Multi-layer screen vibrating screen capable of being used for screening fine particles

Abstract

The invention discloses a multi-layer screen vibrating screen capable of being used for fine particle screening. The multi-layer screen vibrating screen comprises a base, an inclined outer screen frame, at least three layers of filter screens, a vibrating motor, an interlayer supporting and tensioning mechanism, an ultrasonic screen cleaning device and a discharging system. Through multi-layer fine grading, weak vibration breaking prevention, high-frequency net cleaning and dynamic parameter adjustment, the problems that traditional screening precision is low, hole blocking and breaking are prone to occurring, the yield is insufficient, and red and white rapeseed skin impurities are difficult to clean are solved, the impurity cleaning precision is larger than 95%, the rapeseed impurities are smaller than 1%, the device is matched with a hydraulic turning plate, and the screening quality and efficiency are guaranteed.

Description

Technical Field

[0001] This invention relates to the field of screening equipment technology, and in particular to a multi-layer vibrating screen that can be used for screening fine particles. Background Technology

[0002] In the grain and oil processing sector, the cleaning and screening of grains (rice, wheat, corn) and oilseeds (especially rapeseed) is a core process for ensuring raw material quality and processing efficiency. However, existing technologies face significant bottlenecks, particularly when dealing with multi-level impurity separation, high-yield requirements, and special materials like rapeseed: 1. Insufficient number of traditional screening layers limits output and grading efficiency: Existing vibrating screens are mostly 2-3 layer structures, capable of only basic cleaning of large and medium impurities, unable to achieve multi-level fine separation such as "small impurities - broken grains - clean grains" and "rough grains - broken rice - whole grains". For example, when the impurity content of raw grains is 3%, traditional equipment can only clean 30 tons / hour of rice, 80 tons / hour of wheat, and 90 tons / hour of corn, requiring multiple screenings to complete grading, resulting in low efficiency. While increasing the number of screen layers can increase output (user verification shows "adding one layer increases output by 30%)", traditional structures suffer from insufficient support rigidity, easy loosening of screen tension, and resonance shift after multiple layers are stacked, leading to decreased screening accuracy and making it difficult to stably achieve efficient screening with 4 or more layers. 2. Incomplete removal of impurities, especially the problem of "red and white inner skin" in rapeseed: Rapeseed grains are small (about 1.5-2.5mm in diameter) and light (about 2-4g per thousand grains). The red / white seed coat (commonly known as "inner skin") attached to their surface is thin and easily floats. Traditional screens (woven mesh or ordinary square mesh) are difficult to intercept such light impurities due to their large pore size (usually ≥3mm) and poor vibration parameter adaptability. At the same time, rapeseed has a high oil content (about 35-45%), and impurities adhere strongly to the grains, easily clogging the screen holes. The traditional bouncing ball cleaning efficiency is less than 50%, resulting in rapeseed still containing a large amount of red and white skin impurities (up to 5-8%) after cleaning, which seriously affects the oil yield and color of the oil. 3. Poor compatibility with subsequent processes and low efficiency of process connection: Scenarios such as grain depots require the use of equipment such as hydraulic tippers, which require the screening equipment to have the ability of "rapid discharge and continuous feeding". However, the discharge port design of traditional screening equipment is simple (only the bottom discharges the total material), which cannot collect different grades of materials in layers. Moreover, the flow rate matching with hydraulic tippers is poor (e.g., if 50 tons of rice are required to be cleaned in 1 hour), the process is often interrupted due to poor discharge. 4. Core performance defects: Easily broken, easily clogged, and fixed parameters: Particle crushing: To increase output, traditional equipment often adopts strong vibration mode (amplitude > 5mm, frequency > 1500rpm), which leads to the breakage of grains (such as rice grains and corn germ) and rapeseed shells, resulting in a reduced yield (rapeseed breakage rate is often > 3%); Easily clogged screens: Fine particles (such as rapeseed dust and grain fragments) easily adhere to the screen holes. Traditional screen cleaning methods (bouncing balls, rubber balls) have insufficient impact force, requiring frequent shutdowns for cleaning (every 2-3 hours), affecting continuous production; Fixed parameters: The vibration direction (motor shaft angle), frequency, and amplitude are fixed, making it impossible to adapt to different material characteristics (such as poor rice flowability and light and easily splashing rapeseed), easily resulting in screening dead zones or excessive vibration.

[0003] In summary, existing technologies cannot meet the comprehensive requirements of "multi-layer fine grading, high yield and efficiency, thorough cleaning of rapeseed red and white skin impurities, and compatibility with hydraulic flippers". Especially in the field of rapeseed cleaning, "small particles, light impurities, easy clogging of holes, and difficulty in separation" are global problems that urgently require breakthrough technical solutions. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a multi-layer vibrating screen that can be used for fine particle screening.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: The present invention provides a multi-layer vibrating screen for fine particle screening, comprising: a base on which a shock absorber and adjustable anchor bolts are provided; An outer screen frame is inclinedly mounted on the base and connected to the base via a shock absorber. It has at least three layers of filter screens inside, with the layers separated by interlayer supports and tensioning mechanisms. The inner side of the outer screen frame is provided with a sealing strip, the top feed end is provided with an L-shaped stainless steel baffle, and the bottom is provided with a side wall support. A vibrating motor is installed on the outside of the outer screen frame, and the angle between its axis and the horizontal plane can be steplessly adjusted from 0° to 45° through an adjusting seat. An interlayer support and tensioning mechanism is provided inside the outer screen frame, including parallel support beams, mesh supports and tensioning bolts; the support beams extend along the length of the outer screen frame, dividing the inner cavity of the outer screen frame into at least three layers of screen installation space; A screen cleaning device is integrated below each layer of the filter screen; The discharge system includes a waste discharge outlet located on the side wall of each layer of filter screen of the outer screen frame, and a discharge port located at the bottom of the outer screen frame; The filter screen is a small-aperture woven mesh or a stainless steel elastic square mesh, with the aperture decreasing from top to bottom in each layer; the vibrating motor operates in a weak vibration mode, and its amplitude, frequency, eccentric block angle, and axis angle with the horizontal plane are adapted to the fine particle anti-breakage screening requirements.

[0006] As a preferred embodiment of the present invention, the bottom of the outer screen frame is bolted to the side wall support of the base via an adjusting screw and the shock absorber; the shock absorber is a helical steel spring shock absorber, and its top end is connected to the side wall support.

[0007] As a preferred embodiment of the present invention, the length of the support beam of the interlayer support and tensioning mechanism matches the inner width of the outer screen frame, and both ends are fixedly connected to the two sides of the outer screen frame by bolts; the spacing between adjacent support beams is 20-25mm, and the support beam is provided with an installation groove, the width of which matches the thickness of the mesh support.

[0008] As a preferred embodiment of the present invention, the mesh support of the interlayer support and tensioning mechanism is a stainless steel perforated plate, which is embedded in the mounting groove of the support beam; the edge of the filter screen is embedded in the U-shaped groove of the mesh support and fixed by the tensioning bolts at the four corners of the mesh support, and the tensioning bolts pass through the through holes in the side wall of the outer screen frame and are screwed to the mesh support.

[0009] As a preferred embodiment of the present invention, the vibration motor is a vertical explosion-proof motor, which is symmetrically installed on the middle of the circular support base on the outer side of the outer screen frame via the adjusting seat; the circular support base is provided with an angle scale, and the adjusting seat has an arc-shaped mounting interface and a central motor mounting hole, so as to realize stepless adjustment of the angle between the axis of the vibration motor and the horizontal plane, and is fixed by a double locking mechanism after adjustment; preferably, there are two vibration motors, which are symmetrically arranged.

[0010] As a preferred embodiment of the present invention, the cleaning device is ultrasonically driven and includes a piezoelectric ceramic sheet, an electrode sheet, and a protective cover integrated under each layer of the filter screen. The piezoelectric ceramic sheet is a circular sheet that is attached to the back of the filter screen and removes fine particulate impurities through high-frequency micro-vibration. The electrode sheet is a copper foil that covers the outside of the piezoelectric ceramic sheet and is connected to a high-frequency generator through a wire. The protective cover is a stainless steel mesh cover that covers the piezoelectric ceramic sheet and is bolted to the support beam, located 5-10 mm away from the back of the filter screen.

[0011] As a preferred embodiment of the present invention, a set of ultrasonic cleaning components is provided below each layer of the filter screen. Each set of components includes the piezoelectric ceramic sheet, electrode sheet and protective cover. Each set of components is connected to the control box through wires and can be independently controlled to start and stop. The high frequency generator outputs 50-100W.

[0012] As a preferred embodiment of the present invention, the discharge outlet of the discharge system is a side wall slag discharge port, which is a rectangular hole opened in the corresponding side wall of each layer of filter screen of the outer screen frame; the discharge outlet is provided with a flip-up baffle, which is rotatably connected to the outer screen frame by hinges on both sides, and an elbow switch is provided on one side; each layer of filter screen is provided with a branch discharge port at the bottom, and the discharge ports converge to the main discharge port; the discharge port includes a discharge trough inclinedly arranged at the bottom of the outer screen frame.

[0013] As a preferred embodiment of the present invention, the filter screen is a stainless steel elastic square hole mesh with a square hole size of 4×4mm, a hole spacing of 5mm, and a thickness of 5mm; in the weak vibration mode of the vibration motor, the amplitude is 2-3mm, the frequency is 800-1200rpm, the eccentric block angle is 0°-90°, the excitation force of each motor is 2-5kN, and the angle between the axis and the horizontal plane is 10°-15°.

[0014] As a preferred embodiment of the present invention, the base is a grid-shaped steel structure, with the spiral steel spring shock absorbers and adjustable anchor bolts at the four corners.

[0015] This patent addresses the six-layer structure design for grain and oil screening. Through four core innovations—multi-layer fine grading, dynamic parameter adaptation, efficient screen cleaning and anti-clogging, and specialized impurity separation—it systematically solves the aforementioned technical problems, achieving "high-yield, high-precision, and high-adaptability" screening. In particular, it overcomes the global challenge of cleaning rapeseed. Compared with existing technologies, the beneficial effects of this invention are as follows: 1. Clearly defined functional layers covering all impurity types: Building upon the original three layers, a 30% increase in raw grain cleaning output is achieved through a decreasing aperture design. The fourth layer utilizes a high-efficiency square-hole screen, combining negative pressure adsorption of light impurities with vibration-enhanced stratification and material waterfall dispersion technology to peel off adhering impurities using the impact force of the waterfall. The fifth layer is specifically designed for use with the hydraulic tilting system in grain depots, optimizing the discharge chute angle and the layout of the branch discharge outlets to achieve 50 tons of rice cleaning per hour, seamlessly matching the flow rate of the hydraulic tilting system to avoid process interruptions. The sixth layer features an innovative design for rapeseed, using an ultra-small aperture square-hole screen to intercept red and white inner skin impurities. Combined with weak vibration and anti-splash parameters, it achieves three-stage separation of rapeseed: "whole grains - damaged grains - red and white skin impurities," resulting in an impurity content of <1% after cleaning (compared to >5% in traditional equipment). 2. Specialized Screen and Cleaning Design: The sixth layer uses a stainless steel elastic square-hole mesh, which not only intercepts red and white skin impurities but also prevents rapeseed from passing through the screen; an integrated ultrasonic cleaning device is used, with piezoelectric ceramic plates attached to the back of the screen, which peels off the adhering red and white skin through high-frequency vibration, requiring no cleaning after 8 hours of continuous operation; weak vibration to prevent breakage and splashing: The vibration motor operates in a weak vibration mode, with a motor axis tilt angle of 10°-15°, so that the rapeseed is in a state of "gentle slope sliding + slight jumping", avoiding high-speed impact breakage; at the same time, a guide plate is added to the discharge port to prevent the loss of light rapeseed by splashing; the sixth layer has an independent impurity discharge outlet on its side wall, and the red and white skin impurities are collected through the branch impurity discharge outlets to the main impurity discharge outlet, with a collection rate of over 98%, completely solving the problem of "large amount of red and white skin and difficulty in cleaning", and increasing the oil extraction yield by 3-5%; 3. Anti-breakage: The entire layer adopts a weak vibration mode + stainless steel elastic square hole mesh, with a grain breakage rate of <0.5% and a rapeseed breakage rate of <1%; Anti-clogging mesh: Ultrasonic mesh cleaning device + interlayer support mechanism, extending the screen clogging cycle from 2-3 hours to 8-10 hours; Adjustable parameters: The vibration motor shaft inclination angle is infinitely adjustable from 0° to 45°, and the eccentric block angle is adjustable from 0° to 90°, suitable for different materials such as rice, wheat, and rapeseed, avoiding screening dead corners. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is the front view of the present invention; Figure 3 This is a top view of the present invention; Figure 4 This is a cross-sectional structural schematic diagram of the present invention; Figure 5 This is a partially enlarged schematic diagram of the present invention; In the diagram: 1. Base; 2. Outer screen frame; 3. Filter screen; 4. Vibration motor; 5. Interlayer support and tensioning mechanism; 6. Discharge system; 7. Screen cleaning device; 11. Shock absorber; 12. Anchor bolt; 21. Support beam; 22. Sealing strip; 23. Material stop edge; 24. Circular support seat; 25. Side wall support; 41. Adjusting seat; 51. Screen holder; 52. Tensioning bolt; 61. Impurity discharge outlet; 62. Discharge port; 71. Piezoelectric ceramic plate; 72. Electrode plate; 73. Protective cover; 411. Arc-shaped mounting interface; 611. Baffle; 612. Elbow clamp switch; 613. Branch impurity discharge port; 614. Main impurity discharge port; 615. Hinge; 621. Discharge chute. Detailed Implementation

[0017] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0018] In the attached diagram, all identical reference numerals refer to the same components.

[0019] Example 1: Grain Screening Example (Taking Rice as an Example) like Figure 1-5 As shown, this embodiment uses a three-layer filter screen 3 to achieve the grading of rice into large impurities, medium impurities, broken grains and clean grains. The connection relationship and function of the parts are described in detail.

[0020] Overall Structure: The base 1 is a grid-shaped steel structure, with spiral steel spring shock absorbers 11 and adjustable anchor bolts 12 at each of the four corners. The top of the shock absorber 11 is connected to the side wall support 25 of the outer screen frame 2, and the bottom is fixed to the base 1. Its function is to absorb vibration energy, reduce equipment operating noise and ground impact. The adjustable anchor bolts 12 are screwed into the threaded holes at the four corners of the base 1. Their function is to adjust the level of the equipment to adapt to the installation environment. The outer screen frame 2 is inclined above the base 1 and is flexibly connected to the base 1 through the shock absorber 11. The inner side is covered with sealing strips 22 to prevent material leakage during screening. The top feed end is welded with an L-shaped stainless steel baffle 23 to guide the material to fall evenly into the screen 3. A circular support base 24 is welded to the outer side of the outer screen frame 2. The surface of the support base 24 is marked with angle scales to assist in adjusting the angle of the vibrating motor 4 axis.

[0021] Vibration and screen connection and function: The vibration motor 4 consists of two vertical explosion-proof motors, which are symmetrically installed in the middle of the circular support base 24 through the adjustment seat 41; the adjustment seat 41 is provided with an arc-shaped installation interface 411, which is hinged to the circular support base 24. Its function is to realize stepless adjustment of the angle between the axis of the vibration motor 4 and the horizontal plane from 10 to 15 degrees. After adjustment, the angle is fixed by a double locking mechanism (such as bolt locking) to ensure the stability of the vibration direction. The filter screen 3 has three layers, with decreasing aperture from top to bottom, all made of stainless steel elastic square mesh. The support beams 21 of the interlayer support and tensioning mechanism 5 are arranged parallel to the length of the outer screen frame 2, and are fixed to the inner walls of both sides of the outer screen frame 2 by bolts at both ends. The spacing between adjacent support beams 21 is 20 to 25 mm. The function is to divide the inner cavity of the outer screen frame 2 into three layers of screen installation space. The support beams 21 are provided with installation slots, the width of which matches the thickness of the mesh support 51. The mesh support 51 is a stainless steel perforated plate, which is embedded in the installation slots. The function is to support the screen 3 and provide a tensioning reference. The edge of the filter screen 3 is embedded in the U-shaped groove of the mesh support 51. Tensioning bolts 52 are provided at the four corners of the mesh support 51. The tensioning bolts 52 pass through the through holes in the side wall of the outer screen frame 2 and are screwed to the mesh support 51. By tightening the bolts 52, the screen 3 is tensioned and flat. The function is to prevent the screen 3 from loosening and deforming and to ensure screening accuracy.

[0022] Please see the appendix Figure 4 , Figure 5The cleaning and discharge connection and functions are as follows: The cleaning device 7 is integrated under each layer of filter screen 3. It is ultrasonically driven, with a high-frequency generator output frequency of 20-100kHz to ensure cleaning efficiency. The piezoelectric ceramic sheet 71 is a circular sheet that is attached to the back of the filter screen 3. Its function is to remove fine particulate impurities adhering to the back of the screen 3 through high-frequency micro-vibration. The electrode sheet 72 is a copper foil that covers the outside of the piezoelectric ceramic sheet 71 and is connected to the high-frequency generator through a wire. Its function is to conduct current to excite the piezoelectric ceramic sheet 71 to vibrate. The protective cover 73 is a stainless steel mesh cover that covers the piezoelectric ceramic sheet 71 and is bolted to the support beam 21. It is 5 to 10 mm away from the back of the filter screen 3. Its function is to protect the piezoelectric ceramic sheet 71 from material impact while allowing vibration transmission. In the discharge system 6, the impurity discharge outlet 61 is a rectangular hole, which is opened on the corresponding side wall of each layer of screen 3 of the outer screen frame 2. The hole is equipped with a flip-up baffle 611. The baffle 611 is rolledly connected to the side wall of the outer screen frame 2 through hinges 615 on both sides. One side is equipped with an elbow switch 612, which controls the opening and closing of the baffle 611 to achieve directional discharge of impurities. Each layer of screen 3 is equipped with a branch discharge port 613 at the bottom. Each branch discharge port 613 is connected to the main discharge port 614 through a pipe. The function is to collect the impurities separated from each layer. The bottom discharge port 62 is equipped with an inclined discharge chute 621, which is welded to the bottom of the outer screen frame 2. The function is to guide the clean grain to be smoothly discharged into the warehouse.

[0023] Working process: Rice enters the outer screen frame 2 through the L-shaped stainless steel baffle 23. The vibrating motor 4 operates in a weak vibration mode, driving the screen 3 to screen in layers. Large and medium impurities are retained on the corresponding layer of screen 3 and discharged through the baffle 611 of the impurity discharge outlet 61. Broken grains are collected through the branch impurity discharge port 613 into the main impurity discharge port 614. Clean grains pass through the bottom screen 3 and enter the warehouse along the discharge chute 621. The piezoelectric ceramic plate 71 of the screen cleaning device 7 vibrates at high frequency to continuously remove impurities from the back of the screen 3, avoiding clogging and achieving continuous operation.

[0024] This embodiment uses a three-layer model as an example, but it can actually be expanded to six layers (as in Embodiment 2) to adapt to increased production needs.

[0025] Example 2: Rapeseed sieving example, six-layer structure This embodiment adds six layers of filter screen 3 to the existing embodiment 1, focusing on optimizing the sixth layer to solve the problem of impurities in the red and white skin of rapeseed. The connection relationship and function of the newly added layers are described in detail.

[0026] Screen and cleaning screen connection and function: The connection relationship of the first two filter screens 3 is the same as in Example 1, which clean large and medium impurities respectively; the aperture of the third to fifth filter screens 3 decreases, and they are connected and fixed by the support beam 21, the screen holder 51, and the tension bolt 52, which increases the output by 30% to 80%. The sixth filter screen 3 is a stainless steel elastic square hole mesh with a square hole size of 1.2×1.2mm, a hole spacing of 1.5mm, and a thickness of 3mm, which is specifically designed to intercept red and white skin impurities on the surface of rapeseed; its edge is embedded in the U-shaped groove of the screen holder 51 and fixed by the tension bolt 52, which ensures the interception accuracy of the screen 3 for light red and white skin. Each layer of the screen cleaning device 7 is independently controlled. The high-frequency generator of the ultrasonic component in the sixth layer has an output power of 50 to 100W. The piezoelectric ceramic sheet 71 is pasted on the back of the sixth layer screen 3. The electrode sheet 72 conducts current. The protective cover 73 is bolted to the support beam 21 5 to 10 mm away from the back of the screen 3. Its function is to remove red and white skin impurities with high-frequency micro-vibration and the anti-clogging efficiency is >95%.

[0027] Vibration and discharge connection and function: The angle between the axis of the vibration motor 4 and the horizontal plane is adjusted to 10 to 15 degrees. The parameters of the weak vibration mode are set to amplitude 2 to 3 mm, frequency 800 to 1200 rpm, and eccentric block angle 0 to 60 degrees. The function is to reduce the rapeseed breakage rate (<1%). The flip-up baffle 611 of the sixth layer impurity discharge outlet 61 is connected to the outer screen frame 2 through hinge 615. The elbow switch 612 controls the opening and closing. Red and white skin impurities are collected by the branch impurity discharge port 613 to the main impurity discharge port 614. The collection rate is over 98%.

[0028] Results: 40 tons of rapeseed are processed per hour, with impurity content <1% and breakage rate <1%, meeting the high-quality requirements for oil extraction.

[0029] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-layer vibrating screen for fine particle screening, characterized in that, include: The base (1) is equipped with a shock absorber (11) and adjustable anchor bolts (12). The outer screen frame (2) is inclinedly set on the base (1) and connected to the base (1) through the shock absorber (11). It has at least three layers of filter screens (3) inside, and the layers are separated by interlayer support and tensioning mechanism (5). The inner side of the outer screen frame (2) is provided with sealing strip (22), the top feed end is provided with L-shaped stainless steel baffle (23), and the side is provided with side wall support (25). The vibrating motor (4) is installed on the outside of the outer screen frame (2), and the angle between its axis and the horizontal plane is infinitely adjustable from 0° to 45° through the adjusting seat (41); The interlayer support and tensioning mechanism (5) is located inside the outer screen frame (2) and includes a parallel support beam (21), a mesh support (51) and a tensioning bolt (52); the support beam (21) extends along the length of the outer screen frame (2) and divides the inner cavity of the outer screen frame (2) into at least three layers of screen installation space; A screen cleaning device (7) is integrated below each layer of the filter screen (3); The discharge system (6) includes a discharge outlet (61) provided on the side wall of each layer of filter screen (3) of the outer screen frame (2) and a discharge port (62) provided at the bottom of the outer screen frame (2). The filter screen (3) is a small-aperture woven mesh or stainless steel elastic square mesh, with the aperture of each layer decreasing from top to bottom; the vibration motor (4) operates in a weak vibration mode, and its amplitude, frequency, eccentric block angle and the angle between the axis and the horizontal plane are adapted to the fine particle anti-breakage screening requirements.

2. A multi-layer vibrating screen for fine particle screening according to claim 1, characterized in that, The outer screen frame (2) is bolted to the side wall support (25) of the base (1) via an adjusting screw and the shock absorber (11); the shock absorber (11) is a spiral steel spring shock absorber, and its top end is connected to the side wall support (25).

3. A multi-layer vibrating screen for fine particle screening according to claim 1, characterized in that, The length of the support beam (21) of the interlayer support and tensioning mechanism (5) matches the inner width of the outer screen frame (2), and both ends are fixedly connected to the two sides of the outer screen frame (2) by bolts; the spacing between adjacent support beams (21) is 20-25mm, and the support beam (21) is provided with an installation slot, the width of which matches the thickness of the mesh support (51).

4. A multi-layer vibrating screen for fine particle screening according to claim 1, characterized in that, The mesh support (51) of the interlayer support and tensioning mechanism (5) is a stainless steel perforated plate, which is embedded in the mounting slot of the support beam (21); the edge of the filter screen (3) is embedded in the U-shaped slot of the mesh support (51) and fixed by the tensioning bolts (52) at the four corners of the mesh support (51). The tensioning bolts (52) pass through the through hole of the side wall of the outer screen frame (2) and are screwed to the mesh support (51).

5. A multi-layer vibrating screen for fine particle screening according to claim 1, characterized in that, The vibration motor (4) is a vertical explosion-proof motor, which is symmetrically installed on the middle of the circular support base (24) on the outer side of the outer screen frame (2) through the adjustment base (41); the circular support base (24) is provided with an angle scale, and the adjustment base (41) has an arc-shaped installation interface (411) and a motor installation hole in the middle, so as to realize stepless adjustment of the angle between the axis of the vibration motor (4) and the horizontal plane, and after adjustment, it is fixed by a double locking mechanism; preferably, there are two vibration motors (4) arranged symmetrically.

6. A multi-layer vibrating screen for fine particle screening according to claim 1, characterized in that, The cleaning device (7) is ultrasonically driven and includes a piezoelectric ceramic sheet (71), an electrode sheet (72), and a protective cover (73) integrated under each layer of the filter screen (3). The piezoelectric ceramic sheet (71) is a circular sheet that is pasted on the back of the filter screen (3) and removes fine particulate impurities through high-frequency micro-vibration. The electrode sheet (72) is a copper foil that covers the outside of the piezoelectric ceramic sheet (71) and is connected to a high-frequency generator through a wire. The protective cover (73) is a stainless steel mesh cover that covers the piezoelectric ceramic sheet (71) and is bolted to the support beam (21) at a distance of 5-10 mm from the back of the filter screen (3).

7. A multi-layer vibrating screen for fine particle screening according to claim 6, characterized in that, Each layer of the filter screen (3) is provided with a set of ultrasonic cleaning components below it. Each set of components includes the piezoelectric ceramic sheet (71), electrode sheet (72) and protective cover (73). Each set of components is connected to the control box through wires and can be started and stopped independently. The high frequency generator outputs 50-100W.

8. A multi-layer vibrating screen for fine particle screening according to claim 1, characterized in that, The discharge outlet (61) of the discharge system (6) is a side wall slag discharge port, which is a rectangular hole opened on the corresponding side wall of each layer of filter screen (3) of the outer screen frame (2); the discharge outlet (61) is provided with a flip-up baffle (611), the baffle (611) is connected to the outer screen frame (2) by hinges (615) on both sides, and an elbow switch (612) is provided on one side; each layer of filter screen (3) is provided with a branch discharge port (613) at the bottom, and each branch discharge port (613) converges to the main discharge port (614); the discharge port (62) includes a discharge trough (621) inclinedly set at the bottom of the outer screen frame (2).

9. A multi-layer vibrating screen for fine particle screening according to claim 1, characterized in that, The filter screen (3) is a stainless steel elastic square hole screen with a square hole size of 4×4mm, a hole spacing of 5mm, and a thickness of 5mm; the vibration motor (4) in the weak vibration mode has an amplitude of 2-3mm, a frequency of 800-1200rpm, an eccentric block angle of 0°-90°, an excitation force of 2-5kN per motor, and an angle of 10°-15° between the axis and the horizontal plane.

10. A multi-layer vibrating screen for fine particle screening according to claim 1, characterized in that, The base (1) is a grid-shaped steel structure, with the spiral steel spring shock absorber (11) and the adjustable anchor bolt (12) installed at the four corners.

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