In the laser-assisted welding with electric resistance heating of steel pipe, it was found by experiments that the incident beam profile has significant influence on the welding quality-generating defect in the weld part. We developed the simulation model for the wedge shape welding method in order to decide the most suitable laser beam profile. It is the three-dimensional heat transfer model with two heat sources, Joule heat by electric resistance and multiply reflected and absorbed laser power by the wedge walls. After confirmation of its validity by comparing model outputs with experimental data, we determined the most suitable beam profile in this welding method. Next, in order to realise the above determined profile, we designed a beam shaping optical system which consists of sperical and cylindrical mirrors. In a production line, it is required to change quickly the beam size corresponding to the size of a workpiece. Finally we provided the mirror controlling system based on the calculation of light paths tracking method.

1.
H.
Haga
and
N.
Mizuhashi
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Influence of Oscillator Frequence on the welding Phenomena in High-Frequency Electric Resistance Welding
”,
IIW III
845
(
1986
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2.
K.
Minamida
,
H.
Takafuji
,
N.
Hamada
,
H.
Haga
and
N.
Mizuhashi
, “
Wedge shape welding with multiple reflecting effect of high power CO2 laser beam
ICALEO’ 86
105
(
1986
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