Research On Intelligent Interactive Design System Of Reconfigurable Flexible Tooling Based On Feature Driven

The production mode of "multi variety,small batch" of automobile puts forward stricter requirements for development cycle and production cost.Welding fixture is an important process equipment to ensure the welding quality and accuracy of the body.Its design and manufacturing efficiency has an important impact on the welding process cycle.At present,the Computer-Aided Fixture design can improve the design efficiency to a certain extent,but its intelligence and flexibility still seriously restrict the development efficiency of automobile welding fixture.Therefore,how to use the fixture structure design knowledge to realize the intelligent design of body welding fixture and shorten the design cycle has become a new research hotspot.This thesis takes the design process of body welding fixture as the research object.Aiming at the problems of heavy task and long design cycle of fixture design caused by the complex structure characteristics of body parts,the key technologies of the intelligent interactive design system of reconfigurable flexible body welding fixture are studied.The intelligent design technology of computer-aided fixture is studied in theory and method,and the prototype system of flexible fixture design is developed to verify the feasibility of the theory and method.The main research work of this thesis is as follows:(1)Studying the theory and method of NX secondary development method,comparing and analyzing the principle and architecture of NX / Open and UG / Open development method,and expounding the other development tools,such as Journaling,Block UI and Menuscript.Based on the above foundation,a method suitable for rapid development of enterprises is proposed,which provides technical support for the subsequent development.(2)Based on the analysis of the characteristics of the body structure,a modular flexible combined body welding fixture scheme of "standard parts + non-standard parts" is proposed,and a variety of common typical fixture structures are obtained.The arrangement and combination of standard parts and non-standard parts of different types and specifications are used to realize reconfigurable flexible clamping and positioning of vehicle body.(3)In NX software platform,the 3D model template of fixture standard parts is created,and then the fixture standard parts library is constructed to realize the management of fixture standard parts.Based on the parametric modeling theory and synchronous modeling theory,an adaptive modeling method for non-standard parts is proposed,which can realize adaptive and fast modeling for complex body structure features.(4)Studying the design and assembly process of flexible body welding fixture,and constructing an intelligent number font model.A hybrid reasoning fixture type selection algorithm based on rule-based reasoning and case-based reasoning is proposed.On the basis of practical design experience,the fixture specification reasoning is carried out to realize the rapid selection of standard part specifications according to the key dimensions of positioning and clamping.Then,based on the object space coordinate transformation theory,a fast semantic search assembly feature algorithm is proposed to build assembly constraints to achieve automatic assembly.Finally,the adaptive modeling design of non-standard parts is completed based on the features,so as to complete the whole intelligent design process of welding fixture.(5)Based on the above theory and method,aiming at the design requirements of body welding fixture,the intelligent interactive design prototype system of flexible body welding fixture is completed through NX secondary development.The feasibility of the system is further verified by taking the design of the welding fixture of the front floor assembly as an example.