Title of Invention	A METHOD AND APPARATUS FOR TANDEM SUBMERGED ARC WELDING USING ONE WIRE FEEDER
Abstract	This invention relates to an improved apparatus for performing tandem submerged arc welding, comprising; a single wire feeder (2) capable of simultaneously feeding two wires; at least two spools (1a, 1b) feeding the wires into two torches (3A, 3B), the spools (1a, 1b) being driven by a wire-feed motor (2); a control box (9) controlling the wire - feed motor (2); at least two power sources (10,11) respectively providing via the first terminals to the first and second torches (3A, 3B); a job (12) connectable to the second terminals of the power sources (10, 11); the wires fed to the two torches (3A, 3B) coming-out of each contact tip (4) to create an arc (5) under flux blanket (6) to form a single weld pool (7).

Title of Invention

A METHOD AND APPARATUS FOR TANDEM SUBMERGED ARC WELDING USING ONE WIRE FEEDER

Abstract

This invention relates to an improved apparatus for performing tandem submerged arc welding, comprising; a single wire feeder (2) capable of simultaneously feeding two wires; at least two spools (1a, 1b) feeding the wires into two torches (3A, 3B), the spools (1a, 1b) being driven by a wire-feed motor (2); a control box (9) controlling the wire - feed motor (2); at least two power sources (10,11) respectively providing via the first terminals to the first and second torches (3A, 3B); a job (12) connectable to the second terminals of the power sources (10, 11); the wires fed to the two torches (3A, 3B) coming-out of each contact tip (4) to create an arc (5) under flux blanket (6) to form a single weld pool (7).

Full Text	2 FIELD OF INVENTION This invention relates to an improved apparatus with a single wire feeder for Tandem Submerged arc welding of steel plates. BACKGROUND OF THE INVENTION In submerged arc welding (SAW), the arc is hidden by a blanket of granular flux. Normally a single wire is used as filler material. It is also possible to use two or more wires to increase productivity. When two wires are used (Tandem Submerged Arc Welding), one wire is connected to a DC power supply and the other wire is connected to AC power supply. Alternatively, both wires are connected to AC power source. Hence, there will be two power supplies, two wire feeders and two torches employed in tandem Submerged arc welding process. In this case two wire feeders independently controlled through separate controls have to be employed. Conventional tandem submerged arc welding requires welding current (wire feed speed) and arc voltage to be pre-set independently to achieve the desired bead geometry. However, the prior art systems are not capable to operate with one feeder and associated controls with a synchronized single point control for the wire feeders. Thus, automatic selection of welding current from the second power source is not feasible in the prior art system. US patent US patent US 7166818 discloses a Process development for making Tandem submerged arc welding. 3 According to the cited invention, an electric arc welding apparatus comprising at least a first consumable electrode and a second consumable electrode movable in unison along a welding path between the edges of two adjacent, mutually grounded plates, a first power supply for passing a first welding current at a first low frequency between the first electrode and the two plates, a second power supply for passing a second welding current at a second low frequency between the second electrode and the two plates, where each of the power supplies includes a three phase voltage input operated at line frequency, a rectifier to convert the input voltage to a DC voltage link and a high frequency switching type inverter converting the DC voltage link to a high frequency AC current, an output rectifier circuit to provide a positive voltage terminal and a negative voltage terminal, and an output switching network operated at a given low frequency for directing a pulsating welding current at the given low frequency from the two terminals across one of the electrodes and the plates, and a circuit for independently adjusting the given low frequency so the value of the first low frequency of the first power supply is different from the second low frequency of the second power supply. Further, US patent US 7220940 discloses a Process development for system for welding with multiple arcs. This invention describes a system for welding with a first and second arc between a first and second electrode respectively and a common work piece , when each of the electrodes is driven by a power lead from a single power 4 source. The system comprises an inductor with a core, a center tap, a first end, a second end, a first coil section between the tap and the first end and a second coil section between the tap and the second end where the power lead is connected to the tap. A first circuit connecting the first arc in series with the first coil section and a second circuit connecting the second arc in series with the second coil section, a first separate auxiliary inductor in the first circuit between the first coil section and the first arc and a second separate auxiliary inductor in the second circuit between the second coil section and the second arc. OBJECTS OF INVENTION An object of the present invention is to propose an improved apparatus with a single wire feeder, for tandem submerged arc welding of steel plates, which can drive two separate filler wires at the same speed. Another object of this invention is to propose an improved apparatus with a single wire feeder, for tandem submerged arc welding of steel plates, which enables reduction in the number of parameters required to be set. Yet another object of the invention is to propose an improved apparatus with a single wire feeder, for tandem submerged arc welding of steel plates, which both power sources is capable of delivering same level of current. A still another object of the invention is to propose an improved apparatus with a single wire feeder, for tandem submerged arc welding of steel plates, which can achieve the same filler metal deposition rate from both wires. 5 These and other objects of the invention are accomplished in accordance with the principles of the invention. Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Figure 1 - shows the Tandem submerged arc welding set up with one wire feeder according to the invention. SUMMARY OF INVENTION Accordingly, there is provided an improved apparatus for performing tandem submerged arc welding, comprising a single wire feeder capable simultaneously feeding two wires; at least two spools feeding the wires into two torches, the spools being driven by a wire-feed motor; a control box controlling the wire - feed motor; at least two power sources respectively providing via the first terminals to the first and second torches; a job connectable to the second terminals of the power sources; the wires fed to the two torches coming-out of each contact tip to create an arc under flux blanket to form a single weld pool. DETAIL DESCRIPTION OF THE INVENTION As shown in figure - 1, the apparatus consists of one wire feeder, which feeds two wires required for tandem submerged arc welding simultaneously. Wires 6 from two spools (la, lb) are fed by the wire feed motor (2) in to the torches 3A and 3B. The wires come out of contact tips (4) to create an arc (5) under flux blanket (6) to form single weld pool (7). The wire feeder (2) is driven by a motor (8) which is controlled by a control box (9). with the power drawn from power source (10). One of the torches 3A is connected to a Direct Current power source (10), while the other torch, 3B is connected to an AC power source, (11). Alternately, both the welding power sources can be AC type. The other terminal of the power source is connected to the job (12). The torches are isolated from each other electrically. 7 WE CLAIM 1, An improved apparatus for performing tandem submerged arc welding, comprising: - a single wire feeder (2) capable of simultaneously feeding two wires; - at least two spools (la, lb) feeding the wires into two torches (3A. 3B), the spools (la, lb) being driven by a wire-feed motor (2); - a control box (9) controlling the wire - feed motor (2); - at least two power sources (10,11) respectively providing via the first terminals to the first and second torches (3A, 3B); - a job (12) connectable to the second terminals of the power sources (10,11); - the wires fed to the two torches (3A, 3B) coming-out of each contact tip (4) to create an arc (5) under flux blanket (6) to form a single weld pool (7). 2. An improved apparatus as claimed in claim 1, wherein one of the power sources (10,11) is D.C, and the other (11) being A.C. power source. 8 3. An improved apparatus as claimed in claim 1 or 2, wherein both the power sources (11,11) is A.C. type. 4. An improved apparatus as claimed in claim 1, wherein both the wires is susceptible to identical deposition rate. 5. An improved apparatus as claimed in any of the preceeding claims, wherein the arc current (5) including the voltages set in the two power sources (10,11) is adjustable to regulate the lead geometry. 6. An improved apparatus for performing tandem submerged arc welding as substantially described and illustrated herein with reference to the accompanying drawings. This invention relates to an improved apparatus for performing tandem submerged arc welding, comprising; a single wire feeder (2) capable of simultaneously feeding two wires; at least two spools (1a, 1b) feeding the wires into two torches (3A, 3B), the spools (1a, 1b) being driven by a wire-feed motor (2); a control box (9) controlling the wire - feed motor (2); at least two power sources (10,11) respectively providing via the first terminals to the first and second torches (3A, 3B); a job (12) connectable to the second terminals of the power sources (10, 11); the wires fed to the two torches (3A, 3B) coming-out of each contact tip (4) to create an arc (5) under flux blanket (6) to form a single weld pool (7).

Full Text

2
FIELD OF INVENTION
This invention relates to an improved apparatus with a single wire feeder for
Tandem Submerged arc welding of steel plates.
BACKGROUND OF THE INVENTION
In submerged arc welding (SAW), the arc is hidden by a blanket of granular flux.
Normally a single wire is used as filler material. It is also possible to use two or
more wires to increase productivity. When two wires are used (Tandem
Submerged Arc Welding), one wire is connected to a DC power supply and the
other wire is connected to AC power supply. Alternatively, both wires are
connected to AC power source. Hence, there will be two power supplies, two
wire feeders and two torches employed in tandem Submerged arc welding
process. In this case two wire feeders independently controlled through separate
controls have to be employed. Conventional tandem submerged arc welding
requires welding current (wire feed speed) and arc voltage to be pre-set
independently to achieve the desired bead geometry. However, the prior art
systems are not capable to operate with one feeder and associated controls with
a synchronized single point control for the wire feeders. Thus, automatic
selection of welding current from the second power source is not feasible in the
prior art system.
US patent US patent US 7166818 discloses a Process development for making
Tandem submerged arc welding.

3
According to the cited invention, an electric arc welding apparatus comprising at
least a first consumable electrode and a second consumable electrode movable
in unison along a welding path between the edges of two adjacent, mutually
grounded plates, a first power supply for passing a first welding current at a first
low frequency between the first electrode and the two plates, a second power
supply for passing a second welding current at a second low frequency between
the second electrode and the two plates, where each of the power supplies
includes a three phase voltage input operated at line frequency, a rectifier to
convert the input voltage to a DC voltage link and a high frequency switching
type inverter converting the DC voltage link to a high frequency AC current, an
output rectifier circuit to provide a positive voltage terminal and a negative
voltage terminal, and an output switching network operated at a given low
frequency for directing a pulsating welding current at the given low frequency
from the two terminals across one of the electrodes and the plates, and a circuit
for independently adjusting the given low frequency so the value of the first low
frequency of the first power supply is different from the second low frequency of
the second power supply.
Further, US patent US 7220940 discloses a Process development for system for
welding with multiple arcs.
This invention describes a system for welding with a first and second arc
between a first and second electrode respectively and a common work piece ,
when each of the electrodes is driven by a power lead from a single power

4
source. The system comprises an inductor with a core, a center tap, a first end, a
second end, a first coil section between the tap and the first end and a second
coil section between the tap and the second end where the power lead is
connected to the tap. A first circuit connecting the first arc in series with the first
coil section and a second circuit connecting the second arc in series with the
second coil section, a first separate auxiliary inductor in the first circuit between
the first coil section and the first arc and a second separate auxiliary inductor in
the second circuit between the second coil section and the second arc.
OBJECTS OF INVENTION
An object of the present invention is to propose an improved apparatus with a
single wire feeder, for tandem submerged arc welding of steel plates, which can
drive two separate filler wires at the same speed.
Another object of this invention is to propose an improved apparatus with a
single wire feeder, for tandem submerged arc welding of steel plates, which
enables reduction in the number of parameters required to be set.
Yet another object of the invention is to propose an improved apparatus with a
single wire feeder, for tandem submerged arc welding of steel plates, which both
power sources is capable of delivering same level of current.
A still another object of the invention is to propose an improved apparatus with a
single wire feeder, for tandem submerged arc welding of steel plates, which can
achieve the same filler metal deposition rate from both wires.

5
These and other objects of the invention are accomplished in accordance with
the principles of the invention. Further features of the invention, its nature and
various advantages will be more apparent from the accompanying drawings and
the following detailed description of the preferred embodiments.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 - shows the Tandem submerged arc welding set up with one wire feeder
according to the invention.
SUMMARY OF INVENTION
Accordingly, there is provided an improved apparatus for performing tandem
submerged arc welding, comprising a single wire feeder capable simultaneously
feeding two wires; at least two spools feeding the wires into two torches, the
spools being driven by a wire-feed motor; a control box controlling the wire -
feed motor; at least two power sources respectively providing via the first
terminals to the first and second torches; a job connectable to the second
terminals of the power sources; the wires fed to the two torches coming-out of
each contact tip to create an arc under flux blanket to form a single weld pool.
DETAIL DESCRIPTION OF THE INVENTION
As shown in figure - 1, the apparatus consists of one wire feeder, which feeds
two wires required for tandem submerged arc welding simultaneously. Wires

6
from two spools (la, lb) are fed by the wire feed motor (2) in to the torches 3A
and 3B. The wires come out of contact tips (4) to create an arc (5) under flux
blanket (6) to form single weld pool (7). The wire feeder (2) is driven by a motor
(8) which is controlled by a control box (9). with the power drawn from power
source (10). One of the torches 3A is connected to a Direct Current power source
(10), while the other torch, 3B is connected to an AC power source, (11).
Alternately, both the welding power sources can be AC type. The other terminal
of the power source is connected to the job (12). The torches are isolated from
each other electrically.

7
WE CLAIM
1, An improved apparatus for performing tandem submerged arc welding,
comprising:
- a single wire feeder (2) capable of simultaneously feeding two
wires;
- at least two spools (la, lb) feeding the wires into two torches (3A.
3B), the spools (la, lb) being driven by a wire-feed motor (2);
- a control box (9) controlling the wire - feed motor (2);
- at least two power sources (10,11) respectively providing via the
first terminals to the first and second torches (3A, 3B);
- a job (12) connectable to the second terminals of the power
sources (10,11);
- the wires fed to the two torches (3A, 3B) coming-out of each
contact tip (4) to create an arc (5) under flux blanket (6) to form a
single weld pool (7).
2. An improved apparatus as claimed in claim 1, wherein one of the power
sources (10,11) is D.C, and the other (11) being A.C. power source.

8
3. An improved apparatus as claimed in claim 1 or 2, wherein both the
power sources (11,11) is A.C. type.
4. An improved apparatus as claimed in claim 1, wherein both the wires is
susceptible to identical deposition rate.
5. An improved apparatus as claimed in any of the preceeding claims,
wherein the arc current (5) including the voltages set in the two power
sources (10,11) is adjustable to regulate the lead geometry.
6. An improved apparatus for performing tandem submerged arc welding
as substantially described and illustrated herein with reference to the
accompanying drawings.

This invention relates to an improved apparatus for performing tandem
submerged arc welding, comprising; a single wire feeder (2) capable of
simultaneously feeding two wires; at least two spools (1a, 1b) feeding the wires
into two torches (3A, 3B), the spools (1a, 1b) being driven by a wire-feed motor
(2); a control box (9) controlling the wire - feed motor (2); at least two power
sources (10,11) respectively providing via the first terminals to the first and
second torches (3A, 3B); a job (12) connectable to the second terminals of the
power sources (10, 11); the wires fed to the two torches (3A, 3B) coming-out of
each contact tip (4) to create an arc (5) under flux blanket (6) to form a single
weld pool (7).

Documents:

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Patent Number

278751

Indian Patent Application Number

571/KOL/2008

PG Journal Number

54/2016

Publication Date

30-Dec-2016

Grant Date

29-Dec-2016

Date of Filing

20-Mar-2008

Name of Patentee

BHARAT HEAVY ELECTRICALS LIMITED

Applicant Address

REGIONAL OPERATIONS DIVISION (ROD), PLOT NO: 9/1 DJBLOCK, 3RD FLOOR, KARUNAMOYEE, SALT LAKE CITY, KOLKATA-700091 BHEL HOUSE, SIRI FORT, NEW DELHI- 110049

Inventors:

#	Inventor's Name	Inventor's Address
1	KRISHNASWAMI PADMANABAN	WELDING RESEARCH INSTITUTE, BHEL, TIRUCHIRAPPALLI-620014
2	MANNARSAMY RAMAKRISHNAN	WELDING RESEARCH INSTITUTE, BHEL, TIRUCHIRAPPALLI-620014
3	POOSARI PERIASAMY	WELDING RESEARCH INSTITUTE, BHEL, TIRUCHIRAPPALLI-620014
4	SIVASANKARAN MANOHARAN	WELDING RESEARCH INSTITUTE, BHEL, TIRUCHIRAPPALLI-620014

PCT International Classification Number

B23K9/00; B23K9/18

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA