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68 Fraunhofer Institute for Laser Technology ILT, www.ilt.fraunhofer.de
DQS certified by DIN EN ISO 9001, Reg.-No.: DE-69572-01
Sub
ject
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erat
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ecifi
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tec
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. 06/
2011
.
532 µm
2
1 Beam control component for integration
with process monitoring.
2 Coaxially imaged cut gap.
task
Lasers are an established tool for cutting stainless steel sheet
and plate. Production systems with CO2 laser beam sources
have particular strengths for cutting heavier-gauge plate and
rapidly producing contours on flatbed machines. Reliable
process control for the necessary product quality, however,
requires information about the current working point of the
process. A process sensor system therefore has to provide
relevant measured variables for active closed-loop control.
Method
In the cluster of excellence at RWTH Aachen University
research scientists from Fraunhofer ILT are working on the
development of a sensor system which observes the laser
cutting process coaxially through the cutting head. From
the signals measured, variables are extracted which make
it possible to determine the working point of the process.
This information is subsequently used for self-optimization
of the cutting process.
Result
The sensor setup for CO2 laser cutting consists of two com-
ponents: an optical system with an area sensor and a system
for image processing. The optical system couples process
observation coaxially into the beam path of the laser and
projects the zone of interaction through the focusing optic
onto the sensor. By subsequent signal processing variables are
extracted which enable a conclusion to be drawn as to the
working point of the process. One of these variables is the gap
width, which as a function of further parameters permits a
conclusion to be drawn about the focus position.
For the purpose of self-optimization the signal processing
function is extended to extract numerous variables using
multiple algorithms. In combination with process modeling,
a method has thereby been established to comprehensively
determine the working point, enabling self-optimization of
the process.
applications
The process sensor equipment has been installed in an indus-
trial production system. Together with model-based analysis
of the measured variables, quality-relevant information is
extracted which is used to control the process. The system is
being transferred to other production processes on the basis
of corresponding process models.
contacts
M.Sc. Dipl.-Ing. (FH) Ulrich Thombansen
Phone +49 241 8906-320
Dipl.-Ing. Peter Abels
Phone +49 241 8906-428
sensors for Laser cuTTIng
1