Telwin SUPERPLASMA 83 HF Mode D'emploi page 6

these instructions.
Failure to comply with these rules may cause serious hazards,
endangering the physical safety of the user and damaging the
apparatus.
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6. PLASMA CUTTING: DESCRIPTION OF THE PROCEDURE
The plasma arc and the application principle in plasma cutting.
Plasma is a gas that is heated to an extremely high temperature and is
ionised so that it becomes an electrical conductor. This cutting procedure
uses the plasma to transfer the electric arc to the metal piece that is
melted by the heat and hence separated. The torch uses compressed air
form a single source, for both the plasma gas and the cooling and
protection gas.
HF strike
This type of strike is normally used on models with currents of over 50A.
Cycle start is determined by a high frequency/high voltage ("HF") arc that
is used to strike a pilot arc between the electrode (-ve polarity) and the
torch nozzle (+ve polarity). When the torch is brought close to the piece to
be cut, which is connected to the (+) polarity of the power source, the pilot
arc is transferred to set up a plasma arc between the electrode (-) and the
piece itself (the cutting arc): The pilot arc and HF strike are disabled as
soon as the plasma arc is established between the electrode and the
piece.
Pilot arc hold time is set in the factory at 2 s; if there is no arc transfer
within this time the cycle is automatically stopped, apart from the
continuance of cooling air.
To re-start the cycle it is necessary to release the torch button and then
press it again.
Shorting strike
This type of strike is normally used on models with currents of less than
50A.
Cycle start is determined by movement of the electrode inside the torch
nozzle, which is used to strike a pilot arc between the electrode (-ve
polarity) and the nozzle itself (+ve polarity).
When the torch is brought close to the piece to be cut, which is connected
to the (+) polarity of the power source, the pilot arc is transferred to set up
a plasma arc between the electrode (-) and the piece itself (the cutting
arc):
The pilot arc is disabled as soon as the plasma arc is established
between the electrode and the piece.
Pilot arc hold time is set in the factory at 2 s; if there is no arc transfer
within this time the cycle is automatically stopped, apart from the
continuance of cooling air.
To re-start the cycle it is necessary to release the torch button and then
press it again.
Preliminary operations.
Before starting cutting operations, make sure the consumable parts have
been fitted correctly by inspecting the head of the torch, as described in
the chapter on "TORCH MAINTENANCE".
- Switch on the power source and set the cutting current (FIG. B, C),
basing it on the thickness and type of the metal that is to be cut. TAB. 3
shows the cutting rate for various thicknesses of aluminium, iron and
steel.
- Press and release the torch button so that there is an outflow of air (
30 seconds of post-air).
³
- During this period, adjust the air pressure until the reading on the
pressure gauge corresponds to the required value in "bar" for the
particular torch being used (TAB. 2).
- Operate the air button so that the air flows out of the torch.
- Adjust the knob: pull upwards to release it and turn it to adjust the
pressure to the value given in the TECHNICAL INFORMATION
ABOUT THE TORCH.
- When the required reading (bar) is shown on the pressure gauge,
press the knob to lock the pressure at the adjusted value.
- Allow the last air to flow out naturally in order to facilitate removal of any
condensation that may have formed inside the torch.
Important:
- Contact cut (with torch nozzle in contact with piece being cut): this can
be applied with a max current of 40-50A (higher current values will
immediately destroy the nozzle-electrode-nozzle holder).
- Space cutting (with a spacer mounted on the torch, FIG. M): this can be
applied for currents of over 35A;
- Extended nozzle and electrode: this can be applied where provided
for.
Cutting operations (FIG. N).
- Bring the torch nozzle close to the edge of the piece (at about 2 mm),
press the torch button; after about 1 second (pre-air) the pilot arc will
strike.
- If the distance is right the pilot arc will immediately transfer to the piece,
causing the cutting arc to strike.
- Move the torch at a constant rate over the surface of the piece along
the ideal cutting line.
- Adjust the cutting rate according to the thickness and the selected
current, making sure that the arc comes out of the lower surface of the
piece at an inclination of 5-10° to the vertical in the opposite direction
to the cutting direction.
- If the torch and piece are too far apart or if there is no material (end of
cut) the arc will immediately be cut off.
- It is always possible to break the (cutting or pilot) arc by releasing the
torch button.
Drilling (FIG. O)
When this operation is necessary, or to start cutting in the centre of the
piece, strike the arc with an inclined torch and bring it gradually to a
vertical position.
- This procedure will stop arc returns or melted particles from damaging
the nozzle hole and causing rapid wear.
- It is possible to drill pieces directly when their thickness is below 25%
of the maximum allowed range.
7. MAINTENANCE
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WARNING! BEFORE
OPERATIONS, MAKE SURE THAT THE PLASMA CUTTING SYSTEM
IS SWITCHED OFF AND DISCONNECTED FROM THE MAIN POWER
SUPPLY.
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ROUTINE MAINTENANCE
ROUTINE MAINTENANCE CAN BE CARRIED OUT BY THE
OPERATOR.
TORCH (FIG. P)
Depending on the amount of use, make regular checks on the wear of the
parts of the torch concerned with the plasma arc and proceed likewise if
cutting defects are noted.
1- Spacer.
Change it if it is so deformed or covered with slag that it is impossible to
maintain the correct position of the torch (distance and
perpendicularity).
2- Nozzle holder.
Unscrew it manually from the head of the torch. Clean it carefully or
change it if it is damaged (burnt, deformed or cracked). Make sure the
top metal section is intact (torch safety rocker).
3- Nozzle.
Check for wear on the plasma arch passage hole and on the inside and
outside surfaces. If the hole is larger than the original diameter or if it is
deformed, change the nozzle. If the surfaces are particularly oxidized
clean them with very fine abrasive paper.
4- Air distribution ring.
Make sure there are no burns or cracks and that the air passage holes
are not blocked. If damaged, change the ring immediately.
5- Electrode.
Change the electrode when the depth of the crater formed on the
emitter surface is approx. 1.5 mm (FIG. Q, Q1).
6- Torch body, handgrip and cable.
These components do not normally need any particular maintenance
apart from regular inspection and careful cleaning without using any
kind of solvent. If the insulation is damaged, with breakages, cracks or
burns etc., or if the electric leads are loose, the torch may not be used
because it does not satisfy safety requirements.
In this case repairs (extraordinary maintenance) cannot be done on
the spot and the torch must be sent to an authorised service centre,
which will be able to carry out the special tests needed after the repair
has been done.
In order to keep the torch and cable in good working order, take the
following precautions:
- do not allow the torch and cable to come into contact with hot or red-
hot parts.
- do not pull the cable hard.
- do not pass the cable over pointed or sharp edges or over abrasive
surfaces.
- wind the cable into regular loops if it is longer than needed.
- do not pass over the cable with any vehicle and do not stand on it.
Warning.
- Before carrying out any work on the torch leave it to cool for at least the
complete "post air" time
- Except in special cases, we recommend changing the electrode and
nozzle at the same time.
- Assemble the torch components in the correct order (the reverse of the
order for dismantling).
- Make sure that the distributor ring is fitted the right way round.
- When re-assembling the nozzle holder, screw it down manually, forcing
it slightly.
- Never ever fit the nozzle holder before you assemble the electrode,
distributor ring and nozzle.
- Do not keep the pilot arc struck in air for no reason as this will increase
electrode, diffuser and nozzle wear.
- Do not tighten the electrode too much as this could damage the torch.
- Prompt, correct inspection procedures for the consumable parts of the
torch are essential for safe, correct operation of the cutting system.
- If the insulation is damaged, with breakages, cracks or burns etc., or if
the electric leads are loose, the torch may not be used because it does
not satisfy safety requirements. In this case repairs (extraordinary
maintenance) cannot be done on the spot and the torch must be sent to
an authorised service centre, which will be able to carry out the special
tests needed after the repair has been done.
Compressed air filter (FIG. L)
- The filter is designed for automatic condensation drainage whenever it
is disconnected from the compressed air line.
- Inspect the filter regularly; if there is water in the glass it can be drained
off manually by pushing the drain connector upwards.
- If the filter cartridge is especially dirty it must be changed in order to
prevent an excessive pressure loss.
EXTRAORDINARY MAINTENANCE
EXTRAORDINARY MAINTENANCE MUST BE CARRIED OUT ONLY
AND EXCLUSIVELY BY AUTHORISED EXPERT OR SKILLED
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CARRYING OUT MAINTENANCE