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The following is the hole class created byUG/KF. If the attribute parameters of the class are valued,the object or instance of the hole is confirmed concretely.Others can also be expressed similarly.DefClass: pdcapp_hole_feat(ug_base_part); # name forhole feature class(string modifiable parameter) hole_id: “variable”;#name of hole.(integer modifiable parameter) hole_type: variable;# the typeof hole.(string ) geomtry_id: “udo_name”; #reference name ofedges group.(string ) parent_feature: “feature name”; # referencename of parent feature.(number) radius: askholeradius (hole_id:); #get valuefrom function.(integer modifiable parameter) tolerance: variable;# tolerance level.(Number modifiable parameter) part_Thickness: numbervariable;(string modifiable parameter) material:”material_name” ;(list)parameter_material:@{rec:moveFirst:();rec:GetRecord:()};#ask material property from database(integer)feature_control:variable;# level of processplanning state.............# the following is a function passed from C function. Thefirst variable is the hole id; the second #oneis the libraryname of KBE; the third is the name of C function. The endof the function is the #variable type of the output value.Defun:askholeradius(string $name; String ($lib;“pdcapp_kbe”) String ($name; “PDCAPP_KF_ask_hole_radius”)) @{ CFunc(“ "UF_KF_invoke_user_function”;“libufun”);}number;(Child) db: { Design; ug_odbc_database; dsn;“pdcapp_db”;}; # create child connection between vari-able of database and database Material.(String) query: “select parameter_material” + “ " fromMaterial where Stringr = “+ “ "’” + “material_name”+“ "’”;#record query sentence: query propertiy of given mate-rial_ name.(Child) rec: { Design; ug_odbc_recordset; database;db:; sqlStatement; query: }; #create child procedure forrecord query.............** Incidentally # - declarator: the letters after it are theillustration for relevant sentences or functions.The “feature_control” above is an extraordinary param-eter for PCS to make tracks for process states, for example:0—only stamping feature; 1—operation feature havegotten; 2—process routes success; 3—stamping featureassigned to relevant work-piece; 4—work-piece designed.The whole product knowledge is represented by frameswhich directly map to objects (or features) in the object-oriented sense. Hierarchical abstraction is effectivelyexploited in modeling and representing the relationshipand constraints. The structure of a product is represented bythe stamping feature as the constructive element (or basicnote). The first layer of the construction for form features isthe main feature of the product. Other stamping featuresthat are attached to the main feature are termed as auxiliaryfeatures, making up the second layer of form features. In asimilar manner, the third layer form features are attached toFig. 3 Stamping features of automobile panel the second layer form features, and so on. For example,shown in Fig. 4 is the hierarchical structure model for thepart shown in Fig. 3.4.2 Operation featureAccordingly, stamping operation features are categorizedinto initial and subsequent, such as drawing, bending,flanging, trimming, hemming, re-striking, piercing and soon.
The relevant appropriate operations are assigned toform stamping features of products based on feature-operation criterion, parameters of the stamping feature andtheir correlativity. This assignment is a decision-makingactivity using a set of rules with decision-making tree andmodel-based reasoning methods. For example, drawing →trimming is reasoning from the main draw feature, flangingis reasoning from the flange feature, and piercing isreasoning from the hole. Fig. 5 show the typical illustrationof flanging operation features reasoning from its stampingfeature, and the sequence rules of these operation featuresare attached to the operation features.Customarily, relationships between features, especiallythe hierarchy, should be an important factor, while theoperation feature is the reasoning. In Fig. 4, the featuresflange3, flange1 and bead1 should be in the form of a settogether to deduce relevant appropriate operations. In thisway of reasoning, the operation features can get funda-mental knowledge for subsequent planning.In this paper, the operations features reasoned fromstamping features are represented as object-oriented enti-ties and UG/UDO, and the relationships are expressed asnetwork based on the stamping feature model of the product(shown in Fig. 6). The operation features not only referthemselves to stamping features, but also relate to otheroperations, such as relevant forming dies and machinerywith the relationships among them. The relationshipsbetween operations consist of operations order constraintand operations combination constraint. Another type ofrelation between processes and machines/dies is preference(preferred-to). For example, flanging is always preferred toflanging die and relevant press machine, while trimming isalways preferred to trimming die and press machine. ALLthese constraints and relationships among them are repre-sented as attributes, rules and methods in the operations. It isthrough the citation of stamping features that the descriptionof the geometrical objects are realized in the operationfeatures; while the relevant dies and machinery can berepresented in operation by options and the constraintsexpressed as relevant rules, functions or methods.4.3 Process information model (PIM) for pathplanningNow the PIM of process planning can be defined as thefoundation to process planning. And the PCS of IMM iscreated to control and monitor the stamping feature and itsoperation features by the control variable or state variable.The process planning of large complicated stampings isa dynamic process.