resistance of molten seam and preservation of bath. It is easy to obtain even fusing deepness.
This process is specially applicable to omni-bearing welding of sheet and formation to be done
with both sides through one side welding.
b. Heating and cooling of each welding point is very fast,.Therefore,the process is applicable for
the workpiece with great difference of heat conductivity and thickness.
c. Pulse arc can obtain greater fusing deepness with lower heat input.Therefore under the
same condition, the zone influenced from welding heat and deformation from welding can be
reduced. This is very important for sheet and ultra-thin sheet welding.
d. Fast cooling of the bath metal and shot duration time of high temperature during welding
can reduce cracks caused to the thermo-sensitive materials during welding.
③
.Selection of welding parameters
Except for pulse current and the width time (width ratio) as well as pulse frequency ,welding
parameters of pulse argon gas tungsten arc welding are as same as general tungsten DC argon
are welding. Pulse current increasing means electric arc can obtain greater penetration ability.
But too much current can cause local melting of tungsten electrode.Generally,welding current
required for DC tungsten argon are welding or greater current is used. Arc holding current and
base current influences cooling and crystallizing of the metal in the bath. The range is
determined by performance of the welding materials. When sheet is welding,smaller arc holding
current (base current) is usually used in order to reduce welding through and deformation.When
pulse width ratio (holding time of pulse current and base current) is selected, both the heat input
％
and features of pulse welding should be considered. Usually, it can be selected between 10
- 90
％
. Selection of pulse frequency (periodical change time of pulse current) mainly depends on
thickness of sheet and welding speed and operation custom of the operator should be also
considered.
1.4 AC ARGON ARC WELDING
1. selector "11" onto the position " AC TIG ",selector "25" onto the position "HF TIG",
selector "10" onto the position "off " or "Advanced AC",Connecting the gas inlet pipe to inlet "21"
of the welding.
2. The method of the connection same as 1.1
3. select right "sp(AC Balance)"
SP= *100%
tp:the time of I
2
at positive tn: the time of In at Negative
4. select right AC square wave frequency &AC balance.
tp
tn
