Papers by Keyword: Formability

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Authors: M. Loh-Mousavi, Kenichiro Mori, K. Hayashi, Seijiro Maki, M. Bakhshi
Abstract: The effect of oscillation of internal pressure on the formability and shape accuracy of the products in a pulsating hydroforming process of T-shaped parts was examined by finite element simulation. The local thinning was prevented by oscillating the internal pressure. The filling ratio of the die cavity and the symmetrical degree of the filling was increased by the oscillation of pressure. The calculated deforming shape and the wall thickness are in good agreement with the experimental ones. It was found that pulsating hydroforming is useful in improving the formability and shape accuracy in the T-shape hydroforming operation.
Authors: F.J. Avellaneda, Valentin Miguel-Eguía, Juana Coello, Alberto Martínez, Antonio Calatayud
Abstract: TRIP steels, or Transformed Induced Plasticity steels, have excellent mechanical properties if compared with conventional steels. The highlighted characteristic of these steels is that they modify the microstructure with the deformation process as part of the austenite transforms to martensite, with the consequent change of the material properties. One of the main problems of TRIP steels is strong elastic recovery, or springback, after forming. In this work, the springback phenomenon is evaluated by bending tests and the influence of the variables involved in it is determined. Experimental bending forces do not agree with theoretical predictions that are proposed in the literature. In spite of the bending radius having been considered an influence factor in the process, this work demonstrates that the aforementioned factor has a minor influence, at least for TRIP 800. The factor found to affect material recovery the most was the bending angle.
Authors: Khanh Dien Le, Tan Hung Nguyen, Ngoc Huy Tran, Thanh Son Le, Huy Bich Nguyen, Thanh Nam Nguyen
Abstract: Single Point Incremental Forming (SPIF) is a recent technology of forming sheet in several decades. Nowadays, SPIF technology is still continued to be studied, applied and ameliorated in sheet manufacturing in industry. However one of the difficulties of the technology is the forming angle is still small (smaller than 800 according the properties of metal sheets). This paper recommends a measure of increasing the plasticity of the sheet by heating in time of forming by SPIF technology. Naturally, the plasticity of metal sheet increases by the temperature of the material in forming process with its limitation and constraint. The paper represents the effect of heating metal sheet through the empirical process of SPIF technology directed by the design of experiment (DOE). The analyses of the results of experimental process is applied to show the effect of heating to the precision of Titanium sheet. Finally, some private opinions about the heating in SPIF are also mentioned as a very tiny contribution of the research for the new technology.
Authors: Mehmet Halkacı, Huseyin Selcuk Halkaci, Mevlut Turkoz, Behçet Dağhan
Abstract: Formability of sheet metals can be increased by Hydromechanical Deep Drawing (HDD) process. Formability of the deep drawn cups is generally assessed by Limiting Drawing Ratio (LDR) which is the ratio of the blank diameter to punch diameter. In order to increase LDR by HDD, process parameters of the HDD should be arranged properly. Arranging of the process parameters requires a great knowledge about the effects of the process parameters to certain performance criteria of the process. Determining of the effects of the process parameters by full factorial experiments is a hard duty. Hence certain statistical methods that decrease the number and the cost of the experiments and reduce the time should be used to find effective parameters and their appropriate levels. In this study orthogonal experimental array was applied and effective process parameters were determined by analyzing predicted data with Taguchi's robust parameter design method and ANOVA method. Then the results were compared with each other to evaluate differences between the methods. By using the appropriate levels of the parameters the LDR of AA 5754 aluminum alloy which uses in automotive industry intensely was determined.
Authors: Sung Won Youn, Kazumi Suda, Masaharu Takahashi, Ryutaro Maeda
Abstract: This study explores the dynamic mechanical properties (e.g., storage shear modulus, loss tangent and shear viscosity) and formability of a polyimide film by visco-elasticity measurement and hot-embossing tests. The variations of storage shear modulus, tangent delta and the shear viscosity were measured as a function of the temperature for two frequencies. As a polyimide goes through its glass transition, it exhibits dramatic decreases in shear modulus and viscosity as well as the peak of tangent delta, and continues to show strong dependence on frequency and temperature. Moreover, the filling characteristics (e.g., surface appearance, replicated depth and surface roughness) of polyimide were investigated by hot-embossing tests at different temperatures using a mold with an aspect ratio of 2.5:1.
Authors: Yun Kai Gao, Da Wei Gao, Yu Hang Gao
Abstract: A magnesium alloy substitution design for an automotive seat back frame is carried out. With the magnesium extrusion profiles and the stamping panel integrated, the weight of the seat back frame is reduced by 41.3% and the lightweight goal is achieved. At the same time, the magnesium alloy stamping panel is processed warm forming analysis and verified the formability of the magnesium alloy panel. Numerical calculations comparing the original structure and the substitution design are performed with finite element software, which ensured that the performance indicators such as the mode, the strength and the stiffness defined by related regulatory requirements are all realized. At last, a magnesium alloy substitution design has been proved to be successful.
Authors: Jong Hoon Yoon, Joon Tae Yoo, Kyung Ju Min, Ho Sung Lee
Abstract: It is well known that the significant weight reduction and increased strength have placed advanced aluminum-lithium alloys at the forefront of aerospace materials research. For example the use of aluminum-lithium based alloys for rocket fuel tank domes can reduce weight because aluminum-lithium alloys have lower density and higher strength than Al-Cu alloy 2219. However, Al-Li alloys have been shown the inherent low formability characteristic that make them susceptible to cracking during the spinning operations. In this study a novel heat treatment process on the formability of friction stir welded Al-Li alloy blanks are presented. It is shown that the successful heat treatment process has been developed with superior mechanical properties and currently the patent is applied.
Authors: Sang Beom Shin, Ha Geun Kim, Kyeong Gyu Kim
Abstract: The purpose of this study is to identify the principal factors controlling the formability of TMCP steel for curved hull plate. In order to do it, the initial residual stress in TMCP steel was evaluated using flatness measured in the flat bar cut by flame and analytical approach. Changes of the curved profiles in conventional steel and EH 36 TMCP steel of 50mm thick during cold bending and local heating were investigated using 3 dimensional measuring instruments. It was found that the formability in TMCP steel was mainly determined by the excessive distortion by the relaxation of residual stress during cold bending.
Authors: Pyung Su Kim, So Young Choi, Young Sik Kim, Jong Do Kim
Abstract: Bellows are widely used as parts in industrial machinery such as ships, valves, automotive, semiconductor equipment, flow and pressure sensors, and even in aircraft. Due to the recent depletion of conventional fossil fuels, natural liquified petroleum is increasingly demanded as an alternative energy, which in turn increases the demand for bellows on LNG ships. As the material used the bellows of LNG ships, the STS316L and INCOLOY 825 alloy, resistant to low-temperature embrittlement and corrosion, are used. STS316L is low-carbon stainless steel with a carbon content of less than 0.03%, preventing intergranular corrosion by welding work and maintaining its toughness and strength at a low temperature. In addition, Ni-Fe-Cr-based INCOLOY 825 alloy, containing Mo, Cu and Ti, is an alloy material resistant to general local corrosion in various atmospheres. INCOLOY 825 alloy is widely used for the creation of chemical processing equipment and in pollution-treatment facilities, oil and gas reduction equipment, acid manufacturing plants, pickling plants, nuclear fuel reprocessing and radioactive waste treatment facilities as well as in the bellows of LNG ships. Furthermore this material maintains good mechanical properties across a wide range of temperatures from ultra-low temperatures up to temperature approaching 500 °C. In this study, to assess its quality as a LNG ship bellows material, the STS316L and INCOLOY 825 alloy, used at an ultra-low temperature, the optimal welding conditions were established and its formability was analyzed by conducting an Erichsen test.
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