Study of blank-holder technology on multi-point forming of thin sheet metal

Multi-point forming (MPF) is an advanced flexible manufacture technology, and the technology results from the idea that the whole die is separated into small punches that can be adjusted height. This idea is applied to the traditional rigid blank-holder (RBH), so flexible blank-holder (FBH) idea can be obtain. Different technologies about RBH forming and FBH forming are simulated in this paper, and the impact on wrinkle, crack and forming limit from the two different technologies is also analyzed. Furthermore this process is simulated by explicit software (LS-DYNA) for the saddle workpiece with two kinds of thickness and the experiment is completed, Results indicated that the sheet with large deformation will wrinkle in the RBH forming, until blank-holder force (BHF) increasing the sheet cracked. But under the same condition the sheet is good in the FBH forming. When 1/2 area of blank-holder surface is cut out, and BHF is increased, the sheet also can be well gained. So the technology of FBH can sharply increase material utilization ratio, improve forming limit and decrease most disfigurements. (c) 2006 Elsevier B.V. All rights reserved.