8/13/2019 On the Effect of the Orientation of Sheet Rolling Direction in Shot Peen Forming

1/2

On the effect of the orientation of sheet rolling direction in shot peen forming

A. Garipy, S. Larose, C. Perron, P. Bocher, M. Lvesque

Journal of Materials Processing Technology 06/2013; 213(6):926938.

DOI:10.1016/j.jmatprotec.2013.01.003

ABSTRACT Peen forming is commonly used in the aerospace industry to shape large and thin panels,

such as wing skins. This manufacturing process uses shot peening to introduce unbalanced compressive

stresses near the surface of the component. These stresses tend to bend the panel and, whenoptimized, lead to the desired contour. Sheet materials often exhibit both elastic and plastic anisotropy,

which can alter the development of curvatures. Since peen forming relies on compressive stresses to

upset equilibrium, resulting curvatures may also be affected by initial stresses in the part. In this work,

the influence of the rolling direction orientation with respect to the sample was investigated

experimentally and numerically for the first time for aluminium alloy 2024-T3 specimens. Although

maximum deflections were only slightly dependent on the rolling direction orientation, it was found that

radii of curvature varied by as much as 10% with respect to this parameter. Finite element simulations

allowed quantification of the individual effects of non-equibiaxial initial stresses and elastic orthotropy.

It was found that these factors can significantly influence curvature development. Comparison of

experimental and numerical results suggested that plastic anisotropy should also be taken into accountin future studies. The tools developed in this study show promises for the accurate prediction of peen

forming process for large scale components.

Effects of Rolling Direction and Lubricant on Friction in Sheet Metal Forming

Lubrication and friction at workpiece-tool interface play an important role in product quality control of

sheet metal forming process. Surface microstructures of sheets have a great influence on the

development of lubrication films. In order to investigate the effects of the rolling direction of aluminum

alloy sheet and lubricant on the friction behavior in sheet metal forming, strip drawing test was used.

8/13/2019 On the Effect of the Orientation of Sheet Rolling Direction in Shot Peen Forming

2/2

The sample used was electric discharge texturing (EDT) surface. Lubricants, both with and without

additives, were used. The strip drawing tests were performed at angles between the sliding and rolling

directions of 090 deg. Variations in the sheet surface topography were analyzed by comparing the

sheet surface microstructures and its 3D surface parameters before and after the strip drawing test.

Results of the strip drawing tests indicate that the kind and amount of lubricant have great influences on

friction at the interface, and the lubricant with additives benefits improving the friction behavior

between the sheet and the tool. The EDT surface of the aluminum alloy sheet has an anisotropic

frictional property during deep drawing process due to different angles between the sliding and rolling

directions. When the sliding direction is parallel to the rolling direction, the coefficient of friction has the

highest value. When the angle between the sliding and rolling directions increases, the coefficient of

friction decreases. The surface microstructure of the sheets after the strip drawing test at different

angles between the sliding and rolling directions has been modified, and its 3D surface parameters

decrease significantly to a different degree.