Electrode induction and plasma combined metal powder production apparatus and method

Abstract

This invention relates to a metal powder manufacturing apparatus and method combining electrode induction and plasma, comprising a metal rod, an induction coil, an atomization chamber, and a gas flow nozzle, and further comprising a driving device, a plasma device, and a heating chamber. A connecting channel is provided between the heating chamber and the atomization chamber. The induction coil is disposed in the heating chamber, and the metal rod extends into the induction coil. The driving device is connected to the metal rod and can drive the metal rod to rotate around its own central axis, and simultaneously drive the metal rod to move axially and extend into the atomization chamber through the connecting channel. The inner end of the metal rod extending into the atomization chamber is the melting working end. The plasma device includes several plasma spray guns, which can spray plasma jets onto the melting working end of the metal rod located in the atomization chamber. The gas flow nozzle can blow airflow below the melting working end of the metal rod located in the atomization chamber.

Description

Technical Field

[0001] This invention relates to the field of metal powder manufacturing technology, and specifically to a metal powder manufacturing apparatus and method that combines electrode induction and plasma. Background Technology

[0002] Additive manufacturing, also known as 3D printing, is an emerging technology that uses layer-by-layer material deposition to create three-dimensional components. Compared to traditional technologies, additive manufacturing simplifies manufacturing processes, shortens manufacturing cycles, and allows for the flexible customization of complex structural parts to meet specific needs. Currently, additive manufacturing is widely used in aerospace, automotive, medical, education, architecture, and art, among other fields. To meet the process requirements of additive manufacturing, metal powders must possess characteristics such as good sphericity, low surface roughness, a narrow particle size distribution range, low nitrogen and oxygen content, and high purity.

[0003] Currently, most metal powders used in additive manufacturing are prepared through gas atomization. In Electrode Induction Gas Atomization (EIGA), a metal rod is heated by high-frequency alternating current from an induction coil, and the molten metal is atomized into powder under the action of high-pressure inert gas. EIGA eliminates the need for crucibles and flow guides during the melting process, effectively preventing contamination of the molten metal. However, the EIGA method suffers from a small, unstable flow of molten metal, resulting in low production efficiency. This is particularly true for metals with high conductivity, where their low resistivity and low eddy current losses lead to slow heating, requiring higher power and longer melting times, and sometimes even preventing complete melting. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the technical problem to be solved by the present invention is to provide a metal powder preparation device and method that combines electrode induction and plasma, which can effectively improve the powder atomization effect of metal powder, especially highly conductive metal.

[0005] To achieve the above objectives, the present invention provides a metal powder manufacturing apparatus combining electrode induction and plasma, comprising a metal rod, an induction coil, an atomization chamber, and an airflow nozzle, and further comprising a driving device, a plasma device, and a heating chamber. A connecting channel is provided between the heating chamber and the atomization chamber. The induction coil is disposed in the heating chamber, and the metal rod extends into the induction coil. The driving device is connected to the metal rod and can drive the metal rod to rotate around its own central axis, and simultaneously drive the metal rod to move axially and extend into the atomization chamber through the connecting channel. The inner end of the metal rod extending into the atomization chamber is the melting working end. The plasma device includes several plasma spray guns, which can spray plasma jets onto the melting working end of the metal rod located in the atomization chamber. The airflow nozzle can blow airflow below the melting working end of the metal rod located in the atomization chamber.

[0006] Furthermore, the angle between the central axis of the metal rod and the vertical direction is 0° to 30°.

[0007] Furthermore, the melting working end of the metal rod has a pointed tip that gradually decreases in size from top to bottom.

[0008] Furthermore, the plasma gun is tilted, and the ejected plasma jet is tilted downwards.

[0009] Furthermore, there are multiple plasma spray guns, which are spaced apart circumferentially along the metal rod.

[0010] Furthermore, there are multiple airflow nozzles, which are spaced apart along the circumference of the metal rod and are staggered from the plasma spray gun.

[0011] Furthermore, the induction coil is a conical coil, and it gradually decreases in size along the direction from the outer end to the inner end of the metal rod.

[0012] This invention also provides a method for preparing metal powder using a combination of electrode induction and plasma, employing the aforementioned metal powder preparation equipment, and comprising the following steps:

[0013] S1. Preheating: The induction coil operates in the heating chamber to preheat the metal rod to a specified temperature, which is lower than the melting point temperature Tm of the metal rod.

[0014] S2, Atomization: The melting working end of the metal rod is in the atomization working position in the atomization chamber. The driving device drives the metal rod to rotate, the induction coil maintains the heating working state, the plasma spray gun sprays plasma jets onto the melting working end of the metal rod, further heating the melting working end to the melting temperature, and the airflow nozzle blows airflow below the melting working end.

[0015] Furthermore, in step S1, the induction coil heats the metal rod to 0.6Tm to 0.9Tm.

[0016] Furthermore, in step S2, the metal rod rotates at a speed of 5000 to 10000 revolutions per minute.

[0017] As described above, the metal powder production equipment and method of the present invention have the following advantages;

[0018] The metal rod is preheated to a specified temperature before entering the atomization chamber using a heating chamber and induction coil. Then, a plasma jet is used as an additional heat source to rapidly and stably heat the metal rod to its melting temperature within the atomization chamber. This method is particularly effective for heating highly conductive, high-melting-point metal rods. The plasma jet atomizes the molten metal while heating, and together with the high-pressure airflow from the airflow nozzle, the molten metal is atomized. The medium-speed rotation of the metal rod improves the stability of atomization and the fine powder yield. Compared with traditional EIGA, this method effectively improves the efficiency of powder production and the yield of metal powder. The resulting powder has advantages such as being pollution-free, highly pure, having good sphericity, a high fine powder yield, and fewer satellite powders and hollow powders. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the metal powder production equipment of the present invention.

[0020] Explanation of icon numbers

[0021] 1. Metal rod

[0022] 2. Induction coil

[0023] 3. Atomization Chamber

[0024] 4 partitions

[0025] 41 Connecting Channels

[0026] 5 Heating Chamber

[0027] 6. Plasma spray gun

[0028] 7. Spray gun connection mechanism

[0029] 8. Airflow nozzles

[0030] 9. Powder Collection Chamber Detailed Implementation

[0031] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0032] It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings of this specification are merely for illustrative purposes to aid those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms such as "upper," "lower," "left," "right," and "middle" used in this specification are merely for clarity and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0033] See Figure 1 This invention provides a metal powder manufacturing device combining electrode induction and plasma, including a metal rod 1, an induction coil 2, an atomization chamber 3, and an airflow nozzle 8. It also includes a driving device (not shown in the drawings), a plasma device, and a heating chamber 5. A connecting channel 41 is provided between the heating chamber 5 and the atomization chamber 3. The induction coil 2 is disposed in the heating chamber 5, and the metal rod 1 extends into the induction coil 2. The driving device is connected to the metal rod 1 and can drive the metal rod 1 to rotate around its own central axis. Simultaneously, it can drive the metal rod 1 to move along its axial direction and extend into the atomization chamber 3 via the connecting channel 41. The inner end of the metal rod 1 extending into the atomization chamber 3 is the melting working end. The plasma device includes several plasma spray guns 6, which can spray plasma jets onto the melting working end of the metal rod 1 located in the atomization chamber 3. The area sprayed with the plasma jet may also include a certain area below the melting working end. The airflow nozzle 8 can blow airflow below the melting working end of the metal rod 1 located in the atomization chamber 3.

[0034] The main working principle of the metal powder manufacturing equipment involved in this invention is as follows: Before entering the atomization chamber 3, the metal rod 1 is preheated to a specified temperature in the heating chamber 5 by induction coil 2. This temperature is not higher than the melting temperature of the metal rod 1, and can be determined according to actual needs. During the heating process of induction coil 2, the metal rod 1 preferably rotates around its own central axis to improve the heating effect. When the metal rod 1 reaches the specified temperature and the melting working end is in a specified position in the atomization chamber 3 (denoted as the atomization working position), the atomization work is ready to begin. Preferably, the metal rod 1 is moved to the atomization working position after the induction coil 2 has heated the metal rod 1 to the specified temperature. Of course, it is also possible to move the metal rod 1 to the atomization working position while heating it. During atomization, the drive unit rotates the metal rod 1, while the induction coil 2 remains heated. The plasma nozzle 6 of the plasma device sprays a plasma jet onto the melting end of the metal rod 1, further heating it to the melting point temperature Tm. The airflow nozzle 8 blows airflow below the melting end, and the plasma jet further heats the preheated melting end of the metal rod 1. The surface of the melting end melts rapidly. A portion of the molten metal on the surface of the melting end is affected by the centrifugal force generated by the rotation of the metal rod 1 and the plasma. Under the combined action of the jet impact force, the molten metal leaving the surface is atomized. Another portion of the molten metal that does not leave the surface of the metal rod 1 in time due to centrifugal force and the impact force of the plasma jet will collect under gravity and form a free-falling molten metal stream. Below the melting working end, the molten metal stream is dispersed by the high-speed airflow from the airflow nozzle 8, forming fine metal droplets. Furthermore, when the plasma jet area also includes a certain area below the melting working end, the falling molten metal stream is also simultaneously affected by the blowing action of the plasma jet. The airflow blown by the airflow nozzle 8 is preferably an inert gas such as argon. In the atomization chamber 3, the metal droplets are heated by the plasma jet, increasing the atomization temperature and preventing premature solidification, thus improving sphericity and increasing the kinetic energy of the atomizing gas, thereby improving the yield of fine powder. A powder collection chamber 9 is generally provided below the atomization chamber 3 to collect the atomized and solidified metal particles. Throughout the heating and atomization process, the heating chamber 5 and the atomization chamber 3 are filled with inert gas to protect the metal from oxidation.

[0035] In this invention, the metal rod 1 is first preheated by the induction coil 2, and then rapidly heated and blown by the plasma jet, which can efficiently melt the metal rod 1, especially the metal rod 1 with high conductivity and high melting point. During the process of metal melting and liquid dripping, it does not come into contact with any medium. The plasma jet has the functions of heating and atomizing metal droplets together with the airflow. Furthermore, the rotation of the metal rod 1 improves the stability of atomization and the fine powder rate.

[0036] See Figure 1The present invention will be further described below with reference to a specific embodiment:

[0037] In this embodiment, see Figure 1 Preferably, the axis of the metal rod 1 is vertically oriented, but it can also be slightly inclined, meaning the angle between the central axis of the metal rod 1 and the vertical is 0–30°. This facilitates the formation of molten metal droplets at the melting end of the metal rod 1, allowing them to fall. Furthermore, the melting end of the metal rod 1 has a pointed tip that gradually tapers from top to bottom. The emission convergence point of the plasma spray gun 6 is located at this pointed tip, which can be conical or other suitable shapes. This allows the molten metal to better converge at the tip and form a liquid flow.

[0038] In this embodiment, see Figure 1 As a preferred design, the plasma spray gun 6 is tilted, with the ejected plasma jet tilted downwards. The direction of the plasma jet spray is at an appropriate angle to the axis of the metal rod 1, preferably 15-50°. This allows the plasma jet to heat the molten working end of the metal rod 1 while simultaneously blowing the molten metal downwards, better atomizing the molten metal. The falling molten metal is also heated by the plasma jet after leaving the metal rod 1, preventing premature solidification of the molten metal droplets. Multiple plasma spray guns 6 are arranged at intervals along the circumference of the metal rod 1, preferably evenly distributed. More preferably, the plasma device also includes a spray gun connecting mechanism 7, which is connected to the plasma spray gun 6. This mechanism allows adjustment of the vertical and horizontal positions of the plasma spray gun 6, as well as the spray tilt angle, making it more convenient and flexible to use and adaptable to various working conditions.

[0039] In this embodiment, see Figure 1 As a preferred design, the airflow nozzles 8 are also inclined, with the airflow directed downwards. The spray direction of the airflow nozzles 8 has an appropriate angle with the axis of the metal rod 1, preferably 15-50°, so that the airflow can effectively sweep the falling droplets downwards. Multiple airflow nozzles 8 are arranged at intervals along the circumference of the metal rod 1 and are staggered from the plasma gun 6, thereby reducing the mutual influence between the high-pressure airflow and the plasma jet. The high-pressure airflow from the multiple airflow nozzles 8 mainly converges at an appropriate position below the tip of the metal rod 1. While a small portion of the high-pressure airflow from the nozzles 8 can also sweep the tip of the metal rod 1, it should not excessively affect the operation of the plasma jet. In this embodiment, when the molten metal dripping from the tip of the metal rod 1 falls to a distance of 5cm-30cm, it is atomized into fine metal droplets under the combined action of the plasma jet and the high-speed airflow. The airflow nozzles 8 are detachably mounted on the side wall of the atomization chamber 3 and can be replaced as needed.

[0040] In this embodiment, see Figure 1 As a preferred design, the induction coil 2 is a conical coil that gradually decreases in size along the direction from the outer end to the inner end (the end where the melting working end is located) of the metal rod 1. This helps to generate a gradient magnetic field, thereby making the magnetic field more concentrated, reducing energy loss, and lowering system energy consumption. It also helps with heat dissipation, preventing the coil from overheating and ensuring stable operation of the equipment over a long period of time.

[0041] In this embodiment, see Figure 1 As a preferred design, the atomizing chamber 3 is connected to the lower end of the heating chamber 5, and a partition 4 is installed between them for separation. The partition 4 has a through hole in the middle as a connecting channel 41 between the heating chamber 5 and the atomizing chamber 3. A protective plate is installed on one side of the partition 4 of the atomizing chamber 3. The protective plate is made of the same material as the metal rod 1. The protective plate can be integrated with the partition 4, that is, the entire partition 4 is made of the same material as the metal rod 1. Alternatively, the protective plate can be a separate plate from the partition 4 and fixedly connected to the partition 4. The protective plate, which is made of the same material as the metal rod 1, can prevent the high-temperature plasma from corroding the partition 4 and introducing impurities.

[0042] This invention also provides a method for preparing metal powder using a combination of electrode induction and plasma, employing the aforementioned metal powder preparation equipment, and comprising the following steps:

[0043] S1. Preheating: First, a certain vacuum degree is drawn into the heating chamber 5 and the atomizing chamber 3, preferably 7×10. ～3 The pressure is below Pa, and then an inert gas is introduced to prevent the metal from being oxidized. Induction coil 2 operates in heating chamber 5 to initially heat metal rod 1 to a specified temperature, which is lower than the melting point Tm of metal rod 1, preferably 0.6Tm to 0.9Tm. In this embodiment, preferably, the driving device simultaneously drives metal rod 1 to rotate at a speed of 5000 to 10000 rpm during heating to improve the heating effect. After heating metal rod 1 to 0.6Tm to 0.9Tm, the driving device moves metal rod 1 axially into atomization chamber 3, bringing the melting end of metal rod 1 to the atomization position in atomization chamber 3, ready for atomization.

[0044] S2. Atomization: The melting working end of the metal rod 1 is in the atomization working position in the atomization chamber 3. The driving device drives the metal rod 1 to rotate, preferably at a speed of 5000-10000 rpm. The induction coil 2 maintains a heating state, keeping the portion of the metal rod 1 within the induction coil 2 at 0.6Tm-0.9Tm. The plasma spray gun 6 sprays a plasma jet onto the melting working end of the metal rod 1, further heating the melting working end to the melting temperature. The airflow nozzle 8 blows a high-pressure airflow downwards from the melting working end. During continuous operation, the melting working end of the metal rod 1 is continuously consumed. While driving the metal rod 1 to rotate, the driving device maintains a certain axial movement speed, i.e., a certain feed speed, so that the melting working end of the metal rod 1 remains in the atomization working position. During atomization, since the metal rod 1 has been initially heated to 0.6Tm to 0.9Tm by the induction coil 2, the plasma spray gun 6 can quickly heat the metal to the melting temperature, thereby enhancing the heat source and achieving atomization. This heating method can also enable the highly conductive metal rod 1 to be rapidly heated to a stable melting point in the atomization chamber 3.

[0045] As can be seen from the above, the metal powder production equipment and method of the present invention have the following advantages;

[0046] The metal rod 1 is preheated to a specified temperature before entering the atomization chamber 3 by the heating chamber 5 and the induction coil 2. Then, the plasma jet is used as an additional heat source to rapidly and further heat the metal rod 1 in the atomization chamber 3 to the melting temperature. This allows the metal rod 1 to be heated to the melting temperature quickly and stably, especially for high-conductivity, high-melting-point metal rods. The plasma jet has an atomizing effect while heating, and together with the high-pressure airflow from the airflow nozzle 8, the molten metal liquid is atomized. The medium-speed rotation of the metal rod 1 improves the stability of atomization and the fine powder rate. Compared with traditional EIGA, it can effectively improve the powder production efficiency and the yield of metal powder. The powder produced has the advantages of being pollution-free, highly pure, having good sphericity, high fine powder rate, and fewer satellite powders and hollow powders.

[0047] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0048] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A metal powder fabrication apparatus combining electrode induction and plasma, comprising a metal rod (1), an induction coil (2), an atomizing chamber (3), and an airflow nozzle (8), characterized in that: It also includes a driving device, a plasma device and a heating chamber (5). A connecting channel (41) is provided between the heating chamber (5) and the atomizing chamber (3). The induction coil (2) is set in the heating chamber (5). The metal rod (1) extends into the induction coil (2). The driving device is connected to the metal rod (1) and can drive the metal rod (1) to rotate around its own central axis. At the same time, it can drive the metal rod (1) to move along its axial direction and extend into the atomizing chamber (3) through the connecting channel (41). The inner end of the metal rod (1) extending into the atomizing chamber (3) is the melting working end. The plasma device includes several plasma spray guns (6). The plasma spray guns (6) can spray plasma jets onto the melting working end of the metal rod (1) located in the atomizing chamber (3). The airflow nozzle (8) can blow airflow below the melting working end of the metal rod (1) located in the atomizing chamber (3).

2. The metal powder manufacturing equipment according to claim 1, characterized in that: The angle between the central axis of the metal rod (1) and the vertical direction is 0 to 30°.

3. The metal powder manufacturing equipment according to claim 2, characterized in that: The melting working end of the metal rod (1) has a pointed tip that gradually decreases in size from top to bottom.

4. The metal powder manufacturing equipment according to claim 2, characterized in that: The plasma gun (6) is tilted, and the ejected plasma jet is tilted downward.

5. The metal powder manufacturing equipment according to claim 1 or 4, characterized in that: There are multiple plasma spray guns (6), which are spaced apart circumferentially along the metal rod (1).

6. The metal powder manufacturing equipment according to claim 5, characterized in that: The airflow nozzles (8) are multiple and are spaced apart along the circumference of the metal rod (1), and are staggered from the plasma spray gun (6).

7. The metal powder manufacturing equipment according to claim 1, characterized in that: The induction coil (2) is a conical coil, and it gradually decreases in size along the direction from the outer end to the inner end of the metal rod (1).

8. A method for preparing metal powder using a combination of electrode induction and plasma, characterized in that: The metal powder is produced using the equipment described in claim 1, comprising the following steps: S1. Preheating: The induction coil (2) operates in the heating chamber (5) to preheat the metal rod (1) to a specified temperature, which is lower than the melting point temperature Tm of the metal rod (1); S2, Atomization: The melting working end of the metal rod (1) is in the atomization working position in the atomization chamber (3). The driving device drives the metal rod (1) to rotate, the induction coil (2) maintains the heating working state, the plasma spray gun (6) sprays plasma jets onto the melting working end of the metal rod (1), and further heats the melting working end to the melting temperature. The airflow nozzle (8) blows airflow below the melting working end.

9. The method for preparing metal powder according to claim 8, characterized in that: In step S1, the induction coil (2) heats the metal rod (1) to 0.6Tm to 0.9Tm.

10. The method for preparing metal powder according to claim 8, characterized in that: In step S2, the metal rod (1) rotates at a speed of 5000 to 10000 revolutions per minute.

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