Consumable electrode plasma multifunctional welding gun, welding system and method

Abstract

The invention discloses a consumable electrode plasma multifunctional welding gun, a welding system and a welding method, and belongs to the technical field of advanced welding and additive manufacturing. The welding gun is of a coaxial multi-layer integrated structure and is sequentially provided with a welding wire channel, a shielding gas channel, a water-cooling inner plasma contact tube, a hollow tungsten electrode, a plasma gas channel, a water-cooling outer plasma contact tube of an integrated powder feeding channel and an outer shielding gas channel from inside to outside. Coaxial conveying of shielding gas, plasma gas, metal wires and metal powder is achieved, and highly-compressed composite electric arcs can be generated. By adjusting the polarity of the power source, the material conveying mode and the technological parameters, the multiple functions of large-fusion-depth welding, efficient cladding, wire or wire powder collaborative additive manufacturing and high-precision repairing can be achieved through one gun, the problems that in the prior art, the function is single, efficiency is insufficient or cost is high are solved, and the advantages of being high in integration degree, powerful in function and flexible in application are achieved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of advanced welding and additive manufacturing technology, and particularly relates to a coaxial composite welding torch integrating the functions of gas metal arc welding, plasma arc welding and powder addition, a welding system and a corresponding welding method, and in particular to a gas metal arc plasma multifunctional welding torch, a welding system and a method. BACKGROUND

[0002] With the development of modern industry and the increasing demand for welding technology, traditional welding methods are increasingly showing their limitations: gas metal arc welding has relatively low arc energy density, shallow penetration, low efficiency when welding thick plates, and large heat input leading to severe deformation. Tungsten inert gas welding has higher energy density than MIG, but has low deposition efficiency and slow welding speed. Plasma arc welding has high energy density, a straight arc column, strong directionality and large penetration, but usually has low deposition efficiency. Laser / arc composite welding combines the advantages of laser and arc, but the system cost is extremely high and maintenance is complex. In addition, existing wire or powder feeding additive manufacturing equipment has single function and is difficult to switch between efficient cladding and high-precision welding. Therefore, there is an urgent need for a solution with high integration, relatively low cost, diverse functions and the ability to significantly improve welding efficiency and quality.

[0003] The patent CN202111581578.7 discloses a plasma-arc composite welding method, the core process scheme of which is: using a coaxial tubular tungsten electrode and a consumable electrode, using two power sources to generate a first plasma arc and a second MIG arc, and applying the two arcs to the common molten pool, and feeding at least one electrically neutral filler wire into the pool to achieve deep penetration welding or low dilution rate surfacing. The authorized patent has the following disadvantages: first, the technical solution is highly dependent on specific process methods and parameter matching, although the composite plasma generator structure is described, the core mechanical structure of the welding torch for implementing the method is not protected innovatively. The welding torch may only be an adaptation of existing devices, and the structural rigidity and functional expandability are limited when dealing with more complex process requirements. Second, the function is relatively simple, mainly focusing on welding and surfacing, although additive manufacturing is mentioned, but there is a lack of systematic hardware support for synchronous powder addition, path planning and shape control of materials in three-dimensional directional energy deposition additive manufacturing. Third, the technical effect is mainly achieved through process parameter optimization, and there is no special design for hardware level heat management redundancy to ensure long-term stability and large current composite arc work.

[0004] The patent CN201410691347.5 discloses a kind of plasma-melted electrode arc dynamic composite welding device and method.The core technical route is to adopt discrete double welding gun combination, and introduce third TIG power supply and pulse coordination controller, by precise control, the current peak of plasma arc and MIG arc is alternately worked in time, to eliminate electromagnetic interference, reduce tungsten electrode burn loss.The shortcomings of the authorized patent are: first, the system composition is extremely complex, needs three independent power supplies, multiple current detection devices and high-precision synchronous controller, leading to high equipment cost, low system integration, parameter debugging and maintenance difficulty.Second, the adopted side-shaft type double-gun structure leads to the separation of two heat sources in space, and the energy concentration degree and coupling efficiency are lower than that of coaxial structure, it is difficult to form a single composite arc with extremely high energy density, and there is a physical bottleneck in realizing limit penetration or high-efficiency deposition.Third, the "dynamic time-sharing" working mode means that only one arc is at peak power at any time, which is essentially a trade-off between continuous energy output per unit time and stability, which is not the optimal solution for additive manufacturing processes that pursue extreme efficiency or continuous material addition. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a melt electrode plasma multifunctional welding torch, welding system and method.

[0006] The purpose of the present application is achieved by the following technical solution: a melt electrode plasma multifunctional welding torch, the welding torch comprises, from inside to outside, a center conductive nozzle (melted electrode wire feeding channel), a melt electrode shielding gas channel, an inner plasma conductive nozzle, a plasma gas channel, an outer plasma conductive nozzle, an outer shielding gas channel and a shielding nozzle. The center conductive nozzle is located at the center of the welding torch and is used for coaxial delivery of the melt electrode wire, and is connected to the power supply as a consumable electrode. The conductive tube is connected to the positive electrode (DC+) or negative electrode (DC-) of the power supply (depending on the process requirements). The melt electrode shielding gas channel surrounds the center conductive nozzle and is used for delivering high-purity, high-pressure shielding gas. The inner plasma conductive nozzle surrounds the melt electrode shielding gas channel and is internally provided with a hollow tungsten electrode and an inner plasma conductive nozzle water cooling channel. The inner plasma conductive nozzle water cooling channel is used for connecting the hollow tungsten electrode, conducting electricity and cooling the hollow tungsten electrode. The hollow tungsten electrode serves as an electrode and is used for generating a plasma arc. The plasma gas channel surrounds the inner plasma conductive nozzle and is used for delivering high-purity, high-pressure plasma gas (such as argon). The outer plasma conductive nozzle surrounds the plasma gas channel and is internally provided with an outer plasma conductive nozzle water cooling channel and a powder feeding channel, which are used for compressing the plasma arc and delivering metal or alloy powder. The outer protective gas channel surrounds the outer plasma conductive nozzle and is used for conveying protective gas (such as Ar, CO2 or mixed gas) to form a gas cover covering the entire arc, molten pool and high-temperature metal, so as to prevent air from entering to cause oxidation and nitrogen; The protective nozzle is located at the outermost layer of the welding torch and is internally provided with a protective nozzle water cooling channel. The welding torch integrates shielded metal arc welding, plasma arc welding and powder adding functions, and realizes synchronous conveying of protective gas, plasma gas, metal wire and metal powder through a coaxial structure and forms a highly compressed composite arc.

[0007] Further, the center conductive nozzle is connected to a consumable electrode power supply, the hollow tungsten electrode is connected to a plasma arc power supply, and the polarity of the plasma arc power supply and the consumable electrode power supply is independently adjustable and can be configured as direct current positive connection (DCEN) or direct current reverse connection (DCEP).

[0008] Further, the powder feeding channel is used for coaxially conveying metal or alloy powder to the arc area and the molten pool through a carrier gas, and the powder feeding channel is integrated in the multi-layer structure of the outer plasma conductive nozzle.

[0009] Further, the inner plasma conductive nozzle water cooling channel, the outer plasma conductive nozzle water cooling channel and the protective nozzle water cooling channel are all connected to an external cooling system for forced water cooling to maintain the thermal stability of the welding torch under large current.

[0010] The application also provides a consumable electrode plasma multifunctional welding system, comprising: a multifunctional welding torch; a plasma arc power supply connected to the hollow tungsten electrode for generating a sustaining arc and a main arc; a consumable electrode power supply connected to the center conductive nozzle for supplying power to the welding wire; a wire feeding system for controlling the welding wire conveying speed and stability; a powder feeding system for controlling the conveying rate of metal or alloy powder; a gas supply system for independently controlling the flow and pressure of plasma gas, protective gas and powder carrying gas; a cooling system for providing circulating cooling for the water cooling channels of the welding torch; a motion execution mechanism for controlling the motion trajectory of the welding torch relative to the workpiece; a central control system for cooperatively controlling the plasma arc power supply, the consumable electrode power supply, the wire feeding system, the powder feeding system, the gas supply system, the cooling system and the motion execution mechanism, and for coordinately controlling the power output, the wire / powder feeding speed, the gas flow and the mechanical motion to realize automatic welding or additive manufacturing.

[0011] Further, the plasma arc power supply is configured as direct current positive connection, the consumable electrode power supply is configured as direct current reverse connection, and the two power supplies are independently adjustable or controlled in parallel.

[0012] Further, the wire feeding system adopts a servo motor to drive a wire feeding mechanism, the powder feeding system includes a powder tank and one of a Venturi powder feeder and a screw powder feeder.

[0013] Further, the motion execution mechanism is a six-axis welding robot, a numerical control machine tool or a three-axis workbench.

[0014] The application also provides a consumable electrode plasma multifunctional welding method, including the following steps: Starting the gas supply system to start the delivery of protective gas and plasma gas; Igniting the plasma arc, first forming a non-transferred arc, and then transferring to the workpiece to form a stable transferred plasma arc; Starting the wire feeding system and the consumable electrode power supply to make the welding wire enter the plasma arc area, ignite the MIG arc, and form a composite arc of the plasma arc and the MIG arc; Moving the welding torch through the motion execution mechanism to perform welding or additive manufacturing; When the arc is extinguished, first stop the wire feeding and the consumable electrode power supply, then attenuate the plasma arc current, and delay the closing of the protective gas until the molten pool cools.

[0015] Further, the welding or additive manufacturing process includes starting the powder feeding system to coaxially feed metal or alloy powder into the arc area through the carrier gas to form a weld or cladding layer with the welding wire.

[0016] The welding torch of the application has the advantages that the welding torch is highly integrated, the consumable electrode wire is used as the cathode or anode of the plasma arc, the protective gas, the plasma gas, the metal wire and the metal powder are coaxially delivered, a highly compressed and energy concentrated composite arc is generated, multiple materials can be added synchronously, a multifunctional welding torch integrating multiple welding methods and additive manufacturing is realized, the components of the welding torch can be water-cooled to ensure the process stability during use, the plasma welding, MIG welding, plasma MIG composite welding, cladding, wire additive manufacturing and wire-powder collaborative additive manufacturing can be realized by one welding torch, and the application range is extremely wide.

[0017] Compared with the prior art, the core contribution of the present application is the first coaxial multi-layer welding gun mechanical structure, which provides a standardized, modular and highly reliable hardware platform for realizing the plasma-MIG hybrid technology by integrating the welding wire channel, the protective gas channel, the water-cooled inner / outer plasma conducting nozzle, the plasma gas channel, the integrated powder feeding channel and the outer protective gas channel from the inside to the outside. The present application not only covers the hybrid arc function of the previous patent, but also solves the problem of thermal stability under high current through the integrated water cooling system, and expands the wire-powder collaborative additive manufacturing capability through the coaxial integrated powder feeding channel. Therefore, the present application provides strong support for the hybrid process from the hardware root, realizes the upgrade from "specific method" to "general multifunctional platform", has a wider application range and better process stability.

[0018] The present application discards the complex multi-power timing control strategy and returns to the physical root of the coaxial structure design. By taking the consumable electrode as one of the electrodes of the plasma arc and highly integrating all functional channels in a single coaxial welding gun, the present application can form a highly compressed and continuously stable hybrid arc in space. This method reduces the electromagnetic interference path caused by spatial separation of the arc from the source, and the multi-layer water cooling design directly protects the hollow tungsten electrode and other key components, also achieving the purpose of prolonging the service life. Therefore, the present application provides a hardware solution that is more concise in system, more concentrated in energy and more suitable for continuous and efficient manufacturing, avoiding the inherent contradiction between control complexity and continuous power output of the dynamic time-sharing system. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0020] Figure 1 A cross-sectional view of the multifunctional welding gun provided by the present application is shown in the figure. In the figure, the numbers represent: 1, center conducting nozzle; 2, welding wire; 3, inner plasma conducting nozzle; 4, hollow tungsten electrode; 5, outer plasma conducting nozzle; 6, consumable electrode protective gas channel; 7, plasma gas channel; 8, protective gas channel; 9, inner plasma conducting nozzle water cooling channel; 10, outer plasma conducting nozzle water cooling channel; 11, powder feeding channel; 12, protective nozzle; 13, protective nozzle water cooling channel. DETAILED DESCRIPTION

[0021] In order to make the personnel in the art better understand the technical solutions in the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art shall fall within the scope of protection of the present application.

[0022] In the description of the present application, the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom" and the like is the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present application and does not require the present application to be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. The terms "connected", "connected", "provided" used in the present application should be understood broadly, for example, can be fixed connection, can also be detachable connection; can be directly connected, can also be indirectly connected through intermediate parts; can be wired electrical connection, wireless electrical connection, or wireless communication signal connection, and those of ordinary skill in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0023] As shown in Figure 1 The present application provides a multi-functional welding torch with a consumable electrode, which comprises, from inside to outside, a center electrode nozzle 1, a consumable electrode shielding gas channel 6, an inner plasma electrode nozzle 3, a plasma gas channel 7, an outer plasma electrode nozzle 5, an outer shielding gas channel 8, and a shielding nozzle 12.

[0024] The center electrode nozzle 1 is used to coaxially transport a consumable electrode wire 2 and is connected to a power source as a consumable electrode.

[0025] The consumable electrode shielding gas channel 6 surrounds the center electrode nozzle 1 and is used to transport shielding gas.

[0026] The inner plasma electrode nozzle 3 surrounds the consumable electrode shielding gas channel 6 and is internally provided with a hollow tungsten electrode 4 and an inner plasma electrode water cooling channel 9.

[0027] The plasma gas channel 7 surrounds the inner plasma electrode nozzle 3 and is used to transport plasma gas.

[0028] The outer plasma electrode nozzle 5 surrounds the plasma gas channel 7 and is internally provided with an outer plasma electrode water cooling channel 10 and a powder feeding channel 11.

[0029] The outer shielding gas channel 8 surrounds the outer plasma electrode nozzle 5.

[0030] The protective nozzle 12 is located at the outermost layer of the welding torch, and is internally provided with a protective nozzle water cooling channel 13.

[0031] The welding torch integrates shielded metal arc welding, plasma arc welding and powder adding functions, and realizes synchronous delivery of protective gas, plasma gas, metal wire and metal powder through a coaxial structure, and forms a highly compressed composite arc.

[0032] Preferably, the center conducting nozzle 1 is connected to a consumable electrode power source, the hollow tungsten electrode 4 is connected to a plasma arc power source, and the polarity of the plasma arc power source and the consumable electrode power source is independently adjustable, and can be configured as direct current positive connection (DCEN) or direct current reverse connection (DCEP).

[0033] Preferably, the powder feeding channel 11 is used for coaxially delivering metal or alloy powder to the arc area and the molten pool through carrier gas, and the powder feeding channel 11 is integrated in the multi-layer structure of the outer plasma conducting nozzle 5.

[0034] Preferably, the inner plasma conducting nozzle water cooling channel 9, the outer plasma conducting nozzle water cooling channel 10 and the protective nozzle water cooling channel 13 are all connected to an external cooling system for forced water cooling, so as to maintain the thermal stability of the welding torch under large current.

[0035] The embodiment of the present application also provides a consumable electrode plasma multifunctional welding system, which comprises: The multifunctional welding torch in any of the embodiments.

[0036] A plasma arc power source connected to the hollow tungsten electrode 4 for generating a sustaining arc and a main arc.

[0037] A consumable electrode power source connected to the center conducting nozzle 1 for supplying power to the welding wire 2.

[0038] Preferably, the plasma arc power source is configured as direct current positive connection, the consumable electrode power source is configured as direct current reverse connection, and the two power sources are independently adjustable or parallelly controlled.

[0039] A wire feeding system for controlling the wire delivery speed and stability.

[0040] A powder feeding system for controlling the delivery rate of metal or alloy powder.

[0041] Preferably, the wire feeding system adopts a servo motor to drive a wire feeding mechanism, and the powder feeding system comprises a powder tank and one of a Venturi powder feeder and a screw powder feeder.

[0042] A gas supply system for independently controlling the flow and pressure of plasma gas, protective gas and powder carrying gas.

[0043] A cooling system for providing circulating cooling for the water cooling channels of the welding torch.

[0044] Motion execution mechanism for controlling the motion trajectory of the welding torch relative to the workpiece, which is a six-axis welding robot, a numerical control machine tool, or a three-axis worktable.

[0045] Central control system for coordinated control of the plasma arc power source, the consumable electrode power source, the wire feeding system, the powder feeding system, the gas supply system, the cooling system, and the motion execution mechanism to achieve automatic welding or additive manufacturing.

[0046] Example 1: Large penetration efficient welding mode (plasma arc as the main, welding wire as the auxiliary) This mode is suitable for butt and fillet welds of medium-thick plates, and pursues high penetration and high welding speed.

[0047] 1. System configuration and connection Welding torch: use the coaxial multifunctional welding torch described in the invention.

[0048] Power connection: Plasma arc power source: use direct current positive connection (DCEN), that is, the hollow tungsten electrode (negative electrode) is connected to the negative terminal of the power source, and the workpiece (positive electrode) is connected to the positive terminal of the power source. This connection method is beneficial to the workpiece to obtain higher energy input and form a deep penetration weld. Consumable electrode power source: use direct current reverse connection (DCEP), that is, the center electrode (positive electrode) is connected to the positive terminal of the power source, and the workpiece (negative electrode) shares the ground wire with the plasma power source. At this time, the welding wire acts as an anode, and the arc heat is more concentrated at the end of the welding wire, which is beneficial to its melting and forms a higher deposition efficiency. Note: The two power sources need to be independently adjustable, but share the ground wire. It is recommended to use a multifunctional digital power source with coordinated control function.

[0049] Wire feeding system: choose φ1.0mm or φ1.2mm solid steel welding wire (such as ER70S-6). The wire feeder is set to "push" or "push-pull" to ensure stable long-distance wire feeding.

[0050] Powder feeding system: In this mode, the powder feeding system is turned off.

[0051] Gas supply system: Plasma gas: pure argon (Ar), flow rate 8-15 L / min. Generate a vortex through a vortex ring to compress the arc. Shielding gas: Ar + 2-5% CO2 or Ar + 5-10% O2 mixed gas, flow rate 18-25 L / min, to form an effective gas protection layer.

[0052] Cooling system: turn on the circulating water cooler to ensure water pressure ≥0.4MPa and flow rate ≥4L / min to fully cool all water cooling channels.

[0053] Motion execution mechanism: install the welding torch on the six-axis welding robot arm.

[0054] 2. Welding process flow Step 1: Arc initiation The welding torch is aimed at the starting point of the weld, 3-5 mm from the workpiece surface. First, the shielding gas and plasma gas are turned on. The plasma arc power source first outputs a high-frequency high-voltage pulse or a small current (usually 5-30 A) non-transferred arc to ignite between the hollow tungsten electrode and the center conducting nozzle / nozzle as a guide. Then, the power source quickly transfers the arc to the workpiece and the hollow tungsten electrode, forming a stable transferred plasma arc (main arc).

[0055] Step 2: Wire feeding and welding After the main plasma arc is stably established, delay for 0.1-0.5 seconds, start the wire feeding system and the consumable electrode power source. The welding wire is fed from the center channel into the plasma arc column. Since the welding wire is connected to the positive electrode, it will attract the anode spot of the plasma arc, thereby igniting the MIG arc between the welding wire and the workpiece. At this time, a composite arc coexisting with the plasma arc and the MIG arc is formed. The plasma arc serves as the main heat source to penetrate the base metal and form a deep melt; the MIG arc serves as an auxiliary heat source to further heat the welding wire and the molten pool, and adds filler metal. The robot moves the welding torch according to the preset trajectory and speed.

[0056] Step 3: Arc termination When welding to the end point, first stop the wire feeding and the consumable electrode power source. Then, the welding torch stays at the current position for a short time (0.5-1.0 seconds), and the plasma arc current decays to zero according to the preset slope before being turned off to fill the crater. Delay the closing of the shielding gas (about 5-10 seconds) until the molten pool solidification area cools below 400°C to prevent oxidation.

[0057] Example 2: High-speed high-deposition additive manufacturing mode (welding wire as the main, plasma arc as the auxiliary) This mode is suitable for large-area, high-efficiency metal 3D printing or surface cladding.

[0058] 1. System configuration and connection Welding torch: use the coaxial multifunctional welding torch described in the present invention.

[0059] Power connection: the consumable electrode power source uses direct current reverse connection (DCEP) as the main heat source. The current is large, for example, 250-400 A. The plasma arc power source uses direct current positive connection (DCEN), but the current is set lower (for example, 50-120 A), mainly to stabilize the MIG arc, preheat the powder / base material, and improve the fluidity of the molten pool.

[0060] Wire feeding system: choose φ1.2 mm or φ1.6 mm additive special alloy welding wire (such as 316L stainless steel, Inconel 625, etc.).

[0061] Powder feeding system: on. Select the same or different alloy powder as the welding wire composition (such as Co-Cr-W alloy powder), and send it into the powder feeding channel outside the welding torch through the carrier gas (pure Ar). The powder flow is coaxially focused at the root of the arc.

[0062] Gas supply system: plasma gas: pure Ar, flow rate 5-10 L / min. Powder carrying gas: pure Ar, flow rate 3-8 L / min. Shielding gas uses high-purity Ar or a mixed gas customized according to the material properties, flow rate 20-30 L / min, providing all-round protection for the additive process.

[0063] Cooling system: turn on the circulating water cooler, ensure water pressure ≥0.4 MPa, flow rate ≥4 L / min, and fully cool all water-cooled channels.

[0064] Motion execution mechanism: the welding torch is installed on a CNC machine tool or a large robot for layer-by-layer scanning motion.

[0065] 2. Welding process Step one: starting the arc The welding torch is aimed at the starting point of the weld, 3-5 mm away from the workpiece surface. First, turn on the shielding gas and the plasma gas. The plasma arc power source first outputs a high-frequency high-voltage pulse or a small current (usually 5-30 A) non-transferred arc between the hollow tungsten electrode and the center conducting nozzle / nozzle, which serves as a guide. Then, the power source quickly transfers the arc to the workpiece and the hollow tungsten electrode, forming a stable transferred plasma arc (main arc).

[0066] Step two: wire feeding and welding After the main plasma arc is established, delay for 0.1-0.5 seconds, start the wire feeding system and the consumable electrode power source. The welding wire is fed from the center channel into the plasma arc column. Since the welding wire is connected to the positive electrode, it will attract the anode spot of the plasma arc, thereby igniting the MIG arc between the welding wire and the workpiece. At this time, a composite arc coexists with the plasma arc and adds filler metal. The robot moves the welding torch according to the preset trajectory and speed.

[0067] Step three: composite processing The welding wire is largely melted by the MIG arc to form the main deposited metal. At the same time, the alloy powder is transported by the carrier gas, passes through the outer plasma arc area, is preheated and partially melted, and falls into the molten pool. The addition of powder can flexibly adjust the chemical composition and performance of the cladding layer. The coaxial plasma arc surrounds the MIG arc outside, producing a "pinch" effect on the arc, making it more stable and concentrated, avoiding the large swing of conventional MIG welding, and improving the forming accuracy.

[0068] The control system controls the welding torch to perform plane scanning and layer-by-layer lifting according to the three-dimensional model, completing the manufacturing of the solid component.

[0069] Step four: Arc closing At the end of each layer, stop powder feeding, wire feeding and power supply in sequence, and keep gas protection.

[0070] Example 3: High precision / repair mode (micro-plasma + micro-wire feeding / powder feeding) This mode is suitable for thin plate welding, precision part repair or small size feature addition.

[0071] 1. System configuration and connection Welding torch: use the coaxial multifunctional welding torch described in the present application.

[0072] Power connection: the plasma arc power supply uses direct current positive connection (DCEN), uses micro-plasma mode, and the current range is 5-50A. The consumable electrode power supply can be turned off or use very low current (10-50A).

[0073] Wire feeding system: choose fine diameter welding wire (such as φ0.6mm or φ0.8mm), or turn off.

[0074] Powder feeding system: as the main or auxiliary material adding method. The powder feeding amount is accurately controlled at 5-30 g / min.

[0075] Gas supply system: all gas flow is reduced accordingly. Plasma gas 2-5 L / min, powder carrying gas 1-3 L / min, and shielding gas 8-15 L / min.

[0076] Cooling system: turn on the circulating water cooler, ensure that the water pressure is ≥0.4MPa and the flow is ≥4L / min, and fully cool all water cooling channels.

[0077] Motion execution mechanism: use high-precision robots or precision three-axis platforms.

[0078] 2. Welding process In this mode, the energy input mainly comes from the highly compressed micro-plasma arc, the arc is extremely stable and has strong directivity. If material needs to be added, the powder feeding, wire feeding, and wire-powder composite methods can be selected. Due to low heat input and small heat affected zone, it is very suitable for processing of heat-sensitive workpieces.

[0079] Through the description of the above specific embodiments, it can be seen that the coaxial wire and powder feeding multifunctional welding torch and system described in the present application can realize various functions such as large penetration welding, efficient cladding, additive manufacturing, precision repair, etc. on one set of equipment by flexibly configuring the power polarity, material delivery method and process parameters, greatly improving the utilization rate and process flexibility of the equipment, and providing a powerful solution for modern welding and additive manufacturing.

[0080] The above is only an individual embodiment of the present application, and it should be pointed out that, for those skilled in the art, several improvements and refinements can be made without departing from the principles of the present application, and any welding and additive manufacturing method using the structure of the present welding gun should be considered as the protection scope of the present application.

Claims

1. A multi-functional torch for a consumable electrode plasma arc welding, characterized in that, The welding torch comprises, from inside to outside, a center electrode nozzle (1), a shield gas channel (6), an inner plasma electrode nozzle (3), a plasma gas channel (7), an outer plasma electrode nozzle (5), an outer shield gas channel (8), and a shield nozzle (12). The center electrode nozzle (1) is used for coaxial transmission of a consumable electrode and is connected to a power source. The shield gas channel (6) surrounds the center electrode nozzle (1) and is used for transmission of a shield gas. The inner plasma electrode nozzle (3) surrounds the shield gas channel (6) and is internally provided with a hollow tungsten electrode (4) and an inner plasma electrode nozzle water cooling channel (9). The plasma gas channel (7) surrounds the inner plasma electrode nozzle (3) and is used for transmission of a plasma gas. The outer plasma electrode nozzle (5) surrounds the plasma gas channel (7) and is internally provided with an outer plasma electrode nozzle water cooling channel (10) and a powder feeding channel (11). The outer shield gas channel (8) surrounds the outer plasma electrode nozzle (5). The shield nozzle (12) is located at the outermost layer of the welding torch and is internally provided with a shield nozzle water cooling channel (13).

2. The multi-functional welding torch of claim 1, wherein, The center electrode nozzle (1) is connected to a consumable electrode power source, the hollow tungsten electrode (4) is connected to a plasma arc power source, and the polarity of the plasma arc power source and the consumable electrode power source is independently adjustable and can be configured as direct current positive or direct current reverse.

3. The multi-functional welding torch of claim 1, wherein, The powder feeding channel (11) is used for coaxial transmission of metal or alloy powder to an arc area and a molten pool by a carrier gas, and the powder feeding channel (11) is integrated in a multi-layer structure of the outer plasma electrode nozzle (5).

4. The multi-functional welding torch of claim 1, wherein, The inner plasma electrode nozzle water cooling channel (9), the outer plasma electrode nozzle water cooling channel (10), and the shield nozzle water cooling channel (13) are all connected to an external cooling system and are used for forced water cooling to maintain thermal stability of the welding torch under a large current.

5. A fused-plug plasma multi-functional welding system characterized by, The multifunctional welding torch comprises: The multifunctional welding torch according to any one of claims 1 to 4; A plasma arc power source connected to the hollow tungsten electrode (4) and used for generation of a sustaining arc and a main arc; A consumable electrode power source connected to the center electrode nozzle (1) and used for power supply for a welding wire; A wire feeding system used for control of a welding wire transmission speed and stability; A powder feeding system used for control of a transmission rate of metal or alloy powder; A gas supply system used for independent control of flow rates and pressures of a plasma gas, a shield gas, and a powder carrying gas; A cooling system used for circulation cooling for water cooling channels of the welding torch; A motion execution mechanism used for control of a motion trajectory of the welding torch relative to a workpiece; A central control system used for coordinated control of the plasma arc power source, the consumable electrode power source, the wire feeding system, the powder feeding system, the gas supply system, the cooling system, and the motion execution mechanism to realize automatic welding or additive manufacturing.

6. The welding system of claim 5, wherein, The plasma arc power source is configured as direct current positive, the consumable electrode power source is configured as direct current reverse, and the two power sources are independently adjustable or are controlled in parallel.

7. The welding system of claim 5, wherein, The wire feeding system adopts a servo motor to drive a wire feeding mechanism, and the powder feeding system comprises a powder tank and one of a Venturi powder feeder and a screw powder feeder.

8. The welding system of claim 5, wherein, The motion execution mechanism is a six-axis welding robot, a numerical control machine tool or a three-axis worktable.

9. A welding method based on the welding system of claim 5, characterized in that, The method comprises the following steps: Starting the gas supply system to start the delivery of shielding gas and plasma gas; Igniting the plasma arc to first form a non-transferred arc and then transfer to the workpiece to form a stable transferred plasma arc; Starting the wire feeding system and the consumable electrode power supply to make the welding wire enter the plasma arc area, ignite the MIG arc, and form a combined arc of the plasma arc and the MIG arc; Moving the welding torch by the motion execution mechanism to perform welding or additive manufacturing; When the arc is extinguished, the wire feeding and the consumable electrode power supply are stopped first, then the plasma arc current is attenuated, and the shielding gas is closed with a delay until the molten pool cools.

10. The welding method of claim 9, wherein, The process of welding or additive manufacturing comprises starting the powder feeding system to coaxially feed metal or alloy powder into the arc area through the carrier gas to form a weld or cladding layer together with the welding wire.

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