Telwin Technology 220 HD [7/84] Welding description of the procedure

Telwin Technology 175 HD [7/84] Welding description of the procedure
5.5 CONNECTION OF THE WELDING CABLES
should be repeated periodically, depending on the amount of use and wear of the
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electrode, or when the electrode has been accidentally contaminated, oxidised or used
incorrectly.
WARNING! BEFORE MAKING THE FOLLOWING CONNECTIONS MAKE
The following table indicates approximate diameters for the electrodes, bearing in mind
SURE THE WELDING MACHINE IS SWITCHED OFF AND DISCONNECTED FROM
that for DC welding (with the electrode on the (-) pole) an electrode with 2% Cerium
THE POWER SUPPLY OUTLET.
(grey band) is usually used.
2
Table (TAB. 1) gives the recommended values for the welding cables (in mm )
To achieve a good weld it is absolutely necessary to use the exact electrode diameter
depending on the maximum current supplied by the welding machine.
with the exact current. The electrode usually protrudes from the ceramic nozzle by 2-
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3mm, but protrusion may reach 8mm for corner welding (see TAB. 3).
5.5.1 MMA WELDING
6.2.1 Procedure (TIG)
Almost all coated electrodes are connected to the positive pole (+) of the power source;
- Holding the mask IN FRONT OF THE FACE, strike the electrode tip on the workpiece
as an exception to the negative pole (-) for acid coated electrodes.
as if you were striking a match. This is the correct strike-up method.
- To interrupt welding, lift the electrode quickly away from the piece.
Connecting the electrode-holder clamp welding cable
On the end take a special terminal that is used to close the uncovered part of the
7. MAINTENANCE
electrode.
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This cable is connected to the terminal with the symbol (+)
WARNING! BEFORE CARRYING OUT MAINTENANCE OPERATIONS MAKE
Connecting the welding current return cable
SURE THE WELDING MACHINE IS SWITCHED OFF AND DISCONNECTED FROM
This is connected to the piece being welded or to the metal bench supporting it, as close
THE MAIN POWER SUPPLY.
as possible to the join being made.
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This cable is connected to the terminal with the symbol (-)
7.1 ROUTINE MAINTENANCE
5.5.2 TIG welding with scratch strike
ROUTINE MAINTENANCE OPERATIONS CAN BE CARRIED OUT BY THE
- TIG Torch: the current-carrying cable should be connected to the negative terminal
OPERATOR.
(-).
- Earth return cable: this should be connected to the positive terminal (+); the earth
7.1.1 Torch
clamp at the other end should be connected to the piece to be welded or to a metal
- Do not put the torch or its cable on hot pieces; this would cause the insulating
bench, as close as possible to the joint being made.
materials to melt, making the torch unusable after a very short time.
- Connection to the protective gas bottle for TIG welding. Screw the pressure
- Make regular checks on the gas pipe and connector seals.
reduction valve on to the bottle valve. Please note that the protective gas flow rate
- Accurately match collet and collet body with the selected electrode diameter in order
(litres/minute) can only be regulated using the pressure control valve on the bottle.
to avoid overheating, bad gas diffusion and poor performance.
Prepare the flexible pipe for feeding the protective gas to the torch. Open the manual
- At least once a day check the terminal parts of the torch for wear and make sure they
valve on the torch before welding and close it at the end of welding.
are assembled correctly: nozzle, electrode, electrode-holder clamp, gas diffuser.
WARNING! Always close the gas bottle valve at the end of the job.
- Before using the welding machine, always check the terminal parts of the torch for
wear and make sure they are assembled correctly: nozzle, electrode, electrode-
Warnings:
holder clamp, gas diffuser.
- Turn the welding cable connectors right down into the quick connections (if present),
to ensure a perfect electrical contact; otherwise the connectors themselves will
overheat, resulting in their rapid deterioration and loss of efficiency.
7.2 EXTRAORDINARY MAINTENANCE
- The welding cables should be as short as possible.
EXTRAORDINARY MAINTENANCE OPERATIONS SHOULD BE CARRIED OUT
- Do not use metal structures which are not part of the workpiece to substitute the
ONLY AND EXCLUSIVELY BY SKILLED OR AUTHORISED ELECTRICAL-
return cable of the welding current: this could jeopardise safety and result in poor
MECHANICAL TECHNICIANS.
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welding.
WARNING! BEFORE REMOVING THE WELDING MACHINE PANELS AND
WORKING INSIDE THE MACHINE MAKE SURE THE WELDING MACHINE IS
6. WELDING: DESCRIPTION OF THE PROCEDURE
SWITCHED OFF AND DISCONNECTED FROM THE MAIN POWER SUPPLY
6.1 MMA WELDING
OUTLET.
- It is most important that the user refers to the maker's instructions indicated on the
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stick electrode packaging. This will indicate the correct polarity of the stick
If checks are made inside the welding machine while it is live, this may cause
electrode and the most suitable current.
serious electric shock due to direct contact with live parts and/or injury due to
- The welding current must be regulated according to the diameter of the electrode in
direct contact with moving parts.
use and the type of the joint to be carried out: see below the currents corresponding
- Inspect the welding machine regularly, with a frequency depending on use and the
to various electrode diameters:
dustiness of the environment, and remove the dust deposited on the transformer,
ø Electrode (mm) Welding current (A)
reactance and rectifier using a jet of dry compressed air (max. 10bar).
min. max.
- Do not direct the jet of compressed air on the electronic boards; these can be cleaned
1,6 25 - 50
with a very soft brush or suitable solvents.
2 40 - 80
- At the same time make sure the electrical connections are tight and check the wiring
2,5 60 - 110
for damage to the insulation.
3,2 80 - 160
- At the end of these operations re-assemble the panels of the welding machine and
4 120 - 200
screw the fastening screws right down.
- The user must consider that, according to the electrode diameter, higher current
- Never, ever carry out welding operations while the welding machine is open.
values must be used for flat welding, whereas for vertical or overhead welds lower
current values are necessary.
- As well as being determined by the chosen current intensity, the mechanical
8. TROUBLESHOOTING
characteristics of the welded join are also determined by the other welding
IN CASE OF UNSATISFACTORY FUNCTIONING, BEFORE SERVICING MACHINE
parameters i.e. arc length, working rate and position, electrode diameter and quality
OR REQUESTING ASSISTANCE, CARRY OUT THE FOLLOWING CHECK:
(to store the electrodes correctly, keep them in a dry place protected by their
- Check that the welding current, which is regulated by the potentiometer with a
packaging or containers).
graduated amp scale, is correct for the diamter and electrode type in use.
- The properties of the weld also depend on the ARC-FORCE value (dynamic
- Check that when general switch is ON the relative lamp is ON. If this is not the case
behaviour) of the machine. The selector switch on the panel can be used to select this
then the problem is located on the mains (cables, plugs, outlets, fuses, etc.)
parameter. If the selector is switched to the "TIG with scratch strike" position, the
- Check that the yellow led (ie. thermal protection interruption- either over or
ARC-FORCE and HOT START functions are completely eliminated.
undervoltage or short circuit) is not lit.
It should be noted that high ARC-FORCE values achieve better penetration and allow
- Check that the nominal intermittance ratio is correct. In case there is a thermal
welding in any position typically with basic and cellulose electrodes.
protection interruption, wait for the machine to cool down, check that the fan is
- It is possible that welding with particular rutile electrodes creates excessive spray: in
working properly.
this case we recommend turning the selector on the front of the welding machine to
- Check the mains voltage: if the value is too high or too low the welding machine will
the TIG position.
be stopped.
- Check that there is no short-circuit at the output of the machine: if this is the case
6.1 1 Procedure
eliminate the incovenience.
- Holding the mask IN FRONT OF THE FACE, strike the electrode tip on the workpiece
- Check that all connections of the welding circuit are correct, particularly that the
as if you were striking a match. This is the correct strike-up method.
work clamp is well attached to the workpiece, with no interferring material or
WARNING: do not hit the electrode on the workpiece, this could damage the
surface-coverings (ie. Paint).
electrode and make strike-up difficult.
- Protective gas must be of appropriate type (Argon 99,5%) and quantity.
- As soon as arc is ignited, try to maintain a distance from the workpiece equal to the
diameter of the electrode in use. Keep this distance as much constant as possible for
the duration of the weld. Remember that the angle of the electrode as it advances
should be of 20-30 grades (FIG. H).
- At the end of the weld bead, bring the end of the electrode backward, in order to fill the
weld crater, quickly lift the electrode from the weld pool to extinguish the arc.
CHARACTERISTICS OF THE WELD BEAD (FIG. HI)
6.2 TIG WELDING WITH SCRATCH STRIKE
TIG welding is a welding procedure that exploits the heat produced by the electric arc
that is struck, and maintained, between a non-consumable electrode (tungsten) and the
piece to be welded. The tungsten electrode is supported by a torch suitable for
transmitting the welding current to it and protecting the electrode itself and the weld pool
from atmospheric oxidation, by the flow of an inert gas (usually argon: Ar 99%) which
flows out of the ceramic nozzle.
To achieve a good weld the pieces should be carefully cleaned and free of oxidation, oil,
grease, solvents etc.
It is necessary to sharpen the tungsten electrode axially on a grinding wheel, as shown
in FIG. L making sure that the tip is perfectly centred to prevent arc deviation. It is
important to carry out the grinding along the length of the electrode. This operation
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