proceeding of fourteenth abaqus user group2001p01_W

1、ADVANCED ANALYSIS SYSTEM FOR ROLL PASS DESIGND.C.J.Farrugia a, 1 and D.Jennings ba Corus, Swinden Technology Centre, Moorgate Rd, Rotherham S60 3ARb Corus, Corus Construction and Industrial, Redcar, TeessideTS10 5QLAs the requirements for rolled sections become more complex, with an ever increasing

2、demand for reducing design cycles for new products, Corus (Formerly British Steel), at its Construction and Industrial Division (CC&I), together with Hibbitt, Karlsson & Sorensen (HKS), have as part of a three year project developed an integrated rolling mill simulation system for long products. Run

3、ning on Silicon Graphics Origin 2000 and NT Desktop platforms, the system is being used in the Works environment by roll design engineers to optimise the hot rolling process for a wide range of steel sections.This paper describes some of the key features of this simulation system and the way the sys

4、tem is being used and integrated with the CAD and knowledge based system platform, providing a broad range of advanced analysis capabilities and knowledge encapsulation for the rolling mill engineers. Particular attention is given to the development and use of key features, such as the adaptive reme

5、shing in ABAQUS/Explicit, steady state control, and thermo-mechanical analysis together with the development of a powerful user-friendly interface within ABAQUS/CAE.Future directions in terms of the roll pass design system and technique development are also described with the aid of illustrative exa

6、mples.1. BACKGROUNDRoll design for long products is recognised as a core skill upon which the ability to accelerate new product developments, whilst enhancing quality and consistency of current products, depends 1. Traditionally, roll design has been undertaken by individual experts using a mixture

7、of empirical (semi-) knowledge, sound engineering and rolling practices and theory adapted from flat rolling. Although this process has been successful in optimising current product portfolio and developing new products (mostly from incremental adaption from existing family of products), the knowled

8、ge of roll design is very much confined to key individuals and in many instances no clear or explicit rules to design exist. Roll design can be defined as the ability to design a series of roll pockets and draughting sequences (i.e. number1Corresponding authorP01/1of passes and reduction ratios) wit

9、hin the constraint of the mills (geometric, mechanical, etc.) in order to obtain a cold finished section (shape and properties within tolerance) from an initial feedstock (concast reheated slab/blooms/billets with standard dimensions). Typical sections include beams, columns, channels, angles, rails

10、, piling, etc.The key factor for effective design is the determination of the development of lateral spread (at steady state)/elongation throughout the rolling sequence, and the roll designers will have to consider parameters such as the pocket geometry, roll diameters, material quality and temperat

11、ure, and so on. In the past, rules for design were largely unwritten and therefore knowledge was implicit. These consider limits imposed by mill configuration (roll barrel length, min/max diameter, loads/torque/power, feedstock available, etc.) but also procedural steps such as, the design starts by

12、 considering the final pass (hot finished section), differential elongation has to be minimised, design for spreading is dependent on pass shape, position of roll pockets/collars should be allocated, etc. Considering the non-linearity of the rolling process and its incremental nature (say from 5 to

13、50 passes to achieve a final section), thecomplex synergies between material complex interactions between direct experienced and specialist designersflow, composition, thermal dependencies and the and indirect draughting in section rolling, only will be successful to undertake complex designs.Detail

14、ed knowledge of the mill capabilities and behaviour (stand stiffnesses, etc.) andoperational constraints (due to mill layout) will also be required. It is also not possible to predict dynamically the behaviour of the rolled section, and as such, the traditional design process is very much considered

15、 as a 2D static and iterative process. Mathematically, the process is much more interesting as it can be described as a non-linear constrained optimisation problem. An effective roll designer will be therefore an individual able to follow a design procedure (rules) by exploiting and linking a range

16、of possibilities and making decisions within given mill constraints. However, although design rules have been developed for many families of sections (e.g. larssen piling, light beams, columns, etc.), some of these rules may be too specific, i.e. it is difficult to decouple the process, product and

17、the mill and the window in which these rules have been developed (temperature, steel grades, etc.) may be too narrow. Opportunity to rationalise rules within a family of products (e.g. piling) within a mill and ultimately across mills is key to successful flexibility and modern rolling production of

18、 long products. In addition, the design process is often time consuming mostly for complex sections (up to 6 months inc. initial rolling) and has to be repeated if the feedstock shape changes. Although, the use of CAD technology has reduced the drawing process, the roll designer is still required to

19、 carry out repetitive tasks, constraining his time to enhance existing designs, but also to explore new product developments and what-if scenarios. In order to speed-up product developments (as well as mill trial time), there is therefore a drive to reduce design time, i.e. the iterative process of

20、design (right first time). This drive has to be combined with a reduction in time for roll and guide system manufacturing and improved synergies with commercial and production personnel, if new products have to be developed faster.Some of the challenges facing roll design are therefore to:-rapidly e

21、ncapsulate in an explicit way the knowledge and expertise of current expert designersspeed-up execution of new designs by the use of a structured and traceable approach-P01/2-free time for creative thinking (new products) and optimisation of current products and processesoptimise/standardise current

22、 design rules and improve their modularity and breath of applications (e.g. application to controlled rolling, new steel grades, etc.) in order to fully exploit the envelope of processing conditionsgradually move from process to product optimisation by considering product properties as an objective/

23、constraint for roll design optimisationcombine the existing roll design process with user-friendly numerical simulations and knowledge-based system as to provide a modern platform for a new generation of roll designers or design engineersdevelop an environment for easy incorporation of design within

24、 the development process,i.e. roll and guide design, R&D, commercial and production enhance breath and depth of engineering and rolling knowledge-Since 1997, in order to address some of these challenges, Corus CC&I has been developing a methodology for roll design centered around a knowledge elicita

25、tion and management process. A method for rule gathering and analysis has been applied using structured interviewing techniques involving the current expert designers. Each experienced roll designer has been allocated a trainee designer as a rule gatherer. It became clear that a knowledge-based syst

26、em (KBS) based on Object Oriented technology (OO) and close coupled to the CAD system would be the correct platform for encapsulating this explicit knowledge. The aim of the knowledge driven system is not only to provide a modularplatform for recording and managing rules and relationships between ea

27、ch sequential part of the process, but also to automatically mimic the process of roll design (i.e. the generation of the roll shape pockets) based on the methodology and constraints briefly described above.OO based systems overcome many deficiencies of traditional expert systems by using objects, c

28、lasses, etc. and allowing inheritance of attributes between objects (forward, backward). This system, still under development, has so far focused on current families of sections, such as beams, angles, piling and rails. The KBS system is bi-directional to the CAD MICROSTATION environment via MDL. Ex

29、isting geometry databases and symbols can be used from the CAD, therefore reducing repetitive tasks within the KBS system.Further development of the underlying structure and rules are required to allow manufacturing of a similar product family on different mills and to expand the links with the FEM

30、engine. An example of a developed system for a section mill and beam product is shown in Figure 1.Figure 1: Example of KBS environment for beam mill level structure)(high to lowP01/3On a related front, mathema tical modelling of rolling processes has advanced significantly over the last decade 2,3,4

31、. Corus at its Technology Centres has been involved in the field of finite elements (FE) and metal forming for the last past 20 years, with the development of in-house FE codes and since 1989 the use of the ABAQUS commercial code. Following advances made in the use and development of FE and graphica

32、l user interface (GUIs) as a tool for roll pass design 5 initially off-line, it became apparent that such technology could be transferred from an off-line expert environment to an advisory and optimisation system for steel works personnel. A recent review 6 showed that greater benefits of the use of

33、 modelling techniques could be made if a dual strategy combining both development of local models (e.g. material constitutive models, microscopic modelling of scale and heat transfer phenomena, etc.) and through process models (TPM) could be set-up and targeted to address both off-line and Works env

34、ironment. Therefore, in parallel to the development of the KBS system in 1997, a joint- development between Corus, CC&I and HKS has been initiated to provide an integrated rolling mill simulation system for roll pass design. Running on Silicon Graphics Origin 2000 and NT Desktop platforms, the fully

35、 commissioned system is being used in production by roll design engineers to optimise the hot rolling process for a wide range of steel sections. This project has involved a co-ordinated effort between Corus, HKS and SGI to develop a suitable user friendly interface (GUI), and optimise the model bui

36、lding, the analysis functionality, and the software & hardware performance in order to provide a highly flexible and powerful simulation tool. The FE/GUI simulator is linked to the CAD/KBS system, providing a broad range of advanced analysis capabilities for the rolling mill engineers. A schematic o

37、f the roll design environment is illustrated below (Fig.2).Figure 2: Schematic of roll pass design environmentThe overall environment (still under development) comprises of the CAD, KBS andGUI/CAE systems running on NT dual screen CAD including the ABAQUS/CAE kernel, is running on SGIworkstations. T

38、he analysis system, Origin 2000 Unix supercomputer. links (both ways) to the FE GUIThe sovereign package is the CAD system, ensuringenvironment. An additional customised CAD interface had to be built to allow import, export and tracking of FE results with automatic facilities for generating clean an

39、d compatible iges files with ACIS file format.P01/4This paper is therefore aimed at describing some of the key features of this simulation system and the way the system is being used in design production.2. ANALYSIS SYSTEM DESCRIPTIONThe roll pass design analysis (rpdi) system has four main componen

40、ts, an advanced and user-friendly GUI based on a customised version of the CAE environment running on NT systems, an advanced solver engine based on an enhanced ABAQUS Explicit Dynamicssoftware running on UNIX system , an advanced interpass processing ABAQUS Explicit and Standard and a new controlle

41、r/driver handling tracking information flow through the various ABAQUS packages.enginelinkingsubmission andThis project has involved the development of several advancedfeatures in theABAQUS analysis codes. The adaptivity capability in ABAQUS/Explicit has been enhanced to provide superior modelling o

42、f the large deformations involved in multi-pass rolling; a coupled temperature-displacement capability has been added to the explicit product; and various key features have been developed to improve the efficiency of the rolling simulation, such as an automatic steady state control detection. Accura

43、te and faster 8 noded brickselements have also been developed (with stiffness hourglass control), together with a suite of additional features (analytical rigid surface, tracer particles, slip velocity and displacement, enhanced friction laws, etc.). In addition, the enhancements to the import capab

44、ility have allowed the implicit code, ABAQUS/Standard to be used at key stages during the simulation, with data being transferred between the implicit and explicit solvers for interpass heat transfer analysis.The rpdi system is based on the concept of schedules and simulations. A schedule identifies

45、 the sequential flow of the feedstock though the mill layout and therefore identifies the sequence of stands, rolls and grooves (or pockets). A simulation allows the designers to submit a single or multi-pass analysis from a given schedule. The overall environment is based on mill, product, sections

46、, roll and material libraries , allowing the designers to build schedules from pre-existing mill databases, which encapsulate all the default parameters for a mill layout (e.g. stands, grooves, speed, material, etc.). Two-high and universal mills can currently be analysed by the system. In the case

47、of universal and edger mills, a parametric facility to build rolls from geometrical parameters (see KBS) is also provided. The system allows easy recording and tracking of information via pre-selected tags/user information. Thesystem is closely linked to the CAD environment via a customisedinterface

48、 for bothimport/export of rolls and 2D cross sections. The current geometric transfer file format is IGES. Figure 3 shows a typical view of the rpdi GUI interface.P01/5Figure 3 : rpdi GUI and schedule manager informationSchedules and simulations are decoupled, allowing flexibility in analysis. The s

49、ystem is highly modular and provides all the possible combinations for through process roll design analysis. Transient and steady solutions are obtained automatically from a single simulation allowing the designers not only to optimise his schedule/roll profiles on steady state results but also on t

50、ransient (entry conditions, delivery, etc.). Isothermal single or multipass analyses could for instance be carried out, similarly the designers could opt for interpass cooling, therefore allowing computation and mapping of temperature distribution to the rolling simulation or ultimately full thermo-

51、coupling could be selected, allowing computation of heat loss due to roll conduction. Pure heat transfer analysis is also provided giving the possibility of thermal run down taking into account thermal boundaries from ancillary equipments such as descaler, water boxes, etc. Automatic design sensitiv

52、ity capabilities are also provided allowing the designers to study the sensitivities of its design to key parameters, such as rolling and pitch line, temperature, entry conditions, roll diameters, and so on.The system is also highly flexible and user-friendly allowing the designers to start analyses

53、 say for instance from an initial parametric feedstock (bloom, slab, etc.), design CAD product profiles or intermediate FE computed deformed shapes. This flexibility is consistent with the way a roll designer works, i.e. an incremental and iterative process, involving tuning where appropriate at sel

54、ected passes/grooves. Intelligence is provided for tracking all information and state variables for intermediate restart simulations.Once a designer has constructed and/or selected a schedule (min 1 pass) for a particular mill/product/section, and defined his analysis intent via the form selection,

55、the rpdi CAE kernel builds automatically the first pass analysis (part assembly, contact, meshing, boundary conditions, mapping, input deck), submit the job to the ABAQUS/Explicit solver until a steady state deformation is achieved. An interpass module then analyses the temperature drop as the stock

56、 is transferred to the next pass, depending on the simulation description. The steady state section is then splined and re-used to create a new 3D model of the deformed stock that is fed into the next roll pass. This cycle of rolling and steady state (ss) deformation is continued through the multipl

57、e roll passes in the schedule until the final deformed shape isP01/6achieved. Final or interactive results (ss shapes, load, torque, 2D, 3D properties) can be easily visualised within the rpdi environment. Facilities for recording results of simulation have been built into the system together with e

58、xport facilities of iges 2D product profiles to the CAD package. Although not currently considering the concept of metadatafile, the system is being enhanced to allow full encapsulation of simulation and results information. This aspect is key for quality assurance. A schematic of the rpdi system is

59、 illustrated below (Fig.4)Figure 4: Schematic view of rpdi systemTwo key features of this project have been first of all the design and development of the powerful interface and secondly the underlying intelligence for the automatic simulation construction and analysis. Effort and time was spent in the definition of the user and functional specif