Advertisement
TH
TIWIN iCAR
B O N I:A R C TO R C H
-[
CAH_ON ELECTRODES
CONNECTTO
SCREY+VS
6ROUHt] AND ©
F+IJF+CTR
ODE
CABLESOF
EI.ECTROOETIPS
A. C+WEILOER
Figure
I
Work ordinarily
done with a gas welding torch is possible
with the twin-carbon
arc torch connected to an A.C. welder.
The carbon-arc
flame is similar to the flame of a gas we]d_
ing torch in that it provides heat by radiation,
rather than
by direct arc between work and electrode. This flame heat
greatly
widens the scope of work possible with the arc
welder for brazing, soldering, welding of non-ferrous metals
and localized heating for bending, forging and hardening.
The arc torch (fig. 1) consists of an insulated handle with
two projecting carbon electrode holders, one of which is ad-
justable to permit striking and breaking an arc at the carbon
tips, A thumb knob on the handle performs the adjustment
and Operates a shut-off switch built into the handle. There
To prepare
the torch for use, connect
its two cables
to the
ground
and
electrode
cables
of
the
welding
machine.
Grounding
of the work is not necessary as the operation
of
the arc flame is entirely
independent.
With the thumb knob
on the handle
in the !'off"
position,
insert two 3/8-inch
car-
bon electrodes
in the holders
and damp
in pIace at approxi-
mately
one-half
their length
(fig.
2). Do not clamp
them
on or near the ends opposite
from the arc as this will cause
Overheating
of the carbons.
When
tightening
the clamping
screws, be careful
not to apply
too much pressure
on the
carbons,
as they are very brittle and break easily.
Use only
enough
pressure to hold
them firmly
in p_ace. If the tips
of the carbons do not line up with each other,
an adiustment
may be made by turning the longest of the electrode
holders
slightly;
too much turning will loosen it, and make
it neces-
sary to disassemble
the torch to again
tighten
it properly.
Do not make any turning adjustments with the sliding holder
as this would spoil the contact tension in the switch.
To strike the arc, turn on the welding
machine
and set it for
approximately
70 amperes.
Lower the welding
helmet
and
hold
the torch up to silhouette
it against
the light
of a win_
claw.
Slowly
move
the thumb
knob
forward
until
contact
is made
between
the tips of the carbons.
This wifl
start the
arc. Then immediately
move
the knob
back to increase
the
gap between
the carbons.
The actual
distance
can be deter-
mined
with a little practice.
When
the carbons
are too close
the
arc flame
will
have
a sharp
crackling
noise.
As the
distance
between
the carbons
is increased,
the crackling
will change
to a soft purring
sound which
indicates
the best
::
are
na valves
or: gauges
that:require
fine
adjustment
as
arc flame.
There are
two heat
zones
and
the small
inner
i_:::
i ::withan oxyacetylene:torch_
The sam e pr0tectlve
equipment
z.one Lsby far thehottest,
hav!ng
an estimated
temperature
at yuuu cfegrees
ranrenne_r
Lng .3)
::: i
na:rya:rC
welding::is:usedWhehoperatingthe
'
"
::::
i:i:
:
:::;i::i=i:
::i
iii: i
The shape
Of the flame
greatly
influences
theWay
in which
: :I:A: wide
Selection:lot
flame
heats
may be:iha:d:
,t, mus _:ibel. US ed?i
°nvbeveled
f_a_:
twhi; ;:ar_hh
the_Current
and
size of the Carbon
: Sn°U_a: bene!aPara!!e!
t ° ! e gr: o e so:the
.
:
acfuai
temperature
of
the bottom
(!Ig,
r'cghtLahg_es t twOiltlheo?r:eOV
_ _h_
current
seffing;
the Volume 0f transferable
heat:ir_creaSes
:
flame
straddles th e groo
e a
_with
an
increase
in :arn'perage.
However;
amperages
in :
bottom
(fig: 5). Filler rod s, as for gas welding,
must be used
:e_CesS0f thoseglven
belbw will Onty cause Short Carb0_
life.
On joints
at this: type.:.
1/4-ira
carbons:_;.:;:..,
i, .!L30
to40
amperes
The soft, bushy flame
is pressureless and
has no tendency
: 5/16-in.
carbons.:_:!.';
!_.
_!40
to65
amperes
to blow
the molten
metal
This is a distinct
advantage
when
3/8-in.
carbons.
65
to 90 amperes
welding
thin sheet metal.
Joints on light
material
should
be
i ii
iii iiii
II iiii
III !ll iii
Figu_'e
2
i
H
i I I
III i[ I
/
Figure 3
L
Cg_RECT
FLAME
POSITION
F_gure
4
iu ........
L_
,
i
IHI
INCORRECT
FLAME
POSITION
Figure
5
,11_
..
1_16
Advertisement
