Laminar airborne powder feeding high-speed deposition device, high-speed laser cladding deposition device and method

Abstract

The invention provides a laminar flow airborne powder feeding high-speed deposition device and a high-speed laser deposition device and method.The laminar flow airborne powder feeding high-speed deposition device comprises an output head body which is provided with a center powder feeding pipe, a center nozzle, a first sheath gas conveying channel and a second sheath gas conveying channel, and the center nozzle is arranged along the center axis of the output head body; the central powder feeding pipe and the central nozzle are communicated and coaxially arranged, the first sheath gas conveying channel and the second sheath gas conveying channel are both communicated with the peripheral side of the central nozzle, the central powder feeding pipe is used for being connected with a powder source, and the first sheath gas conveying channel and the second sheath gas conveying channel are used for being connected with a sheath gas source. The central nozzle is arranged to form a powder laminar flow in the central nozzle, and the powder laminar flow comprises a powder flow conveyed in the direction of the central axis and sheath gas surrounding the powder flow. According to the method, high-precision cladding machining and forming of irregular structures can be achieved, the product quality is optimized, and the forming efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology, and more specifically, to a laminar flow gas-carried powder high-speed deposition apparatus, a high-speed laser deposition apparatus, and a method. Background Technology

[0002] High-speed laser deposition technology uses lasers to deposit or coat high-performance metal materials on the surface of a component substrate. Unlike ordinary laser deposition processes, with a higher relative moving speed between the laser head and the sample, the powder melts at a certain distance from the workpiece and is sprayed at high speed onto the workpiece surface to form an extremely thin metallurgical layer. The light-powder convergence point is on the upper part of the workpiece rather than on the surface, which can achieve low dilution rate, low layer thickness (the minimum coating thickness can be as low as 100μm), and small deformation of the cladding coating, with almost no damage to the workpiece substrate. At the same time, it achieves high metallurgical quality and high surface finish, and can quickly prepare large-area coatings in a short time, while effectively extending the product service life.

[0003] Standard laser cladding speeds range from 0.5 to 2 m / min, while high-speed laser cladding speeds reach 5 to 200 m / min. Existing high-speed laser cladding processes are mainly aimed at coating preparation for shaft-like components. For the processing of three-dimensional curved parts, the high-speed movement speed of robotic arms or machine tools is limited, making it impossible to solve the problem of high-speed movement of traditional laser cladding heads on the surface of three-dimensional curved parts.

[0004] On the other hand, in applications where the heat source moves at high speed, such as high-speed cladding coatings for three-dimensional curved surfaces and high-speed 3D printing repair, the high-speed moving heat source and powder feeding system cannot be linked when using a high-speed laser galvanometer. Therefore, achieving stable and efficient powder delivery is a crucial issue. To adapt to the irregular surface undulations of the heat source processing area, it is necessary to increase the focal point range of the powder along the vertical direction. Currently, the powder feeding method for laser direct deposition technology generally uses a gas-carrying powder feeder. Its working principle is that a high-speed airflow draws in the powder through a designed nozzle and mixes it in the airflow, then precisely delivers it to the target area to achieve uniform powder spraying or filling. The nozzle shape used in this method is generally an inverted cone, designed to create a focal point for the powder, called a powder spot. In this process, the output metal powder often forms a ring distribution or a multi-path circumferential distribution around the laser, exhibiting different powder spot sizes at different processing heights. Specifically, processing heights deviating from the powder focus result in under-focusing of the powder spot (different heights cause inconsistent powder spot diameters), leading to problems such as low surface accuracy and poor forming quality due to powder spot instability. Therefore, increasing the focal point range of additive powder along the processing direction is key to addressing the problem of irregular surface undulations in the processing area of ​​the heat source. Simultaneously, in addition to increasing the focal point range along the processing direction, it is necessary to modify the turbulent powder state. Turbulent powder exiting the nozzle causes powder splashing, reducing powder utilization efficiency and interfering with the formation of powder spots. Summary of the Invention

[0005] (a) Technical problems to be solved The technical problem to be solved by this invention is the low surface accuracy and poor forming quality caused by unstable powder spots during the processing of three-dimensional curved parts.

[0006] (II) Technical Solution To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides a laminar flow gas-carried powder high-speed deposition apparatus, including an output head body, a central powder delivery pipe, a central nozzle, a first sheath gas delivery channel, and a second sheath gas delivery channel. The central nozzle is arranged along the central axis of the output head body. The central powder delivery pipe is connected to and coaxially arranged with the central nozzle. The first and second sheath gas delivery channels are both connected to the periphery of the central nozzle. The central powder delivery pipe is used to connect to a powder source, and the first and second sheath gas delivery channels are used to connect to a sheath gas source to form a powder laminar flow in the central nozzle. The powder laminar flow includes a powder flow transported along the central axis and sheath gas surrounding the powder flow.

[0007] Preferably, the cross-sectional shape of the central nozzle is circular, elliptical, or pea-pod shaped.

[0008] Preferably, it further includes a cooling head, which has a cooling channel for the flow of cooling medium, and the cooling head is threadedly connected to the output head body.

[0009] Preferably, the cooling head is annular, the cooling head has an internal thread, the cooling channel surrounds the internal thread, the output head body has an external thread, and the internal thread is threadedly connected to the external thread.

[0010] Preferably, the Reynolds number Re of the powder laminar flow is less than or equal to 2300, and the gas velocity of the sheath gas is equal to the velocity of the powder flow.

[0011] Secondly, the present invention also provides a high-speed laser cladding deposition apparatus for performing high-speed laser cladding deposition of powder on the surface of a three-dimensional curved part. The apparatus is characterized by comprising a driving component, a laser output component, and any one of the laminar flow gas-carrying powder high-speed deposition devices described above. The driving component is connected to the three-dimensional curved part and is used to drive the three-dimensional curved part to rotate along an axis. The laminar flow gas-carrying powder high-speed deposition device is used to deposit powder on the surface of the three-dimensional curved part to form powder spots. The laser output component is used to output laser light, which acts on the powder on the surface of the three-dimensional curved part.

[0012] Preferably, the laser output assembly includes a laser source, a dynamic focusing lens, a focusing lens, an X-axis rotating galvanometer, and a Y-axis rotating galvanometer. The laser source is used to output laser light. The dynamic focusing lens, the focusing lens, the X-axis rotating galvanometer, and the Y-axis rotating galvanometer are arranged sequentially along the optical path of the laser. The dynamic focusing lens is used to focus the laser light and can move along the optical path of the laser light. The focusing lens is used to focus the laser light. The X-axis rotating galvanometer is used to shift the position of the laser light in the X-axis direction, and the Y-axis rotating galvanometer is used to shift the position of the laser light in the Y-axis direction.

[0013] Preferably, on the surface of the three-dimensional curved part, the position of the powder spot is offset by 0-3mm from the center of the laser spot towards the direction of molten pool dragging.

[0014] Preferably, it also includes an inert gas protection box, in which the three-dimensional curved surface part, the driving assembly, the laser output assembly, and the laminar flow gas-carried powder high-speed deposition device are all disposed.

[0015] Thirdly, the present invention also provides a high-speed laser cladding deposition method, implemented using any of the high-speed laser cladding deposition apparatuses described above, comprising the following steps: After completing the part model planning, determine the area to be processed, fix the output head body directly above the three-dimensional curved surface part to be processed or at an angle of no more than 20°, set the laser output component and the output head body to be offset, and set the entire high-speed laser cladding deposition device in an inert gas protective box. The preset path for forming scanning uses the area to be processed as the scanning base surface, and the area to be clad is obtained by reverse engineering the digital model or the original digital model. Layered slicing is performed with a layer thickness of 20-100μm, and the scanning overlap rate is 60-90%. Adjust the position of the central nozzle to ensure that the position of the powder spot output by the central nozzle is offset by 0-3mm from the center of the laser spot in the direction of dragging the molten pool; Turn on the inert gas and wait until the oxygen content is below 1000 PPM. Then start the high-speed laser cladding deposition device and carry out high-speed laser cladding deposition based on the preset path. The overall direction of the laser moves along the axis of the three-dimensional curved part. During the process, the dynamic focusing lens is driven to move to achieve dynamic focusing along the Z direction, ensuring that the laser focus point is always on the surface of the rotating three-dimensional curved part.

[0016] (III) Beneficial Effects The above-described technical solution of the present invention has at least the following advantages: This patented solution effectively addresses the dynamic focusing issue during real-time machining of parts during high-speed rotation in applications such as high-speed cladding coating of three-dimensional curved surfaces and high-speed 3D printing repair. It also solves problems like low surface precision and poor forming quality caused by uneven powder spots due to irregular surface undulations. Ultimately, it achieves high-precision cladding processing and forming of irregular structures, optimizing product quality and improving forming efficiency.

[0017] This invention provides a laminar flow air-carrying powder high-speed deposition apparatus. Powder flows into the central powder delivery pipe via a front-end powder delivery device using air-carrying / ultrasonic vibration delivery. Simultaneously, sheath gas is introduced through a first and a second sheath gas delivery channel. The sheath gas surrounds the powder in a ring shape for stable flow. After uniform mixing, the powder merges into a single vertical channel and exits from the central nozzle. The central powder delivery pipe extends deep into the sheath gas stabilization zone, ensuring that the powder airflow is completely parallel upon contact with the sheath gas, ultimately outputting a stable powder flow protected by sheath gas. The central nozzle is surrounded by a threaded water-cooled pipeline to prevent overheating of the laser head. This apparatus ensures that the powder spot output from the central nozzle is in a stable circular shape, guaranteeing uniform powder spraying or filling over a large processing distance, achieving consistent powder spot size over a wider processing area, and increasing the focal point range of powder convergence. Furthermore, to prevent the powder output from the central nozzle from being blown away and to ensure its smooth arrival at the surface molten pool, the introduced sheath gas reduces the frictional resistance between the air-carrying powder and the inner wall of the flow channel, stabilizing the pipeline velocity gradient. By matching the sheath gas pressure, air-carrying input gas pressure, nozzle diameter, powder type and powder loading, the Reynolds number Re is controlled within 2300, and the sheath gas flow rate is the same as the powder feeding gas flow rate, ultimately outputting a stable powder laminar flow to adapt to the undulation of irregular surfaces during the forming process.

[0018] This invention provides a high-speed laser cladding deposition device. High-speed xy-axis scanning is achieved through X-axis and Y-axis rotating galvanometers combined with dynamic focusing in the z-axis by a dynamic focusing mirror, forming a high-speed moving light spot in three-dimensional space. The servo motor driving the galvanometers is driven by analog voltage. The dynamic focusing mirror performs reciprocating linear motion in the optical path direction to compensate for focusing errors, thereby ensuring real-time dynamic focusing for processing three-dimensional curved parts during high-speed rotation in the z-axis. The powder spot output from the central nozzle includes, but is not limited to, circular, elliptical, and pea-pod shaped particles. The powder spot output point is adjusted to 0-3mm in the direction of the molten pool drag to improve powder utilization, increase powder melting time, and enhance the powder melting effect. Simultaneously, the absence of sharp edges ensures stable laminar powder delivery, ultimately achieving high-precision cladding processing and forming of irregular structures, optimizing product quality, and improving forming efficiency. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is one of the structural schematic diagrams of the laminar flow gas-carried powder high-speed deposition device provided in the embodiments of the present invention.

[0021] Figure 2 This is the second schematic diagram of the laminar flow gas-carried powder high-speed deposition device provided in the embodiments of the present invention.

[0022] Figure 3 This is a cross-sectional view of the output head body provided in an embodiment of the present invention.

[0023] Figure 4 This is a schematic diagram showing the morphology and relative position of the powder spot output point and the laser spot before adjustment, provided in an embodiment of the present invention.

[0024] Figure 5 This is a schematic diagram showing the morphology and relative position of the powder spot output point and the laser spot after adjustment, provided in an embodiment of the present invention.

[0025] The labels for the attached figures are as follows: 10. Output head body; 11. Central powder delivery pipe; 12. Central nozzle; 13. First sheath gas delivery channel; 14. Second sheath gas delivery channel; 15. Cooling head; 16. Coolant interface; 17. Central input port cover; 20. Laser output assembly; 21. Laser source; 22. Dynamic focusing lens; 23. Focusing lens; 24. X-axis rotating galvanometer; 25. Y-axis rotating galvanometer; 30. Three-dimensional curved surface part; 151. Cooling channel. Detailed Implementation

[0026] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0027] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be located directly on or indirectly on the other component. When a component is referred to as "connected to" another component, it can be directly or indirectly connected to the other component.

[0028] It should be understood that the terms "length", "width", "up", "down", "front", "back", "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 the present invention, and do not indicate that the device or element must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating relative importance or the number of technical features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. The specific implementation of this invention will be described in more detail below with reference to specific embodiments: like Figure 1 , Figure 2 and Figure 3 As shown, this embodiment of the invention provides a laminar flow gas-carried powder high-speed deposition apparatus, including an output head body 10, with a central powder delivery pipe 11, a central nozzle 12, a first sheath gas delivery channel 13, and a second sheath gas delivery channel 14. The central nozzle 12 is arranged along the central axis of the output head body 10. The central powder delivery pipe 11 is connected to and coaxially arranged with the central nozzle 12. The first sheath gas delivery channel 13 and the second sheath gas delivery channel 14 are both connected to the periphery of the central nozzle 12. The central powder delivery pipe 11 is used to connect to a powder source, and the first sheath gas delivery channel 13 and the second sheath gas delivery channel 14 are used to connect to a sheath gas source to form a powder laminar flow in the central nozzle 12. The powder laminar flow includes a powder flow transported along the central axis and sheath gas surrounding the powder flow. Specifically, a center input port cover 17 is provided on one side of the output head body 10. The center input port cover 17 has multiple interfaces for connecting a powder source or a sheath gas source. The center input port cover 17 is fixed to the output head body 10 with eight Phillips head screws. A sealing ring should be provided between the center input port cover 17 and the output head body 10 to prevent gas leakage. The working principle is as follows: First, the powder flows into the center input port cover through the front-end powder feeding device via high-speed airflow / ultrasonic vibration. Then, the sheath gas is introduced from... Figure 3 The two interfaces above the center input port cover shown in the diagram connect to the output head body 10. Sheath gas surrounds the powder in a ring shape for stable flow. The shape of the center powder delivery pipe 11 is adjustable. Figure 5 The output powder flow is consistent with the sheath flow direction.

[0030] In this embodiment, to address the problem of insufficient focal depth in the powder feeding device of the high-speed galvanometer system, a laminar air-carrying powder high-speed deposition device is designed. The powder flows into the laminar air-carrying powder high-speed deposition device through the front-end powder feeding device in the form of high-speed air-carrying / ultrasonic vibration. At the same time, the sheath gas surrounds the powder in a ring shape to stabilize the flow. After being mixed evenly, the powder is combined into a vertical single channel (central nozzle 12). The central powder delivery pipe 11 needs to extend deep into the sheath gas stabilization zone (i.e., the outlet end of the central powder delivery pipe 11 needs to be longer than the outlet ends of the first sheath gas delivery channel 13 and the second sheath gas delivery channel 14) to ensure that the powder flow is completely parallel when it comes into contact with the sheath gas, and finally outputs a stable powder laminar flow protected by sheath gas. On the one hand, this device can ensure that the powder spot output from the central nozzle 12 is in a circular state with a stable diameter, and can ensure uniform spraying or filling of powder within a large processing distance, achieving a consistent powder spot size over a larger processing range and increasing the focal range of powder convergence. At the same time, in order to ensure that the powder output from the central nozzle 12 is not blown away and reaches the surface molten pool smoothly, the introduced sheath gas can reduce the frictional resistance between the air-carried powder and the inner wall of the flow channel of the central nozzle 12, and stabilize the pipeline velocity gradient.

[0031] In one embodiment, the cross-sectional shape of the central nozzle 12 is circular, elliptical, or pea-pod shaped.

[0032] In one embodiment, a cooling head 15 is also included, which has a cooling channel 151 for the flow of cooling medium. The cooling head 15 is threadedly connected to the output head body 10. The central nozzle 12 is water-cooled by the threaded cooling channel 151 to prevent the laser head from overheating. The cooling head 15 is threadedly connected to the output head body 10, and also threadedly connected to the coolant interface 16. All threaded connections should be equipped with sealing rings to prevent coolant leakage. The coolant is supplied by… Figure 3 The coolant is fed into the pipe via the coolant inlet 16 on the left side, and the coolant is output from the coolant inlet 16 on the right side through the rectangular groove engraved on the lower end of the output head body 10.

[0033] In one embodiment, the cooling head 15 is annular, has an internal thread, a cooling channel 151 surrounds the internal thread, and the output head body 10 has an external thread, with the internal thread and the external thread being threadedly connected.

[0034] In one embodiment, the Reynolds number Re of the powder laminar flow is less than or equal to 2300, and the gas velocity of the sheath gas is equal to the velocity of the powder flow. By matching the sheath gas pressure, the air-carrying input gas pressure, the nozzle diameter, the powder type, and the powder loading, the Reynolds number Re is controlled to be within 2300, and the sheath gas velocity must be the same as the powder delivery gas velocity, ultimately outputting a stable powder laminar flow to adapt to the undulations of irregular surfaces during the forming process.

[0035] This invention also provides a high-speed laser cladding deposition apparatus for high-speed laser powder cladding deposition on the surface of a three-dimensional curved part 30. The apparatus is characterized by comprising a drive component (not shown), a laser output component 20, and any of the laminar flow gas-carried powder high-speed deposition devices described above. The drive component is connected to the three-dimensional curved part 30 and drives the part to rotate along its axis. The laminar flow gas-carried powder high-speed deposition device is used to deposit powder on the surface of the three-dimensional curved part 30 to form powder spots. The laser output component 20 outputs laser light, which acts on the powder on the surface of the three-dimensional curved part 30. Specifically, the drive component can be a machine tool, with the three-dimensional curved part 30 fixedly mounted on the drive shaft of the machine tool for rotation; or the drive component can be a rotary motor, with the three-dimensional curved part 30 clamped and fixed on the output shaft of the rotary motor.

[0036] In one embodiment, the laser output assembly 20 includes a laser source 21, a dynamic focusing lens 22, a focusing lens 23, an X-axis rotating galvanometer 24, and a Y-axis rotating galvanometer 25. The laser source 21 is used to output laser light. The dynamic focusing lens 22, the focusing lens 23, the X-axis rotating galvanometer 24, and the Y-axis rotating galvanometer 25 are arranged sequentially along the optical path of the laser. The dynamic focusing lens 22 is used to focus the laser light and can move along the optical path of the laser light. The focusing lens 23 is used to focus the laser light. The X-axis rotating galvanometer 24 is used to shift the position of the laser light in the X direction, and the Y-axis rotating galvanometer 25 is used to shift the position of the laser light in the Y direction. In this embodiment, to address the problem that traditional cladding heads cannot move at high speed on a rapidly rotating asymmetric axis surface, a design is made that uses X-rotating galvanometer 24 and Y-rotating galvanometer 25 for high-speed X and Y-axis scanning in conjunction with a dynamic focusing mirror 22 for dynamic focusing in the Z-axis, forming a high-speed moving light spot in three-dimensional space. The servo motors driving the X-rotating galvanometer 24 and Y-rotating galvanometer 25 are driven by analog voltage, and the dynamic focusing mirror 22 performs reciprocating linear motion in the optical path direction to compensate for focusing errors, thereby ensuring that dynamic focusing is achieved in the Z-axis for real-time processing of three-dimensional curved parts during high-speed rotation.

[0037] In one embodiment, on the surface of the three-dimensional curved part 30, the position of the powder spot is offset by 0-3mm from the center of the laser spot in the direction of dragging the molten pool.

[0038] In one embodiment, the device also includes an inert gas protection chamber, in which the three-dimensional curved surface part 30, the drive assembly, the laser output assembly 20, and the laminar flow gas-carried powder high-speed deposition device are all housed.

[0039] This invention also provides a high-speed laser cladding deposition method, implemented using any of the high-speed laser cladding deposition apparatus described above, comprising the following steps: After completing the part model planning, the processing area is determined. The output head body 10 is fixed directly above the three-dimensional curved surface part 30 to be processed or at an inclination angle of no more than 20°. The laser output component 20 is offset from the output head body 10. The entire high-speed laser cladding deposition device is placed in an inert gas protection box. The preset path for forming scanning uses the area to be processed as the scanning base surface, and the area to be clad is obtained by reverse engineering the digital model or the original digital model. Layered slicing is performed with a layer thickness of 20-100μm, and the scanning overlap rate is 60-90%. Adjust the position of the central nozzle 12 to ensure that the position of the powder spot output by the central nozzle 12 is offset by 0-3mm from the center of the laser spot towards the direction of the molten pool; this solution can improve powder utilization, increase powder melting time, enhance powder melting effect, and at the same time ensure stable conveying of laminar powder without sharp edges.

[0040] Inert gas is turned on, and after the oxygen content is lower than 1000 PPM, the high-speed laser cladding deposition device is started. High-speed laser cladding deposition is carried out based on a preset path. The overall direction of the laser moves along the axis of the three-dimensional curved part 30. During the process, the dynamic focusing mirror 22 is driven to move to achieve dynamic focusing along the Z direction, ensuring that the laser focus point is always on the surface of the rotating three-dimensional curved part 30.

[0041] The following is a specific embodiment provided by the present invention: Taking the high-speed laser cladding process of a three-dimensional curved surface part 30 as an example, a laser powder deposition cladding technology is used to prepare a surface coating on the part. During the process, the laminar flow state of the powder is controlled. The specific implementation process is as follows: 1. After completing the part model planning, determine the area to be processed and fix it in place. Fix the output head body 10 directly above the three-dimensional curved surface part 30 to be processed or at an angle of no more than 20°. The position of the laser output component 20 output light source should avoid interference between the heat source and the output head body 10. The entire high-speed laser cladding deposition device is placed in an inert gas protective box.

[0042] 2. Design a laminar flow gas-carried powder high-speed deposition device, the specific structure of which is as follows: (1) The overall structure of the laminar air-carrying powder high-speed deposition device is an inverted cone shape. The cross-sectional view of the central powder delivery pipe 11, the first sheath gas delivery channel 13, and the second sheath gas delivery channel 14 is a "Y" shape. The laminar air-carrying powder high-speed deposition device is composed of three main components: the central input port cover 17, the output head body 10, and the cooling head 15. The central input port cover 17 has a hole drilled vertically downward at its center for air-carrying powder delivery / ultrasonic vibration powder delivery. Sheath gas is introduced into the upper part of the central input port cover 17 at the same time, and two sheath gas channels are introduced from the side into the central input port cover 17 through a one-way two-way system. The purpose is to ensure that the sheath gas is evenly dispersed inside the powder delivery head and to maintain the uniformity of the channel pressure. As the air-carrying powder / ultrasonic vibration powder and sheath gas are delivered, the channel is merged into one. The outer sheath gas envelops the inner air-carrying powder / ultrasonic vibration powder, offsetting and reducing the frictional resistance between the air-carrying powder / ultrasonic vibration powder and the inner wall of the channel, stabilizing the velocity gradient of the pipeline, and reducing the effective diameter and increasing the effective viscosity of the fluid.

[0043] (2) Whether the fluid flow is laminar or turbulent is mainly related to the Reynolds number. The Reynolds number integrates multiple factors affecting the fluid flow state. By matching the sheath gas pressure, the input gas pressure, the diameter of the pipe after mixing, the powder type, and the powder loading, a stable laminar powder flow is ultimately output. The Reynolds number is defined as follows: in, Indicates fluid density, Indicates the average flow velocity of the fluid. Indicates the characteristic length. This represents the dynamic viscosity. In this embodiment, the Reynolds number Re needs to be controlled to be less than 2300 to ensure laminar flow. Under laminar flow conditions, the velocity gradient (… ,in It's the flow rate. (Coordinates perpendicular to the flow direction) are relatively stable. The relative sliding of fluid components in each layer is relatively regular, with viscous forces playing a dominant role and velocity gradients... With viscous stress The relationship satisfies Newton's law of viscosity: In other words, the velocity gradient in laminar flow determines the magnitude of viscous stress, which in turn affects the flow resistance of the fluid. The dynamic viscosity of a fluid mainly depends on the type of fluid, temperature, and pressure. In conventional powder delivery nozzle systems, the gas pressure reaches 0.5-1 MPa. Without disturbing the fluid at the pipe wall, the powder flow velocity at the pipe wall is very low, resulting in an extremely high velocity gradient within the pipe. This velocity gradient change exceeds the range that laminar flow can stably maintain, causing a flow regime transition. The introduction of sheath gas primarily increases the flow velocity of the powder at the pipe wall, thus constraining the originally high-velocity and unevenly distributed mainstream fluid. This is equivalent to reducing the velocity gradient between the pipe wall and the center of the central nozzle 12, which is mainly reflected in the average fluid velocity at the Reynolds number. Firstly, the sheath gas reduces the effective viscosity of the fluid. Secondly, the introduction of sheath gas alters the boundary conditions of the fluid flow, reducing the actual occupied space and the effective value of the characteristic length of the entire flow region. Finally, the sheath gas and the central powder feed gas flow have a viscous interaction, which can effectively change the effective viscosity of the fluid. .

[0044] (3) Taking the air-carried powder of TC18 titanium alloy ceramic particle reinforced powder as an example, under the pressure of argon gas-carried powder, the dynamic viscosity μ of the fluid is approximately 1.79 × 10⁻⁶. -5 Pa·s, fluid density ρ is 1.1 kg / m³ 3 The effective pipe diameter d was 7 mm before and 5 mm after the introduction of sheath gas, and the average fluid velocity v was 20 m / s and 5 m / s, respectively. Substituting the Reynolds number calculations, the Reynolds numbers Re before and after the introduction of sheath gas were 8603 and 1536, respectively. These results suggest that after the introduction of sheath gas, the powder, which was originally flowing in a turbulent manner, achieved stable laminar flow transport.

[0045] 3. After the laser output component 20 is configured, the preset path of the forming scan takes the area to be processed as the scanning base surface, and uses the method of reverse engineering of digital model or the original digital model to obtain the area to be clad. The layer is sliced ​​with a layer thickness of 20-100μm and the scanning overlap rate is 60-90%.

[0046] 4. Select the nozzle shape of the center nozzle 12 as round / elliptical / pea pod shape, and adjust the nozzle position of the center nozzle 12 to ensure that the position of the powder spot is offset from the center of the laser source in the direction of dragging the molten pool by 0-3mm.

[0047] 5. Turn on the inert gas and wait until the oxygen content is below 1000 PPM. Then turn on the high-speed laser cladding deposition device and carry out laser processing based on the preset path. The laser moves at a low speed along the axis of the three-dimensional curved part 30. During the process, the dynamic focusing mirror 22 is driven by the servo motor driven by the analog voltage to achieve dynamic focusing along the height direction z, so as to ensure that the laser focus point is always on the surface of the high-speed rotating three-dimensional curved part 30.

[0048] 6. After the forming process is completed, turn off the high-speed laser cladding deposition device and wait for the three-dimensional curved surface part 30 to cool to room temperature before taking it out of the inert atmosphere protection box.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A laminar flow gas-carried powder high-speed deposition apparatus, characterized in that, include: The output head body has a central powder feeding pipe, a central nozzle, a first sheath gas delivery channel, and a second sheath gas delivery channel. The central nozzle is arranged along the central axis of the output head body. The central powder feeding pipe is connected to and coaxially arranged with the central nozzle. The first and second sheath gas delivery channels are both connected to the periphery of the central nozzle. The central powder feeding pipe is used to connect to a powder source, and the first and second sheath gas delivery channels are used to connect to a sheath gas source to form a powder laminar flow in the central nozzle. The powder laminar flow includes a powder flow conveyed along the central axis and sheath gas surrounding the powder flow.

2. The laminar flow gas-carried powder high-speed deposition apparatus as described in claim 1, characterized in that, The cross-sectional shape of the central nozzle is circular, elliptical, or pea-pod shaped.

3. The laminar flow gas-carried powder high-speed deposition apparatus as described in claim 1, characterized in that, It also includes a cooling head, which has a cooling channel for the flow of cooling medium, and the cooling head is threadedly connected to the output head body.

4. The laminar flow gas-carried powder high-speed deposition apparatus as described in claim 3, characterized in that, The cooling head is annular and has an internal thread. The cooling channel surrounds the internal thread, and the output head body has an external thread. The internal thread is threadedly connected to the external thread.

5. The laminar flow gas-carried powder high-speed deposition apparatus as described in claim 1, characterized in that, The Reynolds number Re of the powder laminar flow is less than or equal to 2300, and the gas velocity of the sheath gas is equal to the velocity of the powder flow.

6. A high-speed laser cladding deposition apparatus for performing high-speed laser cladding deposition of powder on the surface of three-dimensional curved parts, characterized in that, The device includes a drive assembly, a laser output assembly, and a laminar flow gas-carried powder high-speed deposition apparatus as described in any one of claims 1-5. The drive assembly is connected to the three-dimensional curved surface part and is used to drive the three-dimensional curved surface part to rotate along an axis. The laminar flow gas-carried powder high-speed deposition apparatus is used to deposit powder on the surface of the three-dimensional curved surface part to form powder spots. The laser output assembly is used to output laser light, and the laser light acts on the powder on the surface of the three-dimensional curved surface part.

7. The high-speed laser cladding deposition apparatus as described in claim 6, characterized in that, The laser output assembly includes a laser source, a dynamic focusing lens, a focusing lens, an X-axis rotating galvanometer, and a Y-axis rotating galvanometer. The laser source is used to output laser light. The dynamic focusing lens, the focusing lens, the X-axis rotating galvanometer, and the Y-axis rotating galvanometer are arranged sequentially along the optical path of the laser. The dynamic focusing lens is used to focus the laser light and can move along the optical path of the laser light. The focusing lens is used to focus the laser light. The X-axis rotating galvanometer is used to shift the position of the laser light in the X-axis direction, and the Y-axis rotating galvanometer is used to shift the position of the laser light in the Y-axis direction.

8. The high-speed laser cladding deposition apparatus as described in claim 6, characterized in that, On the surface of the three-dimensional curved part, the position of the powder spot is offset by 0-3mm from the center of the laser spot towards the direction of molten pool dragging.

9. The high-speed laser cladding deposition apparatus as described in claim 6, characterized in that, It also includes an inert gas protection box, in which the three-dimensional curved surface parts, the drive assembly, the laser output assembly, and the laminar flow gas-carried powder high-speed deposition device are all housed.

10. A high-speed laser cladding deposition method, implemented using the high-speed laser cladding deposition apparatus as described in any one of claims 6-9, characterized in that, Includes the following steps: After completing the part model planning, determine the area to be processed, fix the output head body directly above the three-dimensional curved surface part to be processed or at an angle of no more than 20°, set the laser output component and the output head body to be offset, and set the entire high-speed laser cladding deposition device in an inert gas protective box. The preset path for forming scanning uses the area to be processed as the scanning base surface, and the area to be clad is obtained by reverse engineering the digital model or the original digital model. Layered slicing is performed with a layer thickness of 20-100μm, and the scanning overlap rate is 60-90%. Adjust the position of the central nozzle to ensure that the position of the powder spot output by the central nozzle is offset by 0-3mm from the center of the laser spot in the direction of dragging the molten pool; Turn on the inert gas and wait until the oxygen content is below 1000 PPM. Then start the high-speed laser cladding deposition device and carry out high-speed laser cladding deposition based on the preset path. The overall direction of the laser moves along the axis of the three-dimensional curved part. During the process, the dynamic focusing lens is driven to move to achieve dynamic focusing along the Z direction, ensuring that the laser focus point is always on the surface of the rotating three-dimensional curved part.

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