Double-layer scattering powder concentrator based on numerical simulation and design method thereof

Abstract

The invention discloses a numerical simulation-based double-layer scattering powder concentrator and a design method thereof, and particularly relates to the technical field of cement grinding, the numerical simulation-based double-layer scattering powder concentrator comprises a shell and a rotating cage, and an annular inner ring impact plate and an annular outer ring impact plate are arranged at the top of the shell; the top of the rotating cage is provided with a circular-ring-shaped upper material scattering disc and a circular-ring-shaped lower material scattering disc, the upper material scattering disc is located above the lower material scattering disc, and the upper material scattering disc and the lower material scattering disc are arranged to be of a tooth type structure along the circumference; the rotating cage rotates in the shell in a limited mode. Through cooperation of the inner ring counterattack plate and the upper scattering disc, one-time scattering of materials is completed; according to the double-layer scattering powder concentrator, secondary scattering of materials is completed through cooperation of the outer ring impact plate and the lower scattering disc, so that even distribution of the materials in the circumferential direction is guaranteed under the condition that the number of feeding ports is small, secondary scattering of the materials can be achieved, and therefore the sorting efficiency and sorting precision of the double-layer scattering powder concentrator are effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of cement grinding, and more specifically to a double-layer material spreading powder classifier based on numerical simulation and a design method thereof. Background Art

[0002] It is known that in cement production, the closed-circuit grinding system can not only increase the output of the mill, but also reduce the power consumption of cement and the temperature of the finished product compared with the open-circuit grinding system, thereby making it easy and convenient to control the fineness, and the finished product particles are more uniform, and the energy consumption of the mill is reduced; among them, the post-grinding powder classifier is a key equipment in the system, which is mainly responsible for the screening of the particle size of the particles entering the mill and the finished product.

[0003] At present, most of the powder classifiers used after grinding are O-Sepa powder classifiers or improved types based on O-Sepa powder classifiers. The main classification structures of the two are basically the same; the core component of the O-Sepa powder classifier is a cage rotor with partitions on the rotor, and blades are welded between the partitions and evenly distributed along the circumference; a sealing ring and a spreading plate are provided on the upper part of the rotor; and then the material is fed from the feeding port, hit and dispersed on the spreading plate, and then flies in the circumferential direction, and then collides with the impact plate and enters the powder selection area. The particles dispersed by the airflow in the powder selection area are adjusted by the guide vanes and the rotor for vortex adjustment, and the classification is achieved under the action of centrifugal force and inward airflow drag: 1. The classified fine powder is sent to the center of the powder selection chamber together with the classified air (air or dust-containing air) sent from the first and second air inlets, and then enters the air outlet pipe; Second, the coarse powder classified by centrifugal action is led to the outer guide vanes and flows along the inner side of the guide vanes. The fine powder on the surface of the coarse powder is washed by the air flowing in from the primary and secondary air ports to achieve secondary classification of the coarse powder; 3. The coarse powder collected in the lower ash hopper will be washed again by the tertiary air flow in the process of falling into the lower ash hopper, and some of the entrained fine powder will be brought into the sorting area for sorting; It can be seen that the O-Sepa powder classifier has advanced principles and clear classification mechanisms, and has obvious advantages over traditional centrifugal and cyclone powder classifiers; It can be seen that the O-Sepa powder classifier has advanced principles and clear classification mechanism, and has obvious advantages over traditional centrifugal and cyclone powder classifiers.

[0004] However, in actual use, the existing material spreading structure design has certain shortcomings. For example, due to the arrangement of the outlet air duct and the drive device, the number of feeding ports of the O-Sepa powder classifier is limited. Usually, only four feeding ports are arranged, and the distribution is uneven. Through on-site observation and simulation results, it can be found that even if the four feeding ports are evenly distributed, it is difficult to achieve uniform distribution of materials along the circumferential direction. As a result, the material cannot form a uniform material curtain in the annular sorting area: that is, the material layer in the area near the discharge port is too thick, and the airflow is difficult to penetrate; and the material layer far away from the discharge port is too thin, and the airflow is easy to form a short circuit, which limits the further improvement of the sorting efficiency and sorting accuracy of the O-Sepa powder classifier to a certain extent. Therefore, the present invention proposes a double-layer material spreading powder selecting machine based on numerical simulation and a design method thereof as a further improvement. Summary of the invention

[0005] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides a double-layer material spreading powder classifier based on numerical simulation and a design method thereof to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a double-layer material-spreading powder-selecting machine, the double-layer material-spreading powder-selecting machine comprising: a shell and a rotating cage, A circular inner ring impact plate and a circular outer ring impact plate are arranged on the top of the shell; a circular upper material scattering plate and a circular lower material scattering plate are arranged on the top of the rotating cage, and the upper material scattering plate is located above the lower material scattering plate, and the upper material scattering plate and the lower material scattering plate are both arranged in a toothed structure along the circumference; the rotating cage rotates within a limited position inside the shell, and a feeding pipe located above the upper material scattering plate is arranged on the top of the shell.

[0007] Further, the bottom of the outer ring impact plate is fixedly mounted at the circular opening at the top of the shell, a circular connecting plate is arranged at the top of the outer ring impact plate, the top of the outer ring impact plate is fixedly connected to the outer ring of the connecting plate, the top of the inner ring impact plate is fixedly mounted on the lower surface of the connecting plate, a plurality of evenly distributed feeding ports are opened on the connecting plate, and the feeding pipe is fixedly mounted at the feeding port; A plurality of guide blades are fixedly mounted on the inner wall of the shell, and the guide blades are evenly distributed on the periphery of the rotating cage in a circumferential manner.

[0008] Furthermore, the rotating cage further comprises: a rotating body and an annular plate, The top of the rotating body is fixedly connected to the bottom of the annular plate through a plurality of evenly distributed support rods, and the inner rings of the upper material spreading plate and the lower material spreading plate are fixedly connected to the side wall of the annular plate; The outer ring edge of the lower material spreading plate is fixedly connected to the edge of the bottom of the rotating body through a plurality of evenly distributed rotating cage blades.

[0009] Furthermore, the upper material spreading plate of the toothed structure comprises: a primary baffle and an upper annular material spreading plate, The inner ring of the upper annular material spreading plate is fixedly connected to the side wall of the annular plate, and the outer ring of the upper annular material spreading plate is fixedly connected to the bottom of the primary baffle; The primary baffle is provided with a plurality of first tooth-shaped notches evenly distributed along the circumference.

[0010] Furthermore, the lower material spreading plate of the toothed structure comprises: a secondary baffle and a lower annular material spreading plate, The inner ring of the lower annular material spreading plate located below the upper annular material spreading plate is fixedly connected to the side wall of the annular plate, and the outer ring of the lower annular material spreading plate is fixedly connected to the bottom of the secondary baffle; The secondary baffle is provided with a plurality of second tooth-shaped notches evenly distributed along the circumference; the upper surface of the lower annular material spreading plate is fixedly mounted with a plurality of spacer plates evenly distributed along the circumference, and the two ends of the spacer plates are respectively fixedly connected to the secondary baffle and the lower annular material spreading plate.

[0011] Further, the maximum diameter of the upper annular material spreading disc is smaller than the diameter of the inner ring impact plate, the diameter of the inner ring impact plate is smaller than the maximum diameter of the lower annular material spreading disc, and the maximum diameter of the lower annular material spreading disc is smaller than the diameter of the outer ring impact plate; The height of the lowest surface of the inner ring impact plate is not higher than the height of the lowest surface of the upper annular material spreading plate.

[0012] A design method of a double-layer material-spreading powder-selecting machine based on numerical simulation, including the double-layer material-spreading powder-selecting machine, comprises the following steps: S1: Establishing a geometric model of the double-layer material spreading powder selection machine by using a three-dimensional modeling software; S2: Then, a simulation model of the double-layer material spreading powder selection machine is established by discrete element software; S3: The regression model of the tooth profile notch envelope angle and the number of tooth profile notches of the first tooth profile notch and the second tooth profile notch on the response variable is calculated by the simulation model and experimental design method of the double-layer material spreading powder classifier; the response variable is the variance value of the material amount in each area of ​​the separation zone of the double-layer material spreading powder classifier; S4: Determine whether the main parameters of the rotating cage: rotation speed, radius, height have changed significantly: if there is a significant change, the tooth profile notch envelope angle and the number of tooth profile notches need to be readjusted, and then return to S1; if not, enter S5; S5: Determine the tooth profile notch envelope angle and the number of tooth profile notches of the first tooth profile notch and the second tooth profile notch.

[0013] Furthermore, in S3, the experimental design method includes: S31: Determine the experimental design factors; and divide each factor into 3 levels; S32: construct experimental combination matrix; S33: Conduct experiments according to the experimental combination matrix: S34: record the response value variable of each experiment; S35: Perform data analysis, including regression analysis, analysis of variance, and model diagnosis.

[0014] Technical effects and advantages of the present invention: 1. Compared with the prior art, the inner ring impact plate is arranged in cooperation with the upper spreading plate to complete the primary dispersion of the material; the outer ring impact plate is used in cooperation with the lower spreading plate to complete the secondary dispersion of the material, so that when the number of feeding ports is small, it has a better delayed dispersion effect, ensures the uniform distribution of the material along the circumferential direction, and can also disperse the material for the second time, thereby effectively improving the sorting efficiency and sorting accuracy of the double-layer spreading powder classifier.

[0015] 2. Compared with the prior art, the present invention provides a design method for a double-layer material spreading powder classifier based on numerical simulation. The setting of the tooth notch envelope angle and the number of tooth notches of the first tooth notch and the second tooth notch is more reasonable, and simulation verification is used to ensure that no material blockage will occur. This improves the actual material distribution effect of the double-layer material spreading powder classifier, and can avoid material blockage, which is beneficial to the efficient and reliable operation of the double-layer material spreading powder classifier. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0017] Figure 2 It is a top view of the overall structure of the present invention.

[0018] Figure 3 It is a three-dimensional schematic diagram of the cross-sectional structure of the present invention.

[0019] Figure 4 It is a plan view schematically showing the cross-sectional structure of the present invention.

[0020] Figure 5 It is a schematic diagram of the planar structure of the rotating cage of the present invention.

[0021] Figure 6 It is a schematic diagram of the three-dimensional structure of the rotating cage of the present invention.

[0022] The accompanying drawings are marked as follows: 1. Shell; 11. Inner ring impact plate; 12. Outer ring impact plate; 13. Connecting plate; 131. Feeding port; 2. Rotating cage; 21. Upper spreading plate; 211, primary baffle; 212, upper annular material spreading plate; 213, first tooth-shaped notch; 22. Lower spreading plate; 221, secondary baffle; 222, lower annular material spreading plate; 223, second tooth-shaped notch; 224, spacer plate; 23. Rotating body; 24. Ring-shaped plate; 3. Feeding pipe; 4. Guide blades; 5. Rotating cage blades. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0024] As attached Figure 1-6 The double-layer material-spreading powder-selecting machine shown in the figure comprises: a housing 1 and a rotating cage 2. A circular inner ring impact plate 11 and a circular outer ring impact plate 12 are arranged on the top of the shell 1; a circular upper material scattering plate 21 and a circular lower material scattering plate 22 are arranged on the top of the rotating cage 2, and the upper material scattering plate 21 is located above the lower material scattering plate 22, and the upper material scattering plate 21 and the lower material scattering plate 22 are both arranged in a toothed structure along the circumference; the rotating cage 2 rotates within the shell 1, and a feeding pipe 3 located above the upper material scattering plate 21 is arranged on the top of the shell 1.

[0025] The double-layer material-spreading powder-selecting machine further includes a driving mechanism and a lubrication system for driving the rotating cage 2 to rotate; Among them, the upper material spreading plate 21 and the lower material spreading plate 22 rotate synchronously with the rotating cage 2; The inner ring impact plate 11 and the outer ring impact plate 12 fixed on the shell cooperate with the upper material spreading plate 21 and the lower material spreading plate 22 to jointly complete the dispersion and uniform distribution of the materials.

[0026] Among them, an upper material spreading plate 21 and a lower material spreading plate 22 are arranged on the top of the rotating cage 2, and a tooth structure is arranged along the circumference to realize the delayed spreading of the material falling from the feeding pipe 3; In a preferred embodiment, as shown in the attached Figure 1-6As shown, the bottom of the outer ring impact plate 12 is fixedly mounted at the circular opening at the top of the housing 1, a circular connecting plate 13 is arranged at the top of the outer ring impact plate 12, the top of the outer ring impact plate 12 is fixedly connected to the outer ring of the connecting plate 13, the top of the inner ring impact plate 11 is fixedly mounted on the lower surface of the connecting plate 13, a plurality of evenly distributed feeding ports 131 are opened on the connecting plate 13, and the feeding pipe 3 is fixedly mounted at the feeding port 131; A plurality of guide blades 4 are fixedly mounted on the inner wall of the housing 1 , and the guide blades 4 are evenly distributed around the periphery of the rotating cage 2 in a circumferential manner.

[0027] In a preferred embodiment, as shown in the attached Figure 1-6 As shown, the rotating cage 2 also includes a rotating body 23 and an annular plate 24. The top of the rotating body 23 is fixedly connected to the bottom of the annular plate 24 through a plurality of evenly distributed support rods, and the inner rings of the upper material spreading plate 21 and the lower material spreading plate 22 are fixedly connected to the side wall of the annular plate 24; The outer edge of the lower spreading plate 22 is fixedly connected to the edge of the bottom of the rotating body 23 through a plurality of evenly distributed cage blades 5 .

[0028] In a preferred embodiment, as shown in the attached Figure 1-6 As shown, the upper spreading plate 21 of the toothed structure includes: a primary baffle 211 and an upper annular spreading plate 212. The inner ring of the upper annular material spreading plate 212 is fixedly connected to the side wall of the annular plate 24, and the outer ring of the upper annular material spreading plate 212 is fixedly connected to the bottom of the primary baffle 211; The primary baffle 211 is provided with a plurality of first tooth-shaped notches 213 evenly distributed along the circumference.

[0029] In a preferred embodiment, as shown in the attached Figure 1-6 As shown, the lower spreading plate 22 of the toothed structure includes: a secondary baffle 221 and a lower annular spreading plate 222. The inner ring of the lower annular material spreading plate 222 located below the upper annular material spreading plate 212 is fixedly connected to the side wall of the annular plate 24, and the outer ring of the lower annular material spreading plate 222 is fixedly connected to the bottom of the secondary baffle 221; The secondary baffle 221 is provided with a plurality of second tooth-shaped notches 223 evenly distributed along the circumference; the upper surface of the lower annular material spreading plate 222 is fixedly mounted with a plurality of spacer plates 224 evenly distributed along the circumference, and the two ends of the spacer plates 224 are respectively fixedly connected to the secondary baffle 221 and the lower annular material spreading plate 222.

[0030] In a preferred embodiment, as shown in the attached Figure 1-6As shown, the maximum diameter of the upper annular material spreading disc 212 is smaller than the diameter of the inner ring impact plate 11, the diameter of the inner ring impact plate 11 is smaller than the maximum diameter of the lower annular material spreading disc 222, and the maximum diameter of the lower annular material spreading disc 222 is smaller than the diameter of the outer ring impact plate 12; The height of the lowest surface of the inner ring impact plate 11 is not higher than the height of the lowest surface of the upper annular material spreading plate 212 .

[0031] Working principle of the present invention: The material falls from the feeding port 131 through the feeding pipe 3 into the upper scattering plate 21. The rotation of the rotating body 23 drives the upper scattering plate 21 to rotate, and then the material on the upper scattering plate 21 moves to the edge of the upper scattering plate 21 under the action of centrifugation. After being blocked by the primary baffle 211, part of the material is thrown onto the inner ring impact plate 11 through the first tooth-shaped notch 213, and the other part continues to rotate and is thrown onto the inner ring impact plate 11 through the next first tooth-shaped notch 213; thus, the material thrown onto the inner ring impact plate 11 is completely broken up and falls into the lower scattering plate 22; The material falling into the lower spreading plate 22 moves toward the edge of the lower spreading plate 22 under the action of centrifugation, is blocked by the secondary baffle 221, and is thrown onto the outer ring impact plate 12, where it is broken up again and finally falls into the sorting area of ​​the rotating body 23.

[0032] The design of the inner ring impact plate 11 needs to cooperate with the upper scattering plate 21 to complete the primary dispersion of the material, while the design of the outer ring impact plate 12 needs to cooperate with the lower scattering plate 22 to complete the secondary dispersion of the material.

[0033] As attached Figure 1-6 As shown, a design method of a double-layer material-spreading powder-selecting machine based on numerical simulation includes a double-layer material-spreading powder-selecting machine, including the following steps: S1: Establish the geometric model of the double-layer material spreading and powder selection machine through 3D modeling software; S2: Then, a simulation model of the double-layer material spreading and powder selection machine is established through discrete element software; Among them, the simulation model can obtain the uniformity data of the double-layer material spreading and powder selection machine; S3: The regression model of the tooth gap envelope angle and the number of tooth gaps of the first tooth gap 213 and the second tooth gap 223 with respect to the response variable is calculated by using the simulation model of the double-layer material-spreading powder classifier and the Box-Behnken experimental design method; the response variable is the variance value of the material amount in each area of ​​the separation zone of the double-layer material-spreading powder classifier; S4: Determine whether the main parameters of the rotating cage 2: rotation speed, radius, height have changed significantly: if there is a significant change, the tooth profile notch envelope angle and the number of tooth profile notches need to be readjusted, and then return to S1; if not, enter S5; S5: Determine the tooth-shaped notch envelope angles and the number of tooth-shaped notches of the first tooth-shaped notch 213 and the second tooth-shaped notch 223 .

[0034] Among them, considering that the tooth-shaped gap envelope angle and the number of tooth-shaped gaps of the first tooth-shaped gap 213 and the second tooth-shaped gap 223 are set unreasonably, it is not only easy to cause the actual material distribution effect of the double-layer material-spreading powder selection machine to be poor, but even cause material blockage in serious cases, which is not conducive to the efficient and reliable operation of the double-layer material-spreading powder selection machine; therefore, the tooth-shaped gap envelope angle and the number of tooth-shaped gaps of the first tooth-shaped gap 213 and the second tooth-shaped gap 223 are determined by establishing a simulation model and an experimental design method; In a preferred embodiment, as shown in the attached Figure 1-6 As shown in S3, the Box-Behnken experimental design method includes: S31: Determine the experimental design factors; and divide each factor into 3 levels; S32: construct experimental combination matrix; S33: Conduct experiments according to the experimental combination matrix: S34: record the response value variable of each experiment; S35: Perform data analysis, including regression analysis, analysis of variance, and model diagnosis.

[0035] Embodiment: The experimental design factors are set as: the tooth profile notch envelope angle A of the first tooth profile notch 213, the number of tooth profile notches B, the tooth profile notch envelope angle C of the second tooth profile notch 223, the number of tooth profile notches D; each factor is set to 3 levels, the low level is -1, the medium level is 0, and the high level is 1;

[0036] The above table shows the constructed experimental matrix. A total of 19 groups of experiments were conducted, including 1 group of center point experiments.

[0037] According to the experimental combination to be carried out, the simulation calculation of the corresponding parameter combination is carried out in the simulation model in turn, and the variance value S of the material quantity in each area under each experimental parameter condition is recorded respectively, and finally 19 groups of data are obtained:

[0038] Subsequently, statistical software was used for data analysis; regression analysis was performed: a polynomial regression model of the variance value S of each stock volume with respect to the tooth profile gap envelope angle and the number of tooth profile gaps of the first tooth profile gap 213 and the second tooth profile gap 223 was constructed; then, the goodness of fit of the model (such as the R² value) was evaluated. After a relatively reliable polynomial regression model of the variance value S of the material volume in each region was obtained by cross-validating the accuracy of the model using different data sets, a relatively reasonable tooth profile gap envelope angle and the number of tooth profile gaps were obtained through the planning solver to ensure that the variance value S of each stock volume was at a low level, and a simulation verification was performed to ensure that no material blockage would occur.

[0039] Among them, when the main parameters of the rotating cage 2 are the rotating speed, radius and height, if there are large changes, the tooth profile notch envelope angle and the number of tooth profile notches need to be readjusted; and then the tooth profile notch envelope angle and the number of tooth profile notches are finally determined; Therefore, the coordination of the upper spreading plate 21, the lower spreading plate 22, the inner ring impact plate 11 and the outer ring impact plate 12 can realize the delayed spreading and secondary breaking of the material, which is beneficial to the improvement of the sorting efficiency and sorting accuracy of the powder classifier.

[0040] Specifically, the present invention focuses on optimizing the uniformity of material spreading of the powder classifier, aiming to improve the sorting performance of the double-layer material spreading powder classifier and the economy of the air separation system.

[0041] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0042] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A double-layer powder-spreading machine, characterized in that: The double-layer material-spreading powder-selecting machine comprises: a housing (1) and a rotating cage (2). The top of the shell (1) is provided with an annular inner ring impact plate (11) and an annular outer ring impact plate (12); the top of the rotating cage (2) is provided with an annular upper material scattering plate (21) and an annular lower material scattering plate (22), and the upper material scattering plate (21) is located above the lower material scattering plate (22), and the upper material scattering plate (21) and the lower material scattering plate (22) are both arranged along the circumference to form a toothed structure; the rotating cage (2) is limitedly rotated inside the shell (1), and the top of the shell (1) is provided with a feeding pipe (3) located above the upper material scattering plate (21).

2. A double-layer powder-spreading and selecting machine according to claim 1, characterized in that: The bottom of the outer ring impact plate (12) is fixedly mounted at the circular opening at the top of the housing (1); a circular connecting plate (13) is provided at the top of the outer ring impact plate (12); the top of the outer ring impact plate (12) is fixedly connected to the outer ring of the connecting plate (13); the top of the inner ring impact plate (11) is fixedly mounted on the lower surface of the connecting plate (13); a plurality of evenly distributed feeding ports (131) are provided on the connecting plate (13); and the feeding pipe (3) is fixedly mounted at the feeding port (131); A plurality of guide blades (4) are fixedly mounted on the inner wall of the shell (1), and the plurality of guide blades (4) are evenly distributed in a circular pattern on the periphery of the rotating cage (2).

3. A double-layer powder-spreading and selecting machine according to claim 1, characterized in that: The rotating cage (2) further comprises: a rotating body (23) and an annular plate (24). The top of the rotating body (23) is fixedly connected to the bottom of the annular plate (24) via a plurality of evenly distributed support rods, and the inner rings of the upper material spreading plate (21) and the lower material spreading plate (22) are fixedly connected to the side wall of the annular plate (24); The outer edge of the lower spreading plate (22) is fixedly connected to the edge of the bottom of the rotating body (23) via a plurality of evenly distributed cage blades (5).

4. A double-layer powder-spreading and selecting machine according to claim 3, characterized in that: The upper material spreading plate (21) of the toothed structure comprises: a primary baffle (211) and an upper annular material spreading plate (212). The inner ring of the upper annular material spreading plate (212) is fixedly connected to the side wall of the annular plate (24), and the outer ring of the upper annular material spreading plate (212) is fixedly connected to the bottom of the primary baffle (211); The primary baffle (211) is provided with a plurality of first tooth-shaped notches (213) evenly distributed along the circumference.

5. A double-layer powder-spreading and selecting machine according to claim 4, characterized in that: The lower material spreading plate (22) of the toothed structure comprises: a secondary baffle (221) and a lower annular material spreading plate (222). The inner ring of the lower annular material spreading plate (222) located below the upper annular material spreading plate (212) is fixedly connected to the side wall of the annular plate (24), and the outer ring of the lower annular material spreading plate (222) is fixedly connected to the bottom of the secondary baffle (221); The secondary baffle plate (221) is provided with a plurality of second tooth-shaped notches (223) evenly distributed along the circumference; the upper surface of the lower annular material spreading plate (222) is fixedly mounted with a plurality of spacer plates (224) evenly distributed along the circumference, and the two ends of the spacer plates (224) are respectively fixedly connected to the secondary baffle plate (221) and the lower annular material spreading plate (222).

6. A double-layer powder-spreading and selecting machine according to claim 5, characterized in that: The maximum diameter of the upper annular material spreading disc (212) is smaller than the diameter of the inner ring impact plate (11), the diameter of the inner ring impact plate (11) is smaller than the maximum diameter of the lower annular material spreading disc (222), and the maximum diameter of the lower annular material spreading disc (222) is smaller than the diameter of the outer ring impact plate (12); The height of the lowest surface of the inner ring impact plate (11) is not higher than the height of the lowest surface of the upper annular material spreading plate (212).

7. A design method for a double-layer material-spreading powder-selecting machine based on numerical simulation, comprising a double-layer material-spreading powder-selecting machine according to any one of claims 1 to 6, characterized in that: The steps include: S1: Establishing a geometric model of the double-layer material spreading powder selection machine by using a three-dimensional modeling software; S2: Then, a simulation model of the double-layer material spreading powder selection machine is established by discrete element software; S3: Calculating the regression model of the tooth-shaped notch envelope angle and the number of tooth-shaped notches of the first tooth-shaped notch (213) and the second tooth-shaped notch (223) with respect to the response variable through the simulation model and experimental design method of the double-layer material-spreading powder classifier; the response variable is the variance value of the material amount in each area of ​​the separation zone of the double-layer material-spreading powder classifier; S4: Determine whether the main parameters of the rotating cage (2): rotation speed, radius, height have changed significantly: if there is a significant change, the tooth profile notch envelope angle and the number of tooth profile notches need to be readjusted, and then return to S1; if not, enter S5; S5: Determine the tooth profile notch envelope angle and the number of tooth profile notches of the first tooth profile notch (213) and the second tooth profile notch (223).

8. The design method of a double-layer material-spreading powder-selecting machine based on numerical simulation according to claim 7 is characterized in that: In S3, the experimental design method includes: S31: Determine the experimental design factors; and divide each factor into 3 levels; S32: construct experimental combination matrix; S33: Conduct experiments according to the experimental combination matrix: S34: record the response value variable of each experiment; S35: Perform data analysis, including regression analysis, analysis of variance, and model diagnosis.

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