A double-wire additive gun body based on cold cathode electron beam in-fiber light additive

Abstract

The application discloses a double-wire additive gun body based on cold cathode electron beam internal wire melting additive manufacturing, which comprises an anode, an insulator, an internal cathode, an external cathode, a ring-shaped wire nozzle, a discharge cavity, an upper joint plate, a wire guide pipe, a pipe for cooling the cathode and a high-voltage power supply; the anode is internally provided with the insulator, the lower middle part of the insulator is provided with the internal cathode, the external cathode is annular and connected with the lower part of the insulator; the insulator is internally provided with through holes for the two wire guide pipes, a water cooling channel, a gas feeding channel and a high-voltage power supply channel, the ring-shaped wire nozzle arranged at the lower end of the insulator is a conical tubular with a wide upper part and a narrow lower part, the pipe wall surface of the ring-shaped wire nozzle is provided with a wire feeding channel communicated with the wire guide pipe, the wire feeding double channels in the ring-shaped wire nozzle make the wire passing through point to the annular electron beam focal point, and the discharge cavity is formed between the internal cathode, the external cathode, the ring-shaped wire nozzle and the lower part of the anode shell. The application realizes multiple special functions of parts and adopts double wires to carry out internal wire melting additive manufacturing.

Description

Technical Field

[0001] This invention belongs to the field of material forming, specifically relating to a dual-wire additive manufacturing gun body based on cold cathode electron beam photoluminescence fused wire additive manufacturing. Background Technology

[0002] Electron beam fused wire additive manufacturing is a novel technology characterized by high efficiency, low cost, and rapid response, particularly suitable for the rapid fabrication of large metal components. Several research institutions both domestically and internationally have conducted in-depth research on this technology. Currently, the electron guns commonly used in electron beam fused wire additive manufacturing are hot cathode type, which generally has a short cathode lifespan, directly impacting the quality and processing efficiency of electron beam fused wire additive manufacturing. Due to the inherent characteristic of hot cathode electron guns that the electron beam must exit along its axis, the filament used in fused wire additive manufacturing must be fed at an angle near the electron gun exit point, i.e., external filament feeding. This method cannot guarantee a constant angle between the filament feeding direction and the gun's additive direction when additively manufacturing complex components, thus affecting the additive forming quality and the flexibility of the additive path. These reasons have prevented the large-scale application of electron beam fused wire additive manufacturing technology. Cold cathode gas discharge electron guns, on the other hand, have the advantages of long cathode lifespan, high power, and diverse beam morphology. By optimizing the structure of cold cathode electron guns, the effect of internal fused wire feeding can be achieved. Application CN201810235235.7 discloses an electron gun device for coaxial filament additive manufacturing. However, this device can only use one type of filament for additive manufacturing and cannot perform additive manufacturing with two different filaments simultaneously or interchangeably. Application CN202211218271.5 discloses a method and device for in-situ alloying of heterogeneous dual filaments with plasma arc additive manufacturing, but this device cannot achieve in-situ filament feeding and has a "shadow area". Using two filaments with excellent properties to integrally form parts can improve the performance of the parts and realize a variety of special functions. In-situ filament feeding can effectively solve the problem of the "shadow area" and thus meet the needs of products with higher requirements. Summary of the Invention

[0003] The purpose of this invention is to provide a dual-wire additive manufacturing gun body based on cold cathode electron beam in-fuse additive manufacturing, which improves the performance of components, realizes a variety of special functions of components, and uses dual wires for in-fuse additive manufacturing.

[0004] The technical solution to achieve the purpose of this invention is: a dual-wire additive manufacturing gun body based on cold cathode electron beam optical in-wire additive manufacturing, including an anode, an insulator, an inner cathode, an outer cathode, an annular nozzle, a discharge cavity, an upper plate, a wire guide tube, a pipe for cooling the cathode, and a high-voltage power supply.

[0005] The anode is a shell composed of a cylindrical section and a conical section. The upper part of the cylindrical section of the anode has a flange that connects to the upper plate. An insulator is installed inside the anode. An inner cathode is located in the middle of the lower end of the insulator. The outer cathode is annular and connected to the lower part of the insulator. The insulator has a through hole for two guide wire tubes to pass through, a water cooling channel, an air supply channel, and a high-voltage power supply channel. The annular nozzle located at the lower end of the insulator is a conical tube that is wider at the top and narrower at the bottom. The tube wall of the annular nozzle has a wire feeding channel that communicates with the guide wire tube. The connection position between the annular nozzle and the insulator is located between the inner cathode and the outer cathode. The dual wire feeding channels in the annular nozzle allow the passing wire to point towards the focal point of the annular electron beam. A discharge cavity is formed between the inner cathode, the outer cathode, the annular nozzle, and the lower part of the anode shell.

[0006] Furthermore, it also includes a wire feeding seal, the upper end of which is connected to the wire feeding mechanism and the lower end is connected to the wire guide tube. The wire guide tube passes through the upper plate and the insulator and communicates with the annular wire nozzle at the lower end of the insulator.

[0007] Furthermore, the upper plate and the anode are connected by bolts, and both the inner cathode and the outer cathode are detachably connected to the insulator.

[0008] Furthermore, both the inner cathode and the outer cathode are provided with grooves for cooling water to pass through;

[0009] The pipes for cooling the cathode include an outer cathode inlet pipe, an inner cathode inlet pipe, an inner cathode outlet pipe, and an outer cathode outlet pipe. Cooling water enters the sealed groove formed by the outer cathode and the insulator from the outer cathode inlet pipe. The cooling water in the groove enters the inner cathode inlet pipe through the outer cathode outlet pipe and the connecting pipe located on the upper plate, and then flows out through the inner cathode outlet pipe, thereby achieving cooling of the inner and outer cathodes.

[0010] Furthermore, the two guide tubes are symmetrically arranged about the electron gun axis. The two guide tubes are connected by a bend between the upper plate and the insulator, and a sealing ring is provided at the connection. The upper part of the guide tube is parallel to the electron gun axis, and the lower part points towards the beam focus.

[0011] Furthermore, a 20-30kV high-voltage power supply is applied between the inner cathode, outer cathode, and anode, and the ring-shaped screw is grounded.

[0012] Furthermore, the upper end face of the annular screw nozzle is provided with an air outlet groove, through which the gas inside and outside the annular screw nozzle is connected;

[0013] The insulator is coaxially mounted with the inner cathode, outer cathode, anode, and annular thread nozzle.

[0014] A dual-wire additive manufacturing gun system based on cold cathode electron beam in-filament additive manufacturing includes the aforementioned dual-wire additive manufacturing gun.

[0015] Furthermore, it also includes a wire feeding mechanism and a worktable located inside the vacuum chamber;

[0016] The metal wire is fed into the wire guide tube through the wire feeding mechanism, and the forming part of the dual-wire additive manufacturing gun body is located in the vacuum chamber and is formed in a vacuum environment.

[0017] A method for dual-filament additive manufacturing using the above-described system includes the following steps:

[0018] Step (1): Feed the wire to 20±2mm below the annular wire nozzle, clamp the wire, and the wire diameter should not exceed 2mm;

[0019] Step (2): Place the substrate on the worktable, clamp the four corners of the substrate, and push the worktable into the vacuum chamber so that the substrate is located below the electron gun.

[0020] Step (3): Close the vacuum chamber door and evacuate to 1×10⁻⁶. -1 the following;

[0021] Step (4): Preheat the electron gun;

[0022] Step (5): Adjust the worktable so that the wire is aligned with the starting position of the substrate, and record the X, Y, and Z coordinates of the starting position;

[0023] Step (6): Input the starting position to define the original coordinates of the additive manufacturing (0, 0), and input the additive manufacturing trajectory of the worktable;

[0024] Step (7): Turn on the gas flow meter, introduce gas into the vacuum chamber, and stabilize the vacuum level;

[0025] Step (8): Turn on the power, record the beam current value and high voltage value, adjust the gas flow rate, and scan the substrate for preheating after the beam current stabilizes. Start additive manufacturing, and use the knob to fine-tune the Z-axis position so that the molten droplet and the substrate can achieve a bridging transition. On the worktable in the vacuum chamber, the annular cold cathode electron beam melts the metal wire at the electrostatic convergence position, i.e. the focal position. The molten metal wire is stacked layer by layer according to the predetermined trajectory, and finally forms a shaped part.

[0026] Compared with the prior art, the significant advantages of this invention are:

[0027] The invention adds an inner cathode that can act as a compensating beam to melt refractory metals and can also play a role in remelting the molten pool; the electron beam can be successfully focused into a focal point to melt the wire without hitting the annular nozzle and anode and causing damage; the annular nozzle can simultaneously restrict the inner and outer cathodes and will not interfere with the electron beam, allowing it to focus normally.

[0028] This invention enables additive manufacturing using two or more types of filaments, improving the performance of components and enabling them to perform a variety of special functions. The optical in-fusible filament can effectively solve the problem of the "shadow area," thereby meeting the needs of products with higher requirements. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the internal cavity of the dual-wire additive manufacturing gun body based on cold cathode electron beam optical fused wire additive manufacturing according to the present invention; wherein (a) is the front view and (b) is the top view after removing the wire feed sealer.

[0030] Figure 2 This is a schematic diagram of the dual-wire additive manufacturing gun system based on cold cathode electron beam photoelectric in-wire additive manufacturing according to the present invention.

[0031] Figure 3 This is a schematic diagram of the installation of the internal and external cathodes of the dual-wire additive gun based on cold cathode electron beam optical fused wire additive manufacturing according to the present invention.

[0032] Figure 4 This is a schematic diagram of the annular nozzle of the dual-wire additive manufacturing gun body based on cold cathode electron beam optical fused wire additive manufacturing of the present invention.

[0033] Figure 5 This is a simulation diagram of the dual-wire additive manufacturing gun body of the present invention.

[0034] Explanation of reference numerals in the attached figures:

[0035] 1-Metal wire, 2-Wire feeding sealer, 3-Anode, 4-Insulator, 5-Inner cathode, 6-Outer cathode, 7-Annular wire nozzle, 8-Discharge chamber, 9-Upper plate, 10-Air inlet pipe, 11-Outer cathode water inlet pipe, 12-Inner cathode water inlet pipe, 13-Inner cathode water outlet pipe, 14-Wire guide pipe, 15-Outer cathode water outlet pipe, 16-High voltage power supply, 17-High voltage power supply line, 18-Air outlet groove, 19-Wire feeding mechanism, 20-Air supply device, 21-Vacuum chamber, 22-Workbench, 23-Formed part. Detailed Implementation

[0036] The present invention will now be described in further detail with reference to the accompanying drawings.

[0037] The present invention discloses a dual-wire additive manufacturing gun based on cold cathode electron beam internal fused wire additive manufacturing, which employs the following device:

[0038] like Figure 1 As shown, it includes metal wire 1, wire feeding seal 2, anode 3, insulator 4, inner cathode 5, outer cathode 6, annular wire nozzle 7, discharge cavity 8, upper plate 9, air inlet pipe 10, outer cathode water inlet pipe 11, inner cathode water inlet pipe 12, inner cathode water outlet pipe 13, wire guide pipe 14, outer cathode water outlet pipe 15, and high voltage power supply 16.

[0039] The wire feed seal 2 is located on the upper part of the electron gun, and the wire feed seal 2 has a built-in cylindrical sealing rubber for sealing. The upper end of the wire feed seal 2 is connected to the wire feeding mechanism 19, and the lower end is connected to the wire guide tube 14. The wire guide tube 14 passes through the upper plate 9 and the insulator 4 and is threadedly connected to the annular thread nozzle 7 at its lower end. The wire guide tube 14 is equipped with annular sealing rings at the upper plate 9, the insulator 4, and the annular thread nozzle 7 for sealing. The anode 3 is located at the lower end of the upper plate 9 and is threadedly connected to it. The inner cathode 5 and the outer cathode 6 are coaxially mounted to form an electron beam emitting surface. Under the constraint of the annular thread nozzle 7 and the anode 3, the electron beam is emitted. The inner cathode 5 and the outer cathode 6 are located at the lower end of the insulator 5 and are detachably connected to it. The upper surfaces of the inner cathode 5 and the outer cathode 6 are... The cathode is water-cooled by a concave groove for deionized water to pass through. A high-voltage power line 17 is provided on the side of the inner cathode 5 and the outer cathode 6 to generate negative high voltage. The annular nozzle 7 is located between the inner cathode 5 and the outer cathode 6, and is located at the lower end of the insulator 5 and is detachably connected to it. The annular nozzle 7 is a tapered tubular structure that is wider at the top and narrower at the bottom. The insulator 5 is located inside the anode 3, above the inner cathode 5 and the outer cathode 6, and is coaxially mounted with the inner cathode 5 and has a predetermined withstand voltage strength. The insulator is connected to an air inlet pipe 10, an outer cathode water inlet pipe 11, an inner cathode water inlet pipe 12, an inner cathode water outlet pipe 13, a guide wire pipe 14, an outer cathode water outlet pipe 15, and a high-voltage power supply 16.

[0040] The metal wire 1 is fed sequentially from both sides of the dual-wire additive manufacturing gun body through the wire feeding mechanism 19 into the wire feeding seal 2, the wire guide tube 14, and the annular wire nozzle 7. The two types of wire are symmetrically distributed along the axis and fed at a fixed rate. When the two wires pass through the annular wire nozzle 7, they tilt at a certain angle towards the axis to ensure that the intersection of the two wires coincides with the focal point of the electron beam. The dual-wire feed rate is controlled by adjusting the G-language data in the industrial control computer to achieve alternating or simultaneous dual-wire additive manufacturing. Under vacuum conditions, working gas is first introduced into the electron gun through the gas supply device 20. Then, a 20-30kV high-voltage power supply 16 applies voltage between the inner cathode 5, outer cathode 6, anode 3, and annular wire nozzle 7 forming the discharge cavity 8. The generated electrons form an annular emission electron beam through the electron optical system established by the cathode and anode. On the worktable 22 inside the vacuum chamber 21, the cold cathode electron beam melts the metal wire at the electrostatic convergence point, i.e., the focal point. The molten metal wire is deposited layer by layer according to a predetermined trajectory, i.e., the edited G-language data, finally forming the shaped part 23.

[0041] The upper end face of the inner cathode 5 is connected to the inner cathode inlet 12 and the inner cathode outlet 13; the upper end face of the outer cathode 6 is connected to the outer cathode inlet 11 and the outer cathode outlet 15. The inner cathode 5 and the outer cathode 6 are connected to a high-voltage power line 17 on their sides. The outer cathode emits a main electron beam, and the inner cathode emits a secondary electron beam as a compensation beam to melt refractory metals.

[0042] The beam output of the dual-wire additive manufacturing gun based on cold cathode electron beam fused wire additive manufacturing presents an "X" shape. By adjusting the output power of the coaxial cold cathode electron gun, the wire feeding speed, the distance between the wire end and the workpiece, and the speed of the worktable, the molten droplets at the wire end can achieve free transition, "bridging" transition, and other modes for fused wire additive manufacturing.

[0043] The basic idea of ​​this invention is that the metal wires are sequentially fed into the wire feeding seal, wire guide tube, and annular nozzle from both sides of the dual-wire additive manufacturing gun via a wire feeding mechanism. Two types of wires are symmetrically distributed along the axis and fed at a fixed rate. When the two wires pass through the annular nozzle, they are tilted at a certain angle towards the axis to ensure that the intersection of the two wires coincides with the focal point of the electron beam. The dual-wire feed rate is controlled by adjusting the G-language data in the industrial control computer to achieve alternating or simultaneous dual-wire additive manufacturing. Under vacuum conditions, working gas is first introduced into the electron gun through a gas supply device. Then, a 20-30kV high-voltage power supply is applied between the inner cathode, outer cathode, anode, and annular nozzle to form a discharge cavity. The generated electrons form an annular emission electron beam through the electron optical system established by the cathode and anode. On the worktable inside the vacuum chamber, the cold cathode electron beam melts the metal wires at the electrostatic convergence point, i.e., the focal point. The molten metal wires are deposited layer by layer according to a predetermined trajectory, i.e., the edited G-language data, finally forming a shaped part.

[0044] Example

[0045] The first step is to inspect the gun body. Check if the gas hose is leaking air or the cooling water hose is leaking water. If there is any leakage, reconnect and secure the hoses. Check if the gun body mounting screws are secure to prevent air leaks. If they are loose, tighten them or replace the screws and sleeves. Check if there is any water on the high-voltage electrode. If so, wipe it dry.

[0046] The second step is to use a wire feeding device to feed the wire to about 20mm below the wire nozzle and then clamp the wire.

[0047] The third step is to move the workbench out (be careful to avoid the electron gun), place the substrate on it, secure the four corners of the substrate, and move the workbench into a suitable position in the room (be careful to avoid the electron gun), that is, the electron gun is above the substrate.

[0048] The fourth step is to close the vacuum chamber door and evacuate to a level below 1×10⁻¹, i.e., 10⁻². If the level cannot be evacuated to 10⁻², an airtightness check is performed.

[0049] Step 5: Click "Preheat" to preheat the electron gun. After preheating is complete, turn on the indoor lights and adjust the wire feeding position.

[0050] Step 6: Adjust the worktable so that the wire is aligned with the starting position of the substrate, and record the X, Y, and Z coordinates of the starting position.

[0051] Step 7: Enter the starting position to define the original coordinates of the additive manufacturing (0, 0), enter the G language (table additive manufacturing trajectory), and leave 30mm of movement space to prevent the table from hitting the electron gun.

[0052] Step 8: Turn on the gas flow meter, introduce gas, and stabilize the vacuum at a certain value.

[0053] Step 9: Turn on the power, record the beam current and high voltage values, adjust the gas flow rate, and scan the substrate for preheating after the beam stabilizes. Start additive manufacturing by clicking "Start" and using the knob to fine-tune the Z-axis position to achieve a bridging transition between the molten droplet and the substrate. On the worktable inside the vacuum chamber, the annular cold cathode electron beam melts the metal wire at the electrostatic convergence point, i.e., the focal point. The molten metal wire is deposited layer by layer along a predetermined trajectory, finally forming the shaped part.

[0054] Step 10: Turn off the power, turn off the gas flow meter, click "cooling," and release the gas after cooling is complete.

[0055] Step 11: Open the vacuum chamber and move the worktable out. Allow the formed part to cool down before proceeding with subsequent measurements, cutting, and mechanical property testing.

Claims

1. A dual-wire additive manufacturing gun body based on cold cathode electron beam in-situ fused wire additive manufacturing, characterized in that, It includes an anode (3), an insulator (4), an inner cathode (5), an outer cathode (6), an annular nozzle (7), a discharge cavity (8), an upper plate (9), a guide tube (14), a pipe for cooling the cathode, and a high-voltage power supply (16). The anode (3) is a shell composed of a cylindrical section and a conical section. The upper part of the cylindrical section of the anode is provided with a flange connected to the upper plate (9). An insulator (4) is provided inside the anode (3). An inner cathode (5) is provided in the middle of the lower end of the insulator. The outer cathode (6) is annular and connected to the lower part of the insulator. The insulator (4) is provided with a through hole for two wire guide tubes (14) to pass through, a water cooling channel, an air supply channel and a high voltage power supply channel. The annular wire nozzle (7) at the lower end of the insulator is a conical tube that is wider at the top and narrower at the bottom. The wall of the annular wire nozzle (7) is provided with a wire feeding channel that communicates with the wire guide tube. The connection position between the annular wire nozzle (7) and the insulator is located between the inner cathode and the outer cathode. The double wire feeding channel in the annular wire nozzle (7) makes the wire material passing through point to the focal point of the annular electron beam. A discharge cavity (8) is formed between the inner cathode (5), the outer cathode (6), the annular wire nozzle (7) and the lower part of the anode (3) shell. It also includes a wire feeding seal (2), the upper end of which is connected to the wire feeding mechanism (19), and the lower end is connected to the wire guide tube (14). The wire guide tube (14) passes through the upper plate (9) and the insulator (4) and is connected to the annular wire nozzle (7) at the lower end of the insulator. Both the inner and outer cathodes are provided with grooves for cooling water to pass through; The pipes for cooling the cathode include an outer cathode inlet pipe (11), an inner cathode inlet pipe (12), an inner cathode outlet pipe (13), and an outer cathode outlet pipe (15). Cooling water enters the sealed groove formed by the outer cathode and the insulator from the outer cathode inlet pipe (11). The cooling water in the groove enters the inner cathode inlet pipe (12) through the outer cathode outlet pipe (15) and the connecting pipe located on the upper plate, and then flows out through the inner cathode outlet pipe (13), thereby achieving cooling of the inner cathode and the outer cathode. Two guide tubes (14) are symmetrically arranged about the electron gun axis. The two guide tubes (14) are bent and connected between the upper plate (9) and the insulator (4) and a sealing ring is provided at the connection. The upper part of the guide tube (14) is parallel to the electron gun axis and the lower part points to the beam focus. The upper plate and the anode are connected by bolts, and both the inner cathode and the outer cathode are detachably connected to the insulator. A voltage of 20~30kV is applied between the inner cathode, outer cathode and anode, and the annular screw nozzle (7) is grounded; The upper end face of the annular screw nozzle (7) is provided with an air outlet groove (18), through which the gas inside and outside of the annular screw nozzle (7) is connected; The insulator (4) is coaxially mounted with the inner cathode (5), outer cathode (6), anode (3) and annular thread nozzle (7).

2. A dual-wire additive manufacturing gun system based on cold cathode electron beam in-situ fused wire additive manufacturing, characterized in that, Includes the dual-wire additive manufacturing gun body as described in claim 1.

3. The system according to claim 2, characterized in that, It also includes a wire feeding mechanism (19) and a worktable (22) located in the vacuum chamber (21); The metal wire is fed into the wire guide tube (14) through the wire feeding mechanism (19), and the forming part of the dual-wire additive manufacturing gun body is located in the vacuum chamber (21) and is formed in a vacuum environment.

4. A method for dual-filament additive manufacturing using the system described in claim 3, characterized in that, Includes the following steps: Step (1): Feed the wire to 20±2mm below the annular wire nozzle, clamp the wire, and the wire diameter shall not exceed 2mm; Step (2): Place the substrate on the worktable, clamp the four corners of the substrate, and push the worktable into the vacuum chamber so that the substrate is located below the electron gun. Step (3): Close the vacuum chamber door and evacuate to 1×10⁻⁶. -1 the following; Step (4): Preheat the electron gun; Step (5): Adjust the worktable so that the wire is aligned with the starting position of the substrate, and record the X, Y, and Z coordinates of the starting position; Step (6): Input the starting position to define the original coordinates of the additive manufacturing process (0, 0), and input the additive manufacturing trajectory of the worktable; Step (7): Turn on the gas flow meter, introduce gas into the vacuum chamber, and stabilize the vacuum level; Step (8): Turn on the power, record the beam current value and high voltage value, adjust the gas flow rate, and scan the substrate for preheating after the beam current stabilizes. Start additive manufacturing, and use the knob to fine-tune the Z-axis position so that the molten droplet and the substrate can achieve a bridging transition. On the worktable in the vacuum chamber, the annular cold cathode electron beam melts the metal wire at the electrostatic convergence position, i.e. the focal position. The molten metal wire is stacked layer by layer according to the predetermined trajectory, and finally forms a shaped part.

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