Abstract
High quality laser welding is achieved under the condition of
optimizing all process parameters. Assisting gas plays an
important role for sound welds. In the conventional welding
process assisting gas is used as a shielding gas to prevent that
the weld seam oxidates. In the laser welding process assisting gas
is also needed to control the laser induced plasma.Assisting gas
is one of the most important parameters in the laser welding
process. It is responsible for obtaining a quality weld which is
characterized by deep penetration, no interior imperfections, i.e.
porosity, no crack, homogeneous seam surface, etc. In this work a
specially designed flexible off-axis nozzle capable of adjusting
the angle of the nozzle, the diameter of the nozzle, and the
distance between the nozzle end and the welding zone is tested. In
addition to the nozzle parameters three gases, Nitrogen, Argon,
and Helium are applied with three different flow rates for each of
the gases. A number of systematic laboratory experiments is
carried out by employing various experimental designs, 33 and 32
Factorial Design. In the experiments a CO2 laser is used to weld
thin sheets of mild steel. The welding specimens are evaluated by
a number of quality characteristics, such as the seam depth and
seam width. The significance of the gas parameters and their
interactions are based on the data found by the Analysis of
Variance, ANOVA.In order to investigate the possibility of
automatic optimizing the welding process, a couple of photo diodes
are applied to monitor the welding process. These two photo diodes
are arranged in two different viewing angles. The couple of photo
diode signals are translated by a data acquisition card and stored
in a computer. The photo diode signals are further analyzed with
FFT frequency analysis. The relations between the gas parameters
and signal frequencies are studied. Finally the relationships of
the gas parameters and weld characteristics are studied. The
possibility of using photo diode signals in controlling the gas
parameters is discussed.KeywordsCO2 laser welding, assisting gas
parameters, factorial design, photo diode signals.
| Original language | English |
|---|---|
| Title of host publication | Proceedings 6th Welding |
| Place of Publication | Nagoya |
| Publisher | Kyroki Publishing Co. |
| Publication date | 1996 |
| Publication status | Published - 1996 |
| Event | 6th Welding Society - Nagoya, Japan Duration: 1 Jan 1996 → … |
Conference
| Conference | 6th Welding Society |
|---|---|
| City | Nagoya, Japan |
| Period | 01/01/1996 → … |