Research And Optimization Design Of Process Parameters On The Deep Drawing Of Nickel-coated Sheet

Nickel-coated sheet is a kind of new composite material, which have corrosionresistance, wear resistance and high strength. By the methods of surface modification,then electrodeposition of nickel on the mild steel substrate, and then through specialcraft processing. Nickel-coated sheet is also a kind of excellent performance of newbattery shell material. However, many of Nickel-coated sheet need deep drawingbefore using it, during this process, the actual forming process parameters (molddesign parameters and the material itself) are often have certain fluctuation near thedesign parameters. These parameters are usually mutual coupling and restriction,which influences the quality of stamping parts in different degrees, and eventuallylead to some kinds of failure phenomenon such as wrinkling and fracture.In the past, we often use Forming Limit Diagram to study the performance ofsheet metal forming, however, FLD is highly affected by the loading paths. Using asingle forming limit method can not effectively solve Nickel-coated sheet failureproblem in sheet metal stamping process. In order to reduce the production cost,achieving a good formability. Aiming at the problem of thickness distribution in theprocess of forming，this article attempts to analyze the formability of Nickel-coatedsheet. Starting from the metal sheet thickness and thinning. The main innovationpoints are as follows:(1) The failure problem of Nickel-coated sheet in sheet metal deep drawing aresimplified as its simple stress-state of plastic instability problems. Using the basictheory of composite materials, the fracture of punch corner is converted into thecomposite board material uniaxial tensile instability problem, the critical stress andstrain values and the relationship between the components of material instabilityparameter is obtained by using the theory of dispersion necking instability.(2) Through the analysis of the stress and strain state of the Nickel-coated sheet,explain why thickness distribution of Nickel-coated cup is not homogenized. Basedon the numerical analysis, the first step of nickel coating battery shell deep drawinghas been researched, by using the ANSYS/LS-DYNA FEM software. In addition thefinite element results are compared with experimental results and numerical imulationfor validation.(3) Based on the predict of thickness distribution and thinning of the deepdrawing circular cup, the significance process parameters(blank holder force, friction coefficient, initial thickness and concave/convex die radius, deep drawing dieclearance, etc.) on the deep-drawing characteristics of Nickel-coated sheet isdetermined, at last, the influence of process parameters on the quality characteristics(thickness variation) of the circular cup and their percentage contribution is calculatedusing Taguchi method.(4) In view of the main process parameters, the paper puts forward a kind ofmulti-objective optimization method based on experiment design and response surfaceapproximation and Pareto genetic algorithm to research the process parameters ofNickel-coated sheet.