Improved Formability by Control of Strain Distribution in Sheet Stamping Using Electromagnetic Impulses

Daehn, G. S.; Shang, J.; Vohnout, V. J.

Improved Formability by Control of Strain Distribution in Sheet Stamping Using Electromagnetic Impulses

dc.contributor.author	Daehn, G. S.	de
dc.contributor.author	Shang, J.	de
dc.contributor.author	Vohnout, V. J.	de
dc.date.accessioned	2010-04-08T08:37:03Z
dc.date.available	2010-04-08T08:37:03Z
dc.date.issued	2004	de
dc.description.abstract	Stamping failures consist of, broadly speaking, either tearing (excessive local strain energy) or wrinkling (insufficient or inappropriate local strain energy). Good parts are produced when the strain energy or plastic work is effectively distributed during the forming process such that tears and wrinkles are eliminated. The process window framed by tearing and wrinkling limits can be rather small for some materials, notably aluminum alloys. At present, there are no established methods of directly controlling the forming energy distribution within the tool during a stamping operation. All current commercial methods attempt plastic strain control at the sheet boundary by various binder geometries and pressure profiles. While improvements by active control of draw beads and binder pressure have led to improved stamping performance, these methods still broadly rely on tool geometry to set the energy distribution. We have recently developed and demonstrated a method for more directly controlling the distribution of forming energy in a stamping operation based on an extension of electromagnetic (EM) impulse forming. We now have techniques for embedding and operating EM pulse actuator coils in stamping tools. These coils can be operated in a single high power pulse or as a series of lower energy pulses occurring several times during the forming stroke. A single high power pulse can provide the advantage of increased material forming limits of high velocity forming. However, applying a series of lower power pulses can increase forming limits without exposing the tooling and coil to large shock loads. Multiple pulses reduce the maximum strain levels by engaging more of the part material in the forming process which mimics (eliminates) the use of lubricants. Conventional production stamping rates are technically obtainable with proper integration of the EM impulse circuit with the forming press and tooling. This paper focuses on the basic design approach of our multiple pulse technique and integrated process forming results. Comparisons to other augmented stamping processes as well as conventional stamping are presented in terms of both simple metrics, such as draw depth and strain distributions.	en
dc.identifier.uri	http://hdl.handle.net/2003/27036
dc.identifier.uri	http://dx.doi.org/10.17877/DE290R-8195
dc.language.iso	en	de
dc.publisher	Institut für Umformtechnik - Technische Universität Dortmund	de
dc.relation.ispartof	1st International Conference on High Speed Forming, March 31, April 1, 2004, Dortmund, Germany	de
dc.subject	aluminium	en
dc.subject	deep drawing	en
dc.subject	electro-impulse	en
dc.subject.ddc	620	de
dc.subject.ddc	670	de
dc.title	Improved Formability by Control of Strain Distribution in Sheet Stamping Using Electromagnetic Impulses	en
dc.type	Text	de
dc.type.publicationtype	conferenceObject	de
dcterms.accessRights	open access

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