Powder feeding device, spraying device and sealing modification method of light metal workpiece

Abstract

The application discloses a powder feeding device, a spraying device and a sealing modification method of a light metal workpiece, and belongs to the technical field of light metal workpiece surface protection. The powder feeding device comprises a feeding pipe, a scattering pipe and a fan. The feeding pipe is provided with a powder channel, a plasma jet channel and a protective gas channel. The scattering pipe is coaxially communicated with the discharging end. The fan is coaxially arranged in the scattering pipe and comprises a plurality of fan blades which can rotate around the rotating shaft of the fan. The plurality of fan blades are distributed along the circumference of the scattering pipe. Each of the fan blades is provided with a plurality of powder passing holes which are distributed at intervals. The central axis of the powder passing hole is inclined to the central axis of the feeding pipe. The powder feeding device has good powder feeding uniformity. The light metal workpiece to be modified has a short residence time at high temperature, and the light metal workpiece is not easy to deform.

Description

Technical Field

[0001] This invention belongs to the field of surface protection technology for light metal workpieces, specifically relating to a powder feeding device, a spraying device, and a method for sealing and modifying light metal workpieces. Background Technology

[0002] Lightweight metal parts, such as aluminum alloys and magnesium alloys, are widely used in aerospace equipment components due to their light weight, offering advantages such as energy saving, emission reduction, and cost-effectiveness. However, lightweight metal parts have varying degrees of porosity on their surfaces, leading to corrosion during service. To extend the service life of these components, a sealing process is performed to reduce the porosity of the coating and improve their overall service life.

[0003] In the prior art, patent CN108796493B discloses a method for sealing and modifying the pores of a cold-sprayed coating on the surface of a light metal workpiece. The method involves placing the cold-sprayed coated light metal workpiece in a double-glow furnace, using the glow discharge effect of a double hollow cathode to heat the workpiece and a target material of the same material as the coating. The target material is placed on a source electrode holder, and under the bombardment of plasma generated by the glow discharge, heating causes evaporation and sputtering, depositing on the workpiece surface. Due to the workpiece's heating, diffusion occurs, sealing and diffusion treatment is applied to the cold-sprayed coating, thereby eliminating pores on the coating surface and inside. This patent achieves the purpose of sealing pores by performing plasma spraying at high temperatures, causing the sprayed coating to diffuse due to heating. However, due to the different melting points of metals, some metals (mercury, francium, cesium) have lower melting points, making the metal surface prone to deformation at high temperatures. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a powder feeding device, a spraying device, and a method for sealing and modifying light metal workpieces, wherein the sealing powder is uniformly distributed on the light metal workpieces, and the light metal workpieces are not easily deformed.

[0005] One technical solution adopted by the present invention is: a powder feeding device for spraying sealing powder onto light metal workpieces, characterized in that it comprises:

[0006] The feeding tube has a feeding end and a discharging end that are arranged opposite to each other. The feeding end is provided with a powder channel, a plasma jet channel and a protective gas channel that are all connected to the inner cavity of the feeding tube.

[0007] A scattering tube is coaxially connected to the discharge end;

[0008] The fan is coaxially located inside the scattering tube and includes multiple fan blades that can rotate around the fan's axis. The multiple fan blades are distributed circumferentially along the scattering tube. Each fan blade is provided with multiple spaced powder passage holes. The central axis of the powder passage hole is inclined towards the central axis of the feeding tube at one end.

[0009] In some embodiments, in each of the fan blades, the central axis of the powder passage is inclined toward the leading edge of the fan blade near the end of the feed tube.

[0010] In some embodiments, the fan blade is curved, and the powder passage is perpendicular to the part of the fan blade where the powder passage is located.

[0011] In some embodiments, the diameter of the powder passage hole decreases sequentially from the tip of the fan blade to the root.

[0012] In some embodiments, in each of the fan blades, the density of the powder-passing holes decreases sequentially from the tip of the fan blade to the root.

[0013] In some embodiments, the gap between the tip of the fan blade and the inner wall of the scattering tube is 2mm to 4mm; the distance between the outermost powder passage of the fan and the inner wall of the scattering tube is 0.5mm to 1.5mm; and the distance between the innermost powder passage of the fan and the central axis of the scattering tube is 5mm to 15mm.

[0014] Along the direction from the feeding end to the discharging end, the radial dimension of the inner cavity of the feeding tube first decreases and then increases.

[0015] In some embodiments, the powder feeding device includes a connector that connects the scattering tube and the feeding tube.

[0016] The connector includes a rotating ball, and the inner wall of the discharge end and the outer wall of the scattering tube are both provided with mounting grooves. The gap between the rotating ball and the mounting groove of the discharge end and the scattering tube is set in the mounting groove. There are multiple connectors, and the multiple connectors are arranged radially with the axial direction of the scattering tube as the center.

[0017] In some embodiments, the radial dimension of the mounting groove of the scattering tube is the same as the radial dimension of the rotating ball, the connector further includes a fastener, the discharge end is provided with a fastening hole that penetrates the sidewall and communicates with the mounting groove, the fastener is located in the fastening hole, and the fastener is hinged to the rotating ball.

[0018] Another technical solution adopted by the present invention is to provide a spraying device, including the aforementioned powder feeding device.

[0019] Another technical solution adopted by the present invention is: a method for sealing and modifying light metal workpieces, using the aforementioned powder feeding device, wherein the sealing and modifying method includes:

[0020] Sealing powder, plasma jet, and protective gas are introduced into the feeding pipe through a powder channel, a plasma jet channel, and a protective gas channel, respectively. The plasma jet carrying the sealing powder and protective gas is sprayed from the feeding pipe into the scattering pipe. At the same time, the fan blades rotate so that the plasma jet carrying the sealing powder and protective gas is scattered and sprayed from the powder passage of the fan blades onto the surface of the light metal workpiece to be sealed and modified.

[0021] In some embodiments, during the pore-sealing modification process, the relative motion speed between the light metal workpiece to be sealed and the powder feeding device is 20-200 m / min, and the voltage of the plasma jet is 500-700 V.

[0022] In some embodiments, the light metal workpiece to be sealed and modified is located below the powder feeding device;

[0023] The process after the sealing modification includes the following steps: reducing the voltage of the plasma jet at a rate of 100V / 2h while stopping the introduction of sealing powder to cool the light metal workpiece.

[0024] The beneficial effects of the present invention include at least the following:

[0025] The powder feeding device provided in this embodiment of the invention is used to spray sealing powder onto light metal workpieces. The powder feeding device includes a feeding pipe, a scattering pipe, and a fan. The feeding pipe has a feeding end and a discharging end arranged opposite to each other. The feeding end is provided with a powder channel, a plasma jet channel, and a protective gas channel, all connected to the inner cavity of the feeding pipe. The plasma jet, protective gas, and sealing powder enter the feeding pipe through the plasma jet channel, the protective gas channel, and the powder channel, respectively. The scattering pipe is coaxially connected to the discharging end. Because the plasma jet, protective gas, and powder can move from the discharging pipe into the scattering pipe, and because the scattering pipe is equipped with a fan with multiple blades, the sealing powder will generate centrifugal motion under the action of the blades during the rotation of the fan around the axis. This causes the sealing powder to be scattered outward through the powder passage of the fan, and the scattering area is much larger than the inner diameter area of ​​the scattering pipe, thereby increasing the interaction area between the sealing powder and the light metal workpiece. This allows for a rapid completion of the sealing modification process of the light metal workpiece. Therefore, the residence time of the light metal workpiece at high temperature is short, and the light metal workpiece is not easily deformed.

[0026] In related technologies, the large size of light metal workpieces necessitates segmented powder coating, resulting in prolonged powder coating time and extended high-temperature residence time. Furthermore, segmented powder coating between metal parts can lead to overlapping coating at the boundaries of adjacent areas, resulting in poor coating uniformity. In contrast, the fan within the scattering tube of this invention allows for a large scattering area of ​​the sealing powder delivered by the powder feeding device. Even with large light metal workpieces, coating can be completed in a single pass, minimizing high-temperature residence time, increasing efficiency, and reducing the likelihood of deformation. Moreover, the elimination of segmented powder coating ensures uniform coating of the sealing powder on the light metal workpieces. Attached Figure Description

[0027] Figure 1 A schematic diagram of the powder feeding device in Embodiment 1 is shown.

[0028] Figure 2 It shows Figure 1 A schematic diagram of the fan structure in the powder feeding device.

[0029] Figure 3 A process flowchart of the sealing modification method for light metal workpieces in Example 3 is shown.

[0030] Explanation of reference numerals in the attached figures:

[0031] 10-Feeding pipe, 11-Powder channel, 12-Plasma jet channel, 13-Protective gas channel, 14-Feeding end, 15-Discharge end; 20-Scattering pipe; 30-Rotating ball; 40-Fastener; 50-Fan, 51-Fan blade. Detailed Implementation

[0032] To enable those skilled in the art to better understand this application, the technical solution of this application will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] This application provides a powder feeding device, a spraying device, and a method for sealing and modifying light metal workpieces. The powder feeding device can feed powder to light metal workpieces such as aluminum alloy workpieces and magnesium alloy workpieces that are to be coated, thereby improving the scattering area of ​​the sealing powder sprayed from the scattering tube. The coating of light metal workpieces can be completed in one spraying. The high temperature dwell time of the metal parts is short, the efficiency is high, and the metal parts are not easily deformed. Moreover, there is no need for regional spraying, which ensures the uniformity of the sealing powder coating of the light metal workpieces.

[0034] Example 1

[0035] This application provides a powder feeding device for spraying sealing powder onto light metal workpieces, which can be large-sized workpieces such as high-speed train carriages or automobile spoilers. Please refer to... Figure 1 as well as Figure 2 The powder feeding device includes a feeding pipe 10, a scattering pipe 20, and a fan. The feeding pipe 10 has a feeding end 14 and a discharging end 15 arranged opposite to each other. The feeding end 14 is provided with a powder channel 11, a plasma jet channel 12, and a protective gas channel 13, all of which are connected to the inner cavity of the feeding pipe 10. The scattering pipe 20 is coaxially connected to the discharging end 15. The fan 50 is coaxially located inside the scattering pipe 20 and includes multiple fan blades 51 that can rotate around the axis of the fan 50. The multiple fan blades 51 are distributed circumferentially along the scattering pipe 20. Each fan blade 51 is provided with multiple powder passage holes distributed at intervals. The end of the central axis of the powder passage hole near the feeding pipe 10 is inclined toward the central axis of the feeding pipe 10.

[0036] The powder channel 11 can be used to introduce sealing powder, the plasma jet channel 12 can be used to introduce plasma jet, and the protective gas channel 13 can be used to introduce protective gas, such as nitrogen or argon. The plasma jet can carry the sealing powder to the discharge end 15 and into the scattering tube 20. Since the fan 50 is located inside the heat dissipation tube, the fan 50 is equipped with rotatable fan blades 5150. During the rotation of the fan blades 51 around the axis, the sealing powder will generate centrifugal motion under the action of the fan blades 51, so that the sealing powder is scattered outward from the powder passage of the fan 50 to the scattering tube 20. The scattering area is much larger than the inner diameter area of ​​the scattering tube 20, thereby increasing the interaction area between the sealing powder and the light metal workpiece. This allows the sealing modification process of the light metal workpiece to be completed quickly. Therefore, the residence time of the light metal workpiece at high temperature is short, and the light metal workpiece is not easily deformed.

[0037] The central axis of the powder passage is inclined towards the central axis of the feeding pipe 10 at one end, which can limit the direction of scattering of the sealing powder along the powder passage to be away from the central axis of the feeding pipe 10, thereby increasing the scattering area of ​​the sealing powder after it exits the scattering pipe 20.

[0038] In some embodiments, the plasma channel, the protective gas channel 13, and the powder channel 11 can be arranged at intervals. In other embodiments, the plasma channel can be a central channel, the powder channel 11 can be encircled by the plasma channel, and the protective gas channel 13 can be encircled by the plasma channel. The three channels are arranged coaxially. In some embodiments, the powder channel 11 can also be a central channel. In other embodiments, the protective gas channel 13 can also be a central channel.

[0039] In some embodiments, in each fan blade 51, the central axis of the powder passage is inclined towards the leading edge of the fan blade 51 at the end near the feed pipe 10, so as not to reduce the running speed of the sealing powder as much as possible, and to further guide the sealing powder through the powder passage to form a large and uniform scattered powder flow with a certain speed.

[0040] In some embodiments, the powder passage hole is perpendicular to the part of the fan blade 51 where the powder passage hole is located. In other embodiments, the powder passage hole and the part of the fan blade 51 where the powder passage hole is located may also have a certain angle, such as an acute angle or an obtuse angle, which is related to the shape of the fan blade 51 itself.

[0041] In some embodiments, the diameter of the powder passage holes decreases sequentially from the tip to the root of the fan blade 51. During the process of the sealing powder entering the scattering tube 20 from the feed pipe 10, the sealing powder mainly concentrates in the central axis portion of the scattering tube 20. The size of the powder passage holes near the central axis of the scattering tube 20 is larger than that of the powder passage holes far from the central axis, which facilitates the dispersion of the sealing powder concentrated in the central axis portion to the entire scattering surface. This improves the uniformity of powder distribution on the scattering surface after the scattering tube 20, and enhances the density and uniformity of the light metal workpiece after sealing modification.

[0042] In order to further improve the density and uniformity of the light metal workpiece after the sealing modification, in some embodiments, the density of the powder passage holes in each fan blade 51 decreases sequentially from the tip to the root of the fan blade 51.

[0043] In some embodiments, the gap between the tip of the fan blade 51 and the inner wall of the scattering tube 20 is 2 mm to 4 mm; the distance between the outermost powder passage of the fan 50 and the inner wall of the scattering tube 20 is 0.5 mm to 1.5 mm; and the distance between the innermost powder passage of the fan 50 and the central axis of the scattering tube 20 is 5 mm to 15 mm, so as to further improve the uniformity and area of ​​the scattering surface of the sealing powder.

[0044] In some embodiments, the number of fan blades 51 can be 4, 5, 6, or other numbers; the distance between the fan 50 and the outlet end of the diffuser tube 20 is 5mm to 10mm; and the diameter of the diffuser tube 20 is 25mm to 35mm. In some embodiments, the leading edge of the fan blade 51 is located at the front end in the rotation direction of the fan blade 51.

[0045] The fan blade 51 can be made of polytetrafluoroethylene, which is heat-resistant and will not stick to the sealing powder.

[0046] In some embodiments, the powder feeding device also includes a motor connected to the fan 50, the motor being located inside the scattering tube 20. When selecting a motor, attention should be paid to its size; the smaller the size of the motor, the better, as a smaller motor size has less impact on the scattering flow of the sealing powder.

[0047] To increase the velocity of the plasma jet, in some embodiments, the radial dimension of the inner cavity of the feed tube 10 first decreases and then increases along the direction from the feed end 14 to the discharge end 15, forming a Venturi tube structure, which reduces the plasma jet from coarse to fine to accelerate the flow rate of the sealing powder. This creates a "vacuum" zone from the point where the radial dimension of the inner cavity is the smallest to the discharge end 15. This "vacuum" zone will adsorb the light metal workpiece to be sealed and modified, thus enabling the adsorption of powder coating.

[0048] In some embodiments, the inner cavity of the scattering tube 20 increases sequentially along the direction from the feeding end 14 to the discharging end 15, and the scattering tube 20 and the feeding tube 10 together form a venturi structure of the reflecting cavity, which is symmetrically arranged about the central plane of the central axis of the scattering tube 20.

[0049] In some embodiments, the powder feeding device includes a connector connecting the feeding pipe 10 and the scattering pipe 20. The connector includes a rotating ball 30. The inner wall of the discharge end 15 and the outer wall of the scattering pipe 20 are both provided with mounting grooves. The rotating ball 30 is spaced within the mounting grooves of the discharge end 15 and the scattering pipe 20. Multiple connectors are provided, arranged radially around the axial direction of the scattering pipe 20. Under the impact of the plasma jet, the scattering pipe 20 can rotate slightly relative to the feeding pipe 10 for buffering. The rotating ball 30 enables the scattering pipe 20 to rotate smoothly with respect to the discharge end 15. The wall of the mounting groove can be spherical or cylindrical, with the cylindrical surface parallel to the central axis of the scattering pipe 20. The feeding pipe 10 and the scattering pipe 20 are connected by the connector, facilitating processing and installation.

[0050] Specifically, in some embodiments, the rotatable connection between the scattering tube 20 and the discharge end 15 can be achieved by a slide rail slider. The inner wall of the scattering tube 20 is provided with an annular groove coaxial with the scattering tube 20, and the outer side of the discharge tube is provided with a slider, which is slidably disposed in the annular groove. In order to improve the stability of the relative rotation between the feeding tube 10 and the scattering tube 20, multiple sliders can be provided, and the multiple sliders are evenly distributed in the annular groove.

[0051] To further improve the stability of the relative rotation of the feeding pipe 10 and the scattering pipe 20, in some embodiments, multiple connectors may be provided. These connectors are arranged radially around the axial direction of the scattering pipe 20, meaning that the inner wall of the discharge end 15 and the outer wall of the scattering pipe 20 are both provided with multiple mounting grooves. The number of mounting grooves on the rotating balls 30 is the same as that on the scattering pipe 20, and each rotating ball 30 is positioned in two corresponding mounting grooves.

[0052] For ease of assembly, please combine Figure 1In some embodiments, the radial dimension of the mounting groove of the scattering tube 20 is the same as the radial dimension of the rotating ball 30. The connector also includes a fastener 40. The discharge end 15 is provided with a fastening hole that penetrates the side wall and communicates with the mounting groove. The fastener 40 is located in the fastening hole and is hinged to the rotating ball 30. During assembly, the fastener 40 can be installed in the fastening hole first, and then the fastener 40 can be hinged to the rotating ball 30. Then, the position of the fastener 40 in the fastening hole is adjusted so that the rotating ball 30 is close to the bottom of the mounting groove of the scattering tube 20. Multiple rotating balls 30 are placed in the mounting groove of the outer wall of the feeding tube 10. Then, the scattering tube 20 is sleeved on the outside of the discharge end 15. When the rotating ball 30 is aligned with the mounting groove of the scattering tube 20, the fastener 40 is rotated so that the rotating groove moves toward the axis of the scattering tube 20 until the rotating ball 30 moves to the target position, thereby completing the assembly of the scattering tube 20 and the feeding tube 10. Fastener 40 can be a screw, with the screw nut located outside the scattering tube 20 and the screw shaft hinged to the rotating ball 30.

[0053] The powder feeding device provided in this embodiment has a fan 50 at the outlet of the scattering tube 20. The fan blades 5150 of the fan 50 are rotatable and have powder passage holes, which increases the size of the scattering flow formed by the sealing powder carried by the plasma jet. Therefore, the sealing modification of the entire light metal workpiece can be achieved by spraying only once, thus improving the sealing modification efficiency. Since only one spraying is required, the light metal workpiece has a short residence time at high temperature and is not easily deformed. There is no need for multiple repeated sprayings, so there will be no missed coating or repeated spraying, thus improving the coating uniformity of the light metal workpiece.

[0054] Example 2

[0055] This application provides a spraying device, which includes a plasma emitter, a powder storage tank, a gas source, and a powder feeding device as described in Embodiment 1. The plasma emitter is used to emit a plasma jet. The plasma emitter is connected to the plasma jet channel 12 of the powder feeding device. The plasma emitter can be a spray gun with plasma emission function. The working principle of the plasma emitter is to boost a low voltage to positive and negative high voltage through a boost circuit, and use the positive and negative high voltage to ionize air (mainly oxygen) to generate a large number of positive and negative ions. The number of negative ions is approximately 1.5 times the number of positive ions. The plasma emitter is prior art, and further details can be found in existing technology disclosures. This application does not impose any limitations. The gas source is a protective gas source, such as a nitrogen source or an argon source, and is connected to the protective gas channel 13. The powder storage tank can be used to store sealing powder and is connected to the powder channel 11.

[0056] Example 3

[0057] This application provides a method for sealing and modifying light metal workpieces, using the powder feeding device described in Example 1.

[0058] Please combine Figure 3 The sealing modification method in this application includes:

[0059] S1. The light metal workpiece to be sealed and modified is placed 50-70mm away from the powder feeding device on the side close to the scattering tube 20.

[0060] The light metal workpiece to be sealed and modified is located on one side of the scattering tube 20, which is conducive to the plasma jet carrying sealing powder ejected from the scattering tube 20 being sprayed onto the light metal workpiece to be sealed and modified.

[0061] S2. Sealing powder, plasma jet, and protective gas are introduced into the feeding pipe 10 through the powder channel 11, plasma jet channel 12, and protective gas channel 13, respectively. The plasma jet carrying the sealing powder and protective gas is sprayed from the feeding pipe 10 into the scattering pipe 20. At the same time, the fan blade 51 of the fan 50 rotates so that the plasma jet carrying the sealing powder and protective gas is scattered and sprayed from the powder passage of the fan blade 51 onto the surface of the light metal workpiece to be sealed and modified for sealing modification.

[0062] The rotation of the 5150 fan blades improves the uniformity of the sealing powder carried by the plasma jet, thereby improving the uniformity of the sealing powder reaching the surface of the light metal workpiece, ensuring that the pores of the light metal workpiece can be filled and improving its density.

[0063] In some embodiments, during the pore-sealing modification process, the relative motion speed between the light metal workpiece to be sealed and the powder feeding device is 20-200 m / min, and the voltage of the plasma jet is 500-700 V.

[0064] The voltage of the ejected plasma jet affects the temperature rise. The high-temperature plasma jet, ejected from the scattering tube 20, carries away heat and acts on the light metal workpiece to be sealed and modified. Heat is released onto the light metal workpiece, thus raising its temperature. Simultaneously, the plasma jet heats the sealing powder within the feeding tube 10, causing it to become liquid or semi-liquid. This liquid or semi-liquid sealing powder adheres to the surface of the high-temperature light metal workpiece, sealing the pores. The plasma jet voltage is controlled at 500-700V. Combined with the relative operating speed between the light metal workpiece and the powder feeding device, this ensures the sealing powder reaches a temperature of 350-450℃ upon reaching the workpiece. Excessive plasma jet voltage may pose safety hazards and cause excessive surface temperature and deformation of the workpiece; insufficient voltage may hinder the conversion of the sealing powder into a liquid or semi-liquid state, affecting the density of the modified light metal workpiece.

[0065] In some embodiments, the light metal workpiece to be sealed and modified is located below the powder feeding device, and the sealing and modification powder is sprayed from top to bottom, which can save energy; if the light metal workpiece to be sealed and modified is located on one side of the powder feeding device in the horizontal direction, the uniformity of the sprayed sealing and modification powder will be reduced to some extent under the action of gravity.

[0066] In some embodiments, after the sealing modification, the method further includes the following steps: reducing the voltage of the plasma jet at a rate of 40-60V / h while simultaneously stopping the introduction of sealing powder to cool the light metal workpiece. Reducing the voltage of the plasma jet lowers the temperature of the light metal workpiece, and the temperature of the sealing powder leaving the powder feeding device also gradually decreases. After adhering to the surface of the light metal workpiece, it gradually solidifies in the pores on the surface of the light metal workpiece, forming an adhesion layer with a thickness of 3-8mm between the light metal workpiece and the sprayed coating. In some embodiments, the voltage reduction rate of the plasma jet can be 45V / h, 50V / h, or 55V / h, etc.

[0067] The sealing modification method of this application will be further described below with reference to specific embodiments:

[0068] The light metal workpiece is an aluminum alloy workpiece. The aluminum alloy workpiece is placed 60mm below the powder feeding device, with the feeding pipe 10 of the powder feeding device on top and the scattering pipe 20 on the bottom. The powder feeding device moves at a horizontal speed of 110 m / min, while simultaneously feeding powder into the powder channel 11, feeding a plasma jet with a voltage of 600V into the plasma jet channel 12, and feeding argon into the protective gas channel 13. The plasma jet carries the sealing powder into the inner cavity of the feeding pipe 10. The sealing powder is heated and liquefied in the inner cavity, and dispersed and sprayed through the powder passage of the fan blade 51 of the scattering pipe 20 along with the plasma jet, and sprayed onto the aluminum alloy workpiece. As the powder feeding device moves from one end of the aluminum alloy workpiece to the other end, the spraying ends.

[0069] The sealing modification method provided by this invention has at least the following advantages:

[0070] 1. Compared with related technologies that use double-layer glow discharge plasma diffusion coating technology to seal the workpiece by repeated operation at high temperature, the powder feeding device of this invention only needs to spray once relative to the workpiece to complete the sealing and modification of the workpiece. Therefore, the workpiece has a short residence time at high temperature and is not easily deformed. Since there is no need for repeated spraying, there will be no overlapping areas or missing areas of spraying, which improves the uniformity of spraying.

[0071] 2. After the cooled sealing powder jet fills the gaps, it forms an adhesion layer between the surface of the light metal workpiece and the cold spray coating, which improves the bonding strength between the surface of the light metal workpiece and the cold spray coating.

[0072] It should be noted that the light metal workpiece to be sealed and modified can be first polished and then repeatedly cleaned in a cleaner to improve the cleanliness of the surface of the light metal workpiece, and then placed on the side of the powder feeding device near the scattering tube 20 for sealing and modification.

[0073] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0074] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A powder feeding device for spraying sealing powder onto light metal workpieces, characterized in that, include: The feeding tube has a feeding end and a discharging end arranged opposite to each other. The feeding end is provided with a powder channel, a plasma jet channel, and a protective gas channel, all of which are connected to the inner cavity of the feeding tube. The discharging end is provided with a fastening hole penetrating the side wall. A scattering tube is coaxially connected to the discharge end, and the scattering tube is rotatably connected to the discharge end; both the outer wall of the scattering tube and the inner wall of the discharge end are provided with mounting grooves, and the mounting groove of the discharge end is connected to the fastening hole. A connector connects the scattering tube and the feeding tube. Multiple connectors are provided and arranged radially around the axial direction of the scattering tube. Each connector includes a rotating ball and a fastener. The rotating ball is positioned between the discharge end and the mounting groove of the scattering tube. The radial dimension of the rotating ball is the same as the radial dimension of the mounting groove of the scattering tube. The fastener is located within a fastening hole and is hinged to the rotating ball. A fan, coaxially located inside the scattering tube, includes multiple fan blades that can rotate around the fan's axis. The multiple fan blades are distributed circumferentially along the scattering tube. Each fan blade is provided with multiple spaced-apart powder passage holes. The central axis of the powder passage hole is inclined towards the central axis of the feeding tube at one end near the feeding tube. The motor is located inside the scattering tube and is connected to the fan.

2. The powder feeding device according to claim 1, characterized in that, In each of the fan blades, the central axis of the powder passage is inclined toward the leading edge of the fan blade near the end of the feed tube.

3. The powder feeding device according to claim 2, characterized in that, The fan blade is curved, and the powder passage is perpendicular to the part of the fan blade where the powder passage is located.

4. The powder feeding device according to claim 1, characterized in that, The diameter of the powder passage hole decreases sequentially from the tip of the fan blade to the root.

5. The powder feeding device according to claim 1, characterized in that, In each of the fan blades, the density of the powder-passing holes decreases sequentially from the tip of the blade to the root.

6. The powder feeding device according to any one of claims 1-5, characterized in that, The gap between the tip of the fan blade and the inner wall of the scattering tube is 2mm to 4mm; the distance between the outermost powder passage of the fan and the inner wall of the scattering tube is 0.5mm to 1.5mm; the distance between the innermost powder passage of the fan and the central axis of the scattering tube is 5mm to 15mm. Along the direction from the feeding end to the discharging end, the radial dimension of the inner cavity of the feeding tube first decreases and then increases.

7. A method for sealing and modifying light metal workpieces, using the powder feeding device according to any one of claims 1-6, characterized in that, The sealing modification method includes: The light metal workpiece to be sealed and modified is placed 50-70mm away from the powder feeding device on the side closest to the scattering tube. Sealing powder, plasma jet, and protective gas are introduced into the feeding pipe through a powder channel, a plasma jet channel, and a protective gas channel, respectively. The plasma jet carrying the sealing powder and protective gas is sprayed from the feeding pipe into the scattering pipe. At the same time, the fan blades rotate so that the plasma jet carrying the sealing powder and protective gas is scattered and sprayed from the powder passage of the fan blades onto the surface of the light metal workpiece to be sealed and modified.

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