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WO1996001717A1 - Soudage a electrode de tungstene par fil d'apport froid, concentrique - Google Patents

Soudage a electrode de tungstene par fil d'apport froid, concentrique Download PDF

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Publication number
WO1996001717A1
WO1996001717A1 PCT/US1995/008472 US9508472W WO9601717A1 WO 1996001717 A1 WO1996001717 A1 WO 1996001717A1 US 9508472 W US9508472 W US 9508472W WO 9601717 A1 WO9601717 A1 WO 9601717A1
Authority
WO
WIPO (PCT)
Prior art keywords
filler wire
nonconsumable electrode
torch head
source
wire guide
Prior art date
Application number
PCT/US1995/008472
Other languages
English (en)
Inventor
Larry W. Cherne
David A. Cherne
Original Assignee
Cherne Larry W
Cherne David A
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Cherne Larry W, Cherne David A filed Critical Cherne Larry W
Priority to AU29627/95A priority Critical patent/AU2962795A/en
Publication of WO1996001717A1 publication Critical patent/WO1996001717A1/fr

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00—Arc welding or cutting
    • B23K9/16—Arc welding or cutting making use of shielding gas
    • B23K9/167—Arc welding or cutting making use of shielding gas and of a non-consumable electrode

Definitions

  • the present invention relates to cold wire gas tungsten arc welding, and more particularly to a welding method that uses a torch with the wire guide concentrically disposed within the torch at the central longitudinal axis and the tungsten electrode is offset from that axis.
  • the invention can also include placing the tungsten electrode at an angle relative to the filler wire.
  • Background Art Gas tungsten arc welding (GTAW) and more particularly cold wire gas tungsten arc welding (CWGTAW) is a process wherein an electric arc is created between base material to be welded and a nonconsumable tungsten electrode, using either AC or DC ⁇ current.
  • the heat created by the arc melts the base material creating a weld pool into which consumable filler wire is added to add reinforcement, compensate for shrinkage or provide alloys required for the desired results.
  • the filler wire is added to the weld pool as the torch moves along the welding joint.
  • the filler wire In cold wire GTAW the filler wire must be kept electrically cold. In other words, the filler wire must be insulated to prevent the power being supplied to the tungsten electrode from diverting to the filler wire. Further, once the filler wire exits its insulated guide to be placed in the weld pool the filler wire must be kept a controlled distance from the tungsten electrode. If the filler wire is too close to the tungsten electrode, it will be deflected toward the tungsten electrode causing contamination and requiring replacement of the tungsten electrode. The minimum distances required between the filler wire and the tungsten electrode vary with the welding parameters and are known to those skilled in the art.
  • GTAW is further characterized by the use of an inert shielding gas to protect the welding process from oxidation and to aid in electrical conductivity.
  • a shielding gas is fed through the torch and flows from the gas nozzle at the open end of the torch to shield the tungsten electrode and the weld pool and to aid in electrical conductivity.
  • the filler metal must enter the weld pool within the protection of the shielding gas to prevent oxidation.
  • GTAW is the preferred method of welding for certain applications.
  • GTAW is particularly adapted for joining and overlaying aluminum, stainless, magnesium, titanium and tool steel.
  • GTAW is a precise and accurate welding process that produces a high quality weld.
  • MIG Metal Inert Gas
  • GTAW has the advantage of being safer than MIG welding because it produces significantly less metal oxide fumes, some of which, such as Chrome-6 and Nickel oxides, are known carcinogens.
  • GTAW processes can be operator controlled, semi-automatic, or fully automatic.
  • Traditional hand-held fully operator controlled GTAW requires extraordinary skill and dexterity.
  • the operator must hold the welding torch in one hand, hold and feed the filler wire with the other hand while controlling the power supply to the tungsten electrode with his foot or his thumb.
  • the arc length must be held at 0.040 to 0.250 inches in order to maintain a consistent weld. If the operator errs even slightly in positioning the filler wire, the filler metal may deflect and contaminate the tungsten. Time is then wasted having to replace the tungsten electrode.
  • An object of this invention is to improve welding travel speed, deposition rates, weld quality, consistency of deposits, control over the welding process, and the weld types available in cold wire gas tungsten arc welding. Another object is to reduce the level of operator skill needed to perform cold wire GTAW welding.
  • a further object is to provide a lightweight, ergonomic welding torch suitable for hand-held manual, hand-held semiautomatic or automatic cold wire GTAW welding.
  • FIG. 1 is a schematic partial cutaway side view of a welding gun made in accordance with this invention
  • FIG. 2 is an enlarged schematic sectional view of the distal portion of the torch head
  • FIG. 3 is a schematic of the cross-sectional aspects of various prior art welds and various welds made in accordance with this invention
  • FIG. 4 is a schematic perspective exploded view of another embodiment of the welding gun
  • FIG. 5 is a schematic cross-sectional view of the distal portion of another embodiment of the conductive holder
  • FIG. 6 is a schematic sectional view of the distal end of the torch head of another embodiment of this invention.
  • a GTAW welding gun 10 comprises a torch head 12 attached to a neck 14 which is in turn secured to a handle 16.
  • the particular design of the welding gun 10, including the torch head 12, neck 14, and handle 16 are a matter of choice for those skilled in the art.
  • the tungsten electrode 18 is attached to a conductive holder 20 which in turn is secured by a friction fit to the torch head 12 in a manner which preferably allows the conductive holder 20 to be attached and removed from the torch head 12 in order to facilitate replacement of the tungsten electrode 18.
  • the size of the tungsten electrode 18 is predetermined by the operator depending on the application and other factors. Any available size of tungsten electrode 18 can be used with this invention, including the smallest diameters. Further, the tip of the tungsten electrode 18 can be shaped to either a frustro- conical or hemispherical head depending on which is needed for the application.
  • the tungsten electrode 18 can be composed of either pure tungsten or a tungsten alloy containing cerium, lanthanum, thorium, or zirconium, such as, for example, 1% thoriated tungsten, or 2% thoriated rare earth blend.
  • any reference to a tungsten electrode should be understood to include both pure tungsten and tungsten alloy electrodes.
  • the tungsten electrode 18 is disposed on the conductive holder 20 so that when the conductive holder 20 is attached to the torch head 12 the tungsten electrode 18 does not intersect the central longitudinal axis of the torch head 12.
  • the conductive holder 20 can be composed of any type of conductive material such as copper.
  • Electrical current is supplied to the tungsten electrode 18 by the current conductor 22 which extends through the handle 16, neck 14, and the torch head 12 to supply current to the conductive holder 20 which thereby conducts current to the tungsten electrode 18.
  • the power supply is amperage controlled and of the constant current, constant potential current, and/or inverter type with AC and/or DC ⁇ output which are common in the industry.
  • a remote amperage control which can also be programmable, can be used with this invention.
  • the gas nozzle 30 is attached to the torch head 12. Welding must occur within the shielding gas in order to prevent oxidation.
  • the shielding gases useful with this invention are the same as those presently used by the industry with GTAW welding.
  • a hollow cylindrical wire guide 32 composed of nonconductive, low friction material is disposed within the GTAW welding gun 10 and extends to the distal end of the torch head 12 to the location where the conductive holder 20 is attached to the torch head 12.
  • the wire guide 32 can be composed of a material which has a low coefficient of friction, such as teflon, nylon or ceramic, to allow a smooth feeding of the filler wire 36.
  • the wire guide 32 is concentrically disposed within the torch head 12 so that the central longitudinal axis of the wire guide 32 is substantially coaxial with the central longitudinal axis of the torch head 12.
  • a ceramic tube 34 is disposed within the conductive holder 20 and is even with or extends past the distal edge of the conductive holder 20.
  • the ceramic tube 34 is disposed within the conductive holder 20 in a position such that when the conductive holder 20 is attached to the torch head 12 the central longitudinal axis of the ceramic tube 34 is substantially coaxial with the central longitudinal axis of the wire guide 32.
  • the ceramic tube 34 can be composed of a ceramic material or any electrically insulating material that will prevent current from passing from the conductive holder 20 to the filler wire 36.
  • the filler wire 36 is fed through the wire guide 32 and continues through the ceramic tube 34 where it is fed into the weld pool 26 during welding.
  • the filler wire 36 can be fed by an automatic wire feed unit such as the cold wire feed system sold by Jetline, Inc.
  • the filler wire 36 may have a diameter between 0.015 and 0.125 inches and may be composed of any suitable metal composition appropriate for the particular welding application, including stainless, nickels, monels, inconels, steels, aluminum tool steel, bronzes, brass and other designations of the American Welding Society.
  • the concentric or coaxial placement of the wire guide 32 within the torch head 12 leads to many advantages over the prior art.
  • the welding process will be much simpler for the operator because the filler wire 36 is, by design, placed into the proper location in the weld pool 26.
  • the filler wire 36 defines the tool point of the weld.
  • the tool point should travel along the joint to be welded.
  • the filler wire 36 should be inserted at the point where the two base metal pieces to be joined meet.
  • the filler wire 36 is fed from the center of the torch head 12, the operator can more easily keep the tool point on the weld joint.
  • the operator need not be as skilled as is required for traditional GTAW welding.
  • the invention also permits a simple, light weight torch design. Feeding the filler wire 36 concentrically through the welding gun 10 permits an ergonomic design. The operator can hold the welding gun 10 in a comfortable position without added torsional stress being placed on his wrist during welding.
  • the concentric feeding of the filler wire 36 through the welding gun 10 reduces the potential for contamination of the tungsten electrode 18 due to feeding problems.
  • Most spooled wire has a cast, a helix, and a twist which causes the wire to naturally curl.
  • the filler wire 36 will tend to curl more when it is subjected to more force on one side over the other. The smaller the diameter of the wire, the more the wire will curl upon exiting the ceramic tube 34. Feeding the filler wire 36 concentrically reduces the chance that uneven forces will be applied to the filler wire 36 during feeding.
  • the concentric feeding of the filler wire 36 increases welding efficiency and reduces costs by decreasing the chance that the filler wire 36 will deflect and contaminate the tungsten electrode 18.
  • FIG. 3 illustrates the cross-section of various types of welds, including a traditional MIG weld 38, a traditional GTAW weld 40, and three categories of welds that can be achieved by this invention, an alloy transfer weld 41, a buried transfer weld 42, and a plasma transfer weld 43.
  • a traditional MIG weld 38 a traditional GTAW weld 38
  • a traditional GTAW weld 40 three categories of welds that can be achieved by this invention
  • an alloy transfer weld 41 a buried transfer weld 42
  • a plasma transfer weld 43 a plasma transfer weld 43.
  • all three types of welds possible with this invention 41, 42, 43 result in a lower profile weld than is possible with traditional GTAW welding 40.
  • the lower profile reduces manufacturing costs because it requires less grinding to achieve a finished product.
  • the first type of weld possible with this invention is achieved by setting the wire feed speed at a relatively slower rate so that the heat that is reflected back toward the torch from the arc 24 and the weld pool 26 melts the filler wire 36 before it enters the arc 24 or the weld pool 26.
  • the filler wire 36 thus melts and droplets of the molten filler wire 36 fall into the weld pool 26.
  • the weld profile achieved with alloy transfer welding 41 is relatively wide and shallow like the weld profile achieved in traditional MIG welding 38 though with a lower profile. Again, the lower profile reduces manufacturing costs because it requires less grinding to achieve a finished produc .
  • the second type of weld possible with this invention is achieved by increasing the feed speed of the filler wire 36 so that the reflected heat does not have time to melt the filler wire 36.
  • the filler wire 36 can be driven deep into the weld pool 26 achieving a weld profile 42 with a large depth to width ratio.
  • This increased depth to width ratio results in reduced manufacturing costs because less edge preparation is required. Further, energy costs are reduced because less heat input is required to achieve a weld with a larger depth to width ratio.
  • the third type of weld possible with this invention is a plasma transfer weld 43.
  • the wire feed speed is balanced in this process so that the filler wire 36 is not fed so slowly that the reflective heat causes it to melt before entering the arc 24 as with alloy transfer welding 41, yet the wire feed speed is not so fast that the filler wire 36 enters the weld pool 26 before melting as with buried transfer welding 42. Rather the filler wire 36 enters the arc 24, also known as the plasma, which is at a temperature between 6000 and 8000 degrees
  • any size filler wire can be used in plasma transfer welding, although it can be difficult to melt the larger diameter filler wires within the arc or plasma in order to achieve plasma transfer welding.
  • the welding speed is greatly increased in plasma transfer welding 43 because the temperature of the filler wire 36 is increased before being placed in the weld pool 26 thereby reducing the distortion, shrinkage, and, with certain alloys, cracking that is caused when a cold filler wire 36 enters and chills the weld pool 26. Further, the total energy input is reduced because the energy in the arc or plasma 24 is transferred to the filler wire 36 and therefore to the deposit.
  • the depth to width ratio of a plasma transfer weld 43 is also greater than the depth to width ratio possible with traditional GTAW welding 40, though the ratio is not as great as the ratio possible with buried transfer welding 42. Thus, the manufacturing and energy costs are reduced in plasma transfer welding 43.
  • FIGS. 4, 5 and 6 Several other embodiments of this invention are depicted in FIGS. 4, 5 and 6.
  • the welding gun 10 can be designed such that the wire guide 32 is not disposed within the handle 16 but rather is inserted directly into the torch head 12.
  • the neck 14 and the handle 16 are combined in one structure.
  • the shielding gas supply tube 28 and the current conductor 22 enter through the combined neck 14 and handle 16.
  • the ceramic tube 34, the conductive holder 20, the tungsten electrode 18, the gas nozzle 30, and the filler wire 36 are also shown in FIG. 4.
  • This design is less preferable than the design shown in FIG. 1 because the torsional stress placed on the operator's wrist during welding is increased.
  • the preferred embodiment of FIG. 1 minimizes any such torsional stress.
  • FIG. 5 depicts the distal end of another embodiment of the conductive holder 20.
  • the conductive holder 20 can be more conically shaped as shown in FIG. 5, rather than the substantially cylindrical shape as shown in FIG. 2, to facilitate welding when the base metal 25 forms a corner or other similarly restricted joint.
  • the ceramic tube 34 is disposed within the conductive holder 20 such that when the conductive holder 20 is attached to the torch head 12 the longitudinal axis of the ceramic tube 34 is coaxial with both the wire guide 32 and the torch head 12.
  • the gas nozzle 30 surrounds the conductive holder 20.
  • the tungsten electrode 18 is behind and obscured by the filler wire 36 and the ceramic tube 34.
  • the preferred embodiment involves placing the tungsten electrode 18 at an angle to the filler wire 36. Angling the tungsten allows the operator to vary the size and shape of the arc 24 and the weld pool 26, increasing the welding options available and the operator's control over the process.
  • the tungsten electrode 18 is mounted in the conductive holder 20 such that the longitudinal axis of the tungsten electrode 18 forms an angle 44 with the longitudinal axis of the filler wire 36 measured from the point of convergence of their respective axes.
  • the angle 44 can be between negative 10 degrees (-10°) and forty five degrees (45°) .
  • the larger the angle 44 the larger the conductive holder 20 must be in order to accommodate the tungsten electrode 18.
  • the diameter of the gas nozzle 30 may need to be increased to allow for the larger conductive holder 20.
  • the larger angles may only be practical in automatic welding due to the size of the torch required.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • Arc Welding In General (AREA)

Abstract

Cette invention se rapporte à un procédé et à un appareil de soudage à électrode de tungstène par fil d'apport froid. On fait passer ce fil d'apport (36) de manière concentrique dans l'appareil de soudage (10), une électrode réfractaire (18) étant placée loin du centre dans l'appareil de soudage (10). L'électrode réfractaire (18) peut être positionnée parallèlement à ou au niveau d'un angle du fil d'apport (36) en fonction de l'application de soudage.
PCT/US1995/008472 1994-07-08 1995-07-07 Soudage a electrode de tungstene par fil d'apport froid, concentrique WO1996001717A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU29627/95A AU2962795A (en) 1994-07-08 1995-07-07 Concentric cold wire gas tungsten arc welding

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US27226794A 1994-07-08 1994-07-08
US08/272,267 1994-07-08

Publications (1)

Publication Number Publication Date
WO1996001717A1 true WO1996001717A1 (fr) 1996-01-25

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1995/008472 WO1996001717A1 (fr) 1994-07-08 1995-07-07 Soudage a electrode de tungstene par fil d'apport froid, concentrique

Country Status (2)

Country Link
AU (1) AU2962795A (fr)
WO (1) WO1996001717A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997040955A1 (fr) * 1996-04-29 1997-11-06 Westinghouse Electric Corporation Appareil et procede de soudage perfectionnes
FR2809039A1 (fr) * 2000-05-19 2001-11-23 Europ De Tech Torche ergonomique pour la soudure sous atmosphere de gaz inerte de type t.i.g. et son procede de montage
CN107186322A (zh) * 2017-06-29 2017-09-22 沈阳工业大学 半裂式空心钨极同轴送丝惰性气体保护焊焊枪
WO2020115033A1 (fr) * 2018-12-05 2020-06-11 Framatome Torche de soudage et procédé de fabrication correspondant

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4879446A (en) * 1988-12-05 1989-11-07 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Internal wire guide for GTAW welding
SU1614903A1 (ru) * 1988-07-05 1990-12-23 Предприятие П/Я А-1122 Головка дл автоматической дуговой сварки

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU1614903A1 (ru) * 1988-07-05 1990-12-23 Предприятие П/Я А-1122 Головка дл автоматической дуговой сварки
US4879446A (en) * 1988-12-05 1989-11-07 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Internal wire guide for GTAW welding

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
DATABASE WPI Week 9135, 16 October 1991 Derwent World Patents Index; AN 91258352, "Torch for automatic arc welding - has bushing with spherical top surface, channel for filler wire in bowden jacket, and eccentric nut for fixing electrode." *
SHTRIKMAN ET AL.: "Automatic argon-arc welding with shunting the arc with filler wire", WELDING PRODUCTION, vol. 33, no. 2, ABINGTON, CAMBRIDGE, G.B., pages 22 - 23 *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997040955A1 (fr) * 1996-04-29 1997-11-06 Westinghouse Electric Corporation Appareil et procede de soudage perfectionnes
FR2809039A1 (fr) * 2000-05-19 2001-11-23 Europ De Tech Torche ergonomique pour la soudure sous atmosphere de gaz inerte de type t.i.g. et son procede de montage
CN107186322A (zh) * 2017-06-29 2017-09-22 沈阳工业大学 半裂式空心钨极同轴送丝惰性气体保护焊焊枪
CN107186322B (zh) * 2017-06-29 2022-12-06 沈阳工业大学 半裂式空心钨极同轴送丝惰性气体保护焊焊枪
WO2020115033A1 (fr) * 2018-12-05 2020-06-11 Framatome Torche de soudage et procédé de fabrication correspondant
FR3089444A1 (fr) * 2018-12-05 2020-06-12 Framatome Torche de soudage et procédé de fabrication correspondant
US12330245B2 (en) 2018-12-05 2025-06-17 Framatome Welding torch and corresponding manufacturing method

Also Published As

Publication number Publication date
AU2962795A (en) 1996-02-09

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