Device and method for inhibiting laser deposition repairing smoke dust of magnesium alloy part

Abstract

The invention relates to the technical field of laser deposition manufacturing, in particular to a device and method for inhibiting magnesium alloy part laser deposition repairing smoke dust, the device comprises a box body, a workbench used for containing parts is arranged at the bottom in the box body, and a water cooling device used for cooling the parts is arranged on the top face of the workbench; an ultrasonic vibration device used for providing disturbance for the molten pool is arranged below the workbench, and an infrared temperature measurement sensor used for monitoring the temperature of the parts is arranged at the top in the box body; the two sides of the box body communicate with a pressurizing gas inlet device used for supplying gas into the box body and a waste gas treatment device used for removing dust in the box body correspondingly. The ultrasonic vibration device provides disturbance for the molten pool, the water cooling device forcibly cools parts, and the waste gas treatment device removes dust in the box body; by means of the method, smoke dust can be effectively restrained in the magnesium alloy laser repairing process, forming defects can be effectively reduced, and the mechanical performance is improved.

Description

Technical Field

[0001] This invention relates to the field of laser deposition manufacturing technology, and in particular to an apparatus and method for suppressing dust from laser deposition repair of magnesium alloy parts. Background Technology

[0002] Magnesium alloys, as a highly promising lightweight metal material, have been widely used in aerospace, automotive, 3C electronics and biomedical fields due to their low density, high specific strength, good vibration damping and absorption performance and excellent electromagnetic shielding ability; in addition, magnesium alloys also have good casting performance and recyclability.

[0003] Laser deposition manufacturing is based on the "discrete / accumulated forming" concept of additive manufacturing. Using a laser as a heat source, metal powder or filament materials are fed into a laser molten pool and melted, solidified and deposited layer by layer according to the slicing procedure of the three-dimensional model to form complex metal components.

[0004] Mg has a low boiling point (approximately 1091℃) and a high saturated vapor pressure (0.13 kPa at 620℃, which increases significantly to 51 kPa at 1027℃). This leads to elemental evaporation during laser deposition repair, resulting in severe spatter and significant dust. The dust consists of a mixture of metal vapor above the molten pool, plasma, oxides (despite the presence of a protective gas, magnesium is easily oxidized, generating a large amount of oxides during laser deposition repair of magnesium alloys), and fine particles of condensed vapor. The dust generated during the laser deposition repair of magnesium alloys not only affects the observation of the formed parts during processing but also leads to changes in the composition of the formed parts and the generation of various defects, ultimately affecting mechanical properties.

[0005] Furthermore, the fumes generated during the laser deposition repair of magnesium alloys are considered a significant cause of many defects. When magnesium alloy powder comes into contact with a high-energy-density laser, fumes are produced. The evaporated gases rapidly expand and escape into the environment, creating plumes that generate significant back pressure on the molten pool. On one hand, the evaporation plumes blow powder away from the molten pool, affecting the processing rate. They also cause molten pool spatter, leading to spheroidization defects. Small particles in the vapor scatter the laser beam and splash onto the transmission mirror, hindering laser beam propagation and causing instability in the melting process. Turbulence forms in the molten pool, trapping the protective gas. As the molten pool solidifies, the protective gas that fails to escape forms porosity defects in the forming area. On the other hand, the back pressure acts on the molten pool surface, counteracting surface tension and creating narrow, deep, elongated cavities within the molten pool. Molten pool instability and cavity necking form a closed cavity, ultimately creating a keyhole. Additionally, vaporized elements diffuse from the molten pool to its surface and then evaporate into the protective gas environment. Due to the rapid cooling of the molten pool, the magnesium vapor that fails to escape also forms porosity defects upon cooling.

[0006] The generation of smoke and dust can reduce the magnesium content in the molded parts, causing the chemical composition to deviate from the design value, which in turn affects the uniformity of the microstructure. At the same time, a large number of pore defects reduce the density of the molded parts, becoming stress concentration points and significantly weakening the mechanical properties of the molded parts, such as tensile strength and hardness.

[0007] Therefore, there is an urgent need for a device and method to suppress the generation of fumes during laser deposition repair of magnesium alloy parts, which can not only effectively reduce the generation of fumes during the laser deposition repair process, but also effectively reduce the generation of forming defects and improve mechanical properties. Summary of the Invention

[0008] The purpose of this invention is to provide an apparatus and method for suppressing the smoke and dust generated during laser deposition repair of magnesium alloy parts, so as to solve the problems existing in the prior art.

[0009] To achieve the above objectives, the present invention provides the following solution: a device for suppressing dust from laser deposition repair of magnesium alloy parts, comprising a housing, a worktable for placing parts is provided at the bottom of the housing, a water cooling device for cooling the parts is provided on the top surface of the worktable, an ultrasonic vibration device for providing disturbance to the molten pool is provided below the worktable, and an infrared temperature sensor for monitoring the temperature of the parts is provided at the top of the housing; a pressurized air intake device for supplying air into the housing and a waste gas treatment device for removing dust from the housing are respectively connected to both sides of the housing.

[0010] Preferably, the upper and lower parts of the housing facing the pressurized air intake device are respectively provided with air inlets, and the air inlets are connected to the air supply end of the pressurized air intake device.

[0011] Preferably, the upper and lower parts of the housing facing the waste gas treatment device are respectively provided with air outlets, and the air outlets are connected to the air inlet of the waste gas treatment device.

[0012] Preferably, a one-way control valve is installed in the air inlet and the air outlet respectively.

[0013] Preferably, the pressurized air intake device is fixedly connected with a first air intake pipe and a second air intake pipe, the first air intake pipe being connected to the upper air intake port, and the second air intake pipe being connected to the lower air intake port.

[0014] Preferably, the waste gas treatment device is fixedly connected with a first exhaust pipe and a second exhaust pipe, the first exhaust pipe being connected to the upper exhaust port and the second exhaust pipe being connected to the lower exhaust port.

[0015] Preferably, the workbench is provided with a water inlet and a water outlet on both sides, and the water inlet and the water outlet are located on the box body.

[0016] Preferably, the water cooling device includes a cooling pipe embedded in the top surface of the workbench, with both ends of the cooling pipe extending out of the box body through the water inlet and the water outlet, respectively.

[0017] Preferably, the probe of the ultrasonic vibration device abuts against the bottom surface of the worktable.

[0018] A method for suppressing smoke and dust during laser deposition repair of magnesium alloy parts includes the following steps: S1. Clean and regularize the defective parts of the components; S2. Place the parts into the box, pressurize the box through the pressurized air intake device, and remove dust through the exhaust gas treatment device; S3. Turn on the ultrasonic vibration device to homogenize the temperature field of the molten pool; S4. Laser deposition repair is performed in layers; S5. After repairing one layer, the part is forced to cool using the water cooling device; S6. After cooling is complete, repeat steps S4-S5 until all layer repairs are completed.

[0019] The present invention discloses the following technical effects: This invention uses a pressurized air intake device to fill the chamber with protective gas. During laser deposition repair, an ultrasonic vibration device provides disturbance to the molten pool, and a water cooling device forcibly cools the parts after each repair layer. Simultaneously, the chamber is dust-removed throughout the laser deposition repair process using an exhaust gas treatment device. This invention can not only effectively suppress the generation of smoke and dust during the laser repair of magnesium alloys, but also effectively reduce the generation of forming defects and improve mechanical properties. Attached Figure Description

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 This is a schematic diagram of the internal and external structure of the housing of the present invention; Figure 2 This is an overall flowchart of the present invention; The components include: 1. Housing; 2. Water cooling device; 3. Pressurized air intake device; 4. Exhaust gas treatment device; 11. Infrared temperature sensor; 12. Workbench; 13. Probe; 14. Ultrasonic vibration device; 21. Water inlet; 22. Water outlet; 31. First air inlet pipe; 32. Second air inlet pipe; 41. First air outlet pipe; 42. Second air outlet pipe. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] Reference Figures 1-2 This invention provides a device for suppressing dust from laser deposition repair of magnesium alloy parts, comprising a housing 1, a worktable 12 for placing parts is provided at the bottom of the housing 1, a water cooling device 2 for cooling the parts is provided on the top surface of the worktable 12, an ultrasonic vibration device 14 for providing disturbance to the molten pool is provided below the worktable 12, and an infrared temperature sensor 11 for monitoring the temperature of the parts is provided at the top of the housing 1; a pressurized air intake device 3 for supplying air into the housing 1 and a waste gas treatment device 4 for removing dust from the housing 1 are respectively connected to both sides of the housing 1.

[0025] The function of housing 1 is twofold: first, to seal the protective gas that has been filled in, and second, to bear the pressure.

[0026] The water-cooling device 2 typically includes a water cooling head (cooling module or cooling pipe), a coolant circulation system, a heat exchanger (radiator), and a temperature control system. The coolant is pressurized by a water pump from the water tank and flows through the water cooling head to absorb heat. The heated coolant enters the heat exchanger and dissipates heat through a fan or external cooling water. The temperature control system dynamically adjusts the flow rate and heat dissipation intensity to ensure a stable outlet temperature. The coolant returns to the water tank, forming a closed-loop circulation.

[0027] The pressurized gas intake device 3 typically includes a high-pressure gas storage tank (for storing inert gases such as argon), a gas pump (for providing gas pressure), a gas valve (for regulating flow rate), and a gas conduit (for transporting gas).

[0028] The exhaust gas treatment device 4 typically includes a gas pump (providing negative pressure suction), a gas valve (regulating flow rate), and a gas duct (transport path).

[0029] The infrared temperature sensor 11 is a non-contact temperature measurement device based on the blackbody radiation law. It calculates the temperature of an object by detecting the infrared radiation energy emitted from the surface of the object. It is widely used in industrial, medical, and security fields. In industrial applications, the infrared temperature sensor 11 is used for monitoring high-temperature equipment and pipelines. Some models of the infrared temperature sensor 11 can measure objects up to 3000℃.

[0030] The ultrasonic vibration device 14 is a technical device that utilizes the principle of ultrasonic vibration to achieve precision machining, material processing, and energy transfer. Its core function is to convert electrical energy into high-frequency mechanical vibration through the piezoelectric effect or magnetostrictive effect, and it is widely used in industry, medicine, scientific research, and other fields.

[0031] The ultrasonic vibration device 14 typically includes an ultrasonic generator (power supply), a vibration system, and auxiliary systems.

[0032] This invention uses a pressurized air intake device 3 to fill the housing 1 with protective gas. During laser deposition repair, an ultrasonic vibration device 14 provides disturbance to the molten pool. After each repair layer, the parts are forcibly cooled by a water cooling device 2. At the same time, during the laser deposition repair process, the housing 1 is dusted by an exhaust gas treatment device 4. This invention can not only effectively suppress the generation of smoke and dust during the laser repair of magnesium alloys, but also effectively reduce the generation of forming defects and improve mechanical properties.

[0033] The design is further optimized by providing air inlets on the upper and lower parts of the housing 1 facing the pressurized air intake device 3, respectively. These air inlets are connected to the air supply end of the pressurized air intake device 3. This allows the pressurized air intake device 3 to supply air from the upper and lower parts of the housing 1 separately, or to supply air from both the upper and lower parts simultaneously.

[0034] In a further optimized design, air outlets are provided on the upper and lower parts of the side of the housing 1 facing the exhaust gas treatment device 4, and these outlets are connected to the air inlet of the exhaust gas treatment device 4. This allows the exhaust gas treatment device 4 to draw in air from the upper and lower parts of the housing 1 separately, or to draw in air from both the upper and lower parts simultaneously.

[0035] The design has been further optimized by installing one-way control valves inside both the air inlet and outlet. These one-way control valves effectively control the opening and closing of each air inlet and outlet.

[0036] Further optimizing the design, the pressurized air intake device 3 is fixedly connected to a first air intake pipe 31 and a second air intake pipe 32. The first air intake pipe 31 is connected to the upper air intake port, and the second air intake pipe 32 is connected to the lower air intake port. The pressurized air intake device 3 supplies air to the housing 1 through the first air intake pipe 31 and the second air intake pipe 32.

[0037] In a further optimized design, the exhaust gas treatment device 4 is fixedly connected to a first exhaust pipe 41 and a second exhaust pipe 42. The first exhaust pipe 41 is connected to the upper exhaust port, and the second exhaust pipe 42 is connected to the lower exhaust port. The exhaust gas treatment device 4 cleans the smoke and dust inside the housing 1 through the first exhaust pipe 41 and the second exhaust pipe 42.

[0038] The design was further optimized so that water inlet 21 and water outlet 22 are respectively set on both sides of the workbench 12, and the water inlet 21 and water outlet 22 are opened on the box body 1.

[0039] Further optimizing the design, the water-cooling device 2 includes a cooling pipe embedded in the top surface of the workbench 12, with an inlet 21 and an outlet 22 extending out of the housing 1 at both ends. By embedding the cooling pipe in the top surface of the workbench 12, the water-cooling device 2 can effectively provide forced cooling to the parts on the workbench 12.

[0040] In a further optimized design, the probe 13 of the ultrasonic vibration device 14 abuts against the bottom surface of the worktable 12. This allows the ultrasonic vibration device 14 to effectively provide disturbance to the molten pool.

[0041] Throughout the laser deposition repair process, the pressure inside chamber 1 must be maintained at more than 3 atmospheres and controlled within 5 atmospheres.

[0042] In laser deposition restoration technology, argon is commonly used as a protective gas. By pressurizing the gas, when the ambient pressure reaches 3 atmospheres, the molten pool does not undergo violent evaporation during the restoration process due to the influence of pressure on the boiling point of magnesium, thus improving the smoke and dust problem. However, under high pressure (5 atmospheres), the temperature of the molten pool and laser plume increases significantly, leading to increased metal vapor splashing and ionization. In addition to argon, helium is also suitable as a protective gas for laser deposition restoration. For helium, the formation of splashes and plasma does not increase with the pressure observed above atmospheric pressure. Higher ambient pressure can be used to increase the boiling point of magnesium alloys. Considering economic conditions, a 50% argon and 50% helium mixture as a protective gas has essentially the same effect as helium. Therefore, under normal circumstances, pressurization can be used to suppress smoke and dust generation when using any of the three protective gases. When using argon, the pressure inside chamber 1 should be controlled at around 3 atmospheres. When using helium or a 50% argon and 50% helium mixture, the pressure can be appropriately increased for better suppression, but generally should not exceed 5 atmospheres.

[0043] The pressurized air intake device 3 is connected to a liquid gas cylinder, which provides pressure through high-pressure gas generated by the vaporization of liquid argon or helium. Helium has a lower density than air. When using helium as the base protective gas, open the one-way valve in the upper air intake and close the one-way valve in the lower air intake, simultaneously opening the one-way valve in the lower air intake to expel air from the chamber. A mixture of 50% argon and 50% helium has a lower density than air, and is introduced using the same method as helium. If argon has a higher density than air, the method is reversed.

[0044] The protective gas is a mixture, with argon, helium or a mixture of 50% argon and 50% helium as the base protective gas, and 0.2% (mass fraction) of sulfur tetrafluoride or 5% (mass fraction) of tetrafluoromethane added.

[0045] Sulfur hexafluoride (SF6) is commonly used in industry to protect molten magnesium alloys. Adding 0.2% (mass fraction) of SF6 can effectively inhibit the evaporation of magnesium alloys. SF6 reacts with molten magnesium to form a thin and dense protective film on the liquid surface, improving the stability and adhesion of the magnesium alloy. SF6 is recognized as a greenhouse gas, but it can be used stably in the closed environment of chamber 1 when used with exhaust gas treatment device 4. Meanwhile, tetrafluoromethane, which can replace SF6, can also be used to suppress the generation of magnesium alloy dust.

[0046] Considering the greenhouse effect of sulfur hexafluoride, the basic protective gas should be purged from the air and the chamber 1 should be completely sealed before filling the chamber 1. At the same time, monitoring should be strengthened and proper handling should be carried out after use. The exhaust gas treatment device 4 can effectively treat the gas and ensure that harmful gases do not flow into the atmosphere.

[0047] The ventilation ultrasonic vibration device 14 disturbs the molten pool for two reasons: first, to uniformize the temperature field within the molten pool, reduce peak temperature, and decrease smoke and dust; and second, to facilitate gas overflow and reduce porosity.

[0048] Laser deposition repair of magnesium alloys uses a Gaussian laser source, resulting in a difference in energy density between the center and edge regions of the molten pool. The central region has a higher actual temperature, making it more susceptible to elemental ablation. This invention uses an ultrasonic vibration device 14 to disturb the molten pool, thereby balancing the temperature field within it. The ultrasonic vibration device 14, positioned below the worktable 12, provides disturbance to the molten pool during deposition repair, creating an ultrasonic vibration field to assist processing and equalize the temperature field. This effectively suppresses excessively high temperatures in the central region of the molten pool, preventing the generation of smoke and dust. Simultaneously, it increases the gas overflow rate within the molten pool, reduces void defects, and improves the microstructure and mechanical properties. This invention can utilize the ultrasonic vibration device 14 to provide molten pool disturbance, but other vibration methods, including but not limited to mechanical vibration, can also be used.

[0049] Forced cooling of parts: The continuous deposition process of laser deposition repair generates a large amount of heat accumulation, which raises the temperature of the parts and causes the temperature of the subsequent deposition molten pool to rise, generating smoke and dust; the present invention uses a water cooling device 2 to force cooling of the parts after each layer of printing is completed.

[0050] According to relevant experimental results, when the surface temperature of the part is around 100℃, the deposited layer has a good bonding effect and does not generate thermal stress accumulation. This invention embeds a cold water pipe into the surface of the workbench 12 and uses a water-cooling device 2 to forcibly cool the parts and suppress dust generation; other cooling methods, including but not limited to air cooling, can also be used.

[0051] A method for suppressing smoke and dust during laser deposition repair of magnesium alloy parts includes the following steps: S1. Clean and regularize the defective parts of the parts; Before repairing the parts, the damaged parts of the parts need to be cleaned and regularized according to the regularization method, with the principle of minimizing damage to the parts, so as to facilitate the modeling of the repair area.

[0052] At the same time, the parts and the magnesium alloy powder prepared in advance for repair should be placed in a drying oven and dried at a temperature of 100-120℃ for more than 2 hours to ensure that the moisture in the repair area of ​​the parts and the powder is removed, and to avoid the generation of hydrogen pores, so as not to affect the forming structure and performance.

[0053] S2. After drying, allow the parts to cool naturally to room temperature. Place the parts into chamber 1, pressurize chamber 1 using pressurized air intake device 3, and simultaneously remove dust using exhaust gas treatment device 4. The supplied gas is a mixture (helium:sulfur hexafluoride, ranging from 99.5-99.8% to 0.2-0.5%) (pressure 3.0-5.0 atmospheres). The pressurized air intake device 3 pressurizes the protective atmosphere within chamber 1 to a pressure greater than 1 atmosphere, suppressing metal vapor. The protective gas is a mixture of inert gas and dust-suppressing gas.

[0054] The powder is added into the powder cylinder; the door of the box 1 is closed, and the basic protective gas is introduced. Since the basic protective gas mentioned in this invention is of three types with different densities, the box 1 has two air inlets and two air outlets. The two air inlets (outlets) are used separately and are controlled by a one-way control valve.

[0055] Taking helium as the basic protective gas as an example, the pressurization and inlet device is activated to connect the upper inlet, and the exhaust gas treatment device 4 is activated to exhaust gas from the lower outlet. The gas is continuously pressurized for more than 10 minutes to ensure that the air in the box 1 is emptied. The outlet is then closed, and while pressurizing, a dust suppression gas (0.2-0.5% sulfur hexafluoride or 5% tetrafluoromethane by mass fraction) is introduced.

[0056] S3. Turn on the ultrasonic vibration device 14 to homogenize the temperature field of the molten pool; the ultrasonic frequency is 18kHz and the impact amplitude is 25μm.

[0057] When the air pressure reaches 3MPa, the air inlet is closed and the ultrasonic vibration device 14 is turned on. This invention uses ultrasonic vibration, with the ultrasonic frequency set to 18-25kHz and the impact amplitude to 10-35μm, to ensure that the temperature field of the molten pool can be balanced, and to avoid excessive vibration causing violent disturbance of the molten pool. Turbulence will aggravate porosity defects and affect the microstructure and properties.

[0058] By applying ultrasonic vibration during additive manufacturing or repair, the temperature field of the molten pool can be homogenized, making the originally uneven temperature field more uniform, reducing the temperature in high-temperature areas, and suppressing smoke and dust.

[0059] S4. Perform laser deposition repair in layers; once ready, model the groove shape according to the regularization process, slice the layers to generate a layer-by-layer printing program, and begin laser deposition repair. (The inlet temperature of the cold water pipe on the part is 0~8℃, and the outlet temperature is 60~80℃) and perform interlayer cooling (start working on the next layer when the temperature reaches 100℃), controlling the temperature.

[0060] S5. After repairing one layer, the part is forcibly cooled by the water cooling device 2. After each layer is printed, the part needs to be forcibly cooled. Excessive heat accumulation will cause thermal cracks and affect the microstructure properties. The present invention uses the water cooling device 2 for cooling. The surface of the workbench 12 is embedded with pure copper water cooling pipes to forcibly cool the part.

[0061] By using low-temperature inert gas to force-cool the surface of the part with each layer and each step during additive manufacturing or repair, the part can be cooled down quickly, thus suppressing smoke and dust.

[0062] The infrared temperature sensor 11 inside the housing 1 monitors the surface temperature of the parts. When the surface temperature of the parts is about 100°C, it can not only avoid heat accumulation but also obtain a better bonding layer.

[0063] S6. After cooling is complete, the infrared temperature sensor 11 monitors the surface temperature of the part and it drops to 100°C. Then, the next layer of repair processing can be carried out. Repeat steps S4-S6 until all layers of repair are completed.

[0064] In the above steps S2-S6, in order to suppress the generation of smoke and dust during the magnesium alloy repair process, but to ensure zero smoke and dust production, the exhaust gas treatment device 4 needs to be turned on for dust removal throughout the entire processing.

[0065] Repeat the printing and cooling process until the defective area is repaired. Then, shut off the pressurized air intake device 3, water cooling device 2, and ultrasonic vibration device 14. Clean up any residue inside the chamber 1 to prevent environmental damage. After cleaning, shut off the exhaust gas treatment device 4. The overall magnesium alloy repair process is now complete. Refer to the detailed flowchart for more information. Figure 2 .

[0066] This invention suppresses the generation of magnesium alloy dust by employing a complete process of pressurizing the chamber 1, filling with mixed protective gas, homogenizing the temperature field of the molten pool, and forced cooling during laser additive manufacturing and repair of magnesium alloy parts.

[0067] Comparison of traditional methods and the present invention for repairing magnesium alloys The experimental material was EV31A, used to repair a trapezoidal groove (2mm at the bottom, 4mm in depth, and 45° at the bevel angle).

[0068] By comparing the repair process, it is evident that the smoke and dust of the present invention are significantly reduced. After the experiment, by collecting and weighing the smoke and dust in the box 1 and the traditional protective chamber, the total amount of smoke and dust in the box 1 is less than 50% of that in the traditional repair environment, which proves the actual effect of the smoke and dust suppression device.

[0069] Metallographic images of the two repair results were prepared and analyzed using an optical microscope.

[0070] Compared with traditional repair methods, the repair results using the dust suppression device of this invention show that, in addition to improved porosity, the inclusion defects in the tissue are also improved to a certain extent, the second characteristic of the tissue is uniformly distributed, and no thermal cracks are observed.

[0071] The elemental composition and content of the micro-area were analyzed by energy dispersive spectroscopy. The elemental distribution of the specimen repaired by the device of this invention was uniform. Compared with the elemental content in the original powder, the proportion of magnesium was still slightly reduced. However, compared with the specimen repaired in the traditional repair environment, the elemental content ratio of the specimen repaired by the device of this invention was closer to that of the original magnesium alloy powder.

[0072] Comparing the average room temperature tensile properties of the repaired specimens, the specimens repaired using the device of this invention have higher tensile strength and better mechanical properties.

[0073] This invention increases the pressure inside the chamber 1, raising the evaporation temperature of the magnesium alloy and making it less prone to dust generation; the protective gas is a mixed gas, using a basic protective gas to achieve a low-oxygen production environment, while adding a gas to inhibit magnesium alloy evaporation, further suppressing dust; a disturbed uniform temperature field is added to the molten pool to further suppress dust, while increasing the gas overflow rate in the molten pool, reducing the generation of void defects, and improving the repair structure and mechanical properties; forced cooling of parts during the repair process controls the part temperature, avoids excessive heat accumulation, and further suppresses dust.

[0074] Suppressing smoke and dust reduces elemental ablation, minimizes compositional variations, and avoids compositional gradients. This results in a more uniform microstructure, with more consistent grain morphology and size in the formed parts, thus reducing performance differences caused by microstructure inhomogeneity. Uniform internal stress reduces the formation of brittle phases, thereby improving overall strength and toughness.

[0075] Suppressing fumes can significantly control porosity defects in formed parts, preventing the initiation of some fatigue cracks and extending part life. Reducing fumes can lower the temperature gradient and thermal stress in the molten pool, preventing hot cracks caused by localized overheating. It also improves the internal continuity of the microstructure, enhancing the tensile strength and yield strength of the parts.

[0076] This invention combines multiple methods—pressurizing the chamber 1, using a mixed protective gas, externally disturbing the molten pool, and forced cooling of the parts—to effectively suppress the generation of smoke and dust during the laser repair of magnesium alloys. This invention utilizes high-pressure gas generated from the vaporization of liquid gas to provide a high-pressure environment for the chamber 1 and to supply the basic protective gas. Considering the different densities of various protective gases, two air inlets are designed, one at the top and one at the bottom, with one-way control valves controlling their on / off states. Correspondingly, two air outlets are used to vent air from the chamber and control the oxygen content.

[0077] This invention uses a mixed gas as a protective gas, consisting of six protective gas schemes composed of three basic protective gases and two smoke suppressing gases. The appropriate scheme is selected based on the specific repair situation and requirements. Considering the greenhouse effect of sulfur hexafluoride, this invention is equipped with an exhaust gas treatment device 4 connected to the gas outlet, which is used to treat the gas in the chamber 1 after the experiment, ensuring that the gas will not leak into the atmosphere and pollute the environment.

[0078] The present invention uses external vibration to apply disturbance to the molten pool, including but not limited to using ultrasonic vibration device 14 and mechanical vibration device.

[0079] To avoid the various effects of heat accumulation on the repair process, this invention embeds water-cooling pipes in the surface of the workbench 12 to forcibly cool the parts through water cooling. An infrared temperature sensor 11 is installed inside the housing 1 to monitor the surface temperature of the parts. When the temperature reaches a specific threshold, the next layer of deposition repair work is then carried out.

[0080] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0081] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A device for suppressing dust from laser deposition repair of magnesium alloy parts, characterized in that: Includes a housing (1), the bottom of which is provided with a workbench (12) for placing parts, the top surface of which is provided with a water cooling device (2) for cooling parts, the bottom of which is provided with an ultrasonic vibration device (14) for providing disturbance to the molten pool, and the top of which is provided with an infrared temperature sensor (11) for monitoring the temperature of parts; The two sides of the box (1) are respectively connected to a pressurized air intake device (3) for supplying air into the box (1) and a waste gas treatment device (4) for removing dust from the box (1).

2. The device for suppressing dust from laser deposition repair of magnesium alloy parts according to claim 1, characterized in that: The box (1) has air inlets on its upper and lower parts facing the pressurized air intake device (3), and the air inlets are connected to the air delivery end of the pressurized air intake device (3).

3. The device for suppressing dust from laser deposition repair of magnesium alloy parts according to claim 2, characterized in that: The box (1) has an air outlet on the upper and lower parts facing the exhaust gas treatment device (4), and the air outlet is connected to the air inlet of the exhaust gas treatment device (4).

4. The apparatus for suppressing dust from laser deposition repair of magnesium alloy parts according to claim 3, characterized in that: One-way control valves are installed in the air inlet and the air outlet respectively.

5. The device for suppressing dust from laser deposition repair of magnesium alloy parts according to claim 2, characterized in that: The pressurized air intake device (3) is fixedly connected with a first air intake pipe (31) and a second air intake pipe (32). The first air intake pipe (31) is connected to the upper air intake port, and the second air intake pipe (32) is connected to the lower air intake port.

6. The apparatus for suppressing dust from laser deposition repair of magnesium alloy parts according to claim 3, characterized in that: The waste gas treatment device (4) is fixedly connected with a first exhaust pipe (41) and a second exhaust pipe (42). The first exhaust pipe (41) is connected to the upper exhaust port, and the second exhaust pipe (42) is connected to the lower exhaust port.

7. The apparatus for suppressing dust from laser deposition repair of magnesium alloy parts according to claim 1, characterized in that: The workbench (12) is provided with an inlet (21) and an outlet (22) on both sides, and the inlet (21) and the outlet (22) are located on the box (1).

8. The apparatus for suppressing dust from laser deposition repair of magnesium alloy parts according to claim 7, characterized in that: The water cooling device (2) includes a cooling pipe embedded in the top surface of the workbench (12), with both ends of the cooling pipe extending out of the box body (1) through the water inlet (21) and the water outlet (22) respectively.

9. The apparatus for suppressing dust from laser deposition repair of magnesium alloy parts according to claim 1, characterized in that: The probe (13) of the ultrasonic vibration device (14) abuts against the bottom surface of the worktable (12).

10. A method for suppressing dust from laser deposition repair of magnesium alloy parts, based on the apparatus for suppressing dust from laser deposition repair of magnesium alloy parts according to any one of claims 1-9, characterized in that: Includes the following steps: S1. Clean and regularize the defective parts of the components; S2. Place the parts into the housing (1), pressurize the housing (1) through the pressurized air intake device (3), and remove dust through the exhaust gas treatment device (4); S3. Turn on the ultrasonic vibration device (14) to homogenize the temperature field of the molten pool; S4. Laser deposition repair is performed in layers; S5. After repairing one layer, the parts are forcibly cooled by the water cooling device (2); S6. After cooling is complete, repeat steps S4-S5 until all layer repairs are completed.

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