Recent developments in hydroforming technology

Siegert, K.; Häussermann, M.; Lösch, Bruno; Rieger, R.

doi:10.1016/s0924-0136(99)00206-x

Cited by 86 publications

(42 citation statements)

References 1 publication

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“…To adapt a stress condition which represents a typical combination of deep drawing and stretch forming [20], the diameter of the initial blank is expanded in order to constrain the material flow due to compression stresses in the flange. The initial dimensions of the elliptical blank are defined to 315 mm×359 mm.…”

Section: Experimental Geometrymentioning

confidence: 99%

Variation of deep drawing steel grades’ properties in dependency of the stress state and its impact on FEA

Goedel

Merklein

2011

Int J Mater Form

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In industrial sheet metal forming processes the complexity of parts has been increased within the last decade due to the demands on ambitious designs and lightweight construction. As the forming processes are often laid out near the limit of feasibility, small variations of process parameters and materials' properties may lead to an increased scrap rate in serial production. The consideration of varying parameters in the computerized process design is generally realizable, but especially the modelling of the material properties' variation in numerical simulation close to reality is not investigated comprehensively yet. The varying parameters considered in a so called stochastic simulation are often limited to the mechanical properties, which can be determined within the uniaxial tensile test. As within the forming process of a complex sheet metal part different stress states occur, the batch variation under different forming conditions has to be investigated in detail. Within this work a basic investigation for the consideration of the batch variation under different stress states is presented. Three coils of the same steel grade, the mild deep drawing steel DX56, are characterised experimentally in order to investigate the scatter band of the stresses between the three batches representing material variation close to reality. For this the flow behaviour is determined under uniaxial stress condition and under biaxial stress condition. Furthermore the results of the tests under biaxial stress condition lead to a batch specific biax-stress-point, which represents a further reference point for the yield locus interpolation according to Hill 90. The forming limit diagrams are determined experimentally for the three batches in order to reproduce scattering of the onset of necking as well. Based on the experimental results, three batch specific material models for FE-simulation are prepared and used as input parameters for numerical forming simulations. Using the cross die geometry with two different initial blank geometries, different stress states can be adjusted in four reference points, covering the stress states between uniaxial and biaxial stress condition, thus, the plane strain area. Within the reference points, the effect of materials' properties variation on the risk of failure is evaluated.

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Section: Experimental Geometrymentioning

confidence: 99%

Variation of deep drawing steel grades’ properties in dependency of the stress state and its impact on FEA

Goedel

Merklein

2011

Int J Mater Form

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“…With this system, retrogressive, constant, and progressive blank holding force trajectories were pre-determined using special software. Today, modern drawing presses have hydraulic blank holders that are usually installed in the press table as die cushions that build up the BHF through the blank holders [6][7][8][9]. Hydraulic cushions with proportional or servo valves that are used to achieve accuracy in BHF control in press systems have proven to be effective.…”

Section: Introductionmentioning

confidence: 99%

A study of the control of the blank holding force using an MR damper in a drawing press

2010

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The predominant failure modes (wrinkling and tearing) must be avoided during the drawing process in sheet metal forming. These defects may be eliminated by using a controllable device for which the blank holding force (BHF) is adjustable. The purpose of this research is to verify the possibility of using a magneto-rheological (MR) damper for obtaining an almost constant BHF in drawing presses. The damper force is controlled by adjusting the current that is applied to the MR fluid, which is a functional material. To realize this aim, a prototypical press system is manufactured. A control test using a closed-loop PID controller is carried out for achieving the objective where by a constant BHF is retained at a constant prescribed force, while the press slide translates at a constant velocity. The results show that the BHF of the drawing press can be controlled effectively by using the proposed MR damper.

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“…For this reason authors have dedicated a specific analysis phase where an implicit solver is used to define the best design for ABSTRACT: Sheet Hydroforming is considered a good opportunity when it is necessary to deal with complex shapes. However, it is common knowledge that it is quite difficult to control such a kind of technology because of an appropriate press tooling is necessary and the press tooling supplier is often the technology supplier for the given problem [1]. Within a larger research program it is demonstrated that it is possible to use traditional hydraulic press tooling having the chance to manage a high level of process variables thanks to the development of a dedicated forming tool named hydroforming cell.…”

Section: Introductionmentioning

confidence: 99%

Computer Aided Simulation as valid tool for sheet hydroforming process development

et al. 2008

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Recent developments in hydroforming technology

Cited by 86 publications

References 1 publication

Variation of deep drawing steel grades’ properties in dependency of the stress state and its impact on FEA

Variation of deep drawing steel grades’ properties in dependency of the stress state and its impact on FEA

A study of the control of the blank holding force using an MR damper in a drawing press

Computer Aided Simulation as valid tool for sheet hydroforming process development

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