Effect of coining on springback behaviour

International Deep Drawing Research Group 37th Annual Conference

Gösling, M.^1 ; Güner, A.^2 ; Burchitz, I.^3 ; Thülig, T.^1 ; Carleer, B.^2

BILSTEIN GmbH and Co. KG, Im Weinhof 36, Hagen

58119, Germany^1

AutoForm Engineering, Joseph-von-Fraunhofer-Straße 13a, Dortmund

44227, Germany^2

AutoForm Engineering B.V., Industrieweg 2, LB Krimpen a/d IJssel

NL-2921, Netherlands^3

关键词: Accurate prediction;    Automotive parts;    Deep drawing tests;    Rolling direction;    Shell formulation;    Thickness direction;    Through-thickness;    Through-thickness compressions;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/418/1/012106/pdf
DOI  :  10.1088/1757-899X/418/1/012106

来源: IOP

【 摘 要 】

Especially due to utilization of high strength steels in automotive parts, accurate prediction and reduction of springback have gained more importance in the recent years. One of the widely used approaches to reduce the springback in deep drawn parts especially in and around the bent regions is coining (restrike operation). In this method, the sheet material in the springback-relevant regions is compressed between two rigid tools having clearences less than the sheet thickness. By this way, compressive stresses and strains are superimposed and therefore the bending effects are reduced. During coining, plastic deformation occurs in the thickness direction. In order to predict this behavior in process planning numerical simulations should be capable of considering the effects of through-thickness compression. In order to analyze this effect, axisymmetrical deep drawing tests were performed. In a further step, the bottom surface or the radius region of the geometry was compressed between the punch and additional tools. To analyze the springback behaviour, drawn geometries were cut along the rolling direction, so that the residual stresses are released. The same procedure was also simulated with shell elements having enhanced formulation to account for through-thickness deformation. Experimental springback results show that the coining process influences the springback and this can be captured by the enhancements in the shell formulation.