H. K. Tönshoff
O. Meier
L. Engelbrecht

Extended forming limits using laser-assisted hydroforming

Steel Research International
12
76
920-924
2005
Type: Zeitschriftenaufsatz (reviewed)
Abstract
The motivation of the presented research work was to provide an approach to reduce the high fluid pressures and clamping forces needed in hydroforming presses to cup small form elements. Using local heating, small form elements like domes and creases can be formed at very low pressures of 2-3 MPa, whereas cold forming requires pressures which are 20-50 times higher. Apart from the proportion of forming temperature and work pressure, temperature distribution is very important, and can be adjusted by a special laser beam shaping optic or scanning processing head. The second method is more flexible in regard to element sizes and outlines, but has a lower thermal efficiency. Line network analyses were carried out showing great improvements in the resulting strain distribution. In order to characterise the general improvement of the material's formability, forming limit curves (FLC) were generated, using the bulge-test. The results prove the extended forming limit of the laser-assisted warm cupping process. For the investigations different materials were used: the deep drawing steel DC05, the aluminium alloy 5182 and the magnesium alloy AZ31.