TEHNOMUS - New Technologies and Products in Machine Manufacturing Technologies 64 AN ANALYSIS OF THE RESTRAINT FORCE IN DEEP DRAWING OF THE RECTANGULAR PARTS Paunoiu Viorel Dunarea de Jos University of Galati, Faculty of Mechanics, Manufacturing Engineering Department Domneasca Street no. 111, 800201, Galati, Romania viorel.paunoiu@ugal.ro Abstract: In deep drawing the binder provides the restraint force necessary to avoid wrinkling, tearing or excessive thickening of the blank. For complex parts such rectangular ones, different schemes for applied the restraint force are applyed. In the paper the scheme of segmented BH is compared with the conventional one. The numerical study based on FEM is applied to investigate the part quality in terms of thickness, force and springback variation in both cases. The simulation results are then compared with the experimetal ones when a conventional binder is used. Finally for this study conditions the segmented BH scheme emphasizes the improvements in the part formability. Keywords: Segmented BH, Deep drawing; Sheet metal forming; Finite element analysis; BHF 1. Introduction The quality of a deep drawn part is influenced by a number of variables. These include material properties, die design, and process parameters such as the drawing ratio, friction conditions as well as the blank-holder force, BHF [5]. In particular, the force exerted by the blank-holder (BH) on the sheet supplies a restraining pressure which controls the metal flow into the die cavity [2]. This restraining action is largely applied through friction. Excessive flow may lead to wrinkles within the part, while an insufficient flow can result in tearing [6]. Various BH restraining techniques had been studied [3, 4, 7] for improving the sheet metal formability such as the segmented BH scheme Individual segments of the BH are controlled independently of the each others [8]. The method also enables holding with locally different BHF on each segment. Segmented BH solves very effectively the problem of holding the blank flange of parts with various thicknesses. The disadvantage of tools with segmented BH is that they still are very expensive because of their particular design. Figure 1 presents a first application of the segmented BH scheme, available for forming cylindrical parts. F 1 F 2 S 5 0 2 6 3 4 A A B B S 1 5 a) b) c) d) Figure 1: Die with segmented blank-holder, cylindrical parts application [13] Another application of this technique is in the rectangular panel forming (figure 2). The four corners of the rectangular panel remain the critical deformation areas (figure 3). The deformation in the corners creates a large volume of material trying to be compressed and stuffed over a die radius with a much smaller