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 |
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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. -3- 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. -4- 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. -5- 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 -6- 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 -7- 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 -8- 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. -9- 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; -10- - 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. -11- 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. |
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01066-kol-2007-correspondence others 1.1.pdf
01066-kol-2007-correspondence others.pdf
01066-kol-2007-description complete.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
Patent Number | 257844 | ||||||||||||
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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 | ||||||||||||
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PCT International Classification Number | B23K9/00 | ||||||||||||
PCT International Application Number | N/A | ||||||||||||
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