(list)parameter_material:@{rec:moveFirst:();rec:Get Record:()};#ask material property from database

(integer)feature_control:variable;# level of process planning state.

............

# the following is a function passed from C function. The first variable is the hole id; the second #oneis the  library

name of KBE; the third is the name of C function. The end of 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” + “ from Material 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 for record query.

............

** Incidentally # - declarator: the letters after it are the illustration 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 have gotten; 2—process routes success; 3—stamping feature assigned to relevant work-piece; 4—work-piece designed. The whole product knowledge is represented by frames which directly map to objects (or features) in the object- oriented sense. Hierarchical abstraction is effectively exploited in modeling and representing the relationship and constraints. The structure of a product is represented by the stamping feature as the constructive element (or basic note). The first layer of the construction for form features is the main feature of the product. Other stamping features that are attached to the main feature are termed as auxiliary features, making up the second layer of form features. In a similar manner, the third layer form features are attached to

the second layer form features, and so on. For example, shown in Fig. 4 is the hierarchical structure model for the part shown in Fig. 3.

4.2 Operation feature

Accordingly, stamping operation features are categorized into initial and subsequent, such as drawing, bending, flanging, trimming, hemming, re-striking, piercing and so on. The relevant appropriate operations are assigned to form stamping features of products based on feature- operation criterion, parameters of the stamping feature and their correlativity. This assignment is a decision-making activity using a set of rules with decision-making tree and model-based reasoning methods. For example, drawing → trimming is reasoning from the main draw feature, flanging is reasoning from the flange feature, and piercing is reasoning from the hole. Fig. 5 show the typical illustration of flanging operation features reasoning from its stamping feature, and the sequence rules of these operation features are attached to the operation features.

Customarily, relationships between features, especially the hierarchy, should be an important factor, while the operation feature is the reasoning. In Fig. 4, the features flange3, flange1 and bead1 should be in the form of a set together to deduce relevant appropriate operations. In this way of reasoning, the operation features can get funda- mental knowledge for subsequent planning.

In this paper, the operations features reasoned from stamping features are represented as object-oriented enti- ties and UG/UDO, and the relationships are expressed as network based on the stamping feature model of the product (shown in Fig. 6). The operation features not only refer themselves to stamping features, but also relate to other operations, such as relevant forming dies and machinery with the relationships among them. The relationships between operations consist of operations order constraint and operations combination constraint. Another type of relation between processes and machines/dies is preference (preferred-to). For example, flanging is always preferred to flanging die and relevant press machine, while trimming is always preferred to trimming die and press machine. ALL these constraints and relationships among them are repre- sented as attributes, rules and methods in the operations. It is through the citation of stamping features that the description of the geometrical objects are realized in the operation features;  while  the  relevant  dies  and  machinery  can be