FIELD OF INVENTION
The invention generally relates to Gas Metal Arc Welding [GMAW] process to
achieve improved weld quality and reduced shielding gas consumption. More
particularly, the invention relates to an apparatus adaptable to GMAW process
for alternate supply of shielding gases with optimizing the individual gas flow
rate and gas pulsing frequency to a GMAW torch.
BACKGROUND OF INVENTION
GMAW is one of the important arc welding processes widely used for welding of
aluminum in the fabrication industries. GMAW is an electric arc welding process,
which produces coalescence of metals by heating them with an arc established
between a consumable electrode wire and a weldable job. Shielding of the arc
and the molten weld pool is achieved through an externally supplied shielding
gas, which normally is argon. The GMAW process is also known as Metal Inert
Gas (MIG) welding. The GMAW process with argon+ CO2 as the shielding gas is
used in the fabrication industries for welding of carbon and alloy steels also.
However, for welding of non-ferrous metals like aluminum and copper, the
helium gas is preferred for shielding as it gives better plate fusion and weld
penetration. But the cost of helium is higher as compared to that of argon gas.
Therefore, a premixed gas mixture of argon and helium having a mixing ratio of
40% argon and 60% helium is often used for GMAW welding of aluminum and
copper. Each shielding gas has its own properties, including ionization potential,
and each produces a unique arc characteristics. In GMAW, the arc characteristics
varies according to the mixing ratio of the two shielding gases for example argon
and helium.
In conventional GMAW for welding of non-ferrous metals, it is a standard
practice to use argon as the shielding gas. The purity requirement of the gas
depends on the desired weld quality requirement and application. The use of
argon gas for shielding produces a constant arc dynamics. Further, the arc
pressure and weld pool fluidity remain constant.
Pulsed current GMAW is another technique used to vary the arc pressure and
weld pool dynamics. However this technique produces only one dimensional
impact on the weld pool. In contrast thereto, an alternating supply of shielding
gases causes a multi dimensional impact on the arc dynamics including the weld
pool which results in an improved weld quality both in terms of improved fusion
characteristics and reduced porosity level in an aluminum welding.
OBJECTS OF THE INVENTION :
It is therefore an object of the invention to propose an apparatus adaptable to
GMAW process for alternate supply of shielding gases with optimized gas flow
rate and gas pulsing frequency to the welding torch, which eliminates the
disadvantages of the prior art.
Another object of the invention is to propose an apparatus adaptable to GMAW
process for alternate supply of shielding gases with optimized gas flow rate and
gas pulsing frequency to the welding torch, which improves the weld quality.
A still another object of the invention is to propose an apparatus adaptable to
GMAW process for alternate supply of shielding gases with optimized gas flow
rate and gas pulsing frequency to the welding torch, which is enabled to
generate the applicable process parameters to optimize the individual gas flow
rate including the pulsing frequency.
These and other objects and advantages of the invention will be apparent from
the ensuing description.
At the outset of the description, which follows, it is to be understood that the
ensuing description only illustrates a particular from of this invention. However,
such a particular form is only an exemplary embodiment and the teachings of the
invention are not intended to be taken restrictively.
SUMMARY OF THE INVENTION :
Accordingly there is provided an apparatus adaptable to GMAW process for
alternate supply of shielding gases with optimized gas glow rate and gas pulsing
frequency to a GMAW torch. The apparatus comprises at least two hoses
carrying two different shielding gases from two individual gas supply sources, the
atleast two hoses being connected to respective input terminals provided in a
gas supply alternator. A third hose connects the outlet of the gas supply
alternator and a gas solenoid in the welding system. A fourth hose connects the
outlet of the solenoid and a gas inlet of the GMAW torch. The shielding gas
alternator is provided with at least two timer knobs including a timer circuit for
controlling the duration of flow for each individual gas. At least two solenoid
valves are arranged to alternate frequency range of the gas supply.
The alternating shielding gas supply technology overcomes the limitations of
premixed gas method. The technology of alternating supply of shielding gas has
influence on every aspect of the GMA welding process. The alternate supply of
shielding gas causes a dynamic action on the molten weld pool, which results in
improved weld quality both in terms of fusion characteristics and bead
appearance.
The alternate supply of the shielding gas according to the invention produces a
pulsing effect similar to pulsed GMAW but better than that in arc and weld pool
dynamics.
The alternate shielding gas supply methodology generates multi dimensional
impacts to GMAW weld pool resulting in much improved weld quality.
The gas pulsing frequency is adjustable from 1 to 10 cycles/min. The welding
parameters and the alternate shielding gas supply frequency for improved weld
quality in aluminum are also established.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
Figure 1 (Schematic) - Shows an embodiment of the apparatus according to the
invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
Referring now to the drawing, wherein like reference numerals designate
identical or corresponding features throughout the several views. Figure 1 shows
the schematic of the GMA welding with alternate gas supply apparatus. At least
two hoses (3,4) carrying argon and helium gases from individual supply sources
(1,2) are connected to respective input terminals (5,6) provided in a gas supply
alternator (9). The duration of gas flow for each individual gas is controlled by at
least two timer knobs (7, 8) provided in the front panel of the shielding gas
alternator (9). The duration of flow for each individual gas is controlled by at
least two timer knobs (7,8) provided in the front panel of the shielding gas
alternator (9). One gas outlet (10) provided on the front panel of the shielding
gas alternator (9) is connected to a solenoid nipple (11) provided in a wire
feeder (13) from where the gas is carried through a hose to GMAW torch (14).
An adjustment of the timer knobs (7,8) enable alternating/pulsing the supply
frequency of the shielding gas.
The typical GMAW system has a wire spool (12) feeding the wire via a roller-
cum-feeding means (13) to the torch (14). A standard power source (15)
provides the current.
The welding apparatus of the invention as shown in Figure 1, alternates the
shielding gas supply at different frequencies during welding.
WE CLAIM :
1. An apparatus adaptable to GMAW process for alternate supply of
shielding gases with optimized gas glow rates and gas pulsing
frequency to a GMAW torch the apparatus comprising :
atleast two hoses (3,4) carrying two different shielding gases from
two individual gas supply sources (1,2), the atleast two hoses (3,4)
being connected to respective input terminals (5,6) provided in a
gas supply alternator (9);
- a GMAW torch (14) connected to a wire feeder (13), and a solenoid
nipple (11) supplying the two different shielding gases to the torch
(14);
- at least two timer knobs (7,8) including a timer circuit provided to
the gas supply alternator (9) for controlling the supply duration of
the two gases;
- at least two solenoid valves disposed on the alternator (9) to
alternate frequency range of the gas supply.
2. The apparatus as claimed in claim 1, wherein the shielding gas supply
is alternated at a frequency range of 1 to 10 cycles/minute.
3. The apparatus as claimed in claim 1, wherein the gas supply alternator
(9) is provided with a gas outlet (10).
4. The apparatus as claimed in any of the preceding claims, wherein the
wire feeder (13) is enabled to accommodate a wire-spool (12) having
feeding wire enrolled thereon.
5. The apparatus as claimed in claim 1, comprising a power source (15)
for providing current to the welding system.
6. The apparatus as claimed in claim 1, wherein the GMAW torch (14)
supplied with alternate shielding gases of argon and helium for
aluminum welding.
7. An apparatus adaptable to GMAW process for alternate supply of
shielding gases with optimized gas flow-rate and gas pulsing frequency
to a welding torch as substantially described herein and illustrated with
reference to the accompanying drawing.

The invention relates to an apparatus adaptable to GMAW process for
alternate supply of shielding gases with optimized gas glow rates and gas
pulsing frequency to a GMAW torch the apparatus comprising atleast two
hoses (3,4) carrying two different shielding gases from two individual gas
supply sources (1,2), the atleast two hoses (3,4) being connected to
respective input terminals (5,6) provided in a gas supply alternator (9); a
GMAW torch (14) connected to a wire feeder (13), and a solenoid nipple (11)
supplying the two different shielding gases to the torch (14); at least two
timer knobs (7,8) including a timer circuit provided to the gas supply
alternator (9) for controlling the supply duration of the two gases; at least
two solenoid valves disposed on the alternator (9) to alternate frequency
range of the gas supply.