Study On Quality Control Strategy And Simulation System Development Of UOE Pipe Forming

The goal of quality control of the UOE forming process is that ellipticity and convex amount of pipe reach given precision. The process of UOE is integrated multi-operation, which contains edge bending, U-forming, O-forming and expanding. Technological parameters which have something with the quality of pipe impact on each other. It is important to control the forming process of UOE to improve the final product quanlity by compatibility of deformation in each stage.The fundamental theory of the forming process of UOE was studied in this paper. The formulae for calculating forming force and dies stroke of edge bending, U-forming and O-forming was deduced, and the predictive expression of spring-back was given in each working procedure.The FEM model for continuous simulation of UOE process was built, and deformation mechanism of sheet metal during the forming process were disclosed. The deformation of sheet metal contains bending, reverse bending, compress and tension. Bending is the main deforming in edge bending and U-forming; Local reverse bending and circumferential compress are main deforming in O-forming; Circumferential elongation and wall thickness reduction in expanding. The section have two regions whose residual stress is rather large, the intermediate zone of the arc parts and straight-wall section and the domain of straight-wall section where bending happened firstly in U-forming.It is hard to get a simple mapping relationship between technological parameters and the final product quanlity, as UOE process belongs to multivariate and close coupling elastic-plastic deformation. The quality control parameters and index system were established in this paper through determining the supposed quanlity control parameters of the stage by the forward one, which was made by controling ellipticity and convex amount of pipe. The qualitative and quantitative analysis of quality evaluation indicators influence on the quality of pipe is conducted and the quality control strategy of UOE pipe processing is proposed. According to the quality evaluation system, a virtual simulation system has been developed to simulate the forming process of sub-merged arc welded tube with large diameter using UOE method. The system is a secondary development of MSC.Marc which consists of visual menu, automatic generation of parametric model, automatic generation of quality evaluation indicators, numerical simulation with man-computer interaction and forming defect analysis modules. Once required technological parameters is given, with the aid of the module of automatic generation of FEM model, what is needed is only several simple operations to establish planar or 3-D FEM model, then the forming processes of steel plate from edge bending till expanding continuously. It also allows user to conduct subsequent simulation from the step where is a revision of the technological parameters is made according to the results of the forgoing simulation steps. After the simulation, important data on load, spring-back, size of product, shape tolerance and distribution of residual stress of product are provided automatically by the system. This system provides user with a convenient platform for UOE process simulation and analysis. The findings and simulation system have been applied to the new project of producing pipe line with large diameter in Baosteel.The ellipticity, convex amount and forming force of O-forming were measured in the experimental study. The experiments results are in good accordance with theoretical analysis and numerical simulation.