Title of Invention

AN ADAPTOR FOR GAS TUNGSTEN ARC WELDING FOR PULSED ALTERNATING DUAL SHIELDING GAS SUPPLY OF ARGON AND HELIUM

Abstract Accordingly there is provided 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. The apparatus comprises at least two hoses carrying two different shielding gases from two individual gas cylinders, the atleast two hoses being connected to respective input terminals provided in a gas supply alternator. A GTAW torch is connected to respective outlets provided in the gas supply alternator via two individual hoses. 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 valve are arranged to alternate frequency range of 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.
Full Text 2 FIELD OF INVENTION
The invention generally relates to an apparatus 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 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.
BACKGROUND OF INVENTION
GTAW is one of the important arc welding processes widely used in the fabrication industries all over 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.

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However, for welding of non-ferrous metals like aluminium and copper, 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 argon gas. Therefore a mixture of argon and helium is often for GTA welding of aluminium 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 ratio 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.
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.

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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.

5 SUMMARY OF INVENTION
Accordingly there is provided 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. The apparatus comprises at least two hoses carrying two different shielding gases from two individual gas cylinders, the atleast two hoses being connected to respective input terminals provided in a gas supply alternator. A GTAW torch is connected to respective outlets provided in the gas supply alternator via two individual hoses. 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 valve are arranged to alternate frequency range of 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.

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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)

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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.

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WE CLAIM
1. 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, the apparatus comprising :
- atleast two hoses (3,4) carrying two different shielding gases from
two individual gas cylinders (1,2), the atleast two hoses (3,4) being
connected to respective input terminals (5,6) provided in a gas
supply alternator (9);
- 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) including a timer circuit (T1, T2) for controlling the duration of flow for each individual gas, and in that at least two solenoid valve (Si, S2) being arranged 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.

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3. The apparatus as claimed in claim 1, wherein the GTAW torch (16)
comprises at least two nipples (14,15).
4. 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, as substantially described herein and illustrated
with reference to the accompanying drawing.

Accordingly there is provided 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. The apparatus comprises at least two hoses carrying two different shielding gases from two individual gas cylinders, the atleast two hoses being connected to respective input terminals provided in a gas supply alternator. A GTAW torch is connected to respective outlets provided in the gas supply alternator via two individual hoses. 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 valve are arranged to alternate frequency range of 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.

Documents:

00280-kol-2007 correspondence-1.1.pdf

00280-kol-2007 form-18.pdf

0280-kol-2007-abstract.pdf

0280-kol-2007-assignment.pdf

0280-kol-2007-claims.pdf

0280-kol-2007-correspondence others.pdf

0280-kol-2007-description (complete).pdf

0280-kol-2007-drawings.pdf

0280-kol-2007-form1.pdf

0280-kol-2007-form2.pdf

0280-kol-2007-form3.pdf

280-KOL-2007-ABSTRACT-1.2.pdf

280-KOL-2007-ABSTRACT.1.1.pdf

280-KOL-2007-ABSTRACT.pdf

280-KOL-2007-AMANDED CLAIMS.pdf

280-KOL-2007-AMANDED PAGES OF SPECIFICATION.pdf

280-KOL-2007-CANCELLED PAGES.pdf

280-KOL-2007-CLAIMS.pdf

280-KOL-2007-CORRESPONDENCE-1.1.pdf

280-KOL-2007-CORRESPONDENCE.1.3.pdf

280-KOL-2007-CORRESPONDENCE.pdf

280-KOL-2007-DESCRIPTION (COMPLETE).1.1.pdf

280-KOL-2007-DESCRIPTION (COMPLETE).pdf

280-KOL-2007-DRAWINGS.pdf

280-KOL-2007-EXAMINATION REPORT.1.3.pdf

280-KOL-2007-FORM 1-1.2.pdf

280-KOL-2007-FORM 1.1.1.pdf

280-KOL-2007-FORM 1.pdf

280-KOL-2007-FORM 18.1.3.pdf

280-KOL-2007-FORM 2-1.2.pdf

280-KOL-2007-FORM 2.1.1.pdf

280-KOL-2007-FORM 2.pdf

280-KOL-2007-FORM 3.1.3.pdf

280-KOL-2007-FORM-27.pdf

280-KOL-2007-GPA.1.3.pdf

280-KOL-2007-GRANTED-ABSTRACT.pdf

280-KOL-2007-GRANTED-CLAIMS.pdf

280-KOL-2007-GRANTED-DESCRIPTION (COMPLETE).pdf

280-KOL-2007-GRANTED-DRAWINGS.pdf

280-KOL-2007-GRANTED-FORM 1.pdf

280-KOL-2007-GRANTED-FORM 2.pdf

280-KOL-2007-GRANTED-LETTER PATENT.pdf

280-KOL-2007-GRANTED-SPECIFICATION.pdf

280-KOL-2007-OTHERS.pdf

280-KOL-2007-REPLY TO EXAMINATION REPORT.1.3.pdf

280-KOL-2007-REPLY TO EXAMINATION REPORT.pdf


Patent Number 248982
Indian Patent Application Number 280/KOL/2007
PG Journal Number 38/2011
Publication Date 23-Sep-2011
Grant Date 19-Sep-2011
Date of Filing 26-Feb-2007
Name of Patentee BHARAT HEAVY ELECTRICALS LIMITED
Applicant Address REGIONAL OFFICE: REGIONAL OPERATIONS DIVISION (ROD) PLOT NO:9/1,DJBLOCK 3RD FLOOR,KARUNAMOYEE, SALT LAKE CITY,KOLKATA-700091 REGISTERED OFFICE: BHEL HOUSE,SIRI FORT NEW DELHI-110049
Inventors:
# Inventor's Name Inventor's Address
1 ARASAN RAJA WELDING RESEARCH INSTITUTE, BHEL, TIRUCHY-620014
2 MARIMUTHU SAMIDURAI WELDING RESEARCH INSTITUTE, BHEL, TIRUCHY-620014
3 KANHAIYALAL ROHIRA WELDING RESEARCH INSTITUTE, BHEL, TIRUCHY-620014
PCT International Classification Number B23K9/167
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA