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COB131 DETERMINAÇÃO DE ABERTURAS ENTRE CILINDROS DE LAMINAÇÃO, VIA LÓGICA NEBULOSA / DETERMINATION OF THE ROLLING MILL GAP BY USING FUZZY LOGIC

Carmen Déa Moraes Pataro & Horacio Helman

Departamento de Engenharia Eletrônica, Escola de Engenharia da UFMG

Av. Antonio Carlos, 6627, Belo Horizonte, MG, Brasil, CEP 30.161-970. - E- mail: Carmen@eee.ufmg.br

In the present work, a method for the determination of the rolling mill gap of flat products by using fuzzy logic was developed. The rolling mill gap is determined by considering the aimed and accumulated deformations, classified as "high", "medium" and "low". The rules to decide the corresponding actions are obtained from the input data. This schedule is non-dependent upon the knowledge of the mechanical properties of the material to be rolled and the characteristics of the rolling process.

Keywords: Rolling Process , Fuzzy Logic, Laminação, Lógica Nebulosa

COB161 ANÁLISE COMPARATIVA DE ESTIRAMENTO IN-PLANE VERSUS OUT-OF-PLANE/COMPARATIVE ANALYSIS OF IN-PLANE VERSUS OUT-OF-PLANE STRETCHING

Fernando Ferreira Fernandez & Hazim Ali Al-Qureshi

Departamento de Tecnologia, Instituto Tecnológico de Aeronáutica- ITA-CTA

CEP 12228-900 São José dos Campos, Brasil- E-mail: hazim@mec.ita.cta.br

The limit strains, or the maximum plastic strains that a sheet can support up to the necking point, admitting free deformation on the sheet plane (In plane strains-IP) are quite different of the biaxially stretching operations with spherical punch or pressure (Out of plane strains-OP). The last one, which represents the real industrial operations, are greater than the IP strains, for the same degree of biaxial tension. The main scope of this work is to perform stretch operations IP, using a specially designed device able to input IP strains, and verify if differences between theoretical models and experimental data are based on the fact the stretching operation be IP or OP.

Keywords: Chapas metálicas, Estiramento Biaxial, Deformações limites. Sheet metals, Biaxially stretching, Limit strains

COB377 PROCESSO DE FABRICAÇÃO POR CONFORMAÇÃO SUPERPLÁSTICA EM CHAPAS DE TITÂNIO / FABRICATION PROCESS BY SUPERPLASTIC FORMING IN TITANIUM SHEETS

Augusto Eduardo Baptista Antunes

Universidade Estadual Paulista-UNESP, Alameda das Rosas, 79, 12223-900 - e-mail lidia@ieav.cta.br , São José dos Campos/SP

In this work, activities related to application of superplastic forming technics, in getting pieces with titanium alloy sheets of the type Ti 6Al 4V, are presented and discussed. The results show that the forming process presents no difficulties. But, the whole set of the accessories and the artifice to get good performance of the process involve technics that must be well controlled and improved, depending on the size or complexity fo the piece worked. The equipments and devices to prepare the experiments were particularly designed and constructed to the purpose, and suffered constantly modifications to attend improvements and propitiate versatility and producibility during the course of the activities. The gotten pieces showed a good finishing and possibility of a good dimensional precision. The much more interesting result of the experiment was the experience obtained during the development of the process and so, we intend to present its many stages, technical characteristics and the potential application in differents industrial segments.

Keywords: Superplastic Forming, titanium alloys.

COB393 EXPERIMENTAL DETERMINATION OF FRICTION COEFFICIENT AND STRESS-STRAIN CURVE FOR APPLICATION IN METAL FORMING ANALYSES

Alexandre Farina Marcon, Eduardo Bittencourt & Guillermo Juan Creus

CEMACOM / CPGEC / PROMEC, Escola de Engenharia - UFRGS - CEP 90035-190 Porto Alegre, RS, Brasil

E-mail: marcon@vortex.ufrgs.br

The compression test of a ring is customarily used to determine the friction coefficient in metal forming problems. The aim of this work is to develop a procedure to obtain, for metals in large deformation, the stress-strain curve and the friction coefficient through the same ring test. The friction coefficient is evaluated comparing curves obtained by a finite element code with the experimental curves. The stress-strain curve is obtained inverting an analytic solution, calculated by the lower upper-bound approach.

Keywords: Friction, Stress-strain curve, Ring test, Large deformation

COB548 NUMERICAL AND EXPERIMENTAL ANALYSES OF FORMING AND PENETRATION PROBLEMS

Franco Olmi, Eduardo Bittencourt & Guillermo Juan Creus

CEMACOM/CPGEC/PROMEC, Escola de Engenharia, UFRGS.

CEP 90035-190 – Porto Alegre, RS, Brasil – E-mail: olmi@vortex.ufrgs.br

In this work the large elasto-plastic deformations taking place in metal forming and impact are analyzed, using numerical and experimental procedures. Initially, the procedures used for remeshing and transference of variables are described. Then, the analyses of two practical problems are performed, using the code METAFOR (METAl FORming). The first corresponds to a forming operation using alternatively one and two forging stages. In the second one, the penetration of a steel conic head into an aluminum cylinder is analyzed, both numerically and experimentally. It is seen that, for this kind of applications, remeshing is indispensable to obtain adequate final solutions.

Keywords: Finite elements method (FEM), large elasto-plastic deformations, remeshing.

COB575 Analysis of Metal Forming Processes Based on a Reproducing Kernel Particle Method

Cristina Maria Oliveira Lima Roque, Sérgio Tonini Button

Department of Mechanical Engineering, State University of Campinas, Campinas, SP, 13083-970, caixa postal 6122, Brazil

e-mail: crism@fem.unicamp.br

Jiun-Shyan Chen, Chunhui Pan

Department of Mechanical Engineering and Center for Computer-Aided Design, The University of Iowa, Iowa City, Iowa 52242, USA

e-mail: jschen@icaen.uiowa.edu

The excessive plastic deformation during metal forming processes exhibits characteristics of both solid and fluid flow, and conventional finite element methods often break down due to severe mesh distortion. Since 1993, considerable research work in computational mechanics has been devoted to the development of meshless methods. The main feature of these methods is that the domain of the problem is represented by a set of nodes, and finite element mesh is totally unnecessary. This new generation of computational methods reduces time-consuming model generation and refinement effort, and provides a higher rate of convergence than that of the conventional finite element methods. A meshless method based on the reproducing kernel particle method is applied to metal forming analysis. With this method, the model refinement in metal forming simulation can be done simply by inserting nodes without remeshing. Metal forming examples, such as sheet metal stamping and upsetting, are analyzed to demonstrate the performance of the method.

Keywords: Meshless Method, Reproducing Kernel Particle Method, Metal Forming, Elasto-Plasticity, Large Deformation.

Método sem malha, Método RKPM, Conformação Mecânica, Elasto-plasticidade, Grandes deformações.

COB577 SISTEMA ESPECIALISTA PARA FORJAMENTO A QUENTE / expert system for hot forging design

Ângelo Caporalli Filho, Luciano Antonio Gileno, Sérgio Tonini Button

Departamento de Engenharia de Materiais, Faculdade de Engenharia Mecânica - UNICAP

CEP 13083-970 - Campinas, S.P. Brasil, E-mail: sergio1@fem.unicamp.br

Planning hot forging process is a time-consuming activity with high costs involved, because of the trial-and-error iterative methods used to design dies and to choose equipments and process conditions. Some processes demand many months to produce forged parts with controlled shapes, dimensions and microstructure. This paper shows how expert systems can help engineers to reduce the time needed to design precision forged parts and dies from machined parts, with the software APFFQ interfacing Visual Basic v.4.0 and SolidEdge v.2.0. The software was used to design flashless hot forged gears, chosen from families of gears.

Keywords: Precision Forging, Expert Systems, Hot Forging. / Forjamento de precisão, Sistemas Especialistas, Forjamento a Quente

COB590 Ação de controle sobre a espessura de saída de tiras laminadas utilizando a lógica nebulosa / control aCTION on THE rolled strips THICKNESS USING fuzzy LOGIC

Regina Fátima Gibson Gonçalves¹ & Horacio Helman²

¹Departamento de Engenharia Elétrica, EEUFMG. - Av. Antônio Carlos, 6627. Caixa Postal 209

CEP: 30.161-970 Belo Horizonte, MG. - E-mail: goncalve@cce.ufmg.br

²Departamento de Engenharia Metalúrgica, EEUFMG. - R. Espírito Santo, 35. -

CEP: 30.160-010 Belo Horizonte, MG. - E-mail: hhelman@demet.ufmg.br

The thickness of a rolled strip, which must remain within very close limits, is one of the critical parameters in the characterization of its quality. The process of controlling this thickness frequently requires actions which may affect other important characteristics of the strip, such as profile and shape. Two control procedures are commonly used for this purpose, one on the screw-down mechanism and the other on the strip front or back tensions. One or the other may be more adequate, depending on the operational conditions. These control actions have been normally determined and executed in correspondence with the variation of only one of the parameters of the process. In the present work, a method is developed based on the application of fuzzy logic, which allows for the calculation of suitable control actions to adjust the final thickness of the strip, considering the simultaneous variation of any two operational parameters of the process.

Keywords: Strip rolling, gage control, fuzzy logic, laminação de tiras, controle de espessura, lógica nebulosa.