Study On Key Technologies Of Trimming Line Unfolding For Automobile Panel Based On NX

It is the determination of trimming line’s location and size for the automobile panelflanging parts that has been a technical difficulty during stamping process, which hasneeded repeatedly test in practical production, wasted lots of manpower and materialresources, and influenced the mould design cycle seriously. CAE softwares i.e. AutoForm,Dynaform and Pam-stamp can simulate flanging forming and optimize the trimming line’ssize iteratively, but need to finish the modeling of drawing and flanging process, also thecalculation time is very long, there have been great difficulty during the actual application.Besides, it needs importing the process mold through intermediate formats, such as IGES,during the simulation using these CAE softwares, and there is often data loss duringconverting, this also has affected the CAE technology application. So developingCAD/CAE integrated system, can make the CAE technology application more convenient,and have an important meaning to ensure the product quality and shorten the developmentcycle.The thesis is supported by national natural science funds projects(No.50905066),numerical control equipment state major R&D projects(No.2010ZX04014-072&No.2009ZX04013-031), and aims at developing a3D trimming line unfolding and flangingforming performance analysis system using second development tools UG/Open.This paper has studied the process characteristics of flanging and trimming lineunfolding, Inverse Approach of FEM, CAD/CAE integration technology, applicationdevelopment technology of UG NX, spline curve fitting and other basic theory anddevelopment tool, demonstrated the feasibility of system development, then completed thedesign and development of the whole system architecture and functions for TUW.This thesis has raised two kind of boundary treatment methods have according to theactual flanging process, and the algorithm of automatically adding the fixed constraint hasbeen mainly studied; aimed at the problem that the unfolded trimming line can not reachthe requirements of NC machining because of the local curvature fluctuations caused by the defects in UG NX’s surface conversion and meshing, this thesis has proposedsubsection/noise reduction/elimination of unnecessary nodes methods, optimized thecontrol nodes, then fitted the B-spline curve by the local energy method, improved thefairing performance of trimming line; also this thesis has put forward several steps to dealwith the trimming line after unfolding, including cut-off, reconstruction, bridge andcombination.Actual application has shown that the trimming line after smoothing can be used inNC machining. Through the comparison with experimental result, validated that theprecision of trimming line unfolded can meet the requirements of actual process, and canbe used to guide practical production.