Preparation device and preparation method of aluminum alloy spherical powder

Abstract

The invention relates to the technical field of powder metallurgy, in particular to a preparation device and method for aluminum alloy spherical powder. The preparation device comprises a smelting assembly, a control valve, a tundish and a feeding assembly which are all arranged in a smelting furnace body protected by vacuum or argon. During use, aluminum alloy raw materials are added into the smelting crucible through the feeding assembly, and the aluminum alloy raw materials in the smelting crucible are heated through the heating unit to form molten liquid. And the molten liquid flows into the tundish through the drainage pipe and then is subjected to subsequent atomization treatment to form the aluminum alloy spherical powder. Under the vacuum condition, materials are continuously added into the smelting crucible, so that the forming speed and the consumption speed of melt in the smelting crucible are the same, continuous operation can be achieved, the production efficiency and the batch consistency are greatly improved, the oxygen content of the powder is controlled within 500 ppm, high-quality spherical powder is prepared at low cost, and remarkable economic benefits and wide application are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of powder metallurgy, and in particular to a device and method for preparing spherical aluminum alloy powder. Background Art

[0002] Aluminum alloy spherical powder is a high-quality, high-performance metal powder material widely used in a wide range of fields, including aviation, aerospace, automotive, machinery, and medical applications. Vacuum induction melting gas atomization (VIGA) is one of the primary methods for preparing low-oxygen, high-quality aluminum alloy spherical powder. The main process involves melting metal or metal alloy round bars of a certain size under vacuum conditions. Under gas protection, the molten metal is poured from a melting crucible into a tundish, flowing downward through a guide nozzle at the bottom of the tundish. High-pressure airflow through the nozzle atomizes the molten metal into a large number of fine droplets, which solidify into spherical or near-spherical particles during operation, achieving the desired powder production.

[0003] Existing methods for preparing spherical aluminum alloy powders suffer from several issues. First, production efficiency is low and batch size is a serious problem. The VIGA aluminum alloy preparation process is complex and lengthy: loading—closing the furnace door—evacuating the equipment—melting—atomizing and powdering—venting—opening the furnace door—cleaning the crucible (for oxide inclusions adhering to the crucible wall)—cleaning the tundish (for oxide inclusions adhering to the crucible)—replacing the draft tube (residual oxide inclusions and solidified metal inside the draft tube require treatment before reuse)—reloading the material again. This process repeats itself, with each cycle representing a production heat. This long production cycle means that only one batch can be melted and processed at a time, and the crucible must be reloaded for the next batch. This results in low production efficiency and poor batch consistency. Secondly, the existing aerosol equipment used to produce aluminum alloy spherical powder includes 50kg, 100kg, 200kg and 500kg classes. That is, the production capacity can be increased by increasing the amount of metal materials smelted in a single batch, but the capacity of the equipment cannot be increased indefinitely. The single metal liquid is too large, especially the highly active aluminum alloy liquid. The process has major safety hazards and the equipment investment is large, the flexibility is low, and the maintenance cost each time is too high. Therefore, the current mainstream aerosol equipment is still in the 50-200kg class, so its production capacity is difficult to meet the needs of large-scale industrial applications (such as solar slurry, high-end metal paint, powder metallurgy and other 100,000-ton application scales). Summary of the Invention

[0004] In view of the above-mentioned defects, the technical problem to be solved by the present invention is to provide a device and method for preparing aluminum alloy spherical powder so that the production of aluminum alloy spherical powder can be carried out continuously and the production efficiency can be improved.

[0005] The above technical objectives of the present invention are achieved through the following technical solutions: In one aspect, a device for preparing aluminum alloy spherical powder is provided, comprising: A smelting assembly, comprising a smelting crucible, a first heating unit, and a drainage tube, wherein the first heating unit is disposed on the smelting crucible, and the drainage tube is in communication with a lower portion of the smelting crucible; a control valve, the control valve being arranged on the drainage tube; a tundish, the tundish being disposed below the draft tube, the inlet of the tundish corresponding to the outlet of the draft tube; A feeding assembly, the feeding assembly being arranged above the melting crucible, the outlet of the feeding assembly corresponding to the inlet of the melting crucible; A smelting chamber furnace body, wherein the smelting chamber furnace body is connected to the vacuum system, the smelting assembly, the feeding assembly and the tundish are all arranged inside the smelting chamber furnace body, and the inlet of the feeding assembly and the outlet of the tundish both extend outside the smelting chamber furnace body; By adopting the above scheme, in the initial state, the control valve is closed and the inside of the drainage tube cannot circulate. During use, the aluminum alloy raw material is added to the melting crucible through the feeding assembly, and the aluminum alloy raw material in the melting crucible is heated by the heating unit, and the aluminum alloy raw material is heated to melt to form a melt. The control valve is opened, and the melt in the melting crucible flows into the tundish through the drainage tube, and then a subsequent atomization treatment is performed to form an aluminum alloy spherical powder. In the production process of aluminum alloy spherical powder, the molten aluminum alloy melt in the melting crucible does not need to be poured into the tundish, but flows directly into the tundish through the drainage tube. There is no need to melt one furnace of aluminum alloy raw materials and then melt the next furnace of aluminum alloy raw materials, which effectively improves production efficiency. On the other hand, under vacuum / argon protection (evacuating and then filling with argon protection) conditions, material is continuously added to the melting crucible to keep the liquid level of the melt in the melting crucible at a certain height (the static pressure head remains unchanged to ensure that the metal liquid flow rate of the atomizing guide tube tends to a certain value), so that the formation rate and consumption rate of the melt in the melting crucible are the same, and continuous operation can be achieved, which greatly improves production efficiency and batch consistency, controls the oxygen content of the powder within 500ppm, and prepares high-quality spherical powder at a low cost, has significant economic benefits and is widely used.

[0006] In addition, by evacuating the melting chamber furnace body, the aluminum alloy can be smelted in a vacuum environment, preventing impurities in the air from entering and improving the smelting quality.

[0007] The feeding assembly includes a first feeding bin and a motor. The top of the first feeding bin is provided with a feed port, and the bottom is provided with a discharge port. The discharge port corresponds to the smelting crucible. The motor is arranged on the first feeding bin. A conveying shaft is rotatably connected to the first feeding bin. The conveying shaft is arranged vertically. The output shaft of the motor is fixedly connected to the conveying shaft. The conveying shaft is provided with a spiral blade, and the spiral blade matches the first feeding bin. When feeding the smelting crucible through the feeding assembly, the aluminum alloy raw material is added through the feed port, and then the conveying shaft is driven to rotate by the motor, thereby driving the spiral blade to rotate. The rotation of the spiral blade drives the aluminum alloy raw material to be uniformly fed into the smelting crucible, thereby achieving the effect of uniform and stable feeding. And because the conveying shaft is arranged vertically, the feeding direction is longitudinal. Compared with the horizontal or inclined setting, it helps to feed smoothly and reduce the occurrence of blockage.

[0008] The feed port is connected to a second feeding silo, which has a feed port at its top and three doors within it. The three doors separate the interior of the second feeding silo into an upper silo and a lower silo. The upper silo is connected to a second vacuum-pumping pipe, which is equipped with a second vacuum-tight valve. During use, the door at the top of the upper silo is opened, allowing the aluminum alloy raw material to enter the upper silo, and then the door at the top of the upper silo is closed. The second vacuum-tight valve is opened, and a vacuum pump is used to evacuate the upper silo through the second vacuum-pumping pipe. After the upper silo is evacuated, the door at the bottom of the upper silo is opened, allowing the aluminum alloy raw material to fall into the lower silo, and then the door at the bottom of the upper silo is closed. The door at the bottom of the lower silo is then opened, allowing the aluminum alloy raw material to enter the first feeding silo, and then the door at the bottom of the lower silo is closed. Since it takes a certain amount of time for all the aluminum alloy raw materials in the lower bin to be fed into the melting crucible through the feeding assembly, during this time, the aluminum alloy raw materials are added to the upper bin, and then the upper bin is evacuated before the bin door at the bottom of the upper bin is opened to allow the aluminum alloy raw materials to enter the lower bin, thereby maintaining a continuous supply of aluminum alloy raw materials in the lower bin. This allows for continuous feeding of aluminum alloy raw materials and prevents air from being introduced into the melting chamber during feeding, thus ensuring a vacuum environment inside the melting chamber.

[0009] The present invention is further configured such that the smelting chamber furnace body is connected to a first vacuum pumping pipe, and the first vacuum pumping pipe is provided with a first vacuum sealing valve. The first vacuum pumping pipe can facilitate vacuuming of the interior of the smelting furnace body.

[0010] The present invention further provides that one end of the drainage tube communicating with the smelting crucible is threadedly connected to the smelting crucible. This threaded connection facilitates installation and removal of the drainage tube and also improves the sealing of the connection between the drainage tube and the smelting crucible, preventing leakage.

[0011] The present invention is further configured such that a second heating unit is provided on the drainage tube. The second heating unit can heat the melt in the drainage tube to prevent the melt from cooling and condensing too quickly due to a temperature drop in the drainage tube, thereby preventing the drainage tube from being blocked.

[0012] The present invention further provides that the control valve includes a liquid guide tube and a stopper rod. The end of the liquid guide tube remote from the melting crucible is connected to a side of the liquid guide tube. The stopper rod is disposed within the liquid guide tube and matches the inner diameter of the liquid guide tube. The outlet of the liquid guide tube corresponds to the inlet of the melting crucible. By adjusting the position of the stopper rod within the liquid guide tube, the cross-sectional area of ​​the connection between the liquid guide tube and the liquid guide tube, available for molten metal to flow, is adjusted, thereby controlling the flow rate of the molten metal.

[0013] The control valve further includes a linear drive unit disposed above the catheter tube and configured to drive the stopper rod to move axially along the catheter tube. The linear drive unit can be used to conveniently drive the stopper rod to adjust its position within the catheter tube, thereby facilitating flow control.

[0014] The present invention is further configured such that the inclination angle of the spiral blade is 45-60°, which facilitates smooth material dropping; the distance between the discharge port at the bottom of the first feeding bin and the liquid level in the melting crucible is 5-10 cm. At this distance, when the raw material falling from the discharge port at the bottom of the first feeding bin falls into the melting crucible, it can reduce the outward splashing of the solution in the melting crucible, which on the one hand reduces the waste of raw materials and saves costs, and on the other hand helps to keep the interior of the melting chamber furnace clean and tidy.

[0015] On the other hand, a method for preparing aluminum alloy spherical powder is also provided, wherein the aluminum alloy spherical powder is prepared using the above-mentioned aluminum alloy spherical powder preparation device, comprising the following steps: S1: Add aluminum alloy raw materials into the melting crucible through the feeding assembly; S2: The interior of the melting chamber is evacuated and then filled with argon gas; S3: The first heating unit and the tundish start heating, and the aluminum alloy raw material in the melting crucible is heated by the first heating unit until it melts to form a melt; S4: Open the control valve and the melt flows into the tundish through the drainage pipe; S5: After the molten liquid in the smelting crucible flows into the tundish, the molten liquid at the bottom outlet of the tundish is impact-atomized and broken into droplets, which are then spheroidized, solidified, and cooled to form powder particles; S6: Adjust the feeding rate, melting rate and atomization rate of the aluminum alloy raw material to be consistent.

[0016] The present invention is further configured such that the feeding rate, the melting rate and the rate of atomizing the melt are 60-1200 kg / h.

[0017] The present invention is further configured such that the aluminum alloy raw material is an irregular block material of 3-10 cm; The rotation speed of the motor (402) is 5RPM-135RPM; The pressure in the smelting chamber furnace body (5) is 5-45 kPa; The temperature of the solution in the smelting crucible (101) is 800-900°C; The liquid level in the smelting crucible (101) is 800-1000 mm; The diameter of the draft tube at the bottom of the tundish (3) is 2-8 mm; The temperature of the solution in the tundish (3) is 850-950°C; The liquid level in the tundish (3) is 250-300 mm.

[0018] Through the above technical solution: The aluminum alloy raw material is an irregular block material of 3-10 cm. The raw material does not need to be finely processed into metal or metal alloy round bars, which greatly saves costs and has significant economic benefits.

[0019] For irregular bulk aluminum alloy raw materials, in order to adjust the feeding rate, melting rate and atomization rate of the melt to be consistent and fall within 60-1200kg / h, multiple experiments and adjustments were carried out to obtain specific parameters in each step. Based on the powder property data, the optimal rate range was determined to be 60-1200kg / h, with a wide adjustment range and wide application. The specific rate value mainly depends on the powder application requirements. For example, if 3D printing requires 20-65μm powder, the atomization pressure can be adjusted to make the D50 of the powder 40μm±5μm; if it is for MIM purposes, the melting efficiency and atomization efficiency can be reduced by adjusting the parameter values ​​of the melting crucible and the tundish, and the pressure can be controlled to make the powder particle size as close to 5-25μm as possible, and so on.

[0020] The control valve opening is mainly used as an adjustment mechanism for the smooth progress of the atomization production process. It controls the flow rate of the aluminum alloy liquid and plays a role in transition control between the feed speed and the atomization speed.

[0021] Matching the tundish liquid level with the atomization rate: The operator observes the tundish liquid level through an observation window and adjusts the control valve to ensure it remains stable. Specifically, the tundish liquid level is maintained at 250-300mm, corresponding to a solution volume of 4 / 5-3 / 4 of the tundish volume. The control valve is designed for stepless adjustment and features a graduated scale with 20 large scale lines / shifts (5% each) with a rapid response, corresponding to a flow rate of 1-20kg / min (corresponding to the atomization pulverization rate, which is primarily determined by the diameter of the draft tube at the bottom of the tundish and the positive pressure in the smelting chamber). Each time the furnace is reopened for smelting and atomizing powder production, after the first mouthful of molten aluminum is poured into the tundish, in order to quickly fill the tundish with the molten aluminum, a larger gear will be used at the beginning (for example, if the aperture of the draft pipe at the bottom of the tundish is 4mm, the argon positive pressure in the smelting chamber is 15KPa, and the atomization efficiency is 6kg / min, then the gear may be opened to the 10th gear, that is, the 10kg / min gear at the beginning). After the tundish liquid level reaches more than 3 / 4 of its height, the gear is adjusted to the 6th gear (6kg / min). At the same time, the production personnel continue to observe whether the liquid level in the tundish continues to rise (or fall). If the liquid level stabilizes, the gear is maintained.

[0022] Once the tundish atomization system is blocked, turn off the control valve and the feeding system (stop feeding). If necessary, the first heating unit can be selected to keep the power on for melting the crucible, but the heating power should be lowered to only keep the aluminum liquid warm, so as to avoid the aluminum liquid from continuing to heat up and overheating, because the aluminum liquid is no longer continuously flowing out of the atomization.

[0023] Feed rate control: This is consistent with the atomization speed. To avoid the risk of liquid overflow, a liquid level sensor is installed in the crucible. The motor is electrically connected and linked to the liquid level sensor. When feeding is enabled, the motor starts when the crucible liquid level falls below a specified value and stops when it rises above. The feed rate is actually controlled by the speed of the 402 drive motor. The faster the drive motor speed, the faster the feed rate. The drive motor speed ranges from 5RPM to 135RPM, corresponding to the corresponding feed rate.

[0024] In summary, the device and method for preparing aluminum alloy spherical powder provided by the present invention have at least the following beneficial effects: 1. The overall innovation of the device is that the three steps of feeding, melting and atomization are systematically coordinated. There is no need to stop the machine for feeding during the production process. Continuous feeding and melting can be carried out to continuously prepare aluminum alloy spherical powder, which increases production capacity and significantly reduces production costs.

[0025] 2. During the feeding and smelting process, secondary vacuuming is carried out, and the smelting furnace body has a good vacuum environment, which can prevent impurities in the air from entering, improving and ensuring the smelting quality; and the tundish has the function of filtering and removing impurities, further improving the quality of the final powder product.

[0026] 4. The aluminum alloy raw material is an irregular block of 3-10 cm. The source of the raw material does not need to be refined into metal or metal alloy round bars, which greatly saves the cost of raw materials. In this application, argon gas will be used in a vacuum environment. The argon gas can be recycled, and only about 2 kWh of electricity is required for melting and atomizing pulverizing 1 kg of raw material, which greatly saves the cost of the production process.

[0027] 5. The feeding rate, melting rate and atomization rate of the melt are consistent and fall within 60-1200 kg / h, with a wide adjustment range and a wide range of applications, such as 3D printing and MIM. The final product powder has good properties, achieving low-cost high-quality output and significant economic benefits.

[0028] 6. Optimize the parameter settings and adjustment range in each step to achieve a controllable rate within 60-1200kg / h. BRIEF DESCRIPTION OF THE DRAWINGS In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without expending any novel work.

[0029] Figure 1 This is a schematic diagram of the structure of the present invention (the melting chamber furnace body is hidden); Figure 2 Is a schematic diagram of the overall structure of the present invention; Figure 3 is a morphology diagram of the AlSi10Mg aluminum alloy powder in Example 10 of the present application; Figure 4 is a morphology diagram of the AlSi10Mg aluminum alloy powder in Example 11 of the present application; Figure 5 yes Figure 4 A partial enlarged view of Figure 6 This is a morphology diagram of the AlSi10Mg aluminum alloy powder in Example 12 of the present application.

[0030] The reference numerals include: smelting assembly 1, smelting crucible 101, first heating unit 102, drainage tube 103, control valve 2, liquid guide tube 201, stopper rod 202, tundish 3, feeding assembly 4, first feeding bin 401, motor 402, conveying shaft 403, spiral blade 404, second feeding bin 405, bin door 406, upper bin 407, lower bin 408, second vacuum pipe 409, second vacuum-tight valve 410, smelting chamber furnace body 5, first vacuum pipe 6, first vacuum-tight valve 7, second heating unit 8, thermocouple 9. DETAILED DESCRIPTION

[0031] In order to make those skilled in the art better understand the technical solution of the present invention, Figure 1-6 The present invention is further described in detail with specific embodiments.

[0032] Example 1 See also Figure 1-2 This embodiment provides an apparatus for producing spherical aluminum alloy powder, comprising a smelting assembly 1, a control valve 2, a tundish 3, a feed assembly 4, and a smelting chamber furnace 5. The smelting assembly 1 includes a smelting crucible 101, a first heating unit 102, and a draft tube 103. The first heating unit 102 is disposed above the smelting crucible 101, and the draft tube 103 is connected to the lower portion of the smelting crucible 101. The control valve 2 is disposed on the draft tube 103. Specifically, the first heating unit 102 can employ an induction heating coil as known in the art. The tundish 3 is disposed below the draft tube 103, with its inlet corresponding to the outlet of the draft tube 103. The feed assembly 4 is disposed above the smelting crucible 101, with its outlet corresponding to the inlet of the smelting crucible 101. The smelting assembly 1 , the feeding assembly 4 and the tundish 3 are all arranged in the smelting chamber furnace body 5 , and the inlet of the feeding assembly 4 and the outlet of the tundish 3 both extend to the outside of the smelting chamber furnace body 5 .

[0033] By adopting the above scheme, in the initial state, the control valve 2 is closed, and the inside of the flow guide pipe 103 cannot flow. In use, the aluminum alloy raw material is added into the smelting crucible 101 through the feeding assembly 4, and the smelting chamber furnace body 5 is subjected to vacuumizing treatment. The aluminum alloy raw material in the smelting crucible 101 is heated by the heating unit, and the aluminum alloy raw material is heated to be melted to form a molten liquid. The control valve 2 is opened, and the molten liquid in the smelting crucible 101 flows into the tundish 3 through the flow guide pipe 103, and then subsequent atomization treatment is performed to form aluminum alloy spherical powder. In the production process of the aluminum alloy spherical powder, the molten aluminum alloy molten liquid in the smelting crucible 101 does not need to be poured into the tundish 3, but directly flows into the tundish 3 through the flow guide pipe 103, and the smelting of one batch of aluminum alloy raw material is not needed for the smelting of the next batch of aluminum alloy raw material, thereby effectively improving the production efficiency. On the other hand, the smelting crucible 101 is continuously fed, and the liquid level of the molten liquid in the smelting crucible 101 can be maintained at a height, so that the preparation of the aluminum alloy spherical powder can be continuously operated, and the production efficiency is greatly improved.

[0034] In order to facilitate the vacuumizing of the inside of the smelting chamber furnace body 5, further, the smelting chamber furnace body 5 is communicated with a first vacuumizing pipe 6, and the first vacuumizing pipe 6 is provided with a first vacuum sealing valve 7.

[0035] The end of the flow guide pipe 103 communicated with the smelting crucible 101 is threadedly connected with the smelting crucible 101. Specifically, the left end of the flow guide pipe 103 is provided with an external thread, the right side of the smelting crucible 101 is provided with a threaded hole, and the left end of the flow guide pipe 103 is threadedly connected in the threaded hole. In the embodiment, the flow guide pipe 103 is preferably made of graphite material.

[0036] In order to prevent the molten liquid of the aluminum alloy from being cooled to form an obstruction in the flow guide pipe 103, the flow guide pipe 103 is provided with a second heating unit 8, and the aluminum alloy molten liquid in the flow guide pipe 103 is heated by the second heating unit 8. The second heating unit 8 can be an inductive heating coil in the prior art.

[0037] In some embodiments, the feeding assembly 4 includes a first feeding bin 401 and a motor 402. The first feeding bin 401 has an inlet at the top and an outlet at the bottom, which corresponds to the smelting crucible 101. The motor 402 is mounted on the first feeding bin 401, specifically located on the top and outside of the first feeding bin 401. A conveyor shaft 403 is rotatably connected to the first feeding bin 401. The conveyor shaft 403 is vertically arranged, and the output shaft of the motor 402 is fixedly connected to the conveyor shaft 403. The conveyor shaft 403 is provided with a spiral blade 404, which mates with the first feeding bin 401. The inclination angle of the spiral blade 404 is 45-60°, which helps to smoothly drop the material. The distance between the discharge port at the bottom of the first feeding bin 401 and the liquid level in the melting crucible 101 is 5-10 cm. Within this distance range, when the raw materials falling from the discharge port at the bottom of the first feeding bin fall into the melting crucible, it can reduce the splashing of the solution in the melting crucible. On the one hand, it reduces the waste of raw materials and saves costs. On the other hand, it helps to keep the melting chamber furnace clean. In the embodiment of the present application, the inclination angle of the spiral blade 404 is 45°, and the distance between the discharge port at the bottom of the first feeding bin 401 and the liquid level in the melting crucible 101 is 5 cm. The first feeding bin 401 is generally in the shape of an inverted cylinder. The diameter of the spiral blade 404 matches the inner diameter of the first feeding bin 401, and the feed port is opened at an eccentric position at the top of the first feeding bin 401.

[0038] In order to prevent air from entering the first feeding bin 401 along with the aluminum alloy raw material when feeding into the first feeding bin 401, the feed port is further connected to the second feeding bin 405, and a feed port is opened on the top of the second feeding bin 405. Three bin doors 406 are provided in the second feeding bin 405, and the three bin doors 406 are distributed from top to bottom. The bin doors 406 can be opened and closed. When opened, the two spaces separated by the bin doors 406 can be connected, and when closed, the two spaces are separated. The three bin doors 406 separate the internal space of the second feeding bin 405 into an upper bin 407 and a lower bin 408. The upper bin 407 is connected to a second vacuum pipe 409, and the second vacuum pipe 409 is provided with a second vacuum sealing valve 410. When feeding, the feeding assembly 4 opens the door 406 at the top of the upper bin 407, allowing the aluminum alloy raw material to enter the upper bin 407, and then closes the door 406 at the top of the upper bin 407. The second vacuum sealing valve 410 is opened, and a vacuum pump is used to evacuate the upper bin 407 through the second vacuum pipe 409. After the upper bin 407 is evacuated, the door 406 at the bottom of the upper bin 407 is opened, allowing the aluminum alloy raw material to fall into the lower bin 408, and then closes the door 406 at the bottom of the upper bin 407. The door 406 at the bottom of the lower bin 408 is then opened, allowing the aluminum alloy raw material to enter the first feeding bin 401, and then closes the door 406 at the bottom of the lower bin 408. Since it takes a certain amount of time for the aluminum alloy raw material in the lower bin 408 to be completely fed into the melting crucible 101 through the feeding assembly 4, during this time, the aluminum alloy raw material is added to the upper bin 407. Then, after the upper bin 407 is evacuated, the bin door 406 at the bottom of the upper bin 407 is opened to allow the aluminum alloy raw material to enter the lower bin 408, thereby maintaining a continuous supply of aluminum alloy raw material in the lower bin 408. This allows for continuous feeding of the aluminum alloy raw material and prevents air from being introduced into the melting chamber furnace body 5 during feeding, thereby ensuring a vacuum environment within the melting chamber furnace body 5.

[0039] In order to ensure that the aluminum alloy raw material can smoothly enter the first feeding bin 401 from the second feeding bin 405, the lower half of the lower bin 408 is further inclined. After the bin door 406 at the bottom of the lower bin 408 is opened, the aluminum alloy raw material in the lower bin 408 can slide along the inclined portion of the lower half of the lower bin 408 into the first feeding bin 401. This can prevent the aluminum alloy raw material from entering the first feeding bin 401 from the second feeding bin 405 at too high a speed, thereby preventing a large impact on the spiral blade 404.

[0040] In some embodiments, the control valve 2 comprises a liquid guide pipe 201 and a plug rod 202, the end of the drainage pipe 103 away from the smelting crucible 101 communicates with the side of the liquid guide pipe 201, the plug rod 202 is arranged in the liquid guide pipe 201 and matches the inner diameter of the liquid guide pipe 201, and the outlet of the liquid guide pipe 201 corresponds to the inlet of the smelting crucible 101. Specifically, the drainage pipe 103 is arranged transversely, the liquid guide pipe 201 is arranged vertically, and the communication position of the drainage pipe 103 and the liquid guide pipe 201 is located at the middle part of the liquid guide pipe 201. The control valve 2 further comprises a linear drive unit arranged above the liquid guide pipe 201, which is used to drive the plug rod 202 to move along the axial direction of the liquid guide pipe 201. The liquid guide pipe 201 is preferably integrally formed with the drainage pipe 103, the plug rod 202 is specifically made of graphite material, and the linear drive unit is specifically an electric cylinder in the prior art.

[0041] In order to conveniently monitor the temperature of the molten liquid in the smelting crucible 101, further, a thermocouple 9 is arranged in the smelting crucible 101, which is used to monitor the temperature of the molten liquid in the smelting crucible 101. The thermocouple 9 specifically adopts an armored thermocouple 9 in the prior art.

[0042] Based on the same inventive concept, the application further provides a preparation method of aluminum alloy spherical powder, which is prepared by using the preparation device of aluminum alloy spherical powder described above, and comprises the following steps: S1: aluminum alloy raw materials are added into the smelting crucible 101 by the feeding assembly 4, the aluminum alloy raw materials are AlSi10Mg and irregular blocks with a size of 3-10 cm; S2: vacuumizing the smelting chamber furnace body 5; S3: the first heating unit 102 and the tundish 3 start heating, the aluminum alloy raw materials in the smelting crucible 101 are heated to molten liquid by the first heating unit 102, the power of the power supply of the first heating unit 102 is smelting power, the smelting power affects the smelting rate, and the smelting power in the embodiment of the application is 50 kW; S4: opening the control valve 2, and the molten liquid enters the tundish 3 through the drainage pipe 103; S5: after the molten liquid in the smelting crucible 101 flows into the tundish 3, the molten liquid at the outlet of the tundish 3 is subjected to atomization treatment; S6: adjusting the feeding rate of the aluminum alloy raw materials, the smelting rate and the rate of atomization treatment of the molten liquid to be consistent, and finally obtaining AlSi10Mg powder.

[0043] In step S6, specifically, the feeding rate of the aluminum alloy raw material can adjust the rotation speed of the motor 402 to adjust the feeding rate; the rate of the molten liquid into the tundish 3 can be adjusted by adjusting the flow of the flow guide pipe 103, so that the molten liquid flow is stable, uniform and controllable, and the molten liquid flow is determined according to the remaining capacity of the molten liquid in the crucible of the tundish 3.

[0044] The feeding rate, melting rate and atomization treatment rate of the molten liquid are 60-1200 kg / h, and the feeding rate in the embodiment of the application is 60 kg / h.

[0045] The pressure in the melting chamber furnace body 5 is 5-45 kPa, and the pressure in the melting chamber furnace body 5 in the embodiment of the application is 15 kPa. The temperature of the solution in the melting crucible 101 is 800-900℃, and the temperature of the solution in the melting crucible 101 in the embodiment of the application is 850℃. The liquid level height in the melting crucible 101 is 800-1000mm, and the liquid level height in the melting crucible 101 in the embodiment of the application is 900mm. The diameter of the flow guide pipe at the bottom of the tundish (3) is 2-8mm, and the diameter of the flow guide pipe 103 in the embodiment of the application is 4mm. The temperature of the solution in the tundish 3 is 850-950℃, and the temperature of the solution in the tundish 3 in the embodiment of the application is 876℃. The liquid level height in the tundish 3 is 250-300mm, and the liquid level height in the tundish 3 in the embodiment of the application is 270mm.

[0046] In addition, 1. Atomization speed control factor (under the premise that the temperature of the molten liquid is kept constant): Control method one: usually the diameter of the flow guide pipe at the bottom of the tundish (the pressure of the melting chamber is 15KPa)

[0047] Control method two: adjust the pressure of the melting chamber But in the case of constant diameter of the flow guide pipe, the atomization speed can also be adjusted by adjusting the pressure of the melting chamber (for example, the diameter of the flow guide pipe is 4mm):

[0048] According to production experience, as the diameter of the flow guide pipe increases, the pressure adjustment effect will be weakened.

[0049] 2. Matching the tundish liquid level with the atomization speed: The operator observes the tundish liquid level through the observation window and adjusts the control valve to ensure it remains within a stable range. Specifically, the tundish liquid level is controlled at 250-300mm, corresponding to a solution volume of 4 / 5-3 / 4 of the tundish volume. The control valve is designed for stepless adjustment and features a graduated scale with 20 large scale lines / shifts (5% each) and a fast response, corresponding to a flow rate of 1-20kg / min (corresponding to the atomization powder production rate). Each time the furnace is reopened for smelting and atomizing powder production, after the first mouthful of molten aluminum is poured into the tundish, a larger gear will be used at the beginning to quickly fill the tundish with the molten aluminum (for example, if the atomization efficiency is 6kg / min, then the gear may be opened to the 10th gear, that is, the 10kg / min gear). After the liquid level in the tundish reaches more than 3 / 4 of its height, the gear is adjusted to the 6th gear (6kg / min). At the same time, the production personnel continue to observe whether the liquid level in the tundish continues to rise (or fall). If the liquid level stabilizes, the gear is maintained.

[0050] Once the tundish atomization system is blocked, turn off the control valve and the feeding system (stop feeding). If necessary, the first heating unit can be selected to keep the power on for melting the crucible, but the heating power should be lowered to only keep the aluminum liquid warm, so as to avoid the aluminum liquid from continuing to heat up and overheating, because the aluminum liquid is no longer continuously flowing out of the atomization.

[0051] 3. Feed rate control: This is consistent with the atomization speed. To avoid the risk of liquid overflow, a liquid level sensor is installed in the crucible. The motor is electrically connected and linked to the liquid level sensor. When feeding is turned on, the motor starts when the liquid level in the crucible falls below a specified value and stops when it rises above the specified value. The feed rate is actually controlled by the speed of the 402 drive motor. The faster the drive motor speed, the faster the feed rate. The drive motor speed ranges from 5RPM to 135RPM, corresponding to the corresponding feed rate.

[0052] 4. Melting Speed ​​Control: To ensure the melting speed supports the continuous and normal atomization process according to the set atomization powder production rate (for example, 300kg / h), we often appropriately increase the melting power to ensure that the aluminum block material can be completely melted at the set feed rate, while also considering energy consumption and cost control. The melting is carried out by graphite crucible induction melting. The rated power of the medium-frequency induction power supply of the melting crucible melting system is 900kW, generally adjustable between 50kW and 800kW.

[0053]

[0054] Note: The melting rate here corresponds to the atomization rate mentioned above.

[0055] Example of calculating the theoretical power required for melting heating at the corresponding melting rate As an example, with a maximum atomization rate of 20 kg / min, a theoretical treatment is made here, which is to equate the atomization of 1200 kg / h of aluminum alloy while smelting to the melting of 1200 kg of aluminum alloy blocks completed in 45 min and obtaining a superheat of 200°C. That is, in order to calculate the inductive power required for the induction smelting of 1200 kg of aluminum alloy (heating from room temperature to melting point, complete melting and superheating by 200°C, time is 45 min) in a graphite crucible, the calculation is based on thermodynamic principles and takes into account the thermal physical parameters of aluminum alloy and the efficiency of induction smelting. Here are the detailed steps: ①. Key parameters and assumptions • Aluminum alloy properties (based on typical industrial aluminum alloys such as AlSi10Mg): Mass m = 1200 kg.

[0056] Initial temperature (room temperature) T initial = 25°C.

[0057] Melting point T melt = 660°C (aluminum alloy melting point range is usually 600-660°C, take the average).

[0058] Final temperature (after superheating) T final = T melt + 200°C = 860°C.

[0059] Solid specific heat capacity c s = 900 J / kg⋅K (from room temperature to melting point).

[0060] Liquid specific heat capacity c l = 1080 J / kg⋅K (from melting point to superheated state).

[0061] Latent heat of fusion L = 390,000 J / kg (phase change heat).

[0062] • Time requirement: melting and superheating process requires t = 0.75 hours.

[0063] Convert to seconds: t = 0.75 x 3600 = 2700 s (power calculation needs international units).

[0064] • Efficiency consideration: there is heat loss in induction smelting (such as radiation, convection, crucible heat loss, etc.). Typical efficiency η is 70-80% (take the middle value η=75%=0.75). Actual power needs to be adjusted based on efficiency.

[0065] Other assumptions: Heat loss is mainly reflected by the efficiency factor, and the crucible heat capacity is not calculated separately (graphite crucibles can be reused and the initial heat capacity is relatively small and can be ignored).

[0066] The power is calculated as average power (the induction generator needs to provide a constant average power throughout the process).

[0067] The aluminum alloy composition is not specified and the parameters are based on common industrial alloys; if a specific alloy type is used, the parameters may be adjusted.

[0068] ②. Total heat energy Q calculate The total heat energy consists of three parts: heating solid aluminum to the melting point, latent heat of fusion, and superheating liquid aluminum by 200°C. The formula is: Q = Q 1+ Q 2+ Q 3 in: · Q 1: Heat solid aluminum from 25°C to 660°C.

[0069] · Q 2: Latent heat of fusion.

[0070] · Q 3: Superheating liquid aluminum from 660°C to 860°C.

[0071] Step calculation: · Q 1 (sensible heat, solid state): Q 1= m × c s ×Δ T s =1200×900×(660−25) Δ T s =635K, Q 1=1200×900×635=1,080,000×635=685,800,000J · Q 2 (latent heat, melting): Q 2= m × L =1200×390,000=468,000,000J · Q3 (sensible heat, liquid superheat): Q 3= m × c l ×Δ T l =1200×1080×(860−660) Δ T l =200K, Q 3=1200×1080×200=1,296,000×200=259,200,000J ·total Q : Q =685,800,000+468,000,000+259,200,000=1,413,000,000J ③. Theoretical power P theory calculate Theoretical power is the power when there is no loss, using the formula: P theory = Q / t =1,413,000,000 / 2700≈523,333W=523.3kW ④. Actual power P actual Calculation (considering efficiency) Induction melting efficiency η =75%=0.75. The actual power is: P actual= P theory / η =523.3 / 0.75≈697.7kW Efficiency sensitivity: If the efficiency is different, the power needs to be adjusted: like η =70%, then P actual =523.3 / 0.7≈747.6kW.

[0072] like η =80%, then P actual =523.3 / 0.8≈654.2kW.

[0073] In step S6, after the aluminum alloy feed rate matches the rate of the atomized melt, the melt level in the tundish 3 is preferably maintained at a height of 250-300 mm. In the embodiment of the present application, the melt level in the tundish 3 is 270 mm. The amount of melt in the melting crucible 101 should be maintained at at least half of the maximum allowable capacity, and the amount of melt in the melting crucible 101 is preferably maintained at the maximum allowable capacity. In this embodiment, a 50 kg capacity melting crucible 101 is preferably used.

[0074] By adopting the above solution, the feed rate of the aluminum alloy raw material is consistent with the rate of atomization of the melt, which enables the atomization preparation of aluminum alloy spherical powder to operate stably. Continuous production improves production efficiency, and the safety factor of small-capacity melting crucibles is higher than that of large-capacity melting crucibles, reducing safety risks. The production equipment and preparation method of this embodiment increase the production efficiency by more than 11 times compared to traditional gas atomization equipment for 50kg-class aluminum alloy spherical powder.

[0075] Examples 2-9 The differences between Examples 2-9 and Example 1 are shown in Table 1: Table 1 Comparison table of Examples 1-9

[0076] In the Example Data Table, d10 represents the powder particle size corresponding to a cumulative volume fraction of 10%, d50 represents the powder particle size corresponding to a cumulative volume fraction of 50%, and d90 represents the powder particle size corresponding to a cumulative volume fraction of 90%. Referring to Table 1, it can be seen that in this application, by adjusting different atomization rates and adjusting various parameters to ensure that the feed rate, melting rate, and atomization rate are consistent, continuous production is achieved. The powder particle size can be adjusted to suit different powder applications, which has a wide range of applications.

[0077] Table 2 Chemical composition of the powder obtained in Example 8 (wt%)

[0078] Table 3 Chemical composition of the powder obtained in Example 9 (wt%)

[0079] Oxygen content is used to evaluate powder purity; lower oxygen content indicates higher powder purity. Referring to Tables 2 and 3, it can be seen that the application is able to produce aluminum alloy powder with a lower oxygen content. This is due to the application's incorporation of a secondary vacuum pumping structure and a secondary vacuum pumping process, which effectively prevents the ingress of airborne impurities. Furthermore, the tundish's filtering and impurity removal capabilities enable better impurity removal than existing technologies, effectively improving powder quality.

[0080] Table 4 Particle size distribution of the powder obtained in Example 8

[0081] Table 5 Particle size distribution of the powder obtained in Example 9

[0082] Table 6 Bulk density of the powder obtained in Example 8

[0083] Table 7 Bulk density of the powder obtained in Example 9

[0084] Table 8 Flowability of the powder obtained in Example 8

[0085] Table 9 Flowability of the powder obtained in Example 9

[0086] Example 10 This embodiment differs from Example 1 in that the atomization rate used in this embodiment is 1200 kg / h, the melting power is 800 kW, the diameter of the draft tube at the bottom of the tundish is 8 mm, the argon positive pressure in the melting chamber is the same at 15 kPa, and the atomization pressure is 5.5 MPa. The resulting atomized powder, after screening, has a particle size of 15-45 μm and is suitable for selective laser melting (SLM) additive manufacturing.

[0087] Example 11 This embodiment differs from Example 1 in that the atomization rate used in this embodiment is 120 kg / h, the melting power is 100 kW, the aperture of the draft tube at the bottom of the tundish is 2 mm, the argon positive pressure in the melting chamber is the same at 15 kPa, and the atomization pressure is 4.0 MPa. The resulting atomized powder, after screening, has a particle size of 0-25 μm and is used in the metal injection molding (MIM) process to manufacture aluminum alloy parts.

[0088] Example 12 This embodiment differs from Example 1 in that the atomization rate used in this embodiment is 1080 kg / h, the melting power is 700 kW, the diameter of the draft tube at the bottom of the tundish is 7 mm, the argon positive pressure in the melting chamber is the same at 15 kPa, and the atomization pressure is 5.0 MPa. The resulting atomized powder, after cyclone classification, has a particle size of 20-75 μm and is suitable for selective laser melting (SLM) additive manufacturing.

[0089] Reference Figure 3-6It can be seen that the AlSi10Mg aluminum alloy powder prepared in the present application has good sphericity and the powder surface is clearly visible, indicating that almost no impurities are coated and the prepared AlSi10Mg aluminum alloy powder has a low oxygen content.

[0090] In summary, the powder obtained in this application has excellent performance and can achieve continuous mass production, and high-quality metal powder can be prepared at low cost, which has significant economic value and wide application.

[0091] It should be noted that the words indicating direction in this article, such as up and down, are all based on Figure 1 The setting of the direction is only for the convenience of description and has no other specific meaning.

[0092] It should also be noted that, in this document, relational terms such as first and second, etc., are used solely to distinguish one entity or operation from another, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprise," "include," or any other variations thereof are intended to encompass non-exclusive inclusion, such that an article or device comprising a list of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such article or device. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not preclude the presence of additional identical elements in the article or device comprising the aforementioned elements.

[0093] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the core ideas of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from the principles of the present invention, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A device for preparing spherical aluminum alloy powder, characterized in that: include: The smelting assembly (1) is placed in a vacuum or argon protection chamber of a smelting chamber furnace body (5), the smelting assembly (1) comprising a smelting crucible (101), a first heating unit (102) and a drainage pipe (103), wherein the first heating unit (102) is arranged on the smelting crucible (101), and the drainage pipe (103) is connected to the lower part of the smelting crucible (101); A control valve (2), the control valve (2) being arranged on the drainage pipe (103); A tundish (3), the tundish (3) being arranged below the drainage tube (103), the inlet of the tundish (3) corresponding to the outlet of the drainage tube (103); A feeding assembly (4), the feeding assembly (4) being arranged above the melting crucible (101), the outlet of the feeding assembly (4) corresponding to the inlet of the melting crucible (101); A smelting chamber furnace body (5), wherein the smelting assembly (1), the feeding assembly (4) and the tundish (3) are all arranged in the smelting chamber furnace body (5), and the inlet of the feeding assembly (4) and the outlet of the tundish (3) both extend outside the smelting chamber furnace body (5); The feeding assembly (4) includes a first feeding bin (401) and a motor (402), the first feeding bin (401) is provided with a feeding port at the top and a discharging port at the bottom, the discharging port corresponding to the smelting crucible (101), the motor (402) is arranged on the first feeding bin (401), a conveying shaft (403) is rotatably connected in the first feeding bin (401), the conveying shaft (403) is arranged vertically, the output shaft of the motor (402) is fixedly connected to the conveying shaft (403), the conveying shaft (403) is provided with a spiral blade (404), and the spiral blade (404) matches the first feeding bin (401); The feed port is connected to a second feeding bin (405), a feeding port is provided on the top of the second feeding bin (405), three bin doors (406) are provided in the second feeding bin (405), and the three bin doors (406) divide the internal space of the second feeding bin (405) into an upper bin (407) and a lower bin (408), the upper bin (407) is connected to a second vacuum pumping pipe (409), and the second vacuum pumping pipe (409) is provided with a second vacuum sealing valve (410).

2. The device for preparing aluminum alloy spherical powder according to claim 1, characterized in that: The smelting chamber furnace body (5) is connected to a first vacuum pumping pipe (6), and a first vacuum sealing valve (7) is provided on the first vacuum pumping pipe (6).

3. The device for preparing aluminum alloy spherical powder according to claim 1, characterized in that: One end of the drainage tube (103) that is in communication with the smelting crucible (101) is threadedly connected to the smelting crucible (101).

4. The device for preparing aluminum alloy spherical powder according to any one of claims 1 to 3, characterized in that: A second heating unit (8) is provided on the drainage tube (103).

5. The device for preparing aluminum alloy spherical powder according to claim 1, characterized in that: The control valve (2) comprises a liquid guide tube (201) and a stopper rod (202); an end of the drainage tube (103) away from the smelting crucible (101) is connected to the side of the liquid guide tube (201); the stopper rod (202) is inserted into the liquid guide tube (201) and matches the inner diameter of the liquid guide tube (201); the outlet of the liquid guide tube (201) corresponds to the inlet of the smelting crucible (101); The control valve (2) further comprises a linear drive unit, which is arranged above the liquid guiding tube (201) and is used to drive the plug rod (202) to move axially along the liquid guiding tube (201).

6. The device for preparing aluminum alloy spherical powder according to claim 1, characterized in that: The inclination angle of the spiral blade (404) is 45-60 degrees; the distance between the discharge port at the bottom of the first feeding bin (401) and the liquid level in the smelting crucible (101) is 5-10 cm.

7. A method for preparing spherical aluminum alloy powder, characterized in that: The preparation of aluminum alloy spherical powder using the preparation device of any one of claims 1 to 6 comprises the following steps: S1: adding aluminum alloy raw materials into the melting crucible (101) through the feeding component (4); S2: Vacuuming the smelting chamber furnace body (5); S3: the first heating unit (102) and the tundish (3) start heating, and the aluminum alloy raw material in the melting crucible (101) is heated by the first heating unit (102) until it melts and forms a molten liquid; S4: Open the control valve (2), and the melt flows into the tundish (3) through the drainage pipe (103); S5: After the molten liquid in the smelting crucible (101) flows into the tundish (3), the molten liquid at the outlet of the tundish (3) is atomized; S6: Adjust the feeding rate, melting rate and atomization rate of the aluminum alloy raw material to be consistent.

8. The method for preparing spherical aluminum alloy powder according to claim 7, wherein: The feeding rate, melting rate and atomization rate of the melt are 60-1200 kg / h.

9. The method for preparing spherical aluminum alloy powder according to claim 7 or 8, characterized in that: The aluminum alloy raw material is an irregular block of 3-10 cm; The rotation speed of the motor (402) is 5RPM-135RPM; The pressure in the smelting chamber furnace body (5) is 5-45 kPa; The temperature of the solution in the smelting crucible (101) is 800-900°C; The liquid level in the smelting crucible (101) is 800-1000 mm; The diameter of the draft tube at the bottom of the tundish (3) is 2-8 mm; The temperature of the solution in the tundish (3) is 850-950°C; The liquid level in the tundish (3) is 250-300 mm.

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