Flxible dieless manufacturing system of multi-point press forming and stretch forming.

Su, Shizhong ; Pham, Duc Truong ; Li, Mingzhe 等

Abstract: Multi-point forming (MPF) technology employs adjustable punch matrices. Dieless manufacturing system of dieless multi-point press forming and multi-point stretch forming is a flexible manufacturing system for automatically forming of 3D surface parts. During forming process, each of punches can be controlled by robotic devices to adjust its coordinates for shaping discrete 3D tool surfaces. Based on the principle, two prototypes of dieless manufacturing system are being been developed. The system integrates the technology of MPF with the technology of computer aided. The paper introduces the principle and mechanism of multi-point press forming and multi-point stretch forming. It describes the construction of dieless manufacturing system in details. The paper gives some experimental results of 3D surface panels.

Key words: Multi-point forming, flexible manufacturing, 3D panels, CAD/CAE/CAT.

1. INTRODUCTION

Many scholars and researchers from Asia and U.S.A have studied on new technologies of dieless forming as some disadvantages in traditional solid die forming. Reconfigure die forming (R. D. Webb & D. E. Hardt, 1991) and multi-point forming (Li M. et al., 1999) technologies have been proposed. Some experimental apparatuses and machines have been developed.

However, there are some key technological problems need to be solved for automatically forming large complex aircraft panels.

2. DIELESS MULTI-POINT FORMING METHODS

Dieless MPF tooling employs adjustable punch matrices without using the traditional solid dies. During the forming process, each of punches can be controlled by computer control system (CCS) to adjust its coordinates to shape discrete three dimensional tool surfaces.

Generally, there are two types of punches used in MPF tooling, i.e. the fixed punch and the mobile punch. The fixed punch is adjusted to proper position before forming and not adjusted during the whole forming process. The mobile punch is drove from up and down.

With the change of the relative positions of punches during the forming process, deformation path and stress distribution of parts can be changed, which affects the quality of forming panels.

2.1 Multi-point press forming

Multi-point press forming employs two sets of punch matrices with traditional press machine. Using two types of punch above separately, the two forming methods are easily applied into industrial production, i.e. fixed multi-point press forming method and mobile multi-point press forming method (see Fig. 1 and Fig. 2).

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2.2 Multi-point stretch forming

Multi-point stretch forming employs one set of punch matrix with traditional stretch machine. Fixed multi-point stretch forming and mobile multi-point stretch forming are typical forming methods (see Fig. 3 and Fig. 4).

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3. FLEXIBLE MANUFACTURING SYSTEM

The flexible manufacturing system consists of hardware of forming press, robotic control unit, laser CMM and integrated software of CAD/CAE/CAM/CAT (see Fig. 5). The system is perfectly flexible system because high technologies of computer, FEM simulation and robotic control are applied to the whole manufacturing process from surface modelling and numerical simulation to deformation and measurement.

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3.1 CAD/CAE software

The integrated CAD software is to model the 3D product and output 3D surface data according to the shape and material required. The CAE software also predicts the final results and defects with the elastic-plastic FEM (see Fig. 6).

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3.2 Robotic control unit

Robotic control unit adjusts the upper and lower punch matrices in serial or parallel adjusting mode to shape tool surfaces according 3D data output by CAD/CAE software.

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Based on the principle above, two prototypes of multipoint press forming and multi-point forming tooling are being designed and manufactured within the DATAFORM project.

4. EXPERIMENT RESULTS

The flexible manufacturing system, MPF press have been manufactured by Jilin University (JLU), has been applied to manufacture many products in 3D panels of vehicle and high-speed streamline train, skull implant and large sculpture (see Fig. 9).

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5. CONCLUTIONS

A flexible dieless manufacturing system of multi-point press forming and multi-point stretch forming tooling will be developed within EC-granted DATAFORM project. The dieless forming system will cut down so tremendous expense cost and long time for manufacturing solid dies and improved the deformation condition and minimize spring-back of 3D aircraft panels.

6. ACKNOLEDGEMENTS

The DATAFORM project is funded by the European Commission under FP6 in the area of Aeronautics (contract No. 030877).

7. REFERENCES

R. D. Webb & D. E. Hardt, (1991). A Transfer Function Description of Sheet Metal Forming for Process Control, Journal of Engineering for Industry, No.113, pp.44-52.

Li M., Liu Y. & Su S. (1999). Multi-Point Forming: a Flexible Manufacturing Method for a 3-D Surface Sheet.Journal of Materials Processing Technology, No. 87, pp.277-280.