FIELD OF INVENTION
The invention generally relates to an adaptor and process for alternating the supply of
shielding gas to the arc in Gas Tungsten Arc Welding (GTAW) process to achieve
improved weld quality including reduction in shielding gas consumption. More
particularly, the invention relates to an adaptor adaptable to GTAW process to alternate
supply of shielding gases to the welding torch including optimization of gas pulsing
frequency for improved weld quality.
BACKGROUND OF THE INVENTION
GTAW is one of the important arc welding processes widely used in the fabrication
industries allover the world. GTAW is an electric arc welding process, which produces
coalescence of metals by heating them with an arc established between a non-
consumable tungsten electrode and the work. Shielding of the arc and molten weld pool
is obtained through an externally supplied shielding gas, which normally would be
argon. The GTAW process is also known as Tungsten Inert Gas (TIG) welding. The
GTAW process with argon as shielding gas is used in the fabrication industries for
welding of carbon and alloy steels.
However, for welding of non-ferrous metals like aluminum and copper, helium gas is preferred
for shielding a sit gives better plate fusion and weld penetration. But the cost of helium is
higher a compared to argon gas. Therefore a mixture of argon and helium is often for GTA
welding of aluminum or copper. Each shielding gas has its own properties, including ionization
potential, and produces unique arc characteristics. IN GTAW, the arc characteristics will vary
according to the mixing ration of the two shielding gases for example argon and helium.
In conventional GTAW for welding of ferrous metals, it is standard practice to use argon as the
shielding gas. The purity requirement of the gas depends on the weld quality requirement and
application. The use of argon shielding gas produces a constant arc dynamics. The arc pressure
and weld pool fluidity remain constant.
A prior Japanese patent JP 2003290930 entitled "welding torch for consumable electrode gas
shielded arc welding" which discloses in the welding torch, a filter is attached around the orifice,
with the wire gauze of the filter situated at the tip end of the nozzle. As a result, the shielding
gas provided for the tip body passes through the shielding gas jetting port of the tip body and
that of the orifice and further through the wire gauze of the filter, and is then supplied from the
tip end of the nozzle. Consequently, the shielding gas flowing inside the nozzle is straightened,
uniformized in the sped distribution, and elongated in the length of laminar flow of the shielding
gas to be supplied from the tip end of the nozzle.
This prior document discloses a teaching of an apparatus for supply of a single shielding gas
was used to the welding torch and a method of optimizing the gas usage.
A second Japanese prior patent JP 58125377 entitled "gas shielded welding torch" which
describes the shielding gases supplied into a gas cup are accumulated to a high pressure in a
gas chamber, and are ejected at a high velocity to materials to be welded from an annular
nozzle and/or nozzles. In this case, the shielding gases are ejected as cylindrical laminar flow
accurately at a high velocity to around the preceding end of a welding wire unlike in the prior
art; therefore, the biased flow of the shielding gases or the inclusion of air is obviated. When
the shielding gases are ejected as laminar flow from the nozzle and the nozzles, double shields
are provided, by which weld beads are shielded thoroughly. Since the shielding gases are
ejected at a high velocity, sticking of spatters on the gas cup etc. in the stage of welding is
prevented.
This prior patent discloses a teaching of welding torch shielding gas, gas chamber has been
disclosed for single gas.
The known pulsed GTAW technique produces one-dimensional impact on the weld pool.
Whereas the pulsed 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.
OBJECTS OF INVENTION
It is therefore an object of the invention to propose an apparatus adaptable to GTAW process
to alternate supply of shielding gases to the welding torch including optimization of gas pulsing
frequency for improved weld quality.
Another object of the invention is to propose an apparatus adaptable to GTAW
process to alternate supply of shielding gases to the welding torch including
optimization of gas pulsing frequency for improved weld quality, which ensures
delivery of the shielding gas directly to the GTAW torch to avoid mixing of the
gas before entering the torch.
A further object of the invention is to propose an apparatus adaptable to GTAW
process to alternate supply of shielding gases to the welding torch including
optimization of gas pulsing frequency for improved weld quality, which ensures
improved weld quality.
A still further object of the invention is to propose an apparatus adaptable to
GTAW process to alternate supply of shielding gases to the welding torch
including optimization of gas pulsing frequency for improved weld quality, which
is capable of generating suitable process parameters and gas pulsing frequency
for improved weld quality.
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 form 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 INVENTION
The present invention is provided with an adaptor for GTAW for pulsed alternating dual
shielding gas supply of argon and helium and optimization of gas pulsing frequency for
improved weld quality comprising at least two hoses carrying two different shielding
gases from two individual gas cylinders the at least two hoses being connected to
respective input terminals provided in a gas supply alternator and a GTAW torch
connected to respective outlets provided in the gas supply alternator via two individual
hoses characterized in that the shielding gas alternator is provided with at least two
timer knobs, a timer circuit for controlling the duration of flow for each individual gas,
and in that at least two solenoid valve being disposed to alternate frequency range of 1
to 10 cycles/minute of the gas supply.
The pulses alternating shielding gas supply technology overcomes the limitations of
mixed gas method. The technology of pulsed alternating supply of shielding gas has
influence on every aspect of the GTA welding process. The pulsed 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 shielding gas according to the invention produces a pulsing
effect somewhat similar to pulsed GTAW but better than that in dynamics.
The alternate shielding gas supply methodology generates multiple impacts to
GTAW weld pool resulting in much improved weld quality.
The pulsing frequency is adjustable from 1 to 10 cycles/min. The welding
parameters and the alternate shielding gas supply frequency for improved weld
quality is also established.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 (Schematic) - shows an embodiment of the apparatus according to the
invention.
Figure 2 - shows a line diagram of the shielding gas alternator.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF
INVENTION
Referring now to the drawings. Wherein like reference numerals designate
identical or corresponding parts throughout the several views. Fig. 1 shows the
schematic of the alternate gas supply apparatus. At least two hoses (3,4)
carrying argon and helium gases from individual gas cylinders (1,2) are
connected to respective input terminals (5,6) provided in a gas supply 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).
Two gas outlets (10,11) provided on the front panel of the shielding gas
alternator (9) are connected to at least two nipples (14,15) provided in GTAW
torch body (16) directly through two individual hoses (12,13) for each gas. The
length of the hose (13) between the shielding gas alternator (9) and the torch
(16) is kept to the minimum to make it dynamically more responsive. Adjusting
the timer control (7,8) varies the shielding gas alternating/pulsing frequency.
The typical GTAW system has a wire-spool (19) feeding the wire via a roller-cum-
feeding means (18) to the torch (16). A standard power source (17) is provid
current.
The welding apparatus of the invention as shown in Fig. 1, alternates the
shielding gas supply at different frequencies.
As shown in Fig. - 2, SI and S2 are the solenoid valves and Tl and T2 are the
timers used for controlling the flow duration.
WE CLAIM
1. An adaptor for GTAW for pulsed alternating dual shielding gas supply of argon
and helium and optimization of gas pulsing frequency for improved weld quality
comprising:
- at least two hoses (3,4) carrying two different shielding gases from two
individual gas cylinders (1,2) the at least two hoses (3,4) being connected to
respective input terminals (5, 6) provided in a gas supply alternator;
- a GTAW torch (16) connected to respective outlets (10, 11) provided in the gas
supply alternator (9) via two individual hoses (12,13);
characterized in that the shielding gas alternator (9) is provided with at least two
timer knobs (7, 8), a timer circuit (T1, T2) for controlling the duration of flow for
each individual gas, and in that at least two solenoid valve (S1, S2) being
disposed to alternate frequency range of 1 to 10 cycles/minute of the gas supply.
2. The adaptor as claimed in claim 1, wherein the GTAW torch (16) comprises at
least two nipples (14,15).
3. An adaptor adaptable to GTAW process to alternate supply of shielding gases to
the welding torch including optimization of gas pulsing frequency for improved
weld quality, as substantially described herein and illustrated with reference to
the accompanying drawing.

The present invention relates to an adaptor for GTAW for pulsed alternating dual
shielding gas supply of argon and helium and optimization of gas pulsing frequency for
improved weld quality comprising at least two hoses (3,4) carrying two different
shielding gases from two individual gas cylinders (1,2) the at least two hoses (3,4)
being connected to respective input terminals (5, 6) provided in a gas supply alternator
and a GTAW torch (16) connected to respective outlets (10, 11) provided in the gas
supply alternator (9) via two individual hoses (12,13) characterized in that the shielding
gas alternator (9) is provided with at least two timer knobs (7, 8), a timer circuit (T1,
T2) for controlling the duration of flow for each individual gas, and in that at least two
solenoid valve (S1, S2) being disposed to alternate frequency range of 1 to 10
cycles/minute of the gas supply.