Research And Analysis Of The Key Factor In3D Tolerance Model

Computer-aided tolerance analysis means building tolerance analysis model based on three-dimensional solid mode, finding key sizes according to sensitivity and contribution data to do optimization design, so that to meet the assembly demands more economic fractionalization. This subject is based on a project agreement that signed by experts of Chinese ITER (International Thermonuclear Experimental Reactor) committee and the ITER International Group, select a typical block as the object of the tokomak vacuum chamber, use computer-aided tolerance analysis ways to do key factor analysis and optimization design of the assembly gap. Built the tolerance model and did tolerance analysis and optimization design in use of software CETOLof CATIA3D tolerance.. The main research works are as follows:1Build a typical block3D model. The Three-dimensional solid has been built model in CATIA. Re-assembled the simplified model according to the assembly requirement, defined with the fit requirements and adjusted the freedom degree with no constraint and under constraints to establish the intact assembly.2Discusses the key factor of sensitivity and contribution of the three-dimensional tolerance model in the dimensional chain effect. Analysis the first order and two order sensitivity and the size tolerance and geometric tolerance sensitivity method are studied in the3D tolerance model.3According to the typical shield block three-dimensional tolerance model, completed the analysis of assembly accuracy, get the ring3D dimension chain data sensitivity degree and contribution to identify the important dimensions assembly clearance dimension chain and non critical dimensions. This is the basis of the accuracy of the components for design optimization is provided. Sensitivity coefficient of the linear dimension is in the range of+1～1; the absolute value of sensitivity coefficient of the angle may be greater than1, it also may be0. The greater the absolute value of sensitivity coefficient, then the assembly accuracy is greater affected by the dimension.4The size precision assembly clearance of the typical shield block is optimized. According to the data of the key factor sensitivity and contribution, to improve or ensure the important dimensions of assembly precision accuracy; reduce the accuracy requirement of non important dimensions of size chain, making the design more reasonable.