WO2022083681A1 - 具有自净功能的内壁增材制造同轴送粉喷嘴 - Google Patents

具有自净功能的内壁增材制造同轴送粉喷嘴 Download PDF

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Publication number
WO2022083681A1
WO2022083681A1 PCT/CN2021/125247 CN2021125247W WO2022083681A1 WO 2022083681 A1 WO2022083681 A1 WO 2022083681A1 CN 2021125247 W CN2021125247 W CN 2021125247W WO 2022083681 A1 WO2022083681 A1 WO 2022083681A1
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WIPO (PCT)
Prior art keywords
powder
self
wall
partition
inlet
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Ceased
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PCT/CN2021/125247
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English (en)
French (fr)
Inventor
顾冬冬
石新宇
历彦泽
戴冬华
葛庆
孙宜璇
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Nanjing University of Aeronautics and Astronautics
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Nanjing University of Aeronautics and Astronautics
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Priority to US18/000,830 priority Critical patent/US11826827B2/en
Publication of WO2022083681A1 publication Critical patent/WO2022083681A1/zh
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F12/00—Apparatus or devices specially adapted for additive manufacturing; Auxiliary means for additive manufacturing; Combinations of additive manufacturing apparatus or devices with other processing apparatus or devices
    • B22F12/50—Means for feeding of material, e.g. heads
    • B22F12/53—Nozzles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y30/00—Apparatus for additive manufacturing; Details thereof or accessories therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/14—Working by laser beam, e.g. welding, cutting or boring using a fluid stream, e.g. a jet of gas, in conjunction with the laser beam; Nozzles therefor
    • B23K26/1462—Nozzles; Features related to nozzles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
    • B29C64/30—Auxiliary operations or equipment
    • B29C64/35—Cleaning
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C24/00—Coating starting from inorganic powder
    • C23C24/08—Coating starting from inorganic powder by application of heat or pressure and heat
    • C23C24/10—Coating starting from inorganic powder by application of heat or pressure and heat with intermediate formation of a liquid phase in the layer
    • C23C24/103—Coating with metallic material, i.e. metals or metal alloys, optionally comprising hard particles, e.g. oxides, carbides or nitrides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
    • B22F10/20—Direct sintering or melting
    • B22F10/25—Direct deposition of metal particles, e.g. direct metal deposition [DMD] or laser engineered net shaping [LENS]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F12/00—Apparatus or devices specially adapted for additive manufacturing; Auxiliary means for additive manufacturing; Combinations of additive manufacturing apparatus or devices with other processing apparatus or devices
    • B22F12/70—Gas flow means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
    • B29C64/20—Apparatus for additive manufacturing; Details thereof or accessories therefor
    • B29C64/205—Means for applying layers
    • B29C64/209—Heads; Nozzles
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

Definitions

  • the invention relates to a nozzle with self-cleaning function and a system thereof, belonging to the field of laser processing.
  • Laser cladding is one of the more important and widely used technologies.
  • Laser cladding also known as laser cladding, mainly includes surface modification of materials, repair and regeneration of workpieces and 3D rapid prototyping.
  • the substrate and the cladding material are melted, and the two are combined and solidified to form an additive cladding layer.
  • the processing process compared with the traditional process, it has lower input heat, smaller heat affected zone, smaller deformation degree and finer structure, so it is widely used in aerospace, military, industry, agriculture and other fields.
  • Existing cladding can be roughly divided into pre-coating and synchronous powder feeding.
  • the pre-coating and cladding process is complex, it is not easy to process on complex surfaces, and the dilution rate is difficult to control.
  • Synchronous powder feeding is roughly divided into two categories: lateral powder feeding and coaxial powder feeding. Lateral powder feeding is difficult to obtain a relatively stable overlapping area of the laser and powder action area, and it is difficult to process the route with folded angles and arcs.
  • the coaxial spraying improves the utilization rate of the powder, reduces the dilution rate, improves the accuracy and controllability of the cladding process, and makes the processing route more flexible through the real-time convergence of the powder and the laser beam. change, which provides conditions for laser rapid prototyping by powder spraying.
  • the inner wall protective layer is also required to be clad in the narrow and long metal pipes.
  • the wear resistance and corrosion resistance of the inner wall of the metal pipe are increased.
  • the inner wall of the metal tube needs to be manufactured through a coaxial nozzle. Additive manufacturing of inner walls of 3D structures.
  • the best machining position for the coaxial nozzle is perpendicular to the ground, just above the substrate by one focal length of the powder beam, and the nozzle is vertically downward for the inner wall additive manufacturing.
  • the powder is prone to segregation.
  • additive manufacturing is performed on the inner wall of the metal tube, due to the action of gravity, the powder that is not used during the processing will slide down to the bottom of the tube along both sides of the inner wall. If it is not cleaned or collected in time, the inner wall will be formed during the additive manufacturing process.
  • the regional powder accumulates and is submerged by it, and it is difficult to control the key forming process parameters such as the actual inner wall cladding powder volume, molten pool depth, dilution rate, etc., which greatly reduces the cladding quality.
  • the key forming process parameters such as the actual inner wall cladding powder volume, molten pool depth, dilution rate, etc., which greatly reduces the cladding quality.
  • the nozzle is inclined to avoid the bottom of the pipe for processing, it is difficult to guarantee the quality of cladding due to the poor quality of powder convergence.
  • the high-temperature metal cooling process will have a significant dimensional shrinkage effect, which greatly reduces the dimensional accuracy of the complex structure of the inner wall and significantly prolongs the manufacturing cycle. Therefore, in the process of inner wall additive manufacturing, designing inner wall nozzles with self-cleaning function has obvious economic and social benefits for efficient and high-quality inner wall additive manufacturing.
  • the main purpose of the present invention is to solve the problems that powder is not used to accumulate in the metal tube during the current inner wall additive manufacturing process, which affects the processing and is difficult to clean, and provides a self-cleaning device with self-cleaning ability under the environmental conditions of the inner wall additive material. Shaft feeding nozzle.
  • An inner wall additive manufacturing coaxial powder feeding nozzle with self-cleaning function comprising a nozzle body, the nozzle body comprising a partition type shell, a powder flow area, a cooling liquid flow area and a protective gas conveying flow channel; Partition a, Partition b; Partition b is located on the outside of Partition a, the powder flow area is set in Partition a, and the cooling liquid flow area is set in Partition wall b; A cooling liquid inlet; a powder self-cleaning filter is arranged on the outer side of the partition-type housing;
  • the powder self-cleaning filter is allocated with a group of powder collection pipes on both sides of the partition shell in the axial direction; each group of powder collection pipes includes at least one powder collection pipe;
  • the powder collecting tube has a two-section structure, including an upper tube section arranged in a straight tube shape and a lower tube section arranged in a curved tube shape.
  • the connecting head can be connected with the powder collecting system, and the lower end of the lower pipe section is the residual powder inlet, which is arranged below the metal pipeline to be processed and is located at the axial outer side of the powder gathering point of the metal pipeline to be processed;
  • the residual powder inlet of each powder collecting pipe can promote the residual powder on the opposite side to roll down the wall of the metal pipe to be processed on the same side to the and converge at the front end of the residual powder inlet of the powder collection tube, the residual powder inlet of the powder collection tube can collect the residual powder at its front end under the suction force exerted by the powder collection system.
  • the distance h of the residual powder inlet relative to the bottom of the metal pipe to be processed satisfies:
  • d s represents the maximum particle size of the powder particles
  • ⁇ s is the density of the powder particle material
  • ⁇ is the density of the transport gas.
  • the radius R of the residual powder inlet satisfies:
  • n represents the number of powder inlets connected to the powder flow area; r is the radius of the powder inlet; ⁇ represents the volume fraction of the residual powder particles in the total powder particles passed through each powder inlet.
  • the trajectory profile of the lower pipe section is elliptical
  • the center of the lower pipe section is the origin
  • the long and short axes are the horizontal and vertical axes
  • the geometric function of the lower pipe section is:
  • h s is recorded as the distance between the powder focus and the bottom of the nozzle in the vertical direction
  • R s is the distance between the powder self-cleaning filter and the nozzle axis in the horizontal direction.
  • the partition-type housing includes an inner sleeve, an outer sleeve and a cooling sleeve;
  • the inner sleeve is nested in the outer sleeve and fixed at the upper end by a cover plate; the cover plate, the inner sleeve and the outer sleeve are enclosed to form a partition a;
  • the partition a includes an upper annular partition and a plurality of powder flow channels below which are uniformly distributed in the circumferential direction of the nozzle body, and each powder flow channel extends along the axial direction of the nozzle body;
  • the upper end of the annular partition is connected with more than two powder inlets provided on the cover plate, and the lower end is connected with the upper end of the powder channel, and the lower end of the powder channel is arranged through the lower end of the nozzle body; the inner sleeve is close to the annular partition.
  • the said protective gas inlet is set at the position of ;
  • the cooling jacket is sleeved on the periphery of the outer jacket, and a partition b is formed between the cooling jacket and the outer wall of the outer jacket.
  • the number of powder inlets is 2-8, and the included angle between the powder inlets and the horizontal plane is 10-90°.
  • the upper end of the overall shape of the inner sleeve is cylindrical, the lower end is tightened to form a truncated cone, and the hollow portion of the inner sleeve is truncated; the top of the inner sleeve is processed with an inwardly indented annular step, which is common with the outer sleeve.
  • the annular partition is defined and formed; a plurality of straight rectangular cross-section passages are arranged under the annular step and extend to the bottom end of the inner sleeve; the track of each rectangular cross-section passage is coplanar with the axis of the inner sleeve in space; At the annular step, a trumpet-shaped gap, which is large at the top and small at the bottom, connects the annular step with the rectangular section channel; the inner wall of the outer casing covers the outside of the rectangular section channel to promote the closure between each rectangular section channel and the inner wall of the outer casing.
  • a plurality of powder channels are formed independently of each other, and the powder and protective gas can smoothly enter the rectangular-section channel through the gap.
  • the upper end surface of the outer sleeve is provided with a flange plate that can be assembled with the cover plate, and the part close to the lower end surface can form a partition b with the cooling sleeve;
  • the main body of the cooling jacket is in the shape of a round tube, the inner diameter is matched with the lower half of the outer jacket, and can be fitted on the lower end of the outer jacket; the outer middle of the cooling jacket has a raised ring, and the cooling jacket has two adjacent holes, which are connected to the cooling water of import and export.
  • the number of powder collecting tubes is 2-8.
  • the upper pipe section of the powder collecting pipe is fixed on the outside of the nozzle body by fasteners; wherein, the fasteners include two, one is an annular clamping device, and the other is a pin fastener; the upper pipe section passes through
  • the annular clamping device is fixed with the outer side of the cooling sleeve, and is connected and fixed with the pin grooves arranged through the upper end surfaces of the inner and outer sleeves through the pin fasteners.
  • the present invention has the following beneficial effects:
  • the main part of the nozzle has a cylindrical design as a whole, which is beneficial to the assembly of various clamping equipment and the powder self-cleaning filter on the main body of the powder nozzle.
  • the walls equidistant from the axis are retained, which increases the degree of freedom of the powder self-cleaning filter nozzle in the axial direction, so that it can retract back after the lower end collides with the wall surface, with a certain degree of freedom. self-protection function.
  • the absorption of the nearby airflow by the powder self-purifying filter is consistent with the movement trajectory of the rear end of the transport gas, that is, after the powder transport task is completed, and does not affect the convergence of the transport gas on the powder.
  • FIG. 1 is a schematic three-dimensional structure diagram of the inner wall additive manufacturing coaxial powder feeding nozzle with self-cleaning function according to the present invention.
  • FIG. 2 is a partial cutaway schematic view of the powder nozzle portion of the coaxial powder feeding nozzle shown in FIG. 1 .
  • Figure 3a is a top view of the inner sleeve in Figure 2;
  • Figure 3b is an A-A sectional view of the inner sleeve in Figure 3a;
  • Figure 3c is a side view of Figure 3b;
  • Figure 3d is a three-dimensional structural view of the inner sleeve in Figure 2;
  • FIG. 4 is a perspective structural view of the walls of each watershed in FIG. 2 .
  • FIG. 5 is a cross-sectional view of the coaxial powder feeding nozzle shown in FIG. 1 .
  • Figure 6 is the simulation cloud diagram of the flow field trace during the powder feeding process of the coaxial nozzle.
  • Inner sleeve In the figure: 1. Inner sleeve; 2. Outer sleeve; 3. Cooling sleeve; 4. Cover plate; 5. Powder self-cleaning filter; 6. Blessing device; 7. Pin; 8. Connector; 9. Inner sleeve Through hole of pipe; 10. Through hole of outer casing; 11. Inlet of protective gas of nozzle; 12. Circular step; 13. Groove; 14. Inner wall of outer casing; 15. Circular cavity; 16. Powder flow 17. Outer surface of lower end of outer casing; 18. Inner wall of cooling casing; 19. Watershed; 20. Holes on cooling casing; 21. Cooling liquid inlet; 22.
  • spatially relative terms such as “on”, “over”, “on the surface”, “above”, etc., may be used herein to describe what is shown in the figures.
  • spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “above” or “over” other devices or features would then be oriented “below” or “over” the other devices or features under other devices or constructions”.
  • the exemplary term “above” can encompass both an orientation of "above” and “below.”
  • the device can also be positioned in other different ways (rotated 90 degrees or at other orientations).
  • the invention discloses an inner wall additive manufacturing coaxial powder feeding nozzle with a self-cleaning function, comprising a nozzle body, wherein the nozzle body includes a partition-type shell, a powder flow area, a cooling liquid flow area and a protective gas conveying flow channel; the partition wall
  • the type shell has a partition wall a and a partition wall b; the partition wall b is located on the outside of the partition wall a, the powder flow area is set in the partition wall a, and the cooling liquid flow area is set in the partition wall b; the powder flow area is provided with a powder inlet, a protective gas inlet, and a cooling liquid
  • the watershed is provided with a cooling liquid inlet;
  • the outer side of the partition-type casing is provided with a powder self-cleaning filter; wherein:
  • the powder self-cleaning filter is allocated with a group of powder collection pipes on both sides of the partition shell in the axial direction; each group of powder collection pipes includes at least one powder collection pipe;
  • the powder collecting tube has a two-section structure, including an upper tube section arranged in a straight tube shape and a lower tube section arranged in a curved tube shape.
  • the connecting head can be connected with the powder collecting system, and the lower end of the lower pipe section is the residual powder inlet, which is arranged below the metal pipeline to be processed and is located at the axial outer side of the powder gathering point of the metal pipeline to be processed;
  • the residual powder inlet of each powder collecting pipe can promote the residual powder on the opposite side to roll down the wall of the metal pipe to be processed on the same side to the and converge at the front end of the residual powder inlet of the powder collection tube, the residual powder inlet of the powder collection tube can collect the residual powder at its front end under the suction force exerted by the powder collection system.
  • the inner sleeve is nested in the outer sleeve and fixed at the upper end by a cover plate; the cover plate, the inner sleeve and the outer sleeve are enclosed to form a partition a;
  • the partition a includes an upper annular partition and a plurality of powder flow channels below which are uniformly distributed in the circumferential direction of the nozzle body, and each powder flow channel extends along the axial direction of the nozzle body;
  • the upper end of the annular partition is connected with more than two powder inlets provided on the cover plate, and the lower end is connected with the upper end of the powder channel, and the lower end of the powder channel is arranged through the lower end of the nozzle body; the inner sleeve is close to the annular partition.
  • the said protective gas inlet is set at the position of ;
  • the cooling jacket is sleeved on the periphery of the outer jacket, and a partition b is formed between the cooling jacket and the outer wall of the outer jacket.
  • the overall shape of the inner sleeve is a "bullet shape" with the upper end of the cylinder and the lower end of the circular truncated cone. Rectangular cross-section channels, these channels are equally spaced on the outer wall of the inner casing; each channel has a trumpet-shaped gap where the upper and lower parts are connected to the annular step.
  • the cross-sectional shape of the outer sleeve is in the shape of a Chinese character "bean" as a whole, the inner wall of the outer sleeve is consistent in size with the outer wall of the inner sleeve, and can be fitted together after assembly. The inner sleeve and the outer sleeve together confine a flow area for the powder and shielding gas.
  • the fine metal powder particles can converge directly under the nozzle.
  • an annular step protruding outwards is arranged on the upper side of the light channel, and a light path protection mirror is placed on the step surface.
  • the cover plate is in the form of a two-stage disc-shaped step.
  • the lower half of the cover plate and the protective glass in the inner sleeve (or the annular step on which the protective glass is placed) have the same radius; the upper half of the cover plate and the upper flange disc of the outer casing have the same shape, and are marked with corresponding Four bolt holes for easy fixing.
  • the inner side of the cover plate is punched with an inclined hole, which is connected with the powder flow basin formed after the inner and outer casings are assembled, and is the powder inlet.
  • the laser passes through the central channel, passes through the protective mirror, focuses on the axis, and interacts with the powder focus for cladding.
  • the upper sides of the outer sleeve and the inner sleeve are provided with positioning pin holes, which can be positioned relative to each other through pins.
  • a through hole shielding gas inlet
  • the two through holes are positioned by pins to ensure that the axes of the two through holes are coincident, forming a central
  • the optical channel passes through the side wall and leads to the "light path protective gas inlet" on the outside, which can provide the protective gas to protect the optical path part of the nozzle for the central optical channel, and prevent the protective mirror surface from being stained during the processing process. Bullet powder particles.
  • a section of circular pipe Below the flange disc at the top of the outer casing is a section of circular pipe, the outer diameter of which is the same as that of the cooling casing.
  • the lower part of the circular tube is a one-stage indented annular step, and the outer diameter of the annular step matches the inner diameter of the cooling jacket.
  • Below the annular step is a hollow truncated (funnel-shaped) thin wall that matches the shape of the inner casing, and a disc extends outward from the bottom end, the radius of which matches the inner diameter of the cooling casing.
  • the cooling jacket is fitted on the outer side of the lower half of the outer jacket, and under the joint restraint of the cooling jacket and the outer jacket, an annular space (partition b) is formed for the cooling liquid to flow and circulate in this space.
  • the sprinkler head is cooled.
  • a ring is raised in the middle of the cooling jacket.
  • a plane tangent to the main pipe (both sides of the nozzle) is machined to prevent the interference between the powder self-cleaning filter and the cooling jacket, which facilitates the powder self-cleaning.
  • There are two planes for the placement of the filter the inlet and outlet of the coolant are arranged on the same side of the nozzle (the side opposite to the feeding direction), and the corresponding planes are also processed for the convenience of processing and installation of pipes.
  • the powder self-cleaning filter is fixed on both sides of the nozzle (perpendicular to the feeding direction of the nozzle) to collect the unused powder (residual powder particles) during processing.
  • the entire powder nozzle has two fixing devices for the powder self-cleaning filter.
  • the cooling jacket can help the positioning of the fixing device of the powder self-cleaning filter in the direction of the nozzle axis.
  • the main body of the clamping part that is, the annular clamping device used to fix the powder self-cleaning filter has a circular shape, and its inner diameter forms a clearance fit with the inner diameter of the cooling jacket, which can be easily sleeved on the outside of the cooling jacket. This completes the positioning in the horizontal direction.
  • the outwardly protruding annular ring in the middle of the cooling jacket provides the fixing device with a supporting force corresponding to its gravity, which has reached the axial direction of the fixing device. the purpose of positioning.
  • annular clamping device annular clamping part
  • several annular clamps for holding the powder self-cleaning filter can be derived. By nesting the powder self-cleaning filter in the annular clamp, the horizontal plane is completed. position on.
  • d s represents the maximum particle size of the powder particles
  • ⁇ s is the density of the powder particle material
  • ⁇ is the density of the transport gas. According to the physical parameters of the powder and gas particles under different processing conditions, it is substituted into the formula (1) to obtain the powder in the processing process. The desired start-up speed of the particles.
  • the upper half of the powder self-cleaning filter is a straight tube, and the powder needs to move vertically upward in the straight tube. Therefore, the speed of the gas in this section of the pipeline also needs to meet certain requirements, and the size of this speed is called the suspension speed, denoted as u f . Due to the uniformity of the shape and physical parameters of the metal powder particles during the cladding process, the drag coefficient can also be defined as a fixed value for all powder particles.
  • the suspension velocity of powder particles during the cladding process can be expressed by formula (2):
  • the airflow velocity in the channel needs to reach 2 to 3.5 times the suspension velocity to ensure the normal transportation of powder particles in the vertical section of the pipeline. Therefore, the range of air velocity v r provided at the top inlet of the powder self-cleaning filter:
  • the uppermost end of the nozzle is integrated with n powder inlets, the radius of the powder inlet is defined as r, and the radius of the inlet of the powder self-cleaning filter is defined as R.
  • the radius R of the inlet of the powder self-cleaning filter can be defined as:
  • the collection inlet position of the powder self-cleaning filter can be accurately calculated according to the surrounding airflow velocity.
  • the inlet airflow In order for the inlet airflow to have a starting effect on the powder particles, it is necessary to ensure that the airflow velocity acting on the powder particles is 1.5 times the starting speed. Therefore, the distance h of the inlet from the bottom of the pipe can be calculated by the following inequality:
  • the upper side extensions of the inner and outer sleeves are provided with locating pin holes for locating the nozzle protective gas through holes on the inner and outer sleeves.
  • the positioning pin hole can also be used to assist the positioning of the upper part of the powder self-cleaning filter: at the other end of the positioning pin, a fixing ring for fixing the powder self-cleaning filter is processed, and the powder self-cleaning filter is sleeved on the fixing ring middle.
  • the fixing ring here also limits the degree of freedom of the powder self-cleaning filter in the horizontal direction. Under the combined action of the two, the positioning system of the powder self-cleaning filter can be Has better stability.
  • the top of the powder self-cleaning filter is connected with the back-end powder collecting system through a connector.
  • the connector is tightly sheathed on the top of the powder self-cleaning filter.
  • the fixed ring provides upward support to the connector, so that the entire powder self-cleaning filter can be collected.
  • the position in the axial direction is fixed.
  • the lower part of the powder self-cleaning filter is the lower pipe section, which is arranged in a curved tube shape, and the end is the residual powder inlet. After the powder particles interact with the laser, the transport gas and the unused residual powder enter the powder collection system.
  • the lower part of the powder self-cleaning filter is a curved pipe, and the projection on the horizontal plane of the pipe (the axial direction of the nozzle) from the bottom end of the nozzle to the next length does not coincide with the projection of the laser nozzle device itself on the horizontal plane (so the powder is self-cleaning).
  • the filter is translated upward along the axis direction, and the collecting pipe and the nozzle will not interfere with each other in this distance).
  • the distance between the powder focus and the nozzle bottom in the vertical direction is h s
  • the distance between the powder self-cleaning filter and the nozzle axis in the horizontal direction is constant R s .
  • the powder self-cleaning filter is observed in the side view, and the trajectory of the elbow part is a straight line. Therefore, the lower half of the elbow of the powder self-cleaning filter is elliptical, its center is the origin, its long and short axes are the horizontal and vertical axes, and its geometric function is:
  • the transporting shielding gas carries powder particles to help the metal powder particles to converge and interact with the laser.
  • the shielding gas clads the wall along the metal pipe and flows horizontally to both sides of the steel pipe axially.
  • the residual powder particles in the cladding process (powder that failed to adhere to the surface of the metal pipe) were ejected in all directions after colliding with the metal pipe substrate.
  • the nozzle Under the condition of inner wall processing, the nozzle is equivalent to processing in a sealed space. The residual powder will not be sprayed around like in an open space, but will gather at the bottom end of the processed metal pipe due to gravity and the constraints of the pipe wall.
  • the inlet of the powder self-cleaning filter is arranged at the bottom of the processed metal pipe, at a certain distance from the powder focus.
  • the powder self-cleaning filter port at the front end of the nozzle (based on the cladding feed direction) is oriented in the same direction as the linear velocity of the pipe wall (preferred), and the rear collection nozzle is oriented opposite to the linear velocity direction of the pipe wall.
  • the powder collection system provides the nozzle with a suction to the surrounding gas and powder. According to the orientation of the powder at the front end of the nozzle from the inlet of the filter, along the processing feed direction, the inner space of the metal tube can be divided into two equal left and right through the axial vertical section (the symmetrical plane of the metal tube axis perpendicular to the ground). area.
  • the residual powder splashes to the pipe wall of the metal on both sides of the section, and the powder flows from the side opposite to the inlet of the net filter, and the wall surface rolls upward relative to the ground, giving the residual particles a side upward and outward from the axis of the pipe.
  • the particles will roll down the wall to the bottom of the metal tube.
  • the residual particles on the side of the splash will roll down to the position where the bottom of the metal tube deviates from the symmetry plane and is close to the side, which is just in front of the inlet of the powder self-cleaning filter.
  • the powder at the front end of the nozzle comes from the wall surface on the opposite side of the net filter, giving the powder particles splashing on the wall surface a diagonal downward (biased to the inside of the axis) frictional force. Under the action of gravity and friction, the residual powder will cross the above-mentioned symmetrical plane of the metal pipe and converge to the bottom of the pipe space on the other side. These powders also gather to the front end of the inlet of the powder self-cleaning filter.
  • the rear end of the powder collection system provides a suitable airflow velocity from the inlet to the inner flow area of the collection tube, so that the surrounding gas carries the residual powder into the powder collection system and completes self-cleaning.
  • the transport gas contacts the wall under the constraint of the inner wall, because its viscosity is small, it will not rotate with the pipe, but will move from the powder convergence point to the axial two sides of the metal pipe against the bottom of the flow area in the pipe.
  • the inlet of the powder self-cleaning filter is located at a certain distance from the two axial sides of the metal tube at the powder convergence point.
  • a large amount of used transport protective gas passes through the inlet of the collection pipe, which meets the conditions for carrying residual powder into the collection system. Therefore, the unused residual powder can be collected without affecting the powder convergence during the operation of the powder nozzle, and the self-cleaning effect in the processing process can be obtained.
  • Inconel 718 is used as the cladding material on the inner wall of the metal tube
  • the protective transport gas is argon
  • the particle size distribution of the powder used is between 30 and 100 ⁇ m.
  • the powder nozzle part includes an inner sleeve 1 , an outer sleeve 2 and a cooling sleeve 3 .
  • the inner sleeve 1 is nested in the outer sleeve 2
  • the cooling sleeve 3 is fitted at the lower end of the outer sleeve 2 .
  • annular step 12 recessed inwardly on the outer side wall of the upper end of the inner sleeve 1, and along the conical wall surface on the lower side of the annular step 12, there are 12 inwardly opening
  • the concave straight grooves 13 are on the same plane as the axis of the inner sleeve 1 and are evenly distributed along the periphery of the inner sleeve 1 .
  • the outer sleeve 2 is fitted on the outer side of the inner sleeve 1 , and the inner wall 14 together with the groove 13 and the annular step 12 limits the movement area of the powder particles inside the nozzle. As shown in FIG.
  • the flow area of the powder flow includes the annular cavity 15 and the powder flow channel 16, which are connected to each other.
  • the transport shielding gas carries the powder particles into the flow area through the powder inlet 26, and first enters the annular cavity In the cavity 15, after performing a certain homogenization, the powder passes through the flow channel 16 and then converges.
  • the radius of the powder inlet is 2 mm
  • the unused utilization rate of the powder is 0.4
  • the radius of the powder from the inlet of the net filter is 2.5 mm.
  • a pin groove 25 is formed on the top of the inner sleeve 1 and the outer sleeve 2.
  • the pin fixing device 7 is installed in the pin groove 25 to position the inner and outer sleeves.
  • Nozzle shielding gas inlet 11 The nozzle shielding gas inlet communicates with the cavity 29 in the inner sleeve 1, i.e. the shielding gas field.
  • the cooling jacket is a hollow cylindrical shape as a whole, with an annular protrusion in the middle. On the raised ring, two adjacent planes are machined, and two holes 20 are punched on the plane.
  • the cooling jacket 3 is matched with The lower end of the outer sleeve 2 , the outer surface 17 of the lower end of the outer sleeve and the inner wall 18 of the cooling sleeve together form a wall surface that restricts the cooling fluid flow area 19 .
  • the cooling liquid enters the flow area 19 from the cooling liquid inlet 21, and then flows out from the cooling liquid outlet 22.
  • the cooling liquid takes away the heat received by the radiation at the bottom of the outer casing 3 in the flow area 19, so as to ensure that the plastic material at the powder inlet 26 is in the working state.
  • the pipes can be at the appropriate annular temperature.
  • the upper surface 23 protruding outward from the middle of the cooling jacket 3 provides the positioning and support of the nozzle in the axial direction for the holding device 6 of the powder self-cleaning filter.
  • the nozzle has two powder self-cleaning filters 5 , which are fixed on the left and right sides by a holding device 6 .
  • the main body of the holding device 6 is in a semicircle, and its inner diameter is the same as the outer diameter of the main part of the cooling jacket 3, and the components of the two holding devices are installed on the outside of the cooling jacket 3 oppositely. Small bolts are used for connection, so that the holding device 6 is fitted on the periphery of the cooling jacket 3 .
  • the holding device 6 With the cooperation of the annular surface 23 on the cooling jacket, the holding device 6 is fixed relative to the powder nozzle. On both sides of the holding device, there are two other small circular openings, the inner diameter is the same as the outer diameter of the powder self-cleaning filter 5, and the powder self-cleaning filter 5 can just be installed therein.
  • the tail end of the pin fixing device 7 is fixed in the pin groove 25, and the upper end is pressed by the cover plate 4 to ensure that it is fixed in the axial direction.
  • the front end of the pin fixing device 7 has an arc-shaped shelf with an opening outward, and the inner diameter is the same as the outer diameter of the powder self-cleaning filter 5.
  • the powder self-cleaning filter 5 has been positioned to increase its stability.
  • the connector 8 is firmly wrapped on the top of the powder self-cleaning filter 5, and the upward supporting force of the pin fixing device 7 is transmitted to the powder self-cleaning filter 5.
  • the powder self-cleaning filter 5 is also fixed in the axial direction relative to the powder spraying head.
  • the inner side of the inner sleeve 1 is processed with a circular step on which the protective glass 31 is placed. After the protective glass 31 is placed on the annular step, the space in the nozzle is divided into two sides, one side is the laser channel 30 , and the other side is the nozzle protective airflow area 29 .
  • the laser light comes from the channel 30, passes through the protective glass 31, and after the protective gas stream 29, is focused under the nozzle to interact with the powder.
  • the lower half of the powder self-cleaning filter 5 is an elbow, and the bottom end of the elbow has an air inlet 26, from which the reacted transport gas and unreacted powder enter the powder collection system 32.
  • the projection of the powder from the curved tube on the lower side of the filter 5 and the pipeline from the bottom end of the nozzle to the next length on the horizontal plane does not coincide with the projection of the laser nozzle device itself on the horizontal plane.
  • the movement trajectory of the powder flow during the processing is described; after the nozzle shielding gas carries the powder particles to converge and interact with the laser, due to the limitation of the pipe wall, the gas will clad the wall along the metal pipe, The horizontal flow flows to both sides of the steel tube axially.
  • the powder particles that are not used in the cladding process that is, the powder that cannot adhere to the surface of the metal pipe, will be ejected in all directions. Due to the radial constraints of the metal pipe, the powder will gather at the bottom of the metal pipe.
  • the inlet of the elbow is set at a certain distance from the powder focus.
  • the powder at the front end of the nozzle is directed towards the direction of the line speed of the metal pipe wall, and the collection nozzle at the rear end faces the line of the metal pipe.
  • the powder collection system provides the nozzle with a suction to the surrounding gas and powder.
  • the powder splashed at the front end is brought to the nozzle of the powder self-cleaning filter by the rotating metal tube. Because of the suction of the nozzle, it enters the powder collection system together with the surrounding gas.
  • the density of Inconel 718 is 8240kg/m3; when the room temperature of argon is 20°C, its density is 1.7837kg/m3; the maximum powder particle radius is 50 ⁇ m.
  • the starting speed of the powder is 1.17m/s, and the suspension speed is 2.62m/s. Therefore, the air velocity that needs to be provided at the top of the powder self-cleaning filter is between 5.24 and 9.2 m/s.
  • the air velocity added to the top inlet of the powder self-cleaning filter is set to be 7m/s. Therefore, the distance from the residual powder inlet of the powder from the end of the cleaning filter to the bottom surface of the cladding pipe should be less than 1.5mm. In order to ensure the safety during processing, the distance between the bottom end of the inlet and the wall should be kept 0.5mm.
  • the self-cleaning nozzle performs well in the processing process, and more than 90% of the powder in the residual powder is collected by the powder self-cleaning filter, which ensures the quality of cladding during the process of adding materials to the inner wall.

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Abstract

一种具有自净功能的内壁增材制造同轴送粉喷嘴，包括间壁式壳体、粉末流域、冷却液流域以及保护气输送流道；间壁式壳体的外侧设置有粉末自净收滤器（5）；粉末自净收滤器在间壁式壳体处于轴向的两侧各分配有一组粉末收集管；每组粉末收集管至少包括有一根粉末收集管；在粉末收集系统施加的抽吸力及残留粉末自身重力的共同作用下，每根粉末收集管的残留粉末入口均能够促使相对侧的残留粉末沿着同侧的待加工金属管道的壁面滚落至底部，并汇聚在所述粉末收集管的残留粉末入口的前端，粉末收集管即可收集处于自身前端的残留粉末，能够顺势对残余粉末进行收集，不影响粉流汇聚，且使加工过程中管道内保持清洁，提高熔覆质量。

Description

具有自净功能的内壁增材制造同轴送粉喷嘴 技术领域
本发明涉及一种具有自净功能的喷嘴及其系统，属于激光加工领域。
背景技术
自激光诞生以来，其越来越多地应用于先进制造技术之中，激光熔覆、激光钻孔、激光清洗、激光切割、激光焊接等等，都受到了广泛的关注。其精准、高效的加工特性使通过激光加工过程更节能更环保，激光加工已成为各国研究发展的重中之重。
在诸多与激光相关的加工技术中，激光熔覆是较为重要且运用交广的技术之一，激光熔覆，亦称激光包覆，的应用范围主要包括材料的表面改质、工件的修复再生以及三维快速成形。其通过在基底亦或是前一熔覆层上添加熔覆材料，通过施加高能激光束于其上，以融化基材与熔覆材料，二者结合，凝固形成添料熔覆层。加工过程中，相较于传统工艺，具有较低的输入热量与较小的热影响区，较小的变形程度与较细的组织，以广泛应用于航天、军事、工业、农业等领域中。
已有熔覆大致可分为预涂与同步送粉。预涂熔覆工序复杂，不易在复杂表面进行加工，稀释率难以控制。同步送粉又大致分为侧向送粉与同轴送粉两类。侧向送粉难以获得激光与粉末作用区较稳定的重合区，具有折角与弧线的路线难以加工。同轴喷在熔覆过程中，通过粉末与激光束的实时汇聚，提高了粉末的利用率，降低了稀释率，提高了熔覆过程中的精度与可控性，使可加工路线更加灵活多变，这为通过喷粉进行激光快速成形提供了条件。
在许多极端条件下，为延长关键金属构件的服役寿命，狭长金属管内亦需进行内壁防护层熔覆。通过金属管内表面改性，增加金属管内壁的耐磨性与抗腐蚀性。为增加金属管某些方向的强度和刚度，亦或是在金属管内制造某些特殊复杂结构，需在金属管内壁通过同轴喷嘴进行内壁增材制造，在已规划路径或区域内，进行特殊三维结构的内壁增材制造。
然而，同轴喷嘴最佳的加工位置为垂直于地面时与基体相距一个粉束焦距的正上方，此时喷嘴垂直向下进行内壁增材制造。而当喷头发生倾斜时，粉末易发生偏聚。在金属管内壁进行增材制造时，由于重力作用，在加工过程中未被利用的粉末，会顺着内壁两侧下滑至管底，如不及时清理或收集，将导致内壁增材制造过程成形区域粉末堆积并被其淹没，难以控制实际内壁熔覆粉末体积、熔池深度、稀释率等关键成形工艺参数，进而极大地降低了熔覆质量。而将喷头倾斜以避开管道底部进行加工，因粉末汇聚质量不佳，熔覆质量也难以得到保证。在加工过程中进行人工清理堆积粉末，由于激光热源作用间断时间长，高温金属冷却过程会发生明显的尺寸收缩效应，极大地降低了内壁复杂结构尺寸精度，也显著延长了制造周期。因此，在内壁增材制造过程中，设计具有自清洁功能的内壁喷头对高效和高质量内壁增材制造具有明显的经济和社会效益。
发明内容
本发明的主要目的在于针对目前内壁增材制造加工过程中，未被利用粉末堆积于金属管中，影响加工、难以清理的问题，提供一种在内壁增材环境条件下具有自清洁能力的同轴送粉喷嘴。
为实现上述的技术目的，本发明将采取如下的技术方案：
一种具有自净功能的内壁增材制造同轴送粉喷嘴，包括喷管本体，所述喷管本体包括间壁式壳体、粉末流域、冷却液流域以及保护气输送流道；间壁式壳体具有间壁a、间壁b；间壁b位于间壁a的外侧，粉末流域设置于间壁a内，而冷却液流域则设置于间壁b内；粉末流域设置有粉末入口、保护气入口，冷却液流域则设置有冷却液入口；所述间壁式壳体的外侧设置有粉末自净收滤器；
所述粉末自净收滤器在间壁式壳体处于轴向的两侧各分配有一组粉末收集管；每组粉末收集管至少包括有一根粉末收集管；
所述的粉末收集管为两段式结构，包括呈直管状设置的上管段以及呈弯管状设置的下管段，上管段与间壁式壳体外壁固定，且上管段的上端设置有连接头，连接头能够与粉末收集系统连接，下管段的下端为残留粉末入口，设置在待加工金属管道下方，并位于待加工金属管道粉末汇聚点的轴向外侧；
在粉末收集系统施加的抽吸力以及残留粉末自身重力的共同作用下，每根粉末收集管的残留粉末入口均能够促使相对侧的残留粉末沿着同侧的待加工金属管道的壁面滚落至底部，并汇聚在所述粉末收集管的残留粉末入口的前端，所述粉末收集管的残留粉末入口即可在粉末收集系统施加的抽吸力作用下，收集处于自身前端的残留粉末。
优选地，残留粉末入口相对于待加工金属管道底部的距离h满足：
Figure PCTCN2021125247-appb-000001
其中：n表示与粉末流域连通的粉末入口的数量；r为粉末入口的半径；η表示残留粉末颗粒占各粉末入口通入的粉末颗粒总量的体积分数；v r为上管段顶部所在位置处的气流速度；u q为粉末颗粒的启动速度；
Figure PCTCN2021125247-appb-000002
气流速度v r的范围：
Figure PCTCN2021125247-appb-000003
d s代表粉末颗粒的最大粒径，ρ s为粉末颗粒材料的密度，ρ为运输气体的密度。
优选地，残留粉末入口的半径R满足：
Figure PCTCN2021125247-appb-000004
式中：n表示与粉末流域连通的粉末入口的数量；r为粉末入口的半径；η表示残留粉末颗粒占各粉末入口通入的粉末颗粒总量的体积分数。
优选地，所述下管段的轨迹轮廓为椭圆形，以下管段的中心为原点、长短轴为横纵轴，下管段的几何函数为：
Figure PCTCN2021125247-appb-000005
h s记为粉末焦点与喷嘴底部竖直方向上的距离，R s为水平方向上粉末自净收滤器距离喷嘴轴线的距离。
优选地，所述间壁式壳体包括内套管、外套管以及冷却套管；
所述的内套管，嵌套于外套管内，并在上端通过盖板固定；盖板、内套管、外套管三者围合形成间壁a；
间壁a包括处于上方的环形间壁以及处于下方的若干条沿着喷管本体环向均布的粉末流道，各粉末流道均沿着喷管本体的轴向延伸；
环形间壁的上端与盖板上所设置的2个以上的粉末入口连通，下端则与粉末通道的上端连通，粉末通道的下端贯穿喷管本体的下端部设置；内套管在紧靠着环形间壁的位置处设置所述的保护气入口；
所述的冷却套管，套配在外套管的外围，并与外套管的外壁之间形成间壁b。
优选地，粉末入口的数量为2～8个，粉末入口与水平面之间的夹角呈10～90°。
优选地，内套管整体形状的上端呈圆柱形，下端收紧呈圆台形，内套管中空部分呈圆台形；内套管顶端加工有向内缩进的圆环形台阶，与外套管共同限定形成所述的环形间壁；圆环形台阶下方设置有若干条笔直的矩形截面通道延伸至内套管底端；各矩形截面通道的轨迹在空间上与内套管的轴线共面；在靠近圆环形台阶处，上大下小呈喇叭形的豁口将圆环形台阶与矩形截面通道相连；外套管的内壁覆盖在矩形截面通道的外侧以促使各矩形截面通道与外套管内壁之间闭合形成所述的若干条相互独立设置的粉末通道，粉末与保护气能够顺利地通过豁口进入到矩形截面通道中。
优选地，外套管上端面设置有能够与盖板配装的法兰盘，紧靠着下端面的部分，能够与冷却套管形成间壁b；
冷却套管主体呈圆管状，内径与外套下半部分配合，能够套配在外套管下端；冷却套管外侧中部有凸起的圆环，冷区套管开有相邻两孔，接冷却水的进出口。
优选地，粉末收集管的数量为2-8个。
优选地，粉末收集管的上管段通过紧固件固定在喷嘴本体的外侧；其中，紧固件包括两个，一个为圆环形夹持装置，另一个则为销钉固紧件；上管段通过圆环形夹持装置与冷却套管的外侧固定，并通过销钉固紧件与贯穿内、外套管上端面设置的销钉槽连接固定。
根据上述的技术方案，相对于现有技术，本发明具有如下的有益效果：
1、解决了传统内壁增材过程中未利用且难以清理粉末淤积等问题，有效改善了内壁增材制造加工环境并保证了有效加工区域，为内壁增材环境下的粉末喷嘴增加了自净的能力，使得未利用的粉末能够通过本发明中的粉末收集系统进行快速高效收集，保证良好的加工环境。
2、喷嘴主体部分，整体呈圆柱形的设计，有利于各种装夹设备以及粉末自净收滤器在粉末喷嘴主体上的装配。另外，在喷嘴主体的两侧，保留了与轴线等距的壁身，增加了粉末自净收滤器喷头轴向上的自由度，使其在下端与壁面碰撞后，能向回缩进，具备一定的自我保护功能。
3、粉末自净收滤器对附近气流的吸收，与运输气后端运动轨迹，即完成粉末运输 任务后，相吻合，并不影响运输气对于粉末的汇聚作用。
附图说明
图1是本发明所述的内壁增材制造具有自净功能同轴送粉喷嘴的立体结构示意图。
图2是图1所述同轴送粉喷嘴的粉末喷嘴部分的局部剖开示意图。
图3a是图2中内套管的俯视图；
图3b是图3a中内套管的A-A剖视图；
图3c是图3b的侧视图；
图3d是图2中内套管的立体结构图；
图4是图2中各流域壁面的立体结构图。
图5是图1所述同轴送粉喷嘴的剖视图。
图6是同轴喷嘴送粉过程中流场迹线的仿真云图。
图中：1、内套管；2、外套管；3、冷却套管；4、盖板；5、粉末自净收滤器；6、加持装置；7、销钉；8、连接头；9、内套管的通孔；10、外套管的通孔；11、喷嘴保护气入口；12、圆环形台阶；13、沟槽；14、外套管内壁；15、圆环形空腔；16、粉末流道；17、外套管下端外表面；18、冷却套管的内壁；19、流域；20、冷却套管上孔洞；21、冷却液入口；22、冷却液出口；23、冷却套管外凸部的上表面；24、圆环形台阶；25、销钉槽；26、粉末入口；27、粉末收集管的残留粉末入口；28、固定孔；29、内套管的空腔；30、激光通道；31、保护玻璃；32、粉末收集管的上管段。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。以下对至少一个示例性实施例的描述实际上仅仅是说明性的，决不作为对本发明及其应用或使用的任何限制。基于本发明中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。除非另外具体说明，否则在这些实施例中阐述的部件和步骤的相对布置、表达式和数值不限制本发明的范围。同时，应当明白，为了便于描述，附图中所示出的各个部分的尺寸并不是按照实际的比例关系绘制的。对于相关领域普通技术人员已知的技术、方法和设备可能不作详细讨论，但在适当情况下，所述技术、方法和设备应当被视为授权说明书的一部分。在这里示出和讨论的所有示例中，任何具体值应被解释为仅仅是示例性的，而不是作为限制。因此，示例性实施例的其它示例可以具有不同的值。
为了便于描述，在这里可以使用空间相对术语，如“在……之上”、“在……上方”、“在……上表面”、“上面的”等，用来描述如在图中所示的一个器件或特征与其他器件或特征的空间位置关系。应当理解的是，空间相对术语旨在包含除了器件在图中所描述的方位之外的在使用或操作中的不同方位。例如，如果附图中的器件被倒置，则描述为“在其他器件或构造上方”或“在其他器件或构造之上”的器件之后将被定位为“在其他器件或构造下方”或“在其他器件或构造之下”。因而，示例性术语“在……上方”可以包括“在……上方”和“在……下方”两种方位。该器件也可以其他不同方式定位(旋转90度或处于其他方位)。
本发明公开了一种具有自净功能的内壁增材制造同轴送粉喷嘴，包括喷管本体，所述喷管本体包括间壁式壳体、粉末流域、冷却液流域以及保护气输送流道；间壁式壳体具有间壁a、间壁b；间壁b位于间壁a的外侧，粉末流域设置于间壁a内，而冷却液流域则设置于间壁b内；粉末流域设置有粉末入口、保护气入口，冷却液流域则设置有冷却液入口；所述间壁式壳体的外侧设置有粉末自净收滤器；其中：
所述粉末自净收滤器在间壁式壳体处于轴向的两侧各分配有一组粉末收集管；每组粉末收集管至少包括有一根粉末收集管；
所述的粉末收集管为两段式结构，包括呈直管状设置的上管段以及呈弯管状设置的下管段，上管段与间壁式壳体外壁固定，且上管段的上端设置有连接头，连接头能够与粉末收集系统连接，下管段的下端为残留粉末入口，设置在待加工金属管道下方，并位于待加工金属管道粉末汇聚点的轴向外侧；
在粉末收集系统施加的抽吸力以及残留粉末自身重力的共同作用下，每根粉末收集管的残留粉末入口均能够促使相对侧的残留粉末沿着同侧的待加工金属管道的壁面滚落至底部，并汇聚在所述粉末收集管的残留粉末入口的前端，所述粉末收集管的残留粉末入口即可在粉末收集系统施加的抽吸力作用下，收集处于自身前端的残留粉末。
所述的内套管，嵌套于外套管内，并在上端通过盖板固定；盖板、内套管、外套管三者围合形成间壁a；
间壁a包括处于上方的环形间壁以及处于下方的若干条沿着喷管本体环向均布的粉末流道，各粉末流道均沿着喷管本体的轴向延伸；
环形间壁的上端与盖板上所设置的2个以上的粉末入口连通，下端则与粉末通道的上端连通，粉末通道的下端贯穿喷管本体的下端部设置；内套管在紧靠着环形间壁的位置处设置所述的保护气入口；
所述的冷却套管，套配在外套管的外围，并与外套管的外壁之间形成间壁b。
所述内套管整体形状呈上端为圆柱下端为圆台的“子弹形”，内套管顶端有一向内侧缩进的圆环形台阶，内套管外侧有与空间上与轴线处于同一平面上的矩形截面通道，这些通道在内套管外壁等距分布；每个通道与圆环台阶连接处，都有一个上大下小的喇叭形豁口。外套管截面形状整体呈汉字“豆”形，外套管内壁与内套管外壁尺寸上吻合，装配后能够贴合在一起。内套管与外套管共同为粉末与保护气限制一个流域，沿着各个流道，细金属粉末颗粒能够在喷嘴正下方进行汇聚。内套管内部有一个圆台形的光通道，在光通道上侧有一个向外突出的环形台阶，台阶面上放置光路保护镜。
喷嘴上方是盖板，盖板呈上大下小两级圆盘形台阶。在盖板下半部分与内套中的保护玻璃(或放置保护玻璃的环形台阶)半径相等；盖板上半部分与外套管上端法兰圆盘形状全等，并且相对应地打有对应的四个螺栓孔，用以方便固定。盖板内侧打有斜孔，与内、外套管装配后形成的粉流流域相连通，是为粉末入口。激光自中心通道而过，穿过保护镜，聚焦于轴线上，与粉末焦点相作用，进行熔覆。
外套管与内套管的上侧，开有定位销孔，可以通过销钉对其相对位置进行定位。在内、外套管装配后，在内部无粉末流域的壁面处设计一个通孔(保护气入口)，嵌套安装后，通过销钉定位，保证该两通孔的轴线相重合，共同组成一个由中心光通道穿过侧壁通至外侧的“光路保护气入口”，如此可为中心光通道提供保护喷嘴光路部分的保护气，防止在加 工过程中保护镜面沾上熔覆过程中未被利用而回弹的粉末颗粒。
外套管顶端法兰圆盘下，是一段圆管部分，外径与冷却套管的外径相同。圆管部分往下是一级内缩的环形台阶，此环形台阶的外径与冷却套管的内径相配合。环形台阶下是一与内套管形状相配合的中空圆台形(漏斗形)薄壁，至其底端向外扩展出一个圆盘，其半径与冷却套管内径尺寸配合。这样，冷却套管配合安装在外套管下半部分的外侧，冷却套管与外套管共同限制作用下，形成了一个环形的空间(间壁b)，供冷却液在此空间中进行流动循环，对喷头进行冷却作业。冷却套管中部凸起一段圆环，在此段圆环上，加工出与主体圆管相切的平面(喷头两侧)，防止粉末自净收滤器与冷却套管产生干涉，方便了粉末自净收滤器的安置，加工有两平面；冷却液的进出口安排在喷头的同一侧(与进给方向相反的方向的那一侧)，为方便加工与管道的安装，同样加工出相应的平面。
粉末自净收滤器固定在喷头两侧(垂直于喷头进给方向)，对加工过程中未被利用的粉末(残留粉末颗粒)进行收集。整个粉末喷头对粉末自净收滤器有两处固定装置。冷却套管中能帮助粉末自净收滤器固定装置在喷头轴线方向上的定位。用以固定粉末自净收滤器的装夹部件(即圆环形夹持装置)主体呈圆环形，其内径与冷却套管的内径形成间隙配合，能够轻松地环套在冷却套管的外，由此水平方向上便完成了定位。与此同时，冷却套管中间向外凸起的圆环，其圆环面与固定装置接触的地方，为固定装置提供了一个与其重力相对应的支撑力，已达到对固定装置在轴向上进行定位的目的。环形夹持装置(圆环形装夹部件)的两侧，可以衍生出若干用以加持粉末自净收滤器的圆环形夹具，通过将粉末自净收滤器嵌套在圆环形夹具中，完成水平面上的定位。
根据粉末运动规律，气流作用在粉末上并使粉末进行运动需要一个合适的气流速度。该气体流速将由粉末形状、特征尺寸、材料属性以及与界面的摩擦系数等因素共同决定，且该速度被定义为启动速度，我们在此记为u q。由于粉末颗粒的球形度较好，且特征尺寸分布较为集中，故类似阻力系数、摩擦系数等参数，大部分材料的熔覆过程中，对于所有的颗粒而言，是一个固定值。材料密度、运输气体密度以及颗粒最大粒径等材料属性会根据成形加工要求和环境条件的改变而发生函数变化。因此，熔覆过程中粉末颗粒的启动速度可由等式(1)表示：
Figure PCTCN2021125247-appb-000006
其中d s代表粉末颗粒的最大粒径，ρ s为粉末颗粒材料的密度，ρ为运输气体的密度，根据不同加工条件下粉末与气体颗粒物性参数代入式(1)，获得该加工过程中粉末颗粒所需要的启动速度。
粉末自净收集虑器上半结构为直管，粉末需在直管中竖直向上运动。因此，在此段管道中气体的速度同样需要满足一定的要求，该速度的大小称之为悬浮速度，记为u f。由于熔覆过程中金属粉末颗粒在形状与物性参数表现为均一性，对于所有粉末颗粒而言，阻力系数同样可定义为固定值。熔覆过程中粉末颗粒的悬浮速度可由式(2)来表示：
Figure PCTCN2021125247-appb-000007
同样的，将不同加工条件下粉末与气体颗粒的d s、ρ s和ρ代入上式，求得该加工过程中粉末颗粒所需的悬浮速度。
通常，通道内的气流速度需达到悬浮速度的2～3.5倍，才能保证粉末颗粒在竖直段管道中的正常运输。因此，为粉末自净收集虑器顶端入口处提供的气流速度v r的范围：
Figure PCTCN2021125247-appb-000008
在熔覆过程中，对激光焦点进行调整后，反应过程中大部分粉末能与激光作用并实现沉积，而余下粉末，在此我们称之为残余粉末，占粉末总量的体积分数为η。在喷嘴的最上端集成有n个粉末入口，粉末入口半径定义为r，而粉末自净收集虑器入口半径定义为R。粉末自净收集虑器入口的半径R，可定义为：
Figure PCTCN2021125247-appb-000009
粉末自净收滤器的收集入口位置，可根据周边气流速度可进行精确计算。为使入口气流能对粉末颗粒有启动作用，需保证作用于粉末颗粒上的气流流速为启动速度的1.5倍。因此，入口距离管道底部的距离h可以由以下不等式进行计算：
Figure PCTCN2021125247-appb-000010
内外套管上侧边延处有用于定位内外套管上喷嘴保护气通孔的定位销孔。与此同时，定位销孔还可以用于辅助粉末自净收滤器上端部分进行定位：在定位销的另一端，加工出用于固定粉末自净收滤器的固定环，将粉末自净收滤器套在固定环中。与上述安装在冷却套管周围的固定装置一样，此处的固定环也对粉末自净收滤器水平方向上的自由度进行了限定，二者的共同作用下，能使粉末自净收滤器的定位系统具有较好的稳定性。粉末自净收滤器的顶端与后端粉末收集系统通过一个连接头进行连接，连接头紧紧外套在粉末自净收滤器顶部，固定环向连接头提供向上的支撑力，从而能够使整个粉末自净收滤器在轴向上的位置得以固定。
粉末自净收滤器的下半部分为下管段，呈弯管状设置，末端是残留粉末入口，粉末颗粒与激光作用后，运输气与未利用的残余粉末由此进入粉末收集系统。粉末自净收滤器下半部分是曲管，(喷嘴轴向)自喷头底端起往下一段长度的管道，在水平面上的投影不与激光喷嘴装置自身在水平面上的投影重合(因此将粉末自净收滤器延轴线方向向上平移，收集管与喷头在此段距离中相互间并不会产生干涉)。记粉末焦点与喷嘴底部竖直方向上的距离为h s，水平方向上粉末自净收滤器距离喷嘴轴线的距离恒为R s。在侧视图中对粉末自净收滤器进行观察，其弯管部分的轨迹为一条直线。因此，粉末自净收滤器的下半段弯管为椭圆形，以其中心为原点，其长短轴为横纵轴，其几何函数为：
Figure PCTCN2021125247-appb-000011
运输保护气携带粉末颗粒帮助金属粉末颗粒进行汇聚并且与激光进行作用后，在被加工金属管管壁的约束下，保护气沿着金属管道熔覆壁面，水平流向钢管轴向两边。而熔覆过程中的残余粉末颗粒(没能粘附到金属管道表面的粉末)在与金属管基体发生碰撞后，向各个方向弹出。内壁加工的条件下，喷头相当于在密封空间中进行加工，残余粉末并不会像在开放空间中那样向周围喷洒，而是因为重力以及管壁的约束，聚集在加工金属管的底端。粉末自净收滤器的入口设置在被加工金属管道底部、与粉末焦点相距一定距离处。喷嘴前端 粉末自净收滤器口(以熔覆进给方向为准)的朝向与管壁线速度的方向相同(优先选择)，而后端收集管口朝向相反于管壁的线速度方向。粉末收集系统为管口提供一个对周边气体与粉末的吸力。按照喷嘴前端粉末自净收滤器入口的朝向，沿着加工进给方，可以向将金属管内部空间通过轴向竖直截面(金属管轴向垂直于地面的对称面)划分为左右两个相等的区域。加工过程中，残余粉末飞溅至截面两侧金属的管壁，粉末自净收滤器入口正对的一侧，其壁面相对于地面向上滚动，给残余颗粒一个向侧上方、由管道的轴心向外的摩擦力，然而由于重力因素，颗粒会沿着壁面滚落至金属管底部。在重力与摩擦力的共同作用下，飞溅这一侧的残余颗粒会滚落到金属管底部偏离对称面而靠近本侧的位置，而此处正好处于粉末自净收滤器入口前方。而喷嘴前端粉末自净收滤器相反方向一侧的壁面，给予飞溅到其壁面上粉末颗粒一个斜向下(偏向轴线内侧)的摩擦力。残余粉末在重力与摩擦力的作用下，会越过上述的金属管道对称面，汇聚到另一侧管道空间的底部，这些粉末也一同聚集到了粉末自净收滤器入口的前端。粉末收集系统的后端提供一个大小合适的由入口流向收集管内部流域的气流速度，致使周围的气体携带残余粉末一并进入到粉末收集系统中，完成自清洁。
加工过程中，运输气体在内壁约束下接触壁面，因为自身粘度较小并不会随着管道一起转动，而是会贴着管道中流域底部自粉末汇聚点向金属管轴向两侧向运动。粉末自净收滤器入口，位于粉末汇聚点金属管轴向两侧一定距离处。运载保护器将粉末运送使其汇聚并与激光作用后，管壁限制的空间中运载保护器的运动迹线在粉末自净收滤器附近较为密集，垂直方向上速度梯度大，金属管竖直方向上下侧壁面附近的流速较快，流量较大，大量使用过的运输保护气经过收集管入口处，符合携带残余粉末进入收集系统的条件。因此，能够在不影响粉末喷嘴工作时粉末汇聚性的情况下，对未利用的残余粉末进行收集，获得在加工过程中的自净效果。
以下将结合一个具体实施例详细地说明本发明的技术方案。
此案例中在金属管内部壁面上进行Inconel 718作为熔覆材料，保护运输气为氩气，所使用的粉末粒径分布在30～100μm之间。
图1至图5示出了本实施例的具体结构。如图2所示，粉末喷嘴部分包括内套管1、外套管2和冷却套管3，内套管1嵌套在外套管2中，与此同时冷却套管3套配在外套管2下端。如图3a-d中所示，内套管1上端的外侧壁面上有一个向内侧凹陷的圆环形台阶12，在圆环形台阶12下侧沿着锥形壁面，开有12条向内凹陷的笔直沟槽13，沟槽13与内套管1轴线处于同一平面上，并且沿着内套管1外围均匀分布。外套管2套配于内套管1外侧，其内壁14与沟槽13及圆环形台阶12一同限制了一个喷头内部粉末颗粒运动的区域。如图4中所示，粉流的流域包含圆环形空腔15与粉末流道16，二者之间相互连通，运输保护气携带粉末粒子由粉末入口26进入流域，首先进入到圆环形空腔15中，在进行了一定的均匀化作用后，粉末通过流道16后汇聚。此处，粉末入口的半径为2mm，而粉末的未利用率为0.4，求得此处的粉末自净收滤器入口的半径为2.5mm。
内套管1与外套管2顶端上开有销钉槽25，内套管1与外套管2嵌套安装后，销钉固定装置7装卡在销钉槽25中，对内外套管进行定位。内套管外壁无凹槽13处，打有通孔9，与之相对的外套管壁则打有通孔10，两孔在销钉7的定位作用下，使得两孔的轴线相重合，一同组成喷嘴保护气入口11。喷嘴保护气入口连通至内套管1中的空腔29，也就是保护气流 域。
冷却套管整体为空心圆柱形，中间有圆环形凸起，在突起的圆环上，加工出两个相邻平面，并且在平面上打有两个孔洞20，冷却套管3套配于外套管2下端，外套管下端外表面17与冷却套管内壁18一同构成了限制冷却液流域19的壁面。冷却液由冷却液入口21进入流域19，而后自冷却液出口22流出，冷却液在流域19中带走外套管3底部因为辐射受到的热量，保证在处于工作状态时，粉末入口26处的塑料管道能够在适当的环形温度下。
冷却套管3中部向外突出的上表面23为粉末自净收滤器的加持装置6提供了喷嘴轴向上的定位与支撑。如图1所示，本例中喷嘴有两个粉末自净收滤器5，通过加持装置6固定在左右两侧。如图1中所示，加持装置6在此主体呈半圆，其内径与冷却套管3主题部分的外径相同，将两个加持装置的部件相对地安装在冷却套管3的外侧，通过较小的螺栓进行连接，便使得加持装置6套配在冷却套管3的外围。在冷却套管上的圆环面23的配合下，加持装置6相对于粉末喷嘴进行了固定。在加持装置的两侧，另外有两个圆形的小口子，内径与粉末自净收滤器5的外径相同，粉末自净收滤器5刚好能够安装在其中。销钉固定装置7尾端固定在销钉槽25中，上端由盖板4压住，确保其在轴向上固定。销钉固定装置7前端有一个优弧形的架子，开口向外，内径与粉末自净收滤器5的外径相同，对粉末自净收滤器5进行过定位，增加其稳定性。帮助定位粉末自净收滤器5轴向位置的是连接头8，连接头8牢固地包覆在粉末自净收滤器5的顶端，销钉固定装置7对其向上的支撑力传递至粉末自净收滤器5，使粉末自净收滤器5相对于粉末喷头在轴向上也得以固定。
内套管1的内侧，加工有一个放置保护玻璃31的圆环形台阶。保护玻璃31放置在这个圆环形台阶上以后，喷嘴内的空间分为两侧，一侧为激光通道30，另一侧为喷嘴保护气流域29。激光由通道30而来，穿过保护玻璃31，及保护气流域29后，聚焦于喷嘴下方与粉末间进行相互作用。
粉末自净收滤器5的下半部分为弯管，弯管底端有一个气流入口26，反应后的运输气与未反应粉末由此进入粉末收集系统32。粉末自净收滤器5下侧的曲管，从喷头底端起往下一段长度的管道，在水平面上的投影不与激光喷嘴装置自身在水平面上的投影重合。
如图6中所示，描述了在加工过程中粉流的运动轨迹；喷嘴保护气携带粉末颗粒进行汇聚并且与激光进行作用后，因为管壁的限制，气体会沿着金属管道熔覆壁面，水平流向钢管轴向两边。而熔覆过程中未利用到的粉末颗粒，也就是没能粘附到金属管道表面的粉末，会向各个方向弹出，由于金属管道在径向上的约束，粉末聚集在金属管底部。弯管的入口设置在距离粉末焦点一定距离处，熔覆进给方向上喷嘴前端粉末自净收滤器口朝向优先选择金属管壁线速度的方向同向，而后端的收集管口则朝向与金属管道线速度方向相反的方向。粉末收集系统为管口提供一个对周边气体与粉末的吸力。加工过程中，前端飞溅的粉末被旋转的金属管顺势带到粉末自净收滤器的管口，因为管口的吸力，随着周围的气体一并进入到粉末收集系统中。
Inconel 718的密度为8240kg/m3；氩气室温为20℃时，其密度为1.7837kg/m3；其中最大粉末颗粒半径为50μm。经过计算，粉末的启动速度为1.17m/s，而悬浮速度为2.62m/s。因此，在粉末自净收滤器顶端所需要提供的气流速度在5.24～9.2m/s之间。为了保证粉末在管道中的顺利运输，设置添加给粉末自净收滤器顶端入口的气流速度为7m/s。从而粉末自净收滤器末端残余粉末入口距离熔覆管道底面的距离应小于1.5mm，为保证加工过程中 的安全，入口底端与壁面间保持0.5mm的距离。
本实施例中，自净喷嘴在加工过程中表现出色，残余粉末中九成以上的粉末通过粉末自净收滤器得以收集，保证了内壁增材过程中的熔覆质量。
上述实施例为本发明较佳的实施方式,但本发明的实施方式并不受上述实施例的限制,其他的任何未背离本发明的精神实质与原理下所作的改变、修饰、替代、组合、简化,均应为等效的置换方式,都包含在本发明的保护范围之内。

Claims (10)

  1. 一种具有自净功能的内壁增材制造同轴送粉喷嘴，包括喷管本体，所述喷管本体包括间壁式壳体、粉末流域、冷却液流域以及保护气输送流道；间壁式壳体具有间壁a、间壁b；间壁b位于间壁a的外侧，粉末流域设置于间壁a内，而冷却液流域则设置于间壁b内；粉末流域设置有粉末入口、保护气入口，冷却液流域则设置有冷却液入口；其特征在于，所述间壁式壳体的外侧设置有粉末自净收滤器；
    所述粉末自净收滤器在间壁式壳体处于轴向的两侧各分配有一组粉末收集管；每组粉末收集管至少包括有一根粉末收集管；
    所述的粉末收集管为两段式结构，包括呈直管状设置的上管段以及呈弯管状设置的下管段，上管段与间壁式壳体外壁固定，且上管段的上端设置有连接头，连接头能够与粉末收集系统连接，下管段的下端为残留粉末入口，设置在待加工金属管道下方，并位于待加工金属管道粉末汇聚点的轴向外侧；
    在粉末收集系统施加的抽吸力以及残留粉末自身重力的共同作用下，每根粉末收集管的残留粉末入口均能够促使相对侧的残留粉末沿着同侧的待加工金属管道的壁面滚落至底部，并汇聚在所述粉末收集管的残留粉末入口的前端，所述粉末收集管的残留粉末入口即可在粉末收集系统施加的抽吸力作用下，收集处于自身前端的残留粉末。
  2. 根据权利要求1所述的具有自净功能的内壁增材制造同轴送粉喷嘴，其特征在于，残留粉末入口相对于待加工金属管道底部的距离h满足：
    Figure PCTCN2021125247-appb-100001
    其中：n表示与粉末流域连通的粉末入口的数量；r为粉末入口的半径；η表示残留粉末颗粒占各粉末入口通入的粉末颗粒总量的体积分数；v r为上管段顶部所在位置处的气流速度；u q为粉末颗粒的启动速度；
    Figure PCTCN2021125247-appb-100002
    气流速度v r的范围：
    Figure PCTCN2021125247-appb-100003
    d s代表粉末颗粒的最大粒径，ρ s为粉末颗粒材料的密度，ρ为运输气体的密度。
  3. 根据权利要求1所述的具有自净功能的内壁增材制造同轴送粉喷嘴，其特征在于，残留粉末入口的半径R满足：
    Figure PCTCN2021125247-appb-100004
    式中：n表示与粉末流域连通的粉末入口的数量；r为粉末入口的半径；η表示残留粉末颗粒占各粉末入口通入的粉末颗粒总量的体积分数。
  4. 根据权利要求1所述的具有自净功能的内壁增材制造同轴送粉喷嘴，其特征在于，所述下管段的轨迹轮廓为椭圆形，以下管段的中心为原点、长短轴为横纵轴，下管段的几何函数为：
    Figure PCTCN2021125247-appb-100005
    h s记为粉末焦点与喷嘴底部竖直方向上的距离，R s为水平方向上粉末自净收滤器距离喷嘴轴线的距离。
  5. 根据权利要求1所述的具有自净功能的内壁增材制造同轴送粉喷嘴，其特征在于，所述间壁式壳体包括内套管、外套管以及冷却套管；
    所述的内套管，嵌套于外套管内，并在上端通过盖板固定；盖板、内套管、外套管三者围合形成间壁a；
    间壁a包括处于上方的环形间壁以及处于下方的若干条沿着喷管本体环向均布的粉末流道，各粉末流道均沿着喷管本体的轴向延伸；
    环形间壁的上端与盖板上所设置的2个以上的粉末入口连通，下端则与粉末通道的上端连通，粉末通道的下端贯穿喷管本体的下端部设置；内套管在紧靠着环形间壁的位置处设置所述的保护气入口；
    所述的冷却套管，套配在外套管的外围，并与外套管的外壁之间形成间壁b。
  6. 根据权利要求5所述的具有自净功能的内壁增材制造同轴送粉喷嘴，其特征在于，粉末入口的数量为2～8个，粉末入口与水平面之间的夹角呈10～90°。
  7. 根据权利要求5所述的具有自净功能的内壁增材制造同轴送粉喷嘴，其特征在于，内套管整体形状的上端呈圆柱形，下端收紧呈圆台形，内套管中空部分呈圆台形；内套管顶端加工有向内缩进的圆环形台阶，与外套管共同限定形成所述的环形间壁；圆环形台阶下方设置有若干条笔直的矩形截面通道延伸至内套管底端；各矩形截面通道的轨迹在空间上与内套管的轴线共面；在靠近圆环形台阶处，上大下小呈喇叭形的豁口将圆环形台阶与矩形截面通道相连；外套管的内壁覆盖在矩形截面通道的外侧以促使各矩形截面通道与外套管内壁之间闭合形成所述的若干条相互独立设置的粉末通道；
    粉末与保护气能够顺利地通过豁口进入到矩形截面通道中。
  8. 根据权利要求5所述的具有自净功能的内壁增材制造同轴送粉喷嘴，其特征在于，外套管上端面设置有能够与盖板配装的法兰盘，紧靠着下端面的部分，能够与冷却套管形成间壁b；
    冷却套管主体呈圆管状，内径与外套下半部分配合，能够套配在外套管下端；冷却套管外侧中部有凸起的圆环，冷区套管开有相邻两孔，接冷却水的进出口。
  9. 根据权利要求5所述的具有自净功能的内壁增材制造同轴送粉喷嘴，其特征在于，粉末收集管的数量为2-8个。
  10. 根据权利要求5所述的具有自净功能的内壁增材制造同轴送粉喷嘴，其特征在于，粉末收集管的上管段通过紧固件固定在喷嘴本体的外侧；其中，紧固件包括两个，一个为圆环形夹持装置，另一个则为销钉固紧件；上管段通过圆环形夹持装置与冷却套管的外侧固定，并通过销钉固紧件与贯穿内、外套管上端面设置的销钉槽连接固定。
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