Tig Welding With "Lift" Type Striking; Maintenance - CEA CONVEX 330 basic Manual De Instrucciones

PART TO BE WELDED
The part to be welded must always be connected to ground in or-
der to reduce electromagnetic emission. Much attention must be
afforded so that the ground connection of the part to be welded
does not increase the risk of accident to the user or the risk of dam-
age to other electric equipment. When it is necessary to connect
the part to be welded to ground, you should make a direct con-
nection between the part and the ground shaft. In those countries
in which such a connection is not allowed, connect the part to be
welded to ground using suitable capacitors, in compliance with the
national regulations.
WELDING PARAMETERS
Table 3 shows some general indications for the choice of elec-
trode, based on the thickness of the parts to be welded. The val-
ues of current to use are shown in the table with the respective
electrodes for the welding of common steels and low-grade alloys.
These data have no absolute value and are indicative data only.
For a precise choice follow the instructions provided by the elec-
trode manufacturer.
The current to be used depends on the welding positions and the
type of joint, and it increases according to the thickness and di-
mensions of the part.
The current intensity to be used for the different types of welding,
within the field of regulation shown in table 4 is:
• High for plane, frontal plane and vertical upwards welding.
• Medium for overhead welding.
• Low for vertical downwards welding and for joining small pre-
heated pieces.
A fairly approximate indication of the average current to use in
the welding of electrodes for ordinary steel is given by the follow-
ing formula:
I = 50 × (Øe - 1)
Where:
I = intensity of the welding current
Øe = electrode diameter
Example:
For electrode diameter 4 mm
Ø ELECTRODE
(mm)
Tungsten
1
1,6
2,4 80-150
3,2 150-250
4 200-400
FIG. E
ELECTRODE TYPE
Current adjustment field (A)
TIG DC
Tungsten
Ce 1% Rare ground 2%
Grey Turchoise
10-50 10-50
50-80 50-80
80-150
150-250
200-400

TIG welding with "Lift" type striking

In the TIG process welding is achieved by melting the two metal
pieces to be joined, with the possible addition of material from the
outside, using an arc ignited by a tungsten electrode. The "Lift"
type ignition used in CONVEX equipments makes it possible to
reduce tungsten inclusions on ignition to a minimum. The molten
bath and the electrode are protected by and inert gas (for exam-
ple, Argon). This type of welding is used to weld thin sheet metal
or when elevated quality is required.
1) Connecting the welding cables (Fig. E):
• Connect one end of the gas hose to the gas connecter on
the TIG torch and the other end to the pressure reducer on
the inert gas cylinder (Argon or similar).
• With the machine switched off:
- Connect the ground cable to the snap-on connector
marked + (positive).
- Connect the relative ground clamp to the workpiece or
to the workpiece support in an area free of rust, paint,
grease, etc..
- Connect the TIG torch power cable to the snap-on con-
nector marked - (negative).
2) Start the welding machine by selecting Pos. 1 on the line
switch (Pos. 3, Fig. A).
3) Make the adjustments and do the parameter settings on the
CX control panel (read the enclosed manual carefully).
4) Open the gas cylinder and regulate the flow by adjusting the
valve on the TIG torch by hand.
5) Ignite the electric arc by contact, using a decisive, quick move-
ment without dragging the tungsten electrode on the piece to
be welded ("Lift" type ignition).
6) The welder has a SWS "Smart Welding Stop" system for the
end of TIG welding. Lifting up the torch without switching off
the arc will introduce a slope down and it will switch off auto-
matically.
7) When you have finished welding remember to shut the valve
on the gas cylinder.
Table 5 shows the currents to use with the respective electrodes for
TIG DC welding. This input is not absolute but is for your guidance
Table 5
only; read the electrode manufacturers' instructions for a specific
choice. The diameter of the electrode to use is directly proportion-
al to the current being used for welding.

Maintenance

ATTENTION: Cut off the power supply to the equipment before ef-
fecting any internal inspection.
CONVEX 330-400-500 basic
IMPORTANT: For fully electronic welding machines, removing the
dust by sucking it into the machine by the fans, is of utmost im-
portance.
In order to achieve correct functioning of the machine, proceed
as described:
• Periodic removal of accumulations of dirt and dust inside the
equipment using compressed air. Do not point the jet of air di-
rectly at the electrical parts as this could damage them.
• Periodical inspection for worn cables or loose connections that
could cause overheating.
TORCH
The torch is subjected to high temperatures and is also stressed
by traction and torsion. We recommend not to twist the wire and
not to use the torch to pull the welder. As a result of the above the
torch will require frequent maintenance such as:
• Cleaning welding splashes from the gas diffuser so that the gas
flows freely.
• Substitution of the contact point when the hole is deformed.
• Cleaning of the wire guide liner using trichloroethylene or spe-
cific solvents.
• Check of the insulation and connections of the power cable; the
connections must be in good electrical and mechanical condition.
6
I = 50 × (4 - 1) = 50 × 3 = 150A