Systems and methods for using multiphase arc preheating for wire surface oxidation removal and / or wire preheating

Abstract

Disclosed is an apparatus and system for preheating a welding wire and removing surface oxidation of the welding wire using an electric arc via three or more tungsten electrodes connected to a polyphase preheating power source. Arc preheating of the welding wire allows for increased efficiency and deposition rate.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62 / 892,116, filed on Aug. 27, 2019, entitled “Systems and Methods for Wire Surface Oxidation Removal And / Or Wire Preheating Using Polyphase Electric Arc Preheating”. The entire content of U.S. Provisional Patent Application Ser. No. 62 / 892,116 is hereby expressly incorporated by reference. Background Art

[0003] The present disclosure relates to welding systems, and more particularly to systems and methods for wire surface oxidation removal and / or wire preheating using a tungsten - electrode arc.

[0004] Welding is a process that is becoming increasingly common in all industries. A wide variety of welding systems and welding control schemes have been implemented for various purposes. In continuous welding operations, gas metal arc welding (GMAW) and submerged arc welding (SAW) techniques allow for the formation of continuous weld beads by feeding a wire shielded by an inert gas from a torch. Such wire - feeding systems are available for other welding systems, such as tungsten inert gas (TIG) welding. Electric power is applied to the wire and the circuit is completed through the workpiece to maintain the welding arc, which melts the electrode wire and the workpiece to form the desired weld. Summary of the Invention

[0005] The present disclosure relates to welding systems, and more particularly to systems and methods for wire surface oxidation removal and / or wire preheating using an arc, substantially as shown by and described in conjunction with at least one figure, and more thoroughly set forth in the present disclosure. Brief Description of the Drawings

[0006] Figure 1a is an illustration of an exemplary welding - type system in accordance with aspects of the present disclosure.

[0007] Figure 1b is a block diagram of an exemplary welding - type system in accordance with aspects of the present disclosure.

[0008] Figure 2a is an illustration of an isometric view of a torch configured to preheat a wire via arc preheating.

[0009] Figure 2b isFigure 2a Illustration of a cross-sectional view of a torch configured to preheat a wire via arc preheating.

[0010] Figure 3a Is a block diagram of an exemplary arc preheating system, showing the current path of the exemplary arc preheating system.

[0011] Figure 3b Is that can be applied to Figure 3a Exemplary time curve diagrams of the voltages of the phases of the three-phase power that can be applied to the arc preheating system.

[0012] Figure 4a Illustration of an exemplary arrangement of an arc preheating system using three tungsten electrodes.

[0013] Figure 4b Is Figure 4a Side view of an exemplary arc preheating system including three tungsten electrodes of

[0014] Figure 5a Illustration of an exemplary arrangement of an arc preheating system using four tungsten electrodes.

[0015] Figure 5b Is Figure 5a Side view of an exemplary arc preheating system including four tungsten electrodes of

[0016] The drawings are not necessarily to scale. Where appropriate, like or identical reference numerals are used to refer to like or identical parts. Detailed Description

[0017] In some welding applications, it is desirable to preheat the wire before depositing it onto the workpiece. Preheating the wire can provide one or more advantages, such as reducing the heat applied to the workpiece via the welding arc, increasing the deposition rate, and / or reducing the hydrogen present in the weldment. For example, in a system where the wire is not preheated, the power from the welding arc must be sufficient to melt both the base material and the wire at ambient temperature. Thus, a system that does not preheat the wire may suffer from a low deposition rate and / or low thermal efficiency. This low deposition rate and efficiency are due in part to the low energy transfer efficiency between the welding arc and the material that is desired to be heated (i.e., the workpiece).

[0018] Additionally, in a system where the wire is a filler material, excessive energy is transferred to the workpiece such that the weld pool has sufficient energy to melt the incoming filler. Due to the high thermal diffusivity of the metal, this excessive energy is easily extracted from the desired heat application location. Adding excessive energy is not desirable because elevated temperatures can cause distortion, alter the metallurgical properties of the workpiece, exacerbate air oxidation, and / or reduce the efficiency of the welding electrical power.

[0019] Conventional preheating methods use Joule or resistive preheating, inductive preheating, laser preheating, and / or infrared preheating. Direct Joule heating involves conducting current to a portion of the filler wire before the filler wire reaches the welding arc (or other means of applying the wire). Direct Joule heating can be performed by passing current from the work through the wire to the point of contact and / or through a first point of contact and through the wire to a second point of contact. Direct Joule heating can include using one or more additional cables to carry the preheating current, and the efficiency of direct Joule heating can depend on the resistivity of the filler wire and the conductivity of the cables.

[0020] Methods for improving Joule heating include reducing the wire diameter and / or increasing the wire feed rate to maintain a high deposition rate. Increasing the wire feed rate is practical only if the process can be stopped or corrected on a human time scale. If the heat in the wire is insufficient to melt it at the weld pool, a hot wire slag may form around the torch. If the wire has excessive heat, the wire may "backfire," in which case sparks and arcs are generated and the material is not deposited in the desired location and / or the torch may be damaged.

[0021] Arc wire heating is applying an arc to the wire. For example, one or more non-consumable electrodes (e.g., tungsten or tungsten alloy electrodes) can be used to create an arc between the non-consumable electrode and the wire. The power delivered via the arc preheats the wire to the desired temperature. An advantage of arc wire heating compared to Joule heating is a reduced current requirement. The arc voltage drop significantly reduces the current requirement and reduces cable / connection losses caused by subsequent high current application. Since the heat is mainly generated by the arc, the conductivity of the filler wire has no significant effect on the overall system efficiency. Thus, arc wire heating maintains similar performance for all metals and alloys. The arc is stable at short arc lengths and slow wire feed rates. The present disclosure relates to devices, systems, and methods for preheating a wire using an (a) arc.

[0022] Additionally, compared to cold wire welding systems or conventional preheating systems, the disclosed preheating system achieves a higher deposition rate. For example, TIG welding using the disclosed arc preheating system can achieve a deposition rate of 200 inches per minute using a wire with a diameter of 0.063". Currently, cold wire TIG welding achieves a deposition rate of 12 inches per minute using a wire with a diameter of 0.063".

[0023] An additional advantage of the present disclosure is that an (arc) can be used to remove the oxide layer of an aluminum welding wire. Aluminum is highly reactive and forms a surface oxide layer when exposed to atmospheric conditions. The oxide layer contains a large amount of water from moisture in the atmosphere. The water provides a source of hydrogen, which can cause porosity in aluminum welds. Therefore, it is advantageous to remove the oxide layer and reduce or prevent the reformation of the oxide layer after cleaning. Accordingly, the disclosed systems and methods can be configured to remove the oxide layer (and any other surface contaminants) of an aluminum welding wire via arc preheating of the wire. A shielding gas is provided to prevent the reformation of the oxide layer on the aluminum welding wire.

[0024] Additionally, the disclosed example systems and methods remove organic contaminants (e.g., hydrocarbons) from the wire during the preheating process. The removal of organic contaminants prevents weld defects caused by a "dirty" wire, which can include porosity in the weld.

[0025] Additionally, the disclosed preheating systems and methods can be retrofitted into existing torches. An existing torch can be modified to include one or more tungsten electrodes configured to preheat the wire via arc preheating.

[0026] Preheating systems using multiple electrodes (e.g., three electrodes connected to the three phases of a three-phase power source) connected to a polyphase power source provide additional advantages. For example, in the disclosed example three-phase preheating system, when three-phase power is applied to the preheating electrodes, there will always be at least two arcs to preheat the wire. The arcs present also assist in the reignition of the commutation arc. Further, since a polyphase system utilizes alternating current, at any given time, at least one arc is the positive electrode when using a polyphase system, which helps in removing contaminants from the aluminum welding wire.

[0027] An example apparatus for preheating a wire disclosed herein includes: an input configured to receive polyphase power; a first tungsten electrode connected to the input via a first conductor, wherein the first conductor is configured to conduct a first phase of the polyphase power received at the input; a second tungsten electrode connected to the input via a second conductor, wherein the second conductor is configured to conduct a second phase of the polyphase power received at the input; and a third tungsten electrode connected to the input via a third conductor, and the third conductor is configured to conduct a third phase of the polyphase power received at the input.

[0028] In some of the disclosed apparatuses for preheating a wire, the apparatus is configured to preheat the wire via arc preheating.

[0029] Some of the disclosed apparatuses for preheating a welding wire further include a first zone that includes a shielding gas and within which the arc preheating occurs.

[0030] Some of the disclosed apparatuses for preheating a welding wire further include a wire guide configured to deliver the preheated welding wire from the first zone to the workpiece; and a gas connector configured to deliver a shielding gas to the first zone to surround the preheated welding wire being delivered to the workpiece.

[0031] In some of the disclosed apparatuses for preheating a welding wire, the polyphase power is three-phase power.

[0032] In some of the disclosed apparatuses for preheating a welding wire, the first tungsten electrode is offset 120 degrees circumferentially from the second tungsten electrode around the outer circumference of the welding wire being preheated, and the third tungsten electrode is offset 120 degrees circumferentially from the second tungsten electrode around the outer circumference of the wire, and the welding wire is typically fed between the first tungsten electrode, the second tungsten electrode, and the third tungsten electrode.

[0033] In some of the disclosed apparatuses for preheating a welding wire, the first tungsten electrode is offset along the length of the welding wire from the second tungsten electrode, the first tungsten electrode is offset along the length of the welding wire from the third tungsten electrode, and the second tungsten electrode is offset along the length of the welding wire from the third tungsten electrode.

[0034] In some of the disclosed apparatuses for preheating a welding wire, during a period of applying three-phase power to the input, there are at least two arcs between at least two of the first tungsten electrode, the second tungsten electrode, or the third tungsten electrode and the welding wire.

[0035] In some of the disclosed apparatuses for preheating a welding wire, the first tungsten electrode, the second tungsten electrode, and the third tungsten electrode are spaced apart substantially evenly around the outer circumference of the welding wire being preheated.

[0036] Some of the disclosed apparatuses for preheating a welding wire further include a neutral conductor electrically connected to the welding wire and configured to be connected to the neutral line of the polyphase power via the input.

[0037] In some of the disclosed apparatuses for preheating a welding wire, the apparatus is a gas metal arc welding (GMAW) torch.

[0038] Some of the disclosed apparatuses for preheating a welding wire further include a contact tip electrically connected to the welding wire and the welding power source.

[0039] In some of the disclosed apparatuses for preheating a welding wire, the polyphase power provides a regulated current.

[0040] In some of the disclosed devices for preheating a welding wire, the polyphase power operates between 50 hertz and 20,000 hertz.

[0041] An example system for preheating a welding wire that is disclosed includes: a polyphase power source; a first tungsten electrode electrically connected to a first phase of the three-phase power source; a second tungsten electrode electrically connected to a second phase of the three-phase power source; and a third tungsten electrode electrically connected to a third phase of the three-phase power source.

[0042] In some of the disclosed systems for preheating a welding wire, the system is configured to preheat the welding wire via arc preheating.

[0043] Some of the disclosed systems for preheating a welding wire further include a first zone that includes a shielding gas and within which the arc preheating occurs.

[0044] Some of the disclosed systems for preheating a welding wire further include: a wire guide configured to deliver the preheated welding wire from the first zone to a workpiece; and a gas connector configured to deliver the shielding gas to the first zone to surround the preheated welding wire being delivered to the workpiece.

[0045] In some of the disclosed systems for preheating a welding wire, the polyphase power is three-phase power.

[0046] In some of the disclosed systems for preheating a welding wire, the first tungsten electrode is offset 120 degrees circumferentially from the second tungsten electrode around the outer circumference of the welding wire being preheated, and the third tungsten electrode is circumferentially offset 120 degrees from the second tungsten electrode around the outer circumference of the welding wire, and the welding wire is typically fed between the first tungsten electrode, the second tungsten electrode, and the third tungsten electrode.

[0047] Figure 1aAn exemplary welding-type system 10 including a welding power source 100 is shown. The power source is supplied to the welding power source 100 via an AC power line 102. The typical range of AC power can be 115 / 230 VAC or 208 to 575 VAC, and can include single-phase power or three-phase power. The welding power source 100 generally supplies power to the welding-type system 10. The welding output terminal 104 provides welding output power via one or more welding cables 106, which are coupled to a modified torch 108 and coupled to the workpiece 110 using a fixture 112. The welding output power can range from 10 amperes to 600 amperes or greater, and from 0 volts in the case of a short circuit to 44 volts or higher in the case of an open-circuit welding arc. Modern welding power sources and systems can provide welding-type power for a variety of welding processes, which can include advanced waveform generation and control in response to dynamic or static conditions at the welding arc.

[0048] The shown welding-type system 10 includes a wire feeder 114 and a gas supply 116. The welding power source 100 can supply power and control to other devices such as the wire feeder 114. In the shown example, the modified torch 108 is coupled to the wire feeder 114 via a cable 118 to supply wire, shielding gas from the gas supply 116, and / or welding-type power to the torch 108 during operation of the welding-type system 10. In some examples, the welding power source 100 can be coupled to the torch 108 and / or supply welding-type power directly to the torch 108.

[0049] As described in more detail below, the torch 108 is configured to preheat the wire via multi-phase arc preheating. The torch 108 includes three or more tungsten electrodes that preheat the fed wire via arc wire heating. In the welding-type system 100, the three or more tungsten electrodes are connected to the welding power supply 100 to provide preheating power and / or connected to a separate preheating power source. Thus, the preheating power source (which can be the welding power supply 100) is configured to provide multi-phase power. For example, in a three-phase system, the three electrodes are connected to three conductors that are connected to the three output phases of the preheating power source. In some examples, the welding power source 100 can output welding-type power to the torch 108 and also output three-phase heating power. As explained in more detail below, in some examples, the three or more tungsten electrodes in the torch 108 can be connected to a dedicated multi-phase preheating power source.

[0050] The exemplary welding system 10 of FIG. 1 has been described as a GMAW system, but the disclosed preheating system can also be used to preheat, for example, tungsten inert gas ("GTAW") filler wire. For example, the modified torch 108 can provide preheated welding filler wire for the following processes: GTAW process, flux-cored arc welding process, metal-cored wire welding process, submerged arc welding (SAW) process, tandem welding process, laser welding process, hybrid welding process, pulsed welding process, spray welding process, and / or any other process that includes adding wire filler metal. As a leading or trailing wire electrode deposition system, in addition to the conventional GMAW arc and electrode deposition, the preheating system can also be used to preheat the wire electrode for deposition into the weld pool. In some examples, a die can be provided to curl the preheated wire from the torch into the weld pool on the workpiece.

[0051] Figure 1b is Figure 1a is a block diagram of an exemplary welding system 10, where the system 10 includes a multiphase preheating power supply 130. As shown, the preheating power supply 130 is a three-phase power source that has three alternating current ("AC") output terminals: output terminal A 132, output terminal B 134, and output terminal C 136. Output terminal A 132 is 120 degrees out of phase with output terminal B 134 and output terminal C 136, and output terminal B 134 is 120 degrees out of phase with output terminal C 136. In some examples, the three-phase power supply 130 is a regulated current power supply (e.g., the three-phase power supply 130 can be controlled to supply a consistent root mean square ("RMS") current). In some examples, the AC output terminals (132, 134, 136) operate at an RMS current between 1 ampere and 100 amperes. In some examples, the RMS current can be less than 1 ampere. In some examples, the frequency of the AC output terminals (132, 134, 136) is between 50 Hz and 20 kHz. The high operating frequency can be used to facilitate arc ignition and reignition and allow for lower operating currents. The preheating power supply 130 can be any power supply configured to provide a multiphase AC output at a desired frequency and current level.

[0052] Phase A 132 is connected to a first tungsten electrode 162 in the torch 108 via a conductor 138. Phase B 134 is connected to a second tungsten electrode 164 in the torch via a conductor 140, and Phase C 136 is connected to a third tungsten electrode 166 in the torch via a conductor 142. The conductors 138, 140, and 142 are connected to the torch 108 via a wire feeder 114. In some examples, between the wire feeder 114 and the torch 108, the conductors 138, 140, and 142 are included in a coupler 118 that also includes a wire 152 fed by the wire feeder 114 from a wire source 150, and a power cable 106. The welding-type power provided by the welding-type power supply 100 is applied to the wire at the torch 108 via a contact tip 160. During a welding operation, a welding-type current creates an arc between the torch 108 and the workpiece 110, and the current returns from the workpiece 110 to the welding-type power supply 100 via the conductor 106. In some examples, the contact tip 160 is closer to the torch tip 170 than the tungsten electrodes (162, 164, 166). In some examples, the tungsten electrodes (162, 164, 166) are closer to the torch tip 170 than the contact tip 160.

[0053] Three conductors 138, 140, and 142 respectively connected to three tungsten electrodes 162, 164, and 166 provide preheating power to the three tungsten electrodes 162, 164, and 166. During operation, there are at least two arcs between any of the three electrodes at any time. The three electrodes 162, 164, and 166 are physically arranged such that an arc jumps from one electrode (one of 162, 164, or 166) to the wire 152, and then to another electrode (one of 162, 164, or 166). For example, the tungsten electrodes 162, 164, and 166 can be circumferentially offset from each other by 120 degrees and spaced apart along the length of the wire 152. In some examples, a neutral line (not shown) (e.g., via the contact tip 160) is connected to the wire 152 and connected to a preheating power supply 130 via a fourth conductor (not shown). In some examples, a neutral conductor connects a fourth tungsten electrode to the preheating power supply 130. The preheating power supply 130 and the electrodes 162, 164, 166 can be configured in a Δ configuration (e.g., without a neutral conductor) or a Y configuration (e.g., using a neutral conductor).

[0054] Figure 2a A diagram showing an isometric view of an example metal inert gas (''MIG'') torch 200 configured to preheat a wire. The torch 200 can implement Figure 1b the torch 108. Figure 2b A cross-sectional view of the MIG torch 200 is shown. The handle of the MIG torch 200 is not shown in Figure 2a and Figure 2bis shown. The torch 200 includes a first tungsten electrode 202, a second tungsten electrode 204, and a third tungsten electrode 205 (not shown for ease of viewing). The first tungsten electrode 202 is connected to a first electrical bus 206, and the second tungsten electrode 204 is connected to a second electrical bus 208 (and the third tungsten electrode 205 is also connected to a third electrical bus). The first electrical bus 206 is connected to a power source via a first power cable 210 (e.g., Figure 1b the power supply 130), and the second electrical bus is connected to a power source via a second power cable 212 (e.g., Figure 1b the power supply 130) (and the third electrical bus is also connected to a power source). The torch 200 is supplied with a shielding gas via a shielding gas hose 214.

[0055] The first tungsten electrode 202, the second tungsten electrode 204, and the third tungsten electrode 205 (which tungsten electrodes may implement electrodes 162, 164, 166) terminate in a chamber 216. An example chamber 216 is a ceramic tube, but may also be another type of chamber configured to contain a shielding gas that travels near the electrode wires of the torch 200. The chamber 216 is supplied with a shielding gas via the shielding gas hose 214. A welding wire is fed into the torch 200 via a wire liner 218. The wire liner 218 is connected to a connection block 220 via a wire liner holder 222 and a threaded wire liner holder 224. The fed welding wire enters the contact tip 226 from the wire liner 218 and then enters the chamber 216 via the contact tip 226. The contact tip 226 is connected to the connection block 220 via a contact tip holder 228. The connection block 220 is connected to a preheating power source via a third power cable 230 (e.g., Figure 1b the power supply 130), and this third power cable provides a neutral line for the preheating circuit.

[0056] An insulator 232 insulates the connection block 220 from the first electrical bus 206, the second electrical bus 208, and the third electrical bus. The preheated welding wire 238 exits the chamber 216 via a wire guide 234. A gas diffuser baffle 236 causes the shielding gas to diffuse around the preheated welding wire 238 (e.g., Figure 1b the welding wire 152) that exits the chamber 216 via the wire guide 234. In some examples, the gas diffuser baffle 236 causes the shielding gas received from the chamber 216 to diffuse. In some examples, the gas diffuser baffle is connected to a gas supply (e.g., Figure 1a the gas supply 116) via a dedicated shielding gas hose (not shown). The welding wire 152 is preheated inside the chamber 216 by arc preheating via an arc generated between the tungsten electrodes and the welding wire. Each of the tungsten electrodes 202, 204, and 205 is connected to a different phase of a polyphase (e.g., three-phase) preheating power source.

[0057] Although Figure 2a and Figure 2b chamber 216 is shown, arc preheating can also occur in any area supplied with shielding gas, for example, via a nozzle or a gas diffuser.

[0058] As described in more detail below, in some examples, the preheating arc can be between each tungsten electrode 202, 204, 205 and the wire. In some examples, the wire is connected to the neutral of a polyphase preheating power source. For example, the contact tip 226 can be electrically coupled to different terminals of the preheating power supply so that the tungsten electrodes 202, 204, 205, the arcs, the wire, the contact tip 226, and the preheating power supply 130 form a preheating circuit (using appropriate electrical leads between the contact tip 226 and the preheating power supply 130 and between the tungsten electrodes 202, 204, 205 and the preheating power supply). FIG. 3 shows an example preheating circuit that may or may not include the contact tip 226. In some examples, a separate neutral wire is not used. The contact tip 226 can be connected to the preheating power source 130 as the neutral wire, and / or the electrodes 202, 204, 205 can be connected in a Δ configuration without a neutral wire.

[0059] The distance between the tungsten electrodes (202, 204, and 205) and the wire is about 0.5 millimeters. In some examples, the positions of the tungsten electrodes 202, 204, and 205 are adjustable. In some examples, the arc gap is adjustable. In some examples, the distance between the tungsten electrodes 202, 204, and 205 and the wire is adjustable to accommodate different wire sizes and / or to adjust the preheating arc voltage.

[0060] Since the tungsten electrodes are connected to an AC polyphase power supply (e.g., a three-phase power supply), at least one arc is always the positive electrode during operation. Compared to electrode negative polarity, an arc with electrode positive polarity (e.g., when the tungsten electrode (202, 204, or 205) has a positive voltage relative to the electrode wire) is more likely to remove the oxide layer on the aluminum wire. Therefore, the aluminum wire is preheated with an electrode positive arc to remove the oxide layer on the aluminum wire. The tungsten electrodes 202, 204, and 205 can be circumferentially and uniformly offset (e.g., each offset from each other by 120 degrees) to remove the oxide layer from all sides of the wire and uniformly preheat the wire. In some examples, the tungsten electrodes 202, 204, and 205 can be evenly spaced around the outer circumference of the wire (e.g., each at 120 degrees ± 30 degrees from each other).

[0061] The exemplary chamber 216 is filled with a protective gas to prevent re-oxidation of the cleaned aluminum welding wire. In some examples, the welding wire 238 may not be pre-heated within the chamber 216 (e.g., the pre-heating may be temporarily turned off or disabled). In some such examples, the nozzle may provide a protective gas to the pre-heated and cleaned aluminum welding wire to prevent re-oxidation of the aluminum welding wire. Additionally or alternatively, the chamber 216 may include a nozzle portion (e.g., a taper at the end of the chamber 216 closest to the welding arc) to concentrate the flow of the protective gas towards the welding pool.

[0062] Figure 3a is a block diagram of an exemplary arc pre-heating system 300, which is embodied in, for example, Figure 1b the torch 108 and Figure 2a and Figure 2b the torch 200. The pre-heating system 300 includes a first tungsten electrode 302, a second tungsten electrode 304, and a third tungsten electrode 306. The electrodes 302, 305, and 306 may implement Figure 1b the electrodes 162, 164, and 166. The first tungsten electrode 302 is electrically connected to the first phase of the pre-heating power source 308, the second tungsten electrode 304 is electrically connected to the second phase of the pre-heating power source 308, and the third tungsten electrode is electrically connected to the third phase of the pre-heating power source 308. The first phase, second phase, and third phase of the pre-heating power source 308 are 120 degrees out of phase with respect to each other.

[0063] The welding wire 310 is fed through the contact tip 312 and delivered to the workpiece 314 via the wire guide 316. The contact tip 312 is electrically connected to the neutral line of the pre-heating power source 308. The contact tip is also electrically connected to a welding-type power source (not shown) to apply a welding-type current to the welding wire 310.

[0064] The welding wire 310 is pre-heated by the arcs between the tungsten electrodes 302, 304, and 306 and the welding wire 310. At any given time, there will be at least two arcs between the electrodes 302, 304, and 306 and the welding wire 310. Figure 3a Three arcs 322, 324, and 326 are shown, and at any given time, at least two of these three arcs will be present. The arcs 322, 324, and 326 jump from the electrodes (302, 304, 306) to the welding wire 310 and then to another electrode (302, 304, 306). The two arcs (two of the arcs 322, 324, and 326) present at any given time are in series, and thus, the total voltage drop across these two arcs is equal to the sum of the voltages across each arc. Therefore, compared to a pre-heating system using a single arc (e.g., between a single tungsten electrode and the welding wire 310), using a three-phase system will reduce the arc current by half while maintaining the same power level.

[0065] As shown, tungsten electrodes 302, 304, and 306 are positioned between contact tip 312 and wire guide 316. In some examples, contact tip 312 may be closer to wire guide 316 than tungsten electrodes 302, 304, and 306. As referenced Figure 2a and Figure 2b explained, arcs 322, 324, and 326 can occur within a chamber filled with a shielding gas to prevent reoxidation of wire 310.

[0066] Figure 3b is an example scaled time curve graph 350 of the voltage at each of electrodes 302, 304, and 306 during a given cycle of three-phase power. In this example, phase 1 is applied to the first electrode 302, phase 2 is applied to the second electrode 304, and phase 3 is applied to the third electrode 306. At time T1, phase 1 connected to the first electrode 302 is commuting, there is a first arc 326 from the third electrode 306 to wire 310, and a second arc 324 from wire 310 to the second electrode 304.

[0067] Time T2 corresponds to the time when phases 1, 2, and 3 are at 60 degrees in the periodic cycle. At time T2, phase 3 connected to the third electrode 306 is commuting, there is a first arc 322 from the first electrode 302 to wire 310, and a second arc 324 from wire 310 to the second electrode 304.

[0068] Time T3 corresponds to the time when phases 1, 2, and 3 are at 120 degrees in the periodic cycle. At time T2, phase 2 connected to the second electrode 304 is commuting, there is a first arc 322 from the first electrode 302 to wire 310, and a second arc 326 from wire 310 to the third electrode 306.

[0069] Time T4 corresponds to the time when phases 1, 2, and 3 are at 180 degrees in the periodic cycle. At time T4, phase 1 connected to the first electrode 302 is commuting, there is a first arc 324 from the second electrode 304 to wire 310, and a second arc 326 from wire 310 to the third electrode 306.

[0070] Time T5 corresponds to the time when phases 1, 2, and 3 are at 240 degrees in the periodic cycle. At time T5, phase 3 connected to the third electrode 306 is commuting, there is a first arc 324 from the second electrode 304 to wire 310, and a second arc 322 from wire 310 to the first electrode 302.

[0071] Time T6 corresponds to the time when the phases of phase 1, phase 2, and phase 3 are 300 degrees in the periodic cycle. At time T6, phase 2 connected to the second electrode 304 is commuting, there is a first arc 326 from the third electrode 306 to the wire 310, and there is a second arc 322 from the wire 310 to the first electrode 302.

[0072] As will be appreciated with reference Figure 3b it, in system 300, when three-phase power is applied to electrodes 302, 304, and 306, the power delivered to the wire 310 is the same (i.e., uniform) at all time intervals.

[0073] Figure 4a , Figure 4b , Figure 5a and Figure 5b Views showing exemplary positioning of the (multiple) preheated tungsten electrodes of the present disclosure.

[0074] Figure 4a A front view of a preheating system 400 using three preheated tungsten electrodes is shown, where each electrode is connected to a different phase of a three-phase power supply. The first tungsten electrode 402, the second tungsten electrode 404, and the third tungsten electrode 406 are configured to preheat the wire 408. The first tungsten electrode 402, the second tungsten electrode 404, and the third tungsten electrode 406 are circumferentially offset (i.e., 120 degrees) in order to uniformly preheat the wire 408 and to uniformly clean the aluminum wire 408. Preheating arcs occur between these three tungsten electrodes 402, 404, and 406 and the wire 408. The arc jumps from an electrode (402, 404, or 406) to the wire 408 and then to another electrode (402, 404, or 406).

[0075] Figure 4b Shows the tungsten electrodes 402, 404, and 406 offset along the length of the wire 408. The tungsten electrodes 402, 404, and 406 are offset in order to ensure that the arc jumps from an electrode (402, 404, or 406) to the wire 408 and then to another electrode (402, 404, or 406), rather than directly from electrode to electrode.

[0076] Figure 5aA front view of a preheating system 500 using four preheated tungsten electrodes is shown, where each electrode is connected to a different phase of a four-phase power supply. The first tungsten electrode 502, the second tungsten electrode 504, the third tungsten electrode 506, and the fourth tungsten electrode 508 are configured to preheat a welding wire 510. The first tungsten electrode 502, the second tungsten electrode 504, the third tungsten electrode 506, and the fourth tungsten electrode 508 are circumferentially offset (i.e., 90 degrees) to uniformly preheat the welding wire 510 and to uniformly clean the aluminum welding wire 510. A preheating arc appears between these four tungsten electrodes 502, 504, 506, and 508 and the welding wire 510. The arc jumps from an electrode (502, 504, 506, or 508) to the welding wire 510 and then jumps to another electrode (502, 504, 506, or 508).

[0077] Figure 5b It is shown that the tungsten electrodes 502, 504, 506, and 508 are offset along the length of the welding wire 510. The tungsten electrodes 502, 504, 506, and 508 are offset to ensure that the arc jumps from an electrode (502, 504, 506, or 508) to the welding wire 510 and then jumps to another electrode (502, 504, 506, or 508) rather than directly from electrode to electrode.

[0078] As used herein, "welding-type power supply" and / or "welding power source" refer to any device that is capable of supplying power for welding, cladding, plasma cutting, induction heating, laser (including laser welding, laser hybrid, and laser cladding), carbon arc cutting or gouging, and / or resistive preheating when power is applied, including but not limited to transformer-rectifiers, inverters, converters, resonant power supplies, quasi-resonant power supplies, switched-mode power supplies, etc., and associated control circuitry and other auxiliary circuitry.

[0079] As used herein, a welding-type system includes any device that is capable of supplying power suitable for welding, plasma cutting, induction heating, CAC-A, and / or hot wire welding / preheating (including laser welding and laser cladding), including inverters, converters, choppers, resonant power supplies, quasi-resonant power supplies, etc., and associated control circuitry and other auxiliary circuitry.

[0080] As used herein, "welding operation" includes the actual welding of two or more physical objects (e.g., resulting in a joint such as welding or brazing), the cladding, texturing, and / or heat treatment of a physical object, and / or the cutting of a physical object, as well as simulated or virtual welding (e.g., visualization of welding without physical welding occurring).

[0081] For convenience, the term "power" is used throughout this specification, but it also includes related measures such as energy, current, voltage, and enthalpy. For example, controlling "power" can include controlling voltage, current, energy, and / or enthalpy, and / or controlling based on "power" can include controlling based on voltage, current, energy, and / or enthalpy. This electrical power measured in watts, which is the product of voltage and current (e.g., V*I power), is referred to herein as "wattage".

[0082] As used herein, "and / or" refers to any one or more of the items in a list connected by "and / or". For example, "x and / or y" refers to any element in the three-element set {(x), (y), (x, y)}. In other words, "x and / or y" means "one or both of x and y". As another example, "x, y, and / or z" refers to any element in the seven-element set {(x), (y), (z), (x, y), (x, z), (y, z), (x, y, z)}. In other words, "x, y, and / or z" means "one or more of x, y, and z". As used herein, the term "exemplary" is used to mean a non-limiting example, instance, or illustration. As used herein, the terms "for example" and "such as" introduce a list of one or more non-limiting examples, instances, or illustrations.

[0083] Although the method and / or system have been described with reference to certain embodiments, those skilled in the art will understand that various changes can be made and equivalent alternatives can be substituted without departing from the scope of the method and / or system. For example, the blocks and / or components of the disclosed examples can be combined, divided, rearranged, and / or otherwise modified. Additionally, many modifications can be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the scope of the present disclosure. Accordingly, the method and / or system are not limited to the particular embodiments disclosed. Instead, the method and / or system will include all embodiments that literally and under the doctrine of equivalents fall within the scope of the appended claims.

Claims

1. A device for preheating a welding wire, the device comprising: An input end configured to receive polyphase power; A first tungsten electrode connected to the input end via a first conductor, wherein the first conductor is configured to conduct a first phase of the polyphase power received at the input end; A second tungsten electrode connected to the input end via a second conductor, wherein the second conductor is configured to conduct a second phase of the polyphase power received at the input end; A third tungsten electrode connected to the input end via a third conductor, wherein the third conductor is configured to conduct a third phase of the polyphase power received at the input end; A first region; A welding wire guide configured to deliver the preheated welding wire from the first region to a workpiece; And A gas connector configured to deliver a shielding gas to the first region to surround the preheated welding wire delivered to the workpiece; Wherein the first tungsten electrode, the second tungsten electrode, and the third tungsten electrode are configured to preheat the welding wire by arc preheating, and wherein the arc preheating occurs within the first region.

2. The device according to claim 1, wherein the polyphase power is three-phase power.

3. The device according to claim 2, wherein the first tungsten electrode is offset 120 degrees from the second tungsten electrode around the outer circumference of the welding wire being preheated, and the third tungsten electrode is circumferentially offset 120 degrees from the second tungsten electrode around the outer circumference of the welding wire, and wherein the welding wire is fed between the first tungsten electrode, the second tungsten electrode, and the third tungsten electrode.

4. The device according to claim 3, wherein the first tungsten electrode is offset from the second tungsten electrode along the length of the welding wire, the first tungsten electrode is offset from the third tungsten electrode along the length of the welding wire, and the second tungsten electrode is offset from the third tungsten electrode along the length of the welding wire.

5. The device according to claim 2, wherein during a period of applying three-phase power to the input end, there are at least two arcs between at least two of the first tungsten electrode, the second tungsten electrode, or the third tungsten electrode and the welding wire.

6. The device according to claim 1, wherein the first tungsten electrode, the second tungsten electrode, and the third tungsten electrode are evenly spaced around the outer circumference of the welding wire being preheated.

7. The device according to claim 1, further comprising a neutral conductor electrically connected to the welding wire and configured to be connected to the neutral line of the polyphase power via the input end.

8. The device according to claim 1, wherein the device is a gas metal arc welding (GMAW) torch.

9. The device according to claim 8, further comprising a contact tip electrically connected to the welding wire and a welding power source and configured to deliver the welding wire to the first region for preheating.

10. The device according to claim 1, wherein the polyphase power provides regulated current.

11. The device according to claim 1, wherein the polyphase power operates between 50 Hz and 20,000 Hz.

12. A system for preheating a welding wire, the system comprising: A polyphase power source; A first tungsten electrode electrically connected to a first phase of the polyphase power source; A second tungsten electrode electrically connected to a second phase of the polyphase power source; And A third tungsten electrode electrically connected to a third phase of the polyphase power source; A first region; A wire guide configured to deliver the preheated welding wire from the first region to a workpiece; And A gas connector configured to deliver a shielding gas to the first region to surround the preheated welding wire being delivered to the workpiece; Wherein the first tungsten electrode, the second tungsten electrode, and the third tungsten electrode are configured to preheat the welding wire via arc preheating, and wherein the arc preheating occurs within the first region.

13. The system according to claim 12, wherein the polyphase power is three-phase power.

14. A system for preheating a welding wire, the system comprising: A polyphase power source; And The device according to claim 1.

15. The system according to claim 14, wherein the first tungsten electrode is offset 120 degrees from the second tungsten electrode around the outer circumference of the welding wire being preheated, and the third tungsten electrode is circumferentially offset 120 degrees from the second tungsten electrode around the outer circumference of the welding wire, and wherein the welding wire is fed between the first tungsten electrode, the second tungsten electrode, and the third tungsten electrode.

16. A device for preheating a welding wire, the device comprising: A contact tip configured to deliver a welding current to the welding wire; A chamber; A wire guide configured to deliver the preheated welding wire from the chamber to a workpiece, wherein the chamber is located between the contact tip and the wire guide; An input configured to receive polyphase power; A first tungsten electrode connected to the input via a first conductor, wherein the first conductor is configured to conduct a first phase of the polyphase power received at the input to generate a first arc between the first tungsten electrode and the welding wire within the chamber according to the first phase of the polyphase power; A second tungsten electrode connected to the input via a second conductor, wherein the second conductor is configured to conduct a second phase of the polyphase power received at the input to generate a second arc between the second tungsten electrode and the welding wire within the chamber according to the second phase of the polyphase power; And A third tungsten electrode connected to the input via a third conductor, wherein the third conductor is configured to conduct a third phase of the polyphase power received at the input to generate a third arc between the third tungsten electrode and the welding wire within the chamber according to the third phase of the polyphase power.

17. The apparatus according to claim 16, wherein the apparatus is configured to preheat the wire at a location near the first tungsten electrode, the second tungsten electrode, and the third tungsten electrode via arc preheating.

18. The apparatus according to claim 17, wherein the chamber includes a shielding gas and the chamber is located near the first tungsten electrode, the second tungsten electrode, and the third tungsten electrode, and wherein the arc preheating occurs within the chamber.

19. The apparatus according to claim 18, further comprising: A gas connector configured to deliver a shielding gas to the chamber to surround the preheated wire delivered to the workpiece.

20. A system for preheating a wire, the system comprising: A first contact tip configured to deliver a welding current to the wire; A chamber; A wire guide configured to deliver the preheated wire from the chamber to the workpiece, wherein the chamber is located between the contact tip and the wire guide; A polyphase power source; A first tungsten electrode electrically connected to a first phase of the polyphase power source; A second tungsten electrode electrically connected to a second phase of the polyphase power source; A third tungsten electrode electrically connected to a third phase of the polyphase power source; And A second contact tip coupled to the polyphase power source, the first tungsten electrode, the second tungsten electrode, the third tungsten electrode, and the second contact tip being configured to provide current to form an arc between the wire and the first tungsten electrode, the second tungsten electrode, and the third tungsten electrode according to the phases of the polyphase power source.

21. The system according to claim 20, wherein the system is configured to preheat the wire at a location near the first tungsten electrode, the second tungsten electrode, and the third tungsten electrode via arc preheating.

22. The system according to claim 21, wherein the chamber includes a shielding gas and is located near the first tungsten electrode, the second tungsten electrode, and the third tungsten electrode, and wherein the arc preheating occurs within the chamber.

23. The system according to claim 22, further comprising: A gas connector configured to deliver a shielding gas to the chamber to surround the preheated wire delivered to the workpiece.

Images