by PPO based on KBE.

Fig. 8 Sequence planning of operations

Process Knowledge Reasoning Rules of operation combination … Artificial Neural Networks

Rules of Precedence …

Stamping feature

Operation feature

Initial main operations sequences

auxiliary operations

Operations combine & orders

Process routes & Relevant die

Main draw Flange2 Flange1 Flange3 Bead1 Emboss Hole2 Hole1 Hole3 Flange4 Bead2

Bead3 Bead4 Bead5

 DR    TR BL

FL

FL +FM     FL DR

FM    PRC

TR

PRC PRC

FL FL

         FM FM FM

PRC (3)

FM (6)

DR + FM

TR + PRC

FL + FM

BL (Shearing for blanking)

DR+FM ( main draw + emboss

+ bead2+bead3+bead4+bead5)

Drawing die

TR+PRC (Trimming boundary of draw

+ hole1+hole2+hole3 ) Compounded die for TR&PRC

FL+FM (Flange 3 + Bead1) Flanging die

FL (Flange1+flange2+flange3) Flanging die

Supplement: BL—Blanking; DR—Drawing; TR—Trimming; FL—Flanging; PRC—Piercing; FM--   Forming

Fig. 9  The decision route of process planning for one automobile   panel

4.5 PCS in process path generation

Since the process planning is a dynamic course with several plans and design stages, PCS is a key point to ensure process planning is integrated and consistent. PCS man- ages the process information model, assists in generating stamping process plans and detail  design,  and controls the changes during planning. There are several control variables for PCS including state variables for process planning, control variables for IMM, and state variables for stamping features, etc. The process control structure is shown in Fig. 10.

In this CAPP system, the process planning is defined as a project. The project control can create a project, insert the part or work-pieces to suitable positions of the project, and decompose the process planning task into subtasks.

In IMM and process planning, according to the knowl- edge expression and decision-making rules, the planning process control can set up the process information  model

Fig. 10  The process control  structure

based on features and their state variable, monitor planning process, feed the planning information and changes back to IMM, and control information transfer.

The process planning is a dynamic process of informa- tion flow and transfer. The information link control ensures process planning information is associative and consistent. The added, extended, and modified information and its effects on the planning can be fed back to PIM and IMM so that the information of process planning can be updated timely and shared by different parts of the system.

For the complicated and mass geometry information involved during the process planning, the links between features and product geometric information have been dealt with. The geometry link control can monitor and control the links and transfer the geometry information between different parts of the process planning.

In IMM, the parts of PCS come into being dynamically along with proceeding of the process planning. If one part of PCS is created, it will monitor and control relevant planning and information subsequently. When some results of process planning are deleted, the corresponding PCS part will fade away.