Research And Application On Optimization Methods With Auto-Body GD&T Design Process

In auto industry,the GD&T,known as 'Geometric Dimensioning and Tolerancing', is a language to indicate the geometric dimensions and tolerances of the auto parts in terms of signs, and it is also the thoughts for designing and marking parts. The standard and process of the GD&T design depends on the vehicle company. The GD&T design covers the whole process of vehicle parts designing and manufacturing. It directly affects the vehicle manufacturing and designing quality, as well as affects the auto-body appearance and the design cycle and costs. The conventional GD&T design process is characterized by its complexity, flexibility, dependence on experien- -ce and fuzziness, which is mostly created by hand, causing that the former design samples and experience can not be fully reused as well as much repetitive work is brough up, so the design process is inefficient and ineffective. In this paper, the target is to do research on the optimization method and the application in GD&T design process based on computer-aided-design technology. The problems existting in the conventional GD&T design process can be resolved by taking advantage of CAD's merits on parametric and intelligentize design. Setting up a knowledge database model which possesses rules integrated with auto-body GD&T design software plant- -form to realize the reuse of existting project experience and expert knowledge,and based on the database model an optimization system for auto-body GD&T design pro- -cess is to be developed with UG secondary developing tools. With the system the prolems of inefficiency and low level in GD&T design which is caused by lacking of data, experience and knowledge can be resolved, so this system can provide the desig- -ners with instructions,reduce repetitive work and shorten design and manufacture cy- -cle. The main content of this paper is as follows:First, beginning with GD&T's defination and function, an overall explaination on the significance of GD&T design in auto-body design and manufacture is to be given, and an introduction is to be made on the auto-body GD&T design flow and methods. The flows covers:function analyze, tolerance study, datum system, tolerance calculate and product drawings. The methods contain how to design the datum system, how to design the tolerance and how to make the measure points. All of these can provide a theoretical basis for optimization methods with auto-body GD&T design process.Moreover, a database model which is charcaterized by its knowledge function is to be set up with the database's merit on intelligentize management of knowledge infor- -mation. Through analysis and classification of the existting dominant knowledge and recessive knowledge of auto-body GD&T information with the database model, and analysis on typical GD&T design samples, an auto-body GD&T information knowle- -dge database is to be created based on the data analysis, database entering and data matching rules which are summarized from existting project design rules and expert knowledge. The knowledge database is aimed to provide a background data basis for GD&T parametric and intelligentize design process.Last, an optimization system for auto-body GD&T design process is to be design- -ed based on knowledge database using UG secondary developing tools. Through calling the data in database by some rules,it can reuse the existting design experience, so as to simplify the whole design process and finish the GD&T design work quickly.In summary, this paper makes the auto-body GD&T design as the core of this pap- -er. And, does research on the GD&T design process and method, based on which the computer-aided-design technology is introduced into optimization work for GD&T design process by using knowledge database technology and UG secondary develop- -ing technology. Last,an optimization system for GD&T design process is to be set up to make GD&T design efficient and accurate.