Research On Deep Drawing Process For Rectangular Box Based On Radial Segmental Blank Holder

When the condition of die and blank size, lubrication, drawing velocity, temperature isconformed, Blank holder force(BHF) is the only parameter can be changed in deepdrawing process. Nowadays, BHF and BHF controlling technique are hotpot still. Generalsubsection binder drawing method, dividing the binder into several parts incircumferential direction can provide different force at different position. However, flangematerial thickness would be increased in deep drawing process, circumferential segmentalblank holder can not control material in radial direction. So, studying radial segmentalblank holder is significant.Numerical simulation of segmented blank holder in rectangular box deep drawing iscarried out in this thesis. The results show that when the relative length of the straightedge is greater than0.222, the thickness of corner part of the flange decreases along theradial direction from die opening to the outer edge of the flange while the straight part isof the opposite case. There is a great thickness difference between the corner part andstraight part along the circumferential direction. Wrinkling in the entire flange area isobviously occurred.Using energy method to export the calculation formula of critical blank holderforce(BHF) for the flange area of rectangular box. Analyzing the influence of the relativestraight length and the wrinkling model on the critical BHF based on the formula. Andaccording to the thickness variation, a new wrinkled waveform of the flange forrectangular box deep drawing is proposed. The critical BHF of overall blank holder andthe radial blank holder is calculated. The difference of critical BHF based on two methodsare7.74kN for axisymmetric parts and2.364kN for rectangular box when the distancefrom the divided position to die opening is20mm. The difference is always greater thanzero when the drawing conditions change. It is verified that the radial blank holdingmethod is better than the overall blank holder by the finite element analysis, and thesmaller relative straight length is, the better effect of radial segmental blank holder does.Experimental results demonstrated the superiority and feasibility of the radial segmental blank holding method. And the effect of suppressing wrinkling is the best when the ratioof the inner and outer BHF is1:2.Compound segmental blank holding technique is proposed by combining radialsegmental and circumferential segmental blank holding methods. Through analysis of theoverall blank holding technique, the radial blank holding technique and thecircumferential technique by using the finite element simulation and the orthogonal test, itindicates that composite segmental blank-holder technique is better than the other twomethods. When the blank holding force in the rounded area to the blank holding force inthe straight border area ratio is1:1, the width of the blank holder block in the rounded areais20mm, the inside blank holding force to the outside blank holding force ratio is1:2, theeffects of the composite blank holding technique is the best. The finite element simulationand the orthogonal test fully confirm the reliability of the results.