Systematic investigation of geometrical parameters’ influence on the appearance of surface deflections in sheet metal forming

Weinschenk, A.; Volk, Wolfram

doi:10.1088/1742-6596/734/3/032004

Cited by 3 publications

(2 citation statements)

References 5 publications

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“…Given the fact that friction is a key parameter for the robustness of the deep drawing process [1], the tribological behavior in the forming process must be fully understood and implemented in Finite-Element (FE)-supported tool development. However, the most common constant coefficient of friction (COF) is used and serves often as an additional fitting parameter between numerical simulation and experiment, resulting in a variation of the COF from 0.05 [2] to 0.15 [3]. To integrate more realistic, non-constant friction models into the forming simulation, several approaches have been adopted to provide the describing data.…”

Section: Introductionmentioning

confidence: 99%

Influence of Test Stand and Contact Size Sensitivity on the Friction Coefficient in Sheet Metal Forming

2018

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The precise knowledge of frictional behavior is highly relevant for accurate modelling in sheet metal forming simulations. This allows e.g., the precise prediction of restraining forces which, in turn, determines an optimal draw bead strategy and blank-texture-development for automotive components. As a result, tryout loops can be avoided and thus production costs can be reduced. Nevertheless, the benefit of this detailed friction description is often ignored by the use of a constant friction coefficient. Finding a practical solution has motivated numerous research projects in recent decades. In this context, many efforts have been made to develop test stands to gain a better understanding of friction and to determine load-dependent friction coefficients for simulations. However, different test stands for friction investigation show a big quantitative difference in friction value which makes the direct use of the values in finite element simulation questionable. Therefore, the focus of this paper is to compare two different common strip drawing tests and detect the sources of deviation. In particular, the influence of the contact area between tool and blank is investigated. The results indicate that while the effect of the different test stands is negligible, a high dependency of the friction coefficient on the contact area was shown. This phenomenon is caused by macroscopic lubricant distribution over the contact area, which varies according to the size of the tools. The results show a potential field of research in categorizing different friction test stands and resolving the issue of quantitative non-comparable coefficients of friction.

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Section: Introductionmentioning

confidence: 99%

Influence of Test Stand and Contact Size Sensitivity on the Friction Coefficient in Sheet Metal Forming

2018

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“…This is repeated until the part no longer has any more surface deflections. An earlier study analyzed the influence of geometrical parameters of a sheet metal part with a door handle depression on the surface deflection depth [3]. It showed that an increase of the part's global curvature reduces depth significantly.…”

Section: Objective and Approachmentioning

confidence: 99%

Strategy to prevent surface deflections for automotive sheet metal parts

Weinschenk

Volk

2017

J. Phys.: Conf. Ser.

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A study on springback of bending linear flow split profiles P Mahajan, C Taplick, M Özel et al. Abstract. Surface deflections are undesirable in automotive outer panels because they disturb their visual appearance. As a consequence, the geometry of the deep drawing tool is manually adjusted during tryout until the produced parts do not display any surface deflections. The aim of this paper is to reduce this time-consuming and cost-intensive tryout by slightly changing the geometry of the tool in an early state of the product development process to lower the risk of surface deflections. Therefore, this paper shows the influence of geometrical parameters of the deep drawing tool on the occurrence of surface deflections. A multiple curved outer panel with a door handle depression is chosen for the investigation. Typically, so-called "teddy bear ears" occur around the depression. The sheet metal material AA6016 with a sheet thickness of 1.0 mm is used. Numerical simulations of the draw operation and springback are performed in AutoForm. An analysis of the curvature before and after springback is used to detect surface deflections. The influence of the stresses and curvatures on the appearance of surface deflections is analyzed. For the experimental validation, stoning is used to detect surface deflections on a physical part. A very good agreement between the numerical and experimental results was obtained. The results show that the existence of surface deflections strongly depends on the initial curvature of the part and the appearance depends on the distribution of minor stresses. It is possible to reduce the risk of surface deflections during the design phase by changing the geometry.

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Sheet metal shrink flanging process: a critical review of current scenario and future prospects

Dewang¹,

Sharma

2023

Materials and Manufacturing Processes

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Systematic investigation of geometrical parameters’ influence on the appearance of surface deflections in sheet metal forming

Cited by 3 publications

References 5 publications

Influence of Test Stand and Contact Size Sensitivity on the Friction Coefficient in Sheet Metal Forming

Influence of Test Stand and Contact Size Sensitivity on the Friction Coefficient in Sheet Metal Forming

Strategy to prevent surface deflections for automotive sheet metal parts

Sheet metal shrink flanging process: a critical review of current scenario and future prospects

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