Research And Application On Intelligent Design Method For Die Face Of Automobile Covering Panels

In the early stage,rapid die face design and frequent updates of complex die face are required,and then rapid stamping simulation is performed to find forming defects and improve the stamping process plan.AUTOFORM controlled by Western capital is the only software that can meet this requirement.This not only causes large Chinese companies to pay high costs,but also lays huge hidden dangers for software being stuck.In addition,die face design is still subject to excessive reliance on experience and secondary design in the application of AUTOFORM.In order to break the technical monopoly of foreign software and improve the intelligence and integration of software,it has important theoretical research and practical application value to study a new intelligent design method for die face of automobile panels.Based on the project "Intelligent Design System for Die Face of Automobile Panels" commissioned by Shanghai General Motor Company and Dongfeng Nissan Motor Company,the paper conducts in-depth research and application development on the intelligent design for die face of automotive panels.An intelligent design method for die face of automotive panels is proposed,the intelligent method theory for die face of automotive panels is established,and the first domestic intelligent design system for die face of automotive panels that reaches the level of industrial practicality has been developed.A non-regular adaptive wireframe method for die face design is proposed.By constructing lightweight curve network,the wireframe method can assist designers in quickly designing and updating die face process plans.The integrated hierarchical update mechanism and modeling options can guarantee the stability of editing and updating of complex die face.In addition,the wireframe design model adopts characteristic curves to express the shape features of die face,and then extracts and classifies the critical control parameters of complex geometric models,which lays preconditions for quantitative adjustments to realize the intelligent design of die face.An intelligent design method driven by rule and template is proposed.Through indepth analysis for panel shape and forming characteristics,combined with plastic forming theory and empirical specifications,intelligent modeling rules and optimization rules are established.The intelligent modeling rules are used to generate high-quality surfaces that meet the process specifications and are conducive to uniform deformation of the material.The intelligent optimization rules can adjust quantitatively characteristic parameters based on the results of numerical simulations,which overcomes the defect of slow convergence of traditional optimization methods.The intelligent template library for automobile panels is constructed to realize fast and precise reuse of die face design process,which solves the application problem of the traditional die face database of automobile panels.A series of key modeling algorithms for die face design are developed.The rolling circle algorithm is developed to solve the problem of curve offset,and then is extended to variable axis systems,which is widely used in various problems such as concave recognition and curve mapping.The hole filling algorithm constructes smooth constrained surfaces on irregular curve grids.The quality and stability of surface construction are improved siganificantly by applying the energy minimization optimization strategy based on triangle mesh.The surface skinning algorithm based on the center spine solves the generation problem of rib-like surface features.The parameterized geometric model can not only realize rapid creation and editing,but also accurately control the surface shape.By studying section curve template,curve mapping relationship and adaptive guide curve construction,the addendum surface algorithm solves the problem of bridging two complex surfaces,and realizes the rapid parametric modeling of large complex surfaces.Applying the intelligent design method for die face,this paper has developed a whole process oriented intelligent design system for die face of automobile panels based on CAD platform NX.The system utilizates feature correlation and navigation tree to structuralize die face design process,which can improve significantly design efficiency and stability.Conmbined with the sheet metal forming simulation system,FASTAMP,the system integrates seamlessly gometric modeling and numerical analysis modules,which lays the foundation for the subsequent solution of secondary design problem.The system has been tested on 44 actual complex automobile panels and the test results show that the developed system achieves good behaviors in terms of ease of use,stability,surface quality and intelligent design and has basically reaches the level of industrial practicality.