阅读说明：本技术 雾化喷头、雾化造粉系统和雾化造粉方法 (Atomizing nozzle, atomizing powder making system and atomizing powder making method ) 是由 张得栋 李磊 杨玮婧 袁炜 金政伟 黄河 申宏鹏 刘振盈 丁将敏 于 2021-08-19 设计创作，主要内容包括：本发明涉及聚合物粒料的粉碎领域,具体地涉及雾化喷头、制备聚合物粉末的雾化造粉系统和雾化造粉方法,所述雾化喷头包括第一混合室、可转动的设置在所述第一混合室内腔的剪切组件、第二混合室,气体加速室,所述气体加速室具有外壁和设置在所述外壁内的圆锥状空腔,所述圆锥状空腔的开口与所述第二混合室的出液口连通；雾化喷孔,与所述圆锥状空腔的尖端部连通,且与所述第二混合室的外壁上设置的第三进气通道相连通。本发明提供的制备聚合物粉末的雾化造粉系统能够使气体容易进入聚合物熔体中形成均匀的泡状气液两相流,能够提高聚合物粉末的生产效率和原料成粉率和操作安全性。(The invention relates to the field of crushing of polymer granules, in particular to an atomizing spray head, an atomizing powder-making system for preparing polymer powder and an atomizing powder-making method, wherein the atomizing spray head comprises a first mixing chamber, a shearing assembly, a second mixing chamber and a gas accelerating chamber, the shearing assembly is rotatably arranged in the inner cavity of the first mixing chamber, the gas accelerating chamber is provided with an outer wall and a conical cavity arranged in the outer wall, and the opening of the conical cavity is communicated with a liquid outlet of the second mixing chamber; and the atomization spray hole is communicated with the tip part of the conical cavity and is communicated with a third air inlet channel arranged on the outer wall of the second mixing chamber. The atomization powder making system for preparing the polymer powder can enable gas to easily enter a polymer melt to form uniform bubble-shaped gas-liquid two-phase flow, and can improve the production efficiency, the raw material powder forming rate and the operation safety of the polymer powder.)

1. An atomizer head, characterized in that said atomizer head comprises: a first mixing chamber (14),

the shearing assembly (19) is rotatably arranged in the inner cavity of the first mixing chamber (14) and is used for shearing and mixing the polymer melt introduced into the first mixing chamber (14) and the first heating gas to obtain a bubble-shaped first gas-liquid two-phase flow;

a liquid inlet of the second mixing chamber (22) is communicated with a liquid outlet of the first mixing chamber (14), the second mixing chamber (22) is provided with an outer wall and a cavity arranged in the outer wall, a second air inlet channel (15) is arranged on the outer wall, a plurality of air inlets (21) are arranged on the inner wall of the cavity and used for mixing the first gas-liquid two-phase flow led into the second mixing chamber (22) with second heating gas to obtain a second gas-liquid two-phase flow;

the gas acceleration chamber (25) is provided with an outer wall and a conical cavity arranged in the outer wall, and the opening of the conical cavity is communicated with the liquid outlet of the second mixing chamber (22) and is used for accelerating the second gas-liquid two-phase flow led into the gas acceleration chamber (25) to obtain high-speed fluid; and

and the atomizing spray hole (17) is communicated with the tip of the conical cavity, is communicated with a third air inlet channel (16) arranged on the outer wall of the second mixing chamber (22), and is used for enabling the high-speed fluid to impact with third heating air introduced by the third air inlet channel (16) to obtain atomized liquid drops.

2. An atomizer head according to claim 1, wherein the shearing assembly (19) comprises two meshing gears or screws rotatably arranged in the first mixing chamber (14);

preferably, a mechanical seal, a packing seal or a magnetic seal is used between the drive shaft of the shearing assembly (19) and the first mixing chamber (14).

3. An atomising nozzle according to claim 1 or 2, wherein the top end of the first mixing chamber (14) is provided with a feed inlet (18) for introducing the polymer melt into the first mixing chamber (14);

and a first air inlet channel (13) is arranged on the side wall of the first mixing chamber (14) and used for introducing the first heating air into the first mixing chamber (14).

4. An atomizer according to any one of claims 1 to 3, wherein said inlet orifices (21) are arranged in at least two groups spaced apart in the direction of flow of said first two-phase gas-liquid stream;

preferably, each group of air inlet holes comprises at least two rows of air inlet hole units, and the air inlet hole units of the at least two rows are distributed on the inner wall of the second mixing chamber (22) in a mutually staggered manner;

preferably, each row of the air intake hole unit includes at least four air intake holes.

5. An atomizer head according to any one of claims 1 to 4, wherein the ratio of the height to the diameter of the interior of the second mixing chamber (22) is from 6 to 10: 1;

preferably, the conicity of the conical cavity is 0.8-1.5: 1;

preferably, the length-to-diameter ratio of the atomizing orifice (17) is 0.5 to 5, preferably 3.5 to 4.5: 1.

6. an atomized powder production system for producing a polymer powder, the atomized powder production system comprising:

the feeding unit (1) is used for introducing polymer materials into the system to be melted to obtain polymer melt;

a gas supply unit (6) for providing heating gas for the atomized powder making system;

an atomizing nozzle (2) respectively communicated with the gas supply unit (6) and the feeding unit (1) and used for mixing and spraying the heating gas and the polymer melt to obtain atomized liquid drops, wherein the atomizing nozzle (2) comprises the atomizing nozzle as claimed in any one of claims 1 to 5;

the cooling unit (11) is arranged at the lower end of the atomizing nozzle (2) and is used for cooling the atomized liquid drops to obtain polymer powder;

and the classifying and screening unit (12) is arranged at the lower end of the cooling unit (11) and is used for screening the polymer powder to obtain polymer powder with various particle sizes.

7. The atomized powder making system according to claim 6, wherein a heater (4) is arranged on a pipeline of the gas supply unit (6) communicated with the atomizing nozzle (2) and used for heating gas to obtain heated gas;

preferably, the gas supply unit (6) is in communication with the first feed channel (13), the second feed channel (15) and the third feed channel (16), respectively, through a line (3) provided with a pressure reducing valve (9) for introducing the heated gas into the first feed channel (13), the second feed channel (15) and the third feed channel (16), respectively.

8. The atomized powder making system according to claim 7, wherein a gas metering pump (5) is arranged on a pipeline of the gas supply unit (6) communicated with the atomizing nozzle (2) and used for controlling the flow rate of the gas;

preferably, a gear metering pump (7) is arranged on a pipeline of the feeding unit (1) communicated with the atomizing spray head (2) and is used for controlling the flow rate of the polymer melt;

preferably, the cooling unit (11) comprises a cold source and a spray head, and the cold source is sprayed on the surface of the liquid drops through the spray head to cool the liquid drops.

9. The atomized powder producing system according to any one of claims 6 to 8, wherein the classifying screen unit (12) comprises, from top to bottom, N screens dividing the classifying screen unit (12) into N +1 screen spaces;

preferably, the apertures of the N screens are gradually reduced from top to bottom.

10. An atomized powder forming method for preparing polymer powder is characterized in that polymer materials are introduced into the atomized powder forming system of any one of claims 6 to 9 to be crushed, and polymer powder with various particle sizes is obtained.

Technical Field

The invention relates to the field of crushing of polymer granules, in particular to an atomizing spray head, an atomizing powder-making system for preparing polymer powder and an atomizing powder-making method.

Background

The 3D printing technology is known as another great discovery following a steam engine, a computer, and the internet, and is an advanced manufacturing technology leading the third industrial revolution. Compared with the traditional manufacturing processes such as casting and cutting, the 3D printing process has the advantages of high material utilization rate, no need of mold support, quick manufacturing aging, complex printing model, high precision and the like. The high polymer material is prepared into solution, silk or powder and the like for a corresponding 3D printing process, wherein the Selective Laser Sintering (SLS) technology is used for selectively sintering the laid powder material layer by taking a laser beam as an energy source to obtain the three-dimensional solid part.

At present, the preparation methods of 3D printing powder for laser sintering mainly include a solvent precipitation method, a solution dispersion method, a direct polymerization method, and a mechanical pulverization method, wherein the mechanical pulverization method is one of the methods, but the prepared powder has a low sphericity and cannot be continuously produced. A preparation process with high powder preparation efficiency and good powder sphericity is needed, but the prepared powder has low sphericity and cannot be produced continuously. A preparation process with high powder preparation efficiency and good powder sphericity is needed.

CN103372509A discloses a solid cone-shaped bubble atomizing nozzle suitable for high-viscosity non-newtonian fluid, which is a method of injecting a small amount of gas into liquid at the upstream of the nozzle outlet to form bubble-shaped gas-liquid two-phase flow, and atomizing the liquid by utilizing acceleration, deformation and expansion of bubbles in the flowing and spraying processes to form small droplets, but in the method, the polymer melt and the gas are not uniformly mixed, and the polymer melt and the gas generate a layering phenomenon.

CN106216126A discloses a bubble atomizing nozzle suitable for shear thinning non-newtonian fluid, which introduces layer-by-layer injection of gas to facilitate the generation of uniform bubble flow, and introduces an external rotating air flow at the nozzle outlet to suppress the fluctuation intensity of bubble flow, thereby improving the stability of jet flow. The high molecular polymer melt belongs to non-Newtonian fluid, and due to the large surface tension and viscous force, the atomization effect is not ideal by adopting the existing atomization nozzle, the polymer melt and gas are easily layered, and particles with centralized particle size distribution and controllable morphology cannot be formed.

Disclosure of Invention

The invention aims to solve the problems that the atomization effect of a high-molecular polymer melt is not ideal and particles with centralized particle size distribution and controllable morphology cannot be formed in the prior art, and provides an atomization powder-making system and an atomization powder-making method for preparing polymer powder.

In order to achieve the above object, a first aspect of the present invention provides an atomizer head comprising: the first mixing chamber is provided with a first mixing chamber,

the shearing assembly is rotatably arranged in the inner cavity of the first mixing chamber and is used for shearing and mixing the polymer melt introduced into the first mixing chamber and the first heating gas to obtain a bubble-shaped first gas-liquid two-phase flow;

a liquid inlet of the second mixing chamber is communicated with a liquid outlet of the first mixing chamber, the second mixing chamber is provided with an outer wall and a cavity arranged in the outer wall, a second air inlet channel is arranged on the outer wall, and a plurality of air inlets are arranged on the inner wall of the cavity and used for mixing the first gas-liquid two-phase flow with second heating gas to obtain a second gas-liquid two-phase flow;

the gas acceleration chamber is provided with an outer wall and a conical cavity arranged in the outer wall, and an opening of the conical cavity is communicated with a liquid outlet of the second mixing chamber and is used for accelerating the second gas-liquid two-phase flow to obtain high-speed fluid; and

and the atomization spray hole is communicated with the tip part of the conical cavity, is communicated with a third air inlet channel arranged on the outer wall of the second mixing chamber, and is used for impacting the high-speed fluid with third heating air introduced by the third air inlet channel to obtain atomized liquid drops.

A second aspect of the present invention provides an atomized powder system for producing a polymer powder, the atomized powder system comprising:

the feeding unit is used for introducing polymer materials into the system for melting to obtain polymer melt;

the gas supply unit is used for providing heating gas for the atomization powder making system;

the atomizing nozzle is respectively communicated with the gas supply unit and the feeding unit and is used for mixing and spraying the heating gas and the polymer melt to obtain atomized liquid drops, and the atomizing nozzle comprises the atomizing nozzle in the first aspect;

the cooling unit is arranged below the atomizing nozzle and used for cooling the atomized liquid drops to obtain polymer powder;

and the classifying and screening unit is arranged below the cooling unit and is used for screening the polymer powder to obtain polymer powder with various particle sizes.

In a third aspect of the present invention, an atomized powder-making method for preparing polymer powder is provided, wherein polymer materials are introduced into the atomized powder-making system of the second aspect and are crushed to obtain polymer powder with various particle sizes.

Through the technical scheme, the atomization powder making system for preparing the polymer powder can enable gas to easily enter a polymer melt to form uniform bubble-shaped gas-liquid two-phase flow, form polymer powder with centralized particle size distribution and controllable morphology, can continuously produce, improve the production efficiency, the raw material powder yield and the operation safety of the polymer powder, and can be used as laser sintering 3D printing powder.

Drawings

FIG. 1 is a schematic structural view of an atomizer according to an embodiment of the present invention;

FIG. 2 is a left side view of an atomizer head for producing polymer powder in accordance with one embodiment of the present invention;

fig. 3 is a schematic structural diagram of an atomized powder forming system for preparing polymer powder according to an embodiment of the present invention.

Description of the reference numerals

1. Feeding unit 2, atomizer

3. Pipeline 4, heater

5. Gas metering pump 6 and gas supply unit

7. Gear metering pump 8 and control unit

9. Pressure reducing valve 10, analysis unit

11. Cooling unit 12 and classifying and screening unit

13. First air inlet passage 14, first mixing chamber

15. Second air intake passage 16, third air intake passage

17. Atomizing orifice 18 and feed inlet

19. Shearing assembly 21, air inlet

22. Second mixing chamber 221, outer wall of second mixing chamber

25. Gas acceleration chamber 251, gas acceleration chamber outer wall

26. Shaft sealing motor

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

In the present invention, the use of directional terms such as "upper, lower, left, right" generally means upper, lower, left, right as viewed with reference to the accompanying drawings, unless otherwise specified; "inner and outer" generally refer to the inner and outer relative to the profile of the components themselves; "distal and proximal" generally refer to distance relative to the contour of the components themselves.

Fig. 1 is a schematic structural diagram of an atomizer according to an embodiment of the present invention, and a first aspect of the present invention provides an atomizer comprising: a first mixing chamber 14;

the shearing assembly 19 is rotatably arranged in the inner cavity of the first mixing chamber 14 and is used for shearing and mixing the polymer melt introduced into the first mixing chamber 14 and the first heating gas to obtain a bubble-shaped first gas-liquid two-phase flow;

a liquid inlet of the second mixing chamber 22 is communicated with a liquid outlet of the first mixing chamber 14, the second mixing chamber 22 is provided with an outer wall and a cavity arranged in the outer wall, a second air inlet channel 15 is arranged on the outer wall, and a plurality of air inlets 21 are arranged on the inner wall of the cavity and used for mixing the first gas-liquid two-phase flow with the second heating gas to obtain a second gas-liquid two-phase flow;

the gas acceleration chamber 25 is provided with an outer wall and a conical cavity arranged in the outer wall, and an opening of the conical cavity is communicated with a liquid outlet of the second mixing chamber 22 and is used for accelerating the second gas-liquid two-phase flow to obtain a high-speed fluid; and

and the atomizing spray hole 17 is communicated with the tip end of the conical cavity, is communicated with a third air inlet channel 16 arranged on the outer wall of the second mixing chamber 22, and is used for enabling the high-speed fluid to impact with third heating air introduced by the third air inlet channel 16 to obtain atomized liquid drops.

In the invention, a polymer melt and a first heating gas firstly enter a first mixing chamber 14, and the first heating gas enters the polymer melt under the shearing action of a shearing assembly 19 to form a bubble-shaped first gas-liquid two-phase flow; then the bubble-shaped first gas-liquid two-phase flow enters a second mixing chamber 22 and contacts with second heating gas from a gas inlet 21 to form a more uniform second gas-liquid two-phase flow with bubbles; after entering the gas acceleration chamber 25, the second gas-liquid two-phase flow is accelerated under the action of centrifugal force to obtain high-speed fluid, and when the high-speed fluid flows out of the gas acceleration chamber 25, the pressure of the high-speed fluid is suddenly reduced and simultaneously impacted by third heating gas from the third gas inlet channel 16, the high-speed fluid is crushed to form atomized liquid drops, and the atomized liquid drops are sprayed out from the atomization spray hole 17.

According to the invention, the shearing module 19 preferably comprises two meshing gears or screws rotatably arranged in the first mixing chamber 14. When the shearing assembly is a gear, the gear can be an electric meshing gear, and the outer diameter of the gear is 20-30mm, for example, 20mm, 22mm, 25mm, 30mm or any integer in the range formed by any two of the above numerical values; the number of teeth is 22-28, and may be, for example, 22, 24, 26, 28, or any integer in the range of any two of the above values; under the preferable conditions, the defects that the surface tension of the high molecular polymer melt is large, the viscosity is strong, and the high molecular polymer melt and the first heating gas are not easy to form uniform gas-liquid two-phase flow can be overcome, so that the polymer melt and the first heating gas are mixed more fully, the more uniform first gas-liquid two-phase flow is formed, the sphericity of the polymer powder is improved, and the particle size of the polymer powder is reduced. The two meshed gears or screws can rotate in the same direction or in opposite directions.

In some preferred embodiments of the present invention, a mechanical seal, a packing seal or a magnetic seal is used between the drive shaft of the shearing assembly 19 and the first mixing chamber 14; in the above preferred embodiment, the first mixing chamber 14 is in a closed high-pressure state, so that the surface viscosity of the polymer melt is further reduced and a large number of pores are generated in the polymer melt during the mechanical shearing process of the shearing assembly 19, which helps the first heating gas to enter the polymer melt to form a more uniform bubble-shaped gas-liquid two-phase flow.

According to the invention, the first mixing chamber 14 preferably has an outer wall and a cavity arranged inside the outer wall, the outer wall and the cavity. The top end of the first mixing chamber 14 is provided with a feed inlet 18 for introducing the polymer melt into the first mixing chamber 14; a first air inlet channel 13 is arranged on the side wall of the first mixing chamber 14 and is used for introducing the first heating air into the first mixing chamber 14. It is further preferred that the first mixing chamber 14 has a height of 30-50mm, a length of 50-70mm and a width of 20-40 mm.

In the present invention, the diameter of the first air inlet channel 13 is 3-8mm, preferably 4-6mm, under the above preferred conditions, the first heating gas can be rushed into the first mixing chamber 14, the pressure of the first heating gas can be increased, and the uniformity of mixing of the first heating gas and the polymer melt can be improved.

In some preferred embodiments of the present invention, the air inlet holes 21 are arranged on the inner wall of the cavity at intervals in at least two groups along the flow direction of the first gas-liquid two-phase flow; further preferably, each air inlet hole group comprises at least two rows of air inlet hole units, and the air inlet hole units in the at least two rows are distributed on the inner wall of the cavity in a staggered manner; more preferably, the air intake hole unit includes at least four air intake holes. Under the preferable conditions, the second heating gas which passes through the second gas inlet channel 15 and enters the cavity through the gas inlet hole 21 and the first gas-liquid two-phase flow which enters the cavity from the first mixing chamber 14 can be mixed more uniformly, and the phenomenon that the polymer melt and the heating gas are layered is avoided. More specifically, the number of the air inlet holes 21 is 10-26, preferably 15-20, and may be, for example, 15, 16, 18, 20 or any integer in a range formed by any two of the above values; the diameter of the air inlet hole is 0.8-2mm, preferably 0.8-1 mm.

According to the present invention, in order to mix the second heating gas and the first gas-liquid two-phase flow more uniformly, it is preferable that the ratio of the height to the diameter of the inner cavity of the second mixing chamber 22 is 6 to 10: 1, preferably 7 to 9: 1.

in the invention, a gas channel is arranged between the outer wall 221 of the second mixing chamber and the cavity of the second mixing chamber, and the gas channel is communicated with the second gas inlet channel 15 and the gas inlet hole 21, so that the second heating gas passes through the second gas inlet channel 15 and enters the gas inlet hole 21 through the gas channel. Further, the gas channels may have a pitch of 3-8mm, for example, 3mm, 5mm, 6mm, 8mm, or any value in the range of any two of the above values.

According to the present invention, the second gas-liquid two-phase flow can be accelerated to obtain a high-speed fluid after entering the gas acceleration chamber 25. In order to increase the rotating speed of the high-speed fluid, the conicity of the conical cavity is 0.8-1.5: 1, for example, may be 0.8: 1. 1: 1. 1.2: 1. 1.5: 1 or any value in the range of any two of the above values.

According to the invention, the length to diameter ratio of the atomizing orifices 17 is between 0.5 and 5, preferably between 3.5 and 4.5: under the above preferable conditions, the pressure difference of the high-speed fluid is increased, the pulverization degree of the high-speed fluid is increased, and the particle diameter of the atomized droplets is reduced.

In the present invention, the kinds of the first, second and third heating gases may be known to those skilled in the art as long as they can heat the polymer melt without reacting with the polymer melt, and may be, for example, nitrogen or inert gas.

In a preferred embodiment of the present invention, the atomizer head comprises:

the mixing device comprises a first mixing chamber 14, wherein the first mixing chamber 14 is provided with an outer wall and a cavity (the height is 40mm, the length is 60mm, and the width is 30mm) arranged in the outer wall, two sides of the first mixing chamber 14 are respectively provided with a first air inlet channel 13 (the diameter is 5mm), the top end of the first mixing chamber 14 is provided with a feed inlet 18 (the diameter is 6-8mm), and the bottom end of the first mixing chamber 14 is provided with a liquid outlet (the diameter is 6-8 mm); the first heated air is introduced into the first mixing chamber 14 through the first intake passage 13;

the electric meshing gear can be arranged in the inner cavity of the first mixing chamber 14 in a way of rotating oppositely, the electric meshing gear is driven by an external motor, and the rotating shaft end of the motor is sealed by mechanical seal, packing seal or magnetic seal; the outer diameter of the electric meshing gear is 25mm, and the number of teeth is 24;

a liquid inlet (diameter is 1mm) of the second mixing chamber 22 is communicated with a liquid outlet of the first mixing chamber 14, the second mixing chamber 22 is provided with a second mixing chamber outer wall 221 and a cavity arranged in the outer wall (the height of the cavity is 80mm, the diameter of the cavity is 10mm), the second mixing chamber outer wall 221 is provided with a second air inlet channel 15, the inner wall of the cavity is provided with a plurality of air inlets 21, and the diameter of an air channel formed between the second mixing chamber outer wall 221 and the cavity is 5 mm; the gas channel is communicated with the second air inlet channel 15 and the air inlet hole 21; two groups of the air inlets 21 are arranged at intervals along the flowing direction of the first gas-liquid two-phase flow, and the height difference of the two adjacent groups of the air inlets is 20 mm; each air inlet hole group comprises two rows of air inlet hole units, and the two rows of air inlet hole units are distributed on the inner wall of the cavity in a staggered manner; each row of the air inlet hole units comprises four air inlet holes; the diameter of the air inlet hole is 1 mm; the second heating air enters the air inlet hole 21 through the second air inlet channel 15 through the air channel and is introduced into the cavity;

a gas acceleration chamber 25, wherein the gas acceleration chamber 25 comprises a gas acceleration chamber outer wall 251 and a conical cavity arranged in the gas acceleration chamber outer wall 251, an opening of the conical cavity is communicated with a liquid outlet of the second mixing chamber 22, and the conicity of the conical cavity is 1: 1;

an atomization nozzle 17 which is communicated with the tip of the conical cavity and is communicated with a third air inlet channel 16 arranged on the outer wall of the second mixing chamber 22, wherein the length-diameter ratio of the atomization nozzle 17 is 4, and the diameter of the nozzle is 0.8 mm; the third heating air is introduced through the third air intake passage 16.

A second aspect of the present invention provides an atomized powder system for producing a polymer powder, the atomized powder system comprising:

the feeding unit 1 is used for introducing polymer materials into the system for melting to obtain polymer melt;

the gas supply unit 6 is used for providing heating gas for the atomization powder making system;

the atomizing nozzle 2 is respectively communicated with the gas supply unit 6 and the feeding unit 1, and is used for mixing and spraying the heated gas and the polymer melt to obtain atomized liquid drops, and the atomizing nozzle 2 comprises the atomizing nozzle of the first aspect;

the cooling unit 11 is arranged below the atomizing nozzle 2 and used for cooling the atomized liquid drops to obtain polymer powder;

and a classifying and screening unit 12 arranged below the cooling unit 11 and used for screening the polymer powder to obtain polymer powder with various particle sizes.

In the invention, firstly, polymer melt is introduced into the system through a feeding unit 1, then heating gas is provided for the system through a gas supply unit 6, so that the polymer melt and the heating gas are mixed in an atomizing nozzle 2 and are ejected at high speed, and the high-speed fluid ejected at high speed is ejected from an atomizing nozzle 17 at the lower end under the collision type impact of third heating gas to form atomized liquid drops; the atomized droplets are cooled and solidified into fine polymer powder by a cooling unit 11; then, the polymer powder is screened by the classifying and screening unit 12 to obtain polymer powder with various particle sizes.

In the invention, the pressure of the polymer melt entering the atomizing nozzle is 0.3-0.8MPa, preferably 0.6 MPa; the air inlet pressure of the first heating air, the second heating air and the third heating air is respectively and independently selected from 0.3-0.8MPa, and preferably 0.6 MPa. The first, second, and third heated gases have the same temperature as the polymer melt.

According to the invention, under the preferable conditions, a heater 4 is arranged on a pipeline of the gas supply unit 6 communicated with the atomizing nozzle 2 and is used for heating the gas to obtain heated gas; further preferably, the heater 4 is respectively communicated with the first feeding channel 13, the second feeding channel 15 and the third feeding channel 16 through a pipeline 3 provided with a pressure reducing valve 9 for quantitatively introducing the heating gas into the first feeding channel 13, the second feeding channel 15 and the third feeding channel 16. More preferably, the temperature of the heating gas is 130-220 ℃. More preferably, a gas metering pump 5 is arranged on a pipeline of the gas supply unit 6 communicated with the atomizing nozzle 2 and used for controlling the total flow of the heating gas.

In some preferred embodiments of the invention, the system further comprises a control unit 8 and an analysis unit 10; the analysis unit 10 is used for analyzing the particle size and morphology of the polymer powder; the control unit 8 is electrically connected to the analysis unit 10, the heater 4 and the gas metering pump 5, and is configured to control the flow rate of the gas metering pump 5 and the temperature of the heater 4 according to the particle size and morphology of the polymer powder fed back by the analysis unit 10, so as to control the temperature and flow rate of the heated gas.

According to the invention, under the preferred conditions, a gear metering pump 7 is arranged on a pipeline for communicating the feeding unit 1 and the atomizing spray head 2 and is used for controlling the flow rate of the polymer melt; by adjusting the rotation speed of the gear metering pump 7, the amount of the polymer melt entering the atomizing nozzle 2 can be adjusted, so that the gas-liquid ratio of the heated gas and the polymer melt is adjusted.

According to the invention, under the preferable conditions, the feeding unit 1 is a screw extruder and is used for heating and melting polymer powder to obtain a polymer melt; preferably, the control unit 8 is electrically connected to the screw extruder and the gear metering pump 7, and is configured to control the temperature and pressure of the screw extruder and the rotation speed of the gear metering pump 7 according to the particle size and morphology of the polymer powder fed back by the analysis unit 10, so as to adjust the feeding amount, the extrusion temperature, and the extrusion pressure of the polymer melt.

In some preferred embodiments of the present invention, the cooling unit 11 includes a cold source and a spray head, and the cold source is sprayed on the surface of the liquid droplets through the spray head to cool the liquid droplets. The cold source is only required to cool the atomized liquid droplets, and the type of cold source is known to those skilled in the art, and may be cooling water, for example.

According to the invention, under the preferable condition, a flow regulating valve is arranged on a pipeline for communicating the cold source and the spray head. Preferably, the control unit 8 is electrically connected to the flow regulating valve, and is configured to control an opening degree of the flow regulating valve according to the particle size and morphology of the polymer powder fed back by the analysis unit 10, so as to regulate the spraying amount of the cold source.

In some preferred embodiments of the present invention, the classifying screen unit 12 includes, from top to bottom, N screens dividing the classifying screen unit 12 into N +1 screening spaces; preferably, the apertures of the N screens are gradually reduced from top to bottom. Preferably, the classifying screen unit 12 may be a vibrating classifying screen; the number and the aperture of the screens can be adjusted according to actual requirements, and the invention is not limited herein.

In a third aspect of the present invention, an atomized powder-making method for preparing polymer powder is provided, wherein polymer materials are introduced into the atomized powder-making system of the second aspect and are crushed to obtain polymer powder with various particle sizes.

In some preferred embodiments of the present invention, the atomized powdering method of preparing a polymer powder comprises:

(1) introducing polymer powder into a feeding unit 1, heating and melting the polymer powder by a screw extruder to obtain a polymer melt, and introducing the polymer melt into an atomizing nozzle 2 after quantifying the polymer melt by a gear metering pump 7;

the heating gas is divided into three paths after being heated by the heater 4, one path of the heating gas passes through the first feeding channel 13 and enters the first mixing chamber 14 (first heating gas), the other path of the heating gas enters the cavity in the second mixing chamber 22 (second heating gas) from the second feeding channel 15 through the air inlet 21, and the other path of the heating gas enters the third feeding channel 16 (third heating gas);

(2) the polymer melt enters the first mixing chamber 14 through the feeding hole 18, and under the action of the shearing assembly 19, a first heating gas enters the polymer melt to obtain a bubble-shaped first gas-liquid two-phase flow;

the bubble-shaped first gas-liquid two-phase flow flows downwards to enter a cavity in the second mixing chamber 22, is mixed with second heating gas from the gas inlet 21, and is sheared on the surface of the bubble-shaped first gas-liquid two-phase flow to generate bubbles, so that uniform bubble-shaped second gas-liquid two-phase flow is formed;

the bubble-shaped second gas-liquid two-phase flow continuously flows downwards to enter the gas acceleration chamber 25, and then is accelerated to be sprayed out of the gas acceleration chamber 25, and is sprayed out of the atomization spray hole 17 after colliding impact with third heating gas, so that atomized liquid drops are formed;

(3) the atomized droplets are rapidly cooled by the cooling unit 11 and solidified into fine polymer powder;

(4) the fine particles are sieved by a classifying and screening unit 12 to obtain polymer powder with different particle sizes.

The method of the present invention is suitable for the comminution of a wide variety of polymeric materials such as polypropylene, nylon, polyethylene, polyphenylene sulfide and the like which are well known to those skilled in the art as plastic rubbers.

The polymer powder prepared by the method has the particle size of less than 120 mu m and uniform particle size, and is particularly suitable for being used as laser-sintered 3D printing powder.

The method provided by the invention can realize uniform atomization and granulation of the high molecular polymer melt, overcomes the problem that the high molecular polymer melt has large surface tension and strong viscous force and is difficult to form uniform gas-liquid two-phase flow, can prepare powder with selectable particle size, uniform particle size distribution and high sphericity, and improves the production efficiency, the raw material powdering rate and the production continuity.

The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, numerous simple modifications can be made to the technical solution of the invention, including combinations of the individual specific technical features in any suitable way. The invention is not described in detail in order to avoid unnecessary repetition. Such simple modifications and combinations should be considered within the scope of the present disclosure as well.