Spot Welding - Telwin PCP 28 Manual De Instrucciones

4.3.2 "START" button
This push-button must be pressed to control welding in each of the following conditions:
- every time the main switch has tripped (pos. "O" => pos. "I");
- each time the safety/protection devices cut in;
- when the power supply is reinstated (electricity and compressed air) following a
shutdown of power supplies or a malfunction.
ATTENTION! PERIODICALLY MAKE SURE THE SAFE START
FUNCTION OPERATES CORRECTLY.
4.3.3 NO WELDING / WELDING cycle switch
- NO WELDING: allows use of the spot welding machine without welding. It is
used to move the arms and close the electrodes without current supplies.
RESIDUAL RISK! This operating mode also causes the residual risk
of crushing of the upper limbs: take all necessary precautions (see
safety chapter).
- WELDING (normal welding cycle): allows the spot welding machine to perform
welding operations.
4.3.4 Thermal protection switch (AL1)
This is triggered by overheating of the spot welding machine due to low capacity or
total lack of cooling water, or by a work cycle (DUTY CYCLE) that exceeds the allowed
thermal threshold.
The triggered switch is signalled by the icon in FIG. D2-9 and the AL1 icon switching
on.
EFFECT: current block (welding inhibited).
RESET: manual (using the "START" button) after the machine temperature falls within
the allowed threshold (the AL1 icon will switch off and the "START" icon will switch on).
4.3.5 Compressed air safety switch (AL6 - PCP mod. only)
This is triggered by lack of or low pressure (p < 2.5 ÷ 3bar) of the compressed air
supply; the triggered switch is indicated on the pressure gauge (0 ÷ 3bar) and the AL6
icon on the display.
EFFECT: all movement is blocked, the electrodes open (exhauster cylinder); power is
shut down (welding inhibited).
RESET: manual (using the "START" button) after the machine pressure falls within the
allowed threshold ("START" indication on the display).
4.3.6 Overvoltage and undervoltage trip switch (AL3 and AL4).
This is triggered by an excessive overvoltage or undervoltage of the electricity
supply; the triggered switch is indicated on the display by AL3 (overvoltage) and AL4
(undervoltage).
EFFECT: all movement is blocked, exhauster cylinder (if installed); power is shut down
(welding inhibited).
RESET: manual (using the "START" button) after the machine pressure falls within the
allowed voltage limits ("START" indication on the display).
5. INSTALLATION
WARNING! CARRY OUT ALL INSTALLATION OPERATIONS AND
ELECTRICAL AND PNEUMATIC CONNECTIONS WITH THE SPOT-WELDER
COMPLETELY SWITCHED OFF AND DISCONNECTED FROM THE POWER
SUPPLY OUTLET. THE ELECTRICAL AND PNEUMATIC CONNECTIONS MUST
BE MADE ONLY AND EXCLUSIVELY BY AUTHORISED, SKILLED PERSONNEL.
5.1 PRELIMINARY OPERATIONS
Unpack the spot-welder, assemble the separate parts as indicated below.
5.2 LIFTING THE SPOT-WELDER (FIG. E)
The spot-welder should be lifted with a double cable and hooks, using the eyebolts
fitted for this purpose.
It is absolutely prohibited to sling the spot-welder in a different way from the one we
prescribed (e.g. on arms or electrodes).
5.3 POSITION
The installation area must be sufficiently large and without obstacles, suitable for
ensuring safe access to the control panel and to the work area (electrodes).
Ensure that there are no obstacles near the cooling air inlets and outlets and that no
conductive dusts, corrosive vapour, humidity, etc. can be sucked in.
Position the spot-welder on a plane surface made of homogeneous and compact
material (floor made of concrete or similar physical characteristics).
Fasten the spot-welder to the floor by means of four M10 bolts, using the special
holes on the base; each individual element anchoring the spot-welder to the floor must
guarantee a tensile strength of at least 60 Kg. (60daN).
Maximum load
The maximum load that can be applied to the lower arm (concentrated on the
electrode axis) is 35 Kg. (35daN).
5.4 CONNECTION TO THE MAIN POWER SUPPLY
5.4.1 Warnings
- Before making any electrical connection, check the rating plate data on the spot
welder to make sure they correspond to the voltage and frequency of the available
power supply where the machine is to be installed.
- The spot welder must be connected only and exclusively to a power supply with the
neutral conductor connected to earth.
- To guarantee protection against any direct contact always use the differential
switches indicated below:
- Type A ( ) for single-phase machines;
- Type B ( ) for three-phase machines;
- In order to satisfy the requirements of the EN 61000-3-11 (Flicker) standard we
recommend connecting the spot welder to interface points of the main power
supply that have an impedance of less than Zmax = 0.066 ohm.
- The spot welder does not fall within the requisites of IEC/EN 61000-3-12 standard.
Should it be connected to a public mains system, it is the installer's responsibility
to verify that the spot welding machine itself is suitable for connecting to it (if
necessary, consult the distribution network company).
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 a normalized plug to the power cable (3P+T: only 2 poles are used for the
400V INTERPHASE SYSTEM connection; 2P+T: 230V INTERPHASE connection)
of appropriate capacity and prepare a power supply outlet fitted with fuses or an
automatic circuit-breaker; the corresponding earth terminal should be connected to
the (yellow-green) earth conductor of the power supply.
The capacity and intervention characteristics of the fuses and circuit-breaker switch
are given in the paragraph "OTHER TECHNICAL DATA" and/or in TAB. 1.
Should two or more spot welders be installed, distribute the power supply cyclically
between the three phases in order to create a more balanced load; for example:
spot welder 1: power supply L1-L2;
spot welder 2: power supply L2-L3;
spot welder 3: power supply L3-L1.
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).
5.5 PNEUMATIC CONNECTION (FIG. G) (PCP mod. only)
- Prepare a compressed air supply line with a working pressure of at least 6 bar.
- Connect the gas pipe fitting, supplied as an accessory, to the 1/8 gas coupling in
FIG. G-1; use teflon tape to guarantee airtight sealing.
- Connect a compressed air hose of an adequate size for the fitting used); use a
suitable clip or collar to guarantee airtight sealing.
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.
Connect the water fittings supplied as accessories to the 1/8 gas couplings in FIG. H:
the water couplings are fitted with "OR" sealing rings and do not require the application
of teflon tape.
Connect the water delivery pipe (FIG. H-1) to the external water channelling, checking
for correct outflow and the capacity of the return pipe (FIG. H-2); use a suitable clip or
collar to guarantee airtight sealing.
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 d = 4 ÷ 6 · √s.
- 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.
- Also regulate the flow reducer in FIG. D3-2 to decelerate the descent of the
electrodes;
It is recommended to compensate the deceleration of the arm closure with a longer
approach time to allow the force to reach the maximum level before the machine
starts welding.
Indicatively, with an inlet pressure of 8 bar and the regulator screw unscrewed
half way, set 100 approach cycles (2s); with the regulator screw fully open (screw
completely turned in a counter clockwise direction and the airflow not choked) set
20 cycles (400ms).
- 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:
- excessive voltage drops on the power line;
- spot-welder overheating due to insufficient cooling or non-observance of the duty
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