Effect Of Mould Parameters And Process Parameters In JCOE Forming On Welding Quality

JCOE multi-step progress forming process as a large diameter straight welded(LSAW) steel pipe manufacturing technology is widely used in many countries foreconomic investment and adapting market. At present, most technical parameters designin JCOE forming still depended on the experience of workers for the length of routes,many forming parameters and complexity of mould structure. The production methodslead to welding pipe geometry error, low productivity efficiency et al. real problems.Meanwhile, the uncertainties such as material properties gave rise to unstable quality ofpipe in production. Taking JCOE forming process of Φ1219mm×22mm×12000mm pipefor example, the forming characteristics, optimization of technical parameters and productquality design are considered in this paper, in which efficiency, accuracy and quality asoptimization objective, the die parameters and process parameters of various processstages as design variables, JCOE forming die parameters and process parametersoptimization plan are discussed.Firstly, three bending mode mathematical model based on the Hill exact theory areestablished including crimping, symmetric bending and asymmetric bending, in which theradial stress, wide stress and neutral layer shift can be considered. the theory formulas ofstress, strain, bending moment, forming force and springback are obtained in the threekinds of bending mode. The results shown that the mathematical model meet well withexperimental results. The mathematical model not only analyzed the basic deformationcharacteristics of JCO forming, but also provided the theoretical basis of technicalparameters. At the same time, the establishment of the tube geometric programmingmodel of JCO in ideal forming state. The quality evaluation of different forming stages areproposed as JCOE systems analysis foundation.Secondly, a multi-process continuous forming finite element model is establishedusing the finite element analysis software ABAQUS including crimping, JCO forming andmechanical expanding. And the finite element model is verified by experiments, Thesimulation results revealed the stress/strain state in forming process, the geometry of forming and mechanical properties et al deformation characteristics. The effects of dieparameters and process parameters on JCOE forming quality based on geometricprogramming model of pipe are obtained.Thirdly, Taking crimping, JCO forming and mechanical expanding as researchobject, response surface models of JCOE forming quality are established using radial basisfunction (RBF) response surface method by simulation results from Latin square designsimulation program for the sample points. The optimal JCOE forming process plan isobtained by grey relation anaysis and genetic algorithm for cross section geometricaccuracy and forming efficiency. The optimization results are verified by finite elementanalysis methods. The twelve times of bending are reduced in optimization program onthe condition that welding pipe cross section geometric accuracy is guaranteed. So theproduction efficiency is obviously improved.Finally, The response surface models considered material properties are builded bysimulation program thougth taguchi design method. Probability distribution of weldingpipe forming quality is sampling analysed by Monte Carlo simulation. The analysis resultsshown that the welded pipe robustness of original design scheme and deterministicoptimization scheme needs to be further improved. In this paper, according robust designprinciple and six sigma quality criteria, the JCOE forming robustness optimized designbased on genetic algorithms, Monte Carlo simulation, and grey relational analysis arecompleted. Through the comparative analysis with deterministic optimization schemeshows that two times of bending are increased in robustness optimization scheme, butwelded pipe forming quality robustness is increased significantly.In order to improve effectively and control forming quality, the effects of JCOEforming die parameters and process parameters on welding pipe forming quality, JCOEforming die parameters and process parameters optimization and JCOE forming weldingpipe quality robustness design are proposed. Manufacturing quality and high efficiencyrequirements are focued. The technology systems of parameters manufacture for LSAWsteel pipe are developed further.