Forming Three-dimensional Numerical Simulation And Research Of UOE Pipe

With the improment oil-gas pipeline safety performance,UOE pipes havebeen widely used in the critical oil and gas pipeline projects. UOE formingprocess starts with thick hot-rolled plate and goes through3main phases (1)theCUO forming phase,(2) the welding phase and the (3)calibration; the first phaseis composed by three steps: the C-forming, the U-bendingand the O-forming.UOE forming process is a complex elastic-plastic deformation and numerousparameters and correlation mold are needed. The phrases have great relevancesand all have different degrees of impact on the final shape quality.Therefore, itis very important to study the UOE forming process parameters on moldingquality with the finite element analysis.Mechanical properties of pipeline steel was measured by uniaxial tensiletests and cyclic tension and compression experiments. Based on elastic-plastic constitutive theory, kinematic hardening and mixed hardening model wereapplied to fit the experimental curve.Comparing the coincidence of the fittingcurve,combined model is better to describe the properties of pipeline steel.In this study,UOE CUO forming process three-dimensional finite elementmodel has been established, with the mixed hardening model which can describethe Bauschinger effect..In this process,the plates are crimped,formed into aU-shaped,pressed into an O-shaped. The simulation results of the process areobtained and compared with practical measurements to verify the correctness ofthe established model.UOE pre-welding process three-dimensional finite element model has beenestablished to study this process deeply. Taking into account the efficiency ofthe elastic deformation of the beams and the model calculation, iterativecalculation method has been used for a detailed analysis of the process ofpre-welding.In this case,roll beam model and static beam were alternate used.UOE expanding three-dimensional finite element model has beenestablished to study expanding process intensively taking overlap, relativeposition of expanding tools and rollers, re-expansion of the pipe ends and otherfactors into account.The effect of expanding process on the quality of UOEwelded pipe was analyzed with a number of factors, among which ovality is themost important. The research provides references to the prediction of the geometrical shape after expanding and to the design of the expanding processfor UOE pipes.