Analysis of Axisymmetric Cup Forming of Metal Foil and Micro Hydroforming Process

A novel forming method “micro hydromechanical deep drawing (MHDD)” is focused to improve the tribological property and forming limit. In this study, a theoretical model for MHDD is developed to investigate the size effect on deformation behavior in micro hydromechanical deep drawing. The effects of fluid pressure, the difference of friction coefficients at inner pockets and outer pockets are considered in the investigation on the size effect of tribological property. The friction force decreases as the scale factor decreases in MHDD process. It is also found that the tribological property in micro scale can be improved by applying the fluid pressure. The forming limit decreases as the relative punch diameter increases. However, it is clarified that the forming limit can be improved by decreasing the friction force in MHDD.

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An experimental study on the cryogenic face seal at different inlet pressures

Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology ◽

10.1177/1350650119896455 ◽

2019 ◽

Vol 234 (9) ◽

pp. 1470-1481

Author(s):

Guoyuan Zhang ◽

Yangyang Zhao ◽

Weigang Zhao ◽

Xiutian Yan ◽

Maotan Liang

Keyword(s):

Friction Coefficient ◽

Friction Force ◽

High Speed ◽

Fluid Pressure ◽

Stable State ◽

Test System ◽

Leakage Rate ◽

Mechanical Seals ◽

Closing Force ◽

The Difference

An experimental test system for cryogenic high-speed hydrodynamic non-contact mechanical seals is developed. Based on this system, the performances of seals under different working conditions are studied in detail in this paper. With the experimental results, the main performances of the seals (such as inlet and outlet temperatures, separated speed, face temperature, friction force, friction coefficient, leakage rate) are obtained, and the relationships of the performances with the inlet fluid pressure, the closing force and the rotational speed are discussed. The results show that the difference between the outlet and inlet temperatures decreases with increasing inlet fluid pressure. As the speed increases, the friction force varies little and remains at a constant value. The friction coefficient of the seal is approximately 0.12 and basically does not change with the speed. The leakage rate is also maintained at approximately 190 g/s. With the increase in the closing force, the friction at the seal’s face does not change greatly, which indicates that the friction at the face is always in a stable state with the seal’s closing force.

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Determination of Forming Limit Diagrams for Thin Foil Materials Based on Scaled Nakajima Test

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.794.190 ◽

2015 ◽

Vol 794 ◽

pp. 190-198 ◽

Cited By ~ 4

Author(s):

Stefan Veenaas ◽

Gerrit Behrens ◽

Konstantin Kröger ◽

Frank Vollertsen

Keyword(s):

Stress State ◽

Deep Drawing ◽

Axial Stress ◽

Forming Limit Diagram ◽

Thin Foil ◽

Chromium Steel ◽

Forming Limit ◽

Metal Foil ◽

Forming Limit Diagrams ◽

Process Understanding

For a better process understanding of micro deep drawing processes and reliable prediction of component failure in FE simulations, it requires the most accurate knowledge of actual material behaviour. However, it is not sufficient to describe material failure for a multi axial stress state in deep drawing using a mechanical parameter as the elongation from tensile test. A forming limit diagram and a forming limit curve are more suited to describe the limit of formability under deep drawing stress state conditions. Methods like hydraulic or pneumatic bulge tests are available to determine forming limit curves even for thin metal foil materials. Nevertheless, using these methods only positive minor strains can be achieved. Especially for a deep drawing process negative minor strains and the left side of a forming limit diagram are more important. Therefore, in this study, experiments based on scaled Nakazima tests were performed to determine complete forming limit diagrams for different foil materials with a thickness range of 20 µm to 25 µm. Scaling the test setup improves the handling of thin specimens. Results with a higher local resolution and the specimens’ size is much closer to the actual size of a micro deep drawn component. Using this testing method forming limit diagrams for the materials Al99.5, E-Cu58, stainless austenitic nickel-chromium steel X5CrNi18-10 (1.4301 / AISI 304), all produced by rolling, and an Al-Zr-foil, produced by a PVD sputtering process, were determined for the micro range.

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Forming Limit of Magnesium Alloy Sheet in Hydromechanical Deep Drawing

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.482-484.2086 ◽

2012 ◽

Vol 482-484 ◽

pp. 2086-2089 ◽

Cited By ~ 1

Author(s):

Xian Chang Mao ◽

Ming Guang Wang

Keyword(s):

Magnesium Alloy ◽

Internal Pressure ◽

Deep Drawing ◽

Alloy Sheet ◽

Forming Limit ◽

Az31b Magnesium Alloy ◽

Hydromechanical Deep Drawing ◽

Magnesium Alloy Sheet ◽

Deformation Behaviors ◽

Az31b Magnesium Alloy Sheet

The experimental research on the hydromechanical deep drawing of AZ31B magnesium alloy sheet was conducted in this paper. The deformation behaviors and the influence of internal pressure on its formability are investigated, moreover, the fracture behaviors of the obtained workpieces are discussed. The experimental results show that the formability of AZ31B magnesium alloy sheet in hydromechanical deep drawing is poorer than that in mechanical deep drawing at room temperature because the internal pressure fails to work effectively due to the weak plastic deformation capacity and the premature fracture of the kind alloy.

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Numerical modeling of size effect in micro hydromechanical deep drawing

10.1063/1.4850121 ◽

2013 ◽

Cited By ~ 2

Author(s):

Hideki Sato ◽

Ken-ichi Manabe ◽

Dongbin Wei ◽

Zhengyi Jiang

Keyword(s):

Numerical Modeling ◽

Size Effect ◽

Deep Drawing ◽

Hydromechanical Deep Drawing

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Finite Element Analysis of Size Effect for Forming-Limit Curves

Acta Materialia Transilvanica ◽

10.33924/amt-2020-02-02 ◽

2020 ◽

Vol 3 (2) ◽

pp. 65-69

Author(s):

Viktor Gál

Keyword(s):

Finite Element ◽

Size Effect ◽

Forming Limit Diagram ◽

Standard Test ◽

Forming Limit ◽

New Materials ◽

Element Analysis ◽

Test Pieces ◽

The Difference ◽

Forming Limit Curves

AbstractNowadays, finite element (FE) methods are widely used for the analysis of Body in White parts production. An FE software applies the forming-limit diagram to predict the failure of the sheet metal. There are many new materials for weight reduction; for these new materials, the determination of forming-limit curves (FLC) is important to studying formability issues. There are some cases where the available material for the measurements is not enough or due to some specific measurement parameter, the standard test specimen cannot be used. In these cases, the geometry of the test pieces and the testing equipment should be reduced. In this paper, the material card for DC05 (1.0312) steel was determined based on a tensile test and the Nakajima test. With the material card, simulations were performed to investigate the size effect of the hemispherical punch used for Nakajima forming method. Based on the simulations, the difference between the FLC-s (determined with different equipment) was found to be negligible.

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Micro Sheet Hydroforming Process of Ultra-Thin Pure Titanium Foil

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.626.397 ◽

2014 ◽

Vol 626 ◽

pp. 397-401 ◽

Cited By ~ 3

Author(s):

Hideki Sato ◽

Kenichi Manabe ◽

Dong Bin Wei ◽

Zheng Yi Jiang ◽

Daiki Kondo

Keyword(s):

Stainless Steel ◽

Friction Force ◽

Fluid Pressure ◽

Pure Titanium ◽

Young Modulus ◽

Titanium Foil ◽

Sheet Hydroforming ◽

Hydroforming Process ◽

Titanium Foils ◽

Peeling Off

A micro hydromechanical deep drawing is carried out using the pure titanium and the effect of fluid pressure on formability of pure titanium is investigated. The experiments are performed using the two kinds of pure titanium foils (TR270C-H and TR270C-O) and stainless steel foil (SUS304-H) with 50 thickness and the cylindrical and conical punches. As a result, it is found that the peeling off the oxide film of pure titanium can be reduced by applying the fluid pressure because the friction force and contact pressure between the blank and die decreases. However, the formability is lower for pure titanium than that for stainless steel because the tensile strength is low and the friction force is easy to increase as the friction force increases. In contrast, due to the low young modulus of pure titanium, the restriction of wrinkling, decrease of friction force and friction holding effect can be obtained at low fluid pressure.

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Optimization of Tube Hydroforming Process Using Probabilistic Constraints on Failure Modes

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.62.21 ◽

2011 ◽

Vol 62 ◽

pp. 21-35 ◽

Cited By ~ 2

Author(s):

Anis Ben Abdessalem ◽

A. El Hami

Keyword(s):

Failure Modes ◽

High Reliability ◽

Thickness Distribution ◽

Tube Hydroforming ◽

Forming Limit Diagram ◽

Plastic Instability ◽

Probabilistic Constraints ◽

Forming Limit ◽

Reliability Based Design ◽

Hydroforming Process

In metal forming processes, different parameters (Material constants, geometric dimensions, loads …) exhibits unavoidable scatter that lead the process unreliable and unstable. In this paper, we interest particularly in tube hydroforming process (THP). This process consists to apply an inner pressure combined to an axial displacement to manufacture the part. During the manufacturing phase, inappropriate choice of the loading paths can lead to failure. Deterministic approaches are unable to optimize the process with taking into account to the uncertainty. In this work, we introduce the Reliability-Based Design Optimization (RBDO) to optimize the process under probabilistic considerations to ensure a high reliability level and stability during the manufacturing phase and avoid the occurrence of such plastic instability. Taking account of the uncertainty offer to the process a high stability associated with a low probability of failure. The definition of the objective function and the probabilistic constraints takes advantages from the Forming Limit Diagram (FLD) and the Forming Limit Stress Diagram (FLSD) used as a failure criterion to detect the occurrence of wrinkling, severe thinning, and necking. A THP is then introduced as an example to illustrate the proposed approach. The results show the robustness and efficiency of RBDO to improve thickness distribution and minimize the risk of potential failure modes.

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