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An introduction to the hot rolling mill layouts, different mills, machine components and auxiliary equipment

Based on the system approach and on the experience accumulated at theoretical data, design and industrial development of bar rolling, the Chair “Metal Forming” of Ural Federal University develops the universal “Concept of optimum calibration”. The general ideology of roll pass design optimization is stated in article “The concept of optimal bar roll pass design. Report 1. Basic statements”. In the article “The concept of optimal bar roll pass design. Report 2. Calibers space” the structure, appointment and maintenance of the information block reflecting so-called “calibers space” are considered. According to the general concept of optimization, the following task that needs to be solved is the problem of creation of information block so-called “space of schemes of roll pass design” which will be used further as the first space of optimization. The concept “space of schemes of roll pass design of a bar-rolling mill” is considered as the space containing all possible virtual schemes of rolling of a concrete profile on the concrete rolling mill. For formation of the space of schemes of rail calibrations it is necessary to generate separate virtual schemes and to consistently fill this space with them. Thus, the space of calibrations schemes is formed of separate unique calibrations schemes. For formation of this space from separate calibers, it is offered to use the specialized algorithms which are “generators of schemes of roll pass design”. As an example, the structure of the generator prepared for creation of such space for rolling of railway rails is considered. It is revealed that all known rail calibrations can be presented in the form of essentially the same block structure which is used as the central element of the schemes generator of rail calibrations. Usage of described and similar generators in relation to rolling process of a concrete profile on the concrete rolling mill allows obtaining spaces of acceptable schemes of calibrations. Such spaces are necessary for the subsequent optimizing procedures for search of the best calibration scheme from all possible calibrations. The considered approach for creation of calibrations schemes space can be used during creation of computer-aided engineering systems and optimization of calibrations of rolling rolls.

The analysis of two roll pass design options of ten roughing stands atOJSC “MMK” 370 rolling mill has been performed. The usage of a new form of the roll grooves will allow achieving higher durability of the rolls. Lesser rolls consumption will allow saving up to 800K rubles annually. More uniform load distribution by the stands will reduce the possibility of main mill lines equipment breakdowns due to the jumps of rolling torque in the most loaded non-equiaxial stands. Better contact conditions and higher billet stability at the input into equiaxial grooves will reduce the amount of metal clogging. Moreover, a changed strain diagram – with higher roll pass design efficiency factor – will increase the roll out of foundry production defects.

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. Refereed/Peer-reviewed

Since the reserves of the direction of increasing partial pressing and reducing cycles are substantially exhausted, an example of a technical solution for improving the screw piercing based on minimizing partial pres­sing with the increase of cycles of partial pressing, i.e. piercing of profiling billets with a wavy profile is given. The advantages of this technology consist in the reduction of the deformation level in the axial zone of the billet and the decrease of the probability of occurrence of axial destruction. The most effective way of obtaining profiling billets is application of the profile on a three-roll roughing mill of the pipe-rolling plant. To obtain a wavy profile on the surface of the billet, a special roll pass design of three-roll roughing mill is required. Three rolls of the proposed calibration form a caliber, consisting of the input section which provides a secure grip on the billet, the work section with profiling ridges which provides application of the wave profile and the output section. The profiling process can proceed only in case of the equality of the length of the profile period and the billet’s step delivery at the exit of the roughing mill. It is also necessary to consider the ratio of the length profile period to the ridge height, since metal laps can be formed on the surface of the pipe liner after piercing with a low value of the ratio, and at high value of the ratio efficiency of profiling drastically decreases. The ridges on the work section of the rolls are shifted in the rolling direction by the value which is a multiple to the number of rolls, that is for a three-roll mill the shift is 1/3 of the period length of the profile. According to the results of the roll pass design, computer simulation of profiling billets on the roughing mill Q-FORM with positive results was conducted.

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.

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.

In this work, a rolling schedule has been developed, which allows the scrapped S60 railway rail to be used for further processing into semi-finished or finished products. The main purpose of the investigations was to develop the shape and dimensions the rolling grooves and to select the strains in various passes in the ploughshare rolling process. The main problem during roll pass design was the ploughshare shape which is asymmetric and has a varying thickness along the width. The developed roll pass design consist of five passes: one open shape pass, one edging pass and three closed shape passes. The first open shape pass is characterized by an unusual shape which tends to reduce the band asymmetricality in the horizontal axis in such a manner as to prevent the formation of lapping in the sharp corner areas resulting from cutting. Based on the numerical modelling it has been found that the developed roll pass design allows the production of a ploughshare of dimensions conforming to the dimensional assumptions. For the numerical modelling of the rolling process, the Forge2008® computer program was employed.

A new technique is developed to analyze the roll pass design of a section rolling mill. Metal forming nonuniformity and efficiency coefficients, which determine the degree of working of a metal microstructure in rolling of section bars, are used as performance criteria. The system of roll passes intended for the production of a round bar 28 mm in diameter is used as an example to analyze possible deformation schemes and the advantages and disadvantages of each scheme.

Hot steel rolling is amongst the most important industrial techniques because of huge amount of consumed resources, immense environmental impact, and the significance and enormous quantity of long products. Criteria for improving rolling operations include process efficiency, resource consumption, system reliability, product quality and ergo-ecological sustainability. There is an increasing availability of information within and beyond the domain of forming by rolling. With advances in computerised information processing, it becomes apparent that further progress is to be sought in intelligently combining the strategies and theories developed in differing disciplines. The key to optimising rolling systems is to be found in hybrid models. This approach calls for utilising cross-disciplinary knowledge, including a selection amongst methods such as stochastic, fuzzy and genetic modelling, process control and optimisation as well as supply chain and maintenance management. Evidence obtained by experiments using small-scale chemo-physical modelling encourages the use laboratory rolling for preliminary validations. Research strategy is conceptualised on the basis of a knowledge-based hybrid model. The sample space for this model is constituted by the rolling passes translated into the form of vectors. An example of a rolling pass translation into the vector form is presented. Refereed/Peer-reviewed

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.

In this paper, we present an analytic approach for the prediction of roll force to be applicable to the billet rolling process which consists of a series of horizontal stands and vertical stands. The approach is based on the deformation shape and employs the assumption that the deformation homogeneously occurs in three directions. Strain and strain rate are calculated by the geometric relationships between those components and the prescribed deformation functions. By integrating the stress components along the rolling direction, roll force is finally obtained. The prediction accuracy of the proposed model is examined through comparison experimentally mesured roll force with computed ones.

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. Refereed/Peer-reviewed

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.

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 ...

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.

Rolling is today one of the most important industrial processes because a greater volume of material is worked by rolling than by any other technique. Roll wear is a multiplex process where mechanical and thermal fatigue combines with impact, abrasion, adhesion and corrosion, which all depend on system interactions rather than material characteristics only. The situation is more complicated in section rolling because of the intricacy of roll geometry. Wear variables and modes are reviewed along with published methods and models used in the study and testing of roll wear. This paper reviews key aspects of roll wear control — roll material properties, roll pass design, and system factors such as temperature, loads and sliding velocity. An overview of roll materials is given including adamites, high Cr materials, high speed tool steels and compound rolls. Non-uniform wear, recognised as the most detrimental phenomenon in section rolling, can be controlled by roll pass design. This can be achieved by computer-aided graphical and statistical analyses of various pass series. Preliminary results obtained from pilot tests conducted using a two-disc hot wear rig and a scratch tester are discussed.

This paper introduced the rolling process and pass design program of the fitness device tube with unequal fillet with the weld in the corner, and expounded the principle of roll pass design; and applied computer-aided pass design to calculate each sortie pass size of the fitness device tube with unequal fillet, and to optimizate pass. The size and shape tolerances of produced fitness device tube, are all meeting national standards and user requirements.

In the paper a general computer approach strategy concerning the roll pass design for round bars is presented. It deals with roughing and finishing sequences optimizing the pass geometry. The results of the calculation, applied to steel bars, show a good agreement with the geometrical data found in the technical literature or pertaining to existing rolling sequences. In the figures (captions at the end), some partial aspects of the sequences are shown. The user friendly aspects of the program can be recommended to help in solving such type of problems.

Based on the modeling results of the processes of high-quality rolling in calibers of a simple form, the flow patterns of surface layers of the blanks and their influence on the formation of stress-strain state of the metal in the rolling process have been determined and confirmed experimentally. Subject to the formed recommendations a new calibration of rolls of roughing mill of continuous light-section mill 250-2 of OJSC «EVRAZ ZSMK» has been developed and passed the trial approbation. Its use has increased the yield in the production of high-quality rolled structural steel by 3 %. The evaluation to improve the production efficiency by increasing productivity in the implementation process of rolling-separation under the existing continuous light-section mill 250-1 of OJSC «EVRAZ ZSMK» has been conducted. A technique for determining the multiplicity of separation depending on the desired performance increments has been offered, as well as provided the guidance on the calculation of the speed limit in the roughing and finishing stand continuous mill, the actual data on the change of the total reduction ratio and speed conditions on groups stands in the preparation of rebars no. 10, no. 12, no. 14.

In making balls for ball mils the metal is deformed in rolling balls in rolls with helical pass grooves. Insofar as the character of the deformation is concerned, the pass can be divided into the forming section, where the rolls bite the billet and reduce it gradually into the ball shape, and the finishing section where the ball is rolled to the final size and severed from the rest of the billet. A normal process of rolling is provided for by designing the forming section of the pass groove. In the article outcomes calculation roll pass design for rolling of balls. Calculation is made for roiling of ball of125 mm. Initial data for ball-rolling mill design are given.

During the rolling of balls on ball-rolling mill deformation of the metal is in the rolls with screw gauges. In view of such a character of the rolling of deformation is concerned, and can be divided into the forming section, where the rolls bite the billet and reduce it gradually into the ball shape, and the finishing section, where the ball is rolled to the final size and severed from the rest of the billet. A normal process of rolling is provided for by designing the forming section of the pass groove. In the article outcomes the calculation of roll pass designed for rolling of balls. The calculation outcomes for roiling of balls 125 mm. The article provides the initial data for roll pass design of a ball mill.

Defects are often present in rolled products, such as wire rod. The markets demand for wire rod without any defects has increased. In the final wire rod products, defects originating from the steel making, casting, pre-rolling of billets and during the wire rod rolling can appear. In this work, artificial V-shaped longitudinal surface cracks has been analysed experimentally and by means of FEM. The results indicate that the experiments and FEM calculations show the same tendency except in two cases, where instability due to a fairly “round” false round bars disturbed the experiment. FE studies in combination with practical experiments are necessary in order to understand the behaviour of the material flows in the groove and to explain whether the crack will open up as a V-shape or if it will be closed as an I-shape.

The task of designing and optimizing roll pass sequence for rolling of rods and structural profiles remains an uncertain and costly process. Two computer programs were developed for assisting the roll pass design for rolling of (1) rods and (2) structural profiles. The paper describes the approach, the programs and the limited verification of the programs with the available measurements.

In modern rolling mills for special steel the degree of mechanization has greatly increased. Mechanized roughing with both heavy and light billets has been introduced, and flats as well as bars are continuously rolled. When rolling wire in a contiloop mill the tension on the bar between the rolling stands is avoided by loop regulation in a 180° repeater. In new designs the roll diameter has been reduced, allowing rolling of different qualities in the same roll pass design. By means of the installation of several exits from the mills and mechanical equipment for quick changing, use of the mills is increased. Special steel is rolled as 5·5-8 mm dia. wire at a speed of 35 m/s. A production capacity of over 11000 t/month for the rolling of special steel in the range 5·5-26 mm dia. has been achieved. There are new rolling units for rolling at 50 m/s in order to increase the production when rolling the smallest dimensions. A new patenting method, the ED (easy drawing) process, with coiling directly into...