Modelling of friction with respect to size effects

Hu, Zhenbang; Vollertsen, Frank

doi:10.1007/s12289-008-0164-3

Cited by 17 publications

(8 citation statements)

References 4 publications

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“…Compared to the usual deviation of punch force described in [15], the deviation of the punch force in this investigation is much larger. This could be caused by the property of the used blank material, i. e. the tiffany structure, Figure 7.…”

Section: Discussioncontrasting

confidence: 64%

Effect of heat treatment on the hardness of micro deep drawn cups of Al‐2Sc

Bargen¹,

Zoch

et al. 2011

Materialwissenschaft Werkst

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Continuous miniaturisation of products e. g. for the automotive or the microelectronic sector necessitates process chains, which allow the manufacturing of microscopically small components in high quantities. The development of required processes and technologies is the aim of the Collaborative Research Centre (CRC) 747 "Micro Cold Forming" of the German Research Foundation. Besides micro cold forming another necessary step in the manufacturing process chain is the heat treatment process that enables the adjustment of materials properties being suitable for cold forming. Finally the application properties also have to be adjusted e. g. by precipitation hardening of aluminium alloys to increase the strength above the strain hardened level. Within the CRC an advanced Al-Sc alloy with 2 mass-% Scandium was developed to achieve particular properties. According to the very high Sc content dissolved a greater number of fine and homogeneously distributed precipitates causing a significant strengthening effect will be formed during artificial ageing. To meet the requirements of a high production rate the ageing of the micro deep drawn cups (1 mm in diameter) was performed in very short time in a drop-down tube furnace. Before and after ageing the cups were characterised by ultra micro hardness measurements.Keywords: Micro deep drawing / Limit drawing ratio / Short time artificial ageing / Al-2Sc / In der Produktion von Mikrobauteilen nehmen die Anforderungen in Bezug auf Baugröße (Miniaturisierung), Stückzahl, Stückpreis und Qualität immer mehr zu. Die dabei auftretenden Herausforderungen werden, im von der Deutschen Forschungsgemeinschaft geförderten Sonderforschungsbereich 747 "Mikrokaltumfomen", an der Universität Bremen interdisziplinär angegangen. Einer der elementaren Fertigungsschritte in der Prozesskette, neben der Mikrokaltumformung, ist die Wärmebehandlung. Zum einen dient sie der Einstellung von Gefügeeigenschaften, die eine Kaltumformung, mit möglichst geringem Energie-und Krafteinsatz ermöglichen. Zum anderen muss nach der Umformung in vielen Fällen das Werkstück noch einmal für den späteren Bauteileinsatz wärmebehandelt werden, um die Festigkeit über den kaltverfestigten Zustand hinaus zu steigern. Innerhalb des SFB wurde eine besondere Aluminium-Scandium Legierung mit speziellen Eigenschaften entwickelt. Aufgrund des sehr hohen zwangsgelösten Sc-Gehalts von bis zu 2 mas.-% ist es möglich, während einer Warmauslagerung eine große Anzahl feiner homogen verteilter festigkeitssteigernder Ausscheidungen zu bilden, die eine signifikante Verfestigung bewirken. Aus dieser Legierung wurden mittels Mikrotiefziehen Näpfe (Durchmesser 1 mm) produziert. Um der Anforderung nach einer hohe Produktionsrate gerecht zu werden, wurden die Näpfe anschließend in einem neu entwickelten Fallrohrofen kurzzeitwarmausgelagert. Die Näp-fe wurden nach der Umformung und der Kurzzeitwärmebehandlung mittels Ultramikrohärte-messungen charakterisiert.

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Section: Discussioncontrasting

confidence: 64%

Effect of heat treatment on the hardness of micro deep drawn cups of Al‐2Sc

Bargen¹,

Zoch

et al. 2011

Materialwissenschaft Werkst

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“…R-Squared, Adj R-Squared, Pred R-Squared and Adeq Precision values were also calculated, Table 4. Mentioned statistical terms are often used in statistical analysis and they show that model obtained in this research is significant [24]. For maximum drawing force prediction overall 9 significant mathematical models can be derived, Table 3.…”

Section: Results Analysis and Discussionmentioning

confidence: 76%

Mathematical modelling of an experimental‐analytical method for friction coefficient determination in deep drawing

Lela

Krolo

Mirić

2019

Materialwissenschaft Werkst

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The main aim of this paper is to determine the friction coefficient μ and maximum drawing force in deep drawing process of aluminum alloy EN AW 1050 utilizing strip drawing method. Influence and interaction between lubrication condition, blank holder force and strip surface roughness on maximum drawing force and friction coefficient are investigated. Response surface methodology and D‐Optimal design are utilized in order to create an experimental plan. According to the design, 23 strip drawings experiments are performed and statistical analysis was done. The regression and variance analysis results with 18 significant mathematical models which are derived in order to describe influence of mentioned parameters on friction coefficient and maximum drawing force. Results are discussed according to previous research. Finally, the optimization of processing parameters is performed aiming for lower friction coefficient and maximal drawing force.

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“…The software ABAQUS 6.9.3 was used to simulate the forming process. In previous works [10,11] friction functions were acquired from experimentally measured punch force vs. stroke curves in scaled deep drawing of circular parts. Here, the tools were defined as analytical rigid shell and the blank was defined as deformable object.…”

Section: Methods Of Investigationmentioning

confidence: 99%

Optimisation of the blank shape for micro deep drawing of rectangular parts

Hu¹,

Vollertsen²

2011

AIP Conference Proceedings

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In this investigation the blank shape for micro deep drawing of rectangular parts was for the first time optimized using FEM method with consideration of the real process conditions in micro forming, i.e. the coefficient of friction and the flow curves of thin foils. The acquired optimized blank shape was then validated by applying it to experiments. For both numerical and experimental investigations a punch with a section of 2 x 1 mm 2 was used. Aluminum Al99.5 with a sheet thickness of 20 µm was used as blank material in this investigation. A flange free drawn part was successfully obtained from experiment using the blank shape and blank holder force optimized using FEM.

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Modelling of friction with respect to size effects

Cited by 17 publications

References 4 publications

Effect of heat treatment on the hardness of micro deep drawn cups of Al‐2Sc

Effect of heat treatment on the hardness of micro deep drawn cups of Al‐2Sc

Mathematical modelling of an experimental‐analytical method for friction coefficient determination in deep drawing

Optimisation of the blank shape for micro deep drawing of rectangular parts

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