Metal fabrication system using mechanical oscillation to move structural components toward and away from a workpiece

Abstract

The present application relates to a system (10) including a welding tool (20) configured to receive a welding wire (28) from a wire feeder (24), receive welding power from a power source (54), and supply the welding wire (28) to a workpiece (16, 18, 40) during a welding process. The system (10) also includes a mechanical oscillation system configured to mechanically oscillate a structural component toward and away from the workpiece (16, 18, 40). The structural component is external to the wire feeder (24) and the power source (54). The system (10) further includes a control circuit (42) configured to control the welding power based on feedback related to the welding process.

Description

[0001] Related applications

[0002] This international application claims priority to U.S. Patent Application Serial No. 15 / 722,683, filed October 2, 2017, entitled "METAL MANUFACTURING SYSTEMSAND METHODS USING MECHANICAL OSCILLATION". The entire contents of U.S. Patent Application Serial No. 15 / 722,683 are incorporated herein by reference. Background Technology

[0003] This disclosure generally relates to metal manufacturing systems and methods, and more specifically to systems and methods for joining or constructing metal workpieces using mechanical oscillations of electrodes.

[0004] Various manufactured products can include components made of different materials. It is understood that different materials in a manufactured product can be joined together through fasteners, mating geometries, welding, or other processes. Fasteners or complementary geometries can increase the size or weight of the joint. Three-dimensional welding and additive manufacturing using metals can be used to manufacture durable parts in a controlled and precise manner. Unfortunately, this process can be complex and expensive. Summary of the Invention

[0005] In one embodiment, the system includes a welding tool configured to receive welding wire from a wire feeder, receive welding power from a power source, and supply welding wire to a workpiece during the welding process. The system also includes a mechanical oscillation system configured to mechanically oscillate a structural component toward and away from the workpiece. The structural component is located external to the wire feeder and the power source.

[0006] In another embodiment, the system includes a welding tool configured to receive welding wire from a wire feeder, receive welding power from a power source, and supply welding wire to a workpiece during the welding process. The system also includes a mechanical oscillation system configured to mechanically oscillate a structural component toward and away from the workpiece. The structural component is located external to the wire feeder and the power source. The system further includes a control circuitry configured to control the welding power based on feedback related to the welding process.

[0007] In another embodiment, the system includes a welding tool configured to receive and supply welding wire to a workpiece. The welding tool includes a mechanical oscillation system configured to mechanically oscillate structural components of the welding tool toward and away from the workpiece. The system also includes a control circuitry configured to receive an arc-initiating command, control the mechanical oscillation system to initiate oscillation of the structural components, control a wire feeder to begin feeding the welding wire, determine, at least in part, based on feedback received from sensors, whether an arc has been ignited between the welding wire and the workpiece, control the mechanical oscillation system to stop oscillating the structural components once an arc is determined to be established, and control the wire feeder to increase the wire feed speed to a desired speed. Attached Figure Description

[0008] These and other features, aspects, and advantages of this disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings, in which the same symbols denote the same parts throughout the drawings, wherein:

[0009] Figure 1 These are illustrations of an embodiment of the manufacturing system and its components;

[0010] Figure 2 These are illustrations of an embodiment of the manufacturing system and its components;

[0011] Figure 3 This is an illustration of an embodiment of a manufacturing system with an integrated tool head;

[0012] Figure 4 This is a schematic diagram of the mechanical oscillation system of the manufacturing system;

[0013] Figure 5 It is a graph showing the distance the electrode travels relative to time;

[0014] Figure 6A This is a schematic diagram of the bushings and electrodes of the manufacturing system;

[0015] Figure 6B This is a schematic diagram of the bushings and electrodes of the manufacturing system;

[0016] Figure 7 It is a perspective view of the mechanical oscillation system of the manufacturing system;

[0017] Figure 8 The following time series are shown based on an exemplary controlled short circuit (CSS) waveform implemented by the controller: wire feed speed of the welding wire electrode caused by the mechanical oscillation system, voltage of the electrical power generated by the power source, and current of the electrical power generated by the power source;

[0018] Figure 9Another set of time series is shown based on another exemplary CSC waveform implemented by the controller, including the wire feed speed of the welding wire electrode caused by the mechanical oscillation system, the voltage of the electrical power generated by the power supply, and the current of the electrical power generated by the power supply.

[0019] Figure 10 Another set of time series is shown based on another exemplary CSC waveform implemented by the controller, including: the wire feed speed of the welding wire electrode caused by the mechanical oscillation system, the voltage of the electrical power generated by the power supply, and the current of the electrical power generated by the power supply; and

[0020] Figure 11 It is a flowchart describing the arc initiation process that can be implemented by the system. Detailed Implementation

[0021] One or more specific embodiments of this disclosure will now be described. To provide a concise description of these embodiments, not all features of the actual implementation may be described in the specification. It should be understood that, as in any engineering or design project, the development of any such actual implementation involves making multiple implementation-specific decisions to achieve the developer's specific objectives, such as compliance with system-related and business-related constraints, which may vary depending on the implementation. Furthermore, it should be understood that such development work can be complex and time-consuming, but remains a routine task of design, production, and manufacturing for those skilled in the art who benefit from this disclosure.

[0022] Go to Figure 1 Embodiments of system 10 (e.g., an additive manufacturing system or a welding system) additively form (e.g., print, build) parts 12 from one or more anchoring materials 14. The formed part 12 can be a first workpiece 16, a second workpiece 18, or a joint between the first workpiece 16 and the second workpiece 18, or any combination thereof. In some embodiments, the first workpiece 16 and the second workpiece 18 can be different materials having significantly different physical properties. For example, in one embodiment, the first workpiece 16 can be aluminum, while the second workpiece 18 can be steel. Note that... Figure 1-3 The primary focus is on system 10 as an embodiment of an additive manufacturing system configured to join workpieces 16, 18 to form part 12, or to construct part 12 from one of the workpieces 16, 18, using a plurality of droplets 22 deposited on the workpieces. However, as described in more detail herein, in other embodiments, system 10 may be a welding system configured to join workpieces 16, 18 by generating a welding arc between an electrode 28 and the workpieces 16, 18 to form a weld between the workpieces 16, 18.

[0023] exist Figure 1In the illustrated embodiment, the manufacturing tool 20 deposits a plurality of droplets 22 to form (e.g., print, construct) a part 12 of one or more anchoring materials 14. In some embodiments, the manufacturing tool 20 deposits droplets 22 between a first workpiece 16 and a second workpiece 18. As described in detail below, the manufacturing tool 20 may utilize one or more types of energy to form and deposit droplets 22 to form the part 12. The one or more types of energy utilized by the manufacturing tool 20 may include, but are not limited to, electrical power output, photonic energy (e.g., laser), or any combination thereof. Where the part 12 is a joint between the first workpiece 16 and the second workpiece 18, the manufacturing tool 20 utilizes energy to join the first workpiece 16 and the second workpiece 18 via the part 12.

[0024] Manufacturing tool 20 heats one or more anchoring materials 14 from feeder 24 to form droplets 22 having a desired composition. In some embodiments, mixer 26 of manufacturing tool 20 is configured to receive and combine one or more anchoring materials 14 from feeder 24. For example, mixer 26 may combine multiple anchoring materials 14 to form an electrode 28 having a desired combination of anchoring materials 14. In some embodiments, mixer 26 may form a powder mixture of multiple anchoring materials 14. Electrode 28 and / or powder mixture may form droplets 22. One or more anchoring materials 14 are metallic materials, including but not limited to aluminum alloys, steel alloys, aluminum, iron, copper, manganese, silicon, magnesium, zinc, chromium, titanium, molybdenum, and nickel. As discussed herein, droplets 22 are units of material transition. Upon solidification, each droplet 22 may become a “micro-deposit”, and part 12 is formed from multiple micro-deposits 30.

[0025] Figure 2 An embodiment of manufacturing tool 20 is shown, which guides anchoring material 14 (e.g., electrode 28) into a molten pool 32 of micro-application 30 to form part 12. The anchoring material 14 may be at approximately ambient temperature or a preheated temperature when inserted into the molten pool 32. A portion 34 (e.g., a ball) of the anchoring material 14 is melted by the molten pool 32, thereby forming the micro-application 30 of part 12 without forming defined droplets 22. For example, in some embodiments, the preheated portion 34 of the anchoring material 14 may engage the molten pool 32, thereby forming the micro-application 30 of part 12 via a hot-wire welding process. It is understood that the molten pool 32 may be a recently formed portion of part 12 that has not yet solidified. The energy applied to the molten pool 32 to melt portion 34 may include, but is not limited to, resistance heating, photon (laser) energy, plasma, or induction heating.

[0026] Back Figure 1One or more anchoring materials 14 may include, but are not limited to, powder, solid filament, cored filament, tubular filament, or coated filament, or any combination thereof. In some embodiments, the first anchoring material 36 may be substantially the material of the first workpiece 16, and the second anchoring material 38 may be substantially the material of the second workpiece 18. In other words, the first anchoring material 36 and the second anchoring material 38 may have a chemical composition substantially similar to or compatible with the respective first workpiece 16 and second workpiece 18. For example, the first anchoring material 36 may have only minor differences relative to the material of the first workpiece 16 (e.g., variations only in the percentage of elemental composition, different alloys from the same alloy family). In some embodiments, the anchoring material 14 may include, but is not limited to, brazing or soldering materials having a lower melting temperature than the materials of the first workpiece 16 and / or the second workpiece 18. When one or more anchoring materials 14 are applied, the anchoring material 14 having a lower melting temperature than the first workpiece 16 or the second workpiece 18 may prevent the micro-coating layer 30 adjacent to the first material 16 or the second material 18 from melting. Some embodiments of system 10 may include more than two anchoring materials 14, such as 3, 4, 5, 6, 7, 8, 9, 10, or more anchoring materials 14. For example, a third anchoring material 40 may be provided to manufacturing tool 20. The third anchoring material 40 may have a chemical composition substantially similar to the material of the first workpiece 16 or the material of the second workpiece 18. Additionally, or in an alternative, the third anchoring material 40 may have a chemical composition as an alloying material that provides desired properties (e.g., adhesion, increased or decreased flowability) between the first anchoring material 36 and the second anchoring material 38, and / or the chemical composition of the third anchoring material 40 may provide desired properties (e.g., strength, hardness, electrocorrosion resistance) to part 12.

[0027] The controller 42 of system 10 controls the application of droplets 22 to form parts (e.g., anchors) 12 by micro-deposition material 30. In some embodiments, controller 42 may be a single control system with a single controller, or controller 42 may include multiple control systems or controllers. For example, multiple control systems of controller 42 may be configured to regulate different components or systems of system 10, and / or multiple control systems may be responsive to a single central controller of controller 42. In some embodiments with wire anchoring material 14, controller 42 controls the composition of droplets 22 applied to part 12 by adjusting the relative amounts of one or more anchoring materials 14 supplied to mixer 26 of manufacturing tool 20 (thereby forming electrodes 28). For example, if the first anchoring material 36 is substantially similar to or compatible with the material of the first workpiece 16, controller 42 may increase the relative ratio of the first anchoring material 36 in the electrodes 28 to form (e.g., print) a portion of part 12 near the first workpiece 16. As described herein, the composition of each droplet 22 is based on one or more anchoring materials 14 constituting the respective droplet 22. The droplet 22 is at least partially liquid (e.g., molten). In some embodiments, the droplet 22 may be a liquid anchoring material 14 that encapsulates a solid element of the same or a different anchoring material 14. For example, the manufacturing tool 20 may at least partially melt only the outer layer of the droplet 22.

[0028] In some embodiments, the manufacturing tool 20 uses a mixer 26 to mix (e.g., melt, sinter, compress) multiple anchoring materials 14 into electrodes 28 having a mixed composition. A controller 42 can control the manufacturing tool 20 to form droplets 22 having the mixed composition from the mixed electrodes 28. The controller 42 can adjust the composition of the part (e.g., anchor) 12 by changing the ratio of one or more anchoring materials 14 in the mixed electrodes 28. In some embodiments, the manufacturing tool 20 supplies each of one or more anchoring materials 14 as a separate electrode 28, and the manufacturing tool 20 forms droplets 22 respectively. For example, the controller 42 can control the manufacturing tool 20 to form separate droplets 22 having a different corresponding composition from each of the plurality of electrodes 28. The controller 42 can adjust the composition of the part 12 by changing the ratio of one or more anchoring materials 14 applied as droplets 22 to the part 12.

[0029] In some embodiments, the controller 42 is coupled to a plurality of manufacturing tools 20, each manufacturing tool 20 providing individual anchoring material 14 via its respective electrodes. The controller 42 can control each of the plurality of manufacturing tools 20 to adjust the composition of the part 12 by changing the ratio of anchoring material 14 supplied by each manufacturing tool 20 in droplets 22. Figure 3As shown, in some embodiments, multiple feeders 24 may be combined in an integrated tool head 44 of the manufacturing tool 20 to provide multiple anchoring materials 14 in rows or grids. The integrated tool head 44 may increase the deposition rate of the anchoring materials 14 to form (e.g., print, build) parts 12. The integrated tool head 44 of the manufacturing tool 20 may have multiple mixers 26 to receive the anchoring materials 14 and process them into electrodes 28 and / or powder streams. A controller 42 may control each mixer 26 so that each electrode 28 and / or powder stream has the same composition. In some embodiments, the controller 42 controls one or more mixers 26 so that a corresponding electrode 28 or powder stream has a different composition than an electrode 28 or powder stream from another mixer 26. The integrated tool head 44 enables the manufacturing tool 20 to form multiple layers 46 of parts substantially simultaneously, thereby reducing the production time of parts 12 by reducing the number of passes required for the manufacturing tool 20 to form parts 12. A grid 39 illustrates the first layer 48 of part 12 formed from substantially solidified micro-melt deposits 30. The micro-melt deposits 30 of the second layer 50 formed between the first layer 48 and the third layer 52 of part 12 may be hotter than those of the first layer 48, but sufficiently solidified to support and bond with the melt droplets 22 of the third layer 52. A controller 42 controls the melting rate of the droplets 22 and the rate at which the manufacturing tool 20 forms layers 46, enabling each layer to bond with the previously formed layers 46. For example, the controller 42 may reduce the melting rate or layer formation rate as the manufacturing tool 20 constructs part 12.

[0030] Back to Figure 1 The controller 42 controls the power supply 54 (e.g., a current-regulated power supply) to regulate the power output (e.g., current output, voltage output, photon energy) supplied to the manufacturing tool 20, thereby melting one or more anchoring materials 14 into droplets 22. It is understood that the power supply 54 may include, but is not limited to, an engine-driven generator, a welding power supply, an inverter, a laser, an induction heater, or any combination thereof. In embodiments where the power supply 54 is a welding power supply, the controller 42 may regulate the operation of the power supply 54 (e.g., the voltage level and / or current level of the output power) based on operating states such as welding operations. For example, the controller 42 may regulate the operation of the power supply 54 based on whether the welding operation is in an arc state or a short-circuit state.

[0031] Controller 42 can control power supply 54 to work with pulse welding processes or short-circuit welding processes (e.g., regulated metal deposition (RMD)). TMA similar controlled waveform provides DC or AC power output to electrode 28. In some embodiments, controller 42 controls power supply 54 and / or feeder 24 to provide power output to electrode 28 via manufacturing tool 20, thereby enabling a modified short-circuit welding process (e.g., controlled short circuit) to form part 12. Additionally, controller 42 facilitates part 12 formation by controlling manufacturing tool 20 to extend and retract one or more electrodes 28 during the controlled short-circuit welding process. The power output provided to manufacturing tool 20 melts electrode 28 into droplets 22, which are deposited onto part 12 as micro-deposit 30 via an arc. That is, in some embodiments, electrode 28 is welding wire, manufacturing tool 20 is welding torch (e.g., welding tool) configured for a pulsed welding process or a short-circuit welding process, and feeder 24 is a wire feeder. In such embodiments, welding torch 20 can laminate micro-deposit 30 via an arc, thereby via a pulsed welding process and / or a short-circuit welding process (e.g., RMD). TM The part 12 is formed (e.g., constructed, printed) by the welding wire 28. It is understood that some embodiments of system 10 may include a gas supply 56 configured to provide one or more protective gases to the manufacturing tool 20. The one or more protective gases may include, but are not limited to, argon, carbon dioxide, helium, nitrogen, hydrogen, and combinations thereof. The system may be configured to include a flux delivery system configured to provide one or more fluxes. These fluxes have different compositions to provide different end results, specifically metallurgical results.

[0032] As described above, controller 42 can control the power output for the process of heating electrode 28 using electric arc, and / or magnetic energy, and / or photon energy. Controller 42 can control the rate at which droplets 22 are applied to part 12 by controlling power supply 54. In some embodiments, controller 42 controls heating device 58 (e.g., inductor coil, resistance heater) to preheat electrode 28. Therefore, controller 42 can control the heat applied to electrode 28 to form droplets 22. Additionally, or alternatively, heating devices 58, 60, 62 can respectively perform preheating or postheating of electrode 28, first workpiece 16, and / or second workpiece 18. Preheating electrode 28 can reduce the heat applied to first workpiece 16 and second workpiece 18, thereby reducing the formation of heat-affected zones.

[0033] The droplets 22 added to part 12 as micro-melting material 30 affect the heat added to the first workpiece 16 and the second workpiece 18. The formation of micro-melting material 30 may include, but is not limited to, heating the anchoring material 14 (e.g., electrode 28) to form droplets 22 and cooling the micro-melting material 30 in part 12. It is understood that the heat of the droplets 22 and the cooling rate of the micro-melting material 30 can affect the microstructure of the micro-melting material 30 formed by the respective droplets 22, thereby affecting the properties of part 12. For example, the microstructure of the micro-melting material 30 of part 12 at the first location 64 may differ from the microstructure of the micro-melting material 30 at the second location 66. Furthermore, as discussed herein, the application of each droplet 22 to part 12 may include, but is not limited to, the application rate of the droplets 22 to part 12 and the application location of each micro-melting material 30 on part 12. The controller 42 can control the temperature of the droplets 22, the application (e.g., deposition) rate, and the application location of each droplet 22 to control the heat applied to the workpieces 16, 18. For example, the controller 42 can reduce the inducing factors of the heat-affected zone (HAZ), which can affect the microstructure and properties (e.g., strength, fatigue life) of the workpieces 16, 18 near part 12. The temperature, deposition rate, and application location of the droplets 22 in part 12 affect the amount of heat added to the first workpiece 16 and the second workpiece 18. For example, an arc at 2000°C adds more heat to part 12 than an arc at 1200°C. It is understood that a high deposition rate of droplets 22 (e.g., 60 Hz) can add less heat to part 12 than a relatively low deposition rate of droplets 22 (e.g., 30 Hz). In addition, droplets 22 applied at a first location 64 on the first workpiece 16 add more heat to the first workpiece 16 than droplets 22 applied at a second location 66 on the first workpiece 16. In some embodiments, the controller 42 controls the heating device 58 to influence the application temperature of the micro-melting agent 30 in the part 12, thereby affecting the heat added to the first workpiece 16 and the second workpiece 18. The controller 42 may control the feeder 24 and / or the mixer 26 to control the application rate, and the controller 42 may control the power supply 54 to control the application rate and application temperature of the droplets 22 as micro-melting agents in the part 12. In some embodiments, the robot system 68 coupled to the manufacturing tool 20 may include a control circuit system configured to control the application position of the droplets 22 by moving the manufacturing tool 20 along a coordinate axis 70 via one or more servo motors 69.

[0034] The controller 42 can control the temperature of the droplets 22, the application rate of the droplets 22, and the application location of each droplet 22 in a manner similar to controlling the heat applied to the workpieces 16, 18, to control the heat applied to the previously applied micro-deposit 30. For example, the application rate and temperature of the droplets 22 can affect the cooling rate and microstructure of the previously applied micro-deposit 30. The controller 42 can control the application rate and temperature of the droplets 22 to obtain the desired microstructure for forming each micro-deposit 30 of the part 12. Therefore, the controller can control the composition and / or microstructure of the micro-deposit 30 of the part 12.

[0035] In some embodiments, a first heating device 60 may heat a first workpiece 16 near part 12, and / or a second heating device 62 may heat a second workpiece 18 (e.g., a joint) near part 12. The first heating device 60 and the second heating device 62 may include, but are not limited to, induction coils, resistance heaters, flames, and the like. The first heating device 60 and the second heating device 62 may engage with one or more surface interfaces of the respective first workpiece 16 and second workpiece 18. For example, the first heating device 60 may extend around the first workpiece 16. The controller 42 may control the first heating device 60 and / or the second heating device 62 to preheat the respective workpieces 16, 18 near part 12. It is understood that preheating the workpieces 16, 18 can affect the adhesion from tool 20 to micro-coating 30. For example, increasing the temperature of the first workpiece 16 can increase the adhesion of the micro-coating 30 at a first location 64. In some embodiments, the controller 42 independently controls the first heating device 60 and the second heating device 62, thereby enabling the first workpiece 16 to be preheated to a different temperature than the second workpiece 18.

[0036] As previously stated, the first workpiece 16 may differ from the second workpiece 18. For example, the first workpiece 16 may be aluminum, while the second workpiece 18 may be steel. In some embodiments, the first workpiece 16 and the second workpiece 18 may have the same or different compositions having the same base metal (e.g., aluminum, titanium, iron, galvanized material, high-strength steel). For example, the first workpiece 16 may be nickel-plated steel, while the second workpiece 18 may be relatively high-carbon steel. The first workpiece 16 may have different properties and / or structures than the second workpiece 18. For example, the melting temperature, thermal conductivity, strength, and other properties of the first workpiece 16 and the second workpiece 18 may differ. Additionally, or alternatively, the first workpiece 16 and the second workpiece 18 may have different thermal sensitivities. For example, the first workpiece 16 may be annealed at the melting temperature of the second workpiece 18. Therefore, annealing the first workpiece 16 (e.g., by heating it to the melting temperature of the second workpiece 18) can affect the properties of the first workpiece 16 (e.g., strength, fatigue life).

[0037] It is understood that the heat-affected zone (HAZ) of a metal can be defined herein as a region of metal in which the properties and / or microstructure have been affected by heat. In some embodiments, the controller 42 can independently control the heat applied to the electrode 28, the heat applied to the first workpiece 16 (e.g., via the first heating device 60), and the heat applied to the second workpiece 18 (e.g., via the second heating device 62). The system 10 can reduce the HAZ of the first workpiece 16 and / or the second workpiece 18 by independently controlling the heat applied to these components. For example, if the first workpiece 16 is aluminum and the second workpiece 18 is steel with a higher melting temperature than the first workpiece 16, the controller 42 can control the manufacturing tool 20 to apply droplets 22 near the second workpiece 18 (e.g., steel) with more heat and / or a higher rate than the droplets 22 near the first workpiece 16 (e.g., aluminum).

[0038] As the manufacturing tool 20 moves between the first workpiece 16 and the second workpiece 18, the controller 42 can control the composition and formation of each droplet 22 applied to build the part 12 with the micro-melt coating 30. In this way, the system 10 can control the composition and structure of the part 12 (e.g., the spatial distribution of the micro-melt coating 30) to have a desired set of properties while controlling the HAZ of the first workpiece 16 and / or the second workpiece 18.

[0039] One or more sensors 72 can be used to detect certain operating parameters of system 10. Although sensor 72 is shown as part of welding tool 20, in other embodiments, sensor 72 can be part of any other component of system 10 (including feeder 24, power supply 54, gas supply 56, robot system 68, or any combination thereof). In some embodiments, controller 42 can use the detected operating parameters as feedback to control various operating parameters of system 10. For example, in some embodiments, sensor 72 (e.g., temperature sensor) can measure the temperature and cooling rate of electrode 28, first workpiece 16, and / or second workpiece 18. Feedback from sensor 72 can be stored as a temperature history of electrode 28, first workpiece 16, and / or second workpiece 18. Controller 42 can use this temperature history to control the composition and structure of part 12. In some embodiments, sensor 72 (e.g., optical sensor, proximity sensor, and the like) can measure the position of manufacturing tool 20, first workpiece 16, and second workpiece 18 relative to a set coordinate axis 70. The controller 42 can control the application of droplets 22 to part 12 based at least in part on the relative distances from the first workpiece 16 and / or the second workpiece 18. For example, in some applications, part 12 can be formed with a gradient composition having a first anchoring material 36 and a second anchoring material 38, such that the composition of part 12 adjacent to the first workpiece 16 is compatible with the first workpiece 16 (e.g., forming a strong bond), and the composition of part 12 adjacent to the second workpiece 18 is compatible with the second workpiece 18 (e.g., forming a strong bond).

[0040] The controller 42 can independently control the thermal cycling, peak temperature, and cooling rate of each micro-deposit 30, at least in part, based on the application location in part 12. The controller 42 can independently control the composition and formation of each droplet 22 for the application location based on a set of instructions (e.g., code) executed by the processor 74. The processor 74 can load the instruction set from memory 76, at least in part, based on workpieces 16, 18, and anchoring material 14. In some embodiments, an operator (e.g., from a host computer) can provide the instruction set directly to the controller 42 via an operator interface 78. For example, the operator can load the instruction set for forming part 12 from a 3D model of the anchor (e.g., a computer-aided design (CAD) model) generated by a 3D CAD tool. In some embodiments, the controller 42 can receive and / or generate the instruction set to produce part 12 with the desired composition of anchoring material 14. For example, the controller 42 can use a 3D CAD model of part 12 to control a robotic system 68 to produce part 12 from anchoring material 14. Although controller 42 is described herein as controlling robot system 68, in other embodiments, controller 42 may not be used to control robot system 68. Instead, in such embodiments, a separate control circuitry for robot system 68 may control robot system 68, for example, to control the mechanical oscillations of welding tool 20. Alternatively, in some embodiments, controller 42 may operate in conjunction with the control circuitry for robot system 68. Additionally, or alternatively, an operator may input information about workpieces 16, 18 and anchoring material 14 into operator interface 78, and controller 42 may determine and / or modify a set of instructions to form part 12 with desired characteristics. This set of instructions directs controller 42 to control the composition, formation, and application of each droplet 22 of micro-deposit material 30 to form part 12 with desired characteristics.

[0041] The controller 42 can use input from the sensor 72 to individually control each droplet 22 applied as micro-coating 30 to the part 12. In some embodiments, the controller 42 can adapt a set of instructions, at least in part, based on input from the sensor 72, to compensate for changes to the first workpiece 16, the second workpiece 18, or the part 12. For example, if the input from the sensor 72 indicates a change in the fit of the joint between the first workpiece 16 and the second workpiece 18, the controller 42 can adjust the application position and / or heating of the droplets 22 during the formation of the part 12. Additionally, or alternatively, if the input from the sensor 72 indicates deflection or burn-through of the first workpiece 16 and / or the second workpiece 18 and / or the previous layer, the controller 42 can adjust the application and / or heating of the droplets. If the input from sensor 72 indicates deflection or burn-through of the first workpiece 16 and / or the second workpiece 18 and / or the previous layer, controller 42 can adjust the temperature of the first workpiece 16 and / or the temperature of the second workpiece 18 during the formation of part 12 (e.g., via heating devices 60, 62).

[0042] System 10 can construct part 12 between first workpiece 16 and second workpiece 18 by manually or automatically moving manufacturing tool 20. In some embodiments, it can be done as follows: Figure 1 The electric arc (e.g., jet) causes the droplet 22 to melt. In, as shown... Figure 2 In some embodiments shown, electrode 28 contacts the workpiece and / or part 12, and manufacturing tool 20 applies a corresponding micro-deposit 30 via a short circuit. In some embodiments, an operator initiates or restarts the construction of part 12 by actuating trigger 80 on manufacturing tool 20. Controller 42 determines the position of manufacturing tool 20 relative to workpieces 16, 18 via sensor 72, and controller 42 determines the application location of micro-deposit 30 before forming droplets 22 of the desired composition according to a set of instructions. In some embodiments, robot system 68 controls the movement of manufacturing tool 20 along coordinate axis 70, such as via servo motor 69. Controller 42 may utilize a set of instructions to control robot system 68 to move manufacturing tool 20, thereby applying controlled droplets 22 as micro-deposit 30 to the corresponding location in part 12 based on the set of instructions. Robot system 68 thus enables controller 42 to automatically form part 12 having the desired composition and geometry. In some embodiments, robot system 68 may form (e.g., print, build) part 12 from one or more anchoring materials 14 separate from workpieces 16, 18. The formed part 12 can then be joined with workpieces 16 and 18.

[0043] Furthermore, as mentioned above, although for Figure 1-3The description focuses primarily on additive manufacturing technology (i.e., where the manufacturing tool 20 is an additive manufacturing tool), but in other embodiments, system 10 may alternatively be a welding system 10, where the manufacturing tool 20 is a welding torch configured to supply welding wire (e.g., electrode 28) from a wire feeder (e.g., feeder 24). Thus, in such embodiments, feeder 24 may be a wire feeder comprising components (e.g., wire spool, wire drive assembly, and the like) for feeding the welding wire electrode 28 from feeder 24, rather than comprising components for supplying one or more anchoring materials 14. Alternatively, in such embodiments, manufacturing tool 20 may be a welding torch configured to supply the welding wire electrode 28 received from wire feeder 24 to workpieces 16, 18 to establish a welding arc with one or more of workpieces 16, 18.

[0044] In some embodiments, the manufacturing tool 20 may be a handheld tool, such as a handheld welding torch (e.g., operable by an operator), while in other embodiments, the manufacturing tool 20 may be used for a fully automated or semi-automated process (i.e., fully or partially controlled by a robotic system, such as the robotic system 68 described herein). In any case, the manufacturing tool 20 described herein is external to (i.e., separate from) the feeder 24 and power supply 54 described herein.

[0045] Regardless of whether system 10 is an additive manufacturing system or a welding system, in some embodiments, the integrated tool head 44 of the manufacturing tool 20 can be configured to mechanically oscillate (i.e., move up and down away from and towards the molten pool 32) to further improve the deposition of droplets 22 on part 12. In other words, the integrated tool head 44 (with the electrode 28 and the bushing 100 disposed around the electrode 28 extending through it) can be oscillated to move the electrode 28 and the bushing 100 towards and away from the molten pool 32. Figure 4The diagram illustrates a mechanical oscillation system 102 coupled to an integrated tool head 44. The mechanical oscillation system 102 includes a mechanical linkage assembly coupled to the integrated tool head 44. In the illustrated embodiment, the mechanical linkage assembly includes: a piston 104 coupled or fixedly attached to the integrated tool head 44 (e.g., via pin 106), a cam 108 coupled to the piston 104, and a motor 110 configured to drive the cam 108 to rotate. In other embodiments, the mechanical linkage assembly and / or the mechanical oscillation system 100 may be directly coupled to a bushing 100 to oscillate the bushing 100 toward and away from the workpiece. In operation, by moving the bushing 100 toward and away from the molten pool 32 (e.g., the workpiece), the mechanical oscillation system 102 periodically shortens or lengthens the path that the electrode 28 must travel to the molten pool 32. In this way, the mechanical oscillation system 102 can be used to interrupt or remove the electrode 28 from the molten pool 32 to facilitate the controlled formation of droplets 22. The mechanical oscillation system 102 can also be operated to adjust or control the state of the welding operation. For example, the mechanical oscillation system 102 can be operated to implement or improve the switching of the welding operation between the arc state and the short-circuit state.

[0046] In some embodiments, the mechanical oscillation system 102 may be disposed within the tool 20 (e.g., within the housing of the welding tool 20). In other embodiments, the mechanical oscillation system 102 may be disposed outside the tool 20. For example, in such embodiments, the mechanical oscillation system 102 may be at least partially integrated with the robot system 68 described herein. In any case, in some embodiments, the mechanical oscillation system 102 is disposed outside the feeder 24 and power supply 54 described herein (e.g., outside their housings). It should be understood that during operation, the integrated tool head 44 and bushing 100 are at least partially disposed within the tool 20 and outside the feeder 24 and power supply 54 described herein (e.g., outside their housings).

[0047] As discussed in detail below, a manufacturing tool 20 having the mechanical oscillation system 102 disclosed herein can operate at a substantially fixed frequency and / or a limited (e.g., substantially fixed) travel distance of the integrated tool head 44. Therefore, process simplicity can be increased while significantly reducing the cost of the manufacturing tool 20 and the mechanical oscillation system 102. For example, the mechanical oscillation system 102 of this disclosure enables the droplet 22 to be formed at low welding currents. As will be appreciated, in other embodiments, the mechanical oscillation system 102 may have other components. For example, the mechanical oscillation system 102 may be an electromagnetic system replacing the motor 110, piston 104, and cam 106, comprising coils, magnets, other mechanical linkage assemblies, and the like, to enable the integrated tool head 44 or other structural components to oscillate and thus engage the bushing 100 with the integrated tool head 44. In some embodiments, the mechanical oscillation system 102 may interact directly with the bushing 100 to enable the bushing 100 to oscillate. In other words, the structural component that causes mechanical oscillation by the mechanical oscillation system 102 can be the bushing 100 (i.e., instead of the integrated tool head 44 that indirectly causes mechanical oscillation of the bushing 100).

[0048] As described above, the illustrated mechanical oscillation system 102 (e.g., a mechanical linkage assembly) includes: a piston 104 coupled or fixedly attached to the integrated tool head 44, a cam 108 coupled to the piston 104, and a motor 110 configured to drive the cam 108 to rotate. In some embodiments, the operation of the motor 110 may be controlled and / or regulated by a controller 42. When the motor 110 drives the cam 108 to rotate, the rotation of the cam 108 actuates the piston 104 up and down, as indicated by arrow 112. Therefore, the integrated tool head 44, which may include a sleeve, collar, gas nozzle, contact end, gas diffuser, inlet wire guide, or other components fixed to the piston 104, also travels up and down. In this way, the bushing 100 and electrode 28 are moved toward and away from the molten pool 32. It is understood that the travel distance of the integrated tool head 44 may be selected based on the size and / or geometry of the cam 108.

[0049] When the integrated tool head 44 oscillates upward, the bushing 100 and electrode 28 are pulled away from the molten pool 32, and when the integrated tool head 44 oscillates downward, the bushing 100 and electrode 28 move downward toward the molten pool 32. Of course, when the mechanical oscillation system 102 is operating and moving the integrated tool head 44 up and down, the electrode 28 is being continuously fed downward toward the molten pool 32. Therefore, the electrode 28 can have [a certain characteristic]. Figure 5The line 120 in graph 122 represents the total travel distance. As will be understood, the peak-to-peak amplitude 124 of line 120 can represent the travel distance of the mechanical oscillation system 102 (e.g., piston 104 and integrated tool head 44). The gradual increase in the total travel distance of line 120 can be attributed to the constant feed of electrode 28 by feeder 24.

[0050] As described above, the bushing 100 is disposed around the electrode 28, and the bushing 100 is held and supported by the integrated tool head 44. Therefore, when the mechanical oscillation system 102 oscillates the integrated tool head 44, the integrated tool head 44 similarly oscillates the bushing 100 directly, but may not oscillate the electrode 28 directly. In order to also help promote the oscillation of the electrode 28, the size of the bushing 100 may also be selected so that the electrode 28 can also oscillate.

[0051] exist Figure 6A and 6B The oscillation of bushing 100 and electrode 28 is schematically shown. Integrated tool head 44 and mechanical oscillation system 102 are not shown. Figure 6A In this stage, the integrated tool head 44 and the mechanical oscillation system 102 have not yet caused the bushing 100 and electrode 28 to oscillate upwards. In other words, in... Figure 6A In this configuration, the bushing 100 and electrode 28 extend completely downward toward the molten pool 32. However, in Figure 6B In the diagram, bushing 100 and electrode 28 are shown retracting from the molten pool 32 due to oscillations of the mechanical oscillation system 102. Specifically, bushing 100 and electrode 28 retract a distance of 124 (i.e., Figure 5 (Peak-to-peak amplitude shown). It is understood that a space or gap 130 may exist between the bushing 100 and the electrode 28, since the bushing 100 is a tube or sheath surrounding the electrode 28. This gap 130 can be taken into account when selecting the size of the cam 108 and / or the size and geometry of other components of the mechanical oscillation system 102. Specifically, when the bushing 100 is directly retracted by the integrated tool head 44 and the mechanical oscillation system 102, the bushing 100 can initially retract without a similar retraction of the electrode 28 due to the gap 130 between the bushing 100 and the electrode 28. Once the bushing 100 has retracted directly by the initial amount, the bushing 100 and the electrode 28 can come into contact with each other and engage frictionally, thereby also enabling the electrode 28 to retract. To ensure that the electrode 28 retracts by the desired amount (i.e., distance 124), the initial retraction of the bushing 100 and the gap 130 between the bushing 100 and the electrode 28 can be taken into account when selecting the size and geometry of the components of the mechanical oscillation system 102 (such as the cam 108). In some embodiments, the gap 130 between the bushing 100 and the electrode 28 can be minimized to improve the consistency and accuracy of the oscillating motion of the bushing 100 and the electrode 28.

[0052] The relatively fixed frequency and fixed distance operation of the mechanical oscillation system 102 can increase the simplicity of the manufacturing tool 20 and greatly reduce its cost, thus potentially making it unsuitable for extensive customization. However, the operation of the manufacturing tool 20 can be customized and modified by adjusting, regulating, or otherwise controlling the electrical power of the manufacturing tool 20. In some embodiments, the power supply 54 can be controlled to apply a constant current to the electrode 28. Specifically, if the mechanical oscillation system 102 retracts the electrode 28 from the molten pool 32 by a sufficiently large distance 124, the welding current can be maintained at a fixed level. The fixed current level can be relatively low, but large enough to melt the electrode 28 and form one droplet 22 at a time. A low constant current may not cause disturbance to the molten pool 32.

[0053] However, in other embodiments, one or more simple dynamic variations can be applied to the welding current. For example, controller 42 can adjust the operation of power supply 54 to adjust different dynamic characteristics of the welding current. For example, dynamic waveform shaping can be used, but for simplicity and low cost, the variations can be relatively small. For example, when mechanical oscillation system 102 retracts bushing 100 and electrode 28, and after arcing has begun at a low current, the current supplied by power supply 54 can be increased by controller 42. Increasing the current at this time can help form the next droplet 22, help reduce the likelihood of oscillation of the molten pool 32 reattached to electrode 28, and / or increase the amount of electrode 28 that can be deposited together with the next droplet 22.

[0054] When the mechanical oscillation system 102 returns the bushing 100 and electrode 28 to oscillation toward the molten pool 32, the current can be reduced (e.g., by the controller 42) as the electrode 28 approaches the molten pool 32. Reducing the current can help reduce the likelihood that the electrode 28 will burn out when it attempts to contact the molten pool 32, and / or reduce the likelihood that the electrode 28 and the next droplet 22 will contact the molten pool 32 and be "repelled" by the molten pool 32. In other embodiments, when the bushing 100 and electrode 28 are oscillating toward and / or away from the molten pool 32, the current can be maintained at a level significantly lower than the peak current level of system 10 (e.g., below 100 amps, below 75 amps, below 50 amps, below 25 amps, between 10-100 amps, between 10-75 amps, between 10-50 amps, between 10-25 amps, etc.). This lower current level is typically below 100 amps to avoid spatter, but above 10 amps to avoid arc extinction.

[0055] After the next droplet 22 is formed during the arc, and as the mechanical oscillation system 102 is about to oscillate toward the molten pool 32 again, the current can be kept reduced or further reduced to further reduce disturbance of the molten pool 32. Maintaining a low current (e.g., significantly below the peak current level, as previously described) as the mechanical oscillation system 102 (along with the bushing 100 and electrode 28) oscillates back away from the molten pool 32 also helps to retain the newly formed droplet 22 in the molten pool 32. More specifically, a low current can be maintained during a short circuit, and the current can be briefly increased to form the droplet 22 after the short circuit is cleared. As described above, a low current can also be maintained immediately before the state of the welding operation changes (e.g., immediately before a short circuit or arc). In some embodiments, this can be accompanied by a constant voltage. After the droplet 22 is formed, the current is reduced to reduce disturbance of the molten pool 32 as the mechanical oscillation system 102 oscillates away from the molten pool 32 again.

[0056] To synchronize the operation of the mechanical oscillation system 102 and the power supply 54 to achieve the aforementioned operations, sensor 72 may include a position sensor or other type of sensor that detects the position of the integrated tool head 44 at a specific time. For example, sensor 72 may detect the position of the integrated tool head 44, piston 106, cam 108, bushing 100, electrode 28, or other components. Based on one or more detected positions, controller 42 may adjust the operation of power supply 54 such that the current output of power supply 54 is at a desired level for a specific position of electrode 28. Other types of sensors 72 may also be used to detect other operating parameters that can also be used to synchronize the operation of mechanical oscillation system 102 and power supply 54. For example, one or more sensors 72 may include voltage sensing circuitry and / or current sensing circuitry that can be used to detect the voltage and / or current of power supply 54 and / or motor 110 (e.g., thereby detecting the state of the welding operation, such as a short circuit or arc). Other operating parameters can be detected by sensor 72, such as the operating phase of mechanical oscillation system 102, power supply 54 and / or motor 110, presence of welding arc, short circuit (short circuit per second), angular velocity of motor 110, load on motor 110, wire feed speed, arc length, clearing event, short circuit event, arc event, state change or other operating parameters of system 10.

[0057] Figure 7This is a perspective view of an embodiment of the mechanical oscillation system 102, showing a mechanically linked assembly with a piston 104, a cam 108, and a motor 110. As described above, the bushing 100 can be fixed to the piston 104 via a pin 106 or other connecting features. When the motor 110 drives the cam 108 to rotate, it actuates the piston 104 up and down in an oscillating manner, thereby causing the bushing 100 and the electrode 28 to oscillate up and down. This moves the electrode 28 toward and away from the molten pool 32. In this way, the mechanical oscillation system 102 enables a simple and cost-effective method of operating the manufacturing tool 20.

[0058] In another embodiment, the contact tip moves together with the bushing 100. In this case, the contact tip has higher friction than the bushing and facilitates tighter control. Furthermore, this movement inherently alters the distance from the current conduction point in the contact tip to the weld. When the contact tip is in a largely fixed position, the distance between the current conduction point in the contact tip and the weld is almost constant. In either case, the key effect of retracting the welding wire from the molten weld is achieved. Similarly, in other embodiments, the bushing 100 can be moved together with the gas nozzle, collar, sleeve, or other structural components surrounding or connected to the bushing 100.

[0059] The embodiments described herein typically require the deposition of droplets 22 in a highly controlled manner. One approach is to use highly controlled welding processes, such as tungsten inert gas (TIG) applications and low heat input metal inert gas (MIG) applications. When strictly controlled, most welding processes under ideal conditions can be replicated from additive manufacturing processes. The most controlled welding processes include Accu-Pulse. TM RMD TM Controlled short circuit (CSC) welding process. RMD TM CSC processes are short-circuit welding processes. These short-circuit welding processes are relatively efficient for additive manufacturing because they involve relatively low heat. In contrast, spray welding and pulsed spray welding processes are relatively hot, thus producing a larger molten pool, which is less efficient for precise builds (e.g., the molten pool and the resulting weld bead tend to become too wide).

[0060] The CSC process is described in more detail in U.S. Patent Nos. 6,963,048, 6,969,823, and 6,984,806, the entire contents of each of which are incorporated herein by reference. This CSC process utilizes electrical power modulation and forward / reverse wire movement to maximize metal deposition. Typically, in the CSC process, a short-circuit state is entered by advancing the wire until it contacts the molten pool, and then an arc state is entered by retracting the wire until it no longer contacts the molten pool, at which point an arc is formed. The CSC process typically employs sophisticated power output control techniques to control the energy delivered to the weld. By separating the control of the transitions between states from the control of the energy delivered to the weld, the CSC process allows for better control of each state.

[0061] Typically, CSC systems require the ability to advance and retract the welding wire. Traditional CSC systems utilize mechanical devices (such as stepper motors) to control the wire's advance and retraction. For example, such CSC welding systems dynamically control the motor direction (e.g., forward / reverse, clockwise / counterclockwise) to rotate the drive wheel of the wire feeder. Therefore, in such CSC systems, when the welding wire is being fed towards the weld, the mechanical device used in traditional CSC systems has a relatively high momentum level in the feed direction, which must be overcome to reverse in the opposite direction to retract the welding wire.

[0062] Furthermore, as described herein, conventional short-circuit processes are relatively colder than pulsed or spray-welded MIG processes. One problem with conventional short-circuit transitions is that they typically rely on a “pinch effect” to separate the molten ball from the solid wire. The pinch effect is driven by a relatively high current. When the ball separates, the plasma is re-ignited at this relatively high current level. This results in a relatively strong plasma force pushing the molten pool away from the wire tip, which can lead to undesirable molten pool disturbances. Short-circuit (e.g., RMD) processes are described in more detail in U.S. Patent Nos. 6,326,591 and 6,800,832. TM The two patents mentioned are incorporated herein by reference in their entirety, a process that serves as an alternative solution. Typically, RMD... TM The pinching effect is still used, but the timing of the ball's separation from the wire is predicted, and the current is reduced before this separation occurs. This prediction method works well and is a close alternative. However, by comparison, the CSC process described herein and this invention do not require relatively high currents to separate the ball, thus eliminating the need for prediction and the risk of igniting the plasma at relatively high currents. Specifically, the reverse wire action eliminates the need for large currents to "pinch" the molten ball away from the wire end. By eliminating this peak current, compared to conventional short circuits or even RMD... TMThe welding process is more stable and can be performed at a lower temperature.

[0063] Certain embodiments of this disclosure implement systems and methods for providing welding-type power using a wire feeder 24 that supplies wire electrode 28 to an electric arc and a power source 54 that supplies power to the electric arc. The mechanical oscillation system 102 described herein facilitates the movement of the wire electrode 28 toward and away from the electric arc. In some embodiments, a controller 42 controls the oscillating motion, controls the power source 54 to provide a desired average arc current, controls the wire reel of the feeder 24, the wire drive assembly, and such to control the average wire feed speed of the wire electrode 28, or any combination thereof. Furthermore, in some embodiments, the controller 42 may include: various control modules, such as an average arc current or arc voltage control module, to control the current or voltage output of the welding power from the power source 54 to a desired average arc current or voltage; and / or a short-circuit detection feedback circuit.

[0064] In other embodiments, the control of the oscillating motion, the control of the welding power output of the power supply 54, and the control of the wire feed speed may not be controlled by the same controller 42. Instead, in such embodiments, each control may be configured to operate at nominal settings, and each control may be robust enough to respond to the desired response of other components in system 10. These embodiments can result in a reduction in the complexity of system 10. For example, a strong and relatively rapid (e.g., on the order of 20 kHz) constant voltage (CV) response during the arc phase and / or short-circuit phase will modulate the current much faster than the short-circuit frequency and affect the melting rate to maintain the required voltage.

[0065] Voltage is a strong indicator of arc length. In some embodiments, controller 42 can also automatically adapt to slower timescales by adjusting the nominal settings of system 10. For example, if controller 42 detects a relatively short arc length during one or more arc phases, it can reduce the nominal wire feed speed, or it can increase the initial current of power supply 54 for the arc phase or short phase, or it can change the oscillation frequency by controller 42 (e.g., by adjusting the speed of motor 110 of mechanical oscillation system 102). Each such adjustment will tend to increase the average arc length.

[0066] In some embodiments, controller 42 may use “coordinating” control, thereby changing the nominal settings of other systems when a setting in one system is changed. For example, if the average wire feed speed increases, the power level of power supply 54 may be increased (e.g., by increasing the voltage, current, or both of power supply 54) and / or the oscillation frequency of mechanical oscillation system 102 may be increased. In other words, typically, the power level of power supply 54 (e.g., voltage, current, or both) may be synchronized with the mechanical oscillation of mechanical oscillation system 102. For example, in some embodiments, this may be done based on a matching settable. Adjusting one setting sends the adjustment to other components in system 10. Coordination is a common term in the welding industry that describes a system in which multiple parameters are changed to ideal nominal matching settings by adjusting one parameter.

[0067] Therefore, the embodiments described herein contribute to relatively low cost and improved performance compared to conventional MIG welding processes. Specifically, the mechanical oscillation system 102 described herein enables relatively low-cost oscillation of the wire electrode 28 while still enabling CSC-type processes. Conventional MIG welding processes (including CSC processes) can have short circuits of approximately 25 to over 200 times per second. The embodiments described herein reduce costs by minimizing the mass that must be moved. In some CSC welding systems, a stepper motor must change the direction of the wire, bushing, wire feed rollers, and the motor itself. The inertia of the motor itself is arguably the greatest. In contrast, in the embodiments described herein, the motor 110 does not change direction, thus eliminating the requirement to decelerate and re-accelerate the armature of the motor 110 in the opposite direction at the oscillation frequency of the process (e.g., between 20 and 200 cycles / second in some embodiments). Some CSC welding systems also require the cost and complexity of "H-bridge" electric drives, as well as complex controllers for managing the electric drives, which are not required in the embodiments described herein.

[0068] Furthermore, oscillation at a substantially fixed frequency and / or a substantially fixed travel distance simplifies system 10 and reduces cost. In some embodiments, an engraving machine or a low-cost tattoo machine can be used as part of the mechanical oscillation system 102, with a relatively fixed travel distance and a relatively fixed oscillation frequency. The relatively fixed travel distance and relatively fixed oscillation frequency significantly reduce the cost of system 10 (e.g., at least in part due to a trade-off between flexibility and cost). Some conventional CSC systems use stepper motors to dynamically advance and retract the welding wire, where the distance and speed of each individual forward and backward movement are independently and individually controlled. In contrast, in the embodiments described herein, the oscillation distance of the mechanical oscillation system 102 is relatively fixed, for example by the size of the cam 108, and the oscillation speed of the mechanical oscillation system 102 can be controlled, for example, by adjusting the speed of the motor 110 (i.e., resulting in more or fewer short circuits per second). In some embodiments, a stepper motor can be used to provide more dynamic forward and retraction movements, but this may increase the cost and complexity of system 10.

[0069] As described herein, controller 42 can be used to control the electrical power of the welding process to compensate for the relatively lack of flexibility of the mechanical oscillation system 102. Specifically, since the frequency and distance of the mechanical oscillations are relatively fixed during the operation of the mechanical oscillation system 102, controller 42 can control the electrical power of the welding process (e.g., the welding power supplied by power source 54) based on feedback related to the welding process (e.g., timing of welding process phases such as short-circuit phase 154, arc reconstruction phase 158, and the like, timing of the mechanical oscillations of the mechanical oscillation system 102, and the like). For example, since the period of the mechanical oscillations of the mechanical oscillation system 102 remains relatively fixed during the operation of the mechanical oscillation system 102 due to the relatively fixed frequency and distance of the mechanical oscillations, controller 42 can synchronize the supply of welding power from power source 54 with the period of the mechanical oscillations of the mechanical oscillation system 102. For example, in some embodiments, controller 42 may periodically calibrate the delivery of welding power from power source 54 based on feedback related to the welding process (e.g., timing of welding process phases (e.g., short-circuit phase 154, arc reconstruction phase 158, and the like), timing of mechanical oscillations of mechanical oscillation system 102, and the like), for example, using sensor feedback (e.g., via sensor 72 described herein) to detect the exact timing of short circuits, arcs, and the like, and adjusting the timing of transitions between states of welding power based on that feedback (e.g., see [link to relevant documentation]). Figure 8-10 ).

[0070] As per the above reference Figure 5The welding wire electrode 28 will have an oscillating motion combined with a steady but relatively slow movement of the welding wire electrode 28 moving forward at a fixed but slow rate. In contrast to retracting the welding wire electrode 28 by lifting the entire welding torch 20 or reversing the feed motor, the embodiments described herein force the welding wire electrode 28 to traverse a relatively long path. Assuming that the source of the welding wire electrode 28 (e.g., wire feeder 24) and the weld pool 32 are in largely fixed positions, the welding wire electrode 28 can be retracted from the weld pool 32 by forcing it to travel a relatively long distance (see, for example, [link to previous document]). Figure 6A and 6B Specifically, the bushing 100 has a substantially fixed length. Pulling the bushing 100 upwards and out of contact with the welding torch 20 will actually result in a longer bushing 100. When the bushing 100 changes direction, the excess space between the bushing 100 and the welding wire electrode 28 must be absorbed. This small distance must be increased to the amount by which the bushing 100 must move. The minimum amount of excess space between the bushing 100 and the welding wire electrode 28 is ideal.

[0071] As described above, the mechanical oscillation system 102 can have a substantially fixed oscillation frequency and / or a substantially fixed oscillation travel distance to simplify system 10 and reduce its cost. As described herein, the term "substantially fixed" or "relatively fixed" is intended to describe properties that vary substantially little (e.g., less than 5%, less than 4%, less than 3%, less than 2%, less than 1%, or even less) during operation. It should be understood that in some embodiments, the speed of the motor 110 of the mechanical oscillation system 102 can be adjusted by the controller 42, thereby adjusting the frequency of the mechanical oscillation. However, once the speed of the motor 110 is adjusted by the controller 42, the frequency of the mechanical oscillation will remain substantially fixed during operation of the mechanical oscillation system 102. Conversely, in some embodiments, the distance of the mechanical oscillation remains substantially fixed, at least in part due to the inherent physical characteristics of the components of the mechanical oscillation system 102.

[0072] One problem with the substantially fixed oscillation frequency and substantially fixed oscillation travel distance is that either of these characteristics may not actually be synchronized with the molten pool 32 and the actual ball. However, as described herein, the controller 42 can dynamically adjust the electrical power (e.g., voltage, current, or both) generated by the power source 54 to compensate for the relatively lack of precision of the mechanical oscillation system 102 (i.e., the lack of operational flexibility due to the wider range of oscillation frequencies and travel distances). Specifically, the electrical power generated by the power source 54 is controlled by the controller 42 based on feedback related to the welding process (e.g., timing of welding process phases such as short-circuit phase 154, arc reconstruction phase 158, and the like), timing of the mechanical oscillations of the mechanical oscillation system 102, and the like). The simplest solution could be to use a conventional constant current (CC) welding power source as the power source 54. In such an embodiment, if the oscillation retraction distance is large enough, the welding current from the power supply 54 can be set at a relatively fixed level, just high enough to melt the wire electrode 28 one ball 34 at a time, but still relatively low enough to cause little disturbance to the molten pool and prevent molten material from spraying out of the molten pool 32 or from the end of the wire electrode 28 (i.e., commonly referred to as spatter). In some embodiments, the controller 42 may use a control loop to dynamically adjust the average current and / or average wire feed speed to maintain a stable process.

[0073] In some embodiments, the process can be improved relative to a relatively constant current process by dynamically varying the welding voltage and / or current (i.e., the "waveform"). As mentioned above, examples of waveform shaping include Accu-Pulse. TM RMD TMAnd CSC welding process. Furthermore, it is desirable to implement a relatively simple and low-cost system 10, and therefore the waveform changes implemented by the controller 42 can include increasing the current after the welding wire electrode 28 has separated from the molten pool 32 (and the plasma has been re-ignited). This helps to form the next ball 34, helps to ensure that possible molten pool oscillations do not reattach to the welding wire electrode 28, and helps to increase the amount of welding wire electrode 28 that can be deposited, as this is a "safe" position to increase energy into the process without increasing the risk of an unstable process. Furthermore, the waveform changes implemented by the controller 42 can include decreasing the current when the welding wire electrode 28 is about to contact the molten pool 32. This helps to reduce the chance of the welding wire electrode 28 burning out when attempting to contact the molten pool 32, and helps to reduce the chance of the welding wire electrode 28 and the molten ball 34 contacting the molten pool 32 and being "repelled" by a poorly timed pinching event. Furthermore, the waveform changes implemented by the controller 42 can include decreasing the current when the welding wire electrode 28 is about to separate from the molten pool 32. This helps to reduce the force of the plasma when it is re-ignited. Reducing this force (i.e., from no plasma to plasma) reduces molten pool disturbance, reduces spatter, and helps to stabilize the process.

[0074] In some embodiments, if the arc has not yet been re-established and retraction is complete or about to be complete, the controller 42 may increase the current to force the molten column to clamp between the molten pool 32 and the wire electrode 28. In some embodiments, if the wire electrode 28 is embedded in the molten pool 32 and the controller 42 determines that retraction of the mechanical oscillation system 102 will reignite the plasma, a conventional clamping event may be required. In this case, the controller 42 may adjust the waveform to include a relatively high current event, thereby liquefying the wire electrode 28 and / or clamping the molten region of the wire electrode 28 and / or the molten pool 32, and reigniting the arc. Additionally, in some embodiments, if the clamping event would exert too much force on a relatively delicate 3D part, the controller 42 may stop the process and a manual reset of the system 10 is required.

[0075] Figure 8 The following time series are shown based on an exemplary CSC waveform implemented by controller 42: the wire feed speed (WFS) of the welding wire electrode 28 caused by the mechanical oscillation system 102 (i.e., trace 132), the voltage (V) of the electrical power generated by power supply 54 (i.e., trace 134), and the current (I) of the electrical power generated by power supply 54 (i.e., trace 136). Figure 8 As shown, and as described in more detail herein, the wire feed rate of the welding wire electrode 28 typically oscillates between a positive feed rate 138 and a negative feed rate 140 (i.e., during retraction), wherein the positive feed rate 138 has a greater magnitude than the negative feed rate 140, such that the welding wire electrode 28 advances over time, as... Figure 5 As shown. The axis 142 of each trace 132, 134, 136 is intended to represent the zero value of each corresponding parameter (i.e., wire feed speed, voltage, and current). Figure 8 This shows that the positive feed rate region above axis 142 (e.g., corresponding to positive feed rate 138) is higher than the negative feed rate region below axis 142 (e.g., corresponding to negative feed rate 140). This also shows that the total feed rate is a combination of a constant forward feed rate plus oscillations caused by the mechanical oscillation system 102.

[0076] like Figure 8 As shown, the current remains relatively low during the short circuit (e.g., interval 144). After the short circuit is cleared (e.g., interval 146), the current is increased for a short period (e.g., between 0.5 and 5.0 milliseconds in some embodiments) to form the sphere 34. In some embodiments, this arc phase may have a constant voltage (CV) characteristic, which has the additional advantage of increasing or decreasing the current at the sphere-forming peak 148, thereby forming larger or smaller spheres 34 depending on the proximity of the wire electrode 28 to the molten pool 32 (e.g., arc length). This helps to balance the melting rate with the average forward wire feed rate. The CV characteristic can be implemented by the duration or amplitude of the sphere-forming pulse.

[0077] Then, after the ball 34 is formed, the current can be reduced to a relatively low level 150 (e.g., interval 152). In some embodiments, this can have a constant current (CC) characteristic. However, in other embodiments, a CV characteristic at a relatively low voltage level can be implemented, which can help match the average wire feed rate to the melting rate. Ideally, this relatively low current 150 will result in minimal force from the plasma between the ball 34 and the molten pool 32 as the wire electrode 28 approaches the molten pool 32, and will result in minimal spatter or ball repulsion when the ball 34 contacts the molten pool 32. The current will remain relatively low, waiting for the wire electrode 28 to retract from the molten pool 32 by the mechanical oscillation system 102, leaving the ball 34 in the molten pool 32. In some embodiments, a current pulse can be implemented during a short circuit (e.g., interval 144), which may tend to increase the resistive heating of the wire electrode 28, but if the short circuit is cleared while still at a relatively high current level (e.g., peak 148), the current pulse may also generate spatter. In some embodiments, the amplitude of the pulse current may be affected by a constant voltage (CV) control loop, the amplitude or duration of which may be limited by the controller 42 to ensure that the current is not at a relatively high level when the short circuit is cleared.

[0078] It should be noted that a constant voltage (CV) state often provides a certain amount of dynamic power to help system 10 match the melting rate with the average wire feed speed. This dynamic melting improves the robustness of the process. Conversely, a process with completely constant current (CC) power is relatively more difficult to match with a fixed wire feed speed. Figure 9 Another set of time series is shown based on another exemplary CSC waveform implemented by controller 42, including the wire feed speed (WFS) of the welding wire electrode 28 caused by the mechanical oscillation system 102 (i.e., trace 132), the voltage (V) of the electrical power generated by power supply 54 (i.e., trace 134), and the current (I) of the electrical power generated by power supply 54 (i.e., trace 136). Specifically, Figure 9 The diagram illustrates one oscillation of the wire electrode 28 during each ball transition (e.g., one cycle of positive feed rate 138 and negative feed rate 140). During a single ball transition, the wire electrode 28 may indeed have multiple oscillations. Specifically, if the ball 34 forms a pulse that melts the wire electrode 28 sufficiently, two oscillation cycles of the mechanical oscillation system 102 may be required before the wire electrode 28 has advanced far enough to contact the molten pool 32 again. Typically, the primary function of the mechanical oscillation system 102 is to pull the wire electrode 28 out of the molten pool 32 while leaving the ball 34 in place.

[0079] Back Figure 9During the short-circuit state (e.g., interval 154), voltage can be detected while the welding wire electrode 28 is being advanced at a positive feed rate 138. For example, in some embodiments, the sensor 72 described herein may include a voltage sensing circuitry system that detects the voltage and transmits the detected voltage to the controller 42 (e.g., so that the controller 42 can determine, for example, by detecting a significant drop in voltage, that the short-circuit state 154 has been initiated). For reference, in GMAW welding, the short-circuit phase typically has a voltage 10-15 volts lower than the arc phase. That is, approximately 10 volts are required to ionize the welding gas to generate an arc. During the short-circuit state 154, the current is maintained at a relatively low constant current (CC) level 156 (e.g., less than 50 amps in some embodiments, or between 5-30 amps) so as not to generate excessive spatter or molten pool disturbance during short-circuit clearing. In some embodiments, once short-circuit state 154 is established, in addition to synchronizing the welding power with the mechanical oscillation, controller 42 may also send a command to mechanical oscillation system 102 to retract the wire electrode 28 at a negative feed rate 140. In some embodiments, an index sensor may be used to provide explicit feedback to controller 42 on the position of the wire electrode 28 (i.e., whether the wire electrode 28 is in the retracted or forward position). In some embodiments, sensor 72 may be used by controller 42 to determine, for example, by detecting voltage, when short-circuit state 154 has ended, thereby allowing controller 42 to determine that the short circuit has been cleared based on a significant increase in voltage.

[0080] Subsequently, during the arc reconstruction state (e.g., interval 158) that occurs immediately following the short-circuit state 154, the controller 42 maintains the current at a relatively low constant current (CC) level 156 for a short period of time (e.g., between 100-300 milliseconds, between 150-250 milliseconds, or about 200 milliseconds in some embodiments) so that the arc can be reconstructed with a relatively low current while the wire electrode 28 is retracting.

[0081] Once the arc is re-established, and during the ball-forming state (e.g., interval 160) that occurs immediately after the arc re-establishment state 158 as the wire electrode 28 continues to retract, the controller 42 increases the current to a relatively high current level 162 to burn the wire electrode 28 back from the molten pool 32 and form the next ball 34. As shown, in some embodiments, a constant current (CC) ramp 164 may be implemented by the controller 42 to drive a relatively rapid current jump. In some embodiments, the extent of the CC ramp 164 (i.e., the rate at which the current increases from a relatively low constant current level 156 to the peak current level 162) may be determined by the controller 42 based at least in part on the size (e.g., diameter) of the wire electrode 28 or a particular alloy and / or the average wire feed rate. Once the peak current level 162 is reached, the controller 42 may implement a constant voltage (CV) control loop on the current to give the process additional robustness. In some embodiments, the peak current level 162 may be limited by the controller 42 to avoid transitioning to a spray mode. In some embodiments, the peak current level 162 may be less than 250 amps, less than 200 amps, or even smaller (e.g., between 150 and 200 amps in some embodiments). Furthermore, the peak current level 162 is limited by the controller 42 to minimize the force of the plasma on the molten pool 32 (i.e., to limit penetration and molten pool disturbance).

[0082] After a fixed amount of time in the ball-forming state 160 (e.g., less than 5 milliseconds, less than 2 milliseconds, less than 1 millisecond, or even less in some embodiments), and during the background state (e.g., interval 166) that occurs immediately after the ball-forming state 160 as the wire electrode 28 continues to retract, the controller 42 reduces the current from the peak current level 162 to a relatively low current level 168 to initiate the background state 166. Once the relatively low background current level 168 is reached, the controller 42 can switch to a constant voltage (CV) control loop to improve process robustness. In some embodiments, the background current level 168 can be limited to less than 50 amperes, or between 5 and 30 amperes, so that the plasma does not push the molten pool 32 too far away from the next short circuit, thus preventing the formation of excessively large balls 34 and the dissipation of too much heat into the molten pool 32. In some embodiments, once a relatively low background current level 168 is reached, in addition to synchronizing the welding power with the mechanical oscillation, the controller 42 may also send a command to the mechanical oscillation system 102 to restart advancing the wire electrode 28 at a positive feed rate 138. Once the background state 166 is completed, the cycle will repeat again (i.e., the next short-circuit state 154).

[0083] like Figure 9 As shown, the CSC process implemented by controller 42 may include several alternative features in some embodiments. For example, in some embodiments, Figure 9 All states 154, 158, 160, and 166 of the CSC process shown can be either constant current (CC) or constant voltage (CV). For example, all states 154, 158, 160, and 166 can be CC, but the process is not very robust. Alternatively, only one of states 154, 158, 160, and 166 can be CV to provide a certain amount of dynamic melting to help system 10 match the melting rate with the average wire feed speed. Furthermore, in some embodiments, controller 42 can use the operating average voltage to approximate the arc length and then drive the duration of the ball-forming state 160 based at least in part on the operating average voltage. In other words, if the arc length is determined by controller 42 to be shorter than desired (e.g., indicating that burn-out is not keeping up with the wire feed speed), controller 42 can change the duration of the ball-forming state 160 to melt more of the incoming wire electrode 28, thereby producing a larger ball 34 for the next ball deposition and / or increasing the oscillation frequency to deposit more balls 34 per unit time. Additionally, in some embodiments, the controller 42 may primarily implement CC power and alter the speed of the incoming welding wire electrode 28. In other words, if the controller 42 determines that the average voltage is too low (e.g., indicating a relatively low average arc length), the controller 42 may reduce the wire feed speed from the feeder 24 to increase the arc length. Doing so will tend to match the feed rate with the melting rate. However, since the dynamic control of the motor 110 of the mechanical oscillation system 102 is generally slower than that of the electrical control loop, adjusting the wire feed speed in this manner cannot achieve precise control.

[0084] In some embodiments, controller 42 may implement a conventional CV control loop, but with certain limitations imposed. Figure 10 Another set of time series is shown based on another exemplary CSC waveform implemented by controller 42, including the wire feed speed (WFS) of the welding wire electrode 28 caused by mechanical oscillation system 102 (i.e., trace 132), the voltage (V) of the electrical power generated by power supply 54 (i.e., trace 134), and the current (I) of the electrical power generated by power supply 54 (i.e., trace 136), wherein a conventional CV control loop is used under certain constraints. Specifically, as Figure 10 As shown, controller 42 can allow the CV process to operate "normally" (i.e., in a conventional manner), but limits the current during short-circuit state 154 to a current level 170 (approximately 10-100 amps) lower than the baseline current level 168 (approximately 30-150 amps), and may also limit the peak current level 162 (approximately 100-300 amps). Figure 10 As shown, in some embodiments, the above regarding Figure 9In contrast to the CC ramp 164 discussed, controller 42 can implement a constant voltage (CV) ramp 172 to drive the current from the relatively low short-circuit current level 170 to the peak current level 162 in a smoother and more asymptotic manner than the CC ramp 164. In effect, the integral component of a conventional PID control loop, which remains low during the short circuit, will be "significantly increased." Therefore, once allowed to do so, this integral component will naturally rise at the end of the short circuit. After ball 34 is formed, the voltage control loop will be satisfied, and the error will decrease, as will the current. Typically, the CV control loop is a simple way to implement a robust design with minimal effort.

[0085] As described herein, a recognized disadvantage of the relatively fixed retraction / forward and relatively fixed frequency of the mechanical oscillation system 102 is that it may be relatively difficult to synchronize with the actual disengagement of the molten pool 32 and the balls 34. Therefore, with this in mind, embodiments of the controller 42 described herein control the electrical power that generates plasma and melts the welding wire electrode 28 to compensate for the lack of precision in the mechanical oscillation system 102. Typically, the electrical power (e.g., welding power) is controlled by the mechanical process performed by the mechanical oscillation system 102. The simplest solution is to use a conventional constant current (CC) welding power source (e.g., as power source 54). In other words, if the retraction distance is large enough, the welding current can be set and maintained at a relatively fixed level. This relatively fixed current level must be high enough to melt the welding wire electrode 28 one ball 34 at a time. A relatively fixed current level would be relatively low so that it does not cause much molten pool disturbance or ejection of molten material (i.e., commonly referred to as spatter) from the molten pool 32 or from the end of the welding wire electrode 28. However, in such embodiments, the CC melting rate must match the wire feed speed. In such an embodiment, a slight “drop” in the CC response of the welding power source (e.g., power source 54) and / or voltage sensing feeder (e.g., feeder 24) will make the CC method more robust, provided that the drop in the CC control loop means a slight decrease in current as voltage increases.

[0086] In some embodiments, the process can be improved by utilizing simple dynamic changes in the welding current, such as... Figure 8-10 As shown. Figure 8-10As shown, with the goal of a relatively simple and low-cost system 10, the waveform changes implemented by the controller 42 are relatively minimal. For example, increasing the current after the wire electrode 28 has separated from the molten pool 32 helps to form the next ball 34, helps to ensure that possible molten pool oscillations do not reattach to the wire electrode 28, and helps to increase the amount of wire electrode 28 that can be deposited. Because this is a "safe" position, energy is added to the process without increasing any risk of instability. Furthermore, reducing the current when the wire electrode 28 is about to contact the molten pool 32 helps to reduce the chance of the wire electrode 28 burning out when attempting to contact the molten pool 32, and helps to reduce the chance of the wire electrode 28 and the molten ball 34 contacting the molten pool 32 and being "repelled". In addition, reducing the current when the wire electrode 28 is about to separate from the molten pool 32 helps to reduce the force of the plasma when the plasma reignites (i.e., during the arc reconstruction state 158). Reducing this force (e.g., from no plasma to plasma) reduces molten pool disturbance and helps to stabilize the process. Typically, if the arc has not yet been re-established and the retraction of the wire electrode 28 has ended or is about to end, the current must be increased by the controller 42 to force the molten column to constrict between the molten pool 32 and the wire electrode 28. In some embodiments, the controller 42 may increase the current during the short-circuit state 154 to achieve some resistance heating of the wire electrode 28. Doing so helps to add heat to the wire electrode 28 without requiring more heat to be added to the molten pool 32, thereby reducing the time required for plasma to spend and consequently reducing the heat entering the molten pool 32, which may be advantageous for, for example, the construction of small parts.

[0087] Additionally, in some embodiments, during the short-circuit state 154, the controller 42 keeps the current relatively low. After the short circuit is cleared, for a relatively short period (e.g., in some embodiments, less than 40 milliseconds, less than 5 milliseconds, less than 1 millisecond, or even less) the controller 42 can increase the current (e.g., during the ball-forming state 160) to form the ball 34. In some embodiments, the ball-forming state 160 will include a constant voltage (CV) characteristic, thus having the additional advantage of increasing or decreasing the ball-forming peak current level 162, thereby forming larger or smaller balls 34 depending on the proximity of the wire electrode 28 to the molten pool 32 (e.g., arc length). The CV characteristic helps to balance the melting rate with the average forward wire feed rate. In some embodiments, the CV characteristic can be implemented by the controller 42 by adjusting the duration or amplitude of the ball-forming state 160.

[0088] Then, after forming sphere 34, controller 42 can reduce the current to a relatively low background current level 168. Figure 8 In the illustrated embodiment, this current reduction will have a constant current (CC) characteristic. However, in Figure 9 and 10 In the illustrated embodiment, this current reduction will have a constant voltage (CV) characteristic, which will help match the average wire feed rate with the melting rate. Typically, the controller 42 will maintain a relatively low background current level 168 sufficiently low to minimize the force exerted on the molten pool 32 from the plasma when the wire electrode 28 approaches the molten pool 32, and to minimize spatter when the ball 34 contacts the molten pool 32. Additionally, the controller 42 will maintain a relatively low background current level 168 while waiting for the wire electrode 28 to retract from the molten pool 32 and for the ball 34 to remain in the molten pool 32.

[0089] In some embodiments, the controller 42 may induce a current pulse during short-circuit state 154, which will tend to increase the resistive heating of the wire electrode 28, but may also generate more spatter if the short-circuit clearing is still at a relatively high pulse current level. In some embodiments, the controller 42 may implement a "safety net" short-circuit clearing state to deal with situations where the wire electrode 28 is not fully retracted from the molten pool 32 (e.g., when the duration of short-circuit state 154 is longer than one or two full mechanical oscillation cycles of the wire electrode 28 caused by the mechanical oscillation system 102). Such a short-circuit clearing state may include completely stopping the process or implementing a relatively high current short-circuit clearing energy pulse.

[0090] To describe the operation of the system 10 described herein, a specific example will be given. Specifically, assume that the wire electrode 28 has a positive net total wire feed rate of 120 inches per minute or 2 inches per second (i.e., including forward feed and retraction), which is relatively slow for a wire feed rate, and assume that the mechanical oscillation system 102 causes the wire electrode 28 to oscillate at a substantially fixed rate of 60 oscillations per second, then the wire electrode 28 oscillates up and down 60 times every 2 inches. Therefore, typically, the wire electrode 28 should traverse 60 molten metal balls 34 every 2 inches. Thus, the wire electrode 28 is advanced such that each ball 34 will consume approximately 2 / 60 inch (i.e., approximately 0.0333 inches) of the wire electrode 28.

[0091] Furthermore, if the mechanical oscillation system 102 causes the wire electrode 28 to oscillate at a substantially fixed rate of 60 oscillations per second, and if the duration of each phase of the forward movement of the wire electrode 28 is approximately equal to the duration of each phase of the retraction of the wire electrode 28, then the duration of the forward movement and retraction phases of the wire electrode 28 is approximately 1 / 120 of a second (i.e., approximately 8.333 milliseconds). At a steady forward advance rate of 2 inches per second from the feeder 24, the wire electrode 28 moves approximately 0.01667 inches (i.e., 2 inches / second × 0.008333 seconds) while it is retracting. Typically, the wire electrode 28 must retract approximately 0.01667 inches plus the distance required to break the liquid bridge (e.g., the diameter of a single ball 34 can be estimated to be approximately 0.05 inches). Therefore, the total retraction distance of the wire electrode 28 must be at least approximately 0.05 + 0.01667 = approximately 0.06667 inches. Typically, the reduced time spent on retraction results in a smaller amount of wire electrode 28 being advanced when retraction occurs.

[0092] When the plasma reignites, it melts the welding wire electrode 28, increasing the distance the molten ball 34 must travel to reconnect with the molten pool 32. Assuming a new ball 34 has already formed, and approximately 0.0333 inches of welding wire electrode 28 has been melted to form a ball 34 with a diameter of 0.05 inches, moving forward by more than 0.1 inches or retracting almost guarantees that the molten ball 34 will reconnect or separate from the molten pool 32. In this case, the distance is twice the diameter of the ball 34 and is a relatively small travel distance.

[0093] The diameter of the ball 34, slightly larger than that of the welding wire electrode 28, is also common in other welding processes. Generally, the retraction speed should be significantly faster than the forward movement speed. Furthermore, the relatively fixed travel distance of the retraction should be sufficient to pull the welding wire electrode 28 out of the molten pool 32. Additionally, surface tension will tend to cause the molten metal to "stick" from the pool 32 to the welding wire electrode 28, so the retraction travel distance should be sufficient to overcome this surface tension.

[0094] Typically, the current flowing through a liquid conductor causes it to contract. This is known as the "pinch effect." In conventional MIG welding processes, a relatively high peak current is used to separate the weld wire from the molten pool. However, this relatively high current also reignites the plasma, disturbing the molten pool with relatively strong force and increasing a certain degree of variability in the process. Ideally, the plasma is reignited at a relatively low current, resulting in minimal disturbance.

[0095] In the embodiments described herein, the wire electrode 28 is separated from the molten pool 32 by retracting it. If the wire electrode 28 is not completely separated, more current can be added to drive the electric clamping. Since retraction may narrow the liquid column, the required current is still less than that without retraction. For relatively small diameter wires, the liquid ball 34 (and subsequently the liquid column between the end of the wire electrode 28 and the molten pool 32) will have a smaller diameter, and a shorter retraction can be used. Speed ​​is not necessarily a critical performance requirement for the low-cost system 10. Furthermore, a smaller diameter wire electrode 28 will produce a smaller ball and a narrower molten pool 32, which will provide greater resolution for the finished part. Typically, the speed of part manufacturing can be sacrificed for resolution, accuracy, and reduced weld penetration.

[0096] Certain alternatives can be used for the system 10 described herein. For example, instead of using the CSC process described herein, in some embodiments, the MIG welding process can be implemented by the controller 42 and the power supply 54. In such embodiments, the mechanical retraction caused by the mechanical oscillation system 102 ensures better startup and fewer problems. Furthermore, in other embodiments, the RMD welding process can also be implemented by the controller 42 and the power supply 54. In such embodiments, the RMD process can be optimized by the controller 42 for a specific application. Additionally, in other embodiments, a modified submerged arc welding (SAW) process can be implemented by the controller 42 and the power supply 54. In such embodiments, the flux will allow the finished parts to have different metallurgical properties. In all embodiments described herein, different alloys of the welding wire electrode 28, especially cored wire, can be used to obtain unique metallurgical properties in the finished parts.

[0097] Typically, the embodiments described herein aim to enhance the separation of the balls 34 using a relatively low-cost mechanical oscillation system 102. In some embodiments, the mechanical oscillation system 102 can send shock waves downward along the welding wire electrode 28, much like a pneumatic drill. This vibration in the liquid column can cause the liquid column to begin to contract. Once this contraction begins, a pinching effect will begin if there is sufficient current.

[0098] In some embodiments, the additive bonding process for forming 3D parts places a weld bead on top of a previous weld bead to form the part. If the substrate is fused to the first weld bead, then the substrate must be used. In such embodiments, conductive and cooling plates, such as water-cooled copper blocks, can be used. This block is not fused to the weld bead. This allows for more flexible part formation (specifically, the first and second layers).

[0099] Furthermore, the embodiments described herein enable the implementation of a relatively low-cost system 10, which includes a mechanical oscillation system 102 having a relatively fixed travel distance and a relatively limited range of oscillation frequencies to cause the welding wire electrode 28 to oscillate between forward movement and retraction. The relatively lack of precision in the mechanical oscillation system 102, which contributes to reducing the cost of system 10, is compensated by the controller 42 executing the CSC process described herein via power supply 54.

[0100] The embodiments described herein can also facilitate better arc ignition. Arc ignition is a long-standing problem in arc welding using consumable electrodes, and its economics are amplified in short-seam welding, such as automotive seats. Typically, the welding wire is fed at a slow feed rate (called a break-in speed) until a short circuit occurs. Thereafter, a surge of current is output from the welding power source to ignite the arc or melt the short circuit like a fuse, hopefully resulting in arc ignition. However, depending on the initial contact conditions between the welding wire and the workpiece, fuse explosion and arc ignition can be uneven. If the contact resistance is low, for example when the wire tip is not sharp, the wire stubs out and the entire wire extending from the contact end can break like a flying baton, or the wire can bend like a noodle when heated. Remedies do exist for better arc ignition to achieve a moderate arc ignition, but these come with drawbacks. For example, slower break-in speeds waste robot cycle time; wire retraction initiation requires an expensive motorized torch, and wire sharpening pulses at the arc tip can produce pitting defects.

[0101] The system 10 described herein can be used to facilitate initial wire-workpiece contact (or "scratch starting") at least in part due to the oscillation of the wire electrode 28 generated by the mechanical oscillation system 102. Typically, the oscillation of the wire electrode 28 can be manipulated to create slight contact between the wire electrode 28 and the workpieces 16, 18, thereby increasing the contact resistance R and the I at the end of the wire electrode 28 contacting the workpieces 16, 18. 2 The resistance R (i.e., the square of the current (I) multiplied by the resistance (R)) increases with heating. As the resistance R increases, the same current I can produce an increased heating effect to ignite the electric arc.

[0102] Figure 11This is a flowchart describing an arc initiation process 174 that may be implemented by the system 10 described herein in some embodiments. The arc initiation process 174 may begin when the controller 42 has received an arc initiation command (e.g., in manual welding, the operator is pulling the trigger 80 of the welding torch 20, or, for example, in robotic welding, the robot cycle start button is being pushed) (box 176). Once the controller 42 has received the arc initiation command, the controller 42 may send a command to the mechanical oscillation system 102 to initiate oscillation of the welding wire electrode 28 (box 178). Additionally, the controller 42 may send a command to the feeder 24 to begin feeding the welding wire electrode 28 to the welding torch 20 (box 180). One or more sensors 72 may then be used to sense whether an arc has been established between the welding wire electrode 28 and the workpieces 16, 18 (box 182). For example, in some embodiments, the sensor 72 may include a voltage sensing circuitry and / or a current sensing circuitry, which may be used to detect when the voltage and / or current exceeds a predetermined threshold, such as 14 volts. Once it is determined that the conditions for arc establishment have occurred, the controller 42 can send a command to the mechanical oscillation system 102 to stop the oscillation of the welding wire electrode 28 (box 184). This reduces the duty cycle requirements of the motor 110 of the mechanical oscillation system 102, thereby reducing the cost and weight requirements of the mechanical oscillation system 102. Then, the controller 42 can send a command to the feeder 24 to ramp up the feed rate of the welding wire electrode 28 to a desired wire feed speed (box 186), which can be set via the operator interface 78.

[0103] refer to Figure 11 The described arc initiation process 174 (which can be implemented by the system 10 described herein) offers several advantages over conventional arc initiation methods. For example, arc initiation process 174 provides more reliable arc initiation than conventional methods, resulting in less downtime and less spatter. These two advantages are particularly important in short weld seams and multiple arc initiation applications. Furthermore, the cost of arc initiation process 174 is relatively lower than conventional methods, at least in part due to the implementation of the relatively low-cost mechanical oscillation system 102. Additionally, arc initiation process 174 reduces cycle time, allowing for increased break-in speeds while still producing reliable arc initiation. Furthermore, arc initiation process 174 reduces electromagnetic interference (EMI) and electromagnetic field (EMF), requiring relatively low arc currents while still producing reliable arc initiation. Additionally, arc initiation process 174 increases contact end life due to less electro-erosion, which could otherwise result from the relatively low arc current surge during arc initiation. Furthermore, references can be made to the system 10 described herein. Figure 11The described arc initiation process 174 can provide arc-related advantages in a number of applications, including but not limited to gas metal arc welding (GMAW), including MIG welding; SAW; wire brazing; surfacing, including cladding and / or surface hardening; multi-wire GMAW / SAW; GMAW-laser hybrid welding; and the like.

[0104] While only certain features of this disclosure have been illustrated and described herein, many modifications and variations will occur to those skilled in the art. Therefore, it should be understood that the appended claims are intended to cover all such modifications and variations falling within the true spirit of this disclosure.

Claims

1. A system comprising: A welding tool configured to receive welding wire from a wire feeder, receive welding power from a power source, and supply the welding wire to the workpiece during the welding process; A mechanical oscillation system configured to mechanically oscillate a structural component toward and away from the workpiece, wherein the structural component is external to the wire feeder and the power supply; as well as A control circuit system configured to control the welding power based on feedback related to the welding process so that the melting rate of the welding wire matches the average wire feed speed, thereby compensating for the wide range of oscillation frequencies and oscillation travel distances of the mechanical oscillation system. The control circuitry is configured to control the welding power based at least in part on feedback related to the timing of a short circuit occurring between the welding wire and the workpiece during the welding process; as well as The control circuit system is configured to maintain the welding power current level substantially constant for a predetermined time period after the short circuit ends, before increasing the welding power current level.

2. The system of claim 1, wherein the structural component is at least partially disposed within the welding tool.

3. The system of claim 1, wherein the welding tool comprises the mechanical oscillation system and the structural component.

4. The system according to claim 1, wherein the welding tool is a handheld welding tool.

5. The system according to claim 1, wherein the welding tool is a robotic welding tool.

6. The system of claim 1, wherein the structural component comprises a bushing.

7. The system of claim 1, wherein the welding process comprises a metal polar inert gas (MIG) welding process.

8. The system of claim 1, wherein the welding wire extends through the structural component.

9. The system of claim 1, wherein the mechanical oscillation of the structural component has a substantially fixed travel distance.

10. The system of claim 1, wherein the mechanical oscillation of the structural component has a substantially fixed frequency.

11. The system of claim 1, wherein the mechanical oscillation system comprises a motor and a mechanical linkage assembly coupled to the motor, wherein the mechanical linkage assembly is fixedly attached to the structural component.

12. The system of claim 11, wherein the welding tool includes a bushing extending into the structural member, the welding wire extending through the bushing, and the structural member being directly coupled to the bushing.

13. The system of claim 11, wherein the mechanical linkage assembly includes a cam coupled to the motor and a piston coupled to the cam, wherein the piston is fixedly attached to the structural component.

14. The system according to claim 1, The mechanical oscillation system is configured to reverse the movement of the welding wire during controlled short-circuit welding to separate the molten ball from the welding wire, wherein the controlled short-circuit welding process includes RMD. TM and controlled short circuit (CSC) welding process; and The mechanical oscillation system is configured to advance and retract the welding wire in a controlled short circuit (CSC) system without requiring a motor to change direction.

15. The system of claim 1, wherein the control circuitry is configured to determine when the short circuit occurs based at least in part on feedback received from a sensor detecting the voltage level of the welding power.

16. The system of claim 1, wherein the predetermined time period is a time period between 100 and 300 milliseconds.

17. The system of claim 1, wherein the control circuitry is configured to increase the current level of the welding power to a peak current level after the short circuit ends.

18. The system of claim 17, wherein the control circuitry is configured to use a constant current (CC) ramp to increase the current level to the peak current level.

19. The system of claim 17, wherein the control circuitry is configured to determine the rate of increase of the current level to the peak current level based at least in part on the diameter of the welding wire, the average wire feed speed of the welding wire, or a combination thereof.

20. The system of claim 17, wherein the control circuitry is configured to gradually increase the current level to the peak current level.

21. The system of claim 17, wherein the peak current level is less than 250 amperes.

22. The system of claim 17, wherein the control circuitry is configured to reduce the current level from the peak current level to a baseline current level.

23. The system of claim 22, wherein the background current level is less than 50 amperes.

24. The system of claim 22, wherein the control circuitry is configured to maintain the current level at the peak current level for a fixed amount of time before reducing the current level to the baseline current level.

25. The system of claim 22, wherein the control circuitry is configured to maintain a substantially constant voltage level of the welding power when the background current level is reached.

26. The system of claim 1, wherein the control circuitry is configured to control the welding power based at least in part on feedback relating to the timing of the welding arc occurring between the welding wire and the workpiece during the welding process.

27. The system of claim 1, wherein the control circuitry is configured to control the welding power based at least in part on feedback relating to mechanical oscillations of the structural component.

28. The system of claim 1, wherein the control circuitry is configured to control the mechanical oscillations of the structural components.

29. The system of claim 1, wherein the control circuitry is configured to switch between a constant current (CC) operating mode and a constant voltage (CV) operating mode, at least in part based on the feedback associated with the welding process, to match the melting rate of the welding wire with the average wire feed rate of the welding wire.

30. The system according to claim 29, wherein, The constant voltage (CV) operating mode provides a certain amount of dynamic power to match the melting rate of the welding wire with the average wire feed speed.

31. A system comprising: A welding tool configured to receive welding wire and supply the welding wire to a workpiece, wherein the welding tool includes a mechanical oscillation system configured to cause structural components of the welding tool to mechanically oscillate toward and away from the workpiece; as well as A control circuit system configured to control welding power based on feedback related to the welding process to match the melting rate of the welding wire with the average wire feed speed of the welding wire, thereby compensating for the wide range of oscillation frequencies and oscillation travel distances of the mechanical oscillation system, wherein the control circuit system is configured to receive an arc initiation command during the arc initiation process, control the mechanical oscillation system to initiate oscillation of the structural component, control the wire feeder to start feeding the welding wire, determine, at least in part, based on feedback received from sensors, whether an arc has been ignited between the welding wire and the workpiece, control the mechanical oscillation system to stop the oscillation of the structural component once the arc is determined to be established, and control the wire feeder to increase the wire feed speed of the welding wire to a desired wire feed speed; The control circuitry is configured to control the welding power based at least in part on feedback related to the timing of a short circuit occurring between the welding wire and the workpiece during the welding process; The control circuit system is configured to maintain a substantially constant current level of the welding power for a predetermined time period after the short circuit ends, before increasing the current level of the welding power.

32. The system of claim 31, wherein the sensor comprises a voltage sensing circuit system, a current sensing circuit system, or a combination thereof, the voltage sensing circuit system being configured to detect the voltage level of welding power supplied from a power source to the welding tool, and the current sensing circuit system being configured to detect the current level of the welding power.

33. The system of claim 31, wherein the welding wire extends through the structural component.

34. The system of claim 31, wherein the mechanical oscillation of the structural component has a substantially fixed travel distance.

35. The system of claim 31, wherein the mechanical oscillation of the structural component has a substantially fixed frequency.

36. The system of claim 31, wherein the mechanical oscillation system comprises a motor and a mechanical linkage assembly coupled to the motor, wherein the mechanical linkage assembly is fixedly attached to the structural component; The mechanical oscillation system is configured to reverse the movement of the welding wire during controlled short-circuit welding to separate the molten ball from the welding wire, wherein the controlled short-circuit welding process includes RMD. TM Controlled short circuit (CSC) welding process; and The mechanical oscillation system is configured to advance and retract the welding wire in a controlled short circuit (CSC) system without requiring the motor to change direction.

37. The system of claim 36, wherein the mechanical linkage assembly includes a cam coupled to the motor and a piston coupled to the cam, wherein the piston is fixedly attached to the structural component.

38. The system of claim 31, wherein the welding tool includes a bushing extending into the structural member, the welding wire extending through the bushing, and the structural member being directly coupled to the bushing.

39. The system according to claim 31, wherein, The mechanical oscillation system is configured to cause structural components of the welding tool to mechanically oscillate toward and away from the workpiece to generate oscillations in the welding wire, and The system is at least partially based on the oscillation of the welding wire generated by the mechanical oscillation system to generate an electric arc by creating contact between the welding wire and the workpiece.

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