Intermediate Roll Research Articles

Contact Element Method with Two Relative Coordinates and Its Application to Prediction of Strip Profile of a Sendzimir Mill

A new numerical method, Contact Element Method with Two Relative Coordinates, has been developed. The main features of this method are that element meshing depends on the contact length between rolls or between the work roll and the strip, and that each element has two relative coordinates based on two separate contact objects. With this method, a program code “Setup Models for Sendzimir Mill” (SM4SM) has been developed for prediction of the strip profile of a 20-high Sendzimir mill with double AS-U-Roll systems. The strip profiles are predicted under various rolling conditions, such as the positions of AS-U racks, the 1st intermediate roll (IMR) shift and taper slope & length, the roll J profile and the coefficient of friction, etc.

可撓性に優れたバックアップロールとコンケーブ状プロフィールを付与した第1中間ロールによる形状制御

Flexible shaft backing assemblies (FSBAs) have been introduced into an actual 20-high Sendzimir mill and shape control technology using FSBAs has been investigated. In our previous paper, it was found that the shape control range was extended by the introduction of FSBAs, mainly toward the quarter buckles side and edge waves side. Thus, shape control technology with the combination of FSBAs and the first intermediate rolls given a concave profile partially (concave rolls) was investigated to improve quarter buckles. From simulations carried out using the analysis model which was described in the previous paper, it was found that quarter buckles were improved by optimizing the concave roll profile. In experiments using rolls with the concave profile in the 20-high Sendzimir mill, it was confirmed that quarter buckles were improved under extensive rolling conditions. It was also confirmed that better strip shape was obtained by combining FSBAs and concave rolls than using only concave rolls. FSBAs and concave rolls have been applied to commercial production and have contributed to the improvement of strip shape.

Model-based evaluation of the effect of horizontal roll offset on cross-directional control performance in cold-strip rolling

Some modern rolling mills allow for the work and intermediate rolls to be offset in the plane of the strip, allowing three-dimensional roll deformation. A generalised extension to existing roll-stack models is proposed in order to characterise this effect. The model is used to explore the influence of three-dimensional roll deformation on the prediction of actuator sensitivities used in cross-directional control systems in cold rolling. It is shown that horizontal work-roll offset alters the magnitude and form of all existing actuator responses. The effect is dependent on the degree of offset and on the work-roll diameter and is most pronounced in the parabolic component of bulk actuators. Further, the horizontal roll offset can itself be used as an actuator, although the magnitude of its sensitivity varies significantly with the degree of offset.

Row and column generation technique for a multistage cutting stock problem

The multistage cutting stock problem (CSP) generalizes the one-dimensional CSP when a lengthwise cutting process is distributed over two or more successive stages. At every stage of the cutting process incoming rolls are slit into smaller rolls by width. The problem is to minimize total trim loss occurring at all stages of technological process meeting customer demands for finished rolls. We propose a row and column generation technique for solving the multistage one-dimensional CSP. The technique is a generalization of the column generation method suggested by Gilmore and Gomory for solving a classic CSP. The procedure generates only those intermediate rolls (rows) and cutting patterns (columns) that are needed. An auxiliary problem embedded into the frame of the revised simplex algorithm is a non-linear knapsack problem that can be solved efficiently. Computational results prove the overall method is a valuable addition to the tool set for modeling and solving the multistage CSP. Scope and purpose We investigate a broad class of large-scale linear programming models and suggest a new and efficient way to solve them. The proposed method belongs to a category of decomposition techniques generalizing the famous column generation method. An iteration of the revised simplex algorithm may “enrich” the LP matrix either by generating a new column, as a purely column generation method does, or by generating a combination of a new row and a pair of new columns. The method is a row and column generation technique that we propose and investigate. Applications modeled by a multistage CSP occur in the industries that use a multistage cutting process: paper, leather, film, steel, etc., or a nested packing/loading process: transportation. The unknown variables in the multistage cutting stock problem are intermediate sizes (rows) and cutting patterns (columns). According to the algorithm both are to be generated dynamically. The proposed algorithm brings tremendous benefits in terms of the quality of solutions and computational performance.

Improvement of the work roll performance on the 2050 mm hot strip mill at Iscor Vanderbijlpark

This paper describes how an optimization of the rolling conditions (roll lubrication, strip chilling) and the use of new roll qualities on the 2050 mm hot strip mill at Iscor Vanderbijlpark, allowed to realize the full potential of HSS rolls. Based on development work and laboratory studies on oxidation behaviour, these improvements benefit both to Hi-Cr and HSS rolls. The full implementation of HSS in stands F1 to F4 during year 2000 will allow to increase the mill availability by eliminating the intermediate roll change and reduce the work load in the roll shop.

Automation for Shape Control in Stainless Cold Rolling Mill

The shape of cold strip for the stainless process has been become issue in quality recently, and hence POSCO developed an automatic control system for strip shape in the sendzimir mill. The strip shape is controlled by As_U roll and first intermediate roll. A shape control system is applied to real plant. The actual shape is recognized by neural network and the fuzzy controller controls positions of actuators. The experiments are made on line and the control performance shows very efficient for the profile tracking, shape symmetry and fluctuation of shape.

On-Line Multinip Calender

The direction in calendering is towards on-line solutions, even with such higher value-added printingpapers as SC-grades and glossy coated papers.Soft calendering has enhanced the finishing of several grades, enabling quality which is better than with conventional machine calendering in hard nips, while at the same time simlifying the process by reducing the number of nips needed and employing simpler web runs. Still, there are limitations to soft calendering. Smoothness improvement is limited by relatively low nip pressures due to the wider nips associated with the large-diameter rolls used, and by the limited number of nips. On the other hand, off line supercalenders have continued to produce the highest quality capability. The biggest drawbacks to conventional supercalendering are the relatively slow speed, off-line operation and dependence on the use of filled rolls. These factors limit the production capacity and prevent supercalenders from meeting the challenge presented by faster paper machines.While advances in hot soft calendering and supercalendering have improved the state of calendering technology, there is a clear need for a new approach to calendering to produce SC-type grade, coated printing papers and similar value-added grades. That approach is OptiLoad.OptiLoad incorporates many innovative developments, such as Dura polymer-cover soft rolls and heated intermediate rolls. The top and bottom rolls are softcovered, zone-controlled Sym-Z rolls or multizone Sym CD rolls for effective caliper profiling. The OptiLoad principle makes it possible to fully relieve the total weight of each intermediate roll, utilizing lever arms and hydraulic relieving cylinders. Till now 18 off-line and 6 on-line OptiLoads including near future start-ups have already been sold in the world.

The influence of intermediate roll characteristics on the residual crack density and critical current density in multifilamentary (Bi, Pb)2Sr2Ca2Cu3Ox tapes

We studied the influence of the intermediate rolling deformation on the residual crack network and critical current density in multifilamentary (Bi,Pb)2Sr2Ca2Cu3Ox (2223) tapes. Although an intermediate rolling step between heat treatment is generally beneficial in raising the critical current density, it also has the negative effect of causing cracking. Cracking was evaluated both by magneto optical imaging and by ultrasonic fracture of extracted filaments. We found that the characteristic fragment size was sensitive to both roll diameter and reduction percentage, decreasing from ~210 µm for a 10% reduction to ~115 µm for a ~20% reduction with 152 mm diameter rolls. At a constant 10% reduction, the fragment size decreased from ~210 µm to ~140 µm when changing from 152 mm to 38 mm diameter rolls. We conclude that intermediate deformation is positive in so far as it decreases the filament porosity, but that it cannot reduce this too much without introducing more cracking than can be healed in subsequent heat treatment. The critical current density thus maximizes at an intermediate deformation that counterbalances these two oppositely directed influences on the filament connectivity.

A knowledge-based expert system for roll pass and profile design for shape rolling of round and square bars

Abstract In shape rolling, the determination of roll pass and profile design is of importance. In the present investigation, a knowledge-based expert system is developed for the design of roll pass and profile sequences for the shape rolling of round and square bars. For development of the program, C++ language and an object oriented programming technique were utilized in consideration of the flexibility and expandability of the program. A backward chaining algorithm was employed for the inference engine to determine the manufacturing sequences in reverse order based on design rules extracted from the literature. For optimization of the process sequence design, the number of roll passes was minimized by comparing the error between the inferred roll passes and the initial error provided as input. In the currently developed expert system, five geometries such as box, square, diamond, oval and round were introduced as a basic geometry to describe the intermediate roll geometries. In addition, the roll separating force, area reduction and change of length at each stage of shape rolling were determined and displayed on the monitor of a personal computer. The system was applied for the shape rolling of round and square bars. The process sequences determined were proven to be reasonable compared to those available at practice.

Simulation of fuzzy shape control for cold-rolled strip with randomly irregular strip shape

Control of cross-sectional cold rolled strip shapes is an important subject in rolling mill because of improvement of cold-rolled strip qualities. However, it is not easy to tackle the problem in a mathematical form since the cold rolling process is a highly nonlinear system in which many parameter are involved. In this study, a fuzzy control algorithm was developed to control the randomly irregular cold-rolled strip. The currently developed fuzzy control algorithm consists of two parts: the first part calculates the changes of work and intermediate rolls bender forces based on the symmetric part of the irregular cold rolled strip shape, and the second part calculates the weighting factors based on the asymmetric part in order to modify the pre-determined roll bender forces. As a result of this, tender forces applied at both sides of the cold-rolled strip will be different. The fuzzy rules were formulated based on the production data to control the delivery shape at the last stand of a tandem cold mill. In order to simulate continuous shape control, the fuzzy controller was linked with an emulator. The emulator was constructed by neural network theory based on the same production data. According to calculated bender forces of work and intermediate rolls from the developed fuzzy controller, the emulator predicted the changes of the randomly irregular cold rolled strip shape. The developed fuzzy controller and emulator simulated the cold rolling process until the randomly irregular shape converged to a tolerable range to produce a uniform cross-sectional strip shape. The simulations were carried out on IBM PC 486. The results obtained from the simulations were reasonable for various randomly irregular strip shapes. Thus, the developed fuzzy control system might be useful in controlling the cold rolling process without introducing manual control.

Automatically Roll Storage System and Track Loading System

For the intermediate roll warehouse that is installed at the first of finishing process in paper mill, full automatic roll storage warehouse using “automatic control crane and vacuum lifter” is generally being prepared in the world, recently. The vacuum lifters of 58 quantity are already being used in the world according to our data which we caught at present. As one vacuum lifter is almost always used with one crane generally, I think automatic roll storage warehouses of about 50 systems are being used in the world. In such situation, we have received new orders of 21 systems from each paper making companies of Indonesia, China, Korea and Chile. The system like this was almost used in central Europe like Germany so far, however nowadays this system is the story which it is acknowledged in the world and expanding into the world. In this paper it is shown for the merit of this system, example in use and summary of 21 systems.Next, in this paper it is also shown regarding to make automatically loading and unloading rolls and skid papers for track. They are being loaded and unloaded by using lift track in paper mill and warehouse in Japan. Therefore there are such many problems as that the track must stop during long time and rolls have a lot of wound at the roll surface and transformation, but we properly accept the problems. However in Europe as track loading systems solved their problems are being used, I introduce the merit of this system and the example in use for the system.They are written by most newest information in the world, then I believe you can receive some benefit from this paper for you.

Shape control of alloy steel rolled by sendzimir mill

In order to improve quarter waves occurred in the wide and thin gauged alloy steel rolled by 20-high sendzimir mill, a computer simulation based on the divided element method and an actual cold rolling experiment were carried out. Quarter waves were simulated by elastic deformation analysis of rolls considering bending deformation of back up rolls and the effect of control actuators on controllability of quarter waves were analyzed. Computer simulation showed that control actuators such as shifting of the 1st intermediate roll and crown adjustment of As-U-Roll in back up rolls were not effective to control quarter waves and that changing taper mode (both length and magnitude) at the barrel-end taper radius of the 1st intermediate roll was rather very effective. From an actual rolling experiment it was verified that quarter waves could be reduced remarkerably by changing taper mode of the 1st intermediate roll.

Simulation of Fuzzy Shape Control for Cold-Rolled Strip with Randomly Irregular Strip Shape

In this study, a fuzzy control algorithm was developed for the randomly irregular shape of cold-rolled strip. Currently developed fuzzy control algorithm consists of two parts: the first part calculates the changes of work and intermediate roll bender forces based on the symmetric part of the irregular strip shape, and the second part calculates the weighting factors based on the asymmetric part and modifies the pre-determined roll bender forces according to the weighting factors. As a result of this, bender froces applied at the both sides of the cold-rolled strip were different. In order to simulate the continuous shape control. fuzzy controller developed was linked with emulator which was developed based on neural network. The fuzzy controller and emulator developed simulated the cold rolling process until irregular shape converged to a tolerable range in producing uniform cross-sectional strip shape. The results obtained from the simulation were reasonable for various irregular strip shapes.

An LP-based approach to a two-stage cutting stock problem

This paper describes a linear programming model for a two-stage cutting stock problem that arises in a make-to-order steel company. For technological reasons, there are two different cutting operations. Between the cutting operations, the intermediate rolls are processed to obtain the required characteristics. The minimization of the trim loss and the reduction of the number of set-ups are primary concerns in cutting stock problems. In this case, it is also important to minimize the number of intermediate rolls, in order to reduce the processing work. These objectives may be conflicting and a balance may be necessary. We present a simplified LP model, which is solved by a column generation technique. The subproblems are relatively large knapsack problems. Computational results for a microcomputer are presented.

Development of fuzzy control algorithm for shape control in cold rolling

In this study, fuzzy theory is introduced in controlling the strip shape in cold rolling. Fuzzy control algorithm is developed based on the production data and operational knowledge. The cold-rolled products are characterized into several types based on its irregularity, ‘edge wave’, ‘center buckle’, ‘W-type’, and ‘M-type’. The developed fuzzy controller calculates for each type of irregular strip shape, the change of bender forces of work and intermediate rolls, using fuzzy rules and fuzzy inference. To simulate the continuous shape control, the fuzzy controller is combined with the emulator which is developed using neural network. The developed fuzzy controller and emulator simulate the cold rolling process until the irregularities converge to the tolerable range to produce a uniform cross-sectional shape. The results from the various simulations demonstrate that the developed fuzzy control algorithm works for various types of irregular cross-sectional shapes as well as simple shapes.

A Computer Based Interactive Approach To A Two-Stage Cutting Stock Problem

AbstractIn this article, we present a computer interactive system, developed for a Portuguese steel manufacturer operating at the retail level. The production process includes not only cutting operations, which are performed in two different stages, but also intermediate processing.Minimization of trim loss and reduction of set-up are primary objective in every cutting stock problem. In this system, there is also another important objective, which is the minimization of the number of intermediate rolls. Because these objectives may be conflicting, a balance between them may be necessary. Another feature of the system is that the weight of the raw material rolls may vary slightly.New models were built and integrated in an interactive computer system, developed for a microcomputer. In each planning period, the system is used to establish a couple of dozens of operational cutting plans, one for each different raw material. The results obtained are slightly better than the previously obtained by experienced s...

バキュームロールリフターによるロール自動倉庫

In Europe, particularly in Germany, there has been a rising tendency in recent years for paper mills to adopt automatic warehouse systems (which utilize vacuum roll lifters) as an intermediate roll storage facility at the first stage of the finishing process.The automatic warehouse system utilizing vacuum roll lifters is composed of : 1. A vacuum roll lifter2. A crane plus a crane controller3. Conveyor systems for roll feeding and discharge4. A computer system for storage control5. A building and incidental equipmentVacuum roll lifters, so designed as to lift rolls upright by applying suction on the roll ends with vacuum force, have such features as follows : 1. Substantial space economy is attainable because rolls are placed upright on the warehouse floor.2. Larger diameter rolls can be handled without damage.Because of these superior features, construction and management of an economical warehouse system can be attained with the vacuum roll lifters.

Shape Controllability for Quarter Buckles of Strip in 20-high Sendzimir Mills.

A simulation model for predicting the shapes of cold-rolled strips in 20-high Sendzimir mills was developed, and its predicting accuracy was assessed experimentally. By this model, improvement of quarter buckles was shown difficult merely by conventional shape control actuators, i.e., lateral shifts and taper profiles of first intermediate rolls, roll crowns of work rolls and second intermediate rolls, and crown adjustment of back-up rolls. It was shown that quarter buckles could be effectively corrected by giving a concave profile partially to the first intermediate rolls.

Prediction of Flatness of Fine Gauge Strip Rolled by 12-high Cluster Mill.

A mathematical model for predicting flatness of fine gauge strip after rolling is established. The model is able to obtain the soultion for the roll-kiss rolling by way of matrix computation, and it is designed to analyze any type of strip rolling mill. Flatness control capability of a 12-high cluster mill during the roll-kiss rolling is investigated using the present model. The investigation reaches the following conclusions. (1) The effect of work roll bending force on strip flatness is extremely small. (2) Intermediate roll shift is effective when tapered portion is shifted into the material width. However, without taper the effect of intermediate roll shift on the strip flatness is marginal. (3) Both back-up roll crown adjust and intermediate roll bending force are effective for flatness control.

Shape control in Sendzimir mills using both crown and intermediate roll actuators

A control philosophy utilizing both the As-U-Rolls and first intermediate rolls as shape control mechanisms is described. A robustness result for the design is developed. The result is useful, because such a mill is normally used to roll a large number of materials, and a single controller must therefore be used for many different schedules. A variety of simulation results are presented, showing the transient responses and performance of the multivariable shape control system.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>