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Tooling

Please find information, research projects and publications regarding cold forging tools in this section.

Tooling

Projects


    Publications

    • Kroiß, T.; Engel, U.; Merklein, M.: Comprehensive Approach for Process Modeling and Optimization in Cold Forging Considering Interactions between Process, Tool and Press. J. Mater. Process. Technol. 213(2012)7, 1118-1127                                                   
    • M. Milutinović, D. Movrin, T. Pepelnjak: Theoretical and experimental investigation of cold hobbing processes in cases of cone-like punch manufacturing. Int. j. adv. manuf. technol., 2012, vol. 58, iss. 9, pp 895-906                                                   

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    Tool design

    Projects

    • Microforming of bulk metal components from band material, Institute of Manufacturing Technology (LFT) Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany:

      The interest on mass production of small complex metal components is currently fostered by fields like electronics and micromechanics. A possible approach is seen in a multi-step bulk forming process, limited among scaling problems by handling difficulties between the forming stages. A radical simplification of the positioning of the workpiece is seen in a process in which a metal strip acts both as raw material and support of the workpiece through the different forming stages.  The results of these studies will lead up to a definition of the achievable geometries and a review of further one- and more step forming processes from the strip plane. The finite element simulation of different single step bulk forming processes has driven to the design of a working tool, which represents the experimental set-up for the study of both the single steps of the process and the entire forming chain. The combined analysis of simulation and experiments aims for an optimization of the metal flow during one and more step bulk forming processes. The study of the strip deformation and of different methods of material flow steering will be further conducted and deeper analyzed. In particular, a higher friction coefficient of the punch and a specific geometry of the blankholder are seen as possible solutions for a more effective extrusion process with minor consequences on the handling.

    • Thermal-tribological analysis and optimization, Institute for Production Engineering and Forming Machines (PtU) Technical University of Darmstadt, Germany:

      Having high forming rates in cold forging, a high amount of energy is converted into heat and the tool temperature rises. However, a constant tool temperature can only be achieved after numerous strokes. In order to investigate the thermal tribological conditions and the interactions, a project of three industrial companies and the PtU aims to develop a computer-aided process design for a thermal-tribological analysis of cold forging processes. Experiments on the Sliding Compression Test of the PtU are necessary to gain the knowledge to develop the model of the friction behavior. Therefore, the heating and cooling equipment of the Sliding Compression Test was optimized. Now, nearly unlimited specimen temperatures and tool temperatures up to 400°C are possible. Also, a software tool to simulate the stationary temperature was developed and integrated sensors in the tools of production processes measure the occurring temperatures. (Contact: Dipl.-Ing. Christoph Müller)

    Publications 

    • Liu T, Wang XQ, Chen XW. Precision forming process and die design of rocker shaft . Casting-Forging-Welding, 2012, 41(19): 88-91 (in Chinese).                                                   
    • Yan JM, Wang CY, Li W, et al. Influences of taper angle of punch on radial cold extrusion process of three-pillar universal joint pin. Forging & Stamping Technology, 2013, 38(2): 81-84.                                                   
    • Kroiß, T.; Engel, U.: Optimization of tool and process design for the cold forging of net-shape parts by simulation. In: Denkena, B.; Hollmann, F. (edtrs): Process Machine Interactions.Heidelberg, New York, London: Springer 2012. 419-438                                                   
    • V. Krušič, M. Fabjan: Design of product properties by suitable planning of a cold forging process. International conference on New Developments in Forging Technology, Institute for Metal Forming Technology, University of Stuttgart, June 2013, pp 171-180                                                     

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    Tool materials

    Projects

    • Experimental and analytical studies on the Ti-6Al-4V cold expanded fastener hole,  Northwestern Polytechnical University, China:

      The distribution of crack initiation life was determined by metallographic fracture data. Based on the crack growth formula,the equivalent initial flaw size which characterized the initial fatigue qualify was obtained by optimizing the reference crack size and the upper limit of equivalent initial flaw size. The rated equivalent initial flaw size was then determined. Referring to a designated economic repair size,the economic repair life with the reliability of 95% was obtained using the theory of probabilistic fracture mechanics.
    • Cold forging tool fatigue behaviour, the low cycle fatigue (LCF) behaviour of a Cr-Mo-V matrix-type high-speed steel (matrix-type HSS), The Institute of Forming Technology & Equipment (IFTE) of School of Materials Science and Engineering (SMSE) at Shanghai Jiao Tong University (SJTU), China:

      Strain-controlled fatigue tests were conducted under strain-controlled cyclic loading conditions with different axial strain amplitude levels at room temperature. The cyclic strain-stress relationship and the strain-life relationship were obtained.The fatigue damage process through the crack initiation and propagation was explained through observing the features of the fractures. Based on the core of evolutionary structural optimization(ESO) and considered the bulk metal forming features, a method-topology optimization method is proposed and adopted for preform design of bulk metal forming.

    Publications

    • Zhang Y, Hu CL, Zhao Z, et al. Low cycle fatigue behaviour of a Cr-Mo-V matrix-type high-speed steel used for cold forging. Materials and Design, 2013, 44: 612-621                                                   
    • She DS, Yue W, Fu ZQ, et al. The effect of nitriding temperature on hardness and microstructure of die steel pre-treated by ultrasonic cold forging technology. Materials & Design, 2013, 49: 392–399.                                                   
    • Andreas, K.; Noneder, J.; Engel, U.; Merklein, M.: Application of cemented carbide based forming tools in cold forging. In: Bouzakis, K.-D.; Bobzin, K.; Denkena, B.; Merklein, M. (Edt.): Proc. 10th International Conference THE "A" Coatings in Manufacturing Engineering, 2013, Aachen, 159-169                                                   
    • Andreas, K.; Merklein, M.; Engel, U.: Fatigue Behavior of Cemented Carbide Based Forming Tools. In: Proceedings of the 18th Plansee Seminar, 2013, Reutte, in print                                                  

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    Tool surfaces

    Projects

    • Ultrasonic cold forging technology (UCFT), China University of Geosciences (Beijing):

      To promote the formation and growth of nitride layer, a befitting surface nano-crystallization process was introduced as a pre-treatment of nitriding, and an optimized nitriding temperature was investigated. The diffusion of nitrogen and the formation of nitrides were markedly improved by UCFT pre-treatment. A thicker and harder nitrided layer was formed at a high nitriding temperature. It is an optimized process to be pre-treated by UCFT and nitriding at 520 °C for 4 h.
    • Fine Machining of Tool Surfaces, Institute of Manufacturing Technology (LFT) Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany:


      Due to the high stresses in cold forging high speed steels (HSS) and cemented carbides (CC) are often used as tool materials. In many cases complex tool geometries are hard machined by electrical discharge machining (EDM). For improvement of surface properties the white layer caused by EDM is usually removed by cost intensive polishing. For reduction of polishing effort as well as for improvement of ED machined surfaces different post machining methods after EDM are available. In this project the fatigue behavior of tools made of HSS and CC manufactured by the process chain “EDM - post machining - polishing” is investigated. Aim of the project is to derive requirements and recommendations from the gained correlations between tool manufacturing, surface properties and fatigue behavior for an optimized tool production.

    Publications:

    • Andreas, K.; Merklein, M.; Engel, U.: Werkzeugherstellung in der Kaltmassivumformung - Einfluss der Werkzeugoberfläche auf die tribologischen Bedingungen. wt Werkstattstechnik online, 10(2012), 672-677                                                   
    • Andreas, K.; Merklein, M.; Engel, U.: Influence of Combined Hard and Fine Machining on the Surface Properties of Cemented Carbides. Tribology in Industry, 34(2012)3, 119-127                                                   

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    Tool coatings

    Projects

    • MARS - Self lubricating materials for automotive industry, Italy:

      The project that involves 8 industrial partners, 2 universities and 1 research centre is starting in 2011 (duration of 3 years). The objective of the project is the development of new lubricants and new coatings based on nano-technologies to reduce friction and wear in extruded components for automation industries.

    Publications

    • Schrader, T.; Engel, U.; Geiger, M.; Merklein, M.: Mehrlagenbeschichtungen für den beanspruchungsgerechten Einsatz bei Kaltmassivumformwerkzeugen. In: Faulstich, M.; Geiger, M.; Kukla, H.; Wolf, G. (Edt.): Moderne Beschichtungen zum Verschleißschutz von Werkzeugen, 2012, Sulzbach-Rosenberg: DORNER PrintConcept, 181-208                                                 

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    Prestressing

    Projects

    Publications

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