Shape And Position Accuracy Of Digital Design And Evaluation Techniques

Recently, the development of CAD/CAM have acquired great breakthrough and remarkable achievement .But as an important part of mechanical production design and manufacture progress , the design of geometric tolerance depending on the expert system or experiences of deviser on the main has been in manpower or half-manpower state. Although it is convenient, utility ^ reliable and having put to use in engineering, the expert system go against to accomplish mathematics represent of geometric tolerance and can't do efficiency optimize analysis on all kinds of influent factor. It is difficult to realize tolerance information's transmitting and sharing in CAD/CAM integration. The design of tolerance has become a choke point restricting to CAD/CAM on second development. under this background the task is put forward.The studying target of this paper has three segment. The first one is analyzing relations between geometric tolerance item and ideal feature .. orientation feature based on the technologies of digital analyzing and describing . The relations will be basis to fulfill computer aided auto-forming geometric tolerance item. The second one is though opening out connections among geometric tolerance, dimension and dimension tolerance, using advanced technology and design means as dimension-chain technology optimization design feature modeling to build dimension-chain including geometric tolerance and evaluate it. Reaching the goal of optimizing geometric tolerance value . The third one is evaluating and simulating the result of design and assembly.The contents of this paper are as follows: (l)Based on GPS digital analyzing and describing technology, such as stable class characteristic and feature etc., considering the construct , capable feature and correlation influence factor of the design object, so the design of geometric tolerance is carried out; (2) Under analysis the relationship among geometric tolerance dimension tolerance and dimension of the classic part, considering the combination influences of dimension shape and place etc. by dimension-chain technology, synthesis dimension-chain is set up in which the geometric tolerance take part, simultaneity , it is evaluated by optimized method, so the mathematical model by dimension-chain is realized. (3)Abstracting the commonness of all kinds of dimension-chain, the template of dimension-chain is established; according to the character of separate part and the match rule, the template is modified and a synthesized dimension-chain is obtained. (4) With the traditional method of extremum and probability method, the dimension-chain is evaluated, simultaneity, the dimension-chain is optimized by Monte Carlo method, the value of geometric tolerance is certain. (5) According tothe functions of parametric design and second development of Solidworks, with object-oriented technique VB, the design and assembly are simulated.For the structure of the object controlled by geometric tolerance is complexity, the requires of function feature are variety, and the affecting factor is synthesize, so the computer aided design and control for geometric tolerance, especially the digital design and control ,is very difficult. The new generation GPS standard system presents academic basic and operation method. In GPS standard system, based on TTRS put forward by Clement and technologically and topologically related surfaces , there are seven stable classes , which regulate the geometry shape of workpiece. Every workpiece is combined by one or more classes , and give every stable class essence feature and orientation feature. In this paper, with the GPS digital description technology ,such as stable class feature and element etc., considering synthetically the structure function feature and correlation influence factors, the created method and regulation of geometric tolerance are analyzed.The value of geometric tolerance of part is influenced by function . dimension and dimension tolerance distortion suffered by force and heat and manufacture method etc. ,so setting up t...