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Characterizing the Elastic Behaviour of a Press Table throughTopology Optimization
Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering.
Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering.
Blekinge Institute of Technology, Faculty of Engineering, Department of Mechanical Engineering.
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2017 (English)In: Journal of Physics: Conference Series / [ed] Volk W., Institute of Physics Publishing (IOPP), 2017, Vol. 896, article id 012101Conference paper, Published paper (Refereed)
Abstract [en]

Sheet metal forming in the car industry is a highly competitive area. The use ofdigital techniques and numerical methods are therefore of high interest for reduced costs andlead times. One method for reducing the try-out phase is virtual rework of die surfaces. Thevirtual rework is based on Finite Element (FE) simulations and can reduce and support manualrework. The elastic behaviour of dies and presses must be represented in a reliable way in FEmodelsto be able to perform virtual rework. CAD-models exists for nearly all dies today, butnot for press lines. A full geometrical representation of presses will also yield very large FEmodels.This paper will discuss and demonstrate a strategy for measuring and characterizing apress table for inclusion in FE-models. The measurements of the elastic press deformations iscarried out with force transducers and an ARAMIS 3D optical measurement system. The presstable is then inverse modelled by topology optimization using the recorded results as boundaryconditions. Finally, the press table is coupled with a FE-model of a die to demonstrate itsinfluence on the deformations. This indicates the importance of having a reliable representationof the press deformations during virtual rework.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2017. Vol. 896, article id 012101
Keywords [en]
Automotive industry, Finite element method, Flanges, Fracture, Fracture testing, High strength steel, Materials testing, Metal forming, Metal testing, Metals, Strain
National Category
Applied Mechanics
Identifiers
URN: urn:nbn:se:bth-15394DOI: 10.1088/1742-6596/896/1/012068ISI: 000424196000068OAI: oai:DiVA.org:bth-15394DiVA, id: diva2:1153439
Conference
36th IDDRG-2017 - MATERIALS MODELLING AND TESTING FOR SHEET METAL FORMING, MUNICH
Funder
VINNOVA, 2016-03324
Note

open access

Available from: 2017-10-30 Created: 2017-10-30 Last updated: 2018-02-22Bibliographically approved
In thesis
1. Elastic Press and Die Deformations in Sheet Metal Forming Simulations
Open this publication in new window or tab >>Elastic Press and Die Deformations in Sheet Metal Forming Simulations
2017 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Never before has the car industry been as challenging, interesting, and demanding as it is today. New and advanced techniques are being continuously introduced, which has led to increasing competition in an almost ever-expanding car market. As the pace and complexity heightens in the car market, manufacturing processes must advance at an equal speed.

An important manufacturing process within the automotive industry, and the focus of this thesis, is sheet metal forming (SMF). Sheet metal forming is used to create door panels, structural beams, and trunk lids, among other parts, by forming sheets of metal in press lines with stamping dies. The SMF process has been simulated for the past couple of decades with finite element (FE) simulations, whereby one can predict factors such as shape, strains, thickness, springback, risk of failure, and wrinkles. A factor that most SMF simulations do not currently include is the die and press elasticity. This factor is handled manually during the die tryout phase, which is often long and expensive.

The importance of accurately representing press and die elasticity in SMF simulations is the focus of this research project. The research objective is to achieve virtual tryout and improved production support through SMF simulations that consider elastic die and press deformations. Loading a die with production forces and including the deformations in SMF simulations achieves a reliable result. It is impossible to achieve accurate simulation results without including the die deformations.

This thesis also describes numerical methods for optimizing and compensating tool surfaces against press and die deformations. In order for these compensations to be valid, it is imperative to accurately represent dies and presses. A method of measuring and inverse modeling the elasticity of a press table has been developed and is based on digital image correlation (DIC) measurements and structural optimization with FE software.

Optimization, structural analysis, and SMF simulations together with experimental measurements have immense potential to improve simulation results and significantly reduce the lead time of stamping dies. Last but not least, improved production support and die design are other areas that can benefit from these tools.

Abstract [sv]

Aldrig tidigare har bilindustrin varit så utmanande, intressant och spännande som idag. Ny och avancerad teknik introduceras i en allt snabbare takt vilket leder till ständigt ökande konkurrens på en, nästan ständigt, ökande bilmarknad. Den ständigt ökande komplexiteten ställer även krav på tillverkningsprocesserna.

En viktig process, som denna licentiatuppsats fokuserar på, är pressning av plåt. Tillverkningstekniken används för att forma plåtar till dörrpaneler, strukturbalkar, motorhuvar, etc. Plåtar formas med hjälp av pressverktyg monterade i plåtformningspressar. Plåtformningsprocessen simuleras sedan ett par decennium tillbaka med Finita Element (FE) simuleringar. Man kan på så sätt prediktera form, töjningar, tjocklek, återfjädring, rynkor, risk för försträckning och sprickor m.m. En faktor som för tillfället inte inkluderas i näst intill alla plåtformningssimuleringar är elastiska press- och verktygsdeformationer. Detta hanteras istället manuellt under, den oftast långa och dyra, inprovningsfasen.

Detta projekt har visat på vikten av att representera press och verktygsdeformationer i plåtformningssimuleringar. Detta demonstreras genom en analys av ett verkligt pressverktyg som belastas med produktionskrafter. Det är inte möjligt att uppnå bra simuleringsresultat utan att inkludera verktygsdeformationer i simuleringsmodellen.

Uppsatsen beskriver även numeriska metoder för att optimera och kompensera verktygsytor mot press och verktygsdeformationer. För att dessa kompenseringar ska stämma är det viktigt att man representerar både verktyg och press på ett korrekt sätt. Förslag på en metod för att mäta och inversmodellera pressdeformationer har utvecklats, metoden är baserad på mätningar med DIC-systemet ARAMIS och optimering i FE-mjukvaror.

Optimering, strukturanalys, och plåtformningsanalys tillsammans med experimentella mätningar har en stor potential att förbättra plåtformningssimuleringar samt reducera ledtiden för pressverktyg. Sist men inte minst, andra positiva effekter är en enklare och smidigare konstruktionsprocess och förbättrad produktionssupport.

Place, publisher, year, edition, pages
Karlskrona: Blekinge Tekniska Högskola, 2017
Series
Blekinge Institute of Technology Licentiate Dissertation Series, ISSN 1650-2140 ; 2
Keywords
Sheet Metal Forming, Stamping Die, Stamping Press, Structural Analysis, Finite Element Simulation, Optimization, Digital Image Correlation, Inverse Modeling
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:bth-15481 (URN)978-91-7295-345-1 (ISBN)
Presentation
2017-12-14, 10:00 (Swedish)
Opponent
Supervisors
Funder
VINNOVA, 2016-03324
Available from: 2017-11-10 Created: 2017-11-10 Last updated: 2017-12-08Bibliographically approved

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