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

High speed joining process by laser shock forming for the micro range

The importance to implement more functionality on the same space pushes miniaturization and makes hybrid joints under various conditions, also in the micro range, necessary. Conventional joining processes, which are used in macro range, cannot be easily transferred to micro range dimensions. In this work a new high speed joining method for the micro range is presented, which is realized by a plastic forming process based on TEA-CO2-Laser induced shockwaves. In a first step it is shown how sheet-sheet joints can be realized with this method. The experimental results illustrate the possibilities as well as the limits of the joining process by laser shock forming. Also the possible defects which can occur during the joining process are presented. Especially fracture of material at the edge. This is explained by the sharp edges in the joining area, which are caused by the production process of the specimen

超高圧を利用したマイクロ逐次シートハイドロフォーミングに関する研究

首都大学東京, 2016-03-25, 博士（工学）, 甲第580号首都大学東

Kolloquium Mikroproduktion und Abschlusskolloquium SFB 499 ; 11. - 12. Oktober 2011, Karlsruhe (KIT Scientific Reports ; 7591)

In diesem Tagungsband werden aktuelle Ergebnisse der angewandten Grundlagenforschung auf dem Gebiet der Mikroproduktion vorgestellt. Die dargestellten Arbeiten und Ergebnisse stammen vom SFB 499 "Mikrourformen", dem SFB 747 "Mikrokaltumformen", der FOR 702 "Maschinen-, Werkzeug- und Prozessentwicklung für neue Verfahren zur Herstellung von Mikrobauteilen über flüssige Phasen" und aus dem Umfeld des 2010 abgeschlossenen SFB 516 "Konstruktion und Fertigung aktiver Mikrosysteme"

Process analysis and design in micro deep drawing utilizing a flexible die

As a result of the remarkable demands on electronic and other portable compact devices, the need to produce various miniaturized parts, particularly those made from metallic sheet is growing. In other words, in order for manufacturing companies to stay in competition, they are required to develop new and innovative fabricating processes to produce micro components with more complex features and a high standard of quality and functionality. Microforming is a micro fabrication process that can be employed efficiently for mass production with the advantages of greatly minimizing material waste and producing highly accurate product geometry. However, since the clearance between the rigid tools, i.e. punch and die, utilized in microforming techniques is relatively very small, there is a high risk of damaging the tools during the forming operations. Therefore, the use of forming tools made of flexible materials in sheet metal forming processes at micro scale has powerful potential advantages. The main advantages include a reduction in the production cost, eliminating the alignment and mismatch difficulties, and also the creation of parts with different geometrical shapes using the same flexible tool. As the workpiece is in contact with a flexible surface, this process can significantly improve the quality of the obtained products. Despite these clear advantages, micro flexible forming techniques are currently only utilized in very limited industrial applications. One reason for this is that the deformation behaviour and failure mode of sheet metals formed at micro scale are not yet well understood. Additionally, the experience-based knowledge of the micro-forming process parameters is not sufficient, particularly when flexible tools are used. Hence, to advance this technology and to improve the production quality of formed micro parts, more investigation of the key process parameters related to the material deformation are needed. The main contribution of this work is the development of a novel technique for achieving micro deep drawing of stainless steel 304 sheets using a flexible die and where an initial gap (positive or negative) is adopted between the blank holder plate and an adjustment ring utilized in the size-scaled forming systems developed for this purpose. The interesting point here is that this study presents the first attempt of employing flexible material as a forming die tool in the micro deep drawing technology to produce micro metallic cups at different scaling levels. Polyurethane rubber materials are employed in this study for the forming flexible die with various Shore A hardness. Also, the stainless steel 304 sheets utilized for the workpieces have different initial thicknesses. Various parameters that have a significant influence on the sheet formability at micro scale are carefully considered, these include initial gap value, rubber material properties, initial blank thickness, initial blank diameter, friction coefficients at various contact interfaces, diameter and height of the rubber die and process scaling factor. The size effect category of process dimension was also taken into account using similarity theory. Three size-scaled micro deep drawing systems were developed correspondingly to three different scaling factors. In each case, finite element simulations for the intended micro drawing systems are performed with the aim of identifying optimum conditions for the novel forming methodology presented in this thesis. The numerical models are built using the known commercial code Abaqus/Standard. To verify the microforming methodology adopted for the proposal technique as well as to validate the predictions obtained from simulations, an appropriate number of micro deep drawing experiments are conducted. This is achieved using a special experimental set up, designed and manufactured to fulfil the various requirements of the micro-forming process design procedure. The new knowledge provided by this work provides, for the first time, a predictive capability for micro deep drawing using flexible tools that in turn could lead to a commercially viable production scale process

ICHSF2014

Since the first ICHSF, which was held in 2004 at the Technische Universität Dortmund, Germany, this biannual conference has grown into one of the major events for high speed forming technologies and its applications. This meeting series is now being organized with the support of the International Impulse Forming Group (I2FG) that was formed in October 2008 through the vision of Professor Erman Tekkaya. His goal was to model this in many ways after the International Cold Forging Research Group which has been instrumental in applying cold forging to wide manufacturing practice. The public face of this site can be found at http://www.i2fg.org with useful information as well as the proceedings of all the ICHSF meetings. This 6th conference is organized as a joint event of the Department of Mechanical Engineering of KAIST (Korea Advanced Institute of Science and Technology) and the Institute of Forming Technology and Lightweight Construction of Technische Universität Dortmund