CN111761070A - A powder feeding system for nano powder preparation process - Google Patents

Abstract

A powder feeding system of a nano powder preparation process comprises a storage bin, a spiral feeder, a powder feeder and a flexible pinch valve. The feed bin is provided with a material level meter, and a feeding screw rod in the spiral feeder is connected with a speed regulating motor through magnetic coupling. The diameter of the powder feeder is larger than the inner diameter of the powder feeding barrel, and a plurality of feeding through holes are arranged in the circumferential direction of the powder feeding disk. When the powder feeding plate rotates, the feeding through hole which is screwed out of the inner cavity of the powder feeding barrel is correspondingly communicated with the discharging hole and the air inlet hole. The flexible pinch valve comprises a rubber tube and two pairs of pinch rods, and each pair of pinch rods is connected with an electric push rod. When the electric push rod moves, the pair of clamping rods clamp the rubber tube. The discharge end of the rubber tube is provided with an air tap which is connected with a vacuumizing device and a working gas recharging device. The invention solves the problem that the sealing, transmission, conveying and the like of the micron-level powder raw material are difficult to solve in the powder feeding process, and can stably and accurately control the conveying amount of the powder raw material, so that the plasma flame flow is stable, and the required particle size of the nano powder is further achieved.

Description

A powder feeding system for nano powder preparation process

technical field

The invention relates to the field of nano-powder preparation devices, in particular to a powder feeding system of a nano-powder preparation process.

Background technique

Metal nanopowders have been used in materials, electronics, information, medicine, aerospace and other fields, and can be used in the preparation of new high-capacity magnetic materials, high-efficiency catalysts, magnetic fluids, wave-absorbing materials, and high-efficiency combustion accelerants. The methods for preparing metal nanopowder include sputtering method, microwave energy method, arc plasma method, electric explosion method, laser method, chemical method, etc. At present, the arc plasma method is often used.

In the process of preparing nano-powder by arc plasma method, the powder raw material needs to be heated in the plasma furnace through the powder feeding system. Feeding devices are used in all kinds of equipment, but in the field of nano-powder preparation technology, there are problems that do not exist in other fields:

1. Since the diameter of the powder raw material is in the micron level, the conventional feeding structures such as sealing, transmission, and transportation commonly used in other fields are no longer effective;

2. The uniformity of powder raw material transportation will affect the stability of the plasma flame and the particle size of the prepared nano-powder;

3. In the process of powder raw material transportation, the purity of the powder raw material transportation gas should be ensured, and other gases should not be mixed to ensure that the powder raw material does not undergo oxidation and nitridation reactions in the high-temperature plasma flame flow;

4. Because the whole process of powder feeding is sealed, it is difficult for the operator to grasp the powder feeding state and the problems that occur, resulting in unstable feeding of the plasma furnace, or even material failure;

5. Since a large amount of powder raw materials cannot be stored in the powder feeder, frequent addition of powder raw materials requires opening the powder feeder, which will cause the working gas in the powder feeder to flow out and allow outside air to enter, thereby affecting the plasma furnace. Operation and the quality of the prepared nano-powders, so how to achieve uninterrupted feeding of powder raw materials is also a difficult problem.

SUMMARY OF THE INVENTION

In order to overcome the deficiencies in the background technology, the present invention discloses a powder feeding system for a nano powder preparation process, which adopts the following technical solutions:

A powder feeding system for a nano powder preparation process, comprising:

The silo is connected with a vacuuming device and a working gas refilling device; a material level gauge is arranged on the silo;

The screw feeder is used to transport the powder material in the silo to the powder feeder, including a feeding pipe and a feeding screw arranged in the feeding pipe; the two ends of the feeding pipe are closed, and the feeding port and the discharging port are respectively It is arranged on the pipe wall near the two ends of the feeding pipe; the two ends of the feeding screw are respectively connected with the two closed ends of the feeding pipe in rotation, and one end of the feeding screw is non-contactingly connected with the speed regulating motor through the first magnetic coupling transmission wheel ;

The powder feeder includes a vertically arranged powder feeding bucket. The bottom plate of the powder feeding bucket is provided with a discharge hole, an air inlet hole and a rotating shaft hole. The axis of the rotating shaft hole is parallel to the axis of the powder feeding bucket and eccentrically arranged. A rotating shaft is connected with the inner rotation; one end of the rotating shaft facing the inside of the powder feeding bucket is connected with a powder feeding tray, and one end facing the outside of the powder feeding bucket is connected with a servo motor; between the upper surface of the powder feeding tray and the inner wall of the powder feeding bucket is arranged There is a powder scraping oil seal, and a sealing ring is arranged between the lower surface of the powder feeding tray and the bottom plate of the powder feeding barrel; the diameter of the powder feeding tray is larger than the inner diameter of the powder feeding barrel, and a plurality of powder feeding trays are arranged in the circumferential direction. Feeding through hole; when the powder feeding tray rotates, the feeding through hole that is screwed out of the inner cavity of the powder feeding barrel is connected with the discharge hole and the air intake hole correspondingly;

The flexible pinch valve includes a vertically arranged rubber tube. Two pairs of clamping rods are arranged on both sides of the rubber tube for clamping or loosening the rubber tube. The two pairs of clamping rods are arranged up and down; Rod connection is used to clamp the rubber tube; there is a gas nozzle at the discharge end of the rubber tube, and the gas nozzle is connected with a vacuuming device and a working gas refilling device;

Electronic scale, used to weigh the powder raw materials in the powder feeder;

The discharge port of the silo is connected with the feed port of the screw feeder through a flexible pinch valve, and the discharge port of the screw feeder is connected with the feed end of the powder feeder through a flexible bellows;

Control device, connected with silo, screw feeder, powder feeder, flexible pinch valve and electronic scale.

To further improve the technical scheme, the silo is provided with a material level observation window, and a camera for observing the material level through the material level observation window; the lower part of the silo is provided with an arch breaking air nozzle for preventing the powder raw material from arching, The arch-breaking gas nozzle is connected with the working gas.

To further improve the technical solution, the first magnetic coupling transmission wheel includes a first driving wheel and a first driven wheel, and magnetic coupling magnets are respectively arranged in the first driving wheel and the first driven wheel; The machine is connected with the speed regulating motor, and the first driven wheel is connected with the feeding screw.

To further improve the technical scheme, the two ends of the feeding screw are rotatably connected to the two closed ends of the feeding tube through the first bushing; the material of the first bushing is nylon or tetrafluoroethylene; The powder raw material enters the first high-pressure air passage of the first shaft sleeve, and the high-pressure working gas is introduced into the first high-pressure air passage.

The technical solution is further improved, and the end of the rotating shaft facing the powder feeding barrel is also connected with an axial stirring shaft, and is also connected with a plurality of radial stirring rods.

To further improve the technical scheme, a vertically arranged guide column is connected to the inner cavity wall of the powder feeding bucket, and a vibrating hammer is slidably connected to the guide column; The wedge-shaped surface of the vibrating hammer is in sliding contact, so that the vibrating hammer moves up and down and strikes the powder feeding tray.

The technical scheme is further improved. The bottom plate of the powder feeding bucket is provided with a second high-pressure air passage to prevent powder raw materials from entering the shaft hole, and a high-pressure working gas is introduced into the second high-pressure air passage.

The technical solution is further improved, a second shaft sleeve made of nylon or tetrafluoroethylene is arranged between the shaft hole and the shaft, and a ventilation hole is arranged on the second shaft sleeve, and the ventilation hole is communicated with the second high-pressure air passage.

To further improve the technical scheme, the rotating shaft and the servo motor are connected in non-contact through a second magnetic coupling transmission wheel; the second magnetic coupling transmission wheel includes a second driving wheel and a second driven wheel, and the second driving wheel and the second driving wheel are connected. Magnetically coupled magnets are respectively arranged in the second driven wheel; the second driving wheel is connected with the servo motor through a reducer, and the second driven wheel is connected with the rotating shaft; a sealing end cover is arranged between the second driving wheel and the second driven wheel , the sealing end cover is sealingly connected with the lower end face of the bottom plate of the powder feeding barrel.

To further improve the technical scheme, a glass viewing window cover is sealed and connected to the upper end of the powder feeding barrel, a feeding port is arranged on the glass viewing window cover, and the flexible bellows is communicated with the feeding port on the glass viewing window cover; There is a heating pipe in the barrel wall for drying powder raw materials.

Due to adopting the above-mentioned technical scheme, compared with the background technology, the present invention has the following beneficial effects:

The invention solves the difficult problems of sealing, transmission and transportation of micron-level powder raw materials in the powder feeding process through the positive pressure inflatable sealing structure, the magnetic coupling transmission structure and the unique quantitative conveying structure, and can be stably and accurately It can control the conveying amount of powder raw materials, stabilize the plasma flame flow, and then achieve the required nano powder particle size.

In the process of conveying powder raw materials, the invention purifies the purity of the conveying gas of the powder raw materials, and ensures that the powder raw materials do not undergo oxidation and nitridation reactions in the high-temperature plasma flame flow. The invention can also dry the powder raw material, and prevent the powder raw material from arching through the stirring mechanism and the rapping mechanism.

The control device of the present invention can automatically control the whole process of powder feeding, so as to prevent the plasma furnace from causing problems such as unstable feeding or even breaking of feeding. The operator can also grasp the working condition of the powder feeding system at any time.

Description of drawings

Figure 1 is a schematic diagram of the structure of the silo.

Figure 2 is a schematic diagram of the structure of the screw feeder.

Figure 3 is a schematic diagram of the structure of the powder feeder.

Figure 4 is a schematic view of the structure of the vibrating hammer.

FIG. 5 is a schematic structural diagram of a flexible pinch valve.

FIG. 6 is a schematic structural diagram of the present invention in Embodiment 1. FIG.

FIG. 7 is a schematic structural diagram of the powder feeder in Embodiment 2. FIG.

FIG. 8 is a schematic structural diagram of the present invention in Embodiment 2. FIG.

FIG. 9 is a schematic structural diagram of the powder feeder in Example 3. FIG.

In the picture: 1, silo; 1.1, material level meter; 1.2, material level observation window; 1.3, camera; 1.4, broken arch air nozzle; 1.5, air extraction nozzle; 2, screw feeder; 2.1, feeding pipe; 2.11 , the first high pressure air passage; 2.2, the feeding screw; 2.3, the speed regulating motor; 2.4, the first magnetic coupling transmission wheel; 2.5, the first shaft sleeve; 3, the powder feeder; 3.1, the powder feeding barrel; 3.11, the discharge hole; 3.12, air inlet; 3.13, second high pressure air passage; 3.14, glass window cover; 3.15, heating pipe; 3.2, rotating shaft; 3.3, powder feeding tray; 3.31, feeding through hole; 3.4, servo motor; 3.5, Stirring shaft; 3.6, stirring rod; 3.7, guide column; 3.8, vibrating hammer; 3.81, wedge surface; 3.9, second shaft sleeve; 4, flexible pinch valve; 4.1, rubber tube; 4.2, pinch rod; 4.3, electric Push rod; 4.4, air nozzle; 5, electronic scale; 6, flexible bellows; 7, pressure reducing valve; 8, spring plate; 9, wedge block; 10, vibration block.

Detailed ways

Preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principle of the present invention, and are not intended to limit the protection scope of the present invention.

Example 1:

A powder feeding system for a nano powder preparation process, as shown in Figure 6, includes a silo 1, a screw feeder 2, a powder feeder 3, a flexible pinch valve 4, an electronic scale 5, and a control device. The discharge port of the silo 1 is connected to the feed port of the screw feeder 2 through the flexible pinch valve 4, and the discharge port of the screw feeder 2 is connected to the feed end of the powder feeder 3 through the flexible bellows 6. The powder raw material in the silo 1 is quantitatively fed into the powder feeder 3 through the screw feeder 2 to ensure that the powder raw material in the powder feeder 3 is continuously fed, so that the powder feeder 3 outputs a constant amount of powder raw material to the downstream equipment. The following is a detailed description:

As shown in FIG. 1 , the silo 1 is arranged vertically, and a vacuuming device and a working gas refilling device are connected to the silo 1 . The upper part of the silo 1 is provided with a suction nozzle 1.5, and the suction nozzle 1.5 is connected with a vacuum device (not shown in the figure) for extracting the impurity gas in the silo 1. The lower part of the silo 1 is provided with an arch breaking air nozzle 1.4, and the arch breaking air nozzle 1.4 is connected with the working gas refilling device. The function of the arch breaking air nozzle 1.4 is to refill the working gas into the silo 1; Arching, resulting in the problem that the powder raw material cannot be discharged smoothly. The working gas is the protective gas heated by the powder raw material in the plasma furnace, and is also the conveying gas of the powder raw material in the powder feeding system. In this embodiment, the working gas is high-purity argon.

In order to ensure continuous feeding, the silo 1 is provided with a material level meter 1.1 for monitoring the material level of powder raw materials. The material level meter 1.1 is a resistance-rotating material level meter, which can transmit the material level information of powder raw materials by electrical signals. In order to facilitate manual monitoring by the operator and further improve the technical solution, a material level observation window 1.2 is provided on the silo 1, and a camera 1.3 for observing the material level through the material level observation window 1.2 is also provided. The operator can visually see the material level of the silo 1 through the camera 1.3 in the control room.

The screw of the traditional screw feeder is directly connected with the motor, and the screw shaft and the conveying trough are connected by bearings and sealed with an oil seal. However, the diameter of the powder material is in the micrometer level, and the powder material of this level is pervasive. The conventional oil seal cannot effectively seal the powder material. The powder material will enter the bearing and even the motor, causing wear to the bearing and the motor. For this reason It is necessary to carry out a new structural design for the screw feeder.

As shown in Figure 2, the screw feeder 2 includes a feeding pipe 2.1 and a feeding screw 2.2. The feeding pipe 2.1 is arranged horizontally, and a feeding screw 2.2 is installed in the feeding pipe 2.1. The middle part of the feeding screw 2.2 has a helical conveying blade, and the helical conveying blade and the inner circular surface of the feeding pipe 2.1 form a conveying cavity for conveying powder raw materials. The two ends of the feeding pipe 2.1 are closed, and the feeding port and the discharging port are respectively arranged on the pipe wall near the two ends of the feeding pipe 2.1. The two ends of the feeding screw 2.2 are respectively connected with the two closed ends of the feeding pipe 2.1 through the shaft sleeve, and one end of the feeding screw 2.2 is connected to the speed regulating motor 2.3 non-contact through the first magnetic coupling transmission wheel 2.4. The first magnetic coupling transmission wheel 2.4 includes a first driving wheel and a first driven wheel, and magnetic coupling magnets are respectively arranged in the first driving wheel and the first driven wheel. The first driving wheel is connected with the speed regulating motor 2.3 through the reducer, and the first driven wheel is connected with the feeding screw 2.2. A sealing cover is arranged between the first driving wheel and the first driven wheel, and the sealing cover is in sealing connection with the end face of the feeding pipe 2.1. It is easy to see from the figure that the feeding pipe 2.1 is in a fully sealed state except for the feeding port and the discharging port. When the speed regulating motor 2.3 rotates, under the action of the coupled magnetic force, the first driving wheel drives the first driven wheel and the feeding screw 2.2 to rotate, thereby realizing the non-contact transmission between the speed regulating motor 2.3 and the feeding screw 2.2. The advantage of this non-contact transmission is that there is no need for rotational sealing of the rotating parts. As we all know, in mechanical seals, fixed seals are easy to achieve, and the most difficult to achieve is rotary seals. The wear of the rotating parts to the sealing parts is the main reason for the leakage, and the screw feeder 2 adopts non-contact transmission, avoiding the conventional rotary sealing structure, so as to ensure the complete sealing of the screw feeder 2 .

In order to solve the problem of bearing wear, the technical solution is further improved, and a first bushing 2.5 made of nylon is arranged between the feeding pipe 2.1 and the feeding screw 2.2. The first bushing 2.5 made of nylon has a smooth surface, low friction, high mechanical strength and self-lubrication, and does not require lubricating oil or grease, which is especially suitable for such occasions where the transmission torque is not large. A first high-pressure air passage 2.11 is provided on the feeding pipe 2.1, and a high-pressure working gas is introduced into the first high-pressure air passage 2.11. The pressure of the high-pressure working gas is greater than the pressure of the working gas in the feeding pipe 2.1, and the high-pressure working gas creates a local high-pressure environment at the first bushing 2.5, which can effectively prevent powder raw materials from entering the first bushing 2.5. Similarly, the shaft sleeve located on the other end of the feeding screw 2.2 can also be used in the same way to prevent the entry of powder raw materials. Because the high-pressure working gas is the same working gas, it will not pollute the internal gas environment. In addition, the leakage of the high-pressure working gas at the position 2.5 of the first shaft sleeve is limited, which will not cause large fluctuations to the internal working gas pressure. In order to control the conveying amount of the powder raw material, the control of the conveying amount of the powder raw material is realized by changing the speed of the speed regulating motor 2.3.

As shown in Figure 3, the powder feeder 3 includes a vertically arranged powder feeding bucket 3.1. In order to remove the moisture of the powder raw material in the powder feeding bucket 3.1 and prevent the powder raw material from being hardened due to moisture absorption, the technical solution is further improved. A heating pipe 3.15 for drying powder raw materials is arranged in the barrel wall of the powder feeding barrel 3.1. In order to facilitate the operator to observe the powder feeding state, a glass window cover 3.14 is sealed and connected to the upper end of the powder feeding bucket 3.1, and a camera is arranged above the glass window cover 3.14, and the operator can visually see the powder feeding bucket through the camera in the control room. 3.1 working conditions. A feeding port is provided on the glass viewing window cover 3.14, and the flexible bellows 6 communicates with the feeding port on the glass viewing window cover 3.14.

The bottom plate of the powder feeding bucket 3.1 is provided with a discharge hole 3.11, an air inlet hole 3.12 and a rotating shaft hole. The axis of the rotating shaft hole is parallel and eccentric to the axis of the powder feeding bucket 3.1, and a rotating shaft 3.2 is rotatably connected in the rotating shaft hole. One end of the rotating shaft 3.2 facing the inside of the powder feeding barrel 3.1 is connected with a powder feeding tray 3.3, and one end facing the outside of the powder feeding barrel 3.1 is connected with a servo motor 3.4. A plurality of feeding through holes 3.31 are arranged in the circumferential direction of the powder feeding tray 3.3. Under the action of gravity, the powder raw material enters the feeding through holes 3.31. A powder scraping oil seal is arranged between the upper surface of the powder feeding tray 3.3 and the inner wall of the powder feeding barrel 3.1 to scrape off the excess powder raw material outside the feeding through hole 3.31. A sealing ring is arranged between the lower surface of the powder feeding tray 3.3 and the bottom plate of the powder feeding bucket 3.1, which is used to block the powder raw material in the feeding through hole 3.31 and keep the filling amount of the powder raw material in the feeding through hole 3.31 constant. .

Since the diameter of the powder feeding tray 3.3 is larger than the inner diameter of the powder feeding barrel 3.1, when the powder feeding tray 3.3 rotates, the feeding through hole 3.31 of the inner cavity of the powder feeding barrel 3.1 is connected with the discharging hole 3.11 and the air inlet hole 3.12 correspondingly. The high-pressure working gas is fed into the air inlet hole 3.12, and the high-pressure working gas blows the powder raw material in the feeding through hole 3.31 into the discharging hole 3.11. Since the filling amount of the powder raw material in each feeding through hole 3.31 is constant, controlling the rotation speed of the servo motor 3.4 can precisely control the conveying amount of the powder raw material. The uniform delivery of powder raw materials can ensure the stability of the ion flame flow, and can achieve the particle size of the prepared nano-powder.

The diameter of the powder raw material is in the micron level, which is easy to cause arching due to accumulation. In order to prevent the powder raw material in the powder feeding barrel 3.1 from falling into the feeding through hole 3.31 effectively due to arching, and to further improve the technical solution, an axial stirring shaft 3.5 is also connected to the end of the rotating shaft 3.2 facing the powder feeding barrel 3.1 , and a plurality of radial stirring rods 3.6 are also connected. The stirring shaft 3.5 and the stirring rod 3.6 can agitate the powder raw materials in multiple dimensions to prevent the powder raw materials from arching.

In order to prevent the powder raw material from entering the shaft hole, wear the shaft 3.2, and further improve the technical solution, a sealing ring is provided between the lower surface of the powder feeding tray 3.3 and the bottom plate of the powder feeding bucket 3.1. On the bottom plate of the powder feeding bucket 3.1 A second high-pressure air passage 3.13 is provided to prevent the powder raw material from entering the shaft hole, and a high-pressure working gas is introduced into the second high-pressure air passage 3.13. The pressure of the high-pressure working gas is greater than the pressure of the working gas in the powder feeding barrel 3.1, and the high-pressure working gas forms a local high pressure at the shaft hole, which can effectively prevent powder raw materials from entering the shaft hole. The high-pressure working gas and the same working gas will not pollute the internal gas environment. In addition, the leakage of high-pressure working gas at the shaft hole is limited, which will not cause large fluctuations to the internal working gas pressure.

In order to keep the working gas pressure in the powder feeder 3 stable, a pressure reducing valve 7 and a pressure gauge are connected to the powder feeding barrel 3.1. When the pressure in the powder feeding barrel 3.1 is greater than the air pressure required by the process, the pressure reducing valve 7 is decompressed to keep the pressure of the working gas in the powder feeding barrel 3.1 stable.

As shown in Figure 4, in order to fill each feeding through hole 3.31 with powder raw materials, and to further improve the technical solution, a vertically arranged guide column 3.7 is connected to the inner cavity wall of the powder feeding barrel 3.1. The upper sliding connection is provided with a vibrating hammer 3.8. The vibrating hammer 3.8 is provided with a wedge-shaped surface 3.81. When the rotating shaft 3.2 rotates, the stirring rod 3.6 is in sliding contact with the wedge-shaped surface 3.81 of the vibrating hammer 3.8, so that the vibrating hammer 3.8 moves up and down and strikes the powder feeding tray 3.3. In this embodiment, six stirring rods 3.6 are arranged on the rotating shaft 3.2. Each time the rotating shaft 3.2 makes one revolution, the vibrating hammer 3.8 strikes the powder feeding tray 3.3 six times, and the vibration makes the powder raw material fill the feeding through hole 3.31.

Since the diameter of the powder raw material is in the micron level, the traditional plate valve and ball valve are easily stuck due to entering the powder raw material, so a specially designed flexible pinch valve 4 is required.

As shown in Figure 5, the flexible pinch valve 4 includes a vertically arranged rubber tube 4.1. Two pairs of clamping rods 4.2 for clamping or loosening the rubber tube 4.1 are provided on both sides of the rubber tube 4.1. The two pairs of clamping rods 4.2 are up and down. set up. Each pair of clamping rods 4.2 is connected with an electric push rod 4.3. When the flexible pinch valve 4 is closed, the two pairs of pinch rods 4.2 approach each other under the action of the electric push rod 4.3, clamp the rubber tube 4.1, and close the discharge port of the silo 1; when the flexible pinch valve 4 is opened, the two Under the action of the electric push rod 4.3, the clamping rod 4.2 moves away in the opposite direction, and the rubber tube 4.1 is loosened, so that the powder material in the silo 1 enters the screw feeder 2. By controlling the opening amount of the electric push rod 4.3, the flow of powder raw materials can be controlled. The reason why two pairs of clamping rods 4.2 are provided is because powder raw materials are retained in the tight rubber tube 4.1. The upper pair of clamping rods 4.2 cannot completely close the rubber tube 4.1, while the lower pair of clamping rods 4.2 does not retain powder due to the rubber tube 4.1. body material, so that the rubber tube 4.1 can be completely closed.

In order to ensure the purity of the powder raw material conveying gas, and other gases cannot be mixed, a gas nozzle 4.4 is provided at the discharge end of the rubber tube 4.1, and the gas nozzle 4.4 is connected with a vacuum device, and the vacuum device extracts the screw feeder 2, powder feeder The impurity gas in 3 is backfilled with the working gas.

As shown in FIG. 6 , the electronic scale 5 is arranged under the powder feeder 3 and is used for weighing the powder feeder 3 and the powder raw materials in the powder feeder 3 . In order to reduce the influence of the upstream screw feeder 2 on the weight, the discharge port of the screw feeder 2 is connected to the feed end of the powder feeder 3 through a flexible corrugated pipe 6 . The flexible bellows 6 does not transmit the force of the screw feeder 2 on the powder feeder 3, and the two ends of the flexible bellows 6 can be kept in sealed communication with the discharge port of the screw feeder 2 and the feed end of the powder feeder 3. .

The control device is connected with the silo 1, the screw feeder 2, the powder feeder 3, the flexible pinch valve 4 and the electronic scale 5 for automatic control. The control device includes a PLC controller, which can automatically control the whole process of powder feeding and reduce the labor of the operator.

working principle:

The material level meter 1.1 can transmit the material level information of the powder raw material to the PLC controller with an electrical signal, so as to prevent the plasma furnace from being cut off due to the lack of material in the silo 1. Before working, the flexible pinch valve 4 is closed. The PLC controller opens the vacuuming device on the silo 1 and the flexible pinch valve 4, evacuates the impurity gas in the silo 1, the screw feeder 2, and the powder feeder 3, and then fills the working gas through the backfilling device. This cycle is repeated several times to keep the working gas in the powder feeding system pure.

When working, the PLC controller properly opens the opening area of the rubber tube 4.1 through the electric push rod 4.3, so that the powder raw material in the silo 1 enters the powder feeder 3 through the screw feeder 2. The weight of the electronic scale 5 is transmitted to the PLC controller in the form of an electrical signal, and the PLC controller adjusts the speed of the speed regulating motor 2.3 to maintain the weight of the powder material entering the powder feeder 3 and the powder material flowing out of the powder feeder 3. Weight is roughly the same. In this way, a suitable stock of powder raw materials can be maintained in the powder feeder 3, and the uneven delivery of powder raw materials will not be affected due to too much or too little stock, thereby causing instability of the plasma flame. According to the process requirements, the PLC controller can precisely control the conveying amount of powder raw materials by controlling the speed of the servo motor 3.4.

Example 2:

The powder feeding system of a nano-powder preparation process as described in Example 1 is different from Example 1:

As shown in Figures 7 and 8, a second shaft sleeve 3.9 made of nylon or tetrafluoroethylene is arranged between the shaft hole and the shaft 3.2, and a vent hole is provided on the second shaft sleeve 3.9, which is connected to the second high-pressure gas Road 3.13 is connected. A high-pressure working gas is introduced into the second high-pressure air passage 3.13, and the high-pressure working gas enters the shaft hole and the sealing ring through the vent hole to prevent the powder material from entering into it.

In order to enhance the sealing performance, the technical solution is further improved, and the rotating shaft 3.2 and the servo motor 3.4 are non-contactingly connected through a second magnetic coupling transmission wheel. The second magnetic coupling transmission wheel includes a second driving wheel and a second driven wheel, and magnetic coupling magnets are respectively arranged in the second driving wheel and the second driven wheel. The second driving wheel is connected with the servo motor 3.4 through the reducer, and the second driven wheel is connected with the rotating shaft 3.2. A sealing end cover is arranged between the second driving wheel and the second driven wheel, and the sealing end cover is sealingly connected with the lower end surface of the bottom plate of the powder feeding bucket 3.1. It is easy to see from the figure that the bottom plate of the powder feeding bucket 3.1 is in a sealed state, which solves the problem of leakage when the rotating shaft 3.2 is connected to the servo motor 3.4 for transmission.

Example 3:

The powder feeding system of a nano-powder preparation process as described in Example 1 is different from Example 1:

As shown in Figure 9, on the inner cavity wall of the powder feeding bucket 3.1, an L-shaped spring plate 8 is connected by a fixing pin, and a through hole is provided in the spring plate 8, and the through hole is sleeved on the rotating shaft 3.2. A wedge-shaped block 9 is connected to the spring plate 8 , the wedge-shaped block 9 is provided with a wedge-shaped surface, and a vibration block 10 is connected to the free end of the spring plate 8 . When the rotating shaft 3.2 rotates, the stirring rod 3.6 is in sliding contact with the wedge-shaped surface on the wedge-shaped block 9, so that the free end of the spring plate 8 is lifted upwards. As the stirring rod 3.6 continues to rotate, the wedge-shaped surface on the wedge-shaped block 9 is out of contact with the stirring rod 3.6 again. Under the action of elasticity, the vibrating block 10 strikes the powder feeding tray 3.3, and the percussion vibration makes the powder raw material fill up and feed. Via 3.31. It can be seen from the figure that the rapping mechanism in this embodiment and the rapping mechanism in Embodiment 1 can achieve the same effect.

It can be seen from the above three embodiments that the present invention solves the difficult problems of sealing, transmission and transportation of micron-level powder raw materials in the powder feeding process through the positive pressure inflatable sealing structure, the magnetic coupling transmission structure, and the unique quantitative conveying structure. It can stably and accurately control the conveying amount of powder raw materials, so that the plasma flame flow can be stabilized, and then the desired nano-powder particle size can be achieved.

In the process of conveying the powder raw material, the present invention purifies the purity of the conveying gas of the powder raw material, so as to ensure that the powder raw material does not undergo oxidation and nitridation reaction in the high-temperature plasma flame flow; the powder raw material can also be dried and stirred by stirring The mechanism and the rapping mechanism prevent the powder material from arching.

The control device of the present invention can automatically control the whole process of powder feeding, so as to prevent the plasma furnace from causing problems such as unstable feeding or even breaking of feeding. The operator can also grasp the working condition of the powder feeding system at any time.

The parts of the present invention that are not described in detail are prior art. Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, and substitutions can be made in these embodiments without departing from the principle and spirit of the invention and modifications, the scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims (10)

1. a powder feeding system of nano powder preparation technology, is characterized in that: comprise: The silo (1) is connected with a vacuuming device and a working gas refilling device; a material level gauge (1.1) is arranged on the silo (1); The screw feeder (2) is used to transport the powder raw material in the silo (1) to the powder feeder (3), including a feeding pipe (2.1) and a feeding screw (2.2) arranged in the feeding pipe (2.1). ); both ends of the feeding pipe (2.1) are closed, and the feeding port and the discharging port are respectively arranged on the pipe wall near the two ends of the feeding pipe (2.1); the two ends of the feeding screw (2.2) are respectively connected with the feeding pipe. The two closed ends of (2.1) are rotatably connected, and one end of the feeding screw (2.2) is non-contactingly connected to the speed regulating motor (2.3) through the first magnetic coupling transmission wheel (2.4); The powder feeder (3) includes a vertically arranged powder feeding bucket (3.1), and the bottom plate of the powder feeding bucket (3.1) is provided with a discharge hole (3.11), an air inlet hole (3.12) and a shaft hole. The axis is parallel and eccentric to the axis of the powder feeding bucket (3.1), and a rotating shaft (3.2) is rotatably connected in the rotating shaft hole; the end of the rotating shaft (3.2) facing the powder feeding bucket (3.1) is connected with a powder feeding tray (3.3). ), a servo motor (3.4) is connected to the end of the powder feeding bucket (3.1); a powder scraping oil seal is arranged between the upper surface of the powder feeding pan (3.3) and the inner wall of the powder feeding bucket (3.1). A sealing ring is arranged between the lower surface of the disc (3.3) and the bottom plate of the powder feeding bucket (3.1); the diameter of the powder feeding disc (3.3) is larger than the inner diameter of the powder feeding bucket (3.1), and the There are a plurality of feeding through holes (3.31) arranged in the circumferential direction of the powder feeding bucket (3.3); when the powder feeding disc (3.3) rotates, the feeding through holes (3.31) and the discharging holes (3.11), the feeding holes (3.11) and the feeding Air holes (3.12) correspond to communication; The flexible pinch valve (4) includes a vertically arranged rubber tube (4.1), and two pairs of clamping rods (4.2) for clamping or loosening the rubber tube (4.1) are arranged on both sides of the rubber tube (4.1). The clamping rods (4.2) are arranged up and down; each pair of clamping rods (4.2) is connected with the electric push rod (4.3); the discharge end of the rubber tube (4.1) is provided with a gas nozzle (4.4), and the gas nozzle (4.4) Connected with vacuuming device and working gas refilling device; The electronic scale (5) is used for weighing the powder raw material in the powder feeder (3); The discharge port of the silo (1) is connected with the feed port of the screw feeder (2) through the flexible pinch valve (4), and the discharge port of the screw feeder (2) is connected to the powder feeder through the flexible bellows (6). The feed end of the device (3) is connected; The control device is connected with the silo (1), the screw feeder (2), the powder feeder (3), the flexible pinch valve (4) and the electronic scale (5). 2. The powder feeding system of a nano-powder preparation process according to claim 1, characterized in that: the silo (1) is provided with a material level observation window (1.2), and is also provided with a material level observation window ( 1.2) A camera (1.3) for observing the material level; the lower part of the silo (1) is provided with an arch-breaking gas nozzle (1.4) for preventing the powder raw material from arching, and the arch-breaking gas nozzle (1.4) is connected with the working gas. 3. The powder feeding system of a nano powder preparation process according to claim 1, wherein the first magnetic coupling transmission wheel (2.4) comprises a first driving wheel and a first driven wheel, and the first magnetic coupling transmission wheel (2.4) comprises a first driving wheel and a first driven wheel. The driving wheel and the first driven wheel are respectively provided with magnetic coupling magnets; the first driving wheel is connected with the speed regulating motor (2.3) through the reducer, and the first driven wheel is connected with the feeding screw (2.2). 4. The powder feeding system according to claim 1, wherein the two ends of the feeding screw (2.2) pass through the first shaft sleeve (2.5) and the feeding tube (2.1) respectively. The two closed ends are connected in rotation; the material of the first bushing (2.5) is nylon or tetrafluoroethylene; the feeding tube (2.1) is provided with a first high-pressure gas to prevent the powder material from entering the first bushing (2.5). The first high-pressure air passage (2.11) is filled with high-pressure working gas. 5. The powder feeding system according to claim 1, characterized in that: an axial stirring shaft (3.5) is connected to one end of the rotating shaft (3.2) toward the powder feeding barrel (3.1). , also connected with several radial stirring rods (3.6). 6. The powder feeding system of a nano powder preparation process according to claim 5, wherein a vertically arranged guide column (3.7) is connected to the inner cavity wall of the powder feeding barrel (3.1). A vibrating hammer (3.8) is slidably connected to the column (3.7); the vibrating hammer (3.8) is provided with a wedge-shaped surface (3.81). The surface (3.81) slides into contact, so that the vibrating hammer (3.8) moves up and down and strikes the powder feeding tray (3.3). 7. The powder feeding system of claim 1, wherein the bottom plate of the powder feeding barrel (3.1) is provided with a second high-pressure air channel for preventing powder raw materials from entering the shaft hole (3.13), a high-pressure working gas is introduced into the second high-pressure air passage (3.13). 8. The powder feeding system of a nano-powder preparation process according to claim 7, characterized in that: a second shaft sleeve (3.9) made of nylon or tetrafluoroethylene is arranged between the shaft hole and the shaft (3.2). ), a vent hole is provided on the second shaft sleeve (3.9), and the vent hole communicates with the second high-pressure air passage (3.13). 9. The powder feeding system of a nano-powder preparation process according to claim 1 or 8, wherein the rotating shaft (3.2) and the servo motor (3.4) are in non-contact through a second magnetic coupling transmission wheel connection; the second magnetic coupling transmission wheel includes a second driving wheel and a second driven wheel, and magnetic coupling magnets are respectively arranged in the second driving wheel and the second driven wheel; the second driving wheel is connected to the servo motor through the reducer (3.4) connection, the second driven wheel is connected with the rotating shaft (3.2); a sealing end cover is arranged between the second driving wheel and the second driven wheel, and the sealing end cover is sealed with the lower end surface of the bottom plate of the powder feeding bucket (3.1) . 10. The powder feeding system of a nano-powder preparation process according to claim 1, characterized in that: a glass window cover (3.14) is sealed and connected to the upper end of the powder feeding barrel (3.1), and a glass window cover (3.14 ) is provided with a feeding port, and the flexible bellows (6) is communicated with the feeding port on the glass window cover (3.14); in the barrel wall of the powder feeding barrel (3.1), there is a heating device for drying powder raw materials Tube (3.15).

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