Improvement of hem quality by optimizing flanging and pre-hemming operations using computer aided die design

Livatyalı, Haydar; Muderrisoglu, A; Ahmetoglu, Mustafa A.; Akgerman, N.; Kinzel, Gary L.; Altan, Taylan

doi:10.1016/s0924-0136(99)00304-0

Cited by 64 publications

(38 citation statements)

References 2 publications

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“…The absence of horizontal movement of the blade prevents the risk of visual defects due to greater deflection of the outer part on the die [8]. The displacement velocity of the mobile plate is 5 mm.min −1 .…”

Section: Pre-hemmingmentioning

confidence: 99%

“…The load decrease is due to the flexion of the edge around the plastic hinge formed at the level of the flanging radius [7,8]. The length of the plateau, expressed through pre-hemming blade displacement, corresponds to the end of the first increase and the beginning of the second load increase.…”

Section: Pre-hemmingmentioning

confidence: 99%

“…Hemming is an assembly process by plastic deformation which consists of bending a small height of a sheet, called the outer part, over another, called the inner part [1]. This assembly method is widely used in the automotive industry for the opening parts of vehicles, to join the outer panel to the reinforcing inner part.…”

Section: Introductionmentioning

confidence: 99%

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A multi-step assembly process: drawing, flanging and hemming of metallic sheets

Manach

Maoût²,

Thuillier³

2010

EPJ Web of Conferences

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Abstract. This paper presents hemming tests on complex geometries, combining curved surfaces and radii of curvature in the plane. The samples are firstly prestrained in order to obtain a strain history prior to flanging and hemming. The choice of the sample geometries as well as prior plastic strains is based on a survey of current geometries hemmed in automotive doors. A device has been designed to hem these samples both by classical and roll-hemming processes and to allow a comparison between both technologies. Roll-in, which characterizes the change of geometry of the hemmed zone between flanging and hemming, and loads are obtained during this multistep process. Results show that roll-in observed in roll-hemming is lower than in classical hemming and that its evolution greatly differs between the two processes. The analysis of the results on different samples shows that it is difficult to establish rules on the variation of other parameters in such a complex multistep process and that it requires an intensive use of numerical simulation.

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Section: Pre-hemmingmentioning

confidence: 99%

Section: Pre-hemmingmentioning

confidence: 99%

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A multi-step assembly process: drawing, flanging and hemming of metallic sheets

Manach

Maoût²,

Thuillier³

2010

EPJ Web of Conferences

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“…Hemming is an assembly process by plastic strain which consists of bending the edge of one sheet, called the outer part, over the edge of another, called the inner part [1]. This assembly method is widely used in the automotive industry for thin sheets used for the opening parts of vehicles, such as doors, hoods, trunks, and sun roofs.…”

Section: Introductionmentioning

confidence: 99%

“…2 Illustration of (a) classical hemming and (b) roll-hemming allows for tests which are more easily done than what would be for non-planar surface samples due to the facilitated placement of the sheets in the tool. Furthermore, the plane strain hypothesis can be adopted for finite element modeling [1,[4][5][6]. Each type of geometry will generate different tensile and compressive states according to the orientation of the radii E sh/st and S sh/st compared to the flanging direction (Fig.…”

Section: Introductionmentioning

confidence: 99%

Classical and Roll-hemming Processes of Pre-strained Metallic Sheets

2009

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The goal of this investigation is to gather experimental data on the hemming of concave or convex edge-curved surface samples, to study the influence of geometry and pre-strain on roll-in and load, as well as to assess the validity of the numerical simulation of the process. A specific experimental set-up was designed to study classical and roll-hemming processes. The samples were pre-strained through biaxial tests to obtain a geometry and strain history similar to that of industrial parts. Flanging, pre-hemming, and hemming loads were recorded and geometrical measurements were taken after each step for the 6000 series aluminum alloy samples. It is shown that sample geometry influences both the roll-in and the load, though no clear relationship could be established. Results also show that the roll-in from roll-hemming is lower than from classical hemming and that its evolution greatly differs between the two processes. Tests on the different cases studied also indicate that classical hemming is more likely to cause damage.

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