bite of idle vertical stands and the overall rolling power has increased by one third of that for conventional rolling. These shortcomings impair the feasibility of industrial application of idle vertical stand rolling method. [ABSTRACT FROM AUTHOR]

In the high speed rolling of wire rod in blocks, interstand tensions are utilised in order to keep the process stable. However, interstand tensions influence the rolling process, and especially the spread and forward slip, which are dependent of tensions between the stands. By the influence on spread, the tolerances of the rolled product depend on the tensions and usually the interstand tensions are kept as low as possible in order to obtain required tolerances. A narrow spread technology is used to utilise interstand tensions in order to increase the working range of a pass sequence and move the product range towards smaller sizes. By adapting a certain amount of interstand tensions, smaller sizes can be rolled by a given roll pass schedule. A practical problem in this method is the fixed gearings in the common blocks, which require a certain and given level of interstand tensions and corresponding reductions. In the latest generation of blocks, where the stands are arranged in units, two by two, with each unit driven by a dedicated electrical motor, it is possible to introduce 'inter unit' tensions, and by this method extend the working range of the pass sequence. A special computer program for analysis of interstand tensions has been developed by combining a program TENSION, developed at the Royal Institute of Technology in Stockholm, dealing with the basic principles of rolling with interstand tensions, with the recently published program WORKRAN, which analyses the working range of any roll pass sequence built up by common two-symmetrical grooves. From the analysis and experimental data it is shown that interstand tensions at the level of 10% of the yield stress of the material increase the working range in a six stand block by 2% and reduce the lower limit of the exit section area by about 15%. Higher tension levels have a larger effect both on the extension of the working range and on the reduction of the minimum exit area but it becomes more difficult to control the tolerances at higher tension levels. The influence of interstand tensions on the reduction and on the working range of the pass sequence is mainly obtained by the influence on the round passes, while the oval passes have a counteracting effect on the influence of interstand tensions. [ABSTRACT FROM AUTHOR]

In this study, a computer-aided-design (CAD) system to support roll pass and roll profile design of bar rolling, where simple shapes like round and square bars are produced, was developed in order to minimize trial and errors in industry. An interactive design methodology was used in the developed system to provide various design examples from which decisions for an optimal design can be made. In addition, an algorithm for generating automatic roll pass design of local passes was proposed. In order to effectively assist the interactive design process, material flow and engineering data such as roll separating force and required power, based on reliable empirical formulas, were calculated and displayed. For more accurate engineering calculations, roll speed was calculated for continuous rolling and an approximate heat transfer model was proposed. Finally, the developed system was applied in the process design for rolling a square bar. It was found that the system will improve the efficiency of designing process by reducing time and cost. [Copyright &y& Elsevier]

In order to achieve a good distribution of reinforcement particles in a cast metal matrix composite (MMC), the stirring action must be efficient enough to disperse the particles in a homogeneous way. In normal practice stirring takes place in a closed vessel or crucible, where efficiency cannot be seen, and simulation methods are required to inform experimental research. For this research finite element analysis, employing a specialised computational fluid dynamics package, is used to simulate the fluid flow, and thus dispersion of reinforcement material in a molten matrix alloy during stirring. The emphasis is on investigating optimum stirring conditions in order to achieve effective flow patterns to disperse the solid particles in the melt, without breaking the surface layer of the melt.The simulation shows that the stirring parameters such as stirring speed, and impeller position in the crucible have a significant effect on the flow behaviour of the fluid. These parameters interact, with various combinations generating suitable conditions for composite mixing. The model was validated using a visualisation experiment which indicates that, despite some limitations arising from the simplification of the physical situation, the model is a useful tool in specifying process parameter in the production of MMCs. [Copyright &y& Elsevier]