Research On Thickness Variation Of Cylindrical Parts In Deep Drawing Processing

In the process of deep drawing forming, the thickness of workblank changes.However, most designs of sheets forming don’t take the thickness variation ofworkblank into account, which doesn’t mean that the variation of thickness has noinfluence on the quality of part. In fact, the variation rate of blank thickness is one ofthe most direct parameter to scale plastic deformation degree. But accounting to thedifficulty in measuring the thickness of non-fringe-area, the practical significance ofthis parameter is really low. For sheet metal parts, thickness is an important indexwhich influences intensity, leakproofness and pressure bearing capacity of parts.Designers want to control the thickness variation of their products, but they lack anintuitive tool. At present, the academic circle only reaches an agreement on variationtrend of thickness in different mechanical areas, the quantitative conclusions andformulas have not yet been obtained.In this paper two methods are adopted, including a finite element experiment andtheoretical calculation. The research focuses on the variation law of thickness forcylindrical drawing parts in forming process. The variation curve of thickness will beexpected in the study.In finite element experiment, computer simulation experiments take place of thehigh-cost and long-period object experiment. The establishment of finite elementmodel is based on LS-DYNA finite element solver while selecting DYNAFORM asthe preprocessing program and modifying the K-format file to meet the requirementof our experiment.Then during the stage of data processing, data reading, classification andfiltering are realized by a series of programs written in MATLAB language, thevariation curve of thickness is also drawn automatically, which avoids a lot of manualoperation. At last, a universal fitting algebraic expression and a basic law aresummarized based on the analysis of segmental fitting curve with the help ofMATLAB math toolbox. For theoretical calculation method, it analyzes the potential relation betweendifferent areas of workblank, then builds a simplified flow model based on the flowof metal in deforming process. In this way, the thickness of modified part iscorrespond to thickness of flange surface in the deforming process, which coverts thecomplicated incremental deformation problem into a static equilibrium problem. Theintroduction of thickness parameter in mechanics equation will lead to an expansionof unknown variables. Therefore the A. A. Ilyushin’s Postulate and some otherformulas will be imported in order to establish the eight element differential algebraicequations solvable.The equations can be solved by using numerical calculation function underMATLAB environment. After getting the arithmetic solution of workblank’sthickness, the theoretical variation curve of thickness is easily obtained. In addition,deficiencies of the established model can be found by comparing empirical curve andthe calculated one.