A cold spray gun

Abstract

A cold spray gun includes a spray pipe and a powder cylinder. The spray pipe has a gas inlet and a gas outlet. The powder cylinder is sleeved on the outer periphery of the side wall of the spray pipe and extends along the first axial direction of the spray pipe. An annular powder chamber is formed between the inner peripheral wall of the powder cylinder and the side wall of the spray pipe, and a powder outlet is provided at the end of the powder cylinder close to the gas outlet. Along the gas flow direction, the powder outlet is located downstream of the gas outlet of the spray pipe and is opposite to the gas outlet. It also includes a filter cartridge, which 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 of the filter cartridge is opposite to and communicated with the gas outlet of the spray pipe, the second end of the filter cartridge is opposite to and communicated with the powder outlet of the powder cylinder, the barrel wall of the filter cartridge is opposite to the powder chamber, and a plurality of first filter holes penetrating the wall thickness are spaced apart, so that the powder in the powder chamber can enter the filter cartridge through the first filter holes. Compared with the prior art, the present invention can prevent a large amount of powder from pouring into the outlet of the spray pipe.

Description

Technical Field

[0001] The present invention belongs to the technical field of material surface spraying, and particularly relates to a cold spraying gun. Background Art

[0002] The full name of cold spraying is Cold Gas Dynamic Spray (abbreviated as GCDS). The cold spraying system mainly includes a high-pressure gas source, a spray gun system, a gas temperature control system, a powder feeding system, a gas regulation system, and a powder recovery system. The cold spraying technology uses high-pressure gas (nitrogen, helium, or compressed air) as a carrier. Through a Laval nozzle, the powder particles are accelerated to 300 - 1200 m / s, and at a high speed in the solid state, they impact the surface of the substrate. The high-speed gas flow drives the powder particles to undergo "adiabatic shear instability" to cause plastic deformation of the powder, thereby forming a coating. The formed coating has advantages such as high density, low porosity, no oxidation, and maximizing thermal conductivity and electrical conductivity, so it has been widely used in industries such as aerospace and the automotive industry.

[0003] The Laval nozzle used in cold spraying is also called a supersonic nozzle. Along the flow direction of the gas flow, the inner diameter of the first half of the Laval nozzle gradually decreases to form a contraction section, and the inner diameter of the second half gradually increases to form an expansion section. The connection between the contraction section and the expansion section forms a narrow throat. The gas at the inlet flows into the first half of the nozzle under high pressure, passes through the narrow throat, and then escapes from the second half. This structure can change the speed of the gas flow due to the change in the cross-sectional area of the nozzle, so that the gas flow changes from subsonic to sonic, and then accelerates to supersonic. Under supersonic conditions, the powder particles in the gas flow will deposit on the surface of the substrate to form a coating. However, under supersonic conditions, when the gas flow and the powder particles are ejected from the nozzle of the Laval nozzle, they will quickly diverge, resulting in a decrease in the spraying accuracy.

[0004] To this end, the utility model patent "A High-Speed Laser Spraying Device" with the patent number 201822205131.X (the authorized announcement number is CN209722309U) discloses a high-speed laser spraying device, including a laser cavity tube, a nozzle, a movable baffle ring, and a protective air nozzle. A high-pressure air pipe is connected to the left part of the laser cavity tube. The right part of the inner cavity of the laser cavity tube is threadedly connected with a nozzle. A powder feeding pipe is arranged inside the side wall of the connecting sleeve. The inner side wall of the connecting sleeve is threadedly connected with a protective air nozzle. A first annular conical-like gap is arranged between the movable baffle ring and the outer side wall of the nozzle. A second annular conical gap is formed between the protective air nozzle and the movable baffle ring. A protective air pipe is arranged inside the side wall of the protective air nozzle. The second annular conical gap is communicated with the protective air pipe. A clamping groove is arranged on the right part of the inner side wall of the connecting sleeve, and a snap spring is clamped in the clamping groove. In this way, the protective gas forms a protective air curtain outside the spraying movement path, effectively preventing the spraying powder from splashing out. And by adjusting the thread tightness between the movable baffle ring and the connecting sleeve, the size of the first annular conical-like or conical gap is adjusted, so as to control the spraying powder flow rate; by adjusting the thread tightness between the protective air nozzle and the movable baffle ring and the connecting sleeve, the size of the second annular conical gap is adjusted, so as to control the protective gas pressure.

[0005] Although the above-mentioned utility model patent can control the spraying powder flow rate by adjusting the movable baffle ring, there is still a problem that a large number of powder particles rush into the outlet of the spray pipe together, causing congestion of the powder particles, thus affecting the normal operation of the spray gun. Summary of the Invention

[0006] The first technical problem to be solved by the present invention is to provide a cold spray gun for the current situation of the prior art to avoid a large amount of powder from rushing into the outlet of the spray pipe.

[0007] The second technical problem to be solved by the present invention is to provide a cold spray gun to promote the flow of the powder in the powder chamber towards the outlet of the spray pipe.

[0008] The technical solution adopted by the present invention to solve the above first technical problem is: a cold spray gun, including:

[0009] A spray pipe having a gas inlet and a gas outlet. Along the gas flow direction, the gas inlet is located upstream of the gas outlet, and the length direction of the spray pipe is defined as the first axial direction, and the direction around the first axial direction is defined as the first circumferential direction;

[0010] A powder cylinder sleeved on the outer periphery of the side wall of the spray pipe and extending along the above first axial direction. An annular powder chamber is formed between the inner peripheral wall of the powder cylinder and the side wall of the spray pipe, and a powder outlet is provided at the end of the powder cylinder close to the gas outlet;

[0011] It is characterized in that:

[0012] Along the gas flow direction, the powder outlet is located downstream of the gas outlet of the above-mentioned nozzle and is opposite to the gas outlet;

[0013] The cold spray gun further includes:

[0014] A filter cartridge, which is arranged between the powder outlet of the above-mentioned powder cartridge and the gas outlet of the nozzle and extends along the above-mentioned first axial direction. The first end of the filter cartridge is opposite to and communicates with the gas outlet of the nozzle, the second end of the filter cartridge is opposite to and communicates with the powder outlet of the powder cartridge, the barrel wall of the filter cartridge is opposite to the above-mentioned powder chamber, and a plurality of first filter holes penetrating the wall thickness are distributed at intervals on the barrel wall of the filter cartridge, so that the powder in the powder chamber can enter the filter cartridge through the first filter holes.

[0015] In this way, the high-speed air flow ejected from the gas outlet of the nozzle can pass through the filter cartridge along the first axial direction. During this process, a negative pressure will be generated inside the filter cartridge, so that the powder in the powder chamber enters the filter cartridge through the first filter holes under the action of the negative pressure and is ejected together with the high-speed air flow. The setting of the filter cartridge in the present invention can intercept a part of the powder, so that the powder enters the filter cartridge evenly, thereby avoiding the problem of blockage of the spray gun outlet caused by a large influx of powder.

[0016] Preferably, the first filter holes are evenly distributed on the barrel wall of the filter cartridge.

[0017] Preferably, the caliber of the powder outlet of the powder cartridge is larger than the caliber of the gas outlet of the nozzle; the length of the filter cartridge in the first axial direction is greater than the caliber of the powder outlet of the powder cartridge. Thus, the powder can smoothly enter the filter cartridge and be discharged from the powder outlet of the powder cartridge.

[0018] In the above-mentioned various solutions, the powder near the filter cartridge in the powder chamber can flow towards the filter cartridge under the action of the negative pressure, while the powder far from the filter cartridge may have problems of accumulation and stagnation. Therefore, to further solve the above-mentioned second technical problem, preferably, it further includes a roller extending along the above-mentioned first axial direction, which is sleeved on the outer periphery of the side wall of the nozzle in a manner that can rotate along the above-mentioned first circumferential direction and is located in the powder chamber, dividing the powder chamber into an annular first chamber located outside the side wall of the nozzle and inside the roller and an annular second chamber located outside the roller. The end of the second chamber close to the gas inlet is provided with a gas inlet;

[0019] A second blade is arranged in the second chamber, which is connected to the roller, surrounds the outer peripheral wall of the roller and extends spirally along the first axial direction. The second blade is arranged to drive the roller to rotate under the action of the air flow input from the gas inlet;

[0020] At the same time, a first blade is arranged in the first chamber, which surrounds the side wall of the nozzle and extends spirally along the first axial direction. When the roller rotates, the first blade is arranged to drive the powder in the first chamber to flow towards the powder outlet.

[0021] Thus, the powder can flow towards the filter cartridge under the push of the first blade.

[0022] Meanwhile, the arrangement of the second blade in the present invention can generate a spiral air flow, which can promote the flow of the powder to a certain extent.

[0023] Preferably, the spiral direction of the first blade is opposite to that of the second blade.

[0024] To prevent a large amount of powder from surging towards the filter cartridge, preferably, a filter plate is provided at the end of the first chamber close to the powder outlet. The plate surface of the filter plate faces the first chamber, and a plurality of second filter holes penetrating the plate thickness are distributed at intervals.

[0025] The aperture of the second filter holes can be designed according to the particle size of the powder particles and the powder feeding speed.

[0026] Preferably, there are at least two filter plates, namely a first filter plate and a second filter plate. Their plate surfaces face each other and are arranged along the first axial direction. The first filter plate is connected to the drum and can rotate with the drum. The second filter plate is arranged downstream of the first filter plate and is relatively fixed in the powder chamber. In this way, the cooperation between the rotating first filter plate and the fixed second filter plate is beneficial for the powder to pass through the filter plate and avoid powder accumulation at the upstream position of the filter plate.

[0027] Preferably, the second filter holes on the second filter plate are circular and are evenly distributed on the second filter plate;

[0028] The plurality of second filter holes on the first filter plate are arranged at intervals along the first circumferential direction and are integrally in the shape of a spiral blade, and the spiral direction is the same as that of the first blade. Thereby, it can further promote the powder to pass through the filter plate.

[0029] Preferably, along the gas flow direction, the spray pipe has a sequentially connected intake section, a contraction section and an expansion section. The intake section extends along the first axial direction, and the port of the intake section is the gas inlet of the spray pipe. The flow area of the cross section of the contraction section gradually decreases along the gas flow direction, and the flow area of the cross section of the expansion section gradually increases along the gas flow direction. The port of the expansion section is the gas outlet of the spray pipe;

[0030] Along the powder flow direction, the powder chamber has a sequentially connected upstream part and a downstream part. The upstream part corresponds to the intake section of the spray pipe for the drum to be arranged therein, and the downstream part corresponds 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 blade can promote the powder in the downstream part to flow towards the filter cartridge.

[0031] In the above-mentioned various solutions, in order to improve the spraying accuracy, preferably, a protective cylinder is further included, which is sleeved on the outer periphery of the powder cylinder and extends along the first axial direction. The inner peripheral wall of the protective cylinder faces the outer peripheral wall of the powder cylinder and forms an annular protective cavity. A protective gas inlet for inputting protective gas is provided at the end of the protective cavity close to the gas inlet, and a protective gas outlet for outputting protective gas is provided at the end of the protective cavity close to the gas outlet. The protective gas outlet is located outside the powder outlet of the powder cavity.

[0032] In this way, the present invention can constrain the outlet gas jet through the outermost airflow protection, effectively reduce the divergence area of the gas-solid mixture during the spraying process, improve the accuracy of cold spraying, and also reduce the loss of powder due to divergence.

[0033] Compared with the prior art, the advantages of the present invention are as follows: By locating the powder outlet downstream of the gas outlet of the spray pipe and opposite to the gas outlet, and adding a filter cartridge between the powder outlet of the powder cylinder and the gas outlet of the spray pipe. The first end of the filter cartridge is opposite to and communicates with the gas outlet of the spray pipe, the second end of the filter cartridge is opposite to and communicates with the powder outlet of the powder cylinder, and the barrel wall of the filter cartridge faces the powder cavity and is provided with a plurality of first filter holes penetrating the wall thickness at intervals. Thus, the high-speed airflow ejected from the gas outlet of the spray pipe can pass through the filter cartridge along the first axial direction. During this process, a negative pressure will be generated inside the filter cartridge, causing the powder in the powder cavity to enter the filter cartridge through the first filter holes under the action of the negative pressure and be ejected together with the high-speed airflow. And the setting of the filter cartridge in the present invention can intercept part of the powder, enabling the powder to enter the filter cartridge evenly, thereby avoiding the problem of blockage at the outlet of the spray gun caused by a large influx of powder. Description of the Drawings

[0034] Figure 1 It is a schematic structural diagram of an embodiment of the present invention;

[0035] Figure 2 It is a schematic structural diagram of an embodiment of the present invention from another perspective;

[0036] Figure 3 It is a longitudinal sectional view of an embodiment of the present invention;

[0037] Figure 4 It is an exploded perspective view of an embodiment of the present invention;

[0038] Figure 5 It is a schematic structural diagram of the drum in an embodiment of the present invention. Detailed Description of the Embodiment

[0039] The present invention will be further described in detail below in conjunction with the embodiments of the drawings.

[0040] Such as Figures 1 to 5As shown in the figure, it is a preferred embodiment of a cold spray gun of the present invention. The cold spray gun includes a spray pipe 1, a powder cylinder 2, a filter cylinder 3, a roller 4, a filter plate 5 and a protection cylinder 6.

[0041] The length direction of the spray pipe 1 is defined as the first axial direction, and the direction around the first axial direction is the first circumferential direction. Along the gas flow direction, the spray pipe 1 has an air inlet section 11, a contraction section 12 and an expansion section 13 that are connected in sequence. The air inlet section 11 extends along the first axial direction, and the port of the air inlet section 11 is the gas inlet 1a of the spray pipe 1. The flow area of the cross section of the contraction section 12 gradually decreases along the gas flow direction, and the flow area of the cross section of the expansion section 13 gradually increases along the gas flow direction. The port of the expansion section 13 is the gas outlet 1b of the spray pipe 1.

[0042] The above-mentioned powder cylinder 2 is sleeved on the outer 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 cylinder 2 and the side wall of the spray pipe 1. The end of the powder cylinder 2 close to the gas outlet 1b is provided with a powder outlet 2b, and the end of the powder cylinder 2 close to the gas inlet 1a is provided with a powder inlet. Along the gas flow direction, the powder outlet 2b is located downstream of the gas outlet 1b of the spray pipe 1 and is opposite to the gas outlet 1b. At the same time, along the powder flow direction, the powder cavity 20 has a upstream part 23 and a downstream part 24 that are connected in sequence. The upstream part 23 corresponds to the air inlet section 11 of the spray pipe 1, and the downstream part 24 corresponds to the contraction section 12 and the expansion section 13 of the spray pipe 1. At the same time, in this embodiment, the powder cylinder 2 is composed of two parts corresponding to the upstream part 23 and the downstream part 24 in the first axial direction, and the connection method is a threaded connection.

[0043] The above-mentioned filter cylinder 3 is arranged between the powder outlet 2b of the powder cylinder 2 and the gas outlet 1b of the spray pipe 1 and extends along the first axial direction. The first end of the filter cylinder 3 is opposite to and communicated with the gas outlet 1b of the spray pipe 1, the second end of the filter cylinder 3 is opposite to and communicated with the powder outlet 2b of the powder cylinder 2, the cylinder wall of the filter cylinder 3 is opposite to the powder cavity 20, and a plurality of first filter holes 30 penetrating the wall thickness are evenly distributed at equal intervals on the cylinder wall of the filter cylinder 3, so that the powder in the powder cavity 20 can enter the filter cylinder 3 through the first filter holes 30. In this embodiment, the diameter of the powder outlet 2b of the powder cylinder 2 is larger than the diameter of the gas outlet 1b of the spray pipe 1; the length of the filter cylinder 3 in the first axial direction is larger than the diameter of the powder outlet 2b of the powder cylinder 2.

[0044] As Figure 3 、 4As shown in FIGS. 5, the above-mentioned roller 4 extends along the first axial direction and is sleeved on the outer periphery of the side wall of the nozzle 1 in a manner that can rotate along the first circumferential direction, and is located in the upstream part 23 of the powder chamber 20. The upstream part 23 of the powder chamber 20 is divided into an annular first chamber 21 located inside the roller 4 and outside the side wall of the nozzle 1 and an annular second chamber 22 located outside the roller 4. The end of the second chamber 22 close to the gas inlet 1a is provided with a gas inlet 22a; a second blade 221 is provided in the second chamber 22, which is connected to the roller 4, surrounds the outer peripheral wall of the roller 4 and extends spirally along the first axial direction. The second blade 221 is arranged to drive the roller 4 to rotate under the action of the air flow input from the gas inlet 22a; at the same time, a first blade 211 is provided in the first chamber 21, which surrounds the side wall of the nozzle 1 and extends spirally along the first axial direction. The spiral direction of the first blade 211 is opposite to that of the second blade 221. In the rotating state of the roller 4, the first blade 211 is arranged to drive the powder in the first chamber 21 to flow towards the powder outlet 2b.

[0045] As Figure 3 , 4 shown, the above-mentioned filter plate 5 is arranged at the end of the first chamber 21 close to the powder outlet 2b. The plate surface of the filter plate 5 faces the first chamber 21, and a plurality of second filter holes 50 penetrating the plate thickness are spaced apart. In this embodiment, there are two filter plates 5, namely a first filter plate 51 and a second filter plate 52. Their plate surfaces face each other and are arranged along the first axial direction. The first filter plate 51 is connected to the roller 4 and can rotate with the roller 4. The second filter plate 52 is arranged downstream of the first filter plate 51 and is relatively fixed in the powder chamber 20. At the same time, the second filter holes 50 on the second filter plate 52 are circular and are evenly 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 and are integrally in a spiral blade shape, and the spiral direction is the same as that of the first blade 211.

[0046] The above-mentioned protective cylinder 6 is sleeved on the outer periphery of the powder cylinder 2 and extends along the first axial direction. The inner peripheral wall of the protective cylinder 6 faces the outer peripheral wall of the powder cylinder 2 and forms an annular protective chamber 60. The end of the protective chamber 60 close to the gas inlet 1a is provided with a protective gas inlet 60a for inputting protective gas, and the end of the protective chamber 60 close to the gas outlet 1b is provided with a protective gas outlet 60b for outputting protective gas. The protective gas outlet 60b is located outside the powder outlet 2b of the above-mentioned powder chamber 20. Similarly, the protective cylinder 6 is composed of two parts corresponding to the upstream part 23 and the downstream part 24 in the first axial direction, and the connection method is a threaded connection.

[0047] In this embodiment, the acceleration process of the gas is as follows: 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 speed of sound at the throat between the contraction section 12 and the expansion section 13 of the nozzle 1, then diffuses in the expansion section 13 until it is accelerated to supersonic speed, mixes with the powder in the filter cartridge 3 at the gas outlet 1b, and then is ejected from the spray gun.

[0048] The conveying process of the powder is as follows: The conveying of the powder is completed in the powder chamber 20. When the 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 blades 221. Since the rotation directions of the second blades 221 and the first blades 211 are opposite, when the roller 4 rotates clockwise, the first blades 211 in the roller 4 will drive the powder to rotate counterclockwise. When the rotation speed reaches a certain value, the powder will be pumped out of the roller 4 under the action of centrifugal force and the first blades 211, and reach the downstream part 24 of the powder chamber 20 through the filter plate 5.

[0049] When the external gas reaches the contraction section 12 of the nozzle 1, according to the law of conservation of energy, it can be known that in the nozzle 1, the pressure P, density ρ, and temperature T of the gas are all continuously decreasing, and the velocity V is continuously increasing. That is, the air flow experiences a decompression, cooling, and acceleration expansion process in the nozzle 1. Therefore, when the air flow reaches the end of the expansion section 13, assuming 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 the two. According to Bernoulli's equation:

[0050]

[0051] It can be seen that under the different pressures at both ends, the gas will flow from the place with higher pressure to the place with lower pressure. Therefore, in the powder chamber 20, the gas is further accelerated. In addition, due to the action of the second blades 221 on the roller 4, the gas in the powder chamber 20 will push the powder to move forward in a spiral direction. Since the particle size of the powder is small, it will move in a spiral with the gas. The advantage of this movement method is that the powder can pass through the filter cartridge 3 more evenly, reducing the risk of powder blockage caused by the powder depositing downward under the action of gravity. Finally, the powder is mixed with the supersonic gas through the filter cartridge 3.

[0052] The process of restricting the air flow is as follows: The external gas enters the protection chamber 60 through the protection gas inlet 60a, and then is discharged from the protection gas outlet 60b. The discharged protection gas to a certain extent prevents the diffusion of the gas-solid mixture ejected from the powder outlet 2b, making the mixture spray out of the muzzle relatively concentrated, thereby improving the spraying accuracy.

Claims

1. A cold spray gun, comprising: A nozzle (1) having a gas inlet (1a) and a gas outlet (1b). Along the gas flow direction, the gas inlet (1a) is located upstream of the gas outlet (1b), and the length direction of the nozzle (1) is defined as the first axial direction, and the direction around the first axial direction is the first circumferential direction; A powder cartridge (2) sleeved on the outer periphery of the side wall of the nozzle (1) and extending along the first axial direction. An annular powder chamber (20) is formed between the inner peripheral wall of the powder cartridge (2) and the side wall of the nozzle (1), and a powder outlet (2b) is provided at the end of the powder cartridge (2) close to the gas outlet (1b); It is characterized in that: Along the gas flow direction, the powder outlet (2b) is located downstream of the gas outlet (1b) of the nozzle (1) and is opposite to the gas outlet (1b); The cold spray gun further comprises: A filter cartridge (3) provided between the powder outlet (2b) of the powder cartridge (2) and the gas outlet (1b) of the nozzle (1) and extending along the first axial direction. The first end of the filter cartridge (3) is opposite to and communicated with the gas outlet (1b) of the nozzle (1), the second end of the filter cartridge (3) is opposite to and communicated with the powder outlet (2b) of the powder cartridge (2), the barrel wall of the filter cartridge (3) is opposite to the powder chamber (20), and a plurality of first filter holes (30) penetrating through the wall thickness are distributed at intervals on the barrel wall of the filter cartridge (3), so that the powder in the powder chamber (20) can enter the filter cartridge (3) through the first filter holes (30).

2. The cold spray gun according to claim 1, characterized in that: The first filter holes (30) are evenly distributed on the barrel wall of the filter cartridge (3).

3. The cold spray gun according to claim 1, wherein: The diameter of the powder outlet (2b) of the powder cartridge (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 greater than the diameter of the powder outlet (2b) of the powder cartridge (2).

4. The cold spraying gun according to any one of claims 1 to 3, characterized in that: It further comprises a roller (4) extending along the first axial direction, sleeved on the outer periphery of the side wall of the nozzle (1) in a manner that can rotate along the first circumferential direction, and located in the powder chamber (20), dividing the powder chamber (20) into an annular first chamber (21) located outside the side wall of the nozzle (1) and inside the roller (4) and an annular second chamber (22) located outside the roller (4). A gas inlet (22a) is provided at the end of the second chamber (22) close to the gas inlet (1a); A second blade (221) connected to the roller (4) and spirally extending along the outer peripheral wall of the roller (4) in the first axial direction is provided in the second chamber (22), and the second blade (221) is arranged to drive the roller (4) to rotate under the action of the airflow input from the gas inlet (22a); At the same time, a first blade (211) spirally extending along the side wall of the nozzle (1) in the first axial direction is provided in the first chamber (21). In the state where the roller (4) rotates, the first blade (211) is arranged to drive the powder in the first chamber (21) to flow towards the powder outlet (2b).

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

6. The cold spray gun according to claim 4, characterized in that: The end of the first chamber (21) near the powder outlet (2b) is provided with a filter plate (5). The plate surface of the filter plate (5) faces the first chamber (21), and a plurality of second filter holes (50) penetrating the plate thickness are distributed at intervals.

7. The cold spray gun according to claim 6, characterized in that: There are at least two filter plates (5), namely a first filter plate (51) and a second filter plate (52). Their plate surfaces face each other and are arranged along the first axial direction. The first filter plate (51) is connected to the drum (4) and can rotate with the drum (4). The second filter plate (52) is arranged downstream of the first filter plate (51) and is relatively fixed in the powder chamber (20).

8. The cold spray gun according to claim 7, characterized in that: The second filter holes (50) on the second filter plate (52) are circular and are evenly 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 and are integrally in the shape of a spiral blade, and the spiral direction is the same as that of the first blade.

9. The cold spray gun according to claim 4, characterized in that: Along the gas flow direction, the nozzle (1) has a sequentially connected intake section (11), a contraction section (12), and an expansion section (13). The intake section (11) extends along the first axial direction, and the port of the intake section (11) is the gas inlet (1a) of the nozzle (1). The flow area of the cross-section of the contraction section (12) gradually decreases along the gas flow direction, and the flow area of the cross-section of the expansion section (13) gradually increases along the gas flow direction. The port of the expansion section (13) is the gas outlet (1b) of the nozzle (1). Along the powder flow direction, the powder chamber (20) has a sequentially connected upstream part (23) and a downstream part (24). The upstream part (23) is arranged corresponding to the intake section (11) of the nozzle (1) for the drum (4) to be arranged therein, and the downstream part (24) is arranged corresponding to the contraction section (12) and the expansion section (13) of the nozzle (1).

10. The cold spray gun according to any one of claims 1 to 3, characterized in that: It further includes a protection cylinder (6) sleeved on the outer periphery of the powder cylinder (2) and extending along the first axial direction. The inner peripheral wall of the protection cylinder (6) faces the outer peripheral wall of the powder cylinder (2) and forms an annular protection chamber (60). The end of the protection chamber (60) near the gas inlet (1a) is provided with a protection gas inlet (60a) for inputting protection gas, and the end of the protection chamber (60) near the gas outlet (1b) is provided with a protection gas outlet (60b) for outputting protection gas. The protection gas outlet (60b) is located outside the powder outlet (2b) of the powder chamber (20).

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