Learning To Weld; Arc Welding Circuit - Lincoln Electric LTW1 Manual De Instrucciones

LEARNING TO WELD

LEARNING TO WELD
Welding is a skill that can only be learned by practicing. No
one can become an accomplished welder simply by reading
about it. The following pages will help the inexperienced
operator to understand the basics about wire welding and
provide guidance to help develop this skill. For more
detailed information, order a copy of "New Lessons in Arc
Welding".
THE ARC-WELDING CIRCUIT
The operators knowledge of arc welding must go beyond the arc
itself. The operator must know how to control the arc, and this
requires a knowledge of the welding circuit and the equipment that
provides the electric current used in the arc. Figure 1 illustrates the
welding circuit for a typical welding machine. The circuit begins
where the gun cable is attached to the welding machine. Current
flows through the gun cable, gun, and contact tip, to the wire and
across the arc. On the work side of the arc, current flows through the
base metal to the work cable and back to the welding machine. This
circuit must be complete for the current to flow. Loose or poor
connections anywhere in the circuit will rob voltage from the arc and
cause it to become erratic.
This machine's welding circuit has a voltage output of 32 volts DC
maximum. This voltage is quite low and is only present when the gun
trigger is pressed.
FIGURE 1
Gun and Cable
Work Piece
Work Clamp
To weld, the work clamp must be tightly connected to clean base
metal. Clean the joints by removing excessive scale, rust, moisture,
paint, oil and grease from the surface. As with all welding appli-
cations, joint cleanliness is necessary to avoid porosity and to attain
the best weld quality. Connect the work clamp "as close as possible"
to the area you wish to weld. This helps prevent current from going
through an unwanted path. Avoid allowing the welding circuit to pass
through hinges, bearings, electronic components, or similar devices
that can be damaged. See Figure 2. Always disconnect electrical
devices before welding upon them.
FIGURE 2
Bearings
Hinges
WRONG WRONG
CURRENT CURRENT
P P A A TH TH
CORRECT CURRENT CORRECT
P P A A TH
* For best results position work clamp approximantely
12 inches(294mm) from the welded area.
WARNING
Fumes and slag generated from
Innershield type electrodes
recommended for use with this welding
machine can produce fumes and gases
hazardous to your health.
• Avoid contact with eyes and skin.
• Do not take internally.
• Keep slag away from children.
• Keep out of reach of children.
• Follow all safety precautions found in your operator's
manual.
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The gun and cable assembly is held by the operator, who guides the
automatically fed wire along the joint, maintaining a contact tip to
work distance of about 3/8" to 1/2" (10 – 12 mm) This is called
Contact Tip to Work Distance. The welding arc is established in the
gap between the work and the end of a small diameter wire. When
the power source is properly set, the length of the arc is maintained
automatically.
Arc welding is a manual skill requiring a steady hand, good physical
condition, and good eyesight. The operator controls the welding arc,
and therefore the quality of the weld made.
2
Electrical Components
*
CURRENT
TH