Cross-Platform Exchange And Rapid Reconstruction Of Assembly Constraints In Automotive Components

The development of automotive products is realized by a heterogeneous network of OEMs and different vendors at all levels.How to exchange product data completely and accurately between different CAD systems in different OEMs and suppliers has always been an important problem that plagues the industry.Among them,the STEP 3D data exchange standard(AP203 and AP214)introduced by the International Organization for Standardization(ISO)has become the most common solution in the mechanical and automotive industries.The 3D geometry data and partial assembly information can be effectively exchanged through the STEP standard(based on the AP203 and AP214 application protocols),but assembly constraint information is not included.For downstream engineers,how to rebuild these missing assembly constraints in complex,multi-level assemblies is a very difficult task,even with the full assistance of upstream engineers,it is still a very time consuming and challenging work.Based on the STEP data exchange standard,this paper attempts to supplement the additional assembly information description file,the target system automatically reconstructs the missing assembly constraints,and transform the previous manual reconstruction process into an automated process to improve design quality and efficiency.This paper takes the mainstream design systems Dassault CATIA and Siemens NX,which are commonly used in the automotive industry,as an example.The above ideas are realized and verified through secondary development.Based on the above work,this study explores the mapping and matching of assembly constraints between different CAD systems,and defines a general exchange protocol for assembly constraints between complex assemblies;constructs the front-end assembly constraint information traversal and Output module,back-end assembly constraint information parsing and reconstruction module.In this paper,a generalized incremental method is adopted in the process of assembly constraint information description and reconstruction.Constructing a substantially equivalent assembly constraint by generating simple geometric elements in the back-end assembly to avoid complex mapping of assembly information between different CAD systems.Though definition and description of assembly constraints for different CAD systems are different,the method provided in this paper can be used as a universal solution.At the same time,for the old assembly files that cannot trace the assembly information,this paper also discusses the automatic and semi-automatic assembly constraint recognition method to accelerate the manual reconstruction efficiency.The front-end system of this paper is developed by using Visual Basic secondary on the Dassault CATIA platform,based on the OLE Automation mechanism provided by CATIA.The back-end development system of this paper uses a variety of development technologies including UFun,NX Open,and Knowledge Fusion,and is completed by using Visual C++ on the Siemens NX platform.Based on the above conception software module,it shows obvious advantages in the product testing process.For the more than 20 complex automobile assembly models provided by the OEM,the substantial equivalent assembly constraint information is completely reconstructed.The results show that the tool can be a very valuable addition to the STEP exchange protocol.Moreover,this versatility-targeted solution can be easily applied to the assembly information exchange between other CAD systems.