Welding Process Optimization For Invar Steel Mold Used In Civil Aircraft Composite Structures

For the large deformation during the welding assembly of Invar steel moldwhich used in large aircraft composite structures and its high requirements ofwelding deformation control, carry out the welding process optimization of Invarsteel molds. Adopted a method that combines the virtual welding process, theauxiliary welding process, theoretical analysis and Invar steel welding experiment,carried out research of Invar steel welding defect control, optimization of moldcomponent welding process and technology of auxiliary welding deformationcontrol, to achieve the target of Invar steel mold welding deformation control, andform mature welding process.First, welding process is studied and explored in the different thickness of Invarsteel, based on getting a good weld, use non-destructive testing techniques andobservation of the weld microstructure to study distribution and reasons of thewelding defects, and identified by experiments, ultimately, acquired Invar steelwelding defect control policy.Secondly, measured high temperature performance parameters of Invar steelthrough experiment, established welding finite element model of typical test piecesand large curved surface Invar steel model. Check the welding heat sourceparameter through experiment, based on the verification of the finite element modelis reasonable, analyze welding deformation of thick Invar steel plate, then choosethe better forms of welding groove and welding process. Based on the research ofthick Invar steel plate, analyze welding deformation and residual stress of largecurved surface Invar steel model. Optimize the process through different weldingprojects, and then get the mold structure’s better welding process project.Finally, based on the Invar steel mold’s finite element model of optimizedproject, study the simulation of two commonly process measures used for weldingdeformation, the negative distortion method and the flame straightening. Approachthe optimal presupposed initial deformation through iterative method, and ultimatelyachieve the purpose of welding deformation optimization. Analyze the flamestraightening after weld in the initial condition of welding residual deformation toget regular pattern of residual deformation. Effective verify the effect of the flamestraightening on reducing welding residual deformation.This article researched the welding process, welding defects, groove type,welding deformation, deformation control measures after welding, and so on, andprovided with great significance in localization of Invar steel molds.