CN118477996A - A method and device for processing irregular metal powder - Google Patents

Abstract

The present application discloses a method and device for processing irregular metal powder, which relates to the field of additive manufacturing technology and can re-spheroidize irregular metal powder. The scheme includes: the processing device includes: a spheroidizing chamber, the spheroidizing chamber includes a heat source structure, the heat source structure is used to form a heat source area, the heat source area is used to perform secondary spheroidization on the metal powder, and obtain the melting point of the metal powder and the critical pressure of the metal powder volatilization; determine the target pressure in the spheroidizing chamber according to the critical pressure, and determine the target temperature of the heat source area according to the melting point, and determine the target length range of the heat source area, the target length range is the distance range of the metal powder flowing through the heat source area; control the heat source structure to generate a heat source area with a target temperature and a target length range, and control the spheroidizing chamber to be under the target pressure, and control the metal powder to be added to the spheroidizing chamber and flow through the heat source area, so that the heat source area performs secondary spheroidization on the metal powder.

Description

A method and device for processing irregular metal powder

Technical Field

The present application relates to the field of additive manufacturing technology, and in particular to a method and device for processing irregular metal powder.

Background Art

The main preparation methods of spherical metal powder for additive manufacturing are gas atomization and plasma rotating electrode atomization. Although the gas atomization method has relatively low production costs and high fine powder yield, the presence of the reflow zone during the atomization process leads to a large amount of satellite powder in the prepared metal powder. When the plasma rotating electrode atomization method is used to prepare metals or alloys with low thermal conductivity, a large number of incompletely solidified particles collide with each other due to the slow cooling rate of the alloy, forming satellite powder and adhesion powder. In addition, when preparing some metal powders with low surface tension, when the molten metal leaves the end face of the bar in a "liquid line" manner, the surface tension makes it difficult for it to be quickly spheroidized in a short time, and "beaded" adhesion particles will be formed. Due to the relationship between the atomization mechanism and the equipment structure, it is difficult to effectively avoid the formation of irregular powders such as satellite powder and adhesion powder through process adjustment, and these irregular powders are difficult to separate in the subsequent screening process, which will directly affect the quality of additive manufacturing. Therefore, there is an urgent need for a method for re-spheroidizing the irregular powders formed in the process of preparing metal powders by atomization.

Summary of the invention

The present application provides a method and device for processing irregular metal powder, which can re-spheroidize the irregular metal powder, thereby improving the quality of additive manufacturing.

In order to achieve the above purpose, this application adopts the following technical solutions:

In a first aspect of an embodiment of the present application, a method for processing irregular metal powder is provided. The method is applied to a control device in a system for processing irregular metal powder. The system further includes a processing device, and the processing device includes: a spheroidizing chamber, wherein the spheroidizing chamber includes a heat source structure, wherein the heat source structure is used to form a heat source area, and the metal powder flows through the heat source area so that the heat source area performs secondary spheroidization on the metal powder. The method includes:

Obtaining the melting point of the metal powder and the critical pressure at which the metal powder volatilizes;

Determining a target pressure in the spheroidizing chamber according to the critical pressure, determining a target temperature of the heat source region according to the melting point, and determining a target length range of the heat source region, wherein the target length range is a distance range of the metal powder flowing through the heat source region;

The heat source structure is controlled to generate a heat source region with a target temperature and a target length range, and when the spheroidizing chamber is controlled to be at a target pressure, the metal powder is controlled to be added into the spheroidizing chamber and flow through the heat source region, so that the heat source region performs a secondary spheroidizing treatment on the metal powder.

As a possible implementation manner, determining the target length range of the heat source region includes:

The time required for the heat to reach the center of the metal powder sphere is determined based on the heat required for melting the adhesion between the two metal powders, the thermal conductivity of the metal powder, the initial temperature of the metal powder, the melting point of the metal powder, the preset radius of the metal powder, and the surface area of the metal powder;

Determining the movement distance of the metal powders in the heat source region when melting two adhering metal powders according to the required time and the preset gas flow rate;

The target length range of the heat source area is determined according to the movement distance.

As a possible implementation method, obtaining the heat required for melting the adhesion between two metal powders includes:

The heat required to melt the adhesion between two metal powders is determined based on the specific heat capacity, density, volume, initial temperature and melting point of the metal powders.

In a second aspect of an embodiment of the present application, there is provided a device for processing irregular metal powders, the device being located in a system for processing irregular metal powders, the system further comprising a control device;

The processing device comprises: a spheroidizing chamber, wherein the spheroidizing chamber comprises a heat source structure, wherein the heat source structure is used to form a heat source region, and the metal powder flows through the heat source region so that the heat source region performs a secondary spheroidizing treatment on the metal powder;

The control device is used to obtain the melting point of the metal powder and the critical pressure at which the metal powder volatilizes; determine the target pressure in the spheroidizing chamber according to the critical pressure, determine the target temperature of the heat source area according to the melting point, and determine the target length range of the heat source area, wherein the target length range is the distance range of the metal powder flowing through the heat source area; control the heat source structure to generate a heat source area with a target temperature and a target length range, and control the metal powder to be added into the spheroidizing chamber and flow through the heat source area when the spheroidizing chamber is under the target pressure, so that the heat source area performs secondary spheroidization on the metal powder.

As a possible implementation, the spheroidizing chamber further includes an ultrasonic device, and the ultrasonic wave generated by the ultrasonic device acts on the heat source area;

The heat source structure includes a plasma torch device, a microwave heating device or an induction heating device.

As a possible implementation, the top of the spheroidizing chamber of the processing device is connected to a material loading bin, the bottom of the spheroidizing chamber is connected to a material receiving bin, and the heat source area is located between the material loading bin and the material receiving bin;

The metal powder is added from the loading bin, flows through the heat source area and falls into the receiving bin.

As a possible implementation, the processing device further includes a vacuum system;

The control device is also used to control the vacuum system to perform vacuum treatment on the loading bin, the spheroidizing chamber and the receiving bin after the metal powder is added into the loading bin.

As a possible implementation, two first air inlet pipes are provided on two sides of the upper bin, and the tail of the first air inlet pipe forms an angle along the axial direction of the upper bin, and the angle ranges from 30 to 60 degrees, and inert gas is introduced into the air inlet pipe;

The first air inlet pipe is used to utilize the airflow in the pipe to disperse the metal powder entering the heat source area.

As a possible implementation, the spheroidizing chamber further includes a second air inlet pipe;

The control device is also used to introduce inert gas into the spheroidizing chamber from the second air inlet pipe after the spheroidizing chamber is vacuumized.

As a possible implementation manner, the spheroidizing chamber further includes a pressure detection device, and the pressure detection device is used to detect the gas pressure in the spheroidizing chamber.

The beneficial effects brought by the technical solution provided by the embodiment of the present application include at least:

The embodiment of the present application provides a method for processing irregular metal powders, which is applied to a control device in a processing system for irregular metal powders. The system also includes a processing device, which includes a spheroidizing chamber, and the spheroidizing chamber includes a heat source structure, the heat source structure is used to form a heat source area, and the metal powder flows through the heat source area so that the heat source area performs secondary spheroidization on the metal powder. In the specific processing process, the control device obtains the melting point of the metal powder and the critical pressure of the metal powder volatilization; determines the target pressure in the spheroidizing chamber according to the critical pressure, and determines the target temperature of the heat source area according to the melting point, and determines the target length range of the heat source area, and the target length range is the distance range of the metal powder flowing through the heat source area; controls the heat source structure to generate a heat source area with a target temperature and a target length range, and controls the spheroidizing chamber to be under the target pressure, and controls the metal powder to be added to the spheroidizing chamber and flow through the heat source area, so that the secondary spheroidization of the irregular metal powder can be achieved, thereby improving the quality of additive manufacturing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a structural diagram of a system for processing irregular metal powders provided in an embodiment of the present application;

FIG2 is a schematic diagram of a processing device in a processing system for irregular metal powders provided in an embodiment of the present application;

FIG3 is a partial enlarged view of a processing device provided in an embodiment of the present application;

FIG4 is a flow chart of a method for processing irregular metal powder provided in an embodiment of the present application;

FIG5a is a schematic diagram of contact and adhesion between two metal powders provided in an embodiment of the present application;

FIG5 b is a schematic diagram of partial embedding and bonding of two metal powders provided in an embodiment of the present application;

FIG5c is a schematic diagram of a complete embedding and bonding of two metal powders provided in an embodiment of the present application;

FIG6a is a schematic diagram of H13 steel powder before treatment provided in an embodiment of the present application;

FIG6 b is a schematic diagram of H13 steel powder after processing provided in an embodiment of the present application.

Figure numerals: 100-control device, 200-processing device, 1-loading bin, 2-first butterfly valve, 3-second butterfly valve, 4-flow meter, 5-first air inlet pipe, 6-spheroidizing chamber, 7-heat source structure, 8-thermocouple, 9-pressure gauge, 10-second air inlet pipe, 11-ultrasonic device, 12-third butterfly valve, 13-receiving bin, 14-first valve, 15-second valve, 16-vacuum system.

DETAILED DESCRIPTION

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

In the following, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, unless otherwise specified, "plurality" means two or more.

Additionally, the use of “based on” or “according to” is meant to be open and inclusive, in that a process, step, calculation, or other action “based on” or “according to” one or more conditions or values may, in practice, be based on additional conditions or beyond values.

The main preparation methods for spherical metal powders for additive manufacturing are gas atomization and plasma rotating electrode atomization. The differences in atomization mechanism and equipment structure determine the differences in powder properties.

The gas atomization method uses high-speed atomizing gas to impact and break the high-temperature molten liquid flow into small-sized metal droplets, and then the droplets are rapidly cooled and solidified into spherical particles in the atomization chamber. Due to the closed structure of the atomization chamber, a recirculation zone will be generated near the side wall. The small-sized particles swirling up in the recirculation zone will collide with the large-sized particle droplets that have not been completely solidified in the upstream atomization gas flow to form satellite powder. Therefore, metal powders prepared by the gas atomization method often contain a large amount of satellite powder.

In the plasma rotating electrode atomization powder making process, molten metal droplets are thrown out from the edge of the electrode rod. Due to the different speeds and angles of different droplets being thrown out, they have different flight trajectories in the atomization chamber, which will cause mutual collision and adhesion. At the same time, since the atomization chamber is filled with inert gas, gas is continuously introduced into the atomization chamber during the production process, forming a circulating airflow in the atomization chamber. The lighter particles are suspended and rolled in the cavity by the impact of the airflow. When colliding with the particles that are not completely solidified, they will stick together to form satellite powder. When the plasma rotating electrode method is used to prepare metals or alloys with low thermal conductivity or low surface tension, the atomized particles cool slowly, and the generation of satellite powder and adhesion powder will increase. The presence of satellite powder will reduce the bulk density, sphericity and fluidity of metal powder, and have an adverse effect on the metal additive manufacturing process.

In general, although the gas atomization method has a relatively low production cost and a high fine powder yield, a large amount of satellite powder is produced in the prepared metal powder. The metal powder produced by the plasma rotating electrode atomization method is generally of high powder quality and a small amount of satellite powder. However, when preparing some metals or alloys with low surface tension and low thermal conductivity (such as titanium alloy), a large amount of irregular powder will also be formed, such as non-spherical powder, satellite powder and adhesion powder.

However, the current additive manufacturing technology has high requirements on the fluidity of powder, whether it is powder spreading or powder feeding. This irregular shape will directly reduce the fluidity of powder and easily cause equipment blockage. At the same time, it is difficult to spread a flat and uniform powder layer, which reduces the dimensional accuracy and surface forming quality of printed parts.

In response to the above problems, an embodiment of the present application provides a system for processing irregular metal powders. As shown in FIG1 , the system includes a control device 100 and a processing device 200. As shown in FIG2 , the processing device 200 includes a spheroidizing chamber 6. The spheroidizing chamber 6 includes a heat source structure 7. The heat source structure 7 is used to form a heat source area. The metal powder flows through the heat source area so that the heat source area performs secondary spheroidization treatment on the metal powder flowing through.

The control device 100 is used to obtain the melting point of the metal powder and the critical pressure at which the metal powder volatilizes; determine the target pressure in the spheroidizing chamber 6 according to the critical pressure, determine the target temperature of the heat source area according to the melting point, and determine the target length range of the heat source area, wherein the target length range is the distance range of the metal powder flowing through the heat source area; control the heat source structure 7 to generate a heat source area with a target temperature and a target length range, and control the spheroidizing chamber 6 to be under the target pressure, and control the metal powder to be added to the spheroidizing chamber 6 and flow through the heat source area, so that the heat source area performs secondary spheroidization on the metal powder.

It should be noted that the metal powder targeted by the embodiments of the present application is an irregular powder formed in the process of preparing metal powder by atomization method.

Optionally, the control device 100 is specifically used to: determine the time required for heat to reach the center of the metal powder sphere based on the heat required for melting the two metal powders at the adhesion point, the thermal conductivity of the metal powder, the initial temperature of the metal powder and the melting point of the metal powder, as well as the preset radius of the metal powder and the surface area of the metal powder; determine the movement distance of the metal powder in the heat source area when melting the two adhering metal powders based on the required time and the preset gas flow rate; and determine the target length range of the heat source area based on the movement distance.

Optionally, the control device 100 is specifically used to determine the heat required for melting the adhesion between two metal powders according to the acquired specific heat capacity, density, volume, initial temperature and melting point of the metal powder.

Optionally, the top of the spheroidizing chamber 6 of the processing device 200 is connected to a loading bin 1, the bottom of the spheroidizing chamber 6 is connected to a receiving bin 13, and the heat source area is located between the loading bin 1 and the receiving bin 13; the metal powder is added from the loading bin 1, flows through the heat source area and falls into the receiving bin 13.

The spheroidizing chamber 6 further comprises an ultrasonic device 11, and the ultrasonic wave generated by the ultrasonic device 11 acts on the heat source area; the heat source structure 7 comprises a plasma torch device, a microwave heating device or an induction heating device.

The processing device 200 also includes a vacuum system 16; the control device is also used to control the vacuum system 16 to vacuum the loading bin 1, the spheroidizing chamber 6 and the receiving bin after the metal powder is added to the loading bin 1.

As shown in FIG3 , two first air inlet pipes 5 are provided on two sides of the upper bin 1, and the tail of the first air inlet pipe 5 forms an angle along the axial direction of the upper bin 1, and the angle range is 30-60°. Inert gas is introduced into the air inlet pipe; the first air inlet pipe 5 is used to disperse the metal powder entering the heat source area by using the airflow in the pipe. The inert gas can be: Ar gas, He gas or a mixture of the two.

The spheroidizing chamber 6 further includes a second air inlet pipe 10; the control device is further used to introduce inert gas into the spheroidizing chamber 6 from the second air inlet pipe 10 after the spheroidizing chamber 6 is vacuumed. The spheroidizing chamber 6 also includes a pressure detection device, which is used to detect the gas pressure in the spheroidizing chamber 6.

In general, the spheroidization device 200 is mainly composed of a loading bin 1, a spheroidization chamber 6, a receiving bin and a vacuum system 16. The spheroidization chamber 6 includes: a heat source structure 7, a thermocouple 8, an ultrasonic device 11, a first air intake pipe 5, a second air intake pipe 10, a first butterfly valve 2, a second butterfly valve 3, a third butterfly valve 12, a pressure gauge 9 and a flow meter 4. The vacuum system 16 is connected to a first valve 14 and a second valve 15.

Among them, a first air intake pipe 5 is arranged outside the upper bin 1, as shown in FIG3, after entering the first air intake pipe 5 and entering the spheroidizing chamber 6, it is divided into two symmetrical pipes along the radial direction of the upper bin 1, and the end of the first air intake pipe 5 is arranged to form a certain angle along the axial direction, and the angle variation range is 30-60 degrees, and the end of the first air intake pipe 5 faces the axial direction of the spheroidizing chamber 6. The first air intake pipe 5 is used to fully disperse the falling powder before entering the heat source area, so that it is evenly heated, and at the same time, the falling speed of the powder is accelerated. A flow meter 4 is installed on the first air intake pipe 5 to adjust the size of the intake volume, and the intake flow rate can be continuously adjusted within the range of 0-50m/s. The heat source structure 7 for heating can be a plasma torch, microwave or induction heating, etc. According to the type and particle size of the processed powder, the temperature of the heat source area can be adjusted between 0-5000 degrees Celsius.

Thermocouples 8 are installed at the center and edge of the heat source area to measure the temperature changes at the center and edge of the heat source, so as to adjust the temperature of the heat source. A second air inlet pipe 10 is also connected to the spheroidizing chamber 6, which is used to fill the spheroidizing chamber 6 with inert protective gas after evacuating the spheroidizing chamber 6. A pressure gauge 9 is installed on the spheroidizing chamber 6 to monitor the gas pressure in the spheroidizing chamber 6. Depending on the type of powder to be processed, the gas pressure in the spheroidizing chamber 6 can be controlled within the range of 0-0.01MPa. By forming a certain gas pressure in the spheroidizing chamber 6, the volatilization of elements in the alloy during the secondary melting process can be effectively reduced to ensure that the composition of the re-spheroidized powder does not change. An ultrasonic device is symmetrically installed on the inner wall of the spheroidizing chamber 6. The ultrasonic wave generated by the ultrasonic device acts on the heat source area to accelerate the separation of the melted satellite powder and the adhesion powder particles from each other.

The method for using the processing device 200 may be as follows: Step 1, open the first butterfly valve 2, close the second butterfly valve 3, add the powder to be processed into the upper bin 1, and then close the first butterfly valve 2; Step 2, open the third butterfly valve 12 and the first valve 14 and the second valve 15, open the vacuum system 16, evacuate the upper bin 1, the spheroidizing chamber 6 and the receiving bin 13, and when the vacuum degree reaches 10 ^-3 Pa, stop vacuuming, close the first valve 14 and the second valve 15, open the valve on the second air inlet pipe 10 to fill the spheroidizing chamber 6 with inert gas; Step 3, open the heat source structure 7, open the valve of the first air inlet pipe 5 in the heat source area, open the second butterfly valve 3, let the powder fall and be fully dispersed under the action of the gas, and the powder will be partially melted after falling to the heat source area, and the separation of the satellite powder and the adhesion powder after the "neck" melting will be accelerated under the action of the ultrasonic device 11, and then spheroidized again under the action of surface tension, and the powder after the secondary spheroidization treatment will enter the receiving bin 13; Step 4, after the powder in the upper bin 1 is processed, close the second butterfly valve 3, open the first butterfly valve 2, add the powder to be processed again, close the first butterfly valve 2, open the second valve 15 and the vacuum system 16 to vacuum the upper bin 1, close the second valve 15 and the vacuum system 16 after the vacuum degree reaches the requirement, and open the second butterfly valve 3 to start the powder processing. Repeat the above step 4 until all the metal powders are processed.

Based on the above-mentioned irregular metal powder processing system and processing device provided in the embodiment of the present application, the embodiment of the present application also provides a method for processing irregular metal powder, as shown in FIG4 , the method specifically comprises the following steps:

Step 401: Obtain the melting point of metal powder and the critical pressure of volatilization of the metal powder.

Step 402: determining a target pressure in the spheroidizing chamber according to the critical pressure, determining a target temperature of the heat source region according to the melting point, and determining a target length range of the heat source region, wherein the target length range is a distance range of the metal powder flowing through the heat source region.

The target temperature of the heat source region can be set to be 50-100° C. higher than the melting point of the metal powder.

In addition, since the metal powder will undergo secondary melting under high temperature and vacuum conditions, the problem of volatilization of alloy elements in the metal powder will be faced during the processing of the metal powder.

The relationship between the volatilization rate of metals and alloys and temperature and pressure has the following characteristics: 1) When the pressure is greater than the critical pressure When the evaporation rate As the pressure increases, it decreases. 2) When the pressure is equal to the critical pressure When the evaporation rate Reach the maximum value; 3) When the pressure is less than the critical pressure When the evaporation rate It is a fixed value and is not affected by pressure changes. 4) Critical pressure Saturated vapor pressure of metal related, It only depends on the temperature, so when the temperature is constant Is a fixed value.

Therefore, when processing metal powder, in order to avoid the volatilization of metal elements during the secondary spheroidization of metal powder, the pressure in the spheroidization chamber can be increased so that the pressure in the spheroidization chamber is greater than the critical pressure for the volatilization of metal powder.

Step 403, controlling the heat source structure to generate a heat source region with a target temperature and a target length range, and controlling the spheroidizing chamber to be at a target pressure, controlling the metal powder to be added into the spheroidizing chamber and flow through the heat source region, so that the heat source region performs secondary spheroidization on the metal powder.

Optionally, the process of determining the target length range of the heat source region in step 402 may be:

The time required for the heat to reach the center of the metal powder sphere is determined based on the heat required for melting the two metal powders at the adhesion point, the thermal conductivity of the metal powder, the initial temperature of the metal powder and the melting point of the metal powder, as well as the preset radius of the metal powder and the surface area of the metal powder. The movement distance of the metal powder in the heat source area when melting the two adhering metal powders is determined based on the required time and the preset gas flow rate. The target length range of the heat source area is determined based on the movement distance.

The process of determining the heat required for melting the adhesion between two metal powders may be as follows: determining the heat required for melting the adhesion between two metal powders according to the obtained specific heat capacity, density, volume, initial temperature and melting point of the metal powders.

For example, assume that two metal powder particles that are attached to each other are spheres, and the heat transfer is uniform along the radius of the sphere. The radius of the larger particle is R, the radius of the smaller particle is r, and the mass of the sphere is , the volume of the sphere .

Taking TC4 titanium alloy as an example, the specific heat capacity of TC4 is 0.612 J/g·℃, the melting point is 1670℃, the density is 4.51 g/cm ³ , and the thermal conductivity is 7.955 w/(m·k). The adhesion morphology of two adhered metal powders can be the following three situations:

1. When large-particle metal powder (referred to as large balls) and small-particle metal powder (small balls) are just in contact and adhered (as shown in Figure 5a), the diameter of the large ball is 150μm and the diameter of the small ball is 15μm. In this case, it is only necessary to melt the surface of the small ball to separate the adhered particles. Therefore, the heat source temperature can be set higher than the melting point of the metal powder.

Among them, the heat required for melting the pellet is:

According to the heat flux formula:

In the formula is the specific heat capacity of the metal powder, is the density of the metal powder, is the heat flux density, is the heat conduction cross-sectional area, T is the heat conduction time, is the thermal conductivity, is the heat transfer length, which is the radius of the ball, is the initial temperature of the metal powder, is the temperature of the metal powder after absorbing heat. The time T required for the heat to reach the center of the ball can be calculated.

T

2. When the small ball is partially embedded in the big ball (as shown in Figure 5b), the radius of the big ball is R, the radius of the small ball is r, and the distance from the center of the big ball to the interface of the adhesion is L. At this time, the adhered particles need to be separated. The heat absorbed by the melting of the adhesion is:

3. When two larger metal particles are bonded together, such as half of a 150μm metal particle embedded in another particle (as shown in Figure 5c), the heat required to melt the bonded part is for:

Since the time that the metal powder passes through the range of the heat source is very short, the heat transferred by the powder spherical surface is the melting absorption heat. According to Newton's cooling law, the heat flux of convective heat transfer between the fluid and the solid wall is proportional to their temperature difference, that is:

Where: is the heat flux, unit ; , are the temperatures of the solid surface and the fluid, respectively, in units ; is the heat transfer area, unit ; is the area per unit time Heat transfer heat, unit ; is the surface convection heat transfer coefficient, in units .

The heat conduction relationship of the sphere can be obtained through the law of heat conduction, and the expression is:

in, is the heat transfer rate, is the thermal conductivity, is the heat transfer area, Represents the temperature difference, Represents the heat transfer distance.

For a sphere, the heat transfer area is the surface area of the sphere and can be expressed as: ,in is the radius of the sphere. Therefore, the heat conduction relationship of the sphere can be expressed as:

In the process of heat conduction in a sphere, the heat flux density represents the heat conduction rate per unit area and can be expressed as:

In summary, it can be expressed as ,but .

That is, the temperature difference from the surface of the sphere to the adhesion interface is 1.067K, which is very small.

Calculate the time T required for the heat to reach the center of the sphere:

T

Calculated based on the maximum gas flow rate of 50m/s, the distance the metal powder moves during the time it takes for the heat to reach the center of the sphere is 0.032m.

For the above three situations, it can be known that the adhesion situation as shown in Figure 5c is the maximum adhesion of the two largest metal powders. It takes the longest melting time to melt the adhesion situation as shown in Figure 5c, and the time for the metal powder to move in the heat source area is also the longest. Therefore, in order to ensure that the adhered metal powder is completely melted, the length of the heat source area needs to be greater than the distance of the metal powder movement calculated by melting the adhesion situation in Figure 5c. According to the above calculation, it needs to be greater than 0.032m.

Optionally, the spheroidization chamber further comprises an ultrasonic device, and the ultrasonic waves generated by the ultrasonic device act on the heat source area; the heat source structure comprises a plasma torch device, a microwave heating device or an induction heating device.

Optionally, the top of the spheroidizing chamber of the processing device is connected to a loading bin, the bottom of the spheroidizing chamber is connected to a receiving bin, and the heat source area is located between the loading bin and the receiving bin; the metal powder is added from the loading bin, flows through the heat source area and falls into the receiving bin.

Optionally, the processing device further includes a vacuum system, and the method further includes:

After the metal powder is added into the feeding bin, the control device controls the vacuum system to perform vacuum treatment on the feeding bin, the spheroidizing chamber and the receiving bin.

Optionally, two first air inlet pipes are provided on two sides of the loading bin, and the tail of the first air inlet pipe forms an angle along the axial direction of the loading bin, and the angle range is 30~60°, and inert gas is introduced into the air inlet pipe; the first air inlet pipe utilizes the airflow in the pipe to disperse the metal powder entering the heat source area.

Optionally, the spheroidizing chamber further includes a second air inlet pipe, and the method further includes: after the control device evacuates the spheroidizing chamber, an inert gas is introduced into the spheroidizing chamber from the second air inlet pipe.

Optionally, the spheroidizing chamber further includes a pressure detection device, and the pressure detection device is used to detect the gas pressure in the spheroidizing chamber.

In addition, this application also provides some specific embodiments.

Embodiment 1: In this embodiment, TC4 alloy powder prepared by gas atomization method is selected, and the powder particle size is less than 150μm. The powder is placed in the upper bin, the butterfly valve of the upper feeding port is closed, the butterfly valve of the receiving bin and the vacuum system are opened, and the upper bin, the spheroidizing chamber and the receiving bin are evacuated (the vacuum degree is ^10-3Pa ), and the inert gas charging valve is opened, and the gas pressure in the spheroidizing chamber is controlled at 10Pa (it is found that the critical pressure of the low melting point element Al at 1700℃ is about 4.67Pa), and the heat source is turned on to control the temperature at 1722-1772℃, and then the lower butterfly valve of the upper bin and the gas valve in the unloading channel are opened, and the gas flow rate is 10m/s. At the same time, the ultrasonic system in the spheroidizing chamber is turned on, and the satellite powder is quickly melted by the heat source. At the same time, the sticking particles are separated and re-spheroidized under the action of ultrasound, and the powder after re-spheroidization falls into the receiving bin. After testing and analyzing the treated powder and comparing it with the original powder, the composition of the treated powder is basically consistent with the original powder, there is no volatilization of alloy elements, the content of satellite powder in the treated powder is reduced by 90% compared with the original powder, and the powder quality is significantly improved.

Example 2: In this example, H13 steel powder prepared by plasma rotating electrode method is selected, and the powder particle size is 150-200μm. The powder is placed in the upper bin, the upper butterfly valve is closed, the receiving bin butterfly valve and the vacuum system are opened, and the upper bin, spheroidizing chamber and receiving bin are evacuated (vacuum degree to ^10-3Pa ), and the inert gas charging valve is opened, and the gas pressure in the spheroidizing chamber is controlled at 5Pa, and the heat source is turned on to control the temperature at 1470-1520℃, and then the lower butterfly valve of the upper bin and the gas valve in the unloading channel are opened, and the gas flow rate is 8m/s. At the same time, the ultrasonic system in the spheroidizing chamber is turned on, and the satellite powder is quickly melted under the action of the heat source, and the adhered particles are separated and re-spheroidized under the action of ultrasound, and the powder after re-spheroidization falls into the receiving bin. Comparing the treated powder with the original powder, it is found that the content of satellite powder and adhered "beaded" powder in the treated H13 steel powder is reduced by more than 95% compared with the original powder. Among them, Figure 6a shows the H13 steel powder before treatment, and Figure 6b shows the H13 steel powder after treatment. It can be seen that the content of satellite powder and adhered "beaded" powder in the H13 steel powder after treatment is significantly reduced compared with the original powder.

The method for treating irregular metal powder provided in the embodiment of the present application can treat irregular powders such as satellite powder formed by gas atomization method and plasma rotating electrode method. When the irregular powder to be treated falls from the upper silo, the powder will be fully dispersed under the action of the symmetrical pipeline airflow before entering the heat source action area, so that the adhesion of the satellite powder can be quickly heated and melted. At the same time, an ultrasonic device is symmetrically installed on the inner wall of the spheroidization chamber, and the partially melted adhesion powder particles are accelerated to separate from each other under the action of ultrasound, and then cooled under the action of surface tension to form a regular spherical powder. During the treatment process, some dispersed ellipsoidal or irregular shaped particles will also be melted and then formed into spherical powder, thereby improving the quality of the powder. The heat source used for heating can be a plasma torch, microwave or induction heating, etc., and the temperature of the heat source can be adjusted between 0-5000 degrees Celsius according to the type and particle size of the powder to be treated. The spheroidization chamber is filled with an inert protective gas after vacuuming, so that the powder will not be oxidized during the re-spheroidization treatment. In order to avoid the volatilization of alloy elements during the high-temperature melting of metal powders, the pressure of the inert gas in the spheroidizing chamber can be adjusted and controlled according to the type of powder being processed, so as to reduce the volatilization of elements in the alloy during the secondary melting process and ensure that the composition of the re-spheroidized powder does not change.

In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using a software program, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer execution instruction is loaded and executed on the computer, the process or function according to the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instruction can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instruction can be transmitted from a website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (digital subscriber line, DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium can be any available medium that can be accessed by the computer or a data storage device such as a server, data center, etc. that contains one or more servers that can be integrated with the medium. The available medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a DVD), or a semiconductor medium (eg, a solid state disk (SSD)).

The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims (10)

1. A method for processing irregular metal powder, characterized in that the method is applied to a control device in a system for processing irregular metal powder, the system further comprising a processing device, the processing device comprising: a spheroidizing chamber, the spheroidizing chamber comprising a heat source structure, the heat source structure being used to form a heat source area, the metal powder flows through the heat source area, so that the heat source area performs secondary spheroidizing treatment on the metal powder, the method comprising: Obtaining the melting point of the metal powder and the critical pressure at which the metal powder volatilizes; Determining a target pressure in the spheroidizing chamber according to the critical pressure, determining a target temperature of the heat source region according to the melting point, and determining a target length range of the heat source region, wherein the target length range is a distance range of the metal powder flowing through the heat source region; The heat source structure is controlled to generate a heat source region with a target temperature and a target length range, and when the spheroidizing chamber is controlled to be at a target pressure, the metal powder is controlled to be added into the spheroidizing chamber and flow through the heat source region, so that the heat source region performs a secondary spheroidizing treatment on the metal powder. 2. The method according to claim 1, characterized in that the determining of the target length range of the heat source area comprises: The time required for the heat to reach the center of the metal powder sphere is determined based on the heat required for melting the adhesion between the two metal powders, the thermal conductivity of the metal powder, the initial temperature of the metal powder, the melting point of the metal powder, the preset radius of the metal powder, and the surface area of the metal powder; Determining the movement distance of the metal powders in the heat source region when melting two adhering metal powders according to the required time and the preset gas flow rate; The target length range of the heat source area is determined according to the movement distance. 3. The method according to claim 2, characterized in that obtaining the heat required for melting the adhesion between the two metal powders comprises: The heat required to melt the adhesion between two metal powders is determined based on the specific heat capacity, density, volume, initial temperature and melting point of the metal powders. 4. A device for processing irregular metal powders, characterized in that the device is located in a system for processing irregular metal powders, and the system further comprises a control device; The processing device comprises: a spheroidizing chamber, wherein the spheroidizing chamber comprises a heat source structure, wherein the heat source structure is used to form a heat source region, and the metal powder flows through the heat source region so that the heat source region performs a secondary spheroidizing treatment on the metal powder; The control device is used to obtain the melting point of the metal powder and the critical pressure at which the metal powder volatilizes; determine the target pressure in the spheroidizing chamber according to the critical pressure, determine the target temperature of the heat source area according to the melting point, and determine the target length range of the heat source area, wherein the target length range is the distance range of the metal powder flowing through the heat source area; control the heat source structure to generate a heat source area with a target temperature and a target length range, and control the metal powder to be added into the spheroidizing chamber and flow through the heat source area when the spheroidizing chamber is under the target pressure, so that the heat source area performs secondary spheroidization on the metal powder. 5. The processing device according to claim 4, characterized in that the spheroidizing chamber further comprises an ultrasonic device, and the ultrasonic wave generated by the ultrasonic device acts on the heat source area; The heat source structure includes a plasma torch device, a microwave heating device or an induction heating device. 6. The processing device according to claim 4, characterized in that the top of the spheroidizing chamber of the processing device is connected to a loading bin, the bottom of the spheroidizing chamber is connected to a receiving bin, and the heat source area is located between the loading bin and the receiving bin; The metal powder is added from the loading bin, flows through the heat source area and falls into the receiving bin. 7. The processing device according to claim 6, characterized in that the processing device also includes a vacuum system; The control device is also used to control the vacuum system to perform vacuum treatment on the loading bin, the spheroidizing chamber and the receiving bin after the metal powder is added into the loading bin. 8. The processing device according to claim 6, characterized in that two first air inlet pipes are arranged on two sides of the upper material bin, the tail of the first air inlet pipe forms an angle along the axial direction of the upper material bin, the angle range is 30-60°, and inert gas is introduced into the air inlet pipe; The first air inlet pipe is used to utilize the airflow in the pipe to disperse the metal powder entering the heat source area. 9. The processing device according to claim 7, characterized in that the spheroidizing chamber further comprises a second air inlet pipe; The control device is also used to introduce inert gas into the spheroidizing chamber from the second air inlet pipe after the spheroidizing chamber is vacuumized. 10. The processing device according to claim 9, characterized in that the spheroidizing chamber further comprises a pressure detection device, and the pressure detection device is used to detect the gas pressure in the spheroidizing chamber.