Analysis And Numerical Simulation Of Cold Extrusion Forming Process On Thin-walled And Cone-shaped Part

With the rapid development of computer technology and gradual penetration of studying FE's theory, the technology of plastic forming numerical simulation has become one of methods which usually were used to study metal forming. This technology has many characters such as strong functions, high precise and broad application. It can widely be applied to numerical simulation to deformation body with arbitrary geometry. At the same time, when body conditions, contact conditions and other many influencing factors are taken into account, it will simulate the whole process of cold extrusion forming and status of metal flowing. Information of metal flowing and mechanics during deformation process is also acquired. Under the background of precision forming on cold extrusion, the process of thin-wall and cone-shaped part's cold extrusion forming has been numerically simulated by use of technology of plastic forming numerical simulation and the universal non-linear FEA software, Deform3D in this article.Firstly, some key questions in numerical simulation have been dealt with technically in this article, for instance, contact, friction, description of mold's geometrical information , automatic recognition of dynamic boundaries and so on. Simulation model used in analysis was set up by simplification and hypothesis. In simulation, metal produced large deformation and strain, so excess large deformation lead aberrance of the mesh. Also subsequent analysis of taking it as reference model was gone along and finished on poor quality of mesh. Ultimately the precise of result was influenced and analysis was forced to be aborted. Therefore the technology of automatic remesh in Deform3D software has been employed to correct mesh aberrance on account of excess deformation. At the same time excellent mesh has been regenerated automatically and calculational precise has been enhanced, which ensure that subsequent calculation carried on naturally.Secondly, this article analyzed forming mechanism of the thin-wall and cone-shape part's combined extrusion and reasons of producing some typical flaws during this part's combined extrusion, such as crack, material scarcity bottom of the part, collapse and score on the part's face, and then some measures were brought forward accordingly. In this article, the reasons bringing on crack have been analyzed specially. Material property, friction, mold constructionand condition on the part's face have some important influence on emergence of crack. By modifying some parameters and simulating repeatedly, some measures dealt with crack have been presented.This article also summarized the rules of extrusion forming of parts with thin-wall and cavity finally. General ways resolving some flaws commonly appeared this kind of parts' forming were put forward. Those can offer theoretic foundation for mould design and setting technical parameter of this kind of parts' extrusion forming and gave some guide for practical production.