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Multi-sensor system for in-die process quality assurance at forming machines

The objective of the research project was the process monitoring of multi-stage tools for blanking, bending, forming and stamping on automated punching presses. A multi-sensor system was developed to combine high sensitivity to the process with good handling. For the determination of tool set-up, breakage, feeding problems or wear a combined force and acoustic emission monitoring system was developed.

The sensor plate is a modular plate consisting of:
multiple normalised sensor cassettes, which include force or acoustic emission sensors;
two guiding rails and a frame plate, which is adapted to the ram size of the press;
a docking station with pre-processor electronics to amplify the sensor signals.

This modular style of the plate allows an adaptation to the press and tools of the user. The number, as well as the position, of the cassettes can be adapted to the specific requirements of the user. For a new press type only the design of the frame plate must be changed. The pre-processed signals are transmitted to a signal processing unit. The basis of the signal processing unit is a Pentium processor with a newly developed PCI card. The PCI card converts analogue signals to digital signals, filters the signals, controls the amplitude of the signals according to a self learned tolerance band of good parts. The PCI card is also modular. Shuttles for the pre-processing of high frequency acoustic emission sensor signals can be jumpered on the board. The pre-processing of the signals (for example 3 force and 1 acoustic emission) is done on the card. The calculation of the tolerance band is performed as one task under Windows 95 on the PC. Also the graphical user surface is programmed under Windows 95.

Reported by

Universität Hannover
Welfengarten 1A
30167 Hannover
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