CN101279371A - A method and device for preparing micro-uniform particles by harmonic method - Google Patents

Abstract

The invention discloses a method for preparing micro-uniform particles by using a harmonic method, which comprises the following steps: (1) adding metal materials to be smelted into a crucible; (2) adding cooling liquid into a collecting device, and sealing the vacuum chamber; (3) evacuate the crucible and the vacuum chamber, and fill it with protective gas; (4) melt the metal material in the crucible; (5) turn on the piezoelectric oscillator; (6) calculate the (7) The charged main droplet and micro-droplet are separated when passing through the deflection electric field; (8) The main droplet and the micro-droplet are separated by the deflection plate and fall into their respective collection devices. The device and method for preparing micro-uniform particles of the present invention have strong process controllability, can directly obtain uniform particles with smaller sizes, have short process flow, good product quality, and greatly reduce equipment investment.

Description

A method and device for preparing micro-uniform particles by harmonic method

technical field

The invention relates to the technical field of micro-particle preparation, in particular to a method and device for preparing micro-uniform particles using a harmonic method, which utilizes harmonic oscillation to control jet fracture to obtain micro-spherical droplets or particles.

Background technique

Chun and Passow from the Massachusetts Institute of Technology (MIT) proposed a new uniform droplet production method based on Rayleigh's capillary flow instability theory - uniform droplet ejection technology. By controlling the fracture behavior of the continuous molten metal jet, this technology can obtain spherical metal droplets or particles with uniform size. Compared with the traditional particle preparation method, it has the advantages of short process flow, good controllability, low equipment investment, high production efficiency and high product quality. Good quality and other characteristics. On the basis of this technology, Wu Ping, Zhang Shaoming and others applied for Chinese patents (CN2649227, CN1899732) respectively. However, due to the limitation of Rayleigh jet stability conditions, the diameter of particles produced by uniform droplet injection technology is about 1.5 to 2.5 times the diameter of the nozzle. Cause nozzle clogging and jet instability. Therefore, the particle diameters produced by the current uniform droplet jetting technology are mainly in the range of 50 microns to 1000 microns.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings of the prior art, to provide a kind of process controllable, can directly obtain uniform particles with smaller size, short process flow, good product quality, and greatly reduce equipment investment. Method and device for preparing micro-uniform particles by wave method.

A kind of method adopting harmonic method to prepare micro-uniform particle of the present invention, it comprises the following steps:

(1) Open the upper cover of the crucible, add the metal material to be smelted into the crucible, and seal it;

(2) Add cooling liquid into the collection device, move the baffle to the top of the collection device, and seal the vacuum chamber;

(3) evacuate the crucible and the vacuum chamber, and fill it with an inert protective gas;

(4) heat the crucible, melt the metal material in the crucible, and keep warm for 20-30 minutes after the metal material is melted;

(5) Turn on the piezoelectric oscillator so that its frequency is 6-15KH _Z and the frequency ratio is 2-4, apply a voltage of 200-300V to the electrode plate, and use the pressure control system to stabilize the crucible and the vacuum chamber The pressure difference is 0.5-1.5P ₀ , so that the molten metal is ejected from the nozzle at the bottom of the crucible in the form of a laminar jet. Under the action of the vibrating head of the piezoelectric oscillator, the outflowing metal jet breaks into larger main droplets and Smaller micro-droplets, when passing through the gap between the electrode plates, the two sizes of droplets are respectively charged with the same amount of charge;

(6) The droplet image captured by the image monitoring system is combined with the computer image analysis system to accurately calculate the diameter of the droplet, so as to feedback control and adjust the frequency generated by the piezoelectric oscillator, so as to obtain a uniform droplet of a set size, At the same time, the computer analysis system calculates the electricity of the droplet, so as to control the loading parameters of the electrode plate;

(7) The charged main droplets and microdroplets are separated when passing through the deflection electric field;

(8) When the droplet reaches the set size, the baffle plate is removed, and the main droplet and micro-droplet are separated by the deflection plate and fall into their respective collection devices, and finally solidified and formed by the cooling liquid.

A device for implementing the method of claim 1, comprising:

(a) a vacuum chamber, which is connected to a vacuum pump by a first gas delivery pipe provided with a vacuum valve;

(b) a microcomputer control system, which comprises a main board, which is connected to a signal generator and an image acquisition card on the main board by control lines respectively;

(c) a frequency divider, which is installed on the side wall of the vacuum chamber and connected to the frequency divider through a wire, and the frequency divider is connected to the signal generator in the microcomputer control system ;

(d) an imaging device, which is installed on the side wall of the vacuum chamber opposite to the strobe and is connected with the image acquisition card in the microcomputer control system by a wire.

(e) a crucible, the crucible is arranged on the top of the vacuum chamber, the bottom of the crucible is inlaid with micro nozzles, the outer wall of the crucible is equipped with a heater, the crucible has a built-in temperature measuring element, The temperature measuring element and the heater are respectively connected to the temperature control device through the control line;

(f) a piezoelectric oscillator, the vibrating head of the piezoelectric oscillator is arranged in the crucible and is located on the upper part of the nozzle, and a piezoelectric oscillator is installed between the piezoelectric oscillator and the crucible cover. Up and down adjustment device;

(g) an electrode-adding plate, the electrode-adding plate is arranged in the vacuum chamber and is positioned under the outside of the micro-nozzle, and an opening is arranged in the middle of the electrode-adding plate relative to the nozzle;

(h) Two deflection plates arranged in parallel, the deflection plates are arranged in the vacuum chamber and below the described electrode addition plate, and the electrode addition plate and the deflection plate are respectively connected to the power supply through wires , the power supply is connected to the main board in the microcomputer control system through wires;

(i) two collection devices, which are arranged in the vacuum chamber and below the deflection plate;

(j) a baffle rotatable around the baffle bracket and positioned between said deflection plate and the collecting means;

(k) an inert gas storage device, the gas storage device is respectively connected to the crucible and the vacuum chamber through the second and third gas delivery pipes on which the first and second valves are housed;

(l) an air pressure controller, which is connected to the first and second valves through the first and second control lines respectively, and the two pressure sensors of the air pressure controller are respectively placed in the crucible and vacuum chamber interior.

The micro-uniform particle preparation device and method of the present invention have strong process controllability, can control the temperature of the crucible, the pressure difference between the crucible and the vacuum chamber, and can also control the jet flow rate and the distance between the piezoelectric oscillator and the small hole of the nozzle. Perturbation amplitude. The signal generator is used to provide harmonic signals to the piezoelectric oscillator, so as to control the periodic breakage of the jet into the main droplet and the micro-droplet, which is charged when passing through the electrode plate, and the main particle and the micro-particle follow different trajectories when passing through the deflection electric field. Falling into their respective collection devices, particles with microscopic dimensions are obtained. Compared with other methods for preparing granules at present, the invention can directly obtain uniform granules with smaller sizes, has short process flow, good product quality and greatly reduces equipment investment.

Description of drawings

The accompanying drawing is a schematic diagram of the structure of the device for preparing micro-uniform particles using the harmonic method of the present invention.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

A method for preparing micro-uniform particles using a harmonic method of the present invention comprises the following steps: (1) opening the crucible upper cover, adding metal materials to be smelted into the crucible, and sealing it; (2) pouring the cooling liquid Add to the collection device, move the baffle to the top of the collection device, and seal the vacuum chamber; (3) evacuate the crucible and the vacuum chamber, and fill it with an inert protective gas; (4) heat the crucible and melt the crucible The metal material in the pot is kept warm for 20-30 minutes after the metal material is melted; (5) Turn on the piezoelectric oscillator to make the frequency _6-15KHZ , the frequency ratio is 2-4, and apply a voltage of 200 to the electrode plate -300V, use the pressure control system to achieve a stable pressure difference of 0.5-1.5P ₀ between the crucible and the vacuum chamber, so that the molten metal is ejected from the nozzle at the bottom of the crucible in the form of a laminar jet, and the signal generator provides harmonics The signal is sent to the piezoelectric oscillator. Under the action of the vibration head of the piezoelectric oscillator, the outflowing metal jet breaks into larger main droplets and smaller microdroplets. When passing through the gap between the electrode plates, the two sizes The droplets are respectively charged with the same amount of charge; (6) The diameter of the droplet is accurately calculated by using the droplet image taken by the image monitoring system combined with the computer image analysis system, so as to feedback control and adjust the frequency generated by the piezoelectric oscillator, thereby Obtain uniform droplets with a set size, and at the same time, the computer analysis system calculates the electricity of the droplets, thereby controlling the loading parameters of the electrode plate; (7) The charged droplets are divided into extremely small droplets and larger droplets when passing through the deflection electric field (8) When the droplet reaches the set size, the baffle plate is removed, and the very small droplet and the larger droplet are separated by the deflection plate and fall into their respective collection devices, and finally solidified and formed by the cooling liquid.

The principle of the method of the present invention is: use an inert gas (such as nitrogen) to inject into the crucible and the vacuum chamber, use the pressure control system to make the crucible and the vacuum chamber reach a stable pressure difference, and make the metal melt flow from the micro nozzle at the bottom of the crucible It is ejected in the form of laminar jet. According to the principle of Rayleigh jet instability, the harmonic vibration generated by the piezoelectric oscillator is used to disturb the metal jet, so that the metal jet is broken into uniform main droplets and micro droplets. The real-time size parameters of the generated droplets are obtained through the monitoring system combined with the computer analysis system, and then for the optimized parameters, the frequency of the oscillator is feedback-controlled to reduce the error between the generated metal droplets and the set droplet size. The metal droplet is charged by induction when it is added to the electrode plate, and the charged main droplet and micro-droplet are separated by the deflection electric field and enter their respective collection devices.

As shown in the figure, the device of the present invention includes a crucible 1, a piezoelectric oscillator 2, a piezoelectric oscillator up and down adjustment device 39, an electrode plate 6, a deflection plate 8, a baffle 9, a baffle support 10, and a collection device 11 and 12. A piezoelectric oscillator 2 is arranged on the crucible 1, and the piezoelectric oscillator 2 is connected to a signal generator 36 through a control line. The bottom of the crucible 1 is inlaid with a micro nozzle 5, and the vibrating head 3 of the piezoelectric oscillator 2 is set On the top of micropore 5, there is heater 4 on the outer wall of crucible 1, there is electrode plate 6 under the outside of micro nozzle 5, there is an opening 7 in the middle of electrode plate 6 relative to the nozzle, and electrode plate 6 is arranged below Parallel deflection plates 8 . The bottom of the vacuum chamber 13 is provided with particle cooling collection devices 11 and 12, and a baffle plate 8 is arranged on the collection devices 11 and 12, which is fixed on the bottom of the vacuum chamber 13 by a bracket 10, and the baffle plate 8 can rotate around the bracket 10. The side wall of the crucible 1 and the side wall of the vacuum chamber 13 are connected with the second and third gas delivery pipes 15 and 16 respectively, and the gas delivery pipes 15 and 16 are connected with the valves 17 and 18 respectively, and are connected with the valve 37 through the fourth gas delivery pipe 19, and then It is connected with the inert gas storage device 14 , and the first and second valves 17 and 18 are connected with the air pressure controller 33 through the control lines 21 and 20 . The air pressure controller 21 has two pressure sensors 22 and 23 placed inside the crucible 1 and the vacuum chamber 12 respectively. The right side of the vacuum chamber 11 is connected to the vacuum valve 24 through the first gas delivery pipe 31 and connected to the vacuum pump 25 through the gas delivery pipe 32 . The built-in temperature measuring element in the crucible 1 can be a thermocouple 38, which is connected to the temperature control device 30 through a connection line, and the heater 4 is connected to the temperature control device 30 through a control line. The adding electrode plate 6 and the deflecting electrode plate 8 are respectively connected to the power supply 40 through connecting wires. The power supply 40 is connected with the main board 35 in the microcomputer control system by wiring. There is a strobe 26 on the left side wall of the vacuum chamber 13, which is connected to the frequency divider 28 by a wire, and the frequency divider 28 is connected to the signal generator 36 in the microcomputer control system 29 . On the right side of the vacuum chamber 11 opposite to the strobe 26, there is an imaging device 27, which is connected with the image acquisition card 34 in the microcomputer control system 29 by wiring. The main components of the microcomputer control system 29 include a signal generator 36 , an image acquisition card 34 and a main board 35 . The signal generator 36 and the image acquisition card 34 are respectively connected to the microcomputer main board 35 through control lines. The micro nozzle is preferably a circular sapphire hole with a diameter ranging from 0.03 to 0.5 mm. The sapphire material is resistant to high temperature and has little deformation. The distance between the nozzle and the vibration head is preferably 0.3mm-2mm.

Example 1

(1) Open the upper cover of the crucible, add 100g of metal material Sn-3.5Ag-0.5Cu to be smelted in the crucible, and seal it;

(2) Add cooling liquid into the collection device, move the baffle to the top of the collection device, and seal the vacuum chamber;

(3) vacuumize the crucible and the vacuum chamber, and fill it with nitrogen;

(4) Heating the crucible, melting the metal material in the crucible, and keeping warm for 20 minutes after the metal material is melted;

(5) Turn on the piezoelectric oscillator to generate harmonic vibration with a main frequency of 5KH _Z and a frequency ratio of 4, apply a voltage of 250V to the electrode plate, and use the pressure control system to stabilize the crucible and the vacuum chamber The pressure difference is 1.3P ₀ , so that the molten metal is ejected from the nozzle at the bottom of the crucible in the form of a laminar jet. Each droplet is charged with an equal amount of charge when passing through the gap between the electrode plates, the distance between the nozzle and the vibrating head is 2mm, and the nozzle is a circular sapphire hole with a diameter of 0.1mm;

(6) The droplet image taken by the image monitoring system is combined with the computer image analysis system to accurately calculate the diameter of the droplet, wherein the diameter of the very small droplet is 0.06mm, and the diameter of the larger droplet is 0.2mm. Therefore, the feedback control adjusts the frequency generated by the piezoelectric oscillator to 8.6KH _Z , so as to obtain extremely small droplets with a set diameter of 0.04mm and larger droplets with a diameter of 0.18mm. At the same time, the computer analysis system calculates the droplet size Electricity, so as to control the loading parameter of the electrode plate to be 300V;

(7) The charged droplets are divided into extremely small droplets and larger droplets when passing through a deflection electric field with a voltage of 50V;

(8) When the droplet reaches the set size, the baffle plate is removed, and the very small droplet and the larger droplet are separated by the deflection plate and fall into their respective collection devices, and finally solidified and formed by the cooling liquid.

Example 2

(1) Open the crucible loam cake, add the metal material Sn-5%Pb that needs melting in the crucible, and seal;

(2) Add cooling liquid into the collection device, move the baffle to the top of the collection device, and seal the vacuum chamber;

(3) vacuumize the crucible and the vacuum chamber, and fill it with nitrogen;

(4) Heating the crucible, melting the metal material in the crucible, and keeping warm for 30 minutes after the metal material is melted;

(5) Turn on the piezoelectric oscillator to generate harmonic vibration with a main frequency of _12KHZ frequency ratio of 2, apply a voltage of 300V to the electrode plate, and use the pressure control system to achieve a stable pressure between the crucible and the vacuum chamber. The difference is 1.5P ₀ , so that the molten metal is ejected from the nozzle at the bottom of the crucible in the form of a laminar jet. Under the action of the vibrating head of the piezoelectric oscillator, the outflowing metal jet breaks into extremely small droplets and larger droplets. , when passing through the middle gap of the electrode plate, each droplet is charged with an equal amount, the distance between the nozzle and the vibrating head is 1.0mm, and the nozzle is a circular sapphire hole with a diameter of 0.05mm;

(6) Utilize the droplet image taken by the image monitoring system combined with the computer image analysis system to accurately calculate the diameter of the droplet, wherein the diameter of the very small droplet is 0.02mm, and the diameter of the larger droplet is 0.08mm, Therefore, the feedback control adjusts the frequency generated by the piezoelectric oscillator to _11.4KHZ , so as to obtain extremely small droplets with a set diameter of 0.02mm and larger droplets with a diameter of 0.1mm. At the same time, the computer analysis system calculates the droplet size. Electricity, so as to control the loading parameter of the electrode plate to be 200V;

(7) The charged droplets are divided into extremely small droplets and larger droplets when passing through a deflection electric field with a voltage of 20V;

(8) When the droplet reaches the set size, the baffle plate is removed, and the very small droplet and the larger droplet are separated by the deflection plate and fall into their respective collection devices, and finally solidified and formed by the cooling liquid.

Example 3

(1) Open the crucible loam cake, add the metallic material Sn-9%Zn that needs melting in the crucible, and seal;

(2) Add cooling liquid into the collection device, move the baffle to the top of the collection device, and seal the vacuum chamber;

(3) vacuumize the crucible and the vacuum chamber, and fill it with nitrogen;

(4) heat the crucible, melt the metal material in the crucible, and keep warm for 25 minutes after the metal material is melted;

(5) Turn on the piezoelectric oscillator to generate harmonic vibration with a main frequency of 14KH _Z and a frequency ratio of 3, apply a voltage of 300V to the electrode plate, and use the pressure control system to stabilize the crucible and the vacuum chamber The pressure difference is 1P ₀ , so that the molten metal is ejected from the nozzle at the bottom of the crucible in the form of a laminar jet. Under the action of the vibrating head of the piezoelectric oscillator, the outflowing metal jet breaks into extremely small droplets and larger droplets. , when passing through the middle gap of the electrode plate, each droplet is charged with the same amount of charge, the distance between the nozzle and the vibrating head is 0.3mm, and the nozzle is a circular sapphire hole with a diameter of 0.5mm;

(6) The droplet image taken by the image monitoring system is combined with the computer image analysis system to accurately calculate the diameter of the droplet, wherein the diameter of the very small droplet is 0.06mm, and the diameter of the larger droplet is 0.68mm. Therefore, the feedback control adjusts the frequency generated by the piezoelectric oscillator to _15KHZ , so as to obtain extremely small droplets with a set diameter of 0.05mm and larger droplets with a diameter of 0.65mm. At the same time, the computer analysis system calculates the electricity of the droplets , so as to control the loading parameter of the electrode plate to be 100V;

(7) The charged droplets are divided into extremely small droplets and larger droplets when passing through a deflection electric field with a voltage of 30V;

(8) When the droplet reaches the set size, the baffle plate is removed, and the very small droplet and the larger droplet are separated by the deflection plate and fall into their respective collection devices, and finally solidified and formed by the cooling liquid.

Claims (6)

1. method that adopts harmonic method to be equipped with micro-uniform grain is characterized in that it may further comprise the steps:

(1) opens the crucible loam cake, in crucible, add metal material that needs melting and sealing;

(2) cooling fluid is added in the gathering-device, baffle plate is moved to the top of gathering-device and sealed vacuum chamber;

(3) crucible and vacuum chamber are vacuumized, and charge into inert protective gas;

(4) heating crucible, the metal material in the melting cup, and metal material fusing back insulation 20-30 minute;

(5) opening piezoelectric oscillator, to make its frequency be 6-15KH _Z, frequency ratio is 2-4, gives to add battery lead plate and add voltage 200-300V, utilize control pressurer system to make and reach between crucible and the vacuum chamber and stablize pressure reduction 0.5-1.5P ₀Thereby motlten metal is penetrated from the nozzle of the crucible bottom form with laminar jet, under the effect of piezoelectric oscillator vibration head, the metal jet that flows out is fractured into bigger main droplet and less little drop, is with the equivalent electric charge respectively at the drop of two kinds of sizes when adding the battery lead plate intermediate gaps;

(6) utilize the captured drop image of image monitoring system to calculate the diameter of drop accurately in conjunction with the computer image analysis system, thereby FEEDBACK CONTROL is adjusted the frequency that piezoelectric oscillator produces, thereby obtain to set the symmetrical liquid drop of size, the simultaneous computer analytical system calculates the electric weight of drop, thereby control adds the loading parameters of battery lead plate;

(7) charged main droplet separates through deflecting electric field the time with little drop;

(8) when drop reaches the size of setting, remove baffle plate, minimum drop separates through the deflection pole plate with bigger drop and falls into its gathering-device separately, by the moulding of cooling fluid final set.

2. employing harmonic method according to claim 1 is equipped with the method for micro-uniform grain, it is characterized in that: the distance between described nozzle and the described vibration head is 0.3mm-2mm.

3. employing harmonic method according to claim 1 is equipped with the method for micro-uniform grain, it is characterized in that: described nozzle is circular sapphire aperture, and its diameter range is between 0.030～0.500mm.

4. device of realizing the described method of claim 1 is characterized in that it comprises:

(a) vacuum chamber, this vacuum chamber links to each other with vavuum pump by first appendix that it is provided with vacuum valve;

(b) Control System of Microcomputer, this Control System of Microcomputer comprises mainboard, is connected signal generator and image pick-up card on the described mainboard by control line respectively;

(c) one is dodged device frequently, and this sudden strains of a muscle frequency device is installed on the sidewall of described vacuum chamber and by line and is connected with frequency divider, and described frequency divider links to each other with signal generator in the Control System of Microcomputer;

(d) camera head, this camera head be installed in the described sidewall that dodges the vacuum chamber of device opposite position frequently on and link to each other with image pick-up card in the Control System of Microcomputer by line.

(e) crucible, this crucible is arranged on the top of described vacuum chamber, and the bottom of this crucible is inlaid with micro nozzle, and its lateral wall is equipped with heater, described crucible is built-in with temperature element, and this temperature element links to each other with temperature regulating device by control line respectively with heater;

(f) piezoelectric oscillator, the vibration head of this piezoelectric oscillator are arranged in the crucible and are positioned at the top of described nozzle, and piezoelectric oscillator up-down adjustment device is housed between described piezoelectric oscillator and crucible cover;

(g) one adds battery lead plate, and this adds the outside below that battery lead plate is arranged in the described vacuum chamber and is positioned at described micro nozzle, with respect to described nozzle place an opening is arranged in the middle of this adds battery lead plate;

(h) two deflection pole plates that be arranged in parallel, this deflection pole plate is arranged in the described vacuum chamber and is positioned at the described battery lead plate below that adds, the described battery lead plate that adds links to each other with power supply by lead respectively with the deflection pole plate, and described power supply links to each other with mainboard in the Control System of Microcomputer by lead;

(i) two gathering-devices, this gathering-device are arranged in the described vacuum chamber and are positioned at the below of described deflection pole plate;

(j) baffle plate, this baffle plate can be around the barrier support rotation and between described deflection pole plate and gathering-device;

(k) inert gas storage facilities, this gaseous storage device link to each other with described crucible, vacuum chamber by second, third appendix that first, second valve is housed on it respectively;

(l) gas pressure regulator, this gas pressure regulator link to each other with described first and second valve by first and second control line respectively, and two pressure sensors of this gas pressure regulator place described crucible and vacuum chamber inside respectively.

5. employing harmonic method according to claim 4 is equipped with the device of micro-uniform grain, it is characterized in that: described nozzle is circular sapphire aperture, and its diameter range is between 0.030～0.500mm.

6. employing harmonic method according to claim 4 is equipped with the device of micro-uniform grain, it is characterized in that: the distance between described nozzle and the described vibration head is 0.3mm-2mm.

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