Lincoln Electric ACTIV8, Руководство оператора

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B-7
OPERATION
B-7
ACTIV8™
If the contact tip to work distance is properly main-
tained,asatisfactoryoperatingvoltagerangemaybe
achieved, and a sound weld may result. However,
when a welder uses a longer contact tip to work dis-
tance, an arc-sensing wire feeder compensates by
increasingthewirefeedspeedtoregulatethevoltage.
Evenifthevoltageandcurrentremainunchanged,the
increased wire feed speed may result in a deposition
ratewellbeyondthespecifiedrangeoftheelectrode.
Undertheseconditions,thespecifiedweldmetalprop-
ertiesmaynotbeachieved.
Constant voltage power sources deliver large current
surgestostabilizethearcwhentheelectrodeisshort-
edorthearclengthisveryshort.However,aconstant
current power source does not provide such a
response to stabilize the arc. It may be difficult to
achieverequiredweldmetalproperties,ortoachieve
therequiredqualityofweldsneededtopassnonde-
structivetests,whensuchweldsaremadeundercon-
stantcurrentoperation.
Forthesereasons,LincolnElectricdoes NOT recom-
mend constant current semiautomatic welding for
applicationswhichneedtomeetspecifiedweldmetal
chemicalormechanicalpropertyrequirementsorweld
qualityrequirements.
Constant Current
Power Source
Current
Current
Wire
Feeder
WFS
CTWD
Welding Cable
(Electrode)
Welding Cable
(Work)
GUN AND CABLE
ASSEMBLY
+
-
FIGURE B.5
CONSTANT CURRENT OPERATION
(SeeFigureB.5)
Lincoln Electric does NOT recommend constant
current semiautomatic welding for applications
which need to meet specified weld metal chemical
or mechanical property requirements or weld
quality requirements.
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Most semiautomatic welding processes perform better
usingconstantvoltagepowersources.
Weldingcodesusuallydonotaddressthepowersource
selection or specifically, whether the welding process is
tobeoperatedintheconstantvoltageorconstantcurrent
mode.Instead,codestypicallyspecifylimitationsonthe
current, voltage, heat input and preheat temperature
based on the material to be welded. The intention is to
assurethatproperweldmaterialpropertieswilldevelop.
Welding is sometimes performed using constant current
power sources. The operation can be more convenient
becauseitmayallowtheuseofanexistingstick(SMAW)
powersourceandthepowersourcecanbeplacedata
distant location without any provision for adjusting the
outputsettings.
Forconstantcurrentoperation,thepowersourceissetto
deliverthespecifiedcurrent.Thepowersourceregulates
thiscurrentregardlessofchangesintheweldingcircuit,
including cable length, electrode diameter, wire feed
speed,contacttiptoworkdistance,etc.
Changesinthewirefeedspeed(WFS)orcontacttip
toworkdistance(CTWD)affectthearcvoltagewhen
constant current power sources are used. Lowering
the wire feed speed raises the voltage, raising the
wirefeedspeedlowersthevoltage.Lengtheningthe
contact tip to work distance raises the voltage, short-
eningthecontacttiptoworkdistancelowersthevolt-
age.
CAUTION