Negative pressure electric arc-laser beam composite cleaning machining method

Abstract

The invention discloses a negative-pressure electric arc-laser beam composite cleaning processing method, which is used for efficiently and nondestructively removing dense oxides and pollutants between layers of a metal additive component by utilizing a negative-pressure electric arc and laser cleaning time sequence synergistic process of an anti-gravity rotary suction effect generated by a magnetic confinement electric arc. The method is realized through a time sequence collaborative process and comprises the following steps of: firstly, pretreating an interlayer surface by using laser to vaporize or crush an oxide layer to form a microscopic concave-convex structure; then a longitudinal magnetic field is applied to generate a negative-pressure electric arc, an adsorption area is formed in the center of the electric arc, positive-pressure excavation of a traditional electric arc is converted into negative-pressure adsorption, and residues obtained after laser cleaning are sucked synchronously; and finally, the process is kept stable through dynamic cooperative control. The method solves the problem that compact oxides and pollutants on the surface of the additive manufacturing interlayer are difficult to efficiently and nondestructively remove, is suitable for removing complex pollutants between additive layers of aluminum alloy, titanium alloy, magnesium alloy and the like, and remarkably improves the surface quality and the dimensional precision of a component.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing post-processing, and specifically to a composite process for cleaning the interlayer surfaces of metal additive components, in particular to a time-series collaborative method combining negative pressure arc and laser cleaning, which is suitable for the efficient and non-destructive removal of dense oxides and contaminants in the additive manufacturing process of aluminum alloys, titanium alloys, magnesium alloys, etc. Background Art

[0002] Additive manufacturing forms complex components by layer-by-layer deposition, but dense oxides (such as Al2O3, TiO2) and pollutants (unmelted powder, carbides) are easily formed between layers, which significantly reduces the interlayer bonding strength, causes defects such as pores and cracks, and seriously damages the mechanical properties and dimensional accuracy of the components.

[0003] Traditional cleaning methods have significant limitations: mechanical / chemical methods (such as grinding, sandblasting or chemical cleaning) can easily damage the geometric accuracy of the substrate or pollute the environment, and it is difficult to completely remove microscopic oxides; in single-energy methods, laser cleaning is insufficient to remove deep and dense oxides, and high power can easily cause thermal damage to the substrate, while conventional arc cleaning relies on the "digging" effect of positive pressure, resulting in molten material splashing, causing secondary contamination and substrate deformation; in addition, the existing arc-laser beam composite cleaning process has low energy coupling efficiency due to the positive pressure arc characteristics, incomplete removal of molten material or semi-molten material, and lacks a precise action mechanism on the oxide layer-substrate interface, and it is still difficult to achieve both efficient removal and low damage goals.

[0004] Chinese patent application publication numbers CN117840134A and CN117960703A disclose a magnetic field-assisted laser cleaning device and method. Although the magnetic field acts on the laser-induced plasma plume to improve energy utilization, it does not directly act on the contaminants themselves (such as contaminants and residues). Such a passive action mechanism makes it difficult to actively remove high-adhesion contaminants between additive manufacturing layers, and the cleaning uniformity of curved workpieces is poor.

[0005] Chinese patent application publication number CN116727862A discloses a laser-arc hybrid cleaning method for aluminum alloy oxide films, which utilizes laser pretreatment combined with an arc cathode spot cleaning mechanism. While this technology can remove oxide films scattered on the surface, the positive pressure arc characteristics result in low energy coupling efficiency, incomplete removal of molten or semi-molten materials, and inability to remove deeply embedded contaminants between additive layers. Furthermore, the method relies on arc thermal evaporation to remove contaminants, essentially a thermodynamic cleaning mechanism that carries the risk of recondensation of molten contaminants.

[0006] Chinese patent application publication number CN113102390A discloses a method for cleaning micro- and nanoparticles using a magnetic field-confined dual-beam pulsed laser-induced shock wave. This method utilizes permanent magnets to enhance the intensity of the plasma shock wave. While this technology can increase the cleaning area, its static permanent magnetic field cannot dynamically adjust its intensity and direction. Furthermore, it is only suitable for cleaning micro- and nanoparticles on flat substrates and has limited effectiveness for stripping oxides from complex geometric cavities used in additive manufacturing.

[0007] Liu Mingxu. Numerical simulation of droplet transfer in short-circuit arc under magnetic field, 2015. Although this paper optimizes droplet transfer by generating an upward electromagnetic force component through a magnetic field, the overall arc pressure is downward, and it is still a positive pressure arc.

[0008] U.S. patent application publication number US2016 / 0067811A1 discloses a central negative pressure arc welding device and method. Although this method proposes the concept of "negative pressure arc", the technical essence still belongs to the category of positive pressure arc. The so-called "negative pressure" means that the pressure near the electrode is lower than the surrounding area. The arc force is still a downward positive pressure, and no adsorption force in the direction of anti-gravity is formed, which cannot achieve the suction and removal of pollutants.

[0009] To address the above-mentioned defects, the present invention proposes a phased cleaning strategy by coordinating the negative pressure arc with the anti-gravity rotation effect generated by the magnetic confinement arc and the laser timing: laser pretreatment + negative pressure arc adsorption stripping + dynamic collaborative control, to achieve efficient stripping of interlayer oxides and loose contaminants in additive manufacturing, and synchronously remove the molten or semi-molten residues generated by laser pretreatment by suction, to meet the complex working conditions of removing interlayer contaminants in additive components such as aluminum alloys, titanium alloys, and magnesium alloys. Summary of the Invention

[0010] The purpose of the present invention is to overcome the defects of the existing technology and provide a negative pressure arc-laser beam composite cleaning processing method, which utilizes the negative pressure arc and laser cleaning time-coordinated process of the anti-gravity rotation effect generated by the magnetic confinement arc to solve the problem of the difficulty in efficiently and non-destructively removing dense oxides and contaminants on the surface of the interlayers in additive manufacturing, ensure the precise external dimensions of the additive components and significantly improve their internal quality.

[0011] The above purpose is achieved through the following technical solutions:

[0012] The present invention provides a negative pressure arc-laser beam composite cleaning method, comprising the following steps:

[0013] Step 1: Pre-cleaning preparation: perform preliminary cleaning of the substrate to remove large loose debris, then fix the substrate on the workbench to ensure the additive working surface is flat, and perform single-pass multi-layer additive manufacturing with a layer thickness of 1.5-2mm;

[0014] Step 2: Adjust the relative positions of the laser generator and the negative pressure arc generator, and move the laser emitting device so that the laser spot is located directly above the interlayer surface to be cleaned and covers the area; at the same time, move the tungsten electrode of the negative pressure arc generator to the rear of the laser emitting device, so that it is away from the laser spot action area;

[0015] Step 3: Set the magnetic confinement arc parameters to generate a negative pressure arc. Apply an excitation current to the excitation coil on the cleaning equipment to generate a longitudinal magnetic field that coincides with or is parallel to the arc's central axis, thereby forming a negative pressure arc vortex suction flow field. The arc current range is 60 to 300 A, the arc magnetic field intensity range is 0.023 to 0.08 T, and a negative pressure of -165 to -800 Pa is formed at the arc center. The affected area of ​​the negative pressure arc is 2.4 to 30 mm, the arc frequency range is 12 to 100 Hz, the arc duty cycle is 10% to 30%, and the magnetic field threshold range for the negative pressure arc is 0.022 to 0.037 T.

[0016] Step 4: Set the laser pretreatment parameters. The laser scanning path follows the single-pass deposition direction during additive manufacturing. The laser preferentially acts on the surface of the interlayer contaminants, using the photothermal effect to vaporize or break up the dense oxide layer, forming a microscopic concave-convex structure to enhance the local electric field strength.

[0017] Step 5: Start additive manufacturing and execute the three stages of the sequential collaborative cleaning process. 1) Laser pretreatment stage: Turn on the laser and act on the dense oxide and contaminant surface between the aluminum alloy additive manufacturing layers according to the set parameters, so that the oxide layer is initially vaporized and broken, forming a microscopic concave-convex structure that is conducive to negative pressure arc adsorption. 2) Negative pressure arc adsorption and stripping stage: Activate the negative pressure arc 7 that generates the anti-gravity vortex suction effect generated by the magnetic confinement arc. Utilize the anti-gravity vortex suction effect generated by the magnetic confinement arc to transform the excavation effect of the conventional positive pressure arc into the adsorption effect of the negative pressure arc, achieving efficient stripping of the oxide and loose contaminants between the additive manufacturing layers, and simultaneously remove the molten or semi-molten residues generated by the laser pretreatment by suction, reducing the surface roughness and enhancing its surface wear resistance. 3) Dynamic collaborative control stage: During the laser and arc collaborative cleaning process, the scanning speed ratio of the laser to the arc beam is 1:1 to 1:3, and the controller is used to fine-tune the electrode positive connection (EP) ratio in real time between 5% and 50% to ensure the cleaning effect of the arc negative pressure.

[0018] In particular, the magnetic field threshold and the arc current satisfy the following functional relationship:

[0019] B(I)=0.018+3.35×10 -5 I+1.25×10 -7 I 2

[0020] Where: B represents the magnetic field threshold, the unit is Tesla (T), I represents the arc current, the unit is Ampere (A);

[0021] Furthermore, the arc parameters in step 3, in addition to the parameters described above, also include a tungsten electrode diameter of 0.8 to 2.4 mm, an arc length of 3 to 20 mm, an arc voltage of 10 to 50 V, a cleaning speed of 50 to 200 cm / min, a shielding gas flow rate of 15 to 40 L / min, and the shielding gas is 99.99% argon, 99.99% helium, or a mixture of argon and helium;

[0022] Furthermore, the cleaning equipment in step 3 includes a nozzle or a gun body, an excitation coil and a water-cooling structure; the excitation coil is a spiral hollow coil with a built-in iron core and a water-cooling structure, and is integrated with the nozzle or the gun body into an integrated structure; the excitation current has an adjustable waveform (DC or AC or pulse or variable polarity waveform), frequency and amplitude to generate a longitudinal magnetic field adapted to the laser cleaning parameters; the longitudinal magnetic field is a gap alternating longitudinal magnetic field, or a constant longitudinal magnetic field, or a pulsed longitudinal magnetic field, or a sinusoidal longitudinal magnetic field, or an alternating longitudinal magnetic field;

[0023] Furthermore, the arc current in step 3 is a gap alternating current, or a constant current, or a pulse current, or a sinusoidal current, or an alternating current, or a variable polarity current;

[0024] Furthermore, the arc parameters in step 3 are set to adapt the negative pressure arc magnetic field process parameters for different materials. When cleaning aluminum alloy, the electrode positive connection (EP) accounts for 38% to 50%, and the magnetic field strength ranges from 0.023 to 0.045 T; when cleaning titanium alloy, the electrode positive connection (EP) accounts for 30% to 35%, and the magnetic field strength is 0.023 to 0.05 T; when cleaning magnesium alloy, the electrode positive connection (EP) accounts for 5% to 25%, and the magnetic field strength is 0.023 to 0.068 T;

[0025] Furthermore, the laser in step 4 is a pulsed laser or a continuous laser, and the laser power is adapted to the light and heat absorption characteristics of the material to be cleaned. The laser power for cleaning aluminum alloy is 20-200W, the laser power for cleaning titanium alloy is 80-200W, and the laser power for cleaning magnesium alloy is 20-150W.

[0026] Furthermore, the laser pretreatment in step 4 is to monitor the oxide layer thickness in real time by a laser interferometer. When the thickness is greater than 50 μm, the scanning speed ratio of the laser and arc beam is dynamically adjusted to 1:2 to 1:3, so as to achieve low-speed laser deep processing and high-speed arc cleaning. The substrate temperature is monitored in real time by an infrared thermal imager to ensure that the fluctuation is less than 5°C.

[0027] Furthermore, the controller in step 5 is a proportional-integral-derivative (PID) controller, or a microcomputer, or a programmable logic controller (PLC), or a fuzzy logic controller, or a model predictive controller (MPC), or an adaptive controller;

[0028] Furthermore, the equipment of the negative pressure arc-laser beam composite cleaning processing method requires regular maintenance. The laser energy density is calibrated every 100 to 200 cumulative working hours, and the calibration error is controlled within ±3%; the electrode is replaced every 200 hours, and the electrode wear is controlled to <0.2mm. When the current is >150A, the electrode replacement cycle is shortened to 150 hours, and the wear threshold is adjusted to <0.15mm.

[0029] The beneficial effects of the present invention include:

[0030] The negative-pressure arc, leveraging the anti-gravity spin-attraction effect generated by the magnetically confined arc, acts directly on the interface between the oxide film and the substrate, physically stripping away contaminants. Compared to the excavation effect of a conventional positive-pressure arc, the negative-pressure arc's adsorption force opposes the direction of gravity, drawing molten or semi-molten additive manufacturing interlayer oxides and contaminants into the negative-pressure zone for centralized treatment, avoiding secondary contamination caused by falling spatter from the molten pool.

[0031] Through the sequential coordination of laser pretreatment and negative pressure arc adsorption stripping, the laser preferentially acts on the surface of the oxide layer, vaporizing or shattering it and forming a microscopic electric field enhancement structure, guiding the subsequent arc cathode spots to precisely concentrate in the residual oxidation area. The negative pressure arc is then activated, using its anti-gravity adsorption force to efficiently strip away contaminants from the surface of the molten pool and simultaneously remove the molten or semi-molten residues generated by the laser by suction. Compared to single laser or arc cleaning, this collaborative process overcomes the limitation of laser's inefficient removal of deep, dense oxides while avoiding the thermal damage that a single arc may cause to the substrate, achieving efficient, precise, and low-damage integrated removal of complex contaminants between additive layers.

[0032] In order to better demonstrate the implementation process, functional characteristics and advantages of the present invention, embodiments will be used below and further explained in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the principle of a negative pressure arc-laser beam composite cleaning method of the present invention;

[0034] Figure 2 Schematic diagram comparing the adsorption effect of the negative pressure arc and the excavation effect of the positive pressure arc of the present invention, wherein (a) is a schematic diagram of the adsorption effect of the negative pressure arc, and (b) is a schematic diagram of the excavation effect of the positive pressure arc;

[0035] Figure 3is a relationship diagram between the magnetic field threshold and arc current of the negative pressure arc of the present invention;

[0036] Among them, 1-laser beam, 2-additive device, 3-deposited layer, 4-tungsten electrode, 5-excitation coil, 6-anti-gravity spin effect, 7-negative pressure arc, 8-interlayer contaminants, 9-substrate, 10-positive pressure arc;

[0037] Figure 4 This is the temperature field of the negative pressure arc of the present invention. In the figure, the currents (a)-(f) are (a) 160A, (b) 180A, (c) 200A, (d) 220A, (e) 240A, and (f) 260A respectively. DETAILED DESCRIPTION

[0038] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0039] The following combination Figure 1 and Figure 2 The present invention describes a negative pressure arc-laser beam composite cleaning process. This method utilizes the anti-gravity vortex suction effect of a magnetically confined arc to combine with laser cleaning to solve the problem of efficient and non-destructive removal of dense oxides and contaminants on the interlayer surfaces of additive manufacturing. This method ensures the precise dimensions of additive components and significantly improves their internal quality. Specifically, it includes the following steps:

[0040] Step 1: Preparation before cleaning;

[0041] Step 2: Adjust the relative positions of the laser generating device and the negative pressure arc generating device;

[0042] Step 3: Set the magnetic confinement arc parameters to generate a negative pressure arc;

[0043] Step 4: Set laser preprocessing parameters;

[0044] Step 5: Start additive manufacturing of 5051 aluminum alloy and perform three stages of the sequential co-cleaning process.

[0045] like Figure 1As shown, during the additive manufacturing process, the substrate 9 is first fixed and preliminarily cleaned. The additive device, laser spot, and negative pressure arc tungsten electrode are adjusted to be on the same path, so that the laser spot is located behind the additive device and the tungsten electrode 4 is located behind the laser spot. The magnetic confinement arc parameters are set, the arc current range is 60 to 300A, an excitation coil 5 is set on the tungsten electrode 4, and an excitation current is applied to generate a longitudinal magnetic field that coincides with or is parallel to the arc center axis. The magnetic field intensity range is between 0.023 and 0.08T, the arc frequency range is 12 to 100Hz, the arc duty cycle is 10% to 30%, and the magnetic field threshold range of the negative pressure arc is 0.022 to 0.037T. This forms a negative pressure arc with an anti-gravity vortex suction effect, forming a negative pressure of -165 to -800Pa at the arc center, and the diameter of the negative pressure arc affected area is 2.4 to 30mm. The laser pretreatment parameters are set, and the laser scanning path follows the single-pass deposition direction during additive manufacturing. The photothermal effect is used to vaporize or break up the dense oxide layer, forming a microscopic concave-convex structure to enhance the local electric field. Finally, the three stages of the sequential collaborative cleaning process are executed: 1) Laser pretreatment stage: The laser breaks up the oxide layer to form a structure that is conducive to adsorption; 2) Negative pressure arc adsorption and stripping stage: The anti-gravity vortex suction effect generated by the magnetic confinement arc is used to transform the conventional positive pressure excavation effect into a negative pressure adsorption effect, efficiently stripping oxides and loose contaminants, and simultaneously sucking out laser-generated residues to reduce surface roughness; 3) Dynamic collaborative control stage: The scanning speed ratio of the laser to the arc beam is 1:1 to 1:3, and the electrode positive connection (EP) ratio is fine-tuned in real time by the controller to 5% to 50% to ensure the cleaning effect of the negative arc pressure.

[0046] In particular, the corresponding relationship between the magnetic field threshold and the arc current is as follows: Figure 3 As shown, and satisfies the following functional relationship:

[0047] B(I)=0.018+3.35×10 -5 I+1.25×10 -7 I 2

[0048] Where: B represents the magnetic field threshold, the unit is Tesla (T), I represents the arc current, the unit is Ampere (A);

[0049] The arc parameters in step 3, in addition to the parameters described above, also include a tungsten electrode diameter of 0.8 to 2.4 mm, an arc length of 3 to 20 mm, an arc voltage of 10 to 50 V, a cleaning speed of 50 to 200 cm / min, a shielding gas flow rate of 15 to 40 L / min, and the shielding gas is 99.99% argon, 99.99% helium, or a mixture of argon and helium.

[0050] The cleaning equipment in step 3 includes a nozzle or gun body, an excitation coil and a water-cooling structure; the excitation coil is a spiral hollow coil with a built-in iron core and a water-cooling structure, and is integrated with the nozzle or gun body into an integrated structure; the excitation current is an adjustable waveform (DC or AC or pulse or variable polarity waveform), frequency and amplitude to generate a longitudinal magnetic field adapted to the laser cleaning parameters; the longitudinal magnetic field is a gap alternating longitudinal magnetic field, or a constant longitudinal magnetic field, or a pulsed longitudinal magnetic field, or a sinusoidal longitudinal magnetic field, or an alternating longitudinal magnetic field.

[0051] The arc current in step 3 is a gap alternating current, a constant current, a pulse current, a sinusoidal current, an alternating current, or a variable polarity current.

[0052] The arc parameters in step 3 are set to adapt the negative pressure arc magnetic field process parameters for different materials. When cleaning aluminum alloy, the electrode positive connection (EP) accounts for 38% to 50%, and the magnetic field strength ranges from 0.023 to 0.045T; when cleaning titanium alloy, the electrode positive connection (EP) accounts for 30% to 35%, and the magnetic field strength is 0.023 to 0.05T; when cleaning magnesium alloy, the electrode positive connection (EP) accounts for 5% to 25%, and the magnetic field strength is 0.023 to 0.068T.

[0053] The laser in step 4 is a pulsed laser or a continuous laser, and the laser power is adapted to the light and heat absorption characteristics of the material to be cleaned. The laser power for cleaning aluminum alloy is 20-200w, the laser power for cleaning titanium alloy is 80-200w, and the laser power for cleaning magnesium alloy is 20-150w.

[0054] The laser pretreatment in step 4 is to monitor the oxide layer thickness in real time by a laser interferometer. When the thickness is greater than 50 μm, the scanning speed ratio of the laser and arc beam is dynamically adjusted to 1:2 to 1:3 to achieve low-speed laser deep processing and high-speed arc cleaning. The substrate temperature is monitored in real time by an infrared thermal imager to ensure that the fluctuation is less than 5°C.

[0055] The controller in step 5 is a proportional-integral-derivative (PID) controller, or a microcomputer, or a programmable logic controller (PLC), or a fuzzy logic controller, or a model predictive controller (MPC), or an adaptive controller.

[0056] The equipment of the negative pressure arc-laser beam composite cleaning processing method requires regular maintenance. The laser energy density is calibrated every 100 to 200 cumulative working hours, and the calibration error is controlled within ±3%. The electrode is replaced every 200 hours, and the electrode wear is controlled to be less than 0.2 mm. When the current is greater than 150 A, the electrode replacement cycle is shortened to 150 hours, and the wear threshold is adjusted to less than 0.15 mm.

[0057] Example 1

[0058] The present embodiment provides a method for vacuum arc-laser beam composite cleaning of 5051 aluminum alloy additively manufactured parts, specifically comprising the following steps:

[0059] Step 1: Cleaning Preparation: Initially clean the 5051 aluminum alloy substrate to remove any loose debris. Then, secure the substrate to a workbench to ensure a flat surface for additive manufacturing. Perform single-pass, multi-layer additive manufacturing of the aluminum alloy with a layer thickness of 2 mm.

[0060] Step 2: Adjust the relative positions of the laser generator and the negative pressure arc generator. Move the laser emitting device so that the laser spot is directly above and covers the interlayer surface to be cleaned. Simultaneously, move the tungsten electrode of the negative pressure arc generator behind the laser emitting device, away from the laser spot area.

[0061] Step 3: Set the magnetic confinement arc parameters to generate a negative pressure arc. The tungsten pole diameter is 0.8mm, the arc length is 3mm, and an excitation current is applied to the excitation coil on the cleaning equipment to generate a longitudinal magnetic field parallel to the arc center axis, thereby forming a negative pressure arc vortex suction flow field. The current is 60A, and the critical magnetic field strength threshold for the formation of arc negative pressure is 0.022T. A longitudinal magnetic field with a magnetic field strength of 0.042T is applied, resulting in a negative pressure of -165Pa at the center of the arc and a negative pressure arc influence area with a diameter of 2.4mm.

[0062] Step 4: Set the laser pretreatment parameters. A pulsed laser with a power of 200W was used. The laser scanning path followed the single-pass deposition direction used in additive manufacturing. The laser preferentially targeted the surface of interlayer contaminants, utilizing the photothermal effect to vaporize or fragment the dense oxide layer, forming a microscopic concave-convex structure that enhanced the local electric field strength.

[0063] Step 5, start the additive manufacturing of 5051 aluminum alloy and perform the three stages of the sequential collaborative cleaning process: 1) Laser pretreatment stage: Turn on the laser and act on the dense oxide and contaminant surface between the aluminum alloy additive manufacturing layers according to the set parameters to initially vaporize and break the oxide layer, forming a micro-concave and convex structure that is conducive to negative pressure arc adsorption. 2) Negative pressure arc adsorption and stripping stage: Apply a longitudinal magnetic field to generate an anti-gravity spin suction effect 6, thereby generating a negative pressure arc 7, using Figure 1The anti-gravity vortex suction effect generated by the magnetically confined arc (shown) transforms the excavation action of the conventional positive-pressure arc 10 into the adsorption action of the negative-pressure arc 7, achieving efficient stripping of interlayer oxides and loose contaminants in additive manufacturing. It also simultaneously removes molten or semi-molten residues from laser pretreatment by suction, reducing surface roughness by 10%-15% and enhancing surface wear resistance. 3) Dynamic Cooperative Control Stage: During the laser and arc collaborative cleaning process, the scanning speed ratio of the laser to the arc beam is 1:1. The controller fine-tunes the electrode positive contact (EP) ratio to 38%-50% in real time to ensure the cleaning effect of the negative arc pressure.

[0064] Example 2

[0065] The present embodiment provides a method for vacuum arc-laser beam composite cleaning of a Ti-6Al-4V titanium alloy additively manufactured part, specifically comprising the following steps:

[0066] Step 1: Cleaning Preparation: The Ti-6Al-4V titanium alloy substrate is initially cleaned to remove large loose debris. The substrate is then secured to a workbench to ensure a flat surface for additive manufacturing. Single-pass, multi-layer additive manufacturing of aluminum alloy is performed, with a layer thickness of 1.5 mm.

[0067] Step 2: Adjust the relative positions of the laser generator and the negative pressure arc generator. Move the laser emitting device so that the laser spot is directly above and covers the interlayer surface to be cleaned. Simultaneously, move the tungsten electrode of the negative pressure arc generator behind the laser emitting device, away from the laser spot area.

[0068] Step 3: Set the magnetic confinement arc parameters to generate a negative pressure arc. The tungsten pole diameter is 1.2mm, the arc length is 5mm, and an excitation current is applied to the excitation coil on the cleaning equipment to generate a longitudinal magnetic field parallel to the arc center axis, thereby forming a negative pressure arc vortex suction flow field. The current is 140A, and the critical magnetic field strength threshold for arc negative pressure is 0.025T. A longitudinal magnetic field with a magnetic field strength of 0.048T is applied, resulting in a negative pressure of -400Pa at the center of the arc and a 15mm negative pressure arc influence area.

[0069] Step 4: Set the laser pretreatment parameters. A pulsed laser with a power of 180W was selected. The laser scanning path followed the single-pass deposition direction used in additive manufacturing. The laser preferentially targeted the surface of the interlayer contaminants, utilizing the photothermal effect to vaporize or fragment the dense oxide layer, forming a microscopic concave-convex structure that enhanced the local electric field strength.

[0070] Step 5, start the additive manufacturing of Ti-6Al-4V titanium alloy and perform the three stages of the sequential collaborative cleaning process. 1) Laser pretreatment stage: Turn on the laser and act on the dense oxide and contaminant surface between the aluminum alloy additive manufacturing layers according to the set parameters to initially vaporize and break the oxide layer, forming a micro-concave and convex structure that is conducive to negative pressure arc adsorption. 2) Negative pressure arc adsorption and stripping stage: Apply a longitudinal magnetic field to generate an anti-gravity spin suction effect 6, thereby generating a negative pressure arc 7, using Figure 1 The anti-gravity vortex suction effect generated by the magnetically confined arc (shown) transforms the excavation action of the conventional positive-pressure arc 10 into the adsorption action of the negative-pressure arc 7, achieving efficient stripping of interlayer oxides and loose contaminants in additive manufacturing. It also simultaneously removes molten or semi-molten residues from laser pretreatment by suction, reducing surface roughness by 15%-25% and enhancing surface wear resistance. 3) Dynamic Cooperative Control Phase: During the laser and arc collaborative cleaning process, the scanning speed ratio of the laser to arc beam is 1:1.8. The controller fine-tunes the electrode positive contact (EP) ratio to 30%-35% in real time to ensure the cleaning effect of the negative arc pressure.

[0071] Example 3

[0072] The present embodiment provides a method for vacuum arc-laser beam composite cleaning of AZ31 magnesium alloy additively manufactured parts, specifically comprising the following steps:

[0073] Step 1: Cleaning Preparation: The AZ31 magnesium alloy substrate is initially cleaned to remove large loose debris. The substrate is then secured to a workbench to ensure a flat surface for additive manufacturing. Single-pass, multi-layer additive manufacturing of aluminum alloy is performed, with a layer thickness of 1.8 mm.

[0074] Step 2: Adjust the relative positions of the laser generator and the negative pressure arc generator. Move the laser emitting device so that the laser spot is directly above and covers the interlayer surface to be cleaned. Simultaneously, move the tungsten electrode of the negative pressure arc generator behind the laser emitting device, away from the laser spot area.

[0075] Step 3: Set the magnetic confinement arc parameters to generate a negative pressure arc. The tungsten pole diameter is 2mm, the arc length is 15mm, and an excitation current is applied to the excitation coil on the cleaning equipment to generate a longitudinal magnetic field parallel to the arc center axis, thereby forming a negative pressure arc vortex suction flow field. The current is 300A, and the critical magnetic field strength threshold for arc negative pressure is 0.037T. A longitudinal magnetic field with a magnetic field strength of 0.08T is applied, resulting in a negative pressure of -800Pa at the center of the arc and a 30mm negative pressure arc influence area.

[0076] Step 4: Set the laser pretreatment parameters. A pulsed laser with a power of 120W was selected. The laser scanning path followed the single-pass deposition direction used in additive manufacturing. The laser preferentially targeted the surface of the interlayer contaminants, utilizing the photothermal effect to vaporize or fragment the dense oxide layer, forming a microscopic concave-convex structure that enhanced the local electric field strength.

[0077] Step 5, start the additive manufacturing of AZ31 magnesium alloy and perform the three process stages of the sequential collaborative cleaning process. 1) Laser pretreatment stage: Turn on the laser and act on the dense oxide and contaminant surface between the aluminum alloy additive manufacturing layers according to the set parameters to initially vaporize and break the oxide layer, forming a micro-concave and convex structure that is conducive to negative pressure arc adsorption. 2) Negative pressure arc adsorption and stripping stage: Apply a longitudinal magnetic field to generate an anti-gravity spin suction effect 6, thereby generating a negative pressure arc 7, using Figure 1 The anti-gravity vortex suction effect generated by the magnetically confined arc (shown) transforms the excavation action of the conventional positive-pressure arc 10 into the adsorption action of the negative-pressure arc 7, achieving efficient stripping of interlayer oxides and loose contaminants in additive manufacturing. It also simultaneously removes molten or semi-molten residues from laser pretreatment by suction, reducing surface roughness by 10%-20% and enhancing surface wear resistance. 3) Dynamic Cooperative Control Phase: During the laser and arc collaborative cleaning process, the scanning speed ratio of the laser to arc beam is 1:3. The controller fine-tunes the electrode positive contact (EP) ratio to 5%-25% in real time to ensure the cleaning effect of the negative arc pressure.

[0078] It should be noted that the above embodiments are intended only to illustrate the technical principles of the present invention and are not intended to limit the scope of protection. Those skilled in the art may, without departing from the core concept of the present invention, make adaptive modifications or equivalent substitutions to the technical solutions, and such modifications and improvements shall fall within the scope of protection defined in the claims.

Claims

1. A negative pressure arc-laser beam composite cleaning method, characterized in that: The sequential synergistic process of negative pressure arc and laser cleaning, which utilizes the anti-gravity swirl effect generated by the magnetic confinement arc, solves the problem of efficient and non-destructive removal of dense oxides and contaminants on the surface between additive manufacturing layers, ensuring the precise external dimensions of additive components and significantly improving their internal quality. The negative pressure arc with anti-gravity vortex suction effect is constructed by: arranging an excitation coil on the cleaning device, applying an excitation current to generate a longitudinal magnetic field that is coincident with or parallel to the arc center axis; dynamically adjusting the longitudinal magnetic field strength to exceed a critical threshold for arc negative pressure formation, so that a negative pressure of -165 to -800 Pa is formed at the arc center, and the diameter of the negative pressure arc affected area is 2.4 to 30 mm; The sequential coordinated process of negative pressure arc and laser cleaning is performed in the following stages: (1) Laser pretreatment stage: The laser preferentially acts on the surface of the pollutant, using the photothermal effect to vaporize or break the dense oxide layer, forming a microscopic concave-convex structure to enhance the local electric field strength and guide the subsequent arc cathode spots to accurately gather in the residual oxidation area; (2) Negative pressure arc adsorption and stripping stage: Activate the negative pressure arc with the anti-gravity rotation effect generated by the magnetic confinement arc, and use its strong adsorption force in the anti-gravity direction to efficiently strip the surface oxides and loose contaminants of the molten pool, and simultaneously remove the molten or semi-molten residues generated by the laser pretreatment by suction; (3) Dynamic collaborative control stage: The scanning speed ratio of the laser and arc beams is 1:1 to 1:3, and the electrode positive connection (EP) ratio is fine-tuned in real time by the controller to 5% to 50% to ensure the cleaning effect of the arc negative pressure; The process parameters of the negative pressure arc-laser beam composite cleaning method are as follows: arc current range is 60-300A, arc magnetic field intensity range is 0.023-0.08T, arc frequency range is 12-100Hz, arc duty cycle is 10%-30%, and negative pressure arc magnetic field threshold range is 0.022-0.037T; The magnetic field threshold and arc current satisfy the following functional relationship: B(I)=0.018+3.35×10 -5 ·I+1.25×10 -7 ·I 2 Where: B represents the magnetic field threshold, the unit is Tesla (T), I represents the arc current, the unit is Ampere (A).

2. The negative pressure arc-laser beam composite cleaning method according to claim 1, characterized in that: The tungsten electrode diameter is 0.8-2.4mm, the arc length is 3-20mm, the arc voltage is 10-50V, the cleaning speed is 50-200cm / min, the shielding gas flow is 15-40L / min, and the shielding gas is 99.99% argon, 99.99% helium, or a mixture of argon and helium; the laser cleaning system uses pulsed laser or continuous laser, and the laser power is adapted to the light and heat absorption characteristics of the material being cleaned.

3. The negative pressure arc-laser beam composite cleaning method according to claim 1, characterized in that: The cleaning equipment includes a nozzle or gun body, an excitation coil and a water-cooling structure; the excitation coil is a spiral hollow coil with a built-in iron core and a water-cooling structure, and is integrated with the nozzle or gun body into an integrated structure; the adjustable waveform of the excitation current is a DC or AC or pulse or variable polarity waveform, with adjustable frequency and amplitude to generate a longitudinal magnetic field adapted to the laser cleaning parameters; the longitudinal magnetic field is one of a gap alternating longitudinal magnetic field, a constant longitudinal magnetic field, a pulsed longitudinal magnetic field, a sinusoidal wave longitudinal magnetic field, and an alternating longitudinal magnetic field.

4. The negative pressure arc-laser beam composite cleaning method according to claim 1, characterized in that: The current is one of intermittent alternating current, constant current, pulse current, sinusoidal current, alternating current, and variable polarity current.

5. The negative pressure arc-laser beam composite cleaning method according to claim 1, characterized in that: Adapt the negative pressure arc magnetic field process parameters to different materials. When cleaning aluminum alloy, the electrode positive connection (EP) accounts for 38% to 50%, and the magnetic field strength ranges from 0.023 to 0.045T; when cleaning titanium alloy, the electrode positive connection (EP) accounts for 30% to 35%, and the magnetic field strength is 0.023 to 0.05T; when cleaning magnesium alloy, the electrode positive connection (EP) accounts for 5% to 25%, and the magnetic field strength is 0.023 to 0.068T.

6. The negative pressure arc-laser beam composite cleaning method according to claim 1, characterized in that: The thickness of the oxide layer is monitored in real time by a laser interferometer. When the thickness is greater than 50 μm, the scanning speed ratio of the laser and arc beam is dynamically adjusted to 1:2 to 1:3, achieving low-speed deep processing by laser and high-speed cleaning by arc. The substrate temperature is monitored in real time by an infrared thermal imager to ensure that the fluctuation is less than 5°C.

7. The negative pressure arc-laser beam composite cleaning method according to claim 1, characterized in that: Set maintenance cycle parameters: calibrate the laser energy density every 100 to 200 cumulative working hours, and control the calibration error within ±3%; replace the electrode every 200 hours, and control the electrode wear to <0.2mm. When the current is >150A, the electrode replacement cycle is shortened to 150 hours, and the wear threshold is adjusted to <0.15mm.

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