| Mechanical expanding processing and corresponding equipments are keytechnologies to build production line of straight-seam welded pipe with largediameter. In the paper, the mechanical expanding process of straight-seamwelded pipe with large diameter is simulated by FEM and optimizationtechnology, and the principal processing parameters are optimized.The stroke of die during the course of mechanical expanding is deduced indetail, and the stroke of hydraulic cylinder in the expanding machine isformulated too. Similar to the previous research outcome, the formula obtainedby the present dissertation considers rounding stage and expanding stage duringthe course of mechanical expanding. In addition, the effect of initial contact statebetween die and billet on the stroke of die is taken in account. Moreover, theeffect of piston bar and expanding axis's elongation on the stroke of die isconsidered too, so it is a more accurate formula for engineering application.A large number of numerical simulations on the mechanical expandingprocess of line pipe are performed by MARC software. Based On thesimulations about the pipe specification such as Φ1 422×25.4 mm, Φ1 016×16mm, Φ813×14 mm, Φ610×13 mm and Φ508×13 mm, the effects of die'sradius, fillet radius of die's brim and expanding ratio on the deformation courseare analyzed in detail.The basic genetic algorithm procedure programmed in Python language isadopted to optimize the processing parameters of mechanical expanding process,and the procedure is combined with MARC software. Regarding die's radium,fillet of die's brim and expanding ratio as designing variables, aiming to theminimal roundness error, the key parameters of mechanical expanding processare optimized. The optimization results are consistent with analyzing results.The present outcome provides a theory basis for parameters selection during thepractical course of mechanical expanding, which is provided with importanttheory significance and practical values. |
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