1.Introduction

2.Modular structure

3.Knowledge base

4.Case study

5.Conclusion & discussion

1.1Cutting and punching are two frequently applied processes in the sheet metal manufacturing industry.

1.2In order to make full use of such combination machines, a supporting CAD/CAM system is indispensable

1.3In this paper, we present an integrated knowledge-based system for sheet metal cutting-punching combination manufacturing

2.1. Modeling module

2.2. Nesting module

2.3. Process-planning module

2.4. NC-programming module

2.5. Simulation & reporting module

 Refer to the attachment <Fig.0>

The whole system consists of five functional modules, i.e. modeling, nesting, process-planning, NC-programming and simulation & reporting module. These modules share an unified objected-oriented data structure of sheet metal parts, based on which, the system is integrated seamlessly in terms of data processing.

3.1. The Nesting Rule Base (NRB)

3.2. The Optimization Algorithm Library (OAL)

• Sheet metal nesting algorithm
• Punching tool sequencing algorithm
• Cutting sequencing algorithm

3.3. The Process Rule Base (PRB)

Refer to the attachment <Fig1.gif>

Based on the knowledge base, the whole integrated system runs in an efficient and intelligent manner, starting with part modeling and ending with part processing on the machine.

- Two punching-cutting combination machines (i.e. the 647ATC and 3500ATC both made in USA) are used to process sheet metal parts for the cabs of construction machinery.

- To process 10 sheet metal parts (material = Q235, thickness = 2mm) in the stock-sheet sized 2000mm×1250mm.

Please refer to the attached image file <Fig2.jpg>

The nesting algorithm for irregular shape parts is applied for the automatic nesying, The material utilization ratio is 78.3%.

There are 3 types of punching holes, whose punching order is marked by the number in the figure.

Please refer to the attachment <Fig3.gif>

where the numbers in order indicate the contour cutting sequence, and the capital ‘C’ or ‘A’ following a sequence number denotes the cutting direction of the corresponding contour: ‘C’ for clockwise and ‘A’ for anti-clockwise.

Refer to the attachment <Fig4.gif>

The NC code generation and processing simulation for the case study.

The machine employed in this case is the 3500ATC. By processing simulation, the system reports the expected punching time 4.915min, the expected cutting time 14.399min and the expected total processing time 19.314min.

1.In order to make full use of the cutting-punching combination machines, a supporting CAD/CAM system, which is integrated and knowledge-based, is developed and successfully applied in sheet metal plants.

2.Compared with other conventional approaches, the presented system is expandable without too much programming effort, thanks to its independent knowledge base.