Establishment Of Assembly Parametric Model Based On Dimension-driven

In recent years,parametric design has developed rapidly,and its storage design process shortens the design cycle,which caters to the fast updating market.At present,the research on parametric design of assembly geometry mainly focuses on two aspects: parameterization of parts in an assembly by using secondary development tools,establishment of database of assembly parts and completion of design by calling data,while the research on Parameterized Design of part size model in the whole assembly is less.There are complex dimension relations in assembly.Clearing up the relationship between dimensions is the premise of dimension driving parameterization.For this reason,scholars use the theory of "graph theory" and "tree" to model the dimension relationship and part relationship,but not the positioning,tolerance,datum in assembly.In this paper,by establishing the assembly dimension path map,the size of parts,assembly benchmarks and tolerances are all taken into account,and the information of the path formed by the target size in the path map is extracted to establish the full-correlation dimension model.Full-correlation dimension model is a functional representation of other dimension changes caused by one dimension change.The dimension model can clearly show the change of one or more dimensions associated with certain parts in an assembly when some dimensions change.It can accurately determine the dimension associated with the target dimension and the benchmark of the size of the part to which it belongs.It is more realistic.Now parametric design is necessary.The main contents of this paper are as follows:(1)Aiming at the problem of misselection of target size,a method of eliminating non-target size is proposed,and the problem of multiple selection of target size is studied.(2)A new simplified grading principle is proposed for the dimension of complex assembly.A parametric dimension-driven model is established through an example,and the analysis and calculation are carried out.(3)Aiming at the planar dimension of assembly,the descriptive methods of elements,target dimension and angle dimension are studied.The path diagram and dimension model of planar dimension of assembly are established through examples,and the analysis and calculation are carried out.