Reduced droplet size of CO2 shielded welding wire

Abstract

To provide droplet granularity reduction of a CO2 shield welded wire.SOLUTION: Provided is an arc-welding system capable of improving droplet transition of molten metal. This system comprises a welding power source having a welding power feeding unit, a welding waveform generator, and a controller. Two flux core welding wire electrodes are connected to the welding power source, and power is fed by a welding output voltage and welding output current generated by the welding power source. A feedback circuit is connected to the welding power source to provide an adaptive response for holding an average welding output voltage. The controller controls the waveform generator and the power feeding unit to superpose a welding current pulse on a welding waveform of a CV flux core arc-welding process using CO2 as a shield gas and generate a changed waveform of a changed CV flux core arc-welding process. The current pulse is superposed at the timing of forming molten metal droplets between the ends of the two electrodes during the changed welding process.SELECTED DRAWING: None

Description

Technical Field

[0001] Cross - reference to Related Applications / Incorporation by Reference This U.S. patent application claims the priority and benefit of U.S. Provisional Patent Application No. 63 / 190,858, filed on May 20, 2021, and incorporates the entire provisional application by reference herein. The entire U.S. Patent No. 10,792,752, issued on October 6, 2020, is incorporated by reference herein.

[0002] Embodiments of the present invention relate to gas - shielded arc welding. More specifically, some embodiments of the present invention relate to systems and methods for reducing the size of molten - metal weld - wire droplets formed in a CO2 gas - shielded arc - welding process (e.g., a flux - cored arc - welding (FCAW) process that uses CO2 gas as a shield).

Background Art

[0003] FCAW can be a semi - automatic or automatic arc - welding process that uses a continuously fed, flux - containing consumable electrode and typically a constant - voltage welding power source. In many cases, an externally supplied shielding gas is used with the flux to provide the necessary protection from the atmosphere. FCAW is often used in construction due to its welding speed and portability. Most of the development of FCAW wires used with CO2 has involved conventional constant - voltage (CV) power sources and constant - speed wire feeders, with an emphasis on improving the composition of the welding wire or, more specifically, the core of the welding wire. CO2 wires are often used to improve penetration and are used in regions where argon and argon - mixed gases are too expensive worldwide. Conventional FCAW welding wires are shielded with CO2 gas and transfer metal droplets to the molten pool in the form of drops or globules. The repulsive force of CO2 pushes the droplet back as it forms, thereby forming larger droplets. For example, when used in a parallel or dual - wire configuration, the droplets can be even larger. Large droplets are often poorly behaved, an operational hindrance, and often result in spatter during the welding process. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] U.S. Patent No. 10,792,752 [Overview of the project] [Means for solving the problem]

[0005] The system and process provide arc control that includes voltage and current characteristics along with superimposed current pulses (e.g., during a CO2FCAW process). The superimposed current pulses play a role in oscillating the droplet back and forth during the droplet growth phase at the end of one or more welding wires. This oscillating motion ensures that the droplet makes contact with the molten pool more stably and quickly, thereby preventing the droplet from growing to an undesirable size.

[0006] In one embodiment, an arc welding system is provided that improves the droplet transfer of molten metal. The system includes a welding power supply having a welding power supply unit, a welding waveform generator, and a controller. Two flux core welding wire electrodes are operationally connected to the welding power supply. The two flux core welding wire electrodes are powered by the same welding output voltage and welding output current generated by the welding power supply. A feedback circuit is operationally connected to the welding power supply to provide an adaptive response to maintain the average welding output voltage. The controller is programmed to control at least the welding waveform generator and the welding power supply unit to superimpose welding current pulses onto the welding waveform of a constant voltage (CV) flux core arc welding process to generate a modified waveform for a modified CV flux core arc welding process. The modified CV flux core arc welding process uses CO2 as the shielding gas. The superimposed wave welding current pulses are superimposed at a timing that facilitates the formation of droplets of molten metal between the ends of the two flux core welding wire electrodes during the modified CV flux core arc welding process. As a result, the droplets of molten metal are smaller in particle size when they transfer into the molten pool than when superimposed wave welding current pulses are not used. In one embodiment, one droplet of molten metal is transferred to the weld pool with every two or more pulses of the superimposed wave welding current pulse. The feedback circuit may include a voltage feedback circuit and / or a current feedback circuit, depending on the various embodiments. The CO2 shielding gas limits the welding output current when it leaves the edge of one of the molten metal droplets, thereby generating an upward force on the droplet away from the weld pool. Each current pulse of the superimposed wave welding current pulse generates an upward force on one of the molten metal droplets away from the weld pool. In one embodiment, the arc welding system includes a user interface configured to adjust at least one of the amplitude, duration, and frequency of the superimposed wave welding current pulse. In one embodiment, the arc welding system includes a welding gun configured to facilitate the passage of two flux-core welding wire electrodes, and at least one wire feeder configured to feed the two flux-core welding wire electrodes to the welding gun.In one embodiment, the welding gun includes a contact tip, and two flux core welding wire electrodes are configured to pass through it side by side and exit through the same orifice of the contact tip.

[0007] In one embodiment, an arc welding method is provided that improves the transfer of molten metal droplets. The method includes superimposing welding current pulses onto the welding waveform of a constant voltage (CV) flux core arc welding process in a welding power source to generate a modified waveform for a modified CV flux core arc welding process. The method also includes powering two flux core welding wire electrodes with the same welding output voltage and welding output current generated by the welding power source during the modified flux core arc welding process using the modified waveform. The method further includes providing CO2 as a shielding gas during the modified flux core arc process. The superimposed wave welding current pulses are superimposed at a timing that facilitates the formation of molten metal droplets between the ends of the two flux core welding wire electrodes during the modified CV flux core arc welding process, resulting in smaller particle sizes when the molten metal droplets transfer into the molten pool than when superimposed wave welding current pulses are not used. In one embodiment, one droplet of molten metal is transferred into the molten pool every two or more pulses of the superimposed wave welding current pulses. CO2 shielding gas limits the welding output current as it leaves the edge of one of the molten metal droplets, thereby generating an upward force on the droplet away from the molten pool. Each current pulse of the superimposed wave welding current pulse generates an upward force on one of the molten metal droplets away from the molten pool. In one embodiment, the method includes adjusting at least one of the amplitude, duration, and frequency of the superimposed wave welding current pulse via a user interface of the welding power supply. One embodiment includes feeding two flux core welding wire electrodes to a welding gun via a wire feeder, such that the two flux core welding wire electrodes pass side by side through the contact tip of the welding gun and exit from the same orifice. In one embodiment, the method includes adjusting the voltage-current(VI) characteristics of a welding power source during a modified flux core arc welding process, and adapting the voltage-current(VI) characteristics to maintain the average welding output voltage and average arc length when two flux core welding wire electrodes are powered by the welding power source during the modified flux core arc welding process.The method also includes feeding back at least one of the welding output voltage or welding output current to the welding power supply controller to facilitate the adaptation of the voltage-current (VI) characteristics.

[0008] Various aspects of the overall concept of the present invention will be readily apparent from the following detailed description of exemplary embodiments, the claims, and the accompanying drawings.

[0009] The accompanying drawings, incorporated herein and constituting part thereof, illustrate various embodiments of the present disclosure. In the drawings, the boundaries of the elements shown (e.g., boxes, sets of boxes, or other shapes) should be understood to represent one embodiment of the boundary. In some embodiments, one element may be designed as multiple elements, and multiple elements may be designed as a single element. In some embodiments, an element shown as an internal component of another element may be implemented as an external component, and vice versa. Furthermore, elements may not be drawn to exact scale. [Brief explanation of the drawing]

[0010] [Figure 1] One embodiment of an arc welding system including a welding power source is shown. [Figure 2] This shows one embodiment of a conventional voltage-current characteristic graph illustrating how the welding power supply is tuned. [Figure 3] This shows one embodiment of a conventional power output curve graph. [Figure 4] This shows one embodiment of the voltage and current traces in a conventional constant voltage (CV) arc welding process. [Figure 5] One embodiment of the voltage and current traces of a conventional constant voltage (CV) arc welding process, with several current spikes and corresponding voltage drops, is shown. [Figure 6] This shows the difference between using CO2 as a shielding gas and using argon as a shielding gas. [Figure 7]The voltage and current traces of an improved arc welding process according to an embodiment of the present invention are shown. [Figure 8] Figure 7 shows one embodiment of molten metal droplet transfer using an improved arc welding process with CO2 shielding gas. [Figure 9] A flowchart of one embodiment of the improved arc welding process disclosed herein is shown. [Figure 10] For example, Figure 1 shows a block diagram of an exemplary embodiment of a controller that can be used in the system. [Modes for carrying out the invention]

[0011] The examples and drawings herein are illustrative and not intended to limit the present invention as determined by the claims and spirit.

[0012] Many power supplies control the FCAW process by adjusting the voltage-current (VI) characteristics based on power, voltage due to current components, and current due to voltage components. In addition to this adjustment, adaptive responses are often added to ensure that the average arc length is maintained even if the contact tip to work distance (CTWD) is varied (changed) by the operator or machine. CO2-shielded FCAW is a highly dynamic process, with droplets forming, growing, and moving very rapidly in space. The VI characteristics respond to this motion by applying a magnetic force induced by the current, which changes in response to voltage changes. The set value of the VI characteristics is adjusted to maintain a relatively constant arc length in adaptive control over long periods. Changes in the contact tip to work distance (CTWD) occur relatively slowly with respect to the change and to the movement of droplets at the end of the consumable welding wire.

[0013] Many conventional transformer designs were conceived based on a voltage that changes at a rate of 1 / 2 to 8 volts per 100 amperes as the current increases. Many modern inverter designs are programmed to mimic this response, with the addition of adaptive control to maintain a true average constant voltage. In one embodiment of the present invention, a VI characteristic with a voltage drop of 5 volts per 100 amperes is employed, and a setpoint of 35 volts is used. When operating at 200 amperes, the result is a voltage drop of 10 volts, resulting in a voltage regulation of 25 volts. Adaptive control over a long period adjusts the setpoint to maintain a preset average of 25 volts.

[0014] According to one embodiment of the present invention, when delta currents (current pulses) are superimposed at a set frequency via programming, the particle size of molten droplets formed at the end of the welding wire electrode can be reduced. Each current pulse induces a magnetic repulsion force on the droplet, pushing it further away from the molten pool. When the current pulse ends and the output returns to the steady-state VI characteristic, the magnetic force is relieved, and the droplet (due to surface tension) bounces back towards the molten pool, often contacting it and initiating metal migration before the droplet becomes too large (beyond the desired particle size). This oscillation facilitates the migration of faster / smaller droplets into the molten pool, thereby making the process more controlled. Furthermore, the adaptive response contributes to adjusting the average voltage and lowering the VI setpoint (in response to current pulses), thereby overcoming the repulsive force acting on the droplet from the feeding wire.

[0015] Referring now to the drawings, which are for the purpose of illustrating exemplary embodiments of the invention only and not of limiting it, FIG. 1 shows one embodiment of an arc welding system 100 including a welding power source 110. The welding power source 110 delivers an output of a welding waveform through at least one welding wire electrode E (e.g., two welding wire electrodes E) to a welding gun / torch 130 to generate a welding arc A. The welding wire electrode E is delivered to the welding operation via at least one wire feeder 150. The wire feeder 150 can be of any known configuration capable of delivering the electrode E to the weld, and in some embodiments, the wire feeder 150 can adjust the wire feed rate of the electrode E based on a signal from the power source 110.

[0016] In one embodiment, two flux-cored welding wire electrodes E are operatively connected to the welding power source 110. The two flux-cored welding wire electrodes E are powered by the same welding output voltage and welding output current generated by the welding power source 110. The welding gun is configured such that the two flux-cored welding wire electrodes can easily pass therethrough. The wire feeder is configured to feed the two flux-cored welding wire electrodes to the welding gun. The welding gun includes a contact tip, and the two flux-cored welding wire electrodes are configured to pass therethrough side by side (see, e.g., Patent Document 1 issued on October 6, 2020, the entire disclosure of which is incorporated herein by reference).

[0017] The overall configuration of the power source 110 can be similar to that of a known power source capable of performing, for example, GMAW and FCAW type welding operations, as long as the power source 110 can function and operate as described above. For example, the power source 110 can be configured similarly to that of a Power Wave® type power source manufactured by The Lincoln Electric Company of Cleveland, Ohio. Of course, embodiments of the present invention are not limited to such a configuration, and this is merely illustrative.

[0018] As shown in FIG. 1, the power supply 110 is configured to receive an input signal through L1, L2, and L3. Although FIG. 1 shows a three-phase input, in other embodiments, a single-phase input can be utilized. The power supply 110 includes a power conversion unit 112, which can receive the input signal and output the signal to an output phase (such as output inverter 114), whereby the output of the power supply 110 can hold a welding arc. The power conversion unit 112 can be composed of a plurality of different components. For example, it can be composed of a rectifier circuit and a buck-boost circuit that can receive a rectified signal and output a constant voltage to the output inverter 114. Of course, in other exemplary embodiments, the output inverter 114 can be a chopper or any other type of output circuit that can output a welding signal in cooperation with the power conversion unit 112. According to one embodiment, the power conversion unit 112 and the output inverter / chopper 114 are collectively referred to herein as a welding power supply unit or simply a power supply unit.

[0019] The power supply 110 also includes a waveform generator 116, which is a circuit that helps to control the output of at least one or both of the power conversion unit 112 and the output inverter 114 to provide a desired welding waveform used to generate the arc A. For example, the waveform generator 116 can be connected to one or both of the power conversion unit 112 and the output inverter 114 (or any output component used) to generate a desired current waveform used to generate and hold the arc A during welding. In addition, the power supply 110 has a controller 118, which can be, for example, any type of CPU or processor-type device that can control the functions and operations of the power supply 110. For example, refer to the controller 1000 in FIG. 10 of this specification. For example, other types of controllers having various electronic circuits (such as logic circuits) and memories can also be used.

[0020] In one embodiment, the controller 118 receives feedback from a current feedback circuit 120 and a voltage feedback circuit 122, which provide current and voltage feedback from the welding arc A, respectively, during welding operations. Using this feedback, the controller 118 can adjust and optimize the operation of the power supply 110 to provide a desired output. For example, in one embodiment, the feedback circuit 122 is operationally connected to (e.g., part of) the welding power supply 110 and provides an adaptive response to maintain the average welding output voltage. In one embodiment, the current feedback circuit 120 includes a current shunt 121 and is part of a current sensing configuration electrically connected to the gun 130. As shown in Figure 1, in some embodiments, the controller 118 is also connected to a wire feeder 150, so that the controller can receive feedback from the wire feeder 150 and control the operation of the wire feeder 150, for example, the wire feeding speed, during welding operations.

[0021] In one embodiment, the controller 118 is programmed to control at least the welding waveform generator 116 and the welding power supply unit to superimpose welding current pulses onto the welding waveform of a constant voltage (CV) flux core arc welding process to generate a modified waveform for a modified CV flux core arc welding process. The superimposed welding current pulses are superimposed at a timing that facilitates the formation of molten metal droplets between the ends of two flux core welding wire electrodes E during the modified CV flux core arc welding process. As a result, the molten metal droplets are smaller in particle size by the time they are transferred to the molten pool than would be in the absence of the superimposed welding current pulses.

[0022] Figure 2 shows graph 200 of one embodiment of a conventional voltage-current (VI) characteristic, illustrating how the molten power supply can be tuned. The voltage-current characteristic in graph 200 has a slope of 5 volts for every 100 amperes of current. For example, if the preset voltage is set to 24 volts, using graph 200, the molten power supply will deliver a current of 360 amperes during the welding process. As droplets of molten metal are formed at the tip of the welding wire electrode during the arc welding process, the droplets move around in space. As the droplets approach the molten pool, the voltage may drop to, for example, 23 volts. Then the current will increase to 380 amperes. Such an increase in current tends to drive the droplets away from the pool, resulting in a longer arc length and a higher voltage. At 25 volts, the current is 340 amperes. With a lower current, the droplets can approach the molten pool. With a tuned system, the arc welding process naturally reaches a state of equilibrium. In one embodiment, adaptive control (e.g., control by controller 118) drives the average voltage of the system to a preset voltage by adjusting the setpoint in graph 200 (described in this example as open-circuit voltage (OCV) = 42 volts) up or down to bring the equilibrium point to a desired voltage.

[0023] Figure 3 shows graph 300 of one embodiment of a conventional power output curve. The power output curve is yet another method for adjusting the welding power supply. Similar to the slope in Figure 2, the power output curve drives the output to an equilibrium point. According to various embodiments, the power setpoint may or may not have adaptive control to drive the system to a preset voltage.

[0024] Figure 4 shows one embodiment of voltage and current traces in a conventional constant voltage (CV) arc welding process. The upper trace 410 represents the unchanged voltage (V), and the middle trace 420 represents the unchanged current (I). A conventional CV arc welding process is tuned by the voltage-current characteristics (e.g., as shown in Figure 2). The adaptive response is shown in the lower trace 430 as a voltage feedback loop to maintain the average voltage or arc length.

[0025] Figure 5 shows one embodiment of voltage and current traces in a conventional constant voltage (CV) arc welding process with several current spikes and corresponding voltage drops. The upper trace 510 represents the unchanged voltage (V), and the lower trace 520 represents the unchanged current (I). The current spikes and corresponding voltage drops indicate where larger droplets are transferred into the molten pool. This event occurs every 1–5 Hz in conventional CV. By pulsed current, transfers occur more frequently, eliminating the need to eliminate current spikes, and consequently reducing spatter.

[0026] Figure 6 shows the difference between using CO2 as a shielding gas and using argon as a shielding gas. A repulsive force is generated when CO2 is used as the shielding gas (left side of Figure 6) and when argon is used as the primary shielding gas (right side of Figure 6). In the case of argon, a wide arc is generated when the current leaves the droplet, and therefore the force is downward, pushing the droplet away from the end of the wire. CO2 limits the current as it leaves the end of the droplet, generating an upward force on the droplet.

[0027] Figure 7 shows voltage and current traces of an improved arc welding process according to one embodiment of the present invention. The upper trace 710 represents the unchanged voltage (V), and the middle trace 720 represents the unchanged current (I). These traces show a new pulse waveform (i.e., a modified waveform for a modified CV flux-core arc welding process) that includes the conventional voltage-current characteristics superimposed with current pulses. Each pulse of current applies an upward repulsive force to the droplet at the end of the welding arc electrode. When the pulse of current is relaxed (attenuated), the force is removed, the droplet bounces back, and in many cases comes into contact with the molten pool. In this way, by applying pulses of current, droplets of molten metal tend to come into contact with and migrate into the molten pool before they become too large. This is particularly beneficial when CO2 is used as a shielding gas. Trace 710 and 720 meet the following conditions: wire feed rate of 300 inches per minute (ipm), 29V / 310 amps, and using twin (two-wire) .045 Ultracore 12C welding wire shielded with 100% CO2 gas.

[0028] In one embodiment, each superimposed wave current pulse represents an additional current of 175 amperes over a duration of 1.5 milliseconds. One droplet of molten metal moves into the molten pool every two or more pulses of the superimposed wave welding current pulse. A user interface (e.g., a user knob, push button, or touchscreen display) can be defined to adjust the amplitude and / or duration and / or frequency of the superimposed wave current pulses. An adaptive response (shown in trace 730 below) maintains an average voltage (e.g., approximately 28 volts). The average current depends on the distance from the tip to the workpiece (CTWD) and can be, for example, 265 amperes. In this embodiment, the process is advancing two .045 or 1.2 mm FCAW wires at a wire feed rate of 250 ipm. Both wires are parallel and passing through the same contact tip and the same contact tip orifice. The same current of the superimposed wave pulse is applied to both wires. In other embodiments, both wires may pass through a different orifice of the contact tip, or only one wire (e.g., 1 / 16 or .052 FCAW wire) may be used.

[0029] Figure 8 shows one embodiment of droplet transfer of molten metal using the improved arc welding process of Figure 7 with CO2 shielding gas. The droplet 810 is shown in multiple stages before, during, and after the current pulse 820. The current pulse 820 repels the droplet 810 upward (indicated by the upward arrow seen in the droplet 810). This is different from conventional pulse welding where the force pushes the droplet into the molten pool. As the current eases (after the peak), the droplet 810 bounces back and is ejected towards the molten pool (indicated by the downward arrow seen in the droplet 810), making contact with the molten pool and tending to transfer.

[0030] Figure 9 shows a flowchart of an improved arc welding process 900 of one embodiment disclosed herein. In step 910 of process 900, the voltage-current (VI) characteristics are adjusted by the welding power supply to maintain a preset voltage (e.g., an average welding output voltage to obtain the average arc length). When timer or frequency conditions are met (e.g., in the controller 118), in step 920 of process 900, a current pulse is superimposed on the welding current. After a peak time (e.g., determined by the controller 118), the arc welding process returns to step 910 and the process is repeated. In this way, the welding current pulse is superimposed on the welding waveform of a constant voltage (CV) flux core arc welding process in the welding power supply to generate a modified waveform for a modified CV flux core arc welding process. Two flux core welding wire electrodes are powered by the same welding output voltage and welding output current generated by the welding power supply during the modified flux core arc welding process using the modified waveform. CO2 is used as a shielding gas in the modified flux core arc welding process. The superimposed wave welding current pulse is superimposed during the modified CV flux core arc welding process at a timing that facilitates the formation of molten metal droplets between the ends of the two flux core welding wire electrodes. As a result, the molten metal droplets are smaller in particle size when they transfer to the weld pool than when the superimposed wave welding current pulse is not used. In this way, improved control of the particle size of molten metal droplets formed at the ends of the welding wire electrodes is achieved, resulting in a more desirable transfer of droplets to the weld pool and reduced spatter.

[0031] Figure 10 shows a block diagram of a controller 1000 in an exemplary embodiment that can be used, for example, in the system of Figure 1 (for example, as controller 118). Referring to Figure 10, the controller 1000 includes at least one processor 1014 (e.g., a microprocessor, a central processing unit, a graphics processing unit) which communicates with several peripheral devices via a bus subsystem 1012. These peripheral devices include a storage subsystem 1024, which includes, for example, a memory subsystem 1028 and a file storage subsystem 1026, a user interface input device 1022, a user interface output device 1020, and a network interface subsystem 1016. The input and output devices enable interaction between the user and the controller 1000. The network interface subsystem 1016 provides an interface to an external network and is connected to corresponding interface devices in other devices.

[0032] User interface input devices 1022 may include pointing devices such as keyboards, mice, trackballs, touchpads or graphics tablets, scanners, touchscreens embedded on displays, voice recognition systems, microphones or other voice input devices, and / or other types of input devices. Generally, the term “input device” shall include all conceivable devices and methods for inputting information into the controller 1000 or into a communication network.

[0033] The user interface output device 1020 may include non-visual displays such as a display subsystem, a printer, or an audio output device. The display subsystem may include flat panel devices such as cathode ray tubes (CRTs) or liquid crystal displays (LCDs), projection devices, or several other mechanisms for producing visible images. The display subsystem may also provide non-visual displays, for example, via an audio output device. In general, the use of the term “output device” includes all conceivable devices and methods for outputting information from the controller 1000 to the user or to other machines or computer systems.

[0034] The storage subsystem 1024 stores programming and data configurations that provide some or all of the functionality described herein. For example, computer executable instructions and data can generally be executed by processor 1014 alone or in conjunction with other processors. The memory 1028 used within the storage subsystem 1024 may include various types of memory, including a main random access memory (RAM) 1030 that stores instructions and data during program execution and a read-only memory (ROM) 1032 in which fixed instructions are stored. The file storage subsystem 1026 can provide permanent storage for program and data files and may include hard disk drives, solid-state drives, floppy disk drives and associated removable media, CD-ROM drives, optical drives, or removable media cartridges. Computer executable instructions and data that implement the functionality of a particular embodiment may be stored by the file storage subsystem 1026 in the storage subsystem 1024 or in other machines accessible by processor 1014.

[0035] The bus subsystem 1012 provides a mechanism for various components and subsystems of the controller 1000 to communicate with each other as intended. Although the bus subsystem 1012 is schematically shown as a single bus, multiple buses may be used in alternative embodiments of the bus subsystem.

[0036] The controller 1000 can be of various types. Due to the ever-changing nature of computing devices and networks, the description of the controller 1000 shown in Figure 10 is merely a specific example intended to illustrate several embodiments. Many other configurations of the controller are possible, having more or fewer components than the controller 1000 shown in Figure 10.

[0037] While the disclosed embodiments are illustrated and described in considerable detail, they are not intended to limit the scope of the accompanying claims or to restrict them in any way to such detail. Needless to say, it is impossible to describe every conceivable combination of components or methodologies in order to illustrate the various aspects of the subject matter. Therefore, this disclosure is not limited to the specific details or illustrative examples illustrated and described. Accordingly, this disclosure is intended to encompass alternatives, improvements, and modifications that fall within the scope of the accompanying claims, satisfying the legal requirements for the subject matter protected under Section 101 of the United States Patent Act. The foregoing descriptions of specific embodiments are provided as examples. From this disclosure, a person skilled in the art will not only understand the general concept of the invention and its associated advantages, but will also notice various obvious modifications and improvements to the disclosed structures and methods. Therefore, it is necessary to cover all such modifications and improvements as falling within the spirit and scope of the general concept of the invention and its equivalents as defined by the accompanying claims. [Explanation of Symbols]

[0038] 100 Arc Welding System 110 Welding Power Supply 112 Power Conversion Unit 114 Output Inverter 116 Waveform Generator 118 Controllers 120 Current Feedback Circuit 121 Current shunt 122 Voltage Feedback Circuit 130 Welding Gun 150 Wire Feeder 200 graphs 300 graphs 410 traces 420 traces 430 traces 510 Trace 520 traces 710 Trace 720 traces 730 traces 810 Droplet 820 Current pulses 1000 controllers 1012 Bus Subsystem 1014 Processor 1016 Network Interface 1020 User Interface Output Device 1022 User Interface Input Devices 1024 Memory subsystem 1026 File Storage Subsystem 1028 Memory subsystem

Claims

1. An arc welding system that improves the droplet transfer of molten metal, It is a welding power source, Welding power supply unit, Welding waveform generator, Controller, and A welding power source including, Two flux-core welding wire electrodes operationally connected to the welding power supply, the two flux-core welding wire electrodes being powered by the same welding output voltage and welding output current generated by the welding power supply, A feedback circuit, which is operationally connected to the welding power supply and provides an adaptive response to maintain the average welding output voltage, Includes, The controller controls at least the welding waveform generator and the welding power supply unit, and uses carbon dioxide (CO2) as the shielding gas. ２ The program is programmed to superimpose a welding current pulse using ) onto the welding waveform of a constant voltage (CV) flux core arc welding process to generate a modified waveform for a modified CV flux core arc welding process. An arc welding system in which superimposed wave welding current pulses are superimposed during the modified CV flux core arc welding process at a timing that facilitates the formation of molten metal droplets between the ends of the two flux core welding wire electrodes by inducing a magnetic repulsion that moves the molten metal away from the molten pool, and as a result the molten metal droplets, when they move into the molten pool, have a smaller particle size than when the superimposed wave welding current pulses are not used.

2. The arc welding system according to claim 1, wherein one droplet of the molten metal is transferred to the molten pool every two or more pulses of the superimposed wave welding current pulse.

3. The arc welding system according to claim 1, wherein the feedback circuit includes a voltage feedback circuit.

4. The arc welding system according to claim 1, wherein the feedback circuit includes a current feedback circuit.

5. The aforementioned CO ２ The arc welding system according to claim 1, wherein the shielding gas limits the welding output current as the welding output current leaves the edge of one of the droplets of molten metal, thereby generating an upward force on the droplet away from the molten pool.

6. The arc welding system according to claim 1, wherein each current pulse of the superimposed wave welding current pulse generates an upward force on one of the molten metal droplets in a direction away from the molten pool.

7. The arc welding system according to claim 1, further comprising a user interface configured to adjust at least one of the amplitude, duration, and frequency of the superimposed wave welding current pulses.

8. The arc welding system according to claim 1, further comprising a welding gun configured to facilitate passage through the two flux core welding wire electrodes.

9. The arc welding system according to claim 8, further comprising at least one wire feeder configured to feed the two flux core welding wire electrodes to the welding gun.

10. The arc welding system according to claim 8, wherein the welding gun includes a contact tip, and the two flux core welding wire electrodes are configured to pass side by side through the contact tip and exit through the same orifice of the contact tip.

11. An arc welding method that improves the droplet transfer of molten metal, The welding current pulse is superimposed on the welding waveform of a constant voltage (CV) flux core arc welding process within the welding power supply to generate a modified waveform for a modified CV flux core arc welding process. During the modified CV flux core arc welding process using the modified waveform, power is supplied to the two flux core welding wire electrodes with the same welding output voltage and welding output current generated by the welding power supply. As part of the aforementioned modified CV flux core arc welding process, carbon dioxide (CO2) ２ ) to be provided as a shielding gas, Includes, The superimposed wave welding current pulse is superimposed during the modified CV flux core arc welding process at a timing that facilitates the formation of molten metal droplets between the ends of the two flux core welding wire electrodes by inducing a magnetic repulsion that moves the molten metal away from the molten pool, and as a result, the molten metal droplets, when they move into the molten pool, have a smaller particle size than when the superimposed wave welding current pulse is not used.

12. The arc welding method according to claim 11, wherein one of the droplets of molten metal is transferred to the molten pool every two or more pulses of the superimposed wave welding current pulse.

13. The aforementioned CO ２ The arc welding method according to claim 11, wherein the shielding gas limits the welding output current when the welding output current leaves the edge of one of the droplets of molten metal, thereby generating an upward force on the droplet away from the molten pool.

14. The arc welding method according to claim 11, wherein each current pulse of the superimposed wave welding current pulse generates an upward force on one of the droplets of molten metal in a direction away from the molten pool.

15. The arc welding method according to claim 11, further comprising adjusting at least one of the amplitude, duration, and frequency of the superimposed wave welding current pulses via a user interface of the welding power supply.

16. The arc welding method according to claim 11, further comprising passing the two flux core welding wire electrodes side by side through the contact tip of a welding gun and out of the same orifice of the contact tip.

17. The arc welding method according to claim 16, further comprising feeding the two flux core welding wire electrodes to the welding gun via a wire feeder.

18. Adjusting the voltage-current (VI) characteristics of the welding power supply during the modified CV flux core arc welding process, During the modified CV flux core arc welding process, the voltage-current (VI) characteristics are adapted to maintain the average welding output voltage and average arc length when power is supplied to the two flux core welding wire electrodes by the welding power source. The arc welding method according to claim 11, further comprising:

19. The arc welding method according to claim 18, further comprising feeding back the welding output voltage to the controller of the welding power supply to facilitate the adaptation process.

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