GT POWER GT200W, Руководство по эксплуатации

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GT200W
PROFESSIONAL WELDER GENERATOR
20. 21. www.gtpower.co.nz www.gtpower.co.nz
20
o
1.6mm (1/16”)
Striking an Arc
(Fig 1-20)
Arc Length
The securing of an arc length necessary to pro-
duce a neat weld soon becomes almost automatic.
You will find that a long arc produces more heat.
A very long arc produces a crackling or splutter-
ing noise and the weld metal comes across in
large, irregular blobs. The weld bead is flattened
and spatter increases. A short arc is essential if a
high quality weld is to be obtained although if it is
too short there is the danger of it being blanketed
by slag and the electrode tip being solidified in. If
this should happen, give the electrode a quick twist
back over the weld to detach it. Contact or “touch-
weld” electrodes such as E7014 Stick electrodes
do not stick in this way, and make welding much
easier.
Rate of Travel
After the arc is struck, your next concern is to main-
tain it, and this requires moving the electrode tip
towards the molten pool at the same rate as it is
melting away. At the same time, the electrode has
to move along the plate to form a bead.
Making Welded Joints
Having attained some skill in the handling of an
electrode, you will be ready to go on to make up
welded joints.
A. Butt Welds
Set up two plates with their edges parallel, as
shown in Figure 1-21, allowing 1.6mm to 2.4mm
gap between them and tack weld at both ends. This
is to prevent contraction stresses from the cooling
weld metal pulling the plates out of alignment.
Plates thicker than 6.0mm should have their mat-
ing edges bevelled to form a 70º to 90º included
angle. This allows full penetration of the weld metal
to the root. Using a 3.2mm E7014 Stick electrode
at 100 amps, deposit a run of weld metal on the
bottom of the joint.
Do not weave the electrode, but maintain a steady
rate of travel along the joint sufficient to produce a
well-formed bead. At first you may notice a tenden-
cy for undercut to form, but keeping the arc length
short, the angle of the electrode at about 20º from
vertical, and the rate of travel not too fast, will help
eliminate this.
Tack Weld
Butt Weld
(Fig 1-21)
Electrode
20
o
- 30
o
Tack Weld
by scratching the electrode along the plate surface
in the same way as a match is struck. As soon as
the arc is established, maintain a 1.6mm to 3.2mm
gap between the burning electrode end and the
parent metal. Draw the electrode slowly along as
it melts down.
Another difficulty you may meet is the tendency,
after the arc is struck, to withdraw the electrode so
far that the arc is broken again. A little practice will
soon remedy both of these faults.
The electrode is directed at the weld pool at about
20º from the vertical. The rate of travel has to be
adjusted so that a well-formed bead is produced.
If the travel is too fast, the bead will be narrow and
strung out and may even be broken up into indi-
vidual globules. If the travel is too slow, the weld
metal piles up and the bead will be too large.