Le frottement en emboutissage :

Interactions entre tôle, outil et lubrifiant

Friction in sheet metal stamping :

Interactions sheet/tool/lubricant

¹ C.R.M., Service Application des Métaux, Liège (Belgique)
² RNUR, Direction de la Recherche, Boulogne-Billancourt

Abstract

This paper is mainly focused on the sheet, tool and lubricant characteristics that largely affect the friction coefficient in stamping operations. As a matter of introduction, the simulative tests used in this research are briefly described. Then, the extremely important role of the sheet and tool roughness is underlined and the way these factors act on the lubrication regime during press forming is highlighted. The lubricant is taken into account by means of the viscosity and the amount of oil present on the sheet. Finally, a theoretical model adapted from the Stribeck curve is developed as a basis for the implementation of a general friction algorithm in the FF.M codes.

A second part is related to the evaluation of the tool material effect on galling. A methodology, based on laboratory simulative tests backed-up by industrial trials allows to derive practical rules to better control the frictional conditions and avoid galling.