Laser cladding powder feeding device and method applied to gradient coating

Abstract

The invention discloses a laser cladding powder feeding device and method applied to a gradient coating. The laser cladding powder feeding device comprises a laser, a powder feeding system, a filtering system, a powder weighing and recycling system, a powder mixing system and a protective gas powder supply system. Compared with the prior art, the device has the advantages that 1, the device is convenient to use and mount, powder in a proper particle size range can be screened out by changing the specification of a filter screen in the double-layer filter plate, meanwhile, the weight of the powder is monitored in real time through the powder weighing and recycling system, and the mass ratio of different powder in mixed powder is further controlled; the proportioning process of powder with different masses and particle sizes is comprehensively realized, and the powder supply continuity and stability of the powder with different masses and particle sizes in the gradient coating laser cladding process are ensured; and 2, uniform mixing and stirring of powder with different mass and particle size ratios or recovery and cyclic utilization of the same type of powder are realized, the initial powder capital cost is reduced, and sustainable utilization of the powder is promoted.

Description

Technical Field

[0001] The invention relates to the technical field of laser cladding, and in particular to a laser cladding powder feeding device and method applied to gradient coating. Background Art

[0002] Laser cladding is an efficient and precise surface treatment technology, which is widely used in the manufacturing industry. It has important application potential, especially in the surface repair and enhancement of complex shapes and high-performance materials. The powder feeding device is an important part of the laser cladding system. Its powder feeding quality directly affects the quality of the cladding layer. In order to meet the complex requirements of special workpieces for material properties, the laser cladding technology of gradient materials came into being. By adjusting the composition of the material layer by layer, the gradient change of coating performance can be achieved. The current laser cladding powder feeding equipment cannot accurately control the mass fraction and particle size range of different powder components. The manufacture of gradient coatings requires manual powder mixing and pouring into the powder barrel. After each layer of coating is completed, the powder ratio must be readjusted before the next layer of cladding can be carried out. This method leads to the discontinuity of the laser cladding process, affecting the quality and efficiency of the gradient coating. Since the powder mixing and powder feeding process of each layer are completed by manual operation, it is easy to cause inconsistency in the physical and chemical properties between coatings, which in turn affects the performance of the final product. In addition, manual operation brings greater labor intensity and unstable factors, which is difficult to adapt to the needs of large-scale industrial production.

[0003] At present, there are two main methods for laser cladding technology of gradient composite coatings: pre-setting method and single-channel synchronous powder feeding method. The pre-setting method forms a gradually changing gradient coating by changing the composition and particle size ratio of the pre-set powder layer by layer, but due to the limitations of this method in powder quality and particle size ratio, the working efficiency is low. The single-channel synchronous powder feeding method relies on mechanically mixed powders, and realizes layer-by-layer cladding of gradient composite layers by adjusting the composition and particle size ratio of the powders. However, the powder feeding system of this method is limited to single-channel powder feeding. When the powder is replaced, it may cause cross-contamination of different material components, resulting in poor powder transportation stability. Therefore, in order to ensure the continuity and stability of the powder supply of powders with different mass and particle size ratios during the laser cladding process of the gradient coating, it is necessary to design a laser cladding powder feeding device and method for gradient coating to solve the problem of discontinuous and unstable powder supply of powders with different mass and particle size ratios during the laser cladding process of the gradient coating. A weight sensor is used to implement feedback to adjust the powder feeding amount of the powder feeding system, and the mass fraction of different powders in the mixed powder is accurately controlled. By using a double-layer filter to screen powder particles that meet the particle size range, a higher-quality multi-layer coating with gradient mass and particle size changes is finally produced. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a laser cladding powder feeding device and method for gradient coating in view of the deficiencies mentioned in the above background technology.

[0005] In order to achieve the above-mentioned objectives, an embodiment of the present invention provides a laser cladding powder feeding device for gradient coating, comprising a laser, including: a powder feeding system for providing different types of powders, a filtering system for screening powders in different particle size ranges, a powder weighing and recovery system for recycling unused powders and weighing powders to be used, a powder mixing system for uniformly mixing different types of powder flows and a protective gas powder supply system for providing a powder carrier gas, the output end of the powder feeding system is connected to the input end of the filtering system, the output end of the filtering system is respectively connected to the input end of the powder weighing and recovery system and the input end of the powder mixing system, the output end of the powder mixing system is connected to the input end of the protective gas powder supply system, and the output end of the protective gas powder supply system is connected to the laser.

[0006] Furthermore, the powder delivery system comprises a first powder delivery pipe, a second powder delivery pipe and a third powder delivery pipe extending into the filtering system, and the ends of the first powder delivery pipe, the second powder delivery pipe and the third powder delivery pipe are all connected with a first material valve.

[0007] Furthermore, the filtering system includes an outer cylinder, a central axis is connected in the middle of the outer cylinder, a vertical partition plate is connected between the central axis and the outer cylinder to divide the interior of the outer cylinder into three uniform sub-areas, the sub-areas include a first area, a second area and a third area, the first powder delivery pipe, the second powder delivery pipe and the third powder delivery pipe are respectively extended to the first area, the second area and the third area, a first filter frame and a second filter frame are connected from top to bottom inside the outer cylinder, the first filter frame is located in the first area, the second area and the third area, and the first filter frame is respectively hinged with a first filter screen, a second filter screen and a third filter screen, the second filter frame is located in the first area and is set to a non-filter structure, and is located in the second area and the third area, respectively. An electric push rod is hinged inside the outer cylinder to cooperate with the first filter screen, the second filter screen, the third filter screen, the fourth filter screen and the fifth filter screen, the power end of the electric push rod is hinged to the bottom of the first filter screen, the second filter screen, the third filter screen, the fourth filter screen and the fifth filter screen, and a material receiving pipe is connected below the first area, the second area and the third area.

[0008] Furthermore, the bottoms of the first filter screen, the second filter screen, the third filter screen, the fourth filter screen and the fifth filter screen are all connected with a vibrator.

[0009] Furthermore, the powder weighing and recycling system comprises a first weighing tank, a second weighing tank and a third weighing tank, the tops of the first weighing tank, the second weighing tank and the third weighing tank are all connected with a first material guide pipe, the bottom of the material connecting pipe is connected with a recovery box, both ends of the recovery box are connected with a negative pressure extraction pipe and an air intake valve pipe, the negative pressure extraction pipe is connected with a second material valve, the bottom of the recovery box is connected with a third material valve, the bottom of the third material valve is connected with a first material delivery hose connected with the first material guide pipe, the bottoms of the first weighing tank, the second weighing tank and the third weighing tank are all connected with a second material guide pipe, the second material guide pipe is connected with a fourth material valve, the bottom of the second material guide pipe is connected with a second material delivery hose, the bottom of the second delivery hose is connected with a third material guide pipe connected with a powder mixing system, and the bottoms of the first weighing tank, the second weighing tank and the third weighing tank are all connected with a weigher.

[0010] Furthermore, the powder mixing system includes a spherical agitator, the top of the spherical agitator is connected to a stirring motor, the bottom power end of the stirring motor is connected to a stirring paddle extending into the spherical agitator, the bottom of the spherical agitator is connected to a discharge pipe connected to a protective gas powder supply system, and the discharge pipe is connected to a fifth material valve.

[0011] Furthermore, the protective gas powder supply system includes a feeding box, one end of which is connected to a fourth material guide pipe connected to the laser, and one end of the fourth material guide pipe of the feeding box is connected to a protective gas input pipe.

[0012] The present application also provides a method for feeding powder for laser cladding applied to gradient coating, which is used for the aforementioned laser cladding powder feeding device applied to gradient coating, and considers the powder feeding process of three powder mixing ratios. The specific implementation steps are as follows:

[0013] Step 1: Determine the mass fraction and particle size range of the three powders required for each layer of the gradient coating laser cladding process. That is, based on the requirements of gradient coating laser cladding, determine the particle size range and mass fraction of the three powders required for each layer of coating;

[0014] Step 2: Select the filter screen with the corresponding particle size range for the filtration system and install it. After the three powders are dried, they are sent into the filtration system through the powder feeding system to filter the three powders into different particle sizes and transport them into the powder weighing and recovery system. The powders with composite conditions are stored and weighed. The powders with different particle sizes are mixed and stirred according to the mass fraction of the coating layer to be coated, and the powder feeding is completed in conjunction with the protective gas powder supply system; the powders without composite adjustment are recycled and filtered;

[0015] Step 3: The three powders flow into the spherical agitator in a preset ratio for uniform mixing and stirring. The protective gas powder supply system is used to safely deliver the mixed powder in the spherical agitator to the laser to complete the first layer of powder delivery operation. The remaining two layers of powder delivery operations are similar.

[0016] Furthermore, the three powders include powder 1, powder 2 and powder 3, the particle size of powder 1 is n, the particle size of powder 2 is p, and the particle size range of p is p. 1 -p 2 , the particle size of powder 3 is q, and the particle size range of q is q 1 -q 2 , where n>p>q, and n, p, and q are all positive numbers;

[0017] Furthermore, when the particle size of powder 1 is n, the aperture of the first filter is larger than n. When the particle size of powder 2 is p 1 -p 2 When the aperture of the second filter is larger than p 2 Set the fourth filter screen aperture to be smaller than p 1 When the particle size range of powder 3 is q 1 -q 2 When the aperture of the third filter is larger than q 2 Set the fifth filter screen aperture to be smaller than q 1 set up.

[0018] The above scheme of the present invention has the following beneficial effects:

[0019] 1. The present invention is easy to use and install. By changing the filter screen specifications in the double-layer filter plate, powders with a suitable particle size range can be screened out. At the same time, the powder weight is monitored in real time through the powder weighing and recovery system, and the mass ratio of different powders in the mixed powder is further controlled. The process of mixing powders of different masses and particle sizes is comprehensively realized, and the powder supply continuity and stability of powders of different masses and particle sizes in the gradient coating laser cladding process are ensured, and the powder feeding efficiency in the gradient coating manufacturing process is improved;

[0020] 2. The present invention realizes the uniform mixing and stirring of powders of different mass and particle size ratios or the recovery and recycling of powders of the same type, which is beneficial to reducing the initial powder capital cost and promoting the sustainable utilization of powders.

[0021] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention is a first structural schematic diagram of a laser cladding powder feeding device applied to gradient coating.

[0023] Figure 2The second structural schematic diagram is a laser cladding powder feeding device applied to gradient coating.

[0024] Figure 3 The present invention is a schematic diagram of the cross-sectional structure of a filtering system of a laser cladding powder feeding device applied to gradient coatings.

[0025] Figure 4 The present invention is a schematic diagram of the first top cross-sectional structure of a filtering system of a laser cladding powder feeding device applied to gradient coatings.

[0026] Figure 5 The present invention is a schematic diagram of the second top view structure of a filtering system of a laser cladding powder feeding device applied to gradient coating.

[0027] Figure 6 The present invention is a schematic diagram of the structure of a powder weighing and recovery system of a laser cladding powder feeding device applied to gradient coatings.

[0028] Figure 7 The schematic diagram of the powder mixing system structure of a laser cladding powder feeding device applied to gradient coating.

[0029] [Description of Reference Numerals]

[0030] As shown in the figure: 1. Powder feeding system; 101. First powder feeding pipe; 102. Second powder feeding pipe; 103. Third powder feeding pipe; 104. First material valve; 2. Filter system; 201. Vertical partition plate; 202. First area; 203. Second area; 204. Third area; 205. First filter frame; 206. First filter screen; 207. Second filter screen; 208. Third filter screen; 209. Second filter frame; 210. No filter screen structure; 211. Fourth filter screen; 212. Fifth filter screen; 213. Electric push rod; 214. Material receiving pipe; 215. Outer cylinder; 216. Middle shaft; 217. Vibrator; 3. Powder weighing and recovery system; 301. First weighing tank; 302, second weighing tank; 303, third weighing tank; 304, recovery box; 305, negative pressure extraction pipe; 306, second material valve; 307, air inlet valve pipe; 308, third material valve; 309, first feed hose; 310, first material guide pipe; 311, second material guide pipe; 312, fourth material valve; 313, second feed hose; 314, third material guide pipe; 315, weigher; 4, powder mixing system; 401, stirring motor; 402, stirring paddle; 403, discharge pipe; 404, fifth material valve; 405, spherical agitator; 5, protective gas powder supply system; 501, feeding box; 502, protective gas input pipe; 503, fourth material guide pipe; 6, laser. DETAILED DESCRIPTION

[0031] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0032] Combined with Figure 1-7 A laser cladding powder feeding device for gradient coating includes a laser 6, a powder feeding system 1 for providing different types of powders, a filtering system 2 for screening powders in different particle size ranges, a powder weighing and recovery system 3 for recycling unused powders and weighing powders to be used, a powder mixing system 4 for uniformly mixing different types of powder flows and a protective gas powder supply system 5 for providing a powder carrier gas, wherein the output end of the powder feeding system 1 is connected to the input end of the filtering system 2, the output end of the filtering system 2 is respectively connected to the input end of the powder weighing and recovery system 3 and the input end of the powder mixing system 4, the output end of the powder mixing system 4 is connected to the input end of the protective gas powder supply system 5, and the output end of the protective gas powder supply system 5 is connected to the laser 6.

[0033] The powder delivery system 1 comprises a first powder delivery pipe 101 , a second powder delivery pipe 102 and a third powder delivery pipe 103 extending into the filtering system 2 , and the ends of the first powder delivery pipe 101 , the second powder delivery pipe 102 and the third powder delivery pipe 103 are all connected with a first material valve 104 .

[0034] The filtration system 2 comprises an outer cylinder 215, wherein a central axis 216 is connected in the middle of the outer cylinder 215, and a vertical partition plate 201 is connected between the central axis 216 and the outer cylinder 215 to divide the inner part of the outer cylinder 215 into three uniform sub-areas, wherein the sub-areas comprise a first area 202, a second area 203 and a third area 204, and a first filter frame 205 and a second filter frame 209 are connected from top to bottom inside the outer cylinder 215, wherein the first filter frame 205 is located in the first area 202, the second area 203 and the third area 204 and is respectively hinged with a first filter screen 206, a second filter screen 207 and a third filter screen 208, and the second filter frame 205 is ... 09 The first area 202 is set as a filter-free structure 210, and the second area 203 and the third area 204 are respectively hinged with a fourth filter 211 and a fifth filter 212, and the outer cylinder 215 is hingedly provided with an electric push rod 213 for matching the first filter 206, the second filter 207, the third filter 208, the fourth filter 211 and the fifth filter 212. The power end of the electric push rod 213 is hingedly set to the bottom of the first filter 206, the second filter 207, the third filter 208, the fourth filter 211 and the fifth filter 212, and a material receiving pipe 214 is connected to the bottom of the first area 202, the second area 203 and the third area 204.

[0035] The bottoms of the first filter screen 206 , the second filter screen 207 , the third filter screen 208 , the fourth filter screen 211 and the fifth filter screen 212 are all connected with a vibrator 217 .

[0036] The powder weighing and recycling system 3 comprises a first weighing tank 301, a second weighing tank 302 and a third weighing tank 303. The tops of the first weighing tank 301, the second weighing tank 302 and the third weighing tank 303 are all connected with a first material guide pipe 310. The bottom of the material receiving pipe 214 is connected with a recovery box 304. Both ends of the recovery box 304 are connected with a negative pressure extraction pipe 305 and an air intake valve pipe 307. The negative pressure extraction pipe 305 often needs to be connected to the powder feeding system 1 to facilitate material recycling. The air intake valve pipe 307 adopts a one-way valve to facilitate the negative pressure extraction operation. The negative pressure extraction pipe 305 is connected with a second material valve 306. The recovery box 3 04 is connected to a third material valve 308 at the bottom, and a first material delivery hose 309 connected to the first material guide pipe 310 is connected to the bottom of the third material valve 308; a second material guide pipe 311 is connected to the bottom of the first weighing tank 301, the second weighing tank 302 and the third weighing tank 303; a fourth material valve 312 is connected to the second material guide pipe 311; a second material delivery hose 313 is connected to the bottom of the second material guide pipe 311; a third material guide pipe 314 connected to the powder mixing system 4 is connected to the bottom of the second material delivery hose 313; a weigher 315 is connected to the bottom of the first weighing tank 301, the second weighing tank 302 and the third weighing tank 303.

[0037] The powder mixing system 4 includes a spherical agitator 405, the top of the spherical agitator 405 is connected to a stirring motor 401, the bottom power end of the stirring motor 401 is connected to a stirring paddle 402 extending into the spherical agitator 405, the bottom of the spherical agitator 405 is connected to a discharge pipe 403 connected to the protective gas powder supply system 5, and the discharge pipe 403 is connected to a fifth material valve 404.

[0038] The protective gas powder supply system 5 includes a feeding box 501, one end of which is connected to a fourth material guide pipe 503 connected to the laser 6, and one end of the fourth material guide pipe 503 of the feeding box 501 is connected to a protective gas input pipe 502, and the protective gas used is argon. Specific embodiment:

[0040] Considering the powder feeding process of three powders mixed ratio, the specific implementation steps are as follows: Step 1: Determine the mass fraction and particle size range of the three powders required layer by layer during the gradient coating laser cladding process, that is, the three powders include powder 1, powder 2 and powder 3, the particle size of powder 1 is n, the particle size of powder 2 is p, and the particle size range of p is p1 -p 2 , the particle size of powder 3 is q, and the particle size range of q is q 1 -q 2 , where n>p>q, and n, p, q are all positive numbers, p 2 >p 1 ,q 2 >q 1 ,

[0041] When the particle size of powder 1 is greater than n, the aperture of the first filter (206) is greater than n. When the particle size of powder 2 is in the range of p 1 -p 2 When the aperture of the second filter (207) is larger than p 2 The aperture of the fourth filter (211) is smaller than p 1 , when the particle size range of powder 3 is q 1 -q 2 When the aperture of the third filter screen (208) is larger than q 2 The aperture of the fifth filter (212) is smaller than q 1 ;

[0042] Take the three-layer gradient coating as an example, where the particle size of powder 1 is greater than 50nm, the particle size of powder 2 is 10-20nm, and the particle size of powder 3 is 5-10nm:

[0043] When the particle size of powder 1 is greater than 50 nm, the aperture of the first filter (206) is greater than 50 nm. When the particle size of powder 2 is in the range of 10-20 nm (i.e., 1 =10, p 2 =20), the aperture of the second filter (207) is set to be larger than 20 nm, and the aperture of the fourth filter (211) is set to be smaller than 10 nm. When the particle size of the powder 3 is in the range of 5-10 nm (i.e., q 1 =5,q 2 =10), the aperture of the third filter (208) is set to be larger than 10 nm, and the aperture of the fifth filter (212) is set to be smaller than 5 mm;

[0044] The mass fractions of the mixed powders in the first layer are 80% for powder 1, 10% for powder 2, and 10% for powder 3; the mass fractions of the mixed powders in the second layer are 65% for powder 1, 20% for powder 2, and 15% for powder 3; the mass fractions of the mixed powders in the third layer are 50% for powder 1, 30% for powder 2, and 20% for powder 3;

[0045] Step 2: After being dried, the powder 1 enters the first area 202 through the first powder delivery pipe 101 and the first material valve 104, and is filtered through the first filter screen 206 (the powder particle size is allowed to pass through 50nm or less), and then flows through the filter-free structure 210 to reach the material receiving pipe 214, and then reaches the recovery box 304 through the material receiving pipe 214. The materials with a powder particle size of less than 50nm are extracted and recovered through the negative pressure extraction pipe 305 and the air intake valve pipe 307 for recycling. After the recycling is completed, the second material valve 306 is closed, the third material valve 308 is started, and the electric push rod 213 corresponding to the first filter screen 206 is started to drive the first filter screen 206 to turn down, and the powder 1 with a particle size range greater than 50nm falls into the first weighing tank 301;

[0046] After being dried, the powder 2 enters the second area 203 through the second powder delivery pipe 102 and the first material valve 104, is filtered through the second filter 207 (the powder particle size is allowed to pass through the value of 20nm or less), and then is filtered through the fourth filter 211 below (the powder particle size is allowed to pass through the value of 10nm or less), and then reaches the receiving pipe 214, and then reaches the recovery box 304 through the receiving pipe 214. The powder material with a particle size of less than 10nm is extracted and recycled through the negative pressure extraction pipe 305 and the intake valve pipe 307 for recycling. After the recycling is completed, the second material valve 306 is closed. The third material valve 308 is started, and the electric push rod 213 corresponding to the fourth filter 211 is started to drive the fourth filter 211 to turn down, so that the powder 2 with a particle size range of 10-20nm falls into the second weighing tank 302, and then the third material valve 308 is closed, and the electric push rod 213 corresponding to the second filter 207 is started to drive the second filter 207 to turn down, so that the powder 2 with a particle size range greater than 20mm reaches the recovery box 304 through the material receiving pipe 214, and the powder material with a particle size greater than 20nm is extracted and recycled through the negative pressure extraction pipe 305 and the air intake valve pipe 307 for recycling;

[0047] After being dried, the powder 3 enters the third area 204 through the third powder delivery pipe 103 and the first material valve 104, is filtered through the third filter screen 208 (the powder particle size is allowed to pass through a value of less than 10nm), and then is filtered through the fifth filter screen 212 below (the powder particle size is allowed to pass through a value of less than 5nm), and then reaches the material receiving pipe 214, and then reaches the recovery box 304 through the material receiving pipe 214. The powder material with a particle size of less than 5nm is extracted and recycled through the negative pressure extraction pipe 305 and the intake valve pipe 307 for recycling. After the recycling is completed, the second material valve 306 is closed and the start The third material valve 308 is activated, and the electric push rod 213 corresponding to the fifth filter screen 212 is started to drive the fifth filter screen 212 to flip down, so that the powder 3 with a particle size range of 5-10nm falls into the third weighing tank 303, and then the third material valve 308 is closed, and the electric push rod 213 corresponding to the third filter screen 208 is started to drive the second filter screen 207 to flip down, so that the powder 3 with a particle size range greater than 10mm reaches the recovery box 304 through the material receiving pipe 214, and the powder material with a particle size greater than 10nm is extracted and recycled through the negative pressure extraction pipe 305 and the air intake valve pipe 307 for recycling;

[0048] The first weighing tank 301, the second weighing tank 302 and the third weighing tank 303 sense the internal weight through the scale 315, and then transport three powders with different particle diameters and weights into the spherical agitator 405 according to the weight difference. When the three powders with different particle diameters and weights are transported into the spherical agitator 405, the filtering and weighing process above is stopped. After the powder transporting operation into the spherical agitator 405 is completed, the filtering, recycling and weighing work above are continued, so that the first weighing tank 301, the second weighing tank 302 and the third weighing tank 303 are all set with a certain weight range, that is, the filtering operation is stopped when the internal weight is higher than a certain value, and the filtering operation is started when the internal weight is lower than a certain value.

[0049] Step 3: The three powders flow into the spherical agitator 405 for uniform mixing and stirring. The protective gas powder supply system 5 cooperates with the mixed powder in the spherical agitator 405 to be safely delivered to the laser 6 to complete the first layer of powder delivery operation. The remaining two layers of powder delivery operations are similar.

[0050] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A laser cladding powder feeding device for gradient coating, comprising a laser (6), characterized in that: include: A powder delivery system (1) for providing different types of powders, a filtering system (2) for screening powders in different particle size ranges, a powder weighing and recycling system (3) for recycling unused powders and weighing powders to be used, a powder mixing system (4) for uniformly mixing different types of powder flows, and a protective gas powder supply system (5) for providing a powder carrier gas, wherein the output end of the powder delivery system (1) is connected to the input end of the filtering system (2), the output end of the filtering system (2) is respectively connected to the input end of the powder weighing and recycling system (3) and the input end of the powder mixing system (4), the output end of the powder mixing system (4) is connected to the input end of the protective gas powder supply system (5), and the output end of the protective gas powder supply system (5) is connected to a laser (6).

2. The laser cladding powder feeding device for gradient coating according to claim 1 is characterized in that: The powder delivery system (1) comprises a first powder delivery pipe (101), a second powder delivery pipe (102) and a third powder delivery pipe (103) extending into the filtering system (2); the ends of the first powder delivery pipe (101), the second powder delivery pipe (102) and the third powder delivery pipe (103) are all connected to a first material valve (104).

3. The laser cladding powder feeding device for gradient coating according to claim 2 is characterized in that: The filtering system (2) comprises an outer cylinder (215), a central axis (216) is connected in the middle of the outer cylinder (215), a vertical partition plate (201) is connected between the central axis (216) and the outer cylinder (215) to divide the inner part of the outer cylinder (215) into three uniform sub-areas, the sub-areas comprising a first area (202), a second area (203) and a third area (204), the first powder delivery pipe (101), the second powder delivery pipe (102) and the third powder delivery pipe (103) are respectively extended to the first area (202), the second area (203) and the third area (204) to be arranged, the inner part of the outer cylinder (215) is connected from top to bottom with a first filter frame (205) and a second filter frame (209), the first filter frame (205) is located in the first area (202), the second area (203) and the third area (204) and is respectively hinged with a first filter screen (206) ), a second filter screen (207) and a third filter screen (208); the second filter frame (209) is located in the first area (202) and is set as a filter-free structure (210); a fourth filter screen (211) and a fifth filter screen (212) are respectively hingedly provided in the second area (203) and the third area (204); an electric push rod (213) is hingedly provided inside the outer cylinder (215) to cooperate with the first filter screen (206), the second filter screen (207), the third filter screen (208), the fourth filter screen (211) and the fifth filter screen (212); a power end of the electric push rod (213) is hingedly provided with the bottom of the first filter screen (206), the second filter screen (207), the third filter screen (208), the fourth filter screen (211) and the fifth filter screen (212); and a material receiving pipe (214) is connected below the first area (202), the second area (203) and the third area (204).

4. The laser cladding powder feeding device for gradient coating according to claim 3 is characterized in that: The bottoms of the first filter screen (206), the second filter screen (207), the third filter screen (208), the fourth filter screen (211) and the fifth filter screen (212) are all connected with a vibrator (217).

5. The laser cladding powder feeding device for gradient coating according to claim 3 is characterized in that: The powder weighing and recycling system (3) comprises a first weighing tank (301), a second weighing tank (302) and a third weighing tank (303), wherein the tops of the first weighing tank (301), the second weighing tank (302) and the third weighing tank (303) are all connected with a first material guide pipe (310), the bottom of the material receiving pipe (214) is connected with a recycling box (304), both ends of the recycling box (304) are connected with a negative pressure extraction pipe (305) and an air intake valve pipe (307), the negative pressure extraction pipe (305) is connected with a second material valve (306), the bottom of the recycling box (304) is connected with a third material valve (308), and the bottom of the third material valve (308) is connected with a A first material delivery hose (309) connected to the first material guide pipe (310) is connected; the first weighing tank (301), the second weighing tank (302) and the third weighing tank (303) are all connected to the bottom with a second material guide pipe (311); a fourth material valve (312) is connected to the second material guide pipe (311); a second material delivery hose (313) is connected to the bottom of the second material guide pipe (311); a third material delivery hose (314) connected to the powder mixing system (4) is connected to the bottom of the second material delivery hose (313); and a weighing device (315) is connected to the bottom of the first weighing tank (301), the second weighing tank (302) and the third weighing tank (303).

6. The laser cladding powder feeding device for gradient coating according to claim 1, characterized in that: The powder mixing system (4) comprises a spherical agitator (405), the top of the spherical agitator (405) is connected to a stirring motor (401), the bottom power end of the stirring motor (401) is connected to a stirring paddle (402) extending into the spherical agitator (405), the bottom of the spherical agitator (405) is connected to a discharge pipe (403) connected to a protective gas powder supply system (5), and the discharge pipe (403) is connected to a fifth material valve (404).

7. The laser cladding powder feeding device for gradient coating according to claim 1 is characterized in that: The protective gas powder supply system (5) comprises a feeding box (501), one end of which is connected to a fourth material guide pipe (503) connected to a laser (6), and one end of which is connected to a protective gas input pipe (502).

8. A method for feeding powder for laser cladding of gradient coating, used in a laser cladding powder feeding device for gradient coating according to any one of claims 1 to 7, characterized in that: Considering the powder feeding process of three kinds of powder mixing ratio, the specific implementation steps are as follows: Step 1: Determine the mass fraction and particle size range of the three powders required for each layer of the gradient coating laser cladding process. That is, based on the requirements of gradient coating laser cladding, determine the particle size range and mass fraction of the three powders required for each layer of coating; Step 2: Select a filter screen with a corresponding particle size range for the filtration system (2) and install it. After the three powders are dried, they are sent to the filtration system (2) through the powder feeding system (1). The three powders are filtered into different particle sizes and sent to the powder weighing and recovery system (3). The powders with composite conditions are stored and weighed. The powders with different particle sizes are mixed and stirred according to the mass fraction of the coating layer to be coated, and the protective gas powder supply system is used to complete the powder feeding. The powders without composite adjustment are recovered and filtered in a cycle. Step 3: The three powders flow into the spherical agitator (405) in a preset ratio for uniform mixing and stirring. The protective gas powder supply system (5) is used to safely deliver the mixed powder in the spherical agitator (405) to the laser (6) to complete the first layer of powder delivery operation. The remaining two layers of powder delivery operations are similar.

9. The method according to claim 8, characterized in that: The three powders include powder 1, powder 2 and powder 3, the particle size of powder 1 is n, the particle size of powder 2 is p, the particle size range of p is p1-p2, the particle size of powder 3 is q, the particle size range of q is q1-q2, wherein n>p>q, and n, p, q are all positive numbers.

10. The method according to claim 9, characterized in that: When the particle size of powder 1 is n, the aperture of the first filter (206) is larger than the n setting; when the particle size range of powder 2 is p1-p2, the aperture of the second filter (207) is larger than the p2 setting, and the aperture of the fourth filter (211) is smaller than the p1 setting; when the particle size range of powder 3 is q1-q2, the aperture of the third filter (208) is larger than the q2 setting, and the aperture of the fifth filter (212) is smaller than the q1 setting.

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