CARBONE Digi-Tig320ACDC, Руководство оператора

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B-10 OPERATION B-10
Welder Function Summary and
Explanations.
AC Frequency.
The AC frequency only applies to the AC mode.
Standard transformer welders typi-cally have a fixed
frequency of 60 Hz which is es-sentially the line input
frequency supplied by the power company. But with
inverters, the capability of AC frequency adjustment is
practically limitless due to the IGBT components that
create its own frequency. Frequency adjustment
capability is use-ful to help improve directional control of
the arc, and to focus the arc so that a narrower bead
profile can be achieved. Also, at higher frequencies, the
puddle agitation is greater which improve the breakup of
undesirable oxides. All wave forms can be adjusted
from 30-250 Hz
。
AC Balance.
The AC output is formed by rapidly alternating polarity
between electrode negative and electrode positive,
creating something that resembles a wave when viewed
on an oscilloscope. Normally, with standard transformer
welders, both standard sine wave and even square wave
weldershave little or no way to change the ratio of EN to
EP, which results in welding with a molten ball at the tip
of the tungsten and a less stable arc. Electrode
nega-tive (EN) provides penetration in the TIG welding
pro-cess. Electrode positive (EP) creates a strong reverse
flow of electricity that breaks up the weld-resistant
oxidation that covers aluminum and magnesium
com-ponents. It also places a lot of heat on the tungsten.
In a “balanced” wave where both EP and EN are equal in
time length (50%), penetration is reduced and
over-cleaning results in wide etch lines running parallel to
the side of the weld. Not all welds conditions will be
alike so more cleaning is required at times than others.
Similarly, more penetration will be required at times than
others. Ordinarily, about 30-35% electrode posi-tive is
considered an ideal amount (65-70% electrode negative).
This means that more heat is put into the work than on
the tungsten and a sharper point can be used. Cleaning
is still sufficient at that level. Good re-sults can be
achieved with about 30% EP or less. The cleaning action
is still significant even at these levels. Ideally, the
cleaning action should be adjusted until a small amount
of frosting can be seen no more than 1/8” distance from
the edge of the weld. If a piece of metal is particularly
heavily oxidized or dirty, more cleaning action will be
required. If too much cleaning action is used, the
tungsten will begin to ball and even may start to burn
away. If this much cleaning action is truly needed, then
switch to a larger sized tungsten that can handle the
increased heating level. Signs of too little cleaning
action while welding aluminum are sooty, black or dull
looking welds. A dedicated stain-less brush and
suitable aluminum cleaner such as ace-tone should still
be used before welding any type of aluminum to help
break up the heaviest oxide layer so less EP is needed
and better penetration can be achieved. Even if the
aluminum has a mirror like shine, it is still oxidized.