A powder feeding method for plasma spheroidized powder

Abstract

The present application belongs to the technical field of metal powder processing. The present application discloses a powder feeding method for plasma spheroidization powder, comprising the following steps: after the powder is fed into the powder feeding tube, the powder is transported along the powder feeding section of the powder feeding tube in a straight motion trajectory; then the powder enters the powder outlet section of the powder feeding tube, and during the powder transportation process in the powder outlet section, the inner wall cross-section of the powder outlet section is continuously reduced, so that the flow rate of the powder increases; after the powder is output from the outlet of the powder outlet section, the powder forms a convergence, and the cross-sectional area of ​​the airflow formed by the powder increases, but the cross-sectional area of ​​the airflow formed by the powder is smaller than the plasma area; during the movement of the powder feeding tube, the powder is cooled by the water cooling mechanism. The present application solves the problem in the prior art that it is difficult to ensure that all the powder to be processed can be accurately fed into the center area of ​​the plasma when the straight tube powder feeding device is conveying powder.

Description

Technical Field

[0001] The present application belongs to the technical field of metal powder processing, and specifically relates to a powder feeding method for plasma spheroidization powder. Background Art

[0002] Spherical powders have shown extensive application potential in many high-tech fields due to their excellent fluidity, extremely low stress state and outstanding bulk density. These characteristics make spherical powders an indispensable component of additive manufacturing, precision integrated circuit manufacturing, efficient thermal management materials and new energy technologies. In particular, spherical powders prepared by advanced plasma spheroidization methods combine the advantages of uniform powder dispersion, high purity and near-perfect sphericity, further consolidating their leading position in the field of spherical powder preparation.

[0003] In terms of the core plasma generators of powder spheroidization technology, there are currently three main types: radio frequency plasma generators, microwave plasma generators, and direct current plasma generators. Although radio frequency and microwave plasma generators are technically capable of providing a high-quality plasma environment, their high equipment costs and relatively low output limit their application in large-scale production. In contrast, direct current plasma generators have become an ideal choice for large-scale production of spherical powders due to their low cost, high efficiency, and wide applicability.

[0004] The plasma excited by the DC plasma generator has high energy concentration and density, and also has a significant temperature gradient, which provides ideal conditions for the rapid spheroidization of powders. Specifically, irregularly shaped powder particles will experience rapid heating until melting when passing through the plasma area, and then rapidly cool and solidify under the action of the extremely high temperature gradient, and finally transform into spherical powders with smooth surface and regular shape.

[0005] However, in actual operation, DC plasma generation devices also face a series of challenges. In particular, although the temperature in the center of the plasma is extremely high, this high-temperature area is relatively narrow, which makes the effective handling of powder complicated. When the traditional straight-tube powder feeding device is conveying powder, the powder area will gradually expand after leaving the device, making it difficult to ensure that all powder to be processed can be accurately delivered to the center of the plasma. In order to deal with this problem, although it can be solved by reducing the size of the powder feeding device and reducing the amount of powder fed, this will undoubtedly sacrifice production efficiency. In addition, the high temperature gradient in the plasma area and the resulting large rigidity make it impossible for some powders to actually enter the plasma area even if they seem to be close to the plasma area due to insufficient energy, but instead they are carried away by the turbulence of the plasma. These problems not only seriously weaken the spheroidization effect of the plasma, but also greatly limit the potential of DC plasma technology in increasing the yield of spherical powders. Summary of the invention

[0006] The embodiment of the present application provides a powder feeding method for plasma spheroidization powder, which solves the problem in the prior art that it is difficult to ensure that all powder to be processed can be accurately fed into the center area of ​​the plasma when conveying powder using a straight tube type powder feeding device.

[0007] In order to achieve the above object, an embodiment of the present invention provides a powder feeding method for plasma spheroidization powder, comprising the following steps:

[0008] After the powder is fed into the powder feeding pipe, the powder is transported along the powder feeding section of the powder feeding pipe in a linear motion trajectory;

[0009] Then the powder enters the powder outlet section of the powder delivery pipe. During the powder delivery process, the inner wall section of the powder outlet section is continuously reduced, so that the flow rate of the powder increases.

[0010] After the powder is discharged from the outlet of the powder discharge section, the powder forms a convergence flow, and the cross-sectional area of ​​the airflow formed by the powder becomes larger, but the cross-sectional area of ​​the airflow formed by the powder is smaller than that of the plasma region;

[0011] The powder is cooled by a water cooling mechanism during the movement of the powder feeding tube.

[0012] In one possible implementation, a plurality of spiral air guide grooves are evenly distributed around the inner wall of the powder outlet section, and the outer layer of the powder airflow rotates under the action of the air guide grooves, so that after the powder is output from the outlet of the powder outlet section, the cross-sectional area of ​​the airflow formed by the powder is reduced.

[0013] In one possible implementation, during the powder conveying process in the powder discharge section, the inner wall cross-section of the powder discharge section continuously decreases, the flow rate of the powder increases, and after the powder moves 1 / 2 to 3 / 4 of the length of the powder discharge section in the powder discharge section, the powder rotates under the action of the air guide groove.

[0014] In a possible implementation, the flow rate of the powder airflow is adjusted by adjusting the angle between the inner wall of the powder outlet section and the axis of the powder outlet section, thereby changing the converging effect of the powder.

[0015] In a possible implementation, the rotational force and axial force of the powder are adjusted by adjusting the rotation angle of the gas guide groove so that all the powder gas flow enters the plasma region.

[0016] In a possible implementation, the rotation angle of the air guide groove is 7°, and the angle between the inner wall of the powder outlet section and the axis of the powder outlet section is 15°.

[0017] In one possible implementation, cooling water of a set pressure is injected into the inner water-cooling chamber of the cylindrical structure. The cooling water is injected along the tangent direction of the inner water-cooling chamber, so that the cooling water forms a turbulent flow state until it moves to the intersection of the outer water-cooling chamber and the inner water-cooling chamber. During this process, the cooling water cools the powder delivery pipe.

[0018] In a possible implementation, the outer water-cooling chamber is a cylindrical structure, and the outer water-cooling chamber is mounted on the inner water-cooling chamber. The cooling water enters the outer water-cooling chamber from the intersection of the outer water-cooling chamber and the inner water-cooling chamber until the cooling water is discharged from the outlet at the end of the outer water-cooling chamber. In this process, the cooling water cools the cooling water in the inner water-cooling chamber.

[0019] In a possible implementation, when the end cover of the water cooling mechanism is installed, the conical docking ring on the end cover rotates and moves laterally into the conical docking groove on the end face of the powder delivery pipe, forming a conical sealing surface between the docking groove and the docking ring.

[0020] In a possible implementation, the water-cooled outer sealing ring between the docking groove and the docking ring side wall and the groove bottom sealing ring of the docking groove can realize a double sealing structure, thereby reducing the probability of water leakage from the water-cooling cavity through the sealing surface between the end cover and the powder delivery pipe.

[0021] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0022] The embodiment of the present invention provides a powder feeding method for plasma spheroidization powder. During the powder conveying process in the powder discharge section, the cross section of the powder discharge section is continuously reduced. According to the Bernoulli principle, the flow rate of the powder increases, and the powder forms a convergence. Therefore, the airflow of the powder after being output from the outlet of the powder discharge section has the characteristics of high energy and fast flow rate, so that the cross-sectional area of ​​the powder airflow after being output from the outlet of the powder discharge section is not easy to increase relative to the existing powder airflow, that is, after the powder is output from the outlet of the powder discharge section, the cross-sectional area of ​​the airflow formed by the powder will increase, but it is much smaller than the cross-sectional area in the prior art, so it can fully meet the receiving range of the plasma area. The powder airflow output from the outlet of the powder discharge section has the characteristics of high energy and fast flow rate. Therefore, the outlet of the powder discharge section is more prone to ablation than the prior art. The present invention cools the powder delivery pipe through a water cooling mechanism, which can solve this problem well, thereby improving the service life of the device. The present invention can ensure that all powders enter the plasma area and prevent them from being carried away by the turbulent flow of the plasma, thereby ensuring the spheroidization effect of the plasma, thereby greatly improving the yield of spherical powder produced by DC plasma. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 This is a schematic structural diagram of a powder feeding device for plasma spheroidization powder provided in Example 1 of the present invention.

[0025] Figure 2 A schematic diagram of the structure of the powder discharge section provided in an embodiment of the present invention Figure 1 .

[0026] Figure 3 A schematic diagram of the structure of the powder discharge section provided in an embodiment of the present invention Figure 2 .

[0027] Figure 4 This is a schematic diagram of the structure of a powder feeding device for plasma spheroidization powder provided in the second embodiment of the present invention.

[0028] Figure 5 This is a schematic diagram of the separation state of the end cover of the powder feeding device for plasma spheroidization powder provided in the second embodiment of the present invention.

[0029] Figure markings: 1-powder delivery pipe; 2-powder delivery section; 3-powder outlet section; 4-air guide groove; 5-water inlet pipe; 6-water return pipe; 7-end cover; 8-first blocking ring; 9-cooling water inlet joint; 10-second blocking ring; 11-cooling water outlet joint; 12-powder delivery sealing ring; 13-annular body; 14-annular surface; 15-water-cooled outer sealing ring; 16-water-cooled inner sealing ring; 17-connecting seat; 18-docking groove; 19-groove bottom sealing ring; 20-docking ring; 21-inner water-cooling cavity; 22-outer water-cooling cavity. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] In the description of the embodiments of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limitations on the present invention. The terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. In addition, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present invention can be understood according to the specific circumstances.

[0032] like Figures 1 to 5 As shown, the powder feeding method for plasma spheroidization powder provided in the embodiment of the present invention adopts a powder feeding device for plasma spheroidization powder, including a powder feeding pipe 1 and a water cooling mechanism.

[0033] The powder delivery pipe 1 includes a powder delivery section 2 and a powder outlet section 3. The inner wall of the powder outlet section 3 is a conical structure. The large end of the powder outlet section 3 is connected to the outlet of the powder delivery section 2. The inner wall of the powder outlet section 3 is evenly distributed with multiple air guide grooves 4 in the circumferential direction. The air guide grooves 4 are spirally arranged along the axis of the powder outlet section 3.

[0034] The powder delivery pipe 1 is provided with a water cooling mechanism.

[0035] In this embodiment, the cone half angle of the inner wall of the powder outlet section 3 is 5° to 60°.

[0036] In this embodiment, the rotation angle of the air guide groove 4 is 3° to 15°.

[0037] In this embodiment, the water cooling mechanism includes a water inlet pipe 5 , a water return pipe 6 and an end cover 7 .

[0038] The water inlet pipe 5 is coaxially sleeved on the powder delivery pipe 1, and the rear end of the water inlet pipe 5 is sealed and connected to the outer wall of the powder delivery pipe 1 through a first blocking ring 8. A cooling water inlet joint 9 is arranged at the rear of the water inlet pipe 5.

[0039] The return water pipe 6 is coaxially sleeved on the water inlet pipe 5, the rear end of the return water pipe 6 is sealedly connected to the outer wall of the water inlet pipe 5 through a second blocking ring 10, a cooling water outlet joint 11 is provided at the rear of the return water pipe 6, the front end of the return water pipe 6 is sealedly connected to the outlet end of the powder delivery pipe 1 through an end cover 7, and the front end of the water inlet pipe 5 and the end cover 7 are spaced apart.

[0040] It should be noted that the water cooling mechanism forms a Figure 1 The outer water cooling chamber 22 and the inner water cooling chamber 21 are shown. The first blocking ring 8 and the second blocking ring 10 are connected by welding. The temperature at the end cover 7 is high, so it is easy to be damaged. The independent design can not only reduce the processing cost, but also facilitate replacement. The water cooling mechanism forms the heat exchange space shown in the figure, and the cross-section of one side of the heat exchange space is n-shaped. The cooling water inlet joint 9 is tangent to the inner wall of the water inlet pipe 5, thereby improving the heat exchange efficiency.

[0041] In the first embodiment, the powder delivery section 2 and the powder outlet section 3 are connected by threads, and a powder delivery sealing ring 12 is provided between the butt surfaces of the powder delivery section 2 and the powder outlet section 3 .

[0042] It should be noted that the powder feeding seal ring 12 is used to ensure the sealing between the powder feeding section 2 and the powder outlet section 3. The independent design of the powder feeding section 2 can not only reduce the processing cost, but also be easy to replace.

[0043] In the first embodiment, the end cover 7 includes a connected annular body 13 and an annular surface 14, the annular body 13 is a cylindrical structure, and the cross-section of the annular body 13 and the annular surface 14 is an L-shaped structure. The end of the annular body 13 is threadedly connected to the front end of the return pipe 6, and a water-cooled outer sealing ring 15 is provided between the butt surface of the annular body 13 and the return pipe 6.

[0044] A water-cooled inner sealing ring 16 is provided between the annular surface 14 and the butt joint surface of the powder feeding section 2 .

[0045] It should be noted that the joints between the annular surface 14 and the powder delivery section 2, the joints between the powder delivery section 2 and the powder outlet section 3, and the joints between the annular body 13 and the water return pipe 6 are all provided with steps, which can improve the sealing effect and also make the joints transition smoothly. The annular surface 14 and the powder delivery section 2 are connected in an abutting manner by the threaded connection between the annular body 13 and the water return pipe 6, and the water-cooled inner sealing ring 16 is compressed to achieve a sealing effect.

[0046] The powder delivery section 2 can be made of stainless steel, aluminum alloy, copper alloy or titanium alloy, and stainless steel is preferred in this embodiment. The powder outlet section 3 can be made of stainless steel, aluminum alloy, copper alloy, tungsten alloy or titanium alloy, and copper alloy is preferred in this embodiment. Copper alloy has high thermal conductivity and good heat transfer effect, so the powder delivery pipe 1 can be easily cooled by a water cooling mechanism.

[0047] In this embodiment, a connecting seat 17 is installed on the water return pipe 6, and a mounting hole is provided on the connecting seat 17.

[0048] It should be noted that the device is installed on the plasma spheroidization equipment or the plasma spheroidization chamber via the connection seat 17 .

[0049] In the second embodiment, an annular docking groove 18 is provided in the circumferential direction of the end surface of the powder feeding section 2 . The cross section of the docking groove 18 is a conical structure. A groove bottom sealing ring 19 is provided at the bottom of the docking groove 18 .

[0050] The end cover 7 includes a circular body 13, a circular surface 14 and a docking ring 20. The circular body 13 is a cylindrical structure. The rear end of the circular body 13 is threadedly connected to the front end of the return pipe 6. A water-cooled outer sealing ring 15 is provided between the docking surfaces of the circular body 13 and the return pipe 6.

[0051] The outer ring of the annular surface 14 is connected to the front end of the annular body 13, and the inner ring of the annular surface 14 is provided with a docking ring 20. The cross-section of the side wall of the docking ring 20 is a conical structure. The docking ring 20 is inserted into the docking groove 18, and the end of the docking ring 20 abuts against the groove bottom sealing ring 19.

[0052] In the second embodiment, a water-cooled inner sealing ring 16 is provided on the outer wall of the docking ring 20 , and the inner wall of the docking groove 18 abuts against the water-cooled inner sealing ring 16 .

[0053] It should be noted that, in this embodiment, the powder feeding section 2 and the powder discharging section 3 are an integrated structure, so there is no need to worry about the sealing problem between the powder feeding section 2 and the powder discharging section 3.

[0054] The various sealing rings of this embodiment can be made of fluororubber or silicone rubber.

[0055] like Figures 1 to 5 As shown, the powder feeding method for plasma spheroidization powder provided in an embodiment of the present invention comprises the following steps:

[0056] After the powder is fed into the powder feeding pipe 1 , the powder is transported along the powder feeding section 2 of the powder feeding pipe 1 in a linear motion trajectory.

[0057] Then the powder enters the powder outlet section 3 of the powder feeding pipe 1. During the powder conveying process in the powder outlet section 3, the inner wall cross-section of the powder outlet section 3 is continuously reduced, so that the flow rate of the powder increases.

[0058] After the powder is discharged from the outlet of the powder discharge section 3, the powder forms a convergence flow, and the cross-sectional area of ​​the airflow formed by the powder becomes larger, but the cross-sectional area of ​​the airflow formed by the powder is smaller than the plasma area.

[0059] When the powder is moving in the powder delivery tube 1 , the powder delivery tube 1 is cooled by a water cooling mechanism.

[0060] It should be noted that, during the powder delivery process of the powder delivery section 3, the cross-section of the powder delivery section 3 is continuously reduced. According to the Bernoulli principle, the flow rate of the powder increases, and the powder forms a confluence. Therefore, the airflow of the powder after being output from the outlet of the powder delivery section 3 has the characteristics of high energy and fast flow rate, so that the cross-sectional area of ​​the powder airflow after being output from the outlet of the powder delivery section 3 is not easy to increase relative to the existing powder airflow, that is, after the powder is output from the outlet of the powder delivery section 3, the cross-sectional area of ​​the airflow formed by the powder will increase, but it is much smaller than the cross-sectional area in the prior art, so it can fully meet the receiving range of the plasma area. The powder airflow output from the outlet of the powder delivery section 3 has the characteristics of high energy and fast flow rate. Therefore, the outlet of the powder delivery section 3 is more prone to ablation than the prior art. The present invention cools the powder delivery pipe 1 through a water cooling mechanism, which can solve this problem well, thereby improving the service life of the device. The present invention can ensure that all powders enter the plasma area, prevent being carried away by the turbulent flow of the plasma, and then ensure the spheroidization effect of the plasma, thereby greatly improving the yield of spherical powder produced by DC plasma.

[0061] The device is tested for sealing before use. First, the water source is connected through the cooling water inlet joint 9 and the cooling water outlet joint 11, and then 0.4MPa to 0.6MPa of cooling water is introduced for 30 minutes. If there is no cooling water leakage, the cooling water is disconnected and the cooling water in the pipeline is discharged. Finally, the device is installed on the equipment through the connecting seat 17. If cooling water leakage occurs due to ablation during pressure or use, the device is first removed from the equipment through the connecting seat 17, and then the various sealing rings are checked for failure. If they fail, the sealing rings are replaced, and the powder delivery pipe 1 and the end cover 7 are checked for serious ablation. If normal use is affected, they are replaced.

[0062] In this embodiment, a plurality of spiral air guide grooves 4 are evenly distributed around the inner wall of the powder outlet section 3. The outer layer of the powder airflow rotates under the action of the air guide grooves 4, so that after the powder is output from the outlet of the powder outlet section 3, the cross-sectional area of ​​the airflow formed by the powder is reduced.

[0063] It should be noted that the outer layer of the powder airflow rotates under the action of the air guide groove 4. By rotating the outer layer of the powder airflow, the cross-sectional area of ​​the powder airflow after being output from the outlet of the powder outlet section 3 can be less likely to increase relative to the existing powder airflow. Such a powder airflow can break through the rigidity of the plasma area and smoothly reach the plasma area.

[0064] In this embodiment, during the transportation of the powder in the powder outlet section 3, the inner wall cross-section of the powder outlet section 3 is continuously reduced, and the flow rate of the powder increases. After the powder moves 1 / 2 to 3 / 4 of the length of the powder outlet section 3 in the powder outlet section 3, the powder rotates under the action of the air guide groove 4.

[0065] In this embodiment, the projected length of the air guide groove 4 on the axis of the powder outlet section 3 is 1 / 4 to 1 / 2 of the length of the powder outlet section 3 .

[0066] It should be noted that the air guide groove 4 will reduce the energy of the powder airflow, that is, the speed of the powder airflow will be reduced, so the length setting of the air guide groove 4 can also reduce the loss of the speed of the powder airflow. If the air guide groove 4 is set at the inlet of the powder outlet section 3, the axial force of the airflow will be converted into a rotational force in advance, and the converging effect produced by the inner wall of the powder outlet section 3 of the conical structure will be superimposed. The airflow may not reach the outlet of the powder outlet section 3, that is, the powder airflow will gather at a certain position in the middle of the powder outlet section 3, so that the speed loss is greater, and it may even be blocked in the powder outlet section 3. The length setting of the air guide groove 4 can also reduce the difficulty of processing.

[0067] In this embodiment, the flow rate of the powder airflow is adjusted by adjusting the angle between the inner wall of the powder outlet section 3 and the axis of the powder outlet section 3, and the converging effect of the powder is changed.

[0068] In this embodiment, the rotational force and axial force of the powder are adjusted by adjusting the rotation angle of the gas guide groove 4, so that all the powder airflow enters the plasma region.

[0069] In this embodiment, the rotation angle of the air guide groove 4 is 7°, and the angle between the inner wall of the powder outlet section 3 and the axis of the powder outlet section 3 is 15°.

[0070] It should be noted that the cone half angle of the inner wall of the powder outlet section 3 is preferably 15°. This size can make the powder airflow transition smoother. If the cone half angle of the inner wall of the powder outlet section 3 is too large, the powder airflow velocity will increase, causing the powder to accumulate at the powder outlet, thereby blocking the powder feeding pipe 1. If the cone half angle of the inner wall of the powder outlet section 3 is too small, the confluence effect will also be limited.

[0071] The rotation angle of the air guide groove 4 refers to the angle between the line connecting the two ends of the air guide groove 4 and the axis of the powder outlet section 3. The rotation angle of the air guide groove 4 is preferably 7°. The air guide groove 4 can convert the axial force of the powder airflow into a circumferential rotational force. This size is obtained by comprehensive analysis based on the cone half angle and the force required for the powder airflow to rotate. If the rotation angle of the air guide groove 4 is too large, the processing itself will be difficult, and if the rotational force of the powder airflow is too large, the axial force will be reduced, making it difficult to reach the plasma area. If the rotational force of the powder airflow is too small, no effect will be achieved.

[0072] In this embodiment, cooling water of a set pressure is injected into the inner water-cooling chamber 21 of the cylindrical structure. The cooling water is injected along the tangential direction of the inner water-cooling chamber 21, so that the cooling water is converted into a turbulent flow state until it moves to the intersection of the outer water-cooling chamber 22 and the inner water-cooling chamber 21. During this process, the cooling water cools the powder delivery pipe 1.

[0073] In this embodiment, the outer water cooling chamber 22 is a cylindrical structure, and the outer water cooling chamber 22 is mounted on the inner water cooling chamber 21. The cooling water enters the outer water cooling chamber 22 from the intersection of the outer water cooling chamber 22 and the inner water cooling chamber 21 until the cooling water is discharged from the outlet at the end of the outer water cooling chamber 22. In this process, the cooling water cools the cooling water in the inner water cooling chamber 21.

[0074] It should be noted that the cooling water is injected along the tangent direction of the inner water cooling chamber 21, so that the cooling water forms a turbulent flow state, and the water in the outer water cooling chamber 22 is also in a turbulent flow state. Compared with the prior art in which the cooling water is directly injected to form a laminar flow state, the convective heat transfer coefficient of the turbulent flow is higher than that of the laminar flow, thereby improving the heat exchange efficiency.

[0075] In this embodiment, when the end cover 7 of the water cooling mechanism is installed, the conical docking ring 20 on the end cover 7 enters the conical docking groove 18 on the end face of the powder feeding pipe 1 in a rotating and transverse manner, and a conical sealing surface is formed between the docking groove 18 and the docking ring 20.

[0076] In this embodiment, the water-cooled outer sealing ring 15 between the docking groove 18 and the side wall of the docking ring 20 and the groove bottom sealing ring 19 of the docking groove 18 can realize a double sealing structure, thereby reducing the probability of water leakage from the water-cooling cavity through the sealing surface between the end cover 7 and the powder feeding pipe 1.

[0077] It should be noted that the gas outlet of the powder outlet section 3 and the end cover 7 are sealed with a conical structure docking ring 20. The sealing surface of the conical structure can form a closer contact surface in the process of the docking ring 20 gradually moving into the docking groove 18. At the same time, under the action of the groove bottom sealing ring 19 and the water-cooled outer sealing ring 15, the sealing effect can be greatly improved, thereby avoiding the problem of cooling water leakage and contaminating the powder. When in use, the groove bottom sealing ring 19 and the water-cooled outer sealing ring 15 fail due to ablation, and the sealing structure of this embodiment will not have the problem of large-scale leakage of cooling water.

[0078] In this embodiment, it is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the above description, and therefore it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention.

Claims

1. A powder feeding method for plasma spheroidization powder, characterized in that: The following steps are involved: After the powder is fed into the powder feeding pipe (1), the powder is transported along the powder feeding section (2) of the powder feeding pipe (1) in a linear motion trajectory; The powder then enters the powder outlet section (3) of the powder delivery pipe (1). During the powder delivery process in the powder outlet section (3), the inner wall cross-section of the powder outlet section (3) is continuously reduced, thereby increasing the flow rate of the powder. The inner wall of the powder outlet section (3) is evenly distributed with a plurality of spiral air guide grooves (4) in the circumferential direction, and after the powder moves 1 / 2 to 3 / 4 of the length of the powder outlet section (3) in the powder outlet section (3), the outer layer of the powder airflow rotates under the action of the air guide grooves (4); After the powder is discharged from the outlet of the powder discharge section (3), the powder forms a convergence flow, and the cross-sectional area of ​​the airflow formed by the powder becomes larger. The air guide groove (4) reduces the increase in the cross-sectional area of ​​the airflow formed by the powder; however, the cross-sectional area of ​​the airflow formed by the powder is smaller than the plasma area; and the powder is cooled by the water cooling mechanism while the powder delivery tube (1) is moving.

2. The powder feeding method for plasma spheroidization powder according to claim 1, characterized in that: By adjusting the angle between the inner wall of the powder outlet section (3) and the axis of the powder outlet section (3), the flow rate of the powder airflow is adjusted, and the converging effect of the powder is changed.

3. The powder feeding method for plasma spheroidization powder according to claim 1, characterized in that: The rotational force and axial force of the powder are adjusted by adjusting the rotation angle of the air guide groove (4), so that the powder airflow can all enter the plasma area.

4. The powder feeding method for plasma spheroidization powder according to claim 3, characterized in that: The rotation angle of the air guide groove (4) is 7°, and the angle between the inner wall of the powder outlet section (3) and the axis of the powder outlet section (3) is 15°.

5. The powder feeding method for plasma spheroidization powder according to claim 2, characterized in that: Cooling water of a set pressure is injected into the inner water cooling chamber (21) of the cylindrical structure. The cooling water is injected along the tangent direction of the inner water cooling chamber (21) so that the cooling water forms a turbulent flow state until it moves to the intersection of the outer water cooling chamber (22) and the inner water cooling chamber (21). During this process, the cooling water cools the powder delivery pipe (1).

6. The powder feeding method for plasma spheroidization powder according to claim 5, characterized in that: The outer water cooling chamber (22) is a cylindrical structure. The outer water cooling chamber (22) is sleeved on the inner water cooling chamber (21). Cooling water enters the outer water cooling chamber (22) from the intersection of the outer water cooling chamber (22) and the inner water cooling chamber (21) until the cooling water is discharged from the outlet at the end of the outer water cooling chamber (22). During this process, the cooling water cools the cooling water in the inner water cooling chamber (21).

7. The powder feeding method for plasma spheroidization powder according to claim 6, characterized in that: When the end cover (7) of the water cooling mechanism is installed, the conical docking ring (20) on the end cover (7) enters the conical docking groove (18) on the end face of the powder delivery pipe (1) in a rotating and transverse manner, and a conical sealing surface is formed between the docking groove (18) and the docking ring (20).

8. The powder feeding method for plasma spheroidization powder according to claim 7, characterized in that: The water-cooled outer sealing ring (15) between the side wall of the docking groove (18) and the docking ring (20) and the groove bottom sealing ring (19) of the docking groove (18) can realize a double sealing structure, thereby reducing the probability of water leaking from the water-cooling cavity through the sealing surface between the end cover (7) and the powder delivery pipe (1).

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