Multi-wire current sharing circuit and multi-wire concentric wire feeding device for plasma alternating arc additive material

Abstract

The invention discloses a multi-wire current sharing circuit and a multi-wire concentric wire feeding device for plasma alternating arc additive manufacturing, the multi-wire concentric wire feeding device comprises four groups of wire feeding pipes, a four-wire synchronous adjusting mechanism and a welding head protection gas hood, the four-wire synchronous adjusting mechanism is mounted outside a welding gun main body, and the welding head protection gas hood is mounted on the welding gun main body. The welding head protective gas hood is mounted at the tail end of the welding gun main body; the four sets of wire feeding pipes are evenly distributed around the outer portion of the welding gun body in the circumferential direction, the middle of each wire feeding pipe is movably connected with the four-wire synchronous adjusting mechanism, and the lower portion of each wire feeding pipe is hinged to the outer portion of the welding head protection gas hood. And a multi-wire current sharing circuit is connected between the four groups of wire feeding pipes and a tungsten electrode of the welding gun main body. According to the multi-wire current sharing circuit, the wire feeding mechanisms form a parallel circuit, and equivalent resistors are added to the wire feeding circuits, so that balanced distribution of current in each wire feeding channel is ensured, and the combustion and melting speeds of wires are ensured to be consistent; the synchronous and consistent wire feeding function in four directions can be achieved, and the operation efficiency and the welding precision and quality are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of welding methods and arc welding wire additive manufacturing, and particularly relates to a multi-wire current equalization circuit and a multi-wire concentric wire feeding device for high-speed and high-precision plasma alternating arc additive manufacturing. BACKGROUND

[0002] Arc additive manufacturing technology uses an electric arc or a plasma arc as a heat source to melt metal wire. Under the control of programs or software, it uses the principle of layer-by-layer cladding to manufacture three-dimensional metal blanks close to the product shape and size requirements from line-surface-body according to a three-dimensional digital model. This technology has the advantages of high material utilization rate, fast deposition rate, and relatively low equipment cost, and has been widely used in many fields such as aerospace, shipbuilding, and automobile industry. With the increasing demand for metal composite materials and functional gradient materials in modern industry, traditional single-wire arc additive manufacturing technology has been unable to meet these demands. Multi-wire composite arc additive manufacturing technology has gradually become the mainstream direction of research because it can provide better material composite capability and functional gradient control. This technology can melt multiple metal wires simultaneously during the manufacturing process, thereby achieving material compounding and gradient variation.

[0003] In multi-wire arc additive manufacturing technology, the wire feeding angle, the angle between multiple wires, the distance between the wire and the cladding layer, and the protective gas are all important process parameters that affect the cladding quality. In order to meet these needs, new wire feeding fixtures have been designed to achieve more precise wire feeding control. However, existing multi-wire feeding fixtures mostly only achieve structural centering design (such as fixed-position symmetrical arrangement) or partial integrated adjustment functions, such as single-direction synchronous movement, but do not deeply consider the problem of uneven energy input distribution between wires. Due to the slight difference in wire resistance in parallel circuits or the non-uniformity of arc energy distribution, the heat input of each wire deviates greatly, which in turn causes inconsistent melting rates. This "asynchronous melting rate" directly undermines the effectiveness of "structural centering", making it impossible for the wires to accurately reach the same arc center area, ultimately leading to forming deviations and poor consistency in the cladding layer. Traditional bypass wire feeding additive technology often results in poor operability due to the need for parallel consistency between the wire feeding direction and the welding direction, limiting the flexibility and application range of welding and additive operations.

[0004] In order to improve the cladding efficiency, scholars have explored TIG welding technology with bypass wire feeding, which has significantly improved the wire melting speed by improving the wire feeding method, thereby further promoting the development of arc additive manufacturing technology. However, with the improvement of cladding efficiency, the heat input problem gradually emerges. The introduction of multi-wire additive technology has solved the problem of cladding efficiency to some extent, but due to the large heat input, it affects the forming quality and performance of the material. SUMMARY

[0005] The purpose of the present application is to solve the problems and challenges existing in the prior art, and to provide a multi-wire current equalization circuit and a multi-wire concentric wire feeding device for plasma alternating arc additive manufacturing, so as to further improve the flexibility and operability of the arc additive manufacturing technology, and to improve the forming quality and precision of welding and additive manufacturing.

[0006] In order to achieve the above-mentioned purpose, the present application is realized by the following technical scheme:

[0007] A multi-wire current equalization circuit for plasma alternating arc additive manufacturing comprises a variable polarity power supply, one electrode of the variable polarity power supply is connected to a welding gun body, the other electrode is divided into two paths and is connected in parallel to welding wires of a wire feeding pipe and a workpiece substrate, and the number of wire feeding pipes is at least two; a first diode D1 and a resistor R1 with a resistance value R are connected in series on the connection line of each welding wire; a second diode D2 is connected in series on the connection line of the workpiece substrate; the directions of the first diode and the second diode are opposite; and the resistance value R is much larger than the resistance value of the welding wire.

[0008] Further, the resistance value of the resistor R1 is at least 20 times the resistance value of the welding wire in the current equalization circuit.

[0009] Further, the first diode and the second diode are both IGBT diodes.

[0010] The present application also provides a multi-wire concentric wire feeding device for high-speed and high-precision plasma alternating arc additive manufacturing, four groups of wire feeding pipes, a four-wire synchronous adjusting mechanism and a welding head protective gas cover, the four-wire synchronous adjusting mechanism is installed outside the welding gun body, and the welding head protective gas cover is installed at the end of the welding gun body; the four groups of wire feeding pipes are evenly arranged in the circumferential direction around the outside of the welding gun body, the middle part of each wire feeding pipe is movably connected with the four-wire synchronous adjusting mechanism, and the lower part is hingedly connected with the outside of the welding head protective gas cover; and the multi-wire current equalization circuit described above is connected between the four groups of wire feeding pipes and the tungsten electrode of the welding gun body.

[0011] Further, the multi-wire current equalization circuit comprises a variable polarity power supply, one electrode of the variable polarity power supply is connected to the welding gun body, the other electrode is divided into two paths and is connected in parallel to the welding wires of the four groups of wire feeding pipes and the workpiece substrate; a first diode D1 and a resistor R1 with a resistance value R are connected in series on the connection line of each welding wire; a second diode D2 is connected in series on the connection line of the workpiece substrate; the directions of the first diode and the second diode are opposite; and the resistance value R is much larger than the resistance value of the welding wire.

[0012] Further, a cooling module is arranged on the welding gun body, and the resistor R1 is arranged in the cooling module.

[0013] Further, the four-wire synchronous adjusting mechanism comprises a fixed rack, a screw pair driving assembly, a rigid linkage platform, four sets of connecting rod transmission assemblies and four sets of wire feeding pipe mounting supports, the fixed rack is installed on the welding gun body, the screw pair driving assembly is fixedly installed on the fixed rack, the rigid linkage platform is connected with the movable end of the screw pair driving assembly, the four sets of connecting rod transmission assemblies are installed on the bottom surface of the rigid linkage platform and are evenly distributed around the welding gun body in a circumferential direction, one set of wire feeding pipe mounting support is installed on each connecting rod transmission assembly, and the wire feeding pipe mounting supports are hingedly connected with the middle portions of the wire feeding pipes.

[0014] Further, the lower portion of the wire feeding pipe is a wire outlet end, the upper portion is a wire inlet end, a wire feeding collimation mechanism is installed outside the wire inlet end of the wire feeding pipe, and the wire feeding collimation mechanism comprises a plurality of collimation rollers arranged in opposition and staggered.

[0015] Further, a molten drop auxiliary transition mechanism is installed at the lower portion of the wire feeding pipe, and the molten drop auxiliary transition mechanism comprises a wire feeding brake assembly and a control assembly.

[0016] Further, the welding head protective gas cover outer wall is provided with gas inlet holes.

[0017] The multi-wire equal current circuit in the application makes the wire feeding mechanisms constitute a parallel circuit, and equal resistance is added to the multi-wire feeding circuit, so as to ensure the balanced distribution of current in each wire feeding channel, thereby ensuring the consistent burning and melting speed of the wire material and improving the forming quality and precision of welding and additive operation.

[0018] The multi-wire concentric wire feeding device of the application realizes the synchronous and consistent wire feeding function in four directions by designing four synchronous pairs of wire feeding mechanisms, significantly improves the operation efficiency and quality, and the design of the four synchronous pairs of wire feeding channels enables more materials to be processed at the same time, further shortens the operation cycle and improves the cladding efficiency and additive speed. The special four-channel wire feeding mechanism adopts stable screw pair transmission, so that the four wire feeding pipes can move synchronously and consistently when adjusting the wire feeding angle, reduces the error of manually adjusting the angles of the four wire feeding pipes, and forms integrated adjustment. The synchronous movement and consistent burning of the wire material in each direction are realized by combining the multi-wire equal current circuit, and the multi-dimensional collaborative design realizes the goal of high-speed and high-precision plasma alternating arc additive manufacturing. The resistance of the multi-wire equal current circuit in the wire feeding device is further added to the heat dissipation of the welding gun, which can prevent the resistance value change and heating out of control caused by temperature rise of the resistance.

[0019] The device of the present application also inherits the advantages of the variable polarity technology, and the time-sharing conduction arc is established through the multi-electrode system, the heat input of the base material is reduced, that is, the time-sharing conduction arc of the multi-wire is established by using the characteristics of instantaneous conversion of the electrode, the current over the base material is effectively reduced, the heat input is significantly reduced, the problem of heat excess of the base material is solved, and the forming quality of the material is improved. BRIEF DESCRIPTION OF DRAWINGS

[0020] Fig. 1 A schematic diagram of a multi-wire current sharing circuit of the present application is shown in the figure.

[0021] Fig. 2 A schematic diagram of the structure of a multi-wire concentric wire feeding device of the present application is shown in the figure.

[0022] Fig. 3 A schematic diagram of the structure of a droplet auxiliary transition mechanism in the present application is shown in the figure.

[0023] In the figure, 1 is a welding gun body; 11 is a cooling module; 2 is a wire feeding pipe; 21 is a wire outlet end; 22 is a wire inlet end; 23 is a wire feeding collimation mechanism; 231 is a collimation roller; 24 is a droplet auxiliary transition mechanism; 3 is a four-wire synchronous adjustment mechanism; 31 is a fixed frame; 32 is a screw rod pair driving assembly; 33 is a rigid linkage platform; 34 is a connecting rod transmission assembly; 35 is a wire feeding pipe mounting bracket; 4 is a welding head protective gas cover; 41 is an air inlet hole; 5 is a variable polarity power supply; 6 is a workpiece base plate. DETAILED DESCRIPTION

[0024] The present application will be further described in detail below in combination with the drawings and examples.

[0025] In the description of the embodiments of the present application, it should be noted that the orientations or positional relationships indicated by the terms “center”, “longitudinal”, “transverse”, “upper”, “lower”, “front”, “rear”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inner”, “outer” and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the embodiments of the present application. In addition, the terms “first”, “second”, “third” are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0026] In the description of the embodiments of the present application, it should be noted that unless specifically defined and limited otherwise, the terms "connected", "connected to", "connection" should be interpreted broadly, for example, can be fixed connection, can also be detachable connection, or integral connection; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0027] In the embodiments of the present application, unless specifically defined and limited otherwise, the first feature is "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature can be "above", "over" and "on" the second feature, which can be that the first feature is directly above or obliquely above the second feature, or only means that the horizontal height of the first feature is higher than that of the second feature. The first feature can be "below", "under" and "under" the second feature, which can be that the first feature is directly below or obliquely below the second feature, or only means that the horizontal height of the first feature is less than that of the second feature.

[0028] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine the different embodiments or examples described in the present application and the features of the different embodiments or examples without contradiction.

[0029] As shown in Figs. 1 to 3 A multi-wire current equalization circuit of the present application for plasma alternating arc additive manufacturing includes a variable polarity power supply 5, a welding gun is a plasma arc welding gun, one electrode of the variable polarity power supply 5 is connected to the tungsten electrode of the welding gun body 1, the other electrode is divided into two paths and connected in parallel to the welding wire of the wire feeding pipe 2 and the workpiece substrate 6, and the number of wire feeding pipes is at least 2; A first diode D1 and a resistor R1 with a resistance value R are connected in series on the connection line of each welding wire, a second diode D2 is connected in series on the connection line of the workpiece substrate, the directions of the first diode D1 and the second diode D2 are opposite, and the resistance value R is much larger than the resistance value of the welding wire.

[0030] In a specific embodiment, the resistance value R of the resistor R1 is at least 20 times, further 20-50 times the resistance value of the welding wire in the current sharing circuit, in a specific embodiment, the resistance value of the welding wire in the multi-wire current sharing circuit is about 0.05Ω, and the resistance value R of the resistor R1 can be 1Ω-2.5Ω, preferably 1Ω. The resistors R1 corresponding to the wire feeding pipes are in plurality, and all have the same small resistance value. Since the voltages of the parallel circuits are equal, the current I of the parallel circuit is more affected by the resistor R1, and the setting of the resistor R1 makes the heat input of each welding wire from I 2 Rmain, so that each equal distribution can be realized, and the problem of uneven current caused by the resistance difference of the welding wire of each wire feeding pipe is completely solved, the balanced distribution of the current in each wire feeding channel is ensured, and the consistency of the wire melting rate of the multi-wire is ensured.

[0031] In some embodiments, the first diode D1 and the second diode D2 are both IGBT diodes. In the polarity changing period of the welding power supply, due to the blocking effect of the first diode D1 and the second diode D2, the welding torch can only arc with one of the welding wire or the workpiece substrate at the same time; in DCEN direct current reverse connection, due to the effect of the diode, the current cannot pass through the workpiece substrate, at this time the current is forced to conduct between the welding torch and the welding wire, at this time the welding torch is negative and the welding wire is positive; in DCEP direct current positive connection, due to the effect of the diode, the current cannot pass through the welding wire, at this time the current is forced to conduct between the welding torch and the workpiece substrate, at this time the welding torch is positive and the workpiece substrate is negative; thus in a polarity changing period, two arcs are alternately ignited to form an alternating polarity arc.

[0032] The application also provides a multi-wire concentric wire feeding device for high-speed and high-precision plasma alternating arc additive manufacturing, comprising four groups of wire feeding pipes 2, a four-wire synchronous adjusting mechanism 3 and a welding head protective gas cover 4, the four groups of wire feeding pipes 2 are connected between the tungsten electrode of the welding torch body 1 and the four-wire current sharing circuit as described above; the four-wire synchronous adjusting mechanism 3 is installed outside the welding torch body 1, and the welding head protective gas cover 4 is installed at the end of the welding torch body 1, the four groups of wire feeding pipes 2 are evenly arranged in the circumference of the welding torch body 1, the middle part of each wire feeding pipe 2 is movably connected with the four-wire synchronous adjusting mechanism 3, and the lower part is hingedly connected with the outside of the welding head protective gas cover 4, the four groups of wire feeding pipes 2 are arranged around the plasma arc center axis of the welding torch body 1, and the structure allows concentric synchronous accommodation and adjustment.

[0033] In specific embodiments, the multi-wire current equalization circuit includes a variable polarity power supply 5, one electrode of which is connected to the welding gun body 1, and the other electrode is divided into two paths and connected in parallel to the welding wires of the four groups of wire feeding pipes and the workpiece substrate; a first diode D1 and a resistor R1 with a resistance value R are connected in series on the connection line of each welding wire, and a second diode D2 is connected in series on the connection line of the workpiece substrate, the directions of the first diode D1 and the second diode D2 are opposite, and the resistance value R of the resistor R1 is much larger than the resistance of the welding wire.

[0034] The four wire feeding pipes 2 in the application and the tungsten electrode and the workpiece substrate 6 constitute a six-electrode system of plasma arc welding, wherein the four wire feeding pipes 2 are arranged uniformly around the circumference of the tungsten electrode, and the ends thereof are located in the high-energy density area of the Gaussian-like arc. Compared with the conventional single-wire or double-wire wire feeding design, the wire material can only cover the local area of the arc energy distribution, and the ends of the four wire feeding pipes form a multi-directional “X” type coverage to the high-energy area of the Gaussian-like arc, so that the heat radiation and plasma energy generated by the arc are synchronously absorbed by the multiple wires, thereby improving the energy utilization rate. The above design reduces the energy loss in the welding or additive process, improves the wire melting speed and cladding efficiency, and achieves the energy optimization goal of high-speed and high-precision additive manufacturing.

[0035] The workpiece substrate 6 is horizontally placed below the wire feeding pipes and the tungsten electrode; by adjusting the energy output mode of the plasma arc, the plasma arc periodically alternately acts between the two working stages of wire melting and workpiece substrate 6 heating. In the wire melting stage, the plasma arc energy is focused on the ends of the four wire electrodes, so that the wire material is melted to form droplets and deposited on the surface of the workpiece substrate 6; in the workpiece substrate 6 heating stage, the plasma arc energy is diffused to the deposition area of the workpiece substrate 6. The switching between the above two stages is precisely controlled by the variable polarity duty cycle parameter, so as to realize the proportional distribution of the plasma arc heat input between the wire melting and the workpiece substrate heating, so as to ensure the balance between the stability of the molten pool and the heat input of the workpiece substrate 6 in the additive process. The spatial energy distribution of the plasma arc presents a Gaussian-like curve, and the high-energy density area is concentrated near the central axis, and gradually decays towards the periphery. The four wire feeding pipes are uniformly arranged around the central axis of the tungsten electrode plasma arc, and the ends thereof are located in the high-energy density area of the Gaussian-like arc. Compared with the conventional single-wire or double-wire wire feeding design, the wire material can only cover the local area of the arc energy distribution, and the ends of the four wire feeding pipes form a multi-directional “X” type coverage to the high-energy area of the Gaussian-like arc, so that the heat radiation and plasma energy generated by the arc are synchronously absorbed by the multiple wires, thereby improving the energy utilization rate. The above design reduces the energy loss in the welding or additive process, improves the wire melting speed and cladding efficiency, and achieves the energy optimization goal of high-speed and high-precision additive manufacturing.

[0036] In some embodiments, the cooling module 11 is arranged on the welding torch body 1, and the resistor R1 is arranged in the cooling module 11. The resistor R1 is integrated in the cooling module 11 of the welding torch body 1, and is cooled in real time by a forced air cooling or water cooling system of the cooling module 11 to prevent the resistor R1 from drifting due to temperature rise and to ensure long-term stability of current distribution of each wire circuit.

[0037] The four-wire synchronous adjustment mechanism 3 has three degrees of freedom for synchronously adjusting the height, angle and center distance of the plasma arc of the four wire feeding pipes 2 to realize accurate control of the wire feeding position and arc heat input. In some embodiments, the four-wire synchronous adjustment mechanism 3 includes a fixed frame 31, a screw pair driving assembly 32, a rigid linkage platform 33, four sets of linkage transmission assemblies 34 and four sets of wire feeding pipe mounting brackets 35. The fixed frame is mounted on the welding torch body 1, the screw pair driving assembly 32 is fixedly mounted on the fixed frame 31, the rigid linkage platform 33 is connected with a movable end of the screw pair driving assembly 32, the four sets of linkage transmission assemblies 34 are mounted on the bottom surface of the rigid linkage platform 33 and are uniformly distributed in the circumferential direction around the welding torch body 1, and each linkage transmission assembly 34 is correspondingly provided with a set of wire feeding pipe mounting brackets 35, and the wire feeding pipe mounting bracket 35 is hingedly connected with the middle part of the wire feeding pipe 2.

[0038] The four-wire synchronous adjustment mechanism 3 can realize high-precision radial synchronous adjustment of the four wire feeding pipes 2, and stable transmission of the screw pair driving assembly 32 makes the adjustment of the wire feeding angle more convenient and stable. The wire material with consistent melting rate can be synchronously fed to the center region of the arc, and the “heat input balance” and “position synchronization” of the wire material form a synergistic effect, which significantly improves the forming precision and interlayer bonding quality of the additive manufacturing.

[0039] The driving member of the screw pair driving assembly 32 can be a motor or a manual crank (the motor is connected with the screw through a shaft coupling, and the manual crank is directly connected with the screw). When the driving member drives the screw to rotate, the rigid linkage platform 33 is accurately lifted in the vertical direction. The rigid linkage platform 33 has a rectangular frame structure, and bolt connection holes are formed in four corners thereof. Each set of linkage transmission assemblies 34 includes two detachably connected first and second linkages. One end of the first linkage is fixedly locked in the bolt connection hole in the corner of the rigid linkage platform 33, and the tail end of the first linkage is detachably connected with the head end of the second linkage through a pin or a bolt to form a length-adjustable structure. The tail end of the second linkage is the wire feeding pipe mounting bracket 35. The wire feeding pipe 2 is hingedly connected with the tail end of the second linkage. When the rigid linkage platform 33 is lifted, the four sets of symmetrically arranged linkage transmission mechanisms 34 synchronously convert the vertical motion into radial motion of the wire feeding pipe mounting bracket 35. When the rigid linkage platform 33 is lifted, the wire feeding pipe mounting bracket 35 is pulled away from the center axis of the plasma arc. When the rigid linkage platform 33 is lowered, the wire feeding pipe mounting bracket 35 is pushed to approach the center axis. The connection positions and motion trajectories of the four wire feeding pipes 2 are completely consistent.

[0040] In specific embodiments, the wire feeding tube mounting bracket 35 includes a clamping body and a locking bolt, a plurality of shallow clamping grooves are formed on the wire feeding tube 2 in an axial direction, the clamping device is clamped in the shallow clamping groove through the locking bolt, and detachable fixing and axial multi-stage adjustment are achieved. Through the symmetrical design of the four sets of connecting rod transmission mechanisms, the high-precision transmission of the screw pair, and the rigid linkage platform, the synchronous movement of the four wire feeding tube mounting brackets 35 is ensured, and high-precision synchronous adjustment of the four wire feeding tubes is achieved.

[0041] In some embodiments, the lower part of the wire feeding tube 2 is the wire outlet end 21, and the upper part is the wire inlet end 22. A wire feeding collimation mechanism 23 is mounted on the outside of the wire inlet end 22 of the wire feeding tube 2. The wire feeding collimation mechanism 23 includes a plurality of collimation rollers 231 arranged in opposition and staggered in multiple groups. The wire feeding collimation mechanism 23 uses multiple sets of opposing collimation rollers to straighten the wire, remove the internal bending stress of the wire itself, and ensure that the wire is straightly fed into the center area of the welding pool in a taut state.

[0042] In some embodiments, a droplet auxiliary transition mechanism 24 is mounted on the lower part of the wire feeding tube 2 to apply an external force to the welding wire and the droplet, and promote the uniform transition and stable deposition of the four wire droplets. The droplet auxiliary transition mechanism 24 includes a wire feeding brake assembly and a control assembly. The wire feeding brake assembly can use two wire clamping brakes controlled by the control assembly to clamp the wire in the wire feeding tube 2.

[0043] During the processing, the welding wire in the wire feeding tube 2 is continuously fed to the workpiece substrate 6, the end of the welding wire is melted to form a droplet under the action of the heat source, the droplet contacts the molten pool and transitions into the molten pool under the action of surface tension, and the component is formed; when the wire feeding is stopped, the welding wire is clamped by reducing the distance between the two brake wheels, so that the welding wire stops moving, the previous droplet is separated from the welding wire and contacts the molten pool, and a liquid bridge is formed between the welding wire and the molten pool, ensuring the stability of the metal droplet transition process.

[0044] In preferred embodiments, the welding head protective gas cover 4 has gas inlet holes 41 formed on the outer wall. The welding head protective gas cover 4 adopts a cavity structure with an enlarged volume, the opening size of the cavity is matched with the multi-wire and plasma arc operation range, a plurality of circumferentially uniformly distributed annular gas inlet holes 41 are arranged on the top of the cavity, so that the protective gas can fully and uniformly fill the gap between the welding torch and the welding part; through the above structure design, the protective atmosphere covers the entire welding operation area, i.e. covering the wire feeding path of the four wires and the plasma arc action area, significantly expanding the protection range and ensuring the welding quality of additive manufacturing.

[0045] The device of the present application realizes the proportional distribution of the heat required for the deposition of the wire and the heat required for the heating of the workpiece substrate by periodically switching the target area of the thermal action of the plasma arc; combined with the heat input balancing control, droplet transfer assistance and adjustable wire feeding position structure, it realizes high-speed and high-precision arc additive manufacturing, and through multi-dimensional collaborative design, it realizes the goal of high-speed and high-precision plasma alternating arc additive manufacturing.

[0046] By ensuring the consistency of the current in the four wire feeding channels, the preset current balance state is achieved, the melting and burning speed of the wire is consistent, and the forming quality and precision of the welding and additive operation are improved. The design of tungsten electrode single heat source four-channel synchronous wire feeding makes the heat radiation generated by the arc more effectively recycled, reduces the energy loss in the welding and additive process, and improves the energy utilization rate. By periodically switching the main target area of the thermal action of the plasma arc, the proportional distribution of the heat required for the deposition of the wire and the heat required for the heating of the substrate is realized, which significantly reduces the heat input of the current to the base material, effectively solves the problem of excessive heat of the base material, and improves the forming quality of the material.

[0047] The device of the present application can accurately control the heat input in the welding process, optimize the shape and size of the welding pool, reduce welding defects, improve the overall quality of the welded joint, and realize a more efficient and stable welding process. Since the heat input is effectively controlled, unnecessary energy consumption and environmental pollution are also reduced, which is in line with the concept of green manufacturing.

[0048] The device design of the present application can be widely used in aerospace, shipbuilding, automobile industry and other fields, meeting the needs of different industries for high-quality and high-efficiency manufacturing technology. By adjusting the wire feeding speed, current parameters and other parameters, it can adapt to the welding and additive needs of different materials, enhancing the adaptability and flexibility of the technology.

[0049] The specific embodiments in the present application are only an explanation of the present application, not a limitation of the present application, and those skilled in the art can make modifications to the embodiments without creative contribution after reading the present specification, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A multi-wire current-sharing circuit for plasma alternating arc additive manufacturing, characterized in that, The system includes a polarity-changing power supply (5), one electrode of which is connected to the welding torch body, and the other electrode is divided into two paths and connected in parallel to the welding wire in the wire feeding tube and the workpiece substrate, respectively. The number of wire feeding tubes is at least 2. A first diode D1 and a resistor R1 with a resistance value of R are connected in series in the wiring with each welding wire. A second diode D2 is connected in series in the wiring with the workpiece substrate. The first diode and the second diode are in opposite directions, and the resistance value R is much greater than the resistance value of the welding wire.

2. The multi-wire current sharing circuit for plasma alternating arc additive manufacturing according to claim 1, characterized in that, The resistance value of resistor R1 is at least 20 times the resistance value of the welding wire in the current sharing circuit.

3. The multi-wire current sharing circuit for plasma alternating arc additive manufacturing according to claim 1, characterized in that, Both the first diode and the second diode are IGBT diodes.

4. A multi-wire concentric wire feeding device for plasma alternating arc additive manufacturing, characterized in that, It includes four sets of wire feeding tubes (2), a four-wire synchronous adjustment mechanism (3) and a welding head protective gas cover (4). The four-wire synchronous adjustment mechanism is installed outside the welding torch body (1), and the welding head protective gas cover is installed at the end of the welding torch body. Four sets of wire feed tubes are evenly arranged around the outer circumference of the welding torch body. The middle part of each wire feed tube is movably connected to the four-wire synchronous adjustment mechanism, and the lower part is hinged to the outside of the welding head protective gas cover. The four sets of wire feed tubes are connected to the tungsten electrode of the welding torch body by a multi-wire current sharing circuit as described in claim 1 or 2.

5. The multi-wire concentric wire feeding device for plasma alternating arc additive manufacturing according to claim 4, characterized in that, The multi-wire current sharing circuit includes a variable polarity power supply (5). One electrode of the variable polarity power supply is connected to the welding torch body, and the other electrode is divided into two paths and connected in parallel to the welding wires of the four sets of wire feeding tubes and the workpiece substrate. A first diode D1 and a resistor R1 with a resistance value of R are connected in series in the wiring with each welding wire. A second diode D2 is connected in series in the wiring with the workpiece substrate. The first diode and the second diode are in opposite directions, and the resistance value R is much smaller than the resistance value of the welding wire.

6. The multi-wire concentric wire feeding device for plasma alternating arc additive manufacturing according to claim 5, characterized in that, A cooling module is provided on the welding torch body, and the resistor R1 is located inside the cooling module.

7. The multi-wire concentric wire feeding device for plasma alternating arc additive manufacturing according to claim 4, characterized in that, The four-wire synchronous adjustment mechanism includes a fixed frame (31), a lead screw drive assembly (32), a rigid linkage platform (33), four sets of linkage transmission assemblies (34), and four sets of wire feeding tube mounting brackets (35). The fixed frame is installed on the welding torch body, the lead screw drive assembly is fixedly installed on the fixed frame, the rigid linkage platform is connected to the movable end of the lead screw drive assembly, the four sets of linkage transmission assemblies are installed on the bottom surface of the rigid linkage platform and are evenly distributed around the welding torch body, and a set of wire feeding tube mounting brackets is installed on each linkage transmission assembly. The wire feeding tube mounting brackets are hinged to the middle of the wire feeding tube.

8. The multi-wire concentric wire feeding device for plasma alternating arc additive manufacturing according to claim 4, characterized in that, The lower part of the wire feeding tube is the wire exit end (21), and the upper part is the wire inlet end (22). A wire feeding alignment mechanism (23) is installed on the outside of the wire inlet end of the wire feeding tube. The wire feeding alignment mechanism includes multiple sets of alignment rollers (231) arranged in opposite directions.

9. The multi-wire concentric wire feeding device for plasma alternating arc additive manufacturing according to claim 4, characterized in that, The lower part of the wire feeding tube is equipped with a droplet auxiliary transition mechanism (24), which includes a wire feeding braking assembly and a control assembly.

10. The multi-wire concentric wire feeding device for plasma alternating arc additive manufacturing according to claim 4, characterized in that, An air inlet (41) is provided on the outer wall of the protective gas cover of the welding head.

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