Papers by Keyword: Cold Forming

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Authors: J. Jeswiet
Abstract: The use of computers in manufacturing has enabled the development of several new sheet metal forming processes. This paper describes modifications that have been made to traditional forming methods such as conventional spinning and shear forming, where deformation is localized. Recent advances have enabled this localized deformation to be accurately controlled and studied. Current developments have been focused on forming asymmetric parts using CNC technology, without the need for costly dies. Asymmetric Incremental Forming has the potential to revolutionize sheet metal forming, making it accessible to all levels of manufacturing.
Authors: Ulf Engel, Emil Egerer
Authors: E.S. Reshetnikova, D.U. Usatiy, T.V. Usataya
Abstract: The urgency of a new process development of cold forming of high-strength flange bolts has been shown in the article. It also points out some shortcomings of existing technologies. To improve the quality of bolts a new instrument design was developed. The research of the working tool identification impact on its resistance and stress-strain state of the workpiece was carry out. The software package DEFORM, designed for process simulation of metal forming is used in the article. The mathematical and computer modeling technology bolt stamping with flange was applied to carry out the study. Based on the conducted theoretical and experimental studies a new technology for manufacturing the flange bolts is patented.
Authors: Lucie Páleníková, Lenka Klakurková, Pavel Gejdoš, Michaela Remešová, Martin Juliš, Ladislav Čelko
Abstract: In this article, the causes of damage of a cover were investigated by metallographic and fractographic analysis. The component part was made from non-alloy quality steel for cold forming DC04. The failure occurred during high temperature pulsation (90 °C, 7b, 1 Hz) after 180,000 cycles. This component part was fabricated by deep drawing. After this process’s step, outlets were soldered at 1100 °C/5 min. to this part and then whole component part was coated using method without any specification. The coating layer was formed of Zn-Ni. The last step in this process was hemming where all component parts were assembled together. This case study was solved using light and scanning electron microscopy. The chemical composition was detected by energy dispersive X-ray analysis.
Authors: Minoru Yamashita, Toshio Hattori, Koji Kuwahara
Abstract: In order to accomplish the circular cup drawing of the sheet material whose ductility is extremely poor under the cold forming condition, the Maslennikov's technique was applied. A deformable rubber ring was used instead of the hard punch. Test material was magnesium alloy AZ31-O sheet. Small die profile radius was applied, which was twice or 4 times of the sheet thickness. A semisolid lubricant was used for the lubrication of the blank - die interface, on the other hand, the rubber - blank interface was degreased to increase friction. The limiting drawing ratio of 1.31 was attained. A peculiar fracture mode arises, where the material suddenly fractured with crack evolution emanating from the flange periphery. The fracture strain is found approximately equal to the work hardening exponent n-value in plastic property. Another kind of crack arose in the circumferential direction of the cup during unbending process with smaller die profile radius. To decrease the scratched lines of the cup surface caused by very high sliding contact pressure to the die, high-speed drawing was tested using a drop-weight. The surface was improved, because the material - tool contact was successfully prevented by the hydrodynamic lubrication film.
Authors: Kuang-Jau Fann, Pao Min Huang
Abstract: Because of being in possession of shape memory effect and superelasticity, Ni-Ti shape memory alloys have earned more intense gaze on the next generation applications. Conventionally, Ni-Ti shape memory alloys are manufactured by hot forming and constraint aging, which need a capital-intensive investment. To have a cost benefit getting rid of plenty of die sets, this study is aimed to form Ni-Ti shape memory alloys at room temperature and to age them at elevated temperature without any die sets. In this study, starting with solution treatments at various temperatures, which served as annealing process, Ni-rich Ni-Ti shape memory alloy wires were bent by V-shaped punches in different curvatures at room temperature. Subsequently, the wires were aged at different temperatures to have shape memory effect. As a result, springback was found after withdrawing the bending punch and further after the aging treatment as well. A higher solution treatment temperature or a smaller bending radius leads to a smaller springback, while a higher aging treatment temperature made a larger springback. This springback may be compensated by bending the wires in further larger curvatures to keep the shape accuracy as designed. To explore the shape memory effect, a reverse bending test was performed. It shows that all bent wires after aging had a shape recovery rate above 96.3% on average.
Authors: B. Dodd, Y. Le Petitcorps
Authors: Iwona Pokorska
Abstract: This paper has been focused on presentation of application of computer methods in design and identification of PM materials in cold forming operations. The solutions for direct and inverse problems of powder forging have been described. In order to solve an identification problem for powder metallurgy materials we assume desired material model characterizing by specific material law with desired material parameters. The material parameters are the design variables of the optimization problem which have to be solved.
Authors: Adam Szurdak, Gerhard Hirt
Abstract: Micro lubrication pockets decrease the frictional losses and improve the wear resistance of lubricated machine elements. Depending on the application, the pocket dimension and the area density (ratio of the projected pocket area to the non-textured area) must be optimized. Otherwise, the lubrication pockets might increase friction and wear. Besides the determination of the optimized texture, the production process needs to manufacture the pockets with high reproducibility and accuracy, since each deviation of the texture might reduce the improvement of the tribological properties. The goal of this work is to develop a new forming setup capable of decreasing the influence of deviations in the material, of the tool or due to a process inaccuracy ́s. Therefore, a roller-coining process based on a pneumatic system was developed to keep the forming force and thus the pocket dimension constant. This setup was as well used to texture the roller, since the manufacturing of a prominent micro texture on a curved surface with high tolerances is a difficult task for other texturing methods. The experimental verification of the setup showed that by using the pneumatic setup the standard deviation of the pocket depth was reduced by an average factor of 1.9.
Authors: Marius Herrmann, Bernd Kuhfuss, Christian Schenck
Abstract: Rotary swaging is an incremental cold forming process for tubes and rods. The established processes use lubricants based on mineral oil. The functions of the lubricant are the reduction of friction, wear and tool load, furthermore it cools the tools and flushes the working zone. But the use of lubricant increases the cost due to additional process steps and lubricant is diverted with the work piece during the process. Thus from economic and ecological points of view it is worthwhile to eliminate the use of lubricant. Therefore it is necessary to realize the functions of the lubricant in another way. For example by means of coating and micro-structuring of the tools the friction and wear can be influenced. In this study dry rotary swaging is tested with conventional tools and machine settings. The analysis of the recorded process parameters and the formed geometry of the workpiece reveal the potential of dry rotary swaging, but also the difficulties that arise. Dry rotary swaging needs a modification of the process and system parameters as well as an adjustment of the tools.
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