Parameterization Design And Automatic Assembly Of The Planar Linkage Mechanism

Parametric design and automatic modeling of the planer linkage parts and their automatic assembly have been studied,the parameter specifically for parametric design of parts can only realize change whose dimension characteristics,but having no way to realize the parts section shape change, being aimed at this one phenomenon,there brings forward one kind of the parametric design procedures assisting the criterion characteristic.Adopt this method,the father-son relationship should be created between the benchmark assisted features and the composed of the part shape features,moreover can realized the change of the parts section shape.With the method of automatic assembly the modeling of similar parts can be finished quickly and exactly. The identification of parts fit features and the benchmark assisted features of fit features and the discrimination of matching relationship are studied mainly as the object of automatic assembly.In the automatic assembly,the fit features are come from parts or from the benchmark assisted features which created reference the parts feature,therefore,the benchmark assisted and the parts features are coexistence relationship;how to separate the benchmark assisted from the parts fit feature,and ensured the rationality assembling.There are puting forward a method about automatic assembly which based on benchmark assisted features,this method not only simplified the identification of parts fit features and the benchmark assisted features of fit features and the discrimination of matching relationship,but also realized easily the judgment of assembling-possibility and the detection of assembly interference, furthermore,the mechanism which finished with the method can be achieved the parametric design of mechanism.The characteristics of parametric design is feature-based,full-size constraint,all-associated data and dimension driving,with the characteristics of parametric and correspondence with corresponding relation which is set membership in building model process introduced in detail the criterion of benchmark assisted features in this paper,and introduced how to establish the relationship constraint and dimension constraint between the parts features and benchmark assisted features.There are classified the parts for the planar linkage and analyzed the corresponding relation among the features of planar linkage,there are also introduced how to create the benchmark assisted features on the parts of planar linkage,and adopt the frame model create the parts of planar linkage.There should storage the information of parts and dimension information,features information,tape information of the fit features with the using of database;Providing the interactive interface and the part model about the parametric design and automatic assembly,and giving the brief description of them.In order to identify easily the location datum of the fit features of parts, the location datums of the fit features have to be separated from the parts model and single expression using the benchmark assisted features when applied the method which is adopted benchmark assisted features in automatic assembly and combined with the benchmark assisted features in parametric design and automatic modeling of parts.Dimension relationship is set up between the position dimension of the fit features and the position dimension of the benchmark assisted features,the connection is also created between the database with the shape dimension,geometric features,tape features.Two methods about automatic assembly and semi-automatic assembly are applied in the mechanism of the planner linkage and each method has its characteristics and application scope,providing the interactive interface and giving the brief description of them.The method about mechanism parametric not only can realize dimension of mechanism alteration but also can change the section form of fit features in the mechanism.The cooperative relation would not be changed when transformed the section form of fit features or altered the dimension of parts, so it is able to ensure assembling rationality.In this paper introduced how to realize the mechanism parametric and the realization process of mechanism parametric with the example of eccentric wheels mechanism.