Study On Drawing Law Of Box Part With Step Wall

There are many parts with step wall in the fields of automotive, aeronautics andastronautics, machinery and electronics, and some other areas. This article mainlystudies the drawing deformation law of box parts with step wall, which brings a basis ontheory for complex parts forming and also can be referred to the researches going on inthis area.In this paper, with the aid of finite element software, the box parts forming law andthickness distribution were analyzed from five aspects, which are equivalent strain,material flow pattern, thickness variation of blank， forming defects and stressdistribution. In this study, orthogonal experiments were designed to obtain the influencelaw of geometric factors on wall thickness thinning and fracture. Then the shapes ofwrinkles in the stepped area after forming process were analyzed by means ofestablishing cross sections. Heights and spans of wrinkles were quantified by usingcoordinate transformation method, which gives a better way to show the effect of stepsize on wrinkling accurately and intuitively.Based on the sample data obtained from the early orthogonal experiments, the BPneural network was established to predict the wall thickness of forming part, thusjudging the quality of forming parts. Finally, by designing the physical experiments,three groups of formed parts under different parameters were obtained and the thicknessdistributions of formed parts were measured.The research results show that the corner of punch thinning the most seriously afterforming. Material accumulation and wrinkle will occur due to dangling blank in steppedarea without sufficient space to flow along with intense deformation.The higher of the overall height and the deeper box section height, the worse it isfor forming. The bigger of the width of deeper and shallower box section, the better it isfor forming, and so is ladder corner radius. The influence of die fillet radius onthickness indicator is the same as that of ladder corner radius which is strict monotonous,the bigger die fillet radius is, the more conducive to forming process.Wrinkle shapes in stepped area of box parts with step wall are diverse and complex,including area distortion, concave, wrinkled peaks in concave area，multimodal convex，unimodal convex and some other wrinkles morphology. On the premise of ladderexistence, the smaller the step width and the greater height, the more serious thewrinkles are. Step width influence on wrinkles morphology is greater than height, to acertain extent determines the wrinkle appearance characteristics.BP network established with sample data without normalization processing，which has9nodes in hidden layer has a better prediction effect.Thickness distributions obtained from experiments are in conformity with thesimulation results, and corrugate morphology of parts is consistent with wrinkle shapecurve, which verified the accuracy of simulation results.