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A4 - Incremental Forming



Fundamental Research and Process Development for the Manufacturing of Load-Optimized Parts by Incremental Sheet-Bulk Metal Forming

Project Status: Active

Last Update: 31.07.2019



Members


The superordinate aim in the subproject (SP) A4 is the flexible production of near net shaped and load-adjusted functional components by means of incremental sheet bulk metal forming (ISBMF). In the second funding period the investigation applied the aforementioned technology to describe and control the material flow. This was acomplished by conducting analytical, numerical and experimental investigations. The identified mechanisms of action thus form an efficient instrument for the geometrical component gradation. Using the principle of stress superposition, it was found out the process forces could be reduced by up to 30%. However, in the case of high-strength materials - despite the force reduction - the tool-loads occurring during the final calibration step reduce the tool-lifetime. Nevertheless, a successful calibration step is imperative to reach the required dimensional tolerances. This underlines the need for further strategies for a reduction of the tool loads. To improve the precision of the functional elements after forming three approaches have been developed and tested:

  • Geometrical adjustment of the initial sheet geometry
  • Adjustment of the process including a pre-forming step
  • Modification of the tool surface using bionical structures (cooperation with SP B2 and SP B5)

In addition to a further reduction of the process forces, the grading of the components mechanical properties represents the superior aim in the third period. The intention is to increase both the lifetime of the workpiece and the tool. Reaching this aim means to answer the following scientific questions:

 

1. The process strategies developed in the second period allow to manufacture parts with an identical geometry but different strain distribution.

→ Central question WP1: Which maximum strength and its distribution can be reached by a variation of the strain route?

 → Current State WP1: The numerical investigation on the process kinematics present a deviation of the effective plastic strain by Δφmax = 58%. Related to the total effective plastic strain this signifies a changed yield stress of ΔYf = 20%. The different subsequent gear forming processes lead to a further grading of the effective plastic strain and its distribution.


2. The combined forming of multiple layered sheets with different material properties to hybrid components was tested in the second funding period.

→ Central question WP2: How does the forming of hybrid components influence the material flow, the forming forces and the of grading the mechanical properties of the functional elements?

→ Current State WP2: The investigation on the hybridization of functional components presents an influence on the material flow corresponding to the changed sheet thickness Δt due to a thinner steel blank. This leads to a locally increased effective plastic strain Δφmax. Thus, an improved grading of the strength as well as an enhanced lightweight potential could already be shown.

 

 

3. In previous tests the use of an electrical current through the forming region during the forming process has shown a temporary decrease of the forming force of around 20%.

Central question WP3: What maximum force reduction can be achieved, using an electrical current through the forming region without a significant reduction of the strain hardening.

 

The strain route controlled strain hardening as well as the use of hybrid components allow adaption of the component's mechanical properties to the stress collective occurring during the later use. However, in the case of tools, strenght strength enhancement through alternative material selection or conditioning is almost exhausted. Therefore, adjustment of the stress collective to the given stress limits must take place. In addition to the use of an electrical current during the forming process, the use of hybrid components gives a further approach to reduce the tool load. An overview of the research content for the third funding period is shown below.

 

 Aims and methods of the subproject A4 during the third period

 


Working Groups


Publications

    2019

    • Wernicke, S.; Gies, S.; Tekkaya, A.: Manufacturing of Hybrid Gears by Incremental Sheet-Bulk Metal Forming. In: Procedia Manufacturing, Volume 27, Pages 152-157 (Edt.): (2019), ELSEVIER, published

    2018

    • Sieczkarek, P.; Wernicke, S.; Gies, S.; Tekkaya, A.: Inkrementelle Blechmassivumformung. In: wt Werkstattstechnik online (Edt.): 10(2018), Düsseldorf: Springer-VDI-Verlag GmbH & Co. KG, pp. 679-685

    2017

    • Wernicke, S.; Sieczkarek, P.; Gies, S.; Tekkaya, A.: Vorrichtung und Verfahren zur Randaufdickung eines Werkstückes. In: Deutsche Patentanmeldung - Aktenzeichen: DE 10 2017 011 441 (Edt.): (2017), submitted
    • Sieczkarek, P.; Wernicke, S.; Gies, S.; Tekkaya, A.; Krebs, E.; Wiederkehr, P.; Biermann, D.; Tillmann, W.; Stangier, D.: Improvement strategies for the formfilling in incremental gear forming processes. In: Production Engineering, 11(2017)6, pp. 623-631
    • Sieczkarek, P.; Wernicke, S.; Gies, S.; Tekkaya, A.: Incremental Sheet-Bulk Metal Forming - Overview on the development of a new forming technology. In: 50th ICFG Plenary Meeting, 3-6 September 2017, Shanghai, China, (2017), published
    • Wernicke, S.; Gies, S.; Tekkaya, A.; Ben Khalifa, N.: Herstellung Von Belastungsangepassten Funktionsbauteilen Mittels Inkrementeller Blechmassivumformung. In: 22. Umformtechnisches Kolloquium Hannover – Innovationspotentiale in der Umformtechnik (Edt.): (2017), published

    Presentations

      2018

      • 07.11.2018: Wernicke, S.; Gies, S.; Tekkaya, A.: Herstellung hybrider Zahnräder durch inkrementelle Blechmassivumformung, ICAFT/SFU/AutoMetForm 2018, Chemnitz