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Scientific Research
by Réal Girard
Herb Séguin's laser isn't the death ray
of science fiction . . . but it's close. It is by far the
biggest in Canada and can cut through 2 1/2, inch thick
steel at the rate of 200 inches a minute. What it has been
designed for, however, is just the opposite welding; more
specifically, for welding the thousands of miles of pipeline
that will be needed to bring Canadian petroleum to consumers.
Laser welding is faster and better than conventional arc
welding, says Séguin, an electrical engineer at the
University of Alberta. In conventional welding, a bend of
metal is melted into a V shaped channel along the joint
to be sealed. In laser welding, the metal edges are cut
off square and butted together, and the laser is focused
on a spot halfway through the joint. Like a white hot needle,
the beam moves along the joint melting and vaporizing a
thin layer of metal that solidifies behind the beam. The
whole process is over very quickly, so the pipe does not
heat up as it does in conventional welding, and that cuts
down stresses that might crack the weld.
The secret of Séguin's laser is his patented method
of pumping energy into the beam, which involves flashes
of ultraviolet light and surges of electric power. The result
is a relatively compact device that can be mounted on a
three ton truck, and costs the same or less than that of
conventional welding and much lower than that of any other
high power laser. The current output is better than four
kilowatts, and Séguin is gradually working the laser
up to its full power of 20 kilowatts.
A large Canadian firm has expressed interest in the Edmonton
engineer's device.
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