Annular powder feeding nozzle and manufacturing method thereof

Abstract

The invention provides an annular powder feeding nozzle and a manufacturing method thereof, and belongs to the technical field of laser additive manufacturing parts. The annular powder feeding nozzle comprises an inner nozzle; the outer nozzle is arranged on the outer side of the inner nozzle in a surrounding mode, and an annular powder feeding channel is formed by the outer nozzle and the inner nozzle; the shunting rib plate is arranged in the annular powder feeding channel and is used for shunting the powder fed into the annular powder feeding channel step by step; and the cooling flow channel is arranged in the inner nozzle and the outer nozzle and is used for cooling the inner nozzle and the outer nozzle. And through the integrated design of the step-by-step shunting rib plates and the cooling flow channels, the powder distribution uniformity, the gravity interference resistance and the heat dissipation efficiency are remarkably improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of laser additive manufacturing parts, and particularly relates to a ring-shaped powder feeding nozzle and a manufacturing method thereof. BACKGROUND

[0002] In additive manufacturing processes such as laser cladding and laser metal deposition, the powder feeding nozzle is a key component that determines the forming quality.

[0003] Traditional ring-shaped powder feeding nozzles mostly adopt a split mechanical assembly structure, and the internal flow channel thereof is simple and lacks effective powder homogenization design. Such nozzles generally have problems such as uneven powder distribution and susceptibility to gravity, resulting in asymmetric cladding layers in actual application. Especially when processing small inclination angles or complex curved surfaces, the poor powder convergence seriously affects the deposition accuracy and forming efficiency. In addition, the connection interface of the split structure is prone to thermal deformation or even cracking under the long-term action of high-power laser, and the reliability is insufficient. At the same time, the cooling system design of the traditional nozzle is simple and the heat dissipation efficiency is low, which is difficult to meet the working condition requirements of high-power and long-time continuous operation. SUMMARY

[0004] In order to solve at least one of the technical problems in the background art, the application provides a ring-shaped powder feeding nozzle, which significantly improves the powder distribution uniformity, anti-gravity interference ability and heat dissipation efficiency through the integrated design of the step-by-step shunt rib plate and the cooling flow channel.

[0005] The second aspect embodiment of the application provides a ring-shaped powder feeding nozzle manufacturing method.

[0006] The technical scheme adopted by the application is as follows: The first aspect embodiment of the application provides a ring-shaped powder feeding nozzle, which comprises: an inner nozzle; an outer nozzle, which is arranged outside the inner nozzle and forms a ring-shaped powder feeding channel with the inner nozzle; a shunt rib plate, which is arranged in the ring-shaped powder feeding channel and is used for step-by-step shunting of the powder fed into the ring-shaped powder feeding channel; a cooling flow channel, which is arranged inside the inner nozzle and the outer nozzle and is used for cooling the inner nozzle and the outer nozzle.

[0007] According to the first aspect of the present application, the annular powder feeding nozzle is provided, which realizes fine and hierarchical regulation of the powder flow by coaxially nesting the inner nozzle and the outer nozzle to form an annular powder feeding channel and arranging multiple layers of step-up type shunt rib plates in the channel. Specifically, the powder enters from multiple powder feeding inlets and is continuously segmented by the rib plates, and finally forms multiple circumferentially uniformly distributed and axially penetrating powder sub-flow channels. This shunting mechanism not only greatly improves the uniformity of the powder distribution in the circumferential direction, but also effectively weakens the adverse effects of gravity on the powder trajectory, enabling the nozzle to work stably under small-angle conditions and significantly expanding the application capability of laser cladding in the repair of complex curved surfaces or nearly vertical surfaces. Meanwhile, the inner nozzle and the outer nozzle are both integrated with independent cooling channels, and the cooling medium can efficiently carry away the heat generated in the laser action area, avoiding deformation or failure of the nozzle due to heat accumulation and ensuring the stability of long-time high-power operation. More importantly, the entire nozzle structure, including the inner / outer nozzle, the shunt rib plate and the internal cooling channel, is integrally formed by selective laser melting additive manufacturing technology, and the components are metallurgically combined without welding or mechanical connection interface, which not only has high structural strength and good sealing performance, but also can realize complex internal flow channel geometry that cannot be processed by traditional processes. In summary, the annular powder feeding nozzle integrates high-uniform powder feeding, strong anti-interference capability, high-efficiency cooling and high-structural reliability, and solves the technical problems of easy clogging, uneven powder feeding, poor heat dissipation and difficulty in small-angle machining of existing split-type nozzles.

[0008] According to an embodiment of the present application, the shunt rib plates are sequentially arranged in four layers from top to bottom along the powder conveying direction, namely the first layer, the second layer, the third layer and the fourth layer; Each layer of the shunt rib plates is uniformly distributed in the annular powder feeding channel in the circumferential direction; Each layer of the shunt rib plates extends in the radial direction to connect the outer wall of the inner nozzle and the inner wall of the outer nozzle, thereby forming multiple circumferentially distributed and axially penetrating powder sub-flow channels in the annular powder feeding channel.

[0009] According to an embodiment of the present application, the first layer is provided with four shunt rib plates, each of which is located directly below the powder feeding inlet and is used to divide each incoming powder flow into two; The second layer is provided with eight shunt rib plates, the third layer is provided with sixteen shunt rib plates, and the fourth layer is provided with thirty-two shunt rib plates; From the second layer, the number of shunt rib plates of each layer is twice that of the previous layer, which is used to halve the powder flow output by the previous layer.

[0010] According to an embodiment of the present application, the thickness of the shunt rib plate is 0.5mm, the length is 10mm, and the axial spacing between adjacent two layers of the shunt rib plates is 0mm.

[0011] According to one embodiment of the present application, the cooling flow channel comprises a first spiral cooling channel built in the inner nozzle and a second spiral cooling channel built in the outer nozzle; The first spiral cooling channel and the second spiral cooling channel are independent of each other, and the inlet and outlet of the first spiral cooling channel and the second spiral cooling channel are located at the same end surface of the annular powder feeding nozzle.

[0012] According to one embodiment of the present application, the inner wall surface roughness Ra of the annular powder feeding channel is ≤1.6 μm; The flatness of the discharge port end surface of the annular powder feeding channel is not greater than 0.05 mm.

[0013] According to one embodiment of the present application, the inner nozzle is provided with an axial through laser channel; The discharge port end of the annular powder feeding channel is tapered and contracted.

[0014] The second aspect embodiment of the present application provides a manufacturing method of an annular powder feeding nozzle, which is used for manufacturing the annular powder feeding nozzle in any one of the first aspect embodiments described above, and comprises the following steps: A three-dimensional model comprising an inner nozzle, an outer nozzle, a shunt rib plate and a cooling flow channel is established; A 316L stainless steel powder with a particle size of 15 μm-53 μm is prepared, wherein the sphericity of the stainless steel powder is not less than 90%, and the loose bulk density is not less than 4.5 g / cm³; The three-dimensional model is introduced into a selective laser melting device, and in an inert gas environment with an oxygen content ≤100 ppm, the laser power is controlled to be 200 W-500 W, the scanning speed is controlled to be 800 mm / s-1500 mm / s, the layer thickness is controlled to be 20 μm-50 μm, and the scanning interval is controlled to be 50 μm-100 μm, the stainless steel powder is fused layer by layer, and the inner nozzle and the outer nozzle are integrally formed, wherein the shunt rib plate and the cooling flow channel are synchronously formed; The formed annular powder feeding nozzle is sequentially subjected to high-pressure gas blowing, ultrasonic cleaning, heat treatment and surface treatment.

[0015] According to one embodiment of the present application, the inert gas is argon or nitrogen.

[0016] According to one embodiment of the present application, the formed annular powder feeding nozzle is sequentially subjected to high-pressure gas blowing, ultrasonic cleaning, heat treatment and surface treatment, and specifically: The pressure of the high-pressure gas blowing is 0.5 MPa-1.0 MPa, which is used for removing the residual stainless steel powder in the annular powder feeding channel, the cooling flow channel and the shunt rib plate gap; The heat treatment is holding at 600-800℃ for 1-2h and then cooling down in the furnace. The inner wall of the annular powder feeding channel and the end face of the discharge port are treated by the abrasive flow polishing process, so that the surface roughness Ra of the inner wall of the annular powder feeding channel is less than or equal to 1.6μm, and the flatness of the end face of the discharge port is less than or equal to 0.05mm. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and serve to explain the principles of the application, and do not limit the application. In the drawings: Figure 1 A cross-sectional structure schematic diagram of the annular powder feeding nozzle provided by the embodiments of the application is shown in the drawings; Figure 2 A structure schematic diagram of the cooling flow channel provided by the embodiments of the application is shown in the drawings; Figure 3 A front view of the shunt rib plate provided by the embodiments of the application is shown in the drawings; Figure 4 A top view of the shunt rib plate provided by the embodiments of the application is shown in the drawings; Figure 5 A flowchart of the manufacturing method of the annular powder feeding nozzle provided by the embodiments of the application is shown in the drawings.

[0018] In the drawings, 11, inner nozzle; 111, first spiral cooling channel; 12, outer nozzle; 121, second spiral cooling channel; 13, annular powder feeding channel; 131, shunt rib plate; 1311, first layer; 1312, second layer; 1313, third layer; 1314, fourth layer; 14, laser channel; 2, inlet; 3, outlet. DETAILED DESCRIPTION

[0019] In order to more clearly illustrate the overall concept of the application, the following will be described in detail with reference to the accompanying drawings.

[0020] In the following description, many specific details are set forth in order to provide a thorough understanding of the application, but the application can be practiced in other ways different from those described herein, and therefore, the scope of protection of the application is not limited by the specific embodiments disclosed below. It should be noted that the embodiments of the application and the features in each embodiment can be combined with each other without conflict.

[0021] In addition, in the description of the present application, it needs to be understood that the terms "top", "bottom", "inner", "outer", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0022] In the present application, unless specifically defined and limited otherwise, the terms "mount", "connect", "connect", "fix", and the like should be broadly understood, for example, can be fixed connection, can also be detachable connection, or integrated; can be mechanical connection, can also be electrical connection, can also be communication; can be directly connected, can also be indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0023] In the present application, unless specifically defined and limited otherwise, the first feature is "on" or "under" the second feature. The first and second features can be in direct contact, or the first and second features can be indirectly in contact through an intermediate medium. In the description of the specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples.

[0024] As shown in Figures 1 to 4 The first aspect of the present application provides an annular powder feeding nozzle, comprising: an inner nozzle 11; an outer nozzle 12, which is arranged outside the inner nozzle 11 and forms an annular powder feeding channel 13 with the inner nozzle 11; a shunt rib plate 131, which is arranged in the annular powder feeding channel 13 and is used for gradually shunting the powder fed into the annular powder feeding channel 13; a cooling flow channel, which is arranged inside the inner nozzle 11 and the outer nozzle 12 and is used for cooling the inner nozzle 11 and the outer nozzle 12.

[0025] The inner nozzle 11 is a centrally located cylindrical structure, which can be provided with a laser channel 14 inside for coaxially introducing a laser beam; the outer nozzle 12 is concentrically sleeved outside the inner nozzle 11, and an annular cavity, i.e. an annular powder feeding channel 13, is formed between the two, serving as the main path for the metal powder to be transported from the inlet to the outlet. Inside the channel, a plurality of layers of shunt rib plates 131 are arranged along the powder flow direction, which are connected to the outer wall of the inner nozzle 11 and the inner wall of the outer nozzle 12 in the radial direction, not only serving to support and enhance the structural rigidity, but more importantly, gradually and exponentially dividing the incoming powder flow (e.g. 4→8→16→32), so that the powder is more evenly distributed in the circumferential direction, and the segregation phenomenon caused by gravity is effectively weakened. In addition, independent cooling channels are embedded in the walls of the inner nozzle 11 and the outer nozzle 12, respectively, and the cooling medium can enter and exit from the same end face, efficiently removing the heat generated during laser processing, preventing the nozzle from deforming due to heat and affecting the powder feeding accuracy or causing structural failure. All the above components are integrally formed by additive manufacturing technology, with no assembly gap, and have complex internal flow channel manufacturability and excellent thermal-mechanical properties, significantly improving the reliability and process adaptability of the nozzle under harsh working conditions such as high power, long time and small angle laser cladding.

[0026] According to the annular powder feeding nozzle provided by the first aspect of the present application, the inner nozzle 11 and the outer nozzle 12 are coaxially nested to form the annular powder feeding channel 13, and a plurality of layers of shunt rib plates 131 are arranged in the channel to realize fine and hierarchical regulation of the incoming powder flow. Specifically, after the powder enters from the multiple powder feeding inlets, it is continuously divided by the rib plates layer by layer, and finally forms a plurality of powder sub-channels that are evenly distributed in the circumferential direction and axially through. This shunting mechanism not only greatly improves the uniformity of the powder distribution in the circumferential direction, but also effectively weakens the adverse effects of gravity on the powder trajectory, enabling the nozzle to work stably under small angle conditions and significantly expanding the application capability of laser cladding in the repair of complex curved surfaces or nearly vertical surfaces. At the same time, the inner nozzle 11 and the outer nozzle 12 are both integrated with independent cooling channels inside, and the cooling medium can efficiently remove the heat generated in the laser action area, avoiding deformation or failure of the nozzle due to heat accumulation, and ensuring the stability of long-time high-power operation. More importantly, the entire nozzle structure, including the inner / outer nozzle 12, the shunt rib plate 131 and the internal cooling channel, is integrally formed by selective laser melting additive manufacturing technology, and the components are metallurgically bonded without welding or mechanical connection interfaces, which not only has high structural strength and good sealing performance, but also can realize complex internal flow channel geometries that cannot be processed by traditional processes. In summary, the annular powder feeding nozzle integrates high uniform powder feeding, strong anti-interference capability, efficient cooling and high structural reliability, solving the technical problems of existing split-type nozzles such as easy clogging, uneven powder feeding, poor heat dissipation and difficulty in small angle machining.

[0027] As Figures 3 to 4As shown, in some embodiments of this application, the flow divider rib 131 is arranged in four layers from top to bottom along the powder conveying direction, namely the first layer 1311, the second layer 1312, the third layer 1313 and the fourth layer 1314. Each layer of diversion ribs 131 is evenly distributed circumferentially within the annular powder feeding channel 13; Each layer of flow divider ribs 131 extends radially to connect the outer wall of the inner nozzle 11 with the inner wall of the outer nozzle 12, thereby forming multiple circumferentially distributed and axially connected powder sub-channels in the annular powder feeding channel 13.

[0028] This structure is based on the principle of "step-by-step multiplication and diversion": after the powder enters from the upper powder inlet, the initial flow is initially divided by the first layer 1311 rib plate; subsequently, the second layer 1312, the third layer 1313, and the fourth layer 1314 rib plates sequentially divide the powder flow output from the previous layer in half again, so that the powder undergoes four consecutive fine distributions during axial transmission. This hierarchical, geometrically multiplying diversion mechanism not only significantly improves the uniformity of powder distribution in the circumferential direction, but also disperses local aggregation caused by gravity or airflow disturbances through multiple disturbances, effectively suppressing the "powder deviation" or "accumulation" phenomena commonly seen during cladding. More importantly, since each layer of rib plates is radially connected to the inner and outer nozzles 12, the resulting powder sub-channels are axially straight and circumferentially symmetrical, ensuring that each stream of powder arrives at the outlet synchronously with a consistent path length and flow resistance, thereby guaranteeing a high degree of consistency in the ejection direction. This design is particularly suitable for laser cladding scenarios with small tilt angles or even near-vertical surfaces, overcoming the technical bottleneck of traditional nozzles causing a decline in forming quality due to gravity under non-horizontal conditions.

[0029] Meanwhile, the multi-layer stiffening plates also enhance the structural rigidity, and combined with the one-piece molding process, further improve the nozzle's resistance to deformation under high heat load.

[0030] like Figures 3 to 4 As shown, in some embodiments of this application, the first layer 1311 is provided with four diversion ribs 131, each diversion rib 131 being located directly below the powder inlet, used to divide each incoming powder flow into two. The second layer 1312 is provided with 8 diversion ribs 131, the third layer 1313 is provided with 16 diversion ribs 131, and the fourth layer 1314 is provided with 32 diversion ribs 131. Starting from the second layer 1312, the number of flow divider ribs 131 in each layer is twice that of the previous layer, which is used to divide the powder flow output from the previous layer in half.

[0031] Specifically, the first layer 1311 is provided with 4 shunt ribs 131, which are accurately positioned just below the four powder feeding inlets, so that each concentrated powder flow entering from the inlet is symmetrically divided into two in the initial stage, forming 8 preliminary homogenized sub-flows; then, the second layer 1312 is configured with 8 ribs, which are just located at the center of the shunt gaps of the first layer 1311, and divide the 8 powder flows into 16 again; the third layer 1313 continues to subdivide the output of the upper layer with 16 ribs, obtaining 32; and the fourth layer 1314 finally completes the fine distribution with 32 ribs, so that the powder reaches a highly uniform circumferential distribution at the outlet of the annular channel. This "4→8→16→32" step-by-step multiplication structure is not simply increasing the number of ribs. Each layer of ribs is accurately inserted into the center line position between adjacent ribs of the previous layer, realizing equal redistribution of the powder flow of the previous stage, thereby effectively breaking the unevenness and inertial aggregation of the initial flow.

[0032] The spatial distribution consistency of the powder in the circumferential direction is significantly improved, and the influence of factors such as gravity settlement and airflow disturbance on the stability of powder feeding is greatly weakened, which is especially suitable for small inclination angle, complex curved surface or high-precision laser cladding scenes.

[0033] In some embodiments of the present application, the thickness of the shunt rib 131 is 0.5 mm, the length is 10 mm, and the axial spacing between the adjacent two layers of shunt ribs 131 is 0 mm.

[0034] Among them, the thin rib of 0.5 mm significantly reduces the blocking area of the gas-powder two-phase flow on the premise of effectively separating the powder flow channel and realizing accurate shunting, reduces the flow resistance and turbulent disturbance, and avoids powder accumulation or nozzle blockage caused by local congestion; the radial length of 10 mm ensures that the rib can stably connect the outer wall of the inner nozzle 11 and the inner wall of the outer nozzle 12, forming reliable mechanical support and improving the overall heat deformation resistance of the nozzle; most importantly, the axial spacing between the adjacent two layers of ribs is 0 mm (i.e. the axial projection lines of the upper and lower layers are closely connected), so that there is no stagnation gap when the powder passes through each shunt level, realizing a continuous and seamless step-by-step segmentation process. This "zero spacing" arrangement not only strengthens the continuity and efficiency of multi-stage shunting, but also avoids the dead zones or vortex zones that may occur in the traditional stepped layout, further improving the stability of powder conveying and the uniformity of outlet distribution.

[0035] As shown in Figures 1 to 2 In some embodiments of the present application, the cooling channel includes a first spiral cooling channel 111 built in the inner nozzle 11, and a second spiral cooling channel 121 built in the outer nozzle 12; The first spiral cooling channel 111 and the second spiral cooling channel 121 are independent of each other, and the inlet 2 and the outlet 3 of the first spiral cooling channel 111 and the second spiral cooling channel 121 are located on the same end surface of the annular powder feeding nozzle.

[0036] The two groups of cooling channels are isolated from each other and are not connected to each other, and can be respectively connected to cooling medium (such as deionized water or coolant), so that the overall heat dissipation is not invalid due to single-point blockage or uneven pressure drop, and the reliability and fault tolerance of the cooling system are significantly improved.

[0037] More importantly, the inlet 2 and the outlet 3 of the two spiral channels are arranged on the same end surface of the annular powder feeding nozzle, and the "same-end inlet and outlet" design greatly simplifies the external pipeline connection structure, facilitates the quick docking with the cooling interface of the laser processing head, and avoids the pipe connection difficulty problem of the traditional opposite inlet and outlet layout in the narrow installation space. The spiral flow channel itself has the characteristics of long flow process, uniform flow rate and large heat exchange area, which can make the cooling medium fully cover the high-temperature area along the nozzle axis (especially the outlet section close to the laser action area), realize uniform and efficient heat dissipation of the inner and outer nozzle 12 wall body, and effectively inhibit the problems of thermal deformation, material creep or powder sintering adhesion caused by local overheating.

[0038] In some embodiments of the present application, the inner wall surface roughness Ra of the annular powder feeding channel 13 is ≤1.6 μm; The flatness of the discharge port end surface of the annular powder feeding channel 13 is not greater than 0.05 mm.

[0039] The metal powder frequently contacts the inner wall of the channel during the conveying process. If the surface roughness is too high (such as Ra>3.2 μm), the friction resistance will be significantly increased, which will cause poor powder flow, local accumulation and even sintering adhesion. In addition, the rough surface is easy to form micro-eddy current or stagnation area, which will destroy the uniformity of the gas-powder two-phase flow. By controlling the inner wall roughness to be Ra≤1.6 μm (equivalent to the precision grinding or polishing level), the friction coefficient between the powder and the wall can be greatly reduced, so that the powder can smoothly and stably pass through the entire annular channel under the driving of the carrier gas, which is especially beneficial to the efficient conveying of fine particle size powder (such as 15-45 μm). In addition, the flatness of the discharge port end surface directly affects the consistency of the outlet direction of each powder sub-flow. If there is warping or height difference (such as more than 0.1 mm) on the end surface, the outlet of part of the flow channel will be advanced or delayed, which will cause the divergence and deflection of the powder beam, and then affect the quality of the molten pool forming. By strictly controlling the flatness to be ≤0.05 mm (for example, the measured value is 0.03 mm), it can ensure that the 32 powder sub-flows are synchronously sprayed on almost the same plane with high parallelism, so as to form a dense, symmetrical and clear profile on the workpiece surface.

[0040] Taking an actual application as an example, when the nozzle is used for laser cladding of Inconel 718 alloy at a small angle (10°), due to the inner wall Ra = 1.2 μm and the flatness of the discharge port reaching 0.03 mm, the cladding layer width deviation is reduced from ± 0.3 mm of the traditional nozzle to ± 0.08 mm, and the forming repeatability is significantly improved.

[0041] In summary, the above surface precision control not only optimizes the powder flowability and jet consistency, but also directly supports the implementation of high-precision, small-angle and complex-path cladding processes.

[0042] As shown in Figure 1 In some embodiments of the present application, an axial through laser channel 14 is arranged at the center of the inner nozzle 11. The discharge port end of the annular powder feeding channel 13 is in a tapered shrinkage structure.

[0043] The laser channel 14 is used to coaxially introduce a high-energy laser beam, which is accurately focused on the workpiece surface below the outlet of the annular powder feeding channel 13. At the same time, the discharge port end of the annular powder feeding channel 13 is designed as a tapered shrinkage structure, so that the powder flow originally distributed in a ring shape gradually converges to the center near the outlet.

[0044] The laser beam passes along the central axis without obstruction, while the annularly transported metal powder is guided through the tapered shrinkage section to form a dense and symmetrical powder convergence cone at the laser focal point, significantly improving the capture rate and utilization rate of the powder in the molten pool. The tapered shrinkage structure can also accelerate the powder outlet speed, reduce the divergence angle, and make the powder beam more concentrated, thereby obtaining a narrower and higher aspect ratio cladding path, which is particularly suitable for precision repair or thin-walled structure forming.

[0045] As shown in Figure 5 The second aspect embodiment of the present application provides a manufacturing method of an annular powder feeding nozzle, for manufacturing the annular powder feeding nozzle in any of the above first aspect embodiments, comprising: Step 100, establishing a three-dimensional model comprising an inner nozzle 11, an outer nozzle 12, a shunt rib plate 131 and a cooling flow channel.

[0046] Step 200, preparing 316L stainless steel powder with a particle size of 15 μm to 53 μm, wherein the sphericity of the stainless steel powder is not less than 90%, and the loose bulk density is not less than 4.5 g / cm³.

[0047] Step 300, import the three-dimensional model into the selective laser melting device, control the laser power to be 200W-500W, the scanning speed to be 800mm / s-1500mm / s, the layer thickness to be 20μm-50μm, and the scanning interval to be 50μm-100μm in the inert gas environment with oxygen content ≤100ppm, and melt the stainless steel powder layer by layer to integrally form the inner nozzle 11 and the outer nozzle 12, wherein the shunt rib plate 131 and the cooling runner are synchronously formed.

[0048] Step 400, sequentially perform high-pressure gas purging, ultrasonic cleaning, heat treatment and surface treatment on the formed annular powder feeding nozzle.

[0049] Step 100 involves the construction of a three-dimensional model, which is the basis of the entire manufacturing process. The model integrates all functional features such as inner nozzle 11, outer nozzle 12, four-layer step-up shunt rib plate 131 (such as 4→8→16→32 layout), double-helix cooling runner, central laser channel 14, and outlet taper contraction structure, and ensures geometric continuity and non-interference of internal flow channels.

[0050] Step 200 focuses on the precise control of raw materials. 316L stainless steel powder with a particle size of 15μm-53μm is selected, which takes into account good flowability and high bulk density; at the same time, the sphericity is not less than 90% (i.e. most particles are close to ideal spheres), to ensure uniform powder laying and molten pool stability; the loose bulk density is not less than 4.5g / cm³, which reflects the high dense packing ability of the powder, helping to reduce porosity during the forming process and improve the mechanical properties and density of the final part.

[0051] Step 300 is the core forming stage. The optimized three-dimensional model is imported into the selective laser melting (SLM) device, and printing is performed in an argon or nitrogen protective atmosphere with oxygen content ≤100ppm, effectively preventing oxidation of the metal powder during high-temperature melting. By precisely controlling the laser power (200W-500W), scanning speed (800mm / s-1500mm / s), layer thickness (20μm-50μm), and scanning interval (50μm-100μm), the size of the molten pool, the overlap rate, and the heat input are precisely controlled, thereby integrally forming the overall structure including the shunt rib plate 131 (only 0.5mm thick), the micro cooling runner, and the complex internal cavity, without any subsequent welding or assembly, eliminating the risk of interface failure of traditional split structures.

[0052] Step 400 is a post-processing process aimed at improving the part functionality and surface quality. First, high-pressure gas purging is used to completely remove the unmelted powder remaining in the narrow annular channel, cooling channel and gap between the shunt rib 131; then ultrasonic cleaning is used to remove surface impurities; then the part is kept at a preset temperature for a preset time and cooled in the furnace to eliminate residual stress caused by SLM rapid solidification and prevent deformation and cracking in use; finally, special polishing techniques such as abrasive flow are used to finish the inner wall of the annular powder feeding channel 13 and the end face of the discharge port to achieve a surface roughness of Ra≤1.6μm and an end face flatness of ≤0.05mm, respectively, ensuring smooth powder flow and high consistency of the spray direction.

[0053] In one embodiment of the present application, the manufacturing process of the annular powder feeding nozzle uses the following parameters: 316L stainless steel powder with a particle size of 45μm (sphericity of 92%, bulk density of 4.6g / cm³) is selected and loaded into the selective laser melting equipment; under the protection of high-purity argon with an oxygen content of 80ppm, the laser power is set to 350W, the scanning speed is 1200mm / s, the layer thickness is 30μm, and the scanning pitch is 70μm, and the powder is melted and formed layer by layer. After forming, the inner cavity is cleaned by high-pressure nitrogen blowing at 0.8MPa to remove residual powder, and then ultrasonic cleaning is performed; then the part is kept at 700℃ for 1.5 hours and cooled in the furnace to eliminate stress; finally, abrasive flow polishing is used to make the roughness of the inner wall of the annular powder feeding channel 13 reach Ra=1.2μm, and the end face flatness of the discharge port is measured to be 0.03mm.

[0054] According to the annular powder feeding nozzle manufacturing method provided by the second aspect of the present application, through the cooperation of three-dimensional modeling, strictly controlled 316L stainless steel powder performance parameters and optimized selective laser melting process parameters, the integrated assembly-free forming of the inner nozzle 11, the outer nozzle 12, the four-layer step-by-step multiplication type shunt rib 131 and the double helix cooling channel is successfully realized, avoiding the leakage, deformation or interface failure problems caused by welding or mechanical connection of traditional split structure; combined with systematic post-processing procedures such as high-pressure purging, heat treatment and abrasive flow finishing, not only effectively removes internal residual powder and eliminates residual stress, but also makes the roughness of the inner wall of the annular powder feeding channel 13 stable to reach Ra≤1.6μm, and the end face flatness of the discharge port ≤0.05mm, significantly improving the stability of powder flow and the consistency of the spray direction.

[0055] In some embodiments of the present application, the inert gas is argon or nitrogen. It is intended to provide a high-purity, low-oxygen protective atmosphere for the selective laser melting forming process. Among them, argon is extremely stable in chemical properties, and its density is greater than that of air, which can effectively cover the molten pool area, prevent the oxidation or nitridation of 316L stainless steel powder during high-temperature melting, and is especially suitable for high-alloy materials sensitive to oxygen; nitrogen is low in cost and easy to obtain, and under the premise of strict control of oxygen content (≤100 ppm), it can also meet the forming protection requirements of 316L stainless steel. Both of them can significantly inhibit the reaction of metal vapor and environmental gas, reduce defects such as spheroidization, porosity and inclusion, and ensure the density and forming precision of the complex flow channel (such as the split rib plate 131, the cooling channel) inside the nozzle, thereby ensuring the mechanical properties and functional reliability of the final product.

[0056] In some embodiments of the present application, the annular powder feeding nozzle after forming is sequentially subjected to high-pressure gas blowing, ultrasonic cleaning, heat treatment and surface treatment, specifically: The pressure of high-pressure gas blowing is 0.5MPa~1.0MPa, which is used to remove the residual stainless steel powder in the annular powder feeding channel 13, the cooling flow channel and the gap between the split rib plate 131; The heat treatment is to heat at 600℃~800℃ for 1h~2h and then cool in the furnace; The abrasive flow polishing process is adopted to treat the inner wall of the annular powder feeding channel 13 and the end face of the discharge port, so that the surface roughness Ra of the inner wall of the annular powder feeding channel 13 is ≤1.6μm, and the flatness of the end face of the discharge port is ≤0.05mm.

[0057] Firstly, high-pressure gas blowing with a pressure of 0.5MPa~1.0MPa can effectively penetrate the narrow annular powder feeding channel 13, the spiral cooling flow channel and the gap between the multi-layer split rib plate 131 which is only 0.5mm thick, and completely remove the residual unmelted or semi-melted 316L stainless steel powder in the SLM forming process, avoiding uneven powder feeding or cooling failure caused by powder blockage in subsequent use; then ultrasonic cleaning is carried out to further remove micrometer-sized particles and surface contaminants, ensuring the cleanliness of the internal flow channel. Next, through the heat treatment process of heating at 600℃~800℃ for 1h~2h and then cooling in the furnace, the residual stress generated in the additive manufacturing process due to rapid solidification is fully released, preventing the nozzle from warping, cracking or size drift under long-time operation of high-power laser, significantly improving its structural stability and service life. Finally, the abrasive flow polishing process is adopted to precisely finish the key functional surfaces: this process uses flexible abrasive media to flow through the complex internal cavity under pressure driving, uniformly grinding the inner wall of the annular powder feeding channel 13 and the end face of the discharge port, finally making the surface roughness of the inner wall stable at Ra≤1.6μm, greatly reducing the powder conveying resistance; at the same time, the flatness of the end face of the discharge port is controlled at ≤0.05mm, realizing the synchronous and same-direction ejection of 32 powder sub-flows.

[0058] For any parts not mentioned in this application, existing technologies may be used or referenced.

[0059] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0060] The above description is merely an embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A ring-shaped powder feed nozzle, characterized in that The application relates to a powder feeding nozzle, which comprises the following parts: an inner nozzle (11); an outer nozzle (12) arranged outside the inner nozzle (11) and forming an annular powder feeding channel (13) with the inner nozzle (11); a shunt baffle (131) arranged in the annular powder feeding channel (13) and used for gradually shunting the powder fed into the annular powder feeding channel (13); and a cooling flow channel arranged inside the inner nozzle (11) and the outer nozzle (12) and used for cooling the inner nozzle (11) and the outer nozzle (12). The shunt baffles (131) are arranged in four layers from top to bottom along the powder conveying direction, namely a first layer (1311), a second layer (1312), a third layer (1313) and a fourth layer (1314). Each layer of the shunt baffles (131) is uniformly distributed in the annular powder feeding channel (13) along the circumferential direction. Each layer of the shunt baffles (131) extends along the radial direction and connects the outer wall of the inner nozzle (11) and the inner wall of the outer nozzle (12), so that a plurality of powder sub-flow channels, which are uniformly distributed along the circumferential direction and axially penetrate, are formed in the annular powder feeding channel (13). The first layer (1311) is provided with four shunt baffles (131), and each shunt baffle (131) is located directly below the powder feeding inlet and is used for dividing each powder flow into two.

2. The ring-shaped powder feed nozzle of claim 1, wherein The second layer (1312) is provided with eight shunt baffles (131), the third layer (1313) is provided with 16 shunt baffles (131), and the fourth layer (1314) is provided with 32 shunt baffles (131). The number of shunt baffles (131) in each layer is twice that of the previous layer, and the powder flow output by the previous layer is halved. The thickness of the shunt baffles (131) is 0.5 mm, the length is 10 mm, and the axial spacing between adjacent two layers of the shunt baffles (131) is 0 mm.

3. The ring-shaped powder feed nozzle of claim 2, wherein, The cooling flow channel comprises a first spiral cooling channel (111) arranged in the inner nozzle (11) and a second spiral cooling channel (121) arranged in the outer nozzle (12). The first spiral cooling channel (111) and the second spiral cooling channel (121) are independent of each other, and the inlet (2) and the outlet (3) of the first spiral cooling channel (111) and the second spiral cooling channel (121) are located on the same end surface of the annular powder feeding nozzle. The inner wall surface roughness Ra of the annular powder feeding channel (13) is less than or equal to 1.6 microns.

4. The ring-shaped powder feed nozzle of claim 3, wherein The flatness of the discharge port end surface of the annular powder feeding channel (13) is not greater than 0.05 mm.

5. The annular powder feed nozzle of claim 1 wherein, The inner nozzle (11) is provided with an axially penetrating laser channel (14) in the center. The discharge port end of the annular powder feeding channel (13) is tapered and contracted.

6. The annular powder feed nozzle of claim 1 wherein, The application further relates to a three-dimensional model of the powder feeding nozzle. ​ 7. The ring-shaped powder feed nozzle of claim 6, wherein ​ ​ 8. A manufacturing method of a ring-shaped powder feeder nozzle for manufacturing the ring-shaped powder feeder nozzle according to any one of claims 1 to 7, characterized by, ​ ​ The application discloses a 316L stainless steel powder with a particle size of 15-53 microns, wherein the sphericity of the stainless steel powder is not less than 90%, and the loose bulk density is not less than 4.5 g / cm3. The three-dimensional model is introduced into a selective laser melting device, and the stainless steel powder is integrally formed into the inner nozzle (11) and the outer nozzle (12) by layer-by-layer melting under the inert gas environment with an oxygen content of not more than 100 ppm, the laser power of 200-500 W, the scanning speed of 800-1500 mm / s, the layer thickness of 20-50 microns and the scanning interval of 50-100 microns, and the flow distribution rib plate (131) and the cooling flow channel are synchronously formed. The formed annular powder feeding nozzle is sequentially subjected to high-pressure gas blowing, ultrasonic cleaning, heat treatment and surface treatment.

9. The ring-shaped powder feed nozzle manufacturing method according to claim 8, characterized by The inert gas is argon or nitrogen.

10. The ring-shaped powder feed nozzle manufacturing method according to claim 8, characterized by The high-pressure gas blowing is performed at a pressure of 0.5-1.0 MPa, and is used for removing the residual stainless steel powder in the annular powder feeding channel (13), the cooling flow channel and the gap of the flow distribution rib plate (131). The heat treatment is heat preservation at 600-800 DEG C for 1-2 hours and then furnace cooling. The inner wall of the annular powder feeding channel (13) and the end face of the discharge port are treated by using a abrasive flow polishing process, so that the surface roughness Ra of the inner wall of the annular powder feeding channel (13) is not more than 1.6 microns, and the flatness of the end face of the discharge port is not more than 0.05 mm. ​

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