Bimetallic welding electrode

Abstract

An electrode is disclosed for use in MIG/MAG welding. The electrode comprises an elongated electrode body within which is embedded a metallic filament. In some embodiments, the filament is copper, and is offset from the center of the electrode body. A method is disclosed for forming an electrode. The method may include removing oxidation from a surface of an electrode body, forming the electrode body to a desired size and geometry, removing lubricants from the surface of the electrode body, forming an elongated channel in a surface of the electrode body, depositing a filament in the elongated channel, and forming the electrode body over the filament. Other embodiments are disclosed and claimed.

Claims

1. A bimetallic welding wire, comprising: a welding wire having a longitudinal axis, the welding wire having an elongated channel formed on a surface thereof, the elongated channel aligned with the longitudinal axis; an arc enhancing material disposed in the elongated channel; and a metal filament disposed in the elongated channel such that the metal filament lays on top of the arc enhancing material; wherein the elongated channel is offset from a center of the welding wire.

2. The bimetallic welding wire of claim 1, wherein the welding wire comprises steel and the metal filament comprises copper.

3. The bimetallic welding wire of claim 1, wherein the arc enhancing material is selected from the list consisting of lithium, sodium, potassium, cesium rubidium, tungsten and carbon, including their forms in either a salt, compound molecule or elemental form.

4. The bimetallic welding wire of claim 1, a longitudinal axis of the elongated channel is oriented parallel to the longitudinal axis of the welding wire.

5. The bimetallic welding wire of claim 1, wherein the metal filament comprises an alloying element.

6. The bimetallic welding wire of claim 5, wherein the alloying element is selected from the list consisting of carbon, silicon, manganese, chromium, molybdenum, nickel and vanadium.

7. The bimetallic welding wire of claim 1, wherein a portion of the metal filament is exposed to the surface.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) By way of example, specific embodiments of the disclosed device will now be described, with reference to the accompanying drawings, in which:

(2) FIG. 1 is a schematic diagram of an exemplary device for MIG/MAG-welding;

(3) FIG. 2 is a schematic diagram illustrating an exemplary arrangement for making an electrode in accordance with the disclosure;

(4) FIGS. 3A-3E are cross-section views of the electrode at various points in the manufacturing process;

(5) FIG. 4 is a schematic diagram illustrating an alternative exemplary arrangement for making an electrode in accordance with the disclosure;

(6) FIG. 5 is a flow chart illustrating an exemplary method of making an electrode in accordance with the disclosure; and

(7) FIG. 6 is a flow chart illustrating an exemplary alternative method of making an electrode in accordance with the disclosure.

DETAILED DESCRIPTION

(8) FIG. 1 illustrates an exemplary arrangement of welding equipment used for MIG/MAG welding. A welding machine 10 includes a power source 1 adapted to supply welding energy, or melting power, to an electrode 7. In some cases, the power source 1 comprises an inverter power supply. An electrode feeder 2 is provided on the welding machine 10, and operates to feed the electrode 7 to a welding torch 3. The welding torch 3 is connected to the electrode feeder 2, the welding machine 10 and a gas container 4 via a welding cable. The welding torch 3 comprises a gas cup 5 and a contact tube 6 through which the electrode 7 is fed to a position in the proximity of the workpiece 8. Welding gas is supplied from the gas container 4 to the space enclosed between the gas cup 5 and the contact tube 6. The welding equipment may also comprise a welding controller 20. The welding controller 20 includes a general controller 21 which is arranged to control the welding current and voltage by setting appropriate static and dynamic characteristics for a work piece to be welded. The general controller 21 can also be configured to regulate the feeding velocity of the electrode feeder 2. The general controller 21 specifically sets a reference voltage which is used as a reference for an average voltage during the welding process.

(9) Referring to FIGS. 2 and 3A-3E, an exemplary process is illustrated for making electrodes for use with the welding machine 1 of FIG. 1. It will be appreciated that the disclosed electrodes are not limited to use with the welding machine of FIG. 1, but instead can be used with any of a variety of appropriate welding equipment.

(10) FIG. 2 shows an exemplary process for converting a length of stock welding wire 22 into a bimetallic welding electrode having enhanced performance characteristics in accordance with the present disclosure. The stock wire 22 may be any variety of conventional materials used for MIG/MAG welding, such as steel, aluminum, stainless steel, or various composite materials, and may conform to any desired electrode specification (e.g., S2, S3, S6, etc.). As will be appreciated by those of ordinary skill in the art, the stock wire may be alloyed with additional metals to improve certain attributes of the resulting, such as arc stability, feeding resistance, and susceptibility to surface oxidation.

(11) Referring to FIGS. 2 and 3A-3E, a first embodiment of the disclosed technique for manufacturing a MIG/MAG electrode will be described. A stock wire 22 may be introduced into a reduction or shaping die 24 along the direction of arrow A. The reduction or shaping die 24 may be configured to provide the wire with a consistent, circular cross section. The wire 22 is then introduced between first and second rollers 26, 28, at least one of which is provided with a surface feature 30 configured to impart a longitudinally-extending channel 32 to the surface of the wire 22. In the illustrated embodiment, the pair of rollers 26, 28 are disposed in an opposing, laterally-spaced relationship, and the first rollers 26 includes a circumferential projection 30 extending radially therefrom so that as the wire 22 is fed through the rollers 26, 28, the projection 30 is forcibly pressed into the surface of the wire 22, thus forming the longitudinally-extending channel 32. The channel 32 is shown in FIG. 3A as having a substantially rounded, U-shaped cross-section. It will be appreciated, however, that the channel 32 may be provided in any of a variety of different cross sectional shapes, such as rectangular, V-shaped or the like. In addition, the dimensions of the channel 32 may be selected to accommodate the particular size and shape of the material being deposited therein, and to ensure that at least a portion of the filament is exposed to the surface of the resulting electrode. The shape and size of the channel 32 may be controlled through selection of the projection 30 used to form the channel 32.

(12) In some embodiments, one or more arc enhancing materials 34 may be deposited in the channel 32. The arc enhancing materials may provide the finished electrode with desired arc start and stability characteristics. Examples of arc enhancing materials 34 include lithium, sodium, potassium, cesium rubidium, tungsten, carbon and the like including their forms in either a salt, compound molecule or elemental form. Such materials 34 may be applied to an interior surface of the channel 32. Nominal % of these material can range from 1 g per kilogram to 100 g per kilogram depending on the element and the welding application. If arc enhancing materials 34 are used, the channel 32 may be sized accordingly.

(13) A current conducting filament 36 may be disposed in the channel 32 so that it lays on top of the arc enhancing material 34 (where such materials are used). The arrangement of the wire 22, arc enhancing materials 34 and filament 36 is shown in cross-section in FIGS. 3B and 3C. The filament 36 may be drawn from a spool 38 in a continuous fashion and laid into the channel 32 as the wire 22 is moved in the direction of arrow A. In some embodiments, the filament 36 may comprise copper so as to provide the resulting bare electrode with all of beneficial characteristics of copper coated electrodes. The filament 36 may have a diameter that results in a desired weight percent of copper in relation to the base metal in the wire 22, such as may be required by the particular application. In one non-limiting exemplary embodiment, the filament is sized so that the resulting electrode includes 0.12% copper, which may correspond to a filament having a diameter of 0.012inches. In other embodiments, the filament 36 may be sized so that resulting electrode includes 0.5% copper, such that a correspondingly larger filament may be used. The channel 32 may be sized appropriately to fit within the filament 36 in a closely conforming relationship therewith. Although the filament 36 is shown as being circular in cross-section, it will be appreciated that it can instead be provided in other shapes, such as flat (strip), rectangular, triangular, and the like.

(14) The wire 22, with the filament 36 and optionally the arc enhancing materials 34, may then be passed through a pair of rollers 40, 42 disposed in an opposing, laterally-spaced relationship. The rollers 26 and 28 may compress the wire, forcing the walls of the channel 32 inward, and forming the wire material over the filament so as to partially or completely enclose the filament 36 within the wire 22. The cross-section at this stage is shown in FIG. 3D. If arc enhancing materials 22 are used, they will be sealed within the wire 22 along with the filament. Nominally the base material will interface with the filament to join the filament to the base material. The filament may be joined to the base material via various methods to ensure it is held in place in the base material.

(15) Preferably, the filament material will be placed into the base material in a manner that ensures that a portion of the filament is exposed to the surface. The wire 22, including the filament 36 and the arc enhancing materials (if used) may then be introduced into a reduction die 44 to reduce the diameter of the wire 22 to a desired final size and outer contour is provided. The cross-section at this stage is shown in FIG. 3E. The finished electrode 46 may be cut to a desired length and packaged, or may be passed along for further processing.

(16) As can be seen, the filament 36 (along with any arc enhancing materials) are offset from the longitudinal axis A of the finished electrode 46 by an offset distance O, so that the filament lies directly adjacent to the electrode's outer surface 47 and a portion of the filament is exposed to the outer surface 47. The copper present on the electrode 46 wire will effectively serve as a sacrificial material to stabilize the arc erosion process between the tip and the electrode.

(17) As previously noted, applying a copper or other current transferring filament to the wire 22 in the manner described above provides several advantages relative to conventional copper plating techniques. The above-described process does not require specialized electroplating equipment or facilities and may therefore be performed on-site and on an as-needed basis by a retailer or other non-manufacturer party. Moreover, the process of the present disclosure does not require the use of acids, caustic agents, or copper sulfate (CuSO.sub.4), and does not produce contaminated waste water or fumes that can be harmful to the environment.

(18) Referring now to FIG. 4, an embodiment will be described in which alloying materials may be introduced into a wire in a manner similar to that described in relation to FIG. 2. As will be appreciated, by providing alloying materials within a channel in a generic wire, cost savings can be achieved by eliminating the need to stock a large number of different wires having different alloy compositions. Rather, a large volume of a relative small number of different wire base materials can be stocked, and when an order is received, a desired alloy formulation may be added to the base material in an efficient and tightly controllable manner. In one embodiment the base material of the stock wire 48 is steel. It will be appreciated, however, that the invention is not so limited, and other base materials can also be used, as desired. The disclosed technique may facilitate the manufacture of most desired alloyed grades starting from the same non-alloyed base wire material.

(19) The stock wire 48 may be introduced into a reduction or shaping die 50 along the direction of arrow A. The reduction or shaping die 50 may be configured to provide the wire with a consistent, circular cross section. The wire 48 is then introduced between first and second rollers 52, 54, at least one of which is provided with a surface feature 56 configured to impart a longitudinally-extending channel 58 to the surface of the wire 48. In one embodiment, the surface feature 56 is a circumferential projection extending radially therefrom so that as the wire 48 is fed through the rollers 52, 54, the projection is forcibly pressed into the surface of the wire 48, thus forming the longitudinally-extending channel 58. The channel 58 may have some or all of the characteristics described in relation to the channel 32 of FIGS. 2-3E.

(20) In some embodiments, one or more alloying materials 60 may be disposed in the channel 58. These alloying materials 60 may be formulated so that a finished weld will have a desired material composition. Examples of appropriate alloying materials include Aluminum, Arsenic, Boron, Carbon, Calcium, Chromium, Copper, Hydrogen, Mangenese, Molybdenum, Nitrogen, neodymium, Nickle, Oxygen, Antimony, Silicon, Tin, Titanium, Tungsten, Zirconium and the like in elemental, salt or compound format. In the illustrated embodiment, the alloying material 60 is provided in the form of a strip which is laid into the channel 58. Although not shown, in some embodiments, are enhancing materials, similar to those described in relation to FIGS. 2-3E may be disposed in the channel 58 so that the alloying material 60 is laid on top thereof. The alloying material 60 may be drawn from a spool 62 in a continuous fashion and laid into the channel 58 as the wire 48 is moved in the direction of arrow A. When provided in strip form, the alloying material 60 may have a diameter that results in a desired material composition of the resulting weld. The channel 58 may be sized appropriately to fit around the alloying material 60 in a closely conforming relationship therewith. The alloying material 60, when provided in strip form, may have a cross-section that is circular, flat (strip), rectangular, triangular, and the like.

(21) The wire 48, with the alloying material 60 and optionally the arc enhancing materials, may then be passed through a pair of rollers 64, 66 disposed in an opposing, laterally-spaced relationship. The rollers 64, 66 may compress the wire 48, forcing the walls of the channel 58 inward, and forming the wire material over the alloying material so as to partially or completely enclose the alloying material within the wire 48. If arc enhancing materials are used, they will be sealed within the wire 48 along with the alloying material.

(22) The wire 48, including the alloying material 60 and the arc enhancing materials (if used) may then be introduced into a reduction die 68 to reduce the diameter of the wire 48 to a desired final size and outer contour is provided. The finished electrode 70 may be cut to a desired length and packaged, or may be passed along for further processing.

(23) As with the previously described embodiment, the additives (the alloying material and any arc enhancing materials) are offset from the longitudinal axis of the wire, at or beneath the wire's surface. During welding, the alloying materials will combined with the base wire material to result in a weld having desired alloy properties.

(24) It will be appreciated that the alloying material can also be used in combination with a metal filament. In addition, in some embodiments, a metal filament may be used in combination with arc enhancing materials and alloying materials.

(25) Referring now to FIG. 5, an exemplary method of making an electrode will be described. At step 100, surface oxidation may be removed from a stock wire using one or more chemical and/or mechanical processes. At step 110, the wire may be drawn down slightly to provide a desired consistent outer shape. At step 120, a surface treatment may be performed to remove forming lubricants from the surface of the wire. At step 130, a longitudinally-extending channel may be formed in the wire using a roll forming process. In one embodiment, the wire is fed between a pair of rollers disposed in an opposing, laterally-spaced apart relationship. One the rollers may include a circumferential projection so that as the wire is fed between the rollers the projection is forcibly pressed into the surface of the wire, thus forming the channel therein. At optional step 140, one or more arc enhancing elements or compounds may be deposited in the channel. At step 150, a metal filament is disposed in the channel. The filament may be formed of copper, for example, for providing the electrode with beneficial characteristics that have heretofore been realized by providing electrodes with a copper coating using conventional copper plating processes. At step 160, the wire and filament may be mechanically compressed by a die or roll forming process. In one embodiment, the wire (with the embedded filament) may be fed between a pair of pinch rollers so that the filament is forcibly pressed into the channel and the walls of the channel are forced inward to partially or completely enclose the filament. At step 170, the wire, including the filament and any additional optional arc enhancing materials, may be drawn through a reduction die to reduce the diameter of the wire to a desired final size and to ensure concentric geometry. The resulting finished electrode may be cut to a desired length and packaged, or may be passed along for further processing.

(26) FIG. 6 shows an exemplary alternative method according to the disclosure. At step 200, surface oxidation may be removed from a stock wire using one or more chemical and/or mechanical processes. At step 210, the wire may be drawn down slightly to provide a desired consistent outer shape. At step 220, a surface treatment may be performed to remove forming lubricants from the surface of the wire. At step 230, a longitudinally-extending channel may be formed in the wire using a roll forming process. In one embodiment, the wire is fed between a pair of rollers disposed in an opposing, laterally-spaced apart relationship. One the rollers may include a circumferential projection so that as the wire is fed between the rollers the projection is forcibly pressed into the surface of the wire, thus forming the channel therein. At optional step 240, one or more arc enhancing elements or compounds may be deposited in the channel. At step 250, an alloying element is disposed in the channel. The alloying element may be formed of Chromium, for example, for providing the ultimate weld metal with a desired alloy composition. At step 260, the wire and alloying element may be mechanically compressed by a die or roll forming process. In one embodiment, the wire (with the embedded alloying element) may be fed between a pair of pinch rollers so that the alloying element is forcibly pressed into the channel and the walls of the channel are forced inward to partially or completely enclose the alloying element. At step 270, the wire, including the alloying element and any additional optional arc enhancing materials, may be drawn through a reduction die to reduce the diameter of the wire to a desired final size and to ensure concentric geometry. The resulting finished electrode may be cut to a desired length and packaged, or may be passed along for further processing.

(27) As used herein, an element or step recited in the singular and proceeded with the word a or an should be understood as not excluding plural elements or steps, unless such exclusion is explicitly recited. Furthermore, references to one embodiment of the present invention are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

(28) While certain embodiments of the disclosure have been described herein, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.