Spot Welding - Telwin PCP 18 Mode D'emploi

welder correspond to the mains voltage and frequency available at the place of
installation.
The spot-welder should only and exclusively be connected to a power supply system
with the neutral conductor connected to earth.
5.4.2 Connecting the power supply cable to the spot-welder (FIG.F)
Remove the right side panel, assemble the supplied cable clip at the hole drilled on the
back panel.
Pass the power supply cable through the cable clip and connect it to the power supply
block (phases L1(N) L2) and to the screw terminal of the yellow-green earth protection
conductor.
Depending on the terminal block model, fit the cable terminals as shown in the diagram
(FIG.F1, F2).
Block the cable by tightening the screws on the cable guide.
See the "TECHNICAL DATA" paragraph for the minimum allowed section of the
conductors.
5.4.3 Plug and socket
Connect the power supply cable to a standardised plug (3P+T : only two pins are used:
INTERPHASE CONNECTION!) of adequate capacity and prepare a power outlet
protected by fuses or by an automatic circuit-breaker; the appropriate earth terminal
should be connected to the earth conductor (yellow-green) of the power line.
The capacity and specifications of the fuses and circuit-breaker are given in the
paragraph on "TECHNICAL DATA".
Should several spot welders be installed, distribute the power cyclically among the three
phases in order to obtain a more balanced load; e.g.:
spot-welder 1: power supply L1-L2;
spot-welder 2: power supply L2-L3;
spot-welder 3: power supply L3-L1.
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WARNING! Failure to observe the rules given above will invalidate the (class
I) safety system provided by the manufacturer causing serious risks to people
(e.g. electric shock) and objects (e.g. fire).
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5.5 PNEUMATIC CONNECTION (FIG. G )
(PCP models only)
- Set up a compressed air line with working pressure of at least 6 bar.
- Screw the pressure GAUGE (supplied with the spot-welder) into the special threaded
hole located on the pressure reducing valve.
- Connect a flexible pipe for compressed air (internal diameter 8-9) through the special
opening located on the rear of the machine to the lubricator-reducer-filter group
connector located on the left side; seal off with suitable hose clamps. Pour ISO FD22
oil into the lubricator cup through the special cap (screw).
5.6 CONNECTING THE COOLING CIRCUIT (FIG.H)
It is necessary to set up a water delivery pipe for maximum temperature 30 °C, with
minimum flow rate not less than that specified in TECHNICAL DATA. It is possible to set
up an open cooling circuit (discarding the return water) or a closed circuit as long as the
temperature and water flow rate parameters are respected.
Remove the left side panel in order to reach the flexible delivery and return water pipes
and then pass them through the special openings located on the rear panel. Connect the
delivery pipe (marked by a label) to the external water supply, ensuring correct
discharge and flow rate in the return pipe.
WARNING! Welding operations performed without or with insufficient water flow could
cause the spot-welder to break down due to overheating.

6. SPOT WELDING

6.1 PRELIMINARY OPERATIONS
Before carrying out any spot-welding operation it is necessary to make a series of
checks and adjustments, which should be carried out with the general switch in the "O"
position (with the padlock closed in PCP versions) and with the compressed air supply
switched off (DISCONNECTED).
- Ensure that the electric connection is done according to the previous instructions.
- Put the cooling water into circulation.
- Adjust diameter "d" of the electrode contact surface according to the thickness "s" of
the sheet to be spot welded, according to relationship
- Between the electrodes slide a shim equivalent to the thickness of the sheet to be
spot welded; ensure that the arms, brought together manually, are parallel and that
the electrode holders are centred.
If necessary, make some adjustments by loosening the electrode holder locking
screws until you find the most suitable position for the job to be performed; secure the
locking screws tightly.
In models PTE and PCP28, the gap between the arms can also be regulated by
adjusting the fastening screws of the lower armholder casting (see technical data).
- Open the safety gate located on the rear of the spot-welder by loosening the four
fastening screws to get at the electrode force adjustment nut (wrench No.30).
Compressing the spring (screw the nut clockwise) will cause the electrodes to exert
gradually increasing force with values between the minimum and the maximum (see
technical data).
Such force will increase in proportion to the increase in the thickness of the sheets to
be welded and to the diameter of the electrode tip.
- Close the gate to prevent extraneous matter from entering and to prevent accidental
contact with live or moving parts.
- Check the compressed air connection in PCP models, connect the feed pipe to the
pneumatic system, adjust the pressure by turning the reducer knob until the gauge
reads 6 bar (90 PSI).
6.2 ADJUSTING THE PARAMETERS
The parameters determining the diameter (section) and the mechanical resistance of
spot welding are:
- force exerted by the electrodes (daN); 1 daN = 1.02 Kg.
- diameter of the electrode contact surface (mm);
- welding current (kA);
- welding time (cycles): at 50Hz 1 cycle = 0.02 sec.
In summary, all the above factors must be taken into consideration in adjusting the spot-
welder given that they interact between each other with relatively ample margins.
Furthermore, other factors that could modify the results should not be neglected. These
are:
d = 4 ÷ 6 · Ö s.
- 7 -
- excessive voltage drops on the power line;
- spot-welder overheating due to insufficient cooling or non-observance of the duty
cycle;
- shape and size of workpiece between the arms;
- gap between the arms (adjustable in PTE - PCP 28 models);
- length of arms (see technical data).
Failing precise knowledge, you should run some spot welding tests using sheets having
the same quality and thickness as the job to be performed.
Whenever possible, use high currents (adjust using the "POWER" potentiometer from
20% to 100% of spot-welder capacity) and short periods (adjust using the "CYCLES"
potentiometer from 1 to 100).
6.3 PROCEDURE
- Close the general switch (position "I"); the green LED lights up; power OK, spot-
welder ready.
- PCP MODEL: press "start-up"
to welding position.
- Place the sheets to be welded on the lower electrode.
- Press on the pedal at end-of-stroke (PTE models) or on the pedal valve (PCP
models) to achieve:
A) closing of the sheets between the electrodes with the preset force,
B) passage of the welding current for a preset period (time) and at a preset
intensity, indicated by the green LED
- Shortly (0.5-2 sec.) after the green LED switches off (end of welding operation)
release the pedal. This delay (holding) improves the mechanical characteristics of
the spot weld.
The spot welding operation is deemed correct when, after having run a tensile
strength test, the spot welding core comes out from one of the two sheets.
7. MAINTENANCE
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WARNING! BEFORE CARRYING OUT ANY MAINTENANCE OPERATION
MAKE SURE THE SPOT-WELDER HAS BEEN SWITCHED OFF AND
DISCONNECTED FROM THE MAIN POWER SUPPLY.
In the versions driven by pneumatic cylinder (PCP models) it is necessary to lock
the main switch in the "O" position with the supplied padlock.
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7.1 ROUTINE MAINTENANCE
ROUTINE MAINTENANCE CAN BE CARRIED OUT BY THE OPERATOR
- adjustment/reset of electrode tip diameter and profile;
- electrode alignment checks;
- electrode and arm cooling checks (NOT INSIDE THE SPOT-WELDER);
- checking the spring load (electrode force);
- drain the condensate collected inside the filter cup and tap up the oil level (ISO FD22)
in the compressed air entrance lubricator (PCP models).
7.2 EXTRAORDINARY MAINTENANCE
EXTRAORDINARY MAINTENANCE OPERATIONS SHOULD BE CARRIED OUT
ONLY AND EXCLUSIVELY BY SKILLED, AUTHORISED ELECTRICAL-
MECHANICAL TECHNICIANS.
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WARNING! BEFORE REMOVING THE SPOT-WELDER PANELS AND WORKING
INSIDE THE SPOT-WELDER MAKE SURE THE MACHINE IS SWITCHED OFF AND
DISCONNECTED FROM THE MAIN POWER SUPPLY OUTLET.
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If checks are made inside the spot-welder while it is live, this may cause serious
electric shock due to direct contact with live parts and/or injury due to direct
contact with moving parts.
Depending on how often the spot-welder is run and on the environment conditions,
make regular checks inside the machine and remove the dust and the metallic
particles deposited on the transformer, the thyristor module, the terminal box, etc., by
means of dry compressed air (5 bar maximum).
Do not direct the compressed air jet on the electronic boards: clean them using a
very soft brush or with appropriate solvents.
- ensure that the wiring insulation is not damaged and the connections are tight and
free of oxidation.
- ensure that the transformer secondary connection screws to the arm holder castings
are tightly secured and that there are no signs of oxidation or overheating; make the
same checks on the arm-locking and electrode holder screws.
- lubricate all joints and pins.
- ensure correct cooling water flow (minimum flow required) and perfect pipe seals.
- check for any air leakages (PCP models).
- if necessary reduce the approach speed of the electrodes, regulate the throttling at the
pneumatic cylinder release by adjusting the appropriate screws on the cylinder heads.
IF THE SPOT-WELDER DOES NOT RUN PROPERLY AND BEFORE PERFORMING A
THOROUGH MACHINE CHECK OR GETTING IN TOUCH WITH THE AFTER SALES
SERVICE CENTER, CHECK WHETHER:
- with the spot-welder general switch closed (position "I"), the green LED
this is not the case, check for failures in the power supply line (cables, outlets, plugs,
fuses, excessive drop in voltage, etc.)
&
- the yellow LED is on (thermal safeguard); wait until the LED goes off before re-
starting the spot-welder (PCP models, push-button
water flow and, if necessary, reduce duty cycle.
- with the pedal or the cylinder activated, the electric control actuator has indeed closed
the terminals (contacts) giving the OK to the electronic board: green LED
the preset time.
- the elements making up the secondary circuit (arm holder castings - arms - electrode
holders) are inefficient due to loose screws or oxidation.
- welding parameters (electrode force and diameter, time and welding current) are
suitable for the job to be performed.
In PCP models check also whether:
- the compressed air pressure is lower than the triggering limit of the safeguard device;
- the cycle selector is erroneously in position
(
push-button and turn the cycle selector
%
switching on and off.
(
); ensure correct cooling
#
(pressure only - spot-welder does not
$
*
is on; if
%
on for