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Contact pressure evolution and its relation to wear in sheet metal forming

journal contribution
posted on 2008-11-26, 00:00 authored by Michael PereiraMichael Pereira, W Yan, Bernard RolfeBernard Rolfe
For a given sheet metal forming process, an accurate determination of the contact pressure distribution is an essential step towards the estimation of tool life. This investigation utilizes finite element (FE) analysis to model and explain the evolution and distribution of contact pressure over the die radius, throughout the duration of a channel forming process. It was found that a typical two-peak steady-state contact pressure response exists for the majority of the process. However, this was preceded by an initial transient response, characterized by extremely large and localized contact pressures, which were more than double the magnitude of the steady-state peak pressure. The validity of the predicted contact pressure behavior was assessed via detailed numerical analysis and by examining the wear response of an experimental stamping operation. The experimental results revealed that the high contact pressure zones of the transient response corresponded to a severe galling wear mechanism. Therefore, the transient response may be of primary significance to the tool wear response; thus questioning the applicability of traditional bending-under-tension wear tests for sheet metal stamping processes. Finally, a parametric study was conducted, examining the influence of the major process parameters on the steady-state and peak transient contact pressures, using the developed FE model. It was found that the bend ratio and the blank material ultimate tensile strength had the most influence on the peak contact pressures. The main process-related parameters, friction coefficient and blank holder force, were found to have only a minor influence.

History

Journal

Wear

Volume

265

Issue

11-12

Pagination

1687 - 1699

Publisher

Elsevier B.V.

Location

Amsterdam, The Netherlands

ISSN

0043-1648

eISSN

1873-2577

Language

eng

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

2008, Elsevier B.V.