A reinforced protective nozzle specifically designed for laser deposition repair of magnesium and aluminum alloys.

Abstract

This invention belongs to the technical field of welding repair of magnesium and aluminum alloy cast blanks and machined parts for aerospace applications, and discloses a special reinforced protective nozzle for laser deposition repair of magnesium and aluminum alloys. The nozzle, from the inside out, comprises: an inner ring nozzle, a middle powder feeding nozzle, and an outer ring reinforced protective atmosphere nozzle; the inner ring nozzle is an inverted frustum with a coaxial laser through-hole in the center for the laser beam to pass through; the middle powder feeding nozzle is a conical annular frustum fitted outside the inner ring nozzle; the middle powder feeding nozzle has a powder flow channel running from top to bottom; the outer ring reinforced protective atmosphere nozzle is a conical annular frustum fitted outside the middle powder feeding nozzle; the upper end face of the outer ring reinforced protective atmosphere nozzle has an airflow inlet, the inner wall of the outer ring reinforced protective atmosphere nozzle and the outer wall of the middle powder feeding nozzle form an airflow channel, and a gap is provided between the inner wall of the lower end face of the outer ring reinforced protective atmosphere nozzle and the outer wall of the lower end face of the middle powder feeding nozzle to form an annular airflow outlet.

Description

Technical Field

[0001] This invention belongs to the field of welding repair technology for magnesium and aluminum alloy cast blanks and machined parts for aerospace applications, and specifically relates to a reinforced protective nozzle for laser deposition repair of magnesium and aluminum alloys. Background Technology

[0002] Magnesium and aluminum alloys, with their high specific strength and low density, are widely used in the manufacture of aerospace components. Cast magnesium and aluminum alloy parts often have complex shapes, including oil passages and thin-walled areas, making casting difficult. Furthermore, the low melting point and rapid heat dissipation of magnesium and aluminum alloys make the castings prone to defects such as porosity, segregation, and inclusions on the surface and inside. Additionally, parts may suffer minor damage such as impacts during processing and use. Repairing these parts by welding before they are finished can restore them to usability and mitigate economic losses.

[0003] Laser deposition repair technology is a surface modification and repair technique characterized by low heat input, good directivity, and high precision, and it has broad application prospects in the repair of magnesium and aluminum alloy castings. Currently, laser deposition repair technology has been used for the repair of some iron-based, titanium-based, and aluminum-based materials. However, magnesium alloys are prone to oxidation, and both the molten pool and the powder are susceptible to severe oxidation during the deposition process, affecting the repair quality and effect.

[0004] The coaxial powder feeding nozzle patents retrieved so far, while mostly ensuring stable powder feeding, smooth powder flow, and convergence, lack specialized nozzles for laser deposition of aluminum and magnesium alloys. During laser deposition, the nozzle is prone to overheating due to the high reflectivity of aluminum and magnesium alloys, leading to excessively high nozzle temperatures. Furthermore, the protective gas atmosphere of conventional nozzles cannot fully protect the molten pool and powder of aluminum and magnesium alloys, thus affecting the quality and deposition effect of the deposited layer.

[0005] The existing nozzle design has a narrow cooling channel that is only at the bottom of the nozzle. Although some patents have improved the nozzle structure, the flow of cooling water in the nozzle is uneven. After entering, the cooling water first flows through the axisymmetric half of the nozzle and then through the other half, which can easily lead to inconsistent cooling effects on both sides of the nozzle. Summary of the Invention

[0006] Objective: To address the insufficient protection and cooling effects during laser deposition repair of magnesium and aluminum alloy castings and machined parts, this invention proposes a specialized enhanced protective nozzle for magnesium and aluminum alloy laser deposition repair. This improves the protection effect during the laser deposition process of aluminum and magnesium alloys. To enhance protection, an outer ring protective gas structure is designed based on the traditional powder feeding nozzle structure, strengthening the protection of the molten pool and powder. Specifically, three protective gas streams—coaxial protective gas, powder carrier gas, and outer ring protective gas—protect the molten pool and powder. To improve cooling, an annular flow channel is incorporated into the inner nozzle, allowing water to flow sequentially from the bottom to the upper outlet, thus enhancing the cooling effect.

[0007] The technical solution of this invention is:

[0008] A special reinforced protective nozzle for laser deposition repair of aluminum-magnesium alloys, the nozzle comprising, from the inside out: an inner ring nozzle, a middle powder feeding nozzle, and an outer ring reinforced protective atmosphere nozzle;

[0009] The inner ring nozzle is an inverted frustum with a coaxial laser through hole in the middle for the laser beam to pass through;

[0010] The intermediate powder feeding nozzle is a conical ring platform sleeved on the outside of the inner ring nozzle; the intermediate powder feeding nozzle has a powder flow channel from top to bottom.

[0011] The outer ring reinforced protective atmosphere nozzle is a conical ring platform sleeved on the outside of the middle powder feeding nozzle; the upper end face of the outer ring reinforced protective atmosphere nozzle is provided with an airflow inlet, the inner wall of the outer ring reinforced protective atmosphere nozzle and the outer wall of the middle powder feeding nozzle form an airflow channel, and the inner wall of the lower end face of the outer ring reinforced protective atmosphere nozzle and the outer wall of the lower end face of the middle powder feeding nozzle are provided with a gap to form an annular airflow outlet.

[0012] Furthermore, the outer wall of the inner ring nozzle is provided with a cooling water tank; the upper end face of the inner ring nozzle is provided with a water inlet and a water outlet, which are respectively connected to the two ends of the cooling water tank; the outer wall of the inner ring nozzle and the inner wall of the intermediate powder delivery nozzle are closely fitted to form a complete cooling water flow channel.

[0013] Furthermore, the cooling water tank includes a vertical water tank and a spiral water tank; after the cooling water enters the cooling water tank from the inlet, it extends from top to bottom along the vertical water tank to the bottom of the inner ring nozzle, and then spirals up along the spiral water tank to the top outlet of the inner ring nozzle.

[0014] Furthermore, the cooling water tank includes a vertical water tank and N layers of horizontal annular water tanks;

[0015] After entering the cooling water tank from the inlet, the cooling water extends from top to bottom along the vertical water tank to the bottom of the inner ring nozzle. In the first ring water tank, it flows counterclockwise horizontally to the left side of the vertical water tank and then rises to the second ring water tank.

[0016] In the second annular water tank, it flows clockwise to the right side of the vertical water tank and then rises to the third annular water tank.

[0017] The flow pattern in the first and second annular water tanks is repeated in the horizontal channels from the third to the Nth layer until the water flows to the outlet.

[0018] Furthermore, the outer ring reinforces the outer wall of the nozzle, the inner and outer walls of the intermediate powder feeding nozzle, and the outer wall of the inner ring nozzle all have the same taper.

[0019] Furthermore, the powder flow channel is provided with three bundles, evenly distributed circumferentially, and the three powder flow channels have the same taper. The convergence point of the axes of the three powder flow channels is located on the central axis of the inner ring nozzle.

[0020] Furthermore, the outer ring reinforces the protective atmosphere nozzle inner wall with three layers of asbestos mesh and two layers of air distribution plates between the middle powder feeding nozzle outer wall, and the two layers of air distribution plates are located between the three layers of asbestos mesh.

[0021] Furthermore, the number of air distribution holes in the lower air distribution plate is twice the number of air distribution holes in the upper air distribution plate.

[0022] Furthermore, the outer ring reinforced protective atmosphere nozzle has four airflow inlets evenly distributed circumferentially on its upper surface.

[0023] This invention offers the following advantages: It proposes a specialized enhanced protective nozzle for laser deposition repair of magnesium and aluminum alloys. Based on the traditional powder feeding nozzle structure, an outer ring protective gas structure is designed to strengthen the protection of the molten pool and powder. Specifically, a three-channel protective gas system—coaxial protective gas, powder carrier gas, and outer ring protective gas—protects the molten pool and powder. To improve cooling, an annular flow channel is incorporated into the inner nozzle, allowing water to flow sequentially from the bottom to the upper outlet, further enhancing the cooling effect. Attached Figure Description

[0024] Figure 1 A top view of a reinforced protective nozzle specifically designed for laser deposition repair of aluminum-magnesium alloys;

[0025] Figure 2 This is a schematic diagram of the inner ring nozzle structure;

[0026] Figure 3 A schematic diagram of the combined structure of the intermediate powder feeding nozzle and the outer ring reinforced protective atmosphere nozzle;

[0027] Figure 4 This is a schematic diagram of a gas distribution plate;

[0028] 1-Inner ring nozzle, 2-Intermediate powder delivery nozzle, 3-Outer ring reinforced protective atmosphere nozzle, 4-Water inlet, 5-Water outlet, 6-Powder delivery pipeline, 7-Air inlet, 8-Annular water tank or spiral water tank, 9-Water tank wall, 10-Cooling water direct flow channel, 11-Asbestos mesh, 12-A-Gas distribution plate, 13-B-Gas distribution plate, 14-A-Ventilation hole, 15-B-Ventilation hole. Detailed Implementation

[0029] This section describes embodiments of the present invention, used to explain and illustrate the technical solutions of the present invention.

[0030] A special reinforced protective nozzle for laser deposition repair of magnesium and aluminum alloys is mainly composed of three functional modules: an inner ring nozzle 1, a middle powder feeding nozzle 2, and an outer ring reinforced protective atmosphere nozzle 3.

[0031] The inner ring nozzle is an inverted frustum with a coaxial laser through-hole in the center for the laser beam to pass through. The outer wall of the inner ring nozzle has a cooling water channel, a water-cooled stepped flow channel, along which cooling water flows to cool the nozzle. There are two types of cooling water channels.

[0032] Implementation method 1: The cooling water flow channel includes a vertical water channel and a spiral water channel; after the cooling water enters the cooling water flow channel from the inlet, it extends from top to bottom along the vertical water channel to the bottom of the inner ring nozzle, and then spirals up along the spiral water channel to the top outlet of the inner ring nozzle.

[0033] Implementation method 2: The cooling water flow channel includes a vertical water tank and N layers of horizontal annular water tanks;

[0034] After entering the cooling water channel from the inlet, the cooling water extends from top to bottom along the vertical water tank to the bottom of the inner ring nozzle. In the first ring water tank, it flows counterclockwise horizontally to the left side of the vertical water tank and then rises to the second ring water tank.

[0035] In the second annular water tank, it flows clockwise to the right side of the vertical water tank and then rises to the third annular water tank.

[0036] The flow pattern in the first and second annular water tanks is repeated in the horizontal channels from the third to the Nth layer until the water flows to the outlet.

[0037] In its specific operation, cooling water flows in from inlet 4, through the cooling water direct current channel 10, and to the bottom of the cooling water channel, entering the lowest layer (first layer). After circulating once, the cooling water enters the second layer through the interlayer opening next to the direct current channel. After circulating once in the second layer, it enters the third layer through the interlayer opening. After circulating once in the third layer, it enters the fourth layer through the interlayer opening. After circulating once in the fourth layer, it enters the fifth layer through the interlayer opening. After circulating once in the fifth layer, it flows out of the cooling channel from cooling water outlet 5. The entire cooling water flows within the cooling tank, circulating and cooling the nozzles. Both the cooling water inlet and outlet are located on the upper surface of the nozzles, facilitating installation and saving space. This design allows the cooling water to flow upwards layer by layer after entering the cooling steps, achieving thorough cooling.

[0038] The intermediate powder feeding nozzle is a conical ring platform sleeved on the outside of the inner ring nozzle; the intermediate powder feeding nozzle has a powder flow channel from top to bottom.

[0039] The inner wall of the intermediate powder feeding nozzle fits into the outer wall of the inner ring nozzle, forming a complete cooling water flow channel, allowing cooling water to flow within it. The intermediate powder feeding nozzle has three powder feeding pipes, machined into the nozzle. These pipes are distributed at 120° intervals, with the axis of each pipe aligned with the axis of the intermediate cavity on the same plane, and the angle between each pipe axis and the intermediate cavity axis being the same. During powder feeding, powder enters through the inlet on the upper surface of the intermediate powder feeding nozzle and exits through the outlet at the lower surface, ultimately converging at the same position below the nozzle.

[0040] The outer ring reinforced protective atmosphere nozzle is a conical annular platform fitted outside the intermediate powder feeding nozzle. The upper surface of the outer ring reinforced protective atmosphere nozzle has an airflow inlet. An airflow channel is formed between the inner wall of the outer ring reinforced protective atmosphere nozzle and the outer wall of the intermediate powder feeding nozzle. A gap is formed between the inner wall of the lower surface of the outer ring reinforced protective atmosphere nozzle and the outer wall of the lower surface of the intermediate powder feeding nozzle, forming an annular airflow outlet. The upper surface of the outer ring reinforced protective atmosphere nozzle has four air inlets 7, designed to be symmetrically distributed at a 90° angle, which facilitates uniform gas flow into the protective gas chamber. The conical slope design from the air inlets to the annular airflow outlet increases the convergence and initial velocity of the protective gas exiting the annular outlet, thus enhancing the protective atmosphere.

[0041] Three layers of asbestos mesh and two layers of gas distribution plates are provided between the inner wall of the outer ring reinforced protective atmosphere nozzle and the outer wall of the intermediate powder delivery nozzle, with the two layers of gas distribution plates located between the three layers of asbestos mesh. The asbestos mesh and gas distribution holes facilitate uniform gas distribution, allowing the gas to flow out evenly from the outlet ring, thus preventing turbulence when the gas flows through the cavity.

[0042] During operation, the laser passes through the central cavity, and the radiation from the laser heats the nozzle, which is then cooled by the inner ring nozzle. Cooling water enters through inlet 4 and flows out through outlet 5, circulating to cool the nozzle. Powder enters through powder feeding pipes 6, which consist of three pipes distributed at 120° intervals, eventually converging below the nozzle at a point intersecting the laser axis and the central cavity axis. The outermost ring nozzle, reinforced with a protective atmosphere, protects the molten pool formed by laser deposition.

[0043] The protective gas enters through four air inlets 7 on the upper surface of the outer ring reinforced protective atmosphere nozzle. These four inlets are evenly distributed at 90° intervals. After entering the cavity, the protective gas is diverted by the first layer of asbestos mesh 11. The asbestos mesh 11 serves to homogenize the protective gas flow and prevent excessive concentration of airflow after exiting the cavity. After homogenization by the first layer of asbestos mesh, the protective gas passes through the first layer of A-type gas distribution plate 12. The A-type gas distribution plate 12 has 12 evenly distributed A-type vents 14 at 30° intervals, further homogenizing the protective gas entering from the first layer of asbestos. After passing through the first layer of A-type gas distribution plate 12, the protective gas enters the second layer of asbestos, further homogenizing the protective gas flow. The protective gas then reaches the second layer, the B-type gas distribution plate 13. This plate has 24 B-type vent holes 15 spaced at 15° intervals. Furthermore, the vent holes on the B-type and A-type gas distribution plates 13 are staggered, further homogenizing the protective gas. After passing through the B-type plate 13, the protective gas enters the final layer of asbestos mesh and finally flows out of the reinforced protective atmosphere nozzle through the annular structure below it. The outflowing protective gas forms a cone shape downwards, maximizing the protection of the molten pool.

Claims

1. A reinforced protective nozzle specifically designed for laser deposition repair of aluminum-magnesium alloys, characterized in that: The nozzle, from the inside out, includes: an inner ring nozzle, a middle powder feeding nozzle, and an outer ring reinforced protective atmosphere nozzle; The inner ring nozzle is an inverted frustum with a coaxial laser through hole in the middle for the laser beam to pass through; The intermediate powder feeding nozzle is a conical ring platform sleeved on the outside of the inner ring nozzle; the intermediate powder feeding nozzle has a powder flow channel from top to bottom. The outer ring reinforced protective atmosphere nozzle is a conical ring platform sleeved on the outside of the middle powder feeding nozzle; the upper end face of the outer ring reinforced protective atmosphere nozzle has four airflow inlets evenly distributed circumferentially; the inner wall of the outer ring reinforced protective atmosphere nozzle and the outer wall of the middle powder feeding nozzle form an airflow channel; and a gap is provided between the inner wall of the lower end face of the outer ring reinforced protective atmosphere nozzle and the outer wall of the lower end face of the middle powder feeding nozzle to form an annular airflow outlet. The outer wall of the inner ring nozzle is provided with a cooling water tank; the upper end face of the inner ring nozzle is provided with an inlet and an outlet, which are respectively connected to the two ends of the cooling water tank; the outer wall of the inner ring nozzle and the inner wall of the intermediate powder delivery nozzle are closely fitted to form a complete cooling water flow channel; the cooling water tank includes a vertical water tank and a spiral water tank; after the cooling water enters the cooling water tank from the inlet, it extends from top to bottom along the vertical water tank to the bottom of the inner ring nozzle, and then spirals up along the spiral water tank to the top outlet of the inner ring nozzle; Three layers of asbestos mesh and two layers of air distribution plates are provided between the inner wall of the outer ring reinforced protective atmosphere nozzle and the outer wall of the intermediate powder feeding nozzle, with the two layers of air distribution plates located between the three layers of asbestos mesh; 12 A vent holes are evenly distributed on the first layer of air distribution plate, with the 12 A vent holes being evenly distributed at 30°; 24 B vent holes are distributed on the second layer of air distribution plate, with the 24 B vent holes being distributed at 15° intervals; the air inlets on the two layers of air distribution plate are staggered.

2. The enhanced protective nozzle according to claim 1, characterized in that: The cooling water tank includes a vertical water tank and N layers of horizontal annular water tanks; After entering the cooling water tank from the inlet, the cooling water extends from top to bottom along the vertical water tank to the bottom of the inner ring nozzle. In the first ring water tank, it flows counterclockwise horizontally to the left side of the vertical water tank and then rises to the second ring water tank. In the second annular water tank, it flows clockwise to the right side of the vertical water tank and then rises to the third annular water tank. The flow pattern in the first and second annular water tanks is repeated in the horizontal channels from the third to the Nth layer until the water flows to the outlet.

3. The enhanced protective nozzle according to claim 2, characterized in that: The outer ring reinforces the outer wall of the nozzle, the inner and outer walls of the intermediate powder feeding nozzle, and the outer wall of the inner ring nozzle all have the same taper.

4. The enhanced protective nozzle according to claim 3, characterized in that: The powder flow channel is provided with three bundles, which are evenly distributed circumferentially. The three powder flow channels have the same taper, and the convergence point of the axes of the three powder flow channels is located on the central axis of the inner ring nozzle.

Images