CN115814975A

CN115814975A - Cold spraying gun

Info

Publication number: CN115814975A
Application number: CN202211480293.9A
Authority: CN
Inventors: 乐咏琪; 李红军
Original assignee: Zhejiang Sci Tech University ZSTU
Current assignee: Zhejiang Sci Tech University ZSTU
Priority date: 2022-11-22
Filing date: 2022-11-22
Publication date: 2023-03-21

Abstract

A cold spray gun comprises a spray pipe and a powder barrel, wherein the spray pipe is provided with a gas inlet and a gas outlet, the powder barrel is sleeved on the periphery of the side wall of the spray pipe and extends along the first axial direction of the spray pipe, an annular powder cavity is formed between the inner peripheral wall of the powder barrel and the side wall of the spray pipe, and the end part of the powder barrel, close to the gas outlet, is provided with a powder outlet; along the gas flowing direction, the powder outlet is positioned at the downstream of the gas outlet of the spray pipe and is opposite to the gas outlet; the powder filter is characterized by further comprising a filter cylinder, wherein the filter cylinder is arranged between a powder outlet of the powder cylinder and a gas outlet of the spray pipe and extends along a first axial direction, a first end portion of the filter cylinder is opposite to and communicated with the gas outlet of the spray pipe, a second end portion of the filter cylinder is opposite to and communicated with the powder outlet of the powder cylinder, the cylinder wall of the filter cylinder is opposite to the powder cavity, and a plurality of first filter holes penetrating through the wall thickness are distributed at intervals, so that powder in the powder cavity can enter the filter cylinder through the first filter holes. Compared with the prior art, the invention can prevent a large amount of powder from flowing into the outlet of the spray pipe.

Description

Cold spraying gun

Technical Field

The invention belongs to the technical field of material surface spraying, and particularly relates to a cold spraying gun.

Background

Cold Spray is known collectively as Cold Gas Dynamic Spray (GCDS). The cold spraying system mainly comprises a high-pressure gas source, a spray gun system, a gas temperature control system, a powder feeding system, a gas regulating system and a powder recovery system. The cold spraying technology takes high-pressure gas (nitrogen, helium or compressed air) as a carrier, powder particles are accelerated to 300-1200 m/s through a Laval (Laval) spray pipe, the powder particles are impacted on the surface of a substrate at a high speed in a solid state, the powder particles are driven to generate heat insulation shearing instability through high-speed airflow to cause the plastic deformation of the powder, so that a coating is formed, and the formed coating has the advantages of high density, low porosity, no oxidation, maximized heat conductivity and electric conductivity and the like, so that the cold spraying technology is widely applied to the industries such as aerospace industry, automobile industry and the like.

The Laval nozzle used for cold spraying is also called as a supersonic speed nozzle, along the flowing direction of air flow, the inner diameter of the front half part of the Laval nozzle is gradually reduced to form a contraction section, the inner diameter of the rear half part of the Laval nozzle is gradually increased to form an expansion section, and a narrow throat is formed at the joint of the contraction section and the expansion section. The gas at the inlet flows into the front half of the nozzle under high pressure, passes through the narrow throat and escapes from the rear half. The structure can change the speed of the airflow due to the change of the spray cross section area, so that the airflow is accelerated from subsonic speed to sonic speed to supersonic speed. The powder particles in the gas flow under supersonic speed can deposit on the surface of the substrate to form a coating. However, at supersonic speed, when the air flow and the powder particles are sprayed out from the nozzle of the laval nozzle, the air flow and the powder particles are rapidly dispersed, so that the spraying precision is reduced.

Therefore, the utility model patent No. 201822205131.X discloses a high-speed laser spraying device (No. CN209722309U is announced to the grant) utility model patent No. 201822205131.X, including the laser cavity pipe, the nozzle, activity keeps off material circle and protection air cock, the left part of laser cavity pipe is connected with high-pressurepipe, the inner chamber right part threaded connection of laser cavity pipe has the nozzle, the inside powder pipe that send that is equipped with of lateral wall of adapter sleeve, the inside wall threaded connection of adapter sleeve has the protection air cock, be equipped with first annular class taper space between the lateral wall of activity fender material circle and nozzle, protection air cock and activity keep off and have second annular taper space between the material circle, the inside protection trachea that is equipped with of lateral wall of protection air cock, second annular taper space is linked together with the protection trachea, the inside wall right part of adapter sleeve is equipped with the draw-in groove, the joint has the jump ring in the draw-in groove. Therefore, the protective gas forms a circle of protective gas curtain outside the spraying movement path, and the spraying powder is effectively prevented from splashing. The size of the first annular conical or conical gap is adjusted by adjusting the tightness of the threads of the movable material blocking ring and the connecting sleeve, so that the flow of the spraying powder is controlled; the size of the second annular taper gap is adjusted by adjusting the tightness of the protective air nozzle, the movable material blocking ring and the threads of the connecting sleeve, so that the air pressure of the protective gas is controlled.

Above-mentioned utility model patent is interior to control spraying powder flow through adjusting movable material blocking ring, still has a large amount of powder granules and gushes into the spray tube export together, causes the powder granule to block up to influence the problem of the normal work of spray gun.

Disclosure of Invention

The first technical problem to be solved by the invention is to provide a cold spray gun aiming at the current situation of the prior art so as to prevent a large amount of powder from flowing into the outlet of a spray pipe.

The second technical problem to be solved by the invention is to provide a cold spraying gun to promote the powder in the powder cavity to flow to the outlet of the spray pipe.

The technical scheme adopted by the invention for solving the first technical problem is as follows: a cold spray coating gun comprising:

the gas inlet is positioned at the upstream of the gas outlet along the gas flowing direction, the length direction of the spray pipe is a first axial direction, and the direction surrounding the first axial direction is a first circumferential direction;

the powder barrel is sleeved on the periphery of the side wall of the spray pipe and extends along the first axial direction, an annular powder cavity is formed between the inner peripheral wall of the powder barrel and the side wall of the spray pipe, and a powder outlet is formed at the end part, close to the gas outlet, of the powder barrel;

the method is characterized in that:

along the gas flowing direction, the powder outlet is positioned at the downstream of the gas outlet of the spray pipe and is opposite to the gas outlet;

the cold spray gun further comprises:

the filter cylinder is arranged between the powder outlet of the powder cylinder and the gas outlet of the spray pipe and extends along the first axial direction, the first end part of the filter cylinder is opposite to and communicated with the gas outlet of the spray pipe, the second end part of the filter cylinder is opposite to and communicated with the powder outlet of the powder cylinder, the cylinder wall of the filter cylinder is opposite to the powder cavity, and a plurality of first filter holes penetrating through the wall thickness are distributed on the cylinder wall of the filter cylinder at intervals, so that powder in the powder cavity can enter the filter cylinder through the first filter holes.

Therefore, the high-speed airflow jetted from the gas outlet of the jet pipe can penetrate through the filter cylinder along the first axial direction, and in the process, negative pressure can be generated inside the filter cylinder, so that powder in the powder cavity enters the filter cylinder through the first filter hole under the action of the negative pressure and is jetted out along with the high-speed airflow. According to the invention, the filter cylinder can intercept a part of powder, so that the powder can uniformly enter the filter cylinder, and the problem that the outlet of the spraying gun is blocked due to the fact that a large amount of powder flows in is avoided.

Preferably, the first filter holes are uniformly distributed on the wall of the filter cylinder.

Preferably, the caliber of the powder outlet of the powder barrel is larger than the caliber of the gas outlet of the spray pipe; the length of the filter cylinder in the first axial direction is larger than the caliber of a powder outlet of the powder cylinder. So that the powder can smoothly enter the filter cylinder and be discharged from the powder outlet of the powder cylinder.

In each of the above solutions, the powder in the powder cavity near the position of the filter cartridge can flow to the filter cartridge under the negative pressure, and the powder far from the position of the filter cartridge may have the problems of accumulation and stagnation, so to further solve the second technical problem, preferably, the powder device further comprises a roller extending along the first axial direction, which is sleeved on the periphery of the side wall of the spray pipe in a manner of rotating along the first circumferential direction and is located in the powder cavity, so as to divide the powder cavity into an annular first cavity located on the periphery of the side wall of the spray pipe, in the roller and an annular second cavity located outside the roller, and the end of the second cavity near the gas inlet is provided with a gas inlet;

a second blade which is connected with the roller, surrounds the peripheral wall of the roller and spirally extends along the first axial direction is arranged in the second cavity, and the second blade can drive the roller to rotate under the action of the gas flow input by the gas inlet;

meanwhile, a first blade which surrounds the side wall of the spray pipe and spirally extends along the first axial direction is arranged in the first chamber, and the first blade is arranged to drive the powder in the first chamber to flow to the powder outlet under the rotating state of the roller.

Thus, the powder can flow toward the filter cartridge under the push of the first blade.

Meanwhile, the second blade can generate spiral airflow, and the spiral airflow can promote the flow of powder to a certain extent.

Preferably, the helical direction of the first blade is opposite to the helical direction of the second blade.

In order to prevent a large amount of powder from flowing to the filter cylinder, preferably, a filter plate is arranged at the end part of the first chamber close to the powder outlet, and the plate surface of the filter plate is opposite to the first chamber and is provided with a plurality of second filter holes which penetrate through the plate thickness at intervals.

The aperture of the second filtering hole can be designed according to the particle size of the powder particles and the powder feeding speed.

Preferably, the filter plate has at least two, be first filter plate, second filter plate respectively, and both face is relative and along first axial arrangement, and first filter plate links to each other with the cylinder, and can rotate along with the cylinder, the second filter plate is located the low reaches of first filter plate, and relative the fixing is in the powder intracavity. Therefore, the cooperation between the rotating first filter plate and the fixed second filter plate is beneficial to powder to pass through the filter plates, and the powder is prevented from being accumulated at the upstream position of the filter plates.

Preferably, the second filter holes on the second filter plate are circular and uniformly distributed on the second filter plate;

the plurality of second filter holes on the first filter plate are arranged at intervals along the first circumferential direction, are integrally in a spiral blade shape, and the spiral direction of the second filter holes is consistent with the spiral direction of the first blades. Thereby further promoting the passage of the powder through the filter plate.

Preferably, along the gas flowing direction, the nozzle has a gas inlet section, a contraction section and an expansion section which are sequentially communicated, the gas inlet section extends along the first axial direction, the port of the gas inlet section is the gas inlet of the nozzle, the flow area on the cross section of the contraction section is gradually reduced along the gas flowing direction, the flow area on the cross section of the expansion section is gradually increased along the gas flowing direction, and the port of the expansion section is the gas outlet of the nozzle;

along the powder flowing direction, the powder cavity is provided with an upstream part and a downstream part which are communicated in sequence, the upstream part is arranged corresponding to the air inlet section of the spray pipe so as to arrange the roller therein, and the downstream part is arranged corresponding to the contraction section and the expansion section of the spray pipe. In this way, the spiral air flow generated by the rotation of the second blades can promote the powder in the downstream part to flow to the filter cylinder.

In each of the above solutions, in order to improve the spraying precision, preferably, the powder spraying device further includes a protection cylinder, which is sleeved on the periphery of the powder cylinder and extends along the first axial direction, an inner peripheral wall of the protection cylinder is opposite to an outer peripheral wall of the powder cylinder and forms an annular protection cavity, an end of the protection cavity, which is close to the gas inlet, is provided with a shielding gas inlet for inputting shielding gas, an end of the protection cavity, which is close to the gas outlet, is provided with a shielding gas outlet for outputting shielding gas, and the shielding gas outlet is located on the periphery of the powder outlet of the powder cavity.

Therefore, the invention can restrain the gas jet flow at the outlet through the airflow protection function at the outermost layer, can effectively reduce the divergence area of the gas-solid mixture in the spraying process, improves the cold spraying precision, and also reduces the loss of powder caused by divergence.

Compared with the prior art, the invention has the advantages that: the powder outlet is positioned at the downstream of the gas outlet of the spray pipe and is opposite to the gas outlet, the filter cylinder is additionally arranged between the powder outlet of the powder cylinder and the gas outlet of the spray pipe, the first end part of the filter cylinder is opposite to and communicated with the gas outlet of the spray pipe, the second end part of the filter cylinder is opposite to and communicated with the powder outlet of the powder cylinder, the cylinder wall of the filter cylinder is opposite to the powder cavity, and a plurality of first filter holes penetrating through the wall thickness are distributed at intervals, so that high-speed airflow jetted from the gas outlet of the spray pipe can penetrate through the filter cylinder along a first axial direction, and in the process, negative pressure can be generated inside the filter cylinder, so that the powder in the powder cavity enters the filter cylinder through the first filter holes under the action of the negative pressure and is jetted out along with the high-speed airflow. In addition, the filter cylinder can intercept a part of powder, so that the powder can uniformly enter the filter cylinder, and the problem that the outlet of the spraying gun is blocked due to the fact that a large amount of powder flows into the filter cylinder is solved.

Drawings

FIG. 1 is a schematic structural diagram of an embodiment of the present invention;

FIG. 2 is a schematic view of another embodiment of the present invention;

FIG. 3 is a longitudinal cross-sectional view of an embodiment of the present invention;

FIG. 4 is an exploded perspective view of an embodiment of the present invention;

fig. 5 is a schematic structural diagram of a roller according to an embodiment of the present invention.

Detailed Description

The invention is described in further detail below with reference to the accompanying examples.

As shown in fig. 1 to 5, a cold spray gun according to a preferred embodiment of the present invention includes a spray tube 1, a powder cartridge 2, a filter cartridge 3, a drum 4, a filter sheet 5, and a protective cartridge 6.

The longitudinal direction of the nozzle 1 is a first axial direction, and the direction around the first axial direction is a first circumferential direction. Along the gas flow direction, the spray pipe 1 is provided with an air inlet section 11, a contraction section 12 and an expansion section 13 which are sequentially communicated, the air inlet section 11 extends along the first axial direction, the port of the air inlet section 11 is a gas inlet 1a of the spray pipe 1, the flow area on the cross section of the contraction section 12 is gradually reduced along the gas flow direction, the flow area on the cross section of the expansion section 13 is gradually increased along the gas flow direction, and the port of the expansion section 13 is a gas outlet 1b of the spray pipe 1.

The powder barrel 2 is sleeved on the periphery of the side wall of the spray pipe 1 and extends along the first axial direction, and an annular powder cavity 20 is formed between the inner peripheral wall of the powder barrel 2 and the side wall of the spray pipe 1. The end of the powder barrel 2 close to the gas outlet 1b is provided with a powder outlet 2b, and the end of the powder barrel 2 close to the gas inlet 1a is provided with a powder inlet. The powder outlet 2b is located downstream of the gas outlet 1b of the nozzle 1 in the gas flow direction, and is opposite to the gas outlet 1b. Meanwhile, the powder chamber 20 has an upstream portion 23 and a downstream portion 24 which are communicated with each other in this order in the flow direction of the powder, the upstream portion 23 being disposed corresponding to the air inlet section 11 of the nozzle 1, and the downstream portion 24 being disposed corresponding to the contraction section 12 and the expansion section 13 of the nozzle 1. Meanwhile, in the present embodiment, the powder cartridge 2 is formed by connecting two parts of the first axial upstream portion 23 and the first axial downstream portion 24, and the connection is a threaded connection.

The filter cartridge 3 is arranged between the powder outlet 2b of the powder cartridge 2 and the gas outlet 1b of the spray pipe 1 and extends along the first axial direction, the first end part of the filter cartridge 3 is opposite to and communicated with the gas outlet 1b of the spray pipe 1, the second end part of the filter cartridge 3 is opposite to and communicated with the powder outlet 2b of the powder cartridge 2, the wall of the filter cartridge 3 is opposite to the powder cavity 20, and a plurality of first filter holes 30 penetrating through the wall thickness are uniformly distributed on the wall of the filter cartridge 3 at equal intervals, so that powder in the powder cavity 20 can enter the filter cartridge 3 through the first filter holes 30. In this embodiment, the diameter of the powder outlet 2b of the powder barrel 2 is larger than the diameter of the gas outlet 1b of the nozzle 1; the length of the filter cartridge 3 in the first axial direction is larger than the diameter of the powder outlet 2b of the powder cartridge 2.

As shown in fig. 3, 4 and 5, the roller 4 extends along a first axial direction, and is rotatably sleeved on the outer periphery of the side wall of the nozzle 1 along the first circumferential direction, and is located in the upstream portion 23 of the powder cavity 20, so as to divide the upstream portion 23 of the powder cavity 20 into an annular first chamber 21 located on the outer periphery of the side wall of the nozzle 1 and inside the roller 4 and an annular second chamber 22 located outside the roller 4, and an end portion of the second chamber 22 close to the gas inlet 1a is provided with a gas inlet 22a; a second vane 221 connected to the drum 4, surrounding the outer circumferential wall of the drum 4 and spirally extending along the first axial direction is arranged in the second chamber 22, and the second vane 221 is arranged to drive the drum 4 to rotate under the action of the gas flow input from the gas inlet 22a; meanwhile, a first blade 211 which surrounds the side wall of the nozzle 1 and extends spirally along a first axial direction is arranged in the first chamber 21, the spiral direction of the first blade 211 is opposite to the spiral direction of the second blade 221, and the first blade 211 is arranged to drive the powder in the first chamber 21 to flow to the powder outlet 2b under the rotating state of the roller 4.

As shown in fig. 3 and 4, the filter sheet 5 is provided at an end portion of the first chamber 21 near the powder outlet 2b, and a plurality of second filter holes 50 penetrating the thickness of the sheet are spaced apart from each other and are formed on a surface of the filter sheet 5 facing the first chamber 21. In this embodiment, the filter plates 5 include two first filter plates 51 and two second filter plates 52, the surfaces of the first filter plates 51 and the second filter plates 52 are opposite and arranged along the first axial direction, the first filter plates 51 are connected with the drum 4 and can rotate along with the drum 4, and the second filter plates 52 are disposed at the downstream of the first filter plates 51 and are relatively fixed in the powder chamber 20. Meanwhile, the second filter holes 50 on the second filter plate 52 are circular and are uniformly distributed on the second filter plate 52; the plurality of second filter holes 50 of the first filter sheet 51 are arranged at intervals in the first circumferential direction, and are formed in a spiral blade shape as a whole, and the spiral direction coincides with the spiral direction of the first blade 211.

The protection cylinder 6 is sleeved on the periphery of the powder cylinder 2 and extends along the first axial direction, the inner peripheral wall of the protection cylinder 6 is opposite to the outer peripheral wall of the powder cylinder 2 and is provided with an annular protection cavity 60, the end part, close to the gas inlet 1a, of the protection cavity 60 is provided with a protection gas inlet 60a for inputting protection gas, the end part, close to the gas outlet 1b, of the protection cavity 60 is provided with a protection gas outlet 60b for outputting protection gas, and the protection gas outlet 60b is positioned on the periphery of the powder outlet 2b of the powder cavity 20. Similarly, the protection cylinder 6 is formed by connecting two parts corresponding to the upstream part 23 and the downstream part 24 in the first axial direction, and the connection mode is a threaded connection.

The acceleration process of the gas in this example is: the acceleration of the gas is completed in the nozzle 1, the external gas enters the nozzle 1 through the gas inlet 1a, reaches the sonic velocity at the throat part between the contraction section 12 and the expansion section 13 of the nozzle 1, then diffuses in the expansion section 13 until the acceleration reaches the supersonic velocity, mixes with the powder in the filter cartridge 3 at the gas outlet 1b, and then is ejected out of the spray gun.

The powder conveying process comprises the following steps: the powder is transported in the powder chamber 20, and when external high-pressure gas enters the second chamber 22 of the powder chamber 20 through the gas inlet 22a, the gas drives the roller 4 to rotate in the first circumferential direction by blowing the second vane 221. Since the second vane 221 is opposite to the first vane 211, when the drum 4 rotates clockwise, the first vane 211 in the drum 4 will bring the powder to rotate counterclockwise, and when the rotating speed reaches a certain value, the powder will be pumped out of the drum 4 by the centrifugal force and the first vane 211, and reach the downstream portion 24 of the powder chamber 20 through the filter plate 5.

When the external gas reaches the contraction section 12 of the nozzle 1, according to the law of conservation of energy, the pressure P, the density ρ and the temperature T of the gas in the nozzle 1 are all continuously reduced, and the velocity V is continuously increased, that is, the gas flow in the nozzle 1 undergoes the expansion process of pressure reduction, temperature reduction and acceleration. Therefore, when the gas flow reaches the end of the expanding section 13, assuming that the pressure at this time is P1 and the pressure of the powder at the end of the powder chamber 20 is P2, since P1> P2, a pressure difference is generated between them, according to the Bernoulli equation:

it is known that at different pressures at the two ends, gas flows from a higher pressure location to a lower pressure location. Thus, the gas is further accelerated in the powder chamber 20. In addition, due to the action of the second blades 221 on the drum 4, the gas in the powder chamber 20 pushes the powder forward in a spiral direction to move, and due to the smaller particle size of the powder, the powder moves spirally with the gas, and the movement in this way has the advantage that the powder can pass through the filter cartridge 3 more uniformly, and the risk of powder blockage caused by the downward deposition of the powder under the action of gravity is reduced. Finally, the powder is mixed with supersonic gas through a filter cylinder 3.

The process of restricting the airflow is: the external gas enters the protection cavity 60 through the protection gas inlet 60a and then is discharged from the protection gas outlet 60b, the discharged protection gas prevents the gas-solid mixture sprayed from the powder outlet 2b from diffusing to a certain degree, so that the mixture is sprayed out of the gun mouth relatively intensively, and the spraying precision is improved.

Claims

1. A cold spray coating gun comprising:

a nozzle (1) having a gas inlet (1 a) and a gas outlet (1 b), the gas inlet (1 a) being located upstream of the gas outlet (1 b) in a gas flow direction, the nozzle (1) having a length direction defined as a first axial direction and a direction around the first axial direction defined as a first circumferential direction;

the powder barrel (2) is sleeved on the periphery of the side wall of the spray pipe (1) and extends along the first axial direction, an annular powder cavity (20) is formed between the inner peripheral wall of the powder barrel (2) and the side wall of the spray pipe (1), and a powder outlet (2 b) is formed in the end part, close to the gas outlet (1 b), of the powder barrel (2);

the method is characterized in that:

said powder outlet (2 b) being located downstream of the gas outlet (1 b) of said lance (1) and opposite to the gas outlet (1 b) in the direction of gas flow;

the cold spray gun further comprises:

the filter cartridge (3) is arranged between the powder outlet (2 b) of the powder cartridge (2) and the gas outlet (1 b) of the spray pipe (1) and extends along the first axial direction, the first end part of the filter cartridge (3) is opposite to and communicated with the gas outlet (1 b) of the spray pipe (1), the second end part of the filter cartridge (3) is opposite to and communicated with the powder outlet (2 b) of the powder cartridge (2), the cartridge wall of the filter cartridge (3) is opposite to the powder cavity (20), and a plurality of first filter holes (30) penetrating through the wall thickness are distributed on the cartridge wall of the filter cartridge (3) at intervals, so that powder in the powder cavity (20) can enter the filter cartridge (3) through the first filter holes (30).

2. The cold spray gun of claim 1, wherein: the first filtering holes (30) are uniformly distributed on the wall of the filter cylinder (3).

3. The cold spray gun of claim 1, wherein: the caliber of the powder outlet (2 b) of the powder barrel (2) is larger than that of the gas outlet (1 b) of the spray pipe (1); the length of the filter cylinder (3) in the first axial direction is larger than the caliber of the powder outlet (2 b) of the powder cylinder (2).

4. The cold spray gun according to any one of claims 1 to 3, wherein: the device also comprises a roller (4) extending along the first axial direction, the roller is sleeved on the periphery of the side wall of the spray pipe (1) in a manner of rotating along the first circumferential direction and is positioned in the powder cavity (20), the powder cavity (20) is divided into an annular first cavity (21) positioned on the periphery of the side wall of the spray pipe (1) and in the roller (4) and an annular second cavity (22) positioned outside the roller (4), and a gas inlet (22 a) is arranged at the end part of the second cavity (22) close to the gas inlet (1 a);

a second blade (221) which is connected with the roller (4), surrounds the peripheral wall of the roller (4) and spirally extends along the first axial direction is arranged in the second chamber (22), and the second blade (221) is arranged to drive the roller (4) to rotate under the action of the gas flow input by the gas inlet (22 a);

meanwhile, a first blade (211) which surrounds the side wall of the spray pipe (1) and spirally extends along the first axial direction is arranged in the first chamber (21), and under the state that the roller (4) rotates, the first blade (211) is arranged to drive the powder in the first chamber (21) to flow to the powder outlet (2 b).

5. The cold spray gun of claim 4, wherein: the spiral direction of the first blade (211) is opposite to the spiral direction of the second blade (221).

6. The cold spray gun of claim 4, wherein: the end part of the first chamber (21) close to the powder outlet (2 b) is provided with a filter plate (5), the plate surface of the filter plate (5) is opposite to the first chamber (21), and a plurality of second filter holes (50) penetrating through the plate thickness are distributed at intervals.

7. The cold spray gun of claim 6, wherein: the filter comprises a powder cavity (20), at least two filter plates (5) and a roller (4), wherein the filter plates are respectively a first filter plate (51) and a second filter plate (52), the surfaces of the first filter plate and the second filter plate are opposite and are arranged along a first axial direction, the first filter plate (51) is connected with the roller (4) and can rotate along with the roller (4), and the second filter plate (52) is arranged at the downstream of the first filter plate (51) and is relatively fixed in the powder cavity (20).

8. The cold spray gun of claim 7, wherein: the second filter holes (50) on the second filter plate (52) are circular and are uniformly distributed on the second filter plate (52);

the plurality of second filter holes (50) on the first filter plate (51) are arranged at intervals along the first circumferential direction, are in a spiral blade shape as a whole, and have the spiral direction consistent with the spiral direction of the first blade.

9. The cold spray gun of claim 4, wherein: along the gas flowing direction, the spray pipe (1) is provided with a gas inlet section (11), a contraction section (12) and an expansion section (13) which are sequentially communicated, the gas inlet section (11) extends along the first axial direction, the port of the gas inlet section (11) is a gas inlet (1 a) of the spray pipe (1), the flow area on the cross section of the contraction section (12) is gradually reduced along the gas flowing direction, the flow area on the cross section of the expansion section (13) is gradually increased along the gas flowing direction, and the port of the expansion section (13) is a gas outlet (1 b) of the spray pipe (1);

along the powder flowing direction, the powder cavity (20) is provided with an upstream part (23) and a downstream part (24) which are communicated in sequence, the upstream part (23) is arranged corresponding to the air inlet section (11) of the spray pipe (1) so as to arrange the roller (4) therein, and the downstream part (24) is arranged corresponding to the contraction section (12) and the expansion section (13) of the spray pipe (1).

10. The cold spray gun according to any one of claims 1 to 3, wherein: the powder mixing device is characterized by further comprising a protection cylinder (6) which is sleeved on the periphery of the powder cylinder (2) and extends along the first axial direction, the inner peripheral wall of the protection cylinder (6) is opposite to the outer peripheral wall of the powder cylinder (2) and is provided with an annular protection cavity (60), a protective gas inlet (60 a) for inputting protective gas is formed in the end portion, close to the gas inlet (1 a), of the protection cavity (60), a protective gas outlet (60 b) for outputting protective gas is formed in the end portion, close to the gas outlet (1 b), of the protection cavity (60), and the protective gas outlet (60 b) is located on the periphery of the powder outlet (2 b) of the powder cavity (20).