Title of Invention

AN IMPROVED SINGLE/TANDEM WIRE SUBMERGED ARC WELDING MACHINE FOR BUTT JOINT AND HARDFACING IN GROOVES WITH WIDTH OF DIFFERENT SIZES AND A HIGH DILLUTION PROCESS

Abstract The invention relates to an improved single/tandem wire submerged arc welding machine for butt joint/ hardfacing of similar/different combination of filler wires, the improvement is with two nozzles (4) is at least one additional two-wire feeder means (2) with two nozzles (4) is provided to a conventional submerged arc welding machine so as to achieve a synchronous operation of the existing and the additional wire feeder means (2) both being mounted on an integrated shaft (3); and the wire feeder means having a single control device drawing power from a single direct current constant voltage power source such that a single weld pool with new weld chemistry is obtained when dissimilar or similar wire combination is fed via the two wire feeder means.
Full Text -2-
FIELD OF THE INVENTION
The invention relates to a synergic tandem wire SAW process using two different
wire feeders assembly in a single motor shaft with a single Direct current
constant voltage power source for butt joint/ hardfacing of different combination
of filler wires by adapting an improved single/tandem wire submerged arc
welding machine.
BACKGROUND OF THE INVENTION
A conventional tandem submerged arc welding equipment is essentially
characterized by the adaptation of one additional wire feeder with an Alternate
Current power source which is synchronized with a Direct current constant
voltage power source, a wire feeder with control system controlling the wire feed
rate and delivering the two different DC/AC arcs simultaneously using said two
different power sources for butt joint or hard facing of different or same
combination of filler wires.
In conventional tandem SAW process the heat input energy is calculated by the
average energy of two different DC/AC arcs, and thus less plate is melted as
wire.

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When two welding arcs are running close together, an anomally known as "arc
blow" occurs as the magnetic fields created by the high currents repel each other
and actually blow molten metal out of the weld puddle.
Conventional welding equipment is limited to phase relationship only but without
the ability of phase synchronization.
United States Patent 7166818 discloses 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 rectified 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, and 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.

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United States Patent 4,572,936 discloses a method for making multiple wire
welding in a submerged arc multiple wire welding system. In the method, only
one or two of the welding wires used are over or microalloyed wires. The other
wires are commercially available unalloyed or low-alloyed solid wires. The
process produces a weld metal, which has unexpectedly high toughness values,
and can be performed more economically. This multiple wire welding system is
used in single or multiple-pass welding operations.
In absence of further description in US 4572936, it appears that the wires are
separately fed using different power sources and different wire feeders as
mentioned in the Examples 1 to 4 of US patent. " The first wire is connected to
810 A at 30 V. The second wire is connected at 790 A at 33 V. The third wire is
connected to 680 A at 34 V.
OBJECTS OF THE INVENTION
It is therefore, an object of the present invention to propose a synergic tandem
wire SAW process for butt joints which reduces the cycle time.
Another object of the present invention is to propose an improved single/tandem
wire submerged arc welding equipment which can be adapted in the process.
A still another object of the present invention is to propose a synergic tandem
wire SAW process which has the ability to avoid arc blow.

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A further object of the present invention is to propose a synergic tandem wire
saw process for hardfacing of similar/dissimilar fillers using tandem wires
technique which is capable of creating a common weld pool to achieve a new
deposit chemistry according to the code of highest quality welds, including
achieving a considerable manufacturing economics.
Yet another object of the present invention is to propose an improved welding
equipment which can be configured by interfacing one additional wire feeder
roller and torch along with the main wire feeder with the existing control system
and drive motor using single direct current constant voltage power source.
SUMMARY OF THE INVENTION
In the synergic tandem submerged arc welding process, a newly designed wire
feeder (R), the existing main wire, and an additional wire are fed simultaneously
using two different feeder assemblies and nozzles. The wires in the contact
nozzles are arranged tangential to the welding direction.
With the new synergic tandem SAW process the two DC arcs calculate the heat
input energy. It is therefore a high dilution process with approximately twice as
much plates are being melted as wire. This new synergic tandem SAW process is
one of the advanced techniques which makes use of single power source energy
available in the arc stream, and which increases the deposition rate equivalent to
that of a conventional tandem SAW process. Thus, the new synergic tandem

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SAW can ensure increased transfer efficiency as compared to the other method.
The SYNERGIC TANDEM Arc system provides two arcs, which can be configured
as DC single power source system. The advantage of the SYNERGIC TANDEM
system is the control over the phase relationship.
The SYNERGIC TANDEM has the ability to synchronize the phase relationships
between multiple arcs allowing unprecedented control over the arc blow.
This results in a highest usable melting rate for given arc energy for good
penetration without arc blow. Thus the synergic tandem SAW technique will
result in 40% increase in deposition rate and better mechanical properties is
achievable over conventional Tandem submerged arc welding process. In new
synergic tandem SAW, for addition of one wire is required to interface one
additional wire feeder along with main wire feeder with the existing control
system in same wire feeder motor using single Direct current constant voltage
power source to attain the required chemistry and mechanical properties.
The invention is directed to a further development that, "The similar/dissimilar
wires combination as main wire and an additional wire fed simultaneously using
two different wire feeder assemblies and nozzles in a single integrated wire
feeder motor shaft with same control system drawing power from a single Direct
current constant power source with parameters of 800 A, 32 V and 0.5 m/min as
welding speed". The wires in the contact nozzles are arranged tangential to the
welding direction creating a single weld pool in which the required weld

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chemistry were obtained from the use of two wires of different/same chemistry.
The results are savings in consumables cost, cycle time reduction and high
productivity.
The present invention produces a weld metal structure with a high proportion of
acicular structure, the surface proportions of acicular being 100 percent. The
inventive process performs a multi layer pass welding for reducing the number of
layers compared to conventional SAW process to enhance the mechanical
properties.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig. 1 is prospective view of an improved single/tandem wire submerged arc
welding machine adaptable to a synergic tandem wire SAW process for butt
welding/hardfacing.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
As shown in Fi.-1, an improved wire feeding system can be fitted to a
conventional submerged arc welding machine. The new machine essentially
allows achievement of same/different composition (1) of filler materials and weld
metal combination. The synchronous operation of two wire feeders (2) mounted
on an integral shaft (3) is shown in Fig 1. The dissimilar/similar wire combination

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is fed using a two wire feeder assembly (2) with two nozzles (4) connected to a
single power source (6) which is coupled by a power cable (7) in parallel. A
single weld pool is created in which new weld chemistry is obtained by using two
wires of different chemistry. To attain the required hardness properties as well as
the required microstructure of the weld metal chemistry, twin submerged arc
welding can be used in which the common arc pool (5) is created. In the arc
cavity the filler wires with different/same chemical composition wires are fed
simultaneously in a two nozzle structure, as shown in Fig. 1.
By using the present invention, the welding current for heavy plates welding can
be between about 200 amperes to about 1250 amperes.
In accordance with the invention, the electric arc welder includes a first and
second consumable electrode, which electrodes are moved in unison along a
welding path between the edges of the grounded plate. Power supply from one
power source (6) is used for passing welding currents between the individual
electrodes and the plates forming the grounded work piece of the welding circuit.
The new design enables welding/surfacing to be carried out in grooves having a
width of different sizes. The new tandem submerged arc welding with special
wire feeder can be used for welding/hardfacing of butt joints and surfacing. This
technique can be used for both mechanized and as well as automatic mode. This
results in savings in flux cost, cycle time reduction and higher productivity.

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WE CLAIM:
1. An improved single/tandem wire submerged arc welding machine for
butt joint/ hardfacing of similar/different combination of filler wires,
the improvement is characterized in that:
- at least one additional two-wire feeder means (2) with two
nozzles (4) is provided to a conventional submerged arc welding
machine so as to achieve a synchronous operation of the
existing and the additional wire feeder means (2) both being
mounted on an integrated shaft (3); and
- the wire feeder means (2) having a single control device
drawing power from a single direct current constant voltage
power source such that a single weld pool with new weld
chemistry is obtained when dissimilar or similar wire
combination is fed via the two wire feeder means (2).
2. A synergic tandem wire SAW process for butt joint/hardfacing of
different combination of filler wires, the process comprising the steps
of:
- providing an improved single/tandem wire submerged arc
welding machine;
- simultaneously feeding a similar/dissimilar wires combination as
main wire and addition wire via the two different wire feeder
means;

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- arranging the wires in the respective contact nozzles tangential
to the welding direction;
- allowing a common control device for both the wire feeder
means to draw power from a single direct current constant
voltage power source; and
- creating a single weld pool with new weld chemistry.

3. The process as claimed in claim 2, wherein the phase relationships
between multiple arc is synchronized to achieve a substantial control
over arc blow.
4. The process as claimed in claim 2 or 3, wherein the common weld pool
achieves higher deposition and reduced cycle time.
5. The process as claimed in any of the preceding claims, wherein a weld
metal structure is produced with a high proportion of acicular
structure.
6. The process as claimed in claim 5, wherein the surface proportion of
the acicular structure is 100 percent.

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7. The process as claimed in claim 2, wherein a multilayer pass welding is
performed for reducing the number of layers compared to conventional
SAW process.

The invention relates to an improved single/tandem wire submerged arc welding
machine for butt joint/ hardfacing of similar/different combination of filler wires,
the improvement is with two nozzles (4) is at least one additional two-wire
feeder means (2) with two nozzles (4) is provided to a conventional submerged
arc welding machine so as to achieve a synchronous operation of the existing
and the additional wire feeder means (2) both being mounted on an integrated
shaft (3); and the wire feeder means having a single control device drawing
power from a single direct current constant voltage power source such that a
single weld pool with new weld chemistry is obtained when dissimilar or similar
wire combination is fed via the two wire feeder means.

Documents:

01066-kol-2007-abstract.pdf

01066-kol-2007-claims.pdf

01066-kol-2007-correspondence others 1.1.pdf

01066-kol-2007-correspondence others.pdf

01066-kol-2007-description complete.pdf

01066-kol-2007-drawings.pdf

01066-kol-2007-form 1.pdf

01066-kol-2007-form 18.pdf

01066-kol-2007-form 2.pdf

01066-kol-2007-form 3.pdf

01066-kol-2007-gpa.pdf

1066-KOL-2007-(06-02-2012)-ABSTRACT.pdf

1066-KOL-2007-(06-02-2012)-AMANDED CLAIMS.pdf

1066-KOL-2007-(06-02-2012)-DRAWINGS.pdf

1066-KOL-2007-(06-02-2012)-EXAMINATION REPORT REPLY RECEIVED.pdf

1066-KOL-2007-(06-02-2012)-FORM-1.pdf

1066-KOL-2007-(06-02-2012)-FORM-3.pdf

1066-KOL-2007-(06-02-2012)-OTHERS.pdf

1066-KOL-2007-(08-05-2012)-ABSTRACT.pdf

1066-KOL-2007-(08-05-2012)-AMANDED CLAIMS.pdf

1066-KOL-2007-(08-05-2012)-AMANDED PAGES OF SPECIFICATION.pdf

1066-KOL-2007-(08-05-2012)-CORRESPONDENCE.pdf

1066-KOL-2007-(08-05-2012)-DESCRIPTION (COMPLETE).pdf

1066-KOL-2007-(08-05-2012)-FORM-1.pdf

1066-KOL-2007-(08-05-2012)-FORM-2.pdf

1066-KOL-2007-(18-06-2012)-AMANDED CLAIMS.pdf

1066-KOL-2007-(18-06-2012)-CORRESPONDENCE.pdf

1066-KOL-2007-CORRESPONDENCE 1.1.pdf

abstract-01066-kol-2007.jpg


Patent Number 257844
Indian Patent Application Number 1066/KOL/2007
PG Journal Number 46/2013
Publication Date 15-Nov-2013
Grant Date 11-Nov-2013
Date of Filing 31-Jul-2007
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 MANNARSAMY RAMAKRISHNAN NOT AVAILABLE
2 GANAPATHY UMASHANKER NOT AVAILABLE
3 KRISHNASAMY PADMANABAN NOT AVAILABLE
PCT International Classification Number B23K9/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA