Dual wire drive system for welding or additive manufacturing

Abstract

To provide a welding or additive manufacturing dual wire drive system.SOLUTION: A welding or additive manufacturing wire drive system includes a welding wire spool and first and second drive rolls. One or both of the drive rolls has a circumferential groove. The system includes a first welding wire drawn from the welding wire spool and located between the two drive rolls in the circumferential groove, and a second welding wire drawn from the welding wire spool and located between the two drive rolls in the circumferential groove. The first welding wire contacts the second welding wire between the first drive roll and the second drive roll. The first welding wire further contacts a first sidewall portion of the circumferential groove, and the second welding wire further contacts a second sidewall portion of the circumferential groove. Both of the first welding wire and the second welding wire are radially offset from a central portion of the circumferential groove.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of U.S. Patent Application No. 16 / 159,805, filed October 15, 2018, the disclosure of which is incorporated herein by reference.

[0002] The apparatus, system, and method according to the present invention relate to material deposition in a dual wire configuration. [Background technology]

[0003] When welding, it is often desirable to increase the width of the weld bead or the length of the weld pool during welding. This desirability can occur for a variety of reasons, which are well known in the welding industry. For example, it may be desirable to lengthen the weld pool to maintain the weld and filler metal weld pool for a longer period of time and reduce porosity. That is, a longer molten weld pool allows more time for harmful gases to escape from the weld bead before the bead solidifies. Additionally, it may be desirable to increase the width of the weld bead to cover a wider weld gap or to increase the wire deposition rate. In either case, it is common to use a larger electrode diameter. Increasing the diameter results in a longer and wider weld pool, even if it may be desirable to increase only the width or length of the weld pool, rather than both. However, this does not come without drawbacks. Specifically, because a larger electrode is used, more energy is required in the welding arc to produce a proper weld. This increased energy causes a greater heat input to the weld, which results in more energy being used in the welding operation due to the larger diameter electrode used. Furthermore, the resulting weld bead profile or cross section may not be ideal for certain mechanical applications. Rather than increasing the diameter of the electrode, it may be desirable to use two smaller electrodes simultaneously. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 5,816,466 [Patent Document 2] U.S. Patent No. 8,569,653 Summary of the Invention [Means for solving the problem]

[0005] The following summary presents a simplified overview to provide a basic understanding of some aspects of the devices, systems, and / or methods disclosed herein. This summary is not an extensive overview of the devices, systems, and / or methods disclosed herein. It is not intended to identify essential elements or to delineate the scope of such devices, systems, and / or methods. Its sole purpose is to present some aspects in a simplified form as a prelude to the more detailed description that is presented later.

[0006] According to one aspect of the present invention, a wire drive system for welding or additive manufacturing is provided. The system includes a welding wire spool, a first drive roll, and a second drive roll. One or both of the first and second drive rolls have a circumferential groove. The system includes a first welding wire unwound from the welding wire spool and disposed in the circumferential groove between the first and second drive rolls, and a second welding wire unwound from the welding wire spool and disposed in the circumferential groove between the first and second drive rolls. The first welding wire contacts the second welding wire between the first and second drive rolls. The first welding wire further contacts a first sidewall portion of the circumferential groove, and the second welding wire further contacts a second sidewall portion of the circumferential groove. Both the first welding wire and the second welding wire are radially offset from a central portion of the circumferential groove.

[0007] According to another aspect of the present invention, a wire drive system for welding or additive manufacturing is provided. The system includes a welding wire spool including a first welding wire wound on the welding wire spool and a second welding wire wound on the welding wire spool. The first drive roll has a first circumferential groove including a first inner sidewall, a first outer sidewall, and a first recessed groove bottom extending between the first inner sidewall and the first outer sidewall. The second drive roll has a second circumferential groove including a second inner sidewall, a second outer sidewall, and a second recessed groove bottom extending between the second inner sidewall and the second outer sidewall. The second circumferential groove is aligned with the first circumferential groove. The first welding wire and the second welding wire are drawn from the welding wire spool between the first drive roll and the second drive roll through both the first circumferential groove and the second circumferential groove. The biasing member biases the first drive roll toward the second drive roll to force the first welding wire into contact with the second welding wire. The first welding wire contacts each of the first inner sidewall, the second inner sidewall, and the second welding wire. The second welding wire contacts each of the first outer sidewall, the second outer sidewall, and the first welding wire. The first welding wire and the second welding wire are offset from both the first recessed groove bottom and the second recessed groove bottom.

[0008] According to another aspect of the present invention, a wire drive system for welding or additive manufacturing is provided. The system includes a welding wire spool, a first drive roll having a first annular groove, and a second drive roll having a second annular groove aligned with the first annular groove. A first welding wire is unwound from the welding wire spool and disposed in both the first and second annular grooves between the first and second drive rolls. A second welding wire is unwound from the welding wire spool and disposed in both the first and second annular grooves between the first and second drive rolls. A biasing member biases the first drive roll toward the second drive roll, causing the first welding wire to contact the second welding wire. The first welding wire contacts each of a first sidewall portion of the first annular groove, a first sidewall portion of the second annular groove, and the second welding wire. The second welding wire contacts the second sidewall portion of the first annular groove, the second sidewall portion of the second annular groove, and the first welding wire. The first drive roll and the second drive roll rotate in opposite directions, thereby unwinding the first welding wire and the second welding wire from the welding wire spool.

[0009] These and other aspects of the present invention will become apparent to those skilled in the art to which the present invention pertains from a reading of the following description taken in conjunction with the accompanying drawings, as identified below. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of an exemplary welding system. [Figure 2] FIG. 1 is a perspective view of an exemplary welding system. [Figure 3] FIG. 1 is a perspective view of an exemplary welding system. [Figure 4] FIG. 1 is a perspective view of an exemplary welding wire spool. [Figure 5] FIG. 1 is a perspective view of an exemplary welding wire spool. [Figure 6] FIG. 1 is a perspective view of an exemplary welding wire spool. [Figure 7]FIG. 1 is a side view of an exemplary wire feeder. [Figure 8] 1 illustrates an exemplary drive roll. [Figure 9] FIG. 2 is a perspective view of an exemplary drive roll. [Figure 10] 1 shows a cross-sectional view of a drive roll feeding a double wire. [Figure 11] 1 shows a cross-sectional view of a drive roll feeding a double wire. [Figure 12] 1 shows a cross-sectional view of a drive roll feeding a double wire. [Figure 13] 1 shows a cross-sectional view of a drive roll feeding a double wire. [Figure 14] 1 shows a cross-sectional view of a drive roll feeding a double wire. [Figure 15] 1 shows a cross-sectional view of a drive roll feeding a double wire. [Figure 16] 1 shows a cross-sectional view of a drive roll feeding a double wire. DETAILED DESCRIPTION OF THE INVENTION

[0011]

[0013] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings. The exemplary embodiments described are intended to aid in understanding the invention and are not intended to limit the scope of the invention in any way. Like reference numerals refer to like elements throughout.

[0012] Embodiments of the present invention are described herein with reference to welding systems. Exemplary welding systems include gas metal arc welding (GMAW) systems, submerged arc welding (SAW) systems, flux-cored arc welding (FCAW) systems, metal-cored arc welding (MCAW) systems, and the like. Additionally, while the electrodes described herein may be solid electrodes, embodiments of the present invention are not limited to the use of solid electrodes. For example, flux-cored electrodes and metal-cored electrodes may also be used without departing from the spirit or scope of the present invention. Additionally, embodiments of the present invention may also be used in manual, semi-automated, and robotic welding operations. Because such systems are well known, they will not be described in detail herein.

[0013] Embodiments of the present invention are described with respect to welding systems, however, in addition to welding operations, embodiments can also be used in additive manufacturing processes and other welding-type processes involving a driven wire electrode (e.g., hardfacing).

[0014] Referring now to the drawings, FIG. 1 illustrates an exemplary embodiment of a welding system 100. The welding system 100 includes a welding power source, or power supply 109, coupled to both a welding torch 111 and a wire feeder 105. The power supply 109 can be any known type of welding power source capable of supplying welding current and welding waveforms, such as pulse spray, STT, and / or short-arc welding waveforms. The construction, design, and operation of such power supplies are well known and need not be described in detail herein. It should also be noted that welding power can be supplied simultaneously from multiple power sources; the operation of such systems is also known. The power supply 109 can include a controller 120, which is coupled to a user interface through which a user can input control or welding parameters for the welding operation. The controller 120 can include a processor, CPU, memory, etc., which are used to control the operation of the welding process and the generation of the welding waveform. The torch 111 can be configured similarly to known manual, semi-automatic, or robotic welding torches and can be linear or gooseneck. Wire feeder 105 withdraws wire electrodes E1 and E2, respectively, from electrode sources 101 and 103, which can be of any known type, such as reels, spools, containers, or the like. Wire feeder 105 withdraws electrodes or welding wires E1 and E2 using drive rolls 107, which push or pull the electrodes toward torch 111. Details of drive roll 107 are described further below. Drive roll 107 and wire feeder 105 are configured for a double welding operation; that is, they simultaneously feed both electrodes E1 and E2 into torch 111 to strike an arc and weld workpiece W. As shown, wire feeder 105 is operatively connected to a power source 109 according to known configurations for welding operations.

[0015] When driven by drive roll 107, electrodes E1 and E2 can pass through liner 113 to deliver electrodes E1 and E2 to torch 111. Liner 113 is approximately sized to allow electrodes E1 and E2 to pass into torch 111. For example, for two electrodes with a diameter of approximately 0.030 inches, a standard 0.0625 inch diameter liner 113 (which is typically used for a single 0.0625 inch diameter electrode) can be used without modification.

[0016] In certain embodiments, the wire electrodes E1 and E2 can have different diameters. That is, embodiments of the present invention can use a first, larger-diameter electrode and a second, smaller-diameter electrode. In such embodiments, it may be possible to more conveniently weld two workpieces of different thicknesses. For example, a larger-diameter electrode can be used for a larger workpiece, and a smaller-diameter electrode can be used for a smaller workpiece. Furthermore, embodiments of the present invention can be used for many different types of welding operations, including, but not limited to, GMAW, SAW, FCAW, and MCAW. Additionally, embodiments of the present invention can be used with different types of electrodes. For example, it is contemplated that a cored electrode (e.g., flux-cored or metal-cored) can be coupled to a coreless or solid electrode. Furthermore, electrodes of different compositions can be used to achieve desired weld characteristics and composition of the final weld bead. Two different but compatible consumables can be combined to create a desired weld joint. For example, compatible consumables, such as hardfacing wire, stainless steel wire, nickel alloy, and steel wire of different compositions, can be combined. As one specific example, mild steel wire can be combined with overalloyed wire to create a 309 stainless steel composition. This can be advantageous when one consumable of a desired type does not have the desired welding characteristics. For example, some consumables for specialty welding provide the desired welding chemistry but are extremely difficult to use and produce satisfactory welds. However, embodiments of the present invention allow for the use of a combination of two consumables that are easier to weld and can create the desired welding chemistry. Embodiments of the present invention can be used to create alloy / weld deposit chemistries that would otherwise be commercially unavailable or would otherwise be prohibitively expensive to manufacture. Therefore, using two different consumables can eliminate the need for expensive or unavailable consumables. Furthermore, embodiments can be used to create dilution alloys. For example, a first welding wire can be a common, inexpensive alloy and a second welding wire can be a specialty wire.The resulting weld deposit is an average of the two wire types, intermixing well during the formation of the molten droplets, and the average cost of the two wire types is less than that of expensive specialty wires. Furthermore, in some applications, the desired weld deposit may not be available due to lack of suitable consumable chemistry, but can be achieved by mixing two standard alloy wires, which intermix in the molten droplets and are deposited as a single droplet. Furthermore, in some applications, such as the deposition of wear-resistant metals, the desired weld deposit may be a combination of tungsten carbide particles from one wire and chromium carbide particles from another wire. In other applications, a larger diameter wire containing larger particles is mixed with a smaller diameter wire containing fewer or smaller particles to deposit a mixture of the two wires, with the expected contribution from each wire being proportional to the wire size. Furthermore, while exemplary embodiments using two wire electrodes simultaneously are described herein, other embodiments of the present invention may utilize more than two electrodes. For example, it is contemplated that three or more electrode configurations may be utilized in accordance with the illustrations and descriptions provided herein.

[0017] 2 provides a perspective view of welding system 100. Wire feeder 105 includes drive rolls for transporting wire electrodes E1, E2 from electrode sources 101, 103 for use in a particular application. Wire electrodes E1, E2 may be continuously unwound from a reel, spool, or container (e.g., a box or drum) and delivered to workpiece W, which in this embodiment is a weldment. Wire feeder 105 may include a drive assembly that utilizes power from one or more propulsion devices, such as electric motors, to drive wire electrodes E1, E2 to a point of use, or to workpiece W.

[0018] The welding power supply 109 may receive electrical input power from an external power source (e.g., a commercially available power source), which is directed to an on-board transformer and processor-controlled inverter or chopper circuit (not shown). Output from the power supply 109 may be provided through a welding output terminal 121 or a stud on the welding power supply. A welding gun or torch 111 and wire conduit may be electrically connected to the welding power supply 109 through a welding wire feeder 105 to deliver welding current to the workpiece W in a manner known in the art. Welding wires E1, E2 are fed through the torch 111 and metered out, or dispensed, in any manner suitable for performing the welding process, depending on the application and / or end user. Note that the electrodes E1, E2 conduct the electricity to establish the welding arc; they have a voltage potential at or near the same as the output voltage of the welding power supply 109, which may be substantially higher than ground, and are delivered to the workpiece W.

[0019] Different modes of transport of the wire electrodes E1, E2 are known in the art, one example of which includes pushing the electrodes through power or torque provided by a thruster. Other modes of electrode transport include a push / pull mode utilizing multiple thrusters. The electrodes E1, E2 are delivered to the torch 111, which may have a trigger or other activation mechanism to eject the electrodes at the user's discretion. At times, it may be necessary to deliver the electrodes E1, E2 at different feed rates. Therefore, the thruster has an adjustable output to vary the wire feed speed (WFS) of the electrodes E1, E2. In particular, the drive motor of the wire feeder 105 may be a variable speed motor to adjust the WFS.

[0020] Drive motor 123 is shown in Figure 7. Wire feeder 105 and / or drive motor 123 may draw operating power from welding power source 109, or both from separate power sources. Furthermore, any method of providing power to operate welding wire feeder 105 and / or drive motor 123 may be selected according to sound engineering judgment as suitable for use with embodiments of the present invention.

[0021] 2 and 7, welding wire feeder 105 may include a drive assembly, or drive roll assembly. As previously mentioned, drive motor 123, also referred to as a wire feeder motor, delivers power, i.e., torque, to transport first and second welding wires E1, E2 from the wire feeder to torch 111 and then to workpiece W. Drive rolls 107 are included, which grip welding wires E1, E2 and push or pull them in the appropriate direction, i.e., toward workpiece W. Sets of drive rolls 107 are vertically aligned and have correspondingly aligned annular or circumferential grooves through which welding wires E1, E2 pass simultaneously. As can be seen, the sets of vertically aligned drive rolls 107 rotate in opposite directions to drive welding wires E1, E2 through wire feeder 105. For example, in FIG. 7, the upper drive roll 107 rotates clockwise and the lower drive roll rotates counterclockwise. The drive roll 107 may be cylindrical in configuration, or more specifically, disk-shaped, although the specific configuration should not be understood as limiting. The surface, i.e., outer circumference, of the drive roll 107 may be made of a sufficiently hard material, such as steel, that is durable and suitable for gripping the welding wires E1 and E2. As shown, the drive rolls 107 may be arranged in pairs along the wire trajectory, with each drive roll of the pair supported on opposite sides of the welding wires E1 and E2, and with each outer circumference portion of the roll engaging each side of the wire (e.g., from above and below). Note that the central axes of each drive roll 107 extend substantially parallel to one another and generally transverse to the trajectories of the welding wires E1 and E2.

[0022] The wire feeder 105 can include a biasing member that biases the set of vertically aligned drive rolls 107 toward each other. The biasing member sets the fixed or compressive force that the drive rolls 107 exert on the welding wires E1, E2. For example, the wire feeder 105 can include a biasing spring 125 that applies a biasing force to one or more drive rolls 107 to set the compressive force that the drive rolls exert on the welding wires E1, E2. In the exemplary embodiment of FIG. 7 , the biasing spring 125 is attached to an adjustment rod 127 that can move inward and outward to adjust the compressive force of the biasing spring 125. The force of the biasing spring 125 is transmitted to the upper drive roll 107 via a pivoting lever 129. As previously mentioned, the set of vertically aligned drive rolls 107 has correspondingly aligned annular or circumferential grooves through which the welding wires E1, E2 pass simultaneously. That is, the welding wires E1, E2 are positioned together in the grooves of the upper and lower drive rolls. Welding wires E1, E2 are secured or compressed within the grooves by a biasing force applied to drive roll 107 by biasing spring 125. As explained further below, welding wires E1, E2 are forced into contact with each other within the grooves when secured by drive roll 107. In addition to the upward / downward compressive forces applied to welding wires E1, E2, a lateral compressive force is also applied to welding wires E1, E2, forcing them together into the interior of the groove. The lateral compressive force is provided through the shape of the sidewalls of the groove.

[0023] Further details regarding the construction of welding wire feeders are described in U.S. Pat. No. 6,619,989, issued Oct. 6, 1998, and U.S. Pat. No. 6,619,939, issued Oct. 29, 2013, both of which are incorporated herein by reference.

[0024] FIG. 3 provides a perspective view of a welding system 100 having a single electrode source 102 (e.g., a single welding wire spool) that provides both wire electrodes E1 and E2. In FIG. 3, wire electrodes E1 and E2 are wound on the same spool 102 and simultaneously drawn therefrom by a wire feeder 105. An advantage of providing both wire electrodes E1 and E2 on a single spool 102 is that existing welding systems can be configured to perform dual-wire welding with minimal modifications. Existing welding systems typically have a single spindle for a single welding wire spool. The dual-wire spool shown in FIG. 3 can be installed in such a system. A conventional single-wire welding system can be easily converted to dual-wire welding by replacing the drive roll in the wire feeder 105 with a drive roll configured for dual-wire feeding and the contact tip of the torch 111 with a contact tip configured for dual-wire welding. As previously mentioned, electrodes E1 and E2 can have the same composition and diameter or different compositions and / or diameters.

[0025] Figure 4 shows a spool 102 without any electrodes wound on it, while Figure 5 shows a spool wound with electrodes E1 and E2. The spool 102 has a central barrel 108 disposed between end flanges 104 and 106, with both electrodes E1 and E2 wound around the central barrel between the end flanges. Figure 6 shows another exemplary spool 110, which has an annular partition means 112 disposed along the central barrel. The annular partition means is disposed between and separates the windings of electrodes E1 and E2.

[0026] 8 and 9 show an exemplary drive roll 107. The drive roll has a central bore. The inner surface of the bore may include a shaped recess 131 for receiving a protrusion on a drive mechanism, such as a drive gear, to transmit drive torque to the drive roll 107. The drive roll 107 includes one or more annular or circumferential wire-receiving grooves 133, 135. The wire-receiving grooves 133, 135 are axially spaced about the circumference of the drive roll 107. The wire-receiving grooves 133, 135 are designed to receive two welding wires. Exemplary standard welding wire diameters for use in the drive roll 107 include 0.030 inches, 0.035 inches, 0.040 inches, 0.045 inches, etc. The wire-receiving grooves 133, 135 may have the same width and depth as one another or may have different widths and depths to accommodate different sizes or combinations of dual welding wires. If each of the wire-receiving grooves 133, 135 has the same width and depth, the drive roll 107 can be reused after one groove wears out by simply flipping the drive roll over and reinstalling it on the wire feeder. The wire-receiving grooves 133, 135 can be configured to simultaneously drive two wires of the same diameter or two wires of different diameters. In FIG. 8 , the wire-receiving grooves 133, 135 have a trapezoidal shape with straight, angled, or inwardly tapering sidewalls and a flat bottom extending between the sidewalls. However, the wire-receiving grooves 133, 135 can have other shapes in addition to a trapezoidal shape, such as a curved or recessed groove bottom. In certain embodiments, the grooves 133, 135 can include knurling or other frictional surface treatments to aid in gripping the welding wire.

[0027] 10-16 show partial cross-sectional views of an exemplary drive roll 107 when mounted on a wire feeder to feed dual welding wires. The drive rolls 107 are biased toward one another to provide a clamping force to the first welding wire E1 and the second welding wire E2. Both welding wires E1 and E2 are disposed within annular grooves in the upper and lower drive rolls 107. The annular grooves are aligned and may have a trapezoidal shape. In FIG. 10, the trapezoidal shape is an isosceles trapezoid formed by an inner sidewall 137, an outer sidewall 139, and a groove bottom 141 extending between the sidewalls. The isosceles trapezoidal shape is inverted so that the cross-section is recessed from the outer circumferential surface of the drive roll 107.

[0028] The biasing force applied by the drive roll 107 secures the welding wires E1 and E2 within the annular groove between the upper and lower groove sidewalls 137 and 139 and the adjacent welding wire. The welding wires E1 and E2 are held stable within the annular groove through three contact points. This securement system allows both wires to feed through the wire feeder in a consistent manner. The two welding wires E1 and E2 support each other during feeding and are pulled together through friction. Because the inner and outer sidewalls 137 and 139 of the annular groove are angled, they exert both vertical and horizontal clamping forces on the welding wires E1 and E2. The horizontal clamping force pushes the welding wires E1 and E2 together, thereby contacting each other. In certain embodiments, the welding wires E1 and E2 are secured within the annular groove and radially offset from the surface of the groove bottom 141. That is, the welding wires E1, E2 are secured between each other and between the angled side walls 137, 139 of the groove, with a gap between the welding wires and the groove bottom 141. This can be seen clearly in FIG.

[0029] The above-described clamping system can accommodate some variation in the diameter of the welding wires E1, E2 (e.g., due to manufacturing tolerances). Each welding wire E1, E2 has its own annular groove in the drive roll 107. If one welding wire E1, E2 is slightly larger than the other, the smaller welding wire may not be adequately clamped between the drive rolls. In such a case, the larger diameter welding wire limits the radial displacement of the drive rolls 107 toward each other, thereby preventing proper clamping of the smaller diameter welding wire. This leads to feeding problems and the so-called entanglement of the smaller diameter welding wire during feeding. The above-described clamping system can accommodate wires of different sizes because the clamping system is self-adjusting. As can be seen in FIG. 11 , if one welding wire E2 is larger than the other wire E1, the contact point between the wires is axially shifted from the center of the annular groove toward the smaller diameter wire. The three contact points are maintained on each welding wire E1, E2 by the groove sidewalls 137, 139 and the adjacent welding wire.

[0030] FIG. 12 shows a drive roll 107 having an annular groove 143 whose cross section has the shape of a trapezoid with an acute angle instead of an isosceles trapezoid. The inner sidewall 145 and outer sidewall 147 of the groove have different lengths and form different angles with the outer circumferential surface of the drive roll. In FIG. 13, the drive roll 107 has an annular groove 149 having a trapezoid shape that includes a right angle. A trapezoidal groove with acute and right angles can accommodate a larger difference in welding wire diameter than an isosceles trapezoid. Therefore, a trapezoidal groove with acute angles and diameters can be used to drive welding wires with different diameters, for example, 0.040 inch welding wire and 0.045 inch welding wire. In certain embodiments, the sidewalls and / or bottom of the groove can be curved (e.g., concave or convex). Additionally, the transition at the inner corner between the sidewall and bottom of the trapezoidal groove can be curved or radiused. 14 shows an exemplary drive roll having annular grooves with straight, beveled sides 150 joined by concave, curved, or radiused groove bottoms 152. In an exemplary embodiment, the angle between the sidewalls 150 and the outer circumference of the drive roll 107 is approximately 150°, although other angles are possible and can be determined with sound engineering judgment.

[0031] FIG. 15 illustrates an exemplary embodiment in which one drive roll 107 has trapezoidal grooves for welding wires E1 and E2, and the other drive roll 107a has non-trapezoidal grooves. In FIG. 15, the non-trapezoidal grooves are rectangular, but other shapes are possible. For example, the non-trapezoidal grooves can be curved, such as oval or circular. Furthermore, the trapezoidal grooves are shown disposed on the lower drive roll 107. However, trapezoidal grooves could be disposed on the upper drive roll 107a, and non-trapezoidal grooves could be disposed on the lower drive roll. The welding wires E1 and E2 are secured between the respective side walls 137 and 139 of the trapezoidal grooves and the bottom 153 of the non-trapezoidal groove 151, and the welding wires are brought into contact with each other as described above. Therefore, the welding wires E1 and E2 are stably held within the drive rolls 107 and 107a through three contact points.

[0032] 16 illustrates an exemplary embodiment in which one drive roll 107 has trapezoidal grooves for welding wires E1, E2, while the other drive roll 107b has no grooves and directly contacts the welding wires on its outer circumferential surface 155. The trapezoidal grooves are shown disposed on the lower drive roll 107. However, trapezoidal grooves can also be disposed on the upper drive roll. The welding wires E1, E2 are secured between the respective side walls 137, 139 of the trapezoidal grooves and the outer circumferential surface 155 of the upper drive roll 107b, and the welding wires are brought into contact with each other as described above. Therefore, the welding wires E1, E2 are stably held through three contact points.

[0033] It should be apparent that the present disclosure is an example and that various modifications may be made by adding, modifying, or eliminating details without departing from the fair scope of the teachings contained herein. Accordingly, the invention is not limited to the particular details of this disclosure except to the extent that the following claims necessarily so limit the invention. [Explanation of symbols]

[0034] 100 Welding System 102 spool 104 End flange 105 Wire Feeder 106 End flange 107 Drive Roll 107a Upper drive roll 108 Center Barrel 109 Power supply 110 spool 111 Torch 112 Annular partition means 125 bias spring 127 Adjustment Rod 131 Molded recess 133 Wire receiving groove 135 Wire receiving groove 137 Inner sidewall of groove 139 Outer sidewall of groove 141 Groove bottom 145 Inner sidewall of groove 147 Outer sidewall of groove 150 side wall 151 Groove 152 Curved or R-shaped groove bottom 153 Bottom E1, E2 welding wire W Workpiece

Claims

1. a welding wire spool; a first drive roll; a second drive roll, wherein one or both of the first drive roll and the second drive roll have a circumferential groove; a first welding wire drawn from the welding wire spool and disposed in the circumferential groove between the first drive roll and the second drive roll; a second welding wire drawn from the welding wire spool and disposed in the circumferential groove between the first drive roll and the second drive roll; A wire drive system for welding or additive manufacturing, comprising: the first welding wire contacts the second welding wire between the first drive roll and the second drive roll, the first welding wire further contacts a first sidewall portion of the circumferential groove, and the second welding wire further contacts a second sidewall portion of the circumferential groove; the circumferential groove includes a groove bottom between a first sidewall portion and a second sidewall portion, and both the first welding wire and the second welding wire are radially offset from the groove bottom of the circumferential groove. Wire drive systems for welding or additive manufacturing.

2. 10. The wire drive system for welding or additive manufacturing of claim 1, wherein the first welding wire and the second welding wire have different diameters.

3. 10. The wire drive system for welding or additive manufacturing of claim 1, wherein the first welding wire and the second welding wire have different compositions.

4. 10. The wire drive system for welding or additive manufacturing of claim 1, wherein the first welding wire is a solid welding wire and the second welding wire is a flux-cored welding wire.

5. 10. The wire drive system for welding or additive manufacturing of claim 1, wherein the first welding wire is a solid welding wire and the second welding wire is a metal core welding wire.

6. 2. The wire drive system for welding or additive manufacturing according to claim 1, wherein the groove bottom of the circumferential groove is concave.

7. 10. The welding or additive manufacturing wire drive system of claim 1, wherein the welding wire spool includes a central barrel disposed between first and second end flanges, and an annular partition means disposed along the central barrel between the first welding wire and the second welding wire.

8. a welding wire spool including a first welding wire wound on the welding wire spool and a second welding wire wound on the welding wire spool; a first drive roll having a first inner sidewall, a first outer sidewall, and a first circumferential groove including a first recessed groove bottom extending between the first inner sidewall and the first outer sidewall; a second drive roll having a second inner sidewall, a second outer sidewall, and a second circumferential groove including a second recessed groove bottom extending between the second inner sidewall and the second outer sidewall, the second circumferential groove being aligned with the first circumferential groove, and the first welding wire and the second welding wire being pulled from the welding wire spool between the first drive roll and the second drive roll through both the first circumferential groove and the second circumferential groove; a biasing member that biases the first drive roll toward the second drive roll to force the first welding wire into contact with the second welding wire; A wire drive system for welding or additive manufacturing, comprising: the first welding wire contacts each of the first inner sidewall, the second inner sidewall, and the second welding wire; the second welding wire contacts each of the first outer sidewall, the second outer sidewall, and the first welding wire; the first welding wire and the second welding wire are vertically offset from both the first recessed groove bottom and the second recessed groove bottom; the welding wire spool includes a central barrel disposed between a first end flange and a second end flange, and an annular partition means disposed along the central barrel between the first welding wire and the second welding wire. Wire drive systems for welding or additive manufacturing.

9. 9. The wire drive system for welding or additive manufacturing of claim 8, wherein the first welding wire and the second welding wire have different diameters.

10. 9. The wire drive system for welding or additive manufacturing of claim 8, wherein the first welding wire and the second welding wire have different compositions.

11. 9. The wire drive system for welding or additive manufacturing of claim 8, wherein one of the first welding wire and the second welding wire is a solid welding wire and the other of the first welding wire and the second welding wire is a flux-cored welding wire.

12. 9. The wire drive system for welding or additive manufacturing according to claim 8, wherein one of the first welding wire and the second welding wire is a solid welding wire, and the other of the first welding wire and the second welding wire is a metal-core welding wire.

13. a welding wire spool; a first drive roll having a first annular groove; a second drive roll having a second annular groove aligned with the first annular groove; a first welding wire drawn from the welding wire spool and disposed within both the first annular groove and the second annular groove between the first drive roll and the second drive roll; a second welding wire drawn from the welding wire spool and disposed within both the first annular groove and the second annular groove between the first drive roll and the second drive roll; a biasing member that biases the first drive roll toward the second drive roll to force the first welding wire into contact with the second welding wire; A wire drive system for welding or additive manufacturing, comprising: the first welding wire contacts each of a first sidewall portion of the first annular groove, a first sidewall portion of the second annular groove, and the second welding wire; the second welding wire contacts each of the second sidewall portion of the first annular groove, the second sidewall portion of the second annular groove, and the first welding wire; the first annular groove includes a first groove bottom between a first sidewall portion and a second sidewall portion of the first annular groove; the second annular groove includes a second groove bottom between a first sidewall portion and a second sidewall portion of the second annular groove; the first drive roll and the second drive roll rotate in opposite directions, thereby unwinding the first welding wire and the second welding wire from the welding wire spool; the welding wire spool includes a central barrel disposed between a first end flange and a second end flange, and an annular partition means disposed along the central barrel between the first welding wire and the second welding wire. Wire drive systems for welding or additive manufacturing.

14. 14. The wire drive system for welding or additive manufacturing of claim 13, wherein the first welding wire and the second welding wire have different diameters.

15. 14. The wire drive system for welding or additive manufacturing of claim 13, wherein the first welding wire and the second welding wire have different compositions.

16. 14. The welding or additive manufacturing wire drive system of claim 13, wherein the first welding wire is a solid welding wire and the second welding wire is a flux-cored welding wire.

17. 14. The wire drive system for welding or additive manufacturing of claim 13, wherein the first welding wire is a solid welding wire and the second welding wire is a metal core welding wire.

18. 14. The welding or additive manufacturing wire drive system of claim 13, wherein each of the first groove bottom and the second groove bottom is concave.

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