(1) Representations for all knowledge。

(2) Reasoning based on all this knowledge。

(3) Appropriate operation features acquired from stamping features and process rules incorporated with form- ability analysis。

(4) Process routes based on process sequencing and process combination knowledge。

(5) The control or management of process procedures for rapid response to all changes。

3 Framework of a CAPP system

3。1 The integrated master model for a CAPP system

To solve all corresponding problems mentioned above, the integrated ma ster mode l is advanced at the system level t o control and frame t he CAPP system for automobile panels。 I t is a common concept and framework to generalize and specialize the function, course control , process planning circumstance, and act iv it ies involved in t he development o f an integrated and intelligent system into abstract groups, and to make t he m carry out all contents and processes。 This mode issue table for knowledge expression and application, process controlling, information integration, change response , etc 。The intelligent master model (IMM) of stamping process planning for automobile panels is composed of a knowledge base, process control structure (PCS), process planning optimization (PPO), process information model (PIM), and linkable environment (LE), which are integrated and combined based on KBE。 The structure of the IMM is shown in Fig。 1。 The IMM of process planning is

not only the foundation of intelligent CAPP for automobile panels, but also the integration of knowledge and methods, which combines the KBE system with the process planning。 With this model, KBE acts as a knowledge source to drive PCS, PIM, and LE, which makes process planning integrated and associative。 The PIM is a dynamic expanded information model, in which the information can be added and updated along with process planning。 Using knowledge multi-expression format, the integrated information model of process planning is built based on a feature model。 For the hierarchy and framework of the features, semantic net and object- oriented methods are adopted to express knowledge and establish an information  model in which process knowledge, e。g。 database, parameter, rules, and experience, act as rules and attributes of the objects, and where whole product knowledge acts as a framework for relationships of objects。 With a process information model, the process planning can be completed through knowledge-reasoning and decision-making based on knowledge encapsulated in the objects。 The PCS is a key point to ensure process planning is integrated and consistent; it manages the process information model, process planning to generate stamping process plans and detail design, and controls the changes of the planning。 In IMM, the PCS comes into being dynamically along with the process planning。 If one part of PCS is created, it will monitor and control relevant planning and information subsequently。 When results of process planning are

deleted, the corresponding PCS part will fade away accordingly。 The LE provides several methods to deal with the links among process planning procedures, the geometry between product and detail design of work pieces。 To achieve intelligent process planning for large complicated stampings, there are problems to solve, i。e。 linking of process planning procedures, the geometry link between product and detail design of work pieces。 The LE provides several methods to deal with these links, e。g。 parameters variable link, data structures link, and geometrical link。 The PPO is a methodology of design optimum for complex engineering, which can deal with the complicated optimization problem of process planning in an economic view。