Modeling And Application Of Kinematic Constraint In Precision Assemblies

The assembly complexity of Complex Electronic Mechanical (CEM) products increases as the degree of the integration, precision and dimension increases rapidly. Generally assembly modeling is to uniquely capture the structures and relationships between the elements. Therefore more requirements are asked to perform assembly modeling and analysis. Logically the assembly model is the accumulation of all the product information during the preceding development, which includes the data, structures, kinematic constraints and operation description and so on. At present no data structure or modeling methods exist that can be accepted commonly.Firstly the basic theories and relative concepts are researched systematically. And then Datum Flow Chain (DFC) is made on the mechanical assembly of CEM products. Takes an example for the micro hard disk drive, based on the liaison diagram of its structure, particularly for the assembly relationships of spindle-disk-clamp, DFC on the part level and assembly feature level are made respectively. Then according to the DFC on the assembly feature level, the expressions of spatial location relationship between the adjacent features are made. Later the factors on the variation of key characteristics are analyzed and the 3D variation accumulation is calculated by employing the error matrix.One of the important problems is the analysis of kinematic constraint of the parts in the assembly. Therefore, the thesis analyzes the kinematic constraint based on screw theory. What's more this method is applied to analysis the kinematic couplings, which is one of the typical precise locating equipment. At the end the method is also used to disk assembly and compared with the foregoing results. The conclusion is made that screw theory is effective to analyze the kinematic constraint of parts in the assemblies.Modeling and analysis method of kinematic constraints in the precision assemblies are studied, which will play an important role in the design and realization of product assemblies. This is valuable to improve the ability to the product development in the enterprises.