Theoretical Research On The Process Of Necking For Cartridge Globular Female Die And Finite Element Simulation

Necking is a forming process that using molds to narrow openings of metal pipe. Necking is mostly the conical and spherical shape, whose aim is to freely connect the large-diameter pipe with a small diameter tube, and which widely used in production for the boiler, automotive, aerospace, and other equipment enterprises. During actual machining process, due to the lack of theoretical guidance, most used their experience to estimate and determine the necking process, so the effects of necking and economic benefits are of not working well.Through visiting the boiler manufacturing, food processing and paper mills to go on the actual research and searching related information, for necking for cartridge globular female die used much in engineering practice, but the reality is very weak theory, this article set me to choose metal tube boilers-Low and Medium Pressure Boiler using necking for cartridge globular female die of Seamless Steel Tube (GB3087-1999)as the research object, in order to combined stress equilibrium equations with simultaneous equations to yield a mathematical model, and integrated necking process test, the mechanical properties of materials testing and ANSYS finite element simulation analysis as a means of analysis to study. Researched the main technical parameters of process of necking for cartridge globular female die-necking forming force, considered three factors which ignored in the existing analysis of the calculation:the effects of stress field for the entrance to the additional deformation of die moment, the impact of the deformation hardening in stress field, the impact of changes in the thickness of wool in stress field.Research achievements are as follows:1. Find the metal hollow tube necking spherical shape of the tangential stress and the relationship between process parameters to establish new calculation formula for force of necking about cartridge globular female die: 2. By the test for materials of steel pipes tensile, and confirmed that the parameters of the mechanical properties in theoretical calculating formula, specially got this material the strain hardening module.3. Through technology and process test results and this article necking force derived value calculation to verify the formula in the theory and practical scientific rationality.4. Finite element model established is to be able to use finite element to simulation analysis the process of forming necking. Contrast simulation results in necking forming process and test results, and further displacement and stress from the point of view of verification of the correctness of the derived formula.The significance of the research:formula for calculating that considering the additional bending moment, deformation hardening and tube thickness of the new cartridge globular female die necking forming force is to improve the relevant theory, provide a theoretical basis for the production of cartridge globular female die necking forming and the development of necking process, and causes it to rise from the traditional qualitative analysis to the quantitative analysis, combined with finite element simulation analysis, can greatly reduce the test-mode process, to improve the accuracy of necking, lower production costs, and the economic benefits will be better.