CEA CONVEX 4000 vision Operator's Manual page 15

2) Start the welding machine by selecting position 1 on the
line switch (Pos. 3, Fig. A).
3) Make the adjustments and do the parameter settings on
the VS control panel (read the enclosed manual carefully).
4) Carry out welding by moving the torch to the workpiece.
Strike the arc (press the electrode quickly against the met-
al and then lift it) to melt the electrode, the coating of which
forms a protective residue. Then continue welding at an in-
clination of about 60° compared with the metal in relation
to the direction of welding.
PART TO BE WELDED
The part to be welded must always be connected to ground
in order 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 damage to other electric equipment. When it is nec-
essary to connect the part to be welded to ground, you should
make a direct connection between the part and the ground
shaft. In those countries in which such a connection is not al-
lowed, 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
values of current to use are shown in the table with the respec-
tive 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 electrode manufacturer.
The current to be used depends on the welding positions and
the type of joint, and it increases according to the thickness and
dimensions of the part.
The current intensity to be used for the different types of weld-
ing, 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 fol-
lowing formula:
I = 50 × (Øe - 1)
Where:
I = intensity of the welding current
Øe = electrode diameter
Example:
For electrode diameter 4 mm
I = 50 × (4 - 1) = 50 × 3 = 150A
TIG welding with "Lift"
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 pos-
sible to reduce tungsten inclusions on ignition to a minimum.
The molten bath and the electrode are protected by and inert
gas (for example, 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. 4, Fig. A).
Welding Ø electrode
thickness (mm) (mm)
1,2 ÷ 2 1,6
1,5 ÷ 3 2
3 ÷ 5 2,5
5 ÷ 12 3,25
≥ 12 4
≥ 20 ≥ 5
Ø ELECTRODE
(mm)
1
1,6
2,4
3,2
4
FIG. D
FIG. E
3) Make the adjustments and do the parameter settings on
the VS 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
movement 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 switch-
ing off the arc will introduce a slope down and it will switch
off automatically.
15
Table 3
Ø electrode
(mm)
1,6
2
2,5
3,25
4
5
6
ELECTRODE TYPE
Current adjustment field (A)
TIG DC
Tungsten Tungsten
Ce 1% Rare ground 2%
Grey Turchoise
10-50 10-50
50-80 50-80
80-150 80-150
150-250 150-250
200-400 200-400
Table 4
Current (A)
30 ÷ 60
40 ÷ 75
60 ÷ 110
95 ÷ 140
140 ÷ 190
190 ÷ 240
220 ÷ 330
Table 5