Indian Patents. 253394:AN IMPROVED TORCH FOR NARROW GAP GAS METAL ARC WELDING

Title of Invention	AN IMPROVED TORCH FOR NARROW GAP GAS METAL ARC WELDING
Abstract	Accordingly, there is provided an improved torch for narrow gap - gas metal arc welding comprising a central tubular member for feeding a wire, an water inlet tube, a water outlet tube, a gas inlet tube, a first solid block to hold atleast one contact tip, a plurality of outer flattened tubes for gas shielding and a second solid block to hold the tubes.

Full Text	FIELD OF THE INVENTION The invention relates to an improved torch for welding in narrow groove joints using Gas Metal Are Welding process (GMAW). BACKGROUND OF THE INVENTION In order to improve the productivity in thick section material welding, several techniques are employed. One of the important techniques of interest is the use of narrower joint grooves. The conventional welding makes use of typical joint edge preparation indicated in Fig. 1. As compared to this, the narrow gap welding employs near parallel sided edge preparation. The included angle of joint will be in the range of 1-2 degree as shown in Fig.2. The principal welding processes normally employed for narrow gap welding are Submerged arc welding (SAW), Gas Metal arc welding (GMAW), Gas Tungsten are welding (GTAW) and Electrogas Welding (EGW). In some countries, narrow gap Sumerged arc welding is preferred because of the easy avaliability of equipment and the familiarization with SAW for thick section welding. In some other countries, narrow gap gas metal arc welding is used to greater extent due to the overall cleanliness, better quality welding associated with this process and lesser gap compared to SAW. The width of the joint at the root is required to be maintained at 10-12 mm depending upon the thickness of the material and the technique employed with GMAW process. Accordingly the thickness of the GMAW torch plays an important role in decreasing the gap of joint at the root i.e. lesser the thickness of torch, it will better reduce the gap of joint leading to less volume of weld metal. 1 Narrow gap - Gas metal arc welding (NG-GMAW) differs from the conventional GMAW process in two ways, for example, in providing a wire feeding mechanism to ensure reliable sidewall fusion and the capacity of tne torch to provide adequate gas shielding to the are zone. In all advanced narrow gap GMAW equipments, the welding torch is placed inside the joint to be welded. There are many variations in this type. However, one technique, which is most widely used, is related to bending of the wire in sinusoidal waveform to oscillate the are across the joint gap to achieve an adequate sidewall fusion. The other requirement is to ensure quality weld joints devoid of defects like porous beads, lack of fusion, lack of penetration, blow holes etc. in weld zone. Patent WO 98/ 00265 relates in particular to a process titled "Process for Narrow -Gap welding by the MAG arc welding process" in which the welding device is conveyed in the welding groove, and consequently at least one fusion wire electrode guided through a contact tube is delivered with inert gas to the welding zone at a predetermined wire feed rate. The arc produced between the wire electrode and the workpiece should be formed alternately with respect to the two workpiece edges Eo ensure good welding seam quality, which used to be achieved by which rotation adjusts at particular welding parameters. Patent No. JP7116852 discloses a torch for narrow gap MIG welding and welding method thereof capable of obtaining stable good quality wetd zone without generating welding defects of blowhole, incomplete penetration, etc., in weld zone. The torch has a typical constitution wherein an oval shaped hole for the shield gas injection ports for welding is provided for, improving spreading of shield gas, further a hole of a contact tip of torch is made to oval, by always setting a weaving direction of a welding wire in the fixed direction, high quality wetd zone is obtained etc., also, the welding wire is weaved in the fixed direction. 2 Patent N0.JP41 58983 describes a torch for narrow gap welding to improve a gas shielding effect by providing an outside shielding gas hole vertically on the outside of a torch main body and providing a deflecting means to guide gas outward on the opposite part of a tip exhaust nozzle thereof. A welding wire is introduced from a wire introduction port of the torch main body and power is supplied from a contact chip and an arc is generated at an interval with materials to be welded to perform welding. Patent No. EP01953410 discloses a torch for welding a narrow groove gap joint wherein a welding torch is described comprising a tip with a through slot in which a welding wire is inserted. Said slot has a end section which diverges from the main axis A-A and is curved, such that the welding rod extends out of said end section at a predetermined angle. The tip's axis of rotation is parallel to the joint's axis of symmetry. The tip can also be translated by a suitable actuating means so as to alter its distance from the walls of the joint OBJECTS OF THE INVENTION It is therefore an object the of invention to propose an improved, torch for gas metal arc welding in a narrow groove joints having means for feeding a waved wire and thereby providing adequate gas shielding to perform narrow gap gas metal arc welding (NG-GMAW) without any mechanical rotation of the wire or wire guide and thus avoiding complicated machining operations and eliminating disadvantages of prior art. Another object of the invention is to propose an improved torch for gas metal arc welding in a narrow groove joints which is capable to operate in grooves having 10-12 mm, and joint thickness upto 250mm. 3 Still another object of the invention is to propose an improved torch for gas metal arc welding in a narrow groove joints which is sleek and fight-weighted and having a simple construction. A still further object of the invention is to propose an improved torch for gas metal ere welding in a narrow groove joints which is easily mountable on a wire feeding means. A still another object of the invention is to propose an improved torch for gas metal arc welding in a narrow groove joints which has sufficient rigidity and stability in carrying out the welding operations. An yet another object of the invention is to propose an improved torch for gas rnetal arc welding in a narrow groove joints which is so configured to allow easy wrapping of insulating tape over the affected area to avoid any stray arcing during welding operation. SUMMARY OF THE INVENTION Accordingly, there is provided an improved torch for narrow gap - gas metal arc welding comprising a central tubular member for feeding a wire; an water intet tube; a water outlet tube, a gas inlet tube, a first solid block to hofd atleast one contact tip, a plurality of outer flattened tubes for gas shielding and a second solid block to hold the tubes. BRIEF DESCRIPTION OF THE ACCOMAPNYING DRAWINGS Fig-l A schematic representation of edge preparation for conventional Gas Metal Arc welding 4 Fig-2 schematically shows an edge preparation for Narrow Gap Gas Metal Arc welding according to prior art. Fig-3 shows schematic sketch of an improved torch for carrying out gas metal arc welding (GMAW) in narrow groove joints according to the invention. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION Fig. 1 shows a typical edge preparation employed for one side conventional gas metal arc welding. The material to be joined is machined to have a J groove edge preparation. When the two halves of the joints are assembled, it forms a groove with an included angle of (D) equaling 20 °. The bottom of the groove has a radius of 9 mm (C) thus making a joint of 18mm gap. The root thickness (B) can vary between 3-5mm depending upon the current level employed. The thickness of joint (A) can vary up to 150 to 250 mm. Generally, such edge preparation requires a backing plate being tack welded on the reverse side to support the molten weld metal created by the welding arc. Fig-2 shows a typical edge preparation employed for one side Narrow gap gas metal arc welding. The material to be joined is machined to have a J groove eage preparation. When the two halves of the joints are assembled, it forms a groove with an included angle (D) equaling 1 to 2 °. The bottom of the groove has a radius of 6 ram (C) thus making joint of 12mm gap. The root thickness (B) can vary between 3-5mm depending upon the current level employed. The thickness of joint (A) can vary up to 150 to 250 mm. As shown in Fig. 3 - the improved narrow gap torch is attached to a wire feeding means (not shown) to facilitate smooth travel of an wire in a center of the torch through a copper tube (1). Two flattened copper tubes (5) are attached to both sides of the copper tube (1) to provide gas shielding over the welding area. The 5 central copper tube (1) is attached to a first solid block (7) of copper where a contact tip is attached. The first solid block (7) is water cooled through an inlet tube (2) and an outlet tube (3). All the copper tubes (1,2,3,5) are attached to a second solid copper block (6) on the top. The second solid block (6) is drilled suitably to house the copper tubes (1,2,3) including the connectors (4) to provide water-cooling and gas shielding. The overall thickness of the torch is kept within 7 mm. Apart from primary shielding near the arc, the arc zone requires secondary shielding to avoid induction of air. It can be insulated easily by high temperature insulation tape to avoid any arcing during the welding. 6 WE CLAIM 1. An improved torch for narrow gap - gas metal art welding comprising s central tubular member (1) for feeding a wire; - an water inlet tube (2); and - an water outlet tube (3), a gas inlet tube, a first solid block (7) to noid atleast one contact tip, a plurality of outer flattened tubes (5) for gas shielding and a second solid block (6) to hold tne tubes (1,5). 2. The torch as claimed in claim 1, wherein the second solid block (6) is provided with a plurality of drilled holes to accommodate the copper tubes (1,2,3,5), 3. The torch as claimed in claim 1 or 2, wherein a plurality of connectors (4) are arranged on the second solid block (6) to provide water-cooling and gas- shielding. 4. An improved torch for narrow gap - gas metal arc welding as substantially described herein with reference to the accompanying drawings. 7

Full Text

FIELD OF THE INVENTION
The invention relates to an improved torch for welding in narrow groove joints
using Gas Metal Are Welding process (GMAW).
BACKGROUND OF THE INVENTION
In order to improve the productivity in thick section material welding, several
techniques are employed. One of the important techniques of interest is the use
of narrower joint grooves. The conventional welding makes use of typical joint
edge preparation indicated in Fig. 1. As compared to this, the narrow gap welding
employs near parallel sided edge preparation. The included angle of joint will be
in the range of 1-2 degree as shown in Fig.2. The principal welding processes
normally employed for narrow gap welding are Submerged arc welding (SAW),
Gas Metal arc welding (GMAW), Gas Tungsten are welding (GTAW) and
Electrogas Welding (EGW). In some countries, narrow gap Sumerged arc
welding is preferred because of the easy avaliability of equipment and the
familiarization with SAW for thick section welding. In some other countries,
narrow gap gas metal arc welding is used to greater extent due to the overall
cleanliness, better quality welding associated with this process and lesser gap
compared to SAW.
The width of the joint at the root is required to be maintained at 10-12 mm
depending upon the thickness of the material and the technique employed with
GMAW process. Accordingly the thickness of the GMAW torch plays an important
role in decreasing the gap of joint at the root i.e. lesser the thickness of torch, it
will better reduce the gap of joint leading to less volume of weld metal.
1

Narrow gap - Gas metal arc welding (NG-GMAW) differs from the conventional
GMAW process in two ways, for example, in providing a wire feeding mechanism
to ensure reliable sidewall fusion and the capacity of tne torch to provide
adequate gas shielding to the are zone. In all advanced narrow gap GMAW
equipments, the welding torch is placed inside the joint to be welded. There are
many variations in this type. However, one technique, which is most widely
used, is related to bending of the wire in sinusoidal waveform to oscillate the are
across the joint gap to achieve an adequate sidewall fusion. The other
requirement is to ensure quality weld joints devoid of defects like porous beads,
lack of fusion, lack of penetration, blow holes etc. in weld zone.
Patent WO 98/ 00265 relates in particular to a process titled "Process for Narrow
-Gap welding by the MAG arc welding process" in which the welding device is
conveyed in the welding groove, and consequently at least one fusion wire
electrode guided through a contact tube is delivered with inert gas to the
welding zone at a predetermined wire feed rate. The arc produced between the
wire electrode and the workpiece should be formed alternately with respect to
the two workpiece edges Eo ensure good welding seam quality, which used to be
achieved by which rotation adjusts at particular welding parameters.
Patent No. JP7116852 discloses a torch for narrow gap MIG welding and welding
method thereof capable of obtaining stable good quality wetd zone without
generating welding defects of blowhole, incomplete penetration, etc., in weld
zone. The torch has a typical constitution wherein an oval shaped hole for the
shield gas injection ports for welding is provided for, improving spreading of
shield gas, further a hole of a contact tip of torch is made to oval, by always
setting a weaving direction of a welding wire in the fixed direction, high quality
wetd zone is obtained etc., also, the welding wire is weaved in the fixed
direction.
2

Patent N0.JP41 58983 describes a torch for narrow gap welding to improve a gas
shielding effect by providing an outside shielding gas hole vertically on the
outside of a torch main body and providing a deflecting means to guide gas
outward on the opposite part of a tip exhaust nozzle thereof. A welding wire is
introduced from a wire introduction port of the torch main body and power is
supplied from a contact chip and an arc is generated at an interval with materials
to be welded to perform welding.
Patent No. EP01953410 discloses a torch for welding a narrow groove gap joint
wherein a welding torch is described comprising a tip with a through slot in
which a welding wire is inserted. Said slot has a end section which diverges from
the main axis A-A and is curved, such that the welding rod extends out of said
end section at a predetermined angle. The tip's axis of rotation is parallel to the
joint's axis of symmetry. The tip can also be translated by a suitable actuating
means so as to alter its distance from the walls of the joint
OBJECTS OF THE INVENTION
It is therefore an object the of invention to propose an improved, torch for gas
metal arc welding in a narrow groove joints having means for feeding a waved
wire and thereby providing adequate gas shielding to perform narrow gap gas
metal arc welding (NG-GMAW) without any mechanical rotation of the wire or
wire guide and thus avoiding complicated machining operations and eliminating
disadvantages of prior art.
Another object of the invention is to propose an improved torch for gas metal
arc welding in a narrow groove joints which is capable to operate in grooves
having 10-12 mm, and joint thickness upto 250mm.
3

Still another object of the invention is to propose an improved torch for gas
metal arc welding in a narrow groove joints which is sleek and fight-weighted
and having a simple construction.
A still further object of the invention is to propose an improved torch for gas
metal ere welding in a narrow groove joints which is easily mountable on a wire
feeding means.
A still another object of the invention is to propose an improved torch for gas
metal arc welding in a narrow groove joints which has sufficient rigidity and
stability in carrying out the welding operations.
An yet another object of the invention is to propose an improved torch for gas
rnetal arc welding in a narrow groove joints which is so configured to allow easy
wrapping of insulating tape over the affected area to avoid any stray arcing
during welding operation.
SUMMARY OF THE INVENTION
Accordingly, there is provided an improved torch for narrow gap - gas metal arc
welding comprising a central tubular member for feeding a wire; an water intet
tube; a water outlet tube, a gas inlet tube, a first solid block to hofd atleast one
contact tip, a plurality of outer flattened tubes for gas shielding and a second
solid block to hold the tubes.
BRIEF DESCRIPTION OF THE ACCOMAPNYING DRAWINGS
Fig-l A schematic representation of edge preparation for conventional Gas Metal
Arc welding
4

Fig-2 schematically shows an edge preparation for Narrow Gap Gas Metal Arc
welding according to prior art.
Fig-3 shows schematic sketch of an improved torch for carrying out gas metal
arc welding (GMAW) in narrow groove joints according to the invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
Fig. 1 shows a typical edge preparation employed for one side conventional gas
metal arc welding. The material to be joined is machined to have a J groove
edge preparation. When the two halves of the joints are assembled, it forms a
groove with an included angle of (D) equaling 20 °. The bottom of the groove
has a radius of 9 mm (C) thus making a joint of 18mm gap. The root thickness
(B) can vary between 3-5mm depending upon the current level employed. The
thickness of joint (A) can vary up to 150 to 250 mm. Generally, such edge
preparation requires a backing plate being tack welded on the reverse side to
support the molten weld metal created by the welding arc.
Fig-2 shows a typical edge preparation employed for one side Narrow gap gas
metal arc welding. The material to be joined is machined to have a J groove
eage preparation. When the two halves of the joints are assembled, it forms a
groove with an included angle (D) equaling 1 to 2 °. The bottom of the groove
has a radius of 6 ram (C) thus making joint of 12mm gap. The root thickness (B)
can vary between 3-5mm depending upon the current level employed. The
thickness of joint (A) can vary up to 150 to 250 mm.
As shown in Fig. 3 - the improved narrow gap torch is attached to a wire feeding
means (not shown) to facilitate smooth travel of an wire in a center of the torch
through a copper tube (1). Two flattened copper tubes (5) are attached to both
sides of the copper tube (1) to provide gas shielding over the welding area. The
5

central copper tube (1) is attached to a first solid block (7) of copper where a
contact tip is attached. The first solid block (7) is water cooled through an inlet
tube (2) and an outlet tube (3). All the copper tubes (1,2,3,5) are attached to a
second solid copper block (6) on the top. The second solid block (6) is drilled
suitably to house the copper tubes (1,2,3) including the connectors (4) to
provide water-cooling and gas shielding. The overall thickness of the torch is
kept within 7 mm. Apart from primary shielding near the arc, the arc zone
requires secondary shielding to avoid induction of air. It can be insulated easily
by high temperature insulation tape to avoid any arcing during the welding.
6

WE CLAIM
1. An improved torch for narrow gap - gas metal art welding comprising s
central tubular member (1) for feeding a wire;
- an water inlet tube (2); and
- an water outlet tube (3), a gas inlet tube, a first solid block (7) to
noid atleast one contact tip, a plurality of outer flattened tubes (5)
for gas shielding and a second solid block (6) to hold tne tubes
(1,5).
2. The torch as claimed in claim 1, wherein the second solid block (6) is
provided with a plurality of drilled holes to accommodate the copper tubes
(1,2,3,5),
3. The torch as claimed in claim 1 or 2, wherein a plurality of connectors (4)
are arranged on the second solid block (6) to provide water-cooling and
gas- shielding.
4. An improved torch for narrow gap - gas metal arc welding as substantially
described herein with reference to the accompanying drawings.

7

Documents:

00272-kol-2006-claims.pdf

00272-kol-2006-description complete.pdf

00272-kol-2006-drawings.pdf

00272-kol-2006-form 1.pdf

00272-kol-2006-form 2.pdf

00272-kol-2006-form 3.pdf

00272-kol-2006-gpa.pdf

272-KOL-2006-ABSTRACT 1.1.pdf

272-kol-2006-abstract 1.2.pdf

272-KOL-2006-ABSTRACT.pdf

272-KOL-2006-AMANDED CLAIMS 1.1.pdf

272-kol-2006-amanded claims 1.2.pdf

272-KOL-2006-AMANDED CLAIMS.pdf

272-KOL-2006-CANCELLED PAGES.pdf

272-KOL-2006-CORRESPONDENCE 1.1.pdf

272-kol-2006-correspondence 1.2.pdf

272-KOL-2006-CORRESPONDENCE 1.3.pdf

272-KOL-2006-CORRESPONDENCE.pdf

272-KOL-2006-DESCRIPTION (COMPLETE) 1.2.pdf

272-KOL-2006-DESCRIPTION (COMPLETE).1.1.pdf

272-KOL-2006-DRAWINGS 1.2.pdf

272-KOL-2006-DRAWINGS.1.1.pdf

272-KOL-2006-EXAMINATION REPORT.pdf

272-KOL-2006-FORM 1 1.2.pdf

272-kol-2006-form 1 1.3.pdf

272-KOL-2006-FORM 1.1.1.pdf

272-KOL-2006-FORM 18.pdf

272-KOL-2006-FORM 2 1.2.pdf

272-kol-2006-form 2 1.3.pdf

272-KOL-2006-FORM 2.1.1.pdf

272-KOL-2006-FORM 3.pdf

272-KOL-2006-GPA.pdf

272-KOL-2006-GRANTED-ABSTRACT.pdf

272-KOL-2006-GRANTED-CLAIMS.pdf

272-KOL-2006-GRANTED-DESCRIPTION (COMPLETE).pdf

272-KOL-2006-GRANTED-FORM 1.pdf

272-KOL-2006-GRANTED-FORM 2.pdf

272-KOL-2006-GRANTED-LETTER PATENT.pdf

272-KOL-2006-GRANTED-SPECIFICATION.pdf

272-KOL-2006-OTHERS 1.1.pdf

272-kol-2006-others 1.2.pdf

272-KOL-2006-OTHERS 1.3.pdf

272-KOL-2006-PA.pdf

272-KOL-2006-REPLY TO EXAMINATION REPORT 1.1.pdf

272-KOL-2006-REPLY TO EXAMINATION REPORT.pdf

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Patent Number

253394

Indian Patent Application Number

272/KOL/2006

PG Journal Number

29/2012

Publication Date

20-Jul-2012

Grant Date

18-Jul-2012

Date of Filing

27-Mar-2006

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, HAVING ITS REGISTERED OFFICE AT BHEL HOUSE, SIRI FORT, NEW DELHI-110049, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	KRISHNASWAMY PADMANABAN	WELDING RESEARCH INSTITUTE, BHEL, TIRUCHY-620014
2	KANHAIYALAL ROHIRA	WELDING RESEARCH INSTITUTE, BHEL, TIRUCHY-620014

PCT International Classification Number

B23K 9/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA