Agricultural seed particle size screening device and method for seedling raising

Abstract

The application provides a seed particle size screening device for agricultural planting and seedling raising, which comprises a primary screening mechanism and a fine screening mechanism, the inlet of the primary screening mechanism is communicated with a feeding device, and the outlet of the primary screening mechanism is communicated with the fine screening mechanism; the primary screening mechanism comprises an outer cylinder and an inner cylinder, the inner cylinder is rotatably installed in the outer cylinder, a primary screening net is arranged on the side wall of the inner cylinder, and the outer cylinder is communicated with the fine screening mechanism through a seed suction pipe; the fine screening mechanism comprises a fine screening box, a plurality of grading and screening assemblies are sequentially arranged in the fine screening box, each grading and screening assembly comprises a seed shaking groove, a swing driving mechanism and a fan, the swing driving mechanism is connected with the seed shaking groove to drive the seed shaking groove to swing reciprocate in the fine screening box, a fine screening net is arranged on the bottom surface of the seed shaking groove, and the fan is installed on one side of the seed shaking groove. The application also provides a screening method mainly comprising primary screening centrifugal layering, air separation impurity removal and vibration fine screening. The application has scientific and reasonable structure design, good screening effect, high screening efficiency, can effectively reduce the labor cost of seed screening, and can be widely used.

Description

Technical Field

[0001] This invention relates to a seed screening device, specifically to a seed particle size screening device and screening method for agricultural planting and seedling cultivation. Background Technology

[0002] In agricultural seedling cultivation, seed quality directly affects seedling growth and development, as well as the final yield and quality of crops. Seed size uniformity is a crucial indicator, as seeds of different sizes may exhibit differences in germination speed and growth vigor. For instance, larger seeds typically store more nutrients and grow faster in the initial stages after germination; conversely, smaller seeds may germinate more slowly, and seedlings may grow weaker. To ensure uniform and robust seedling growth during the cultivation process, seeds need to be sieved by size, classifying them according to their different sizes for appropriate sowing and cultivation based on their characteristics.

[0003] Traditional seed screening devices rely on manual operation or simple mechanical vibration for screening, which is labor-intensive, time-consuming, and slow, failing to meet the efficiency requirements of large-scale agricultural planting and seedling cultivation. Therefore, there is a need to design a device capable of quickly and efficiently screening large quantities of seeds by particle size, thereby improving production efficiency and reducing labor costs. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a seed particle size screening device for agricultural planting and seedling cultivation, which addresses the shortcomings of the prior art. The device has a scientific and reasonable structural design, good screening effect, high screening efficiency, and minimal damage to seeds, effectively reducing the labor cost of seed screening and can be widely used.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a seed particle size screening device for agricultural planting and seedling cultivation, characterized in that it includes a primary screening mechanism and a fine screening mechanism, wherein the inlet of the primary screening mechanism is connected to a feeding device and the outlet of the primary screening mechanism is connected to the fine screening mechanism. The primary screening mechanism includes an outer cylinder and an inner cylinder. The inner cylinder is rotatably installed inside the outer cylinder. A primary screening motor that drives the inner cylinder to rotate is fixedly installed on the outer cylinder. A primary screening cavity is provided between the outer cylinder and the inner cylinder. A primary screening screen is provided on the side wall of the inner cylinder. The outer cylinder is connected to the fine screening mechanism through multiple seed suction pipes. A seed suction pump is installed on the seed suction pipes. The fine screening mechanism includes a fine screening box, in which multiple grading screening components are arranged sequentially from top to bottom. Each grading screening component is connected to a seed suction tube. Each grading screening component includes a seed shaking trough, a swing drive mechanism, and a fan. The swing drive mechanism is connected to the seed shaking trough and drives the seed shaking trough to swing back and forth within the fine screening box. A fine screen is provided on the bottom surface of the seed shaking trough. A seed collection tray is provided below each seed shaking trough in the fine screening box. A fan is installed on one side of the seed shaking trough, and a cleanup door is provided on the opposite side of the seed shaking trough from the fan.

[0006] Preferably, two sets of swing drive mechanisms are symmetrically arranged on both sides of one of the seed-shaking troughs. The swing drive mechanism includes an incomplete gear and a limiting ring. The limiting ring is a racetrack-shaped metal ring. The inner ring of the limiting ring is symmetrically provided with an internal rack. The internal rack meshes with the gear teeth on the incomplete gear. The incomplete gear is rotatably installed in the fine sieve box through a positioning shaft. The inner side of the limiting ring is fixedly connected to the seed-shaking trough, and the outer side of the limiting ring is slidably connected to the fine sieve box.

[0007] Preferably, the bottom of the outer ring of the limiting ring is provided with an external rack, which meshes with an auxiliary rocking gear. The auxiliary rocking gear is connected to the seed-shaping groove. Two connecting rods are symmetrically fixedly connected to the inner side of the limiting ring. The connecting rods are fixedly connected to the outer wall of the seed-shaping groove through an upper guide rod. A support shaft is coaxially fixedly connected to the auxiliary rocking gear. One end of the support shaft is rotatably mounted on the inner wall of the fine sieve box. The other end of the support shaft passes through the auxiliary rocking gear and is rotatably connected to one end of a connecting rod. The other end of the connecting rod is rotatably connected to a lower guide rod.

[0008] Preferably, the grading and screening component further includes a power component, which includes a fine screening motor, a tensioning wheel, and a drive shaft. The two ends of the drive shaft are rotatably mounted on the inner wall of the fine screening box. One drive shaft is connected to the fine screening motor, and adjacent drive shafts are connected to each other. The drive shaft is connected to an incomplete gear.

[0009] Preferably, a driven bevel gear is provided at the middle position of one of the drive shafts, and a worm gear is provided at the middle position of the other drive shafts. A driving bevel gear that meshes perpendicularly with the driven bevel gear is provided on the power shaft of one of the fans, and worm gears that cooperate with the worm gear are provided on the power shafts of the other fans. The driving bevel gear is coaxially and fixedly connected to the output shaft of the fine screen motor. A swing drive wheel is provided at both ends of the drive shaft. A swing driven wheel is coaxially and fixedly sleeved on the positioning shaft. The swing drive wheel is connected to the swing driven wheel through a swing drive belt. A tension wheel for adjusting the tension of the swing drive belt is provided in the fine screen box. The two ends of the tension wheel are rotatably connected to the telescopic rod of the telescopic cylinder through bearings. The base of the telescopic cylinder is fixedly installed in the fine screen box. One or more synchronous pulleys are provided on the drive shaft, and the synchronous pulleys on adjacent drive shafts are connected by synchronous belt transmission.

[0010] Preferably, the seed shaking trough is provided with an airflow mesh for the fan to blow air into the seed shaking trough, and the impurity removal door is an electric gate valve.

[0011] Preferably, a limiting groove is formed on the inner wall of the fine sieve box, and multiple limiting rods are fixedly connected to the outer side of the limiting ring. The limiting rods are provided with sliders that slide in cooperation with the limiting groove.

[0012] Preferably, the bottom of the outer cylinder is connected to an impurity collection box via an impurity collection port, a magnetic suction pump is installed at the bottom of the outer cylinder, the outlet of the magnetic suction pump is connected to the impurity collection port, and an electric cover plate is installed at the top of the outer cylinder.

[0013] Preferably, the feeding device is a feeding conveyor belt, the material outlet of the feeding device is located directly above the inner cylinder, the outlets of the multiple seed suction pipes are respectively located directly above the seed shaking trough, and the impurity removal movable door is connected to the impurity box through a flexible hose.

[0014] Preferably, the fan speed is controlled by controlling the speed of the fine screen motor to improve the separation effect of impurities of different sizes and shapes.

[0015] Preferably, the mesh size of the fine screens in the multi-layer seed shaking trough increases sequentially. Two fine screens with different mesh sizes are symmetrically and detachably installed on both sides of the bottom of a single seed shaking trough. An electric gate valve is installed on the fine screen, and the two fine screens open and close alternately at 10-second intervals. A sliding pull-out seed collection tray is installed below each fine screen.

[0016] A method for sieving the particle size of seeds used in agricultural planting and seedling cultivation, characterized by comprising the following steps: S1. Initial screening and centrifugal stratification: The feeding device conveys the seeds to be screened into the inner cylinder, closes the electric cover, starts the initial screening motor, and the seeds are stratified by weight under the action of centrifugal force. The seed suction pump is turned on, and the stratified seeds are sent to the corresponding seed shaking tank by the seed suction pipes of different heights. The mud and sand impurities at the bottom are pumped into the impurity collection box. S2, Air separation for impurity removal: Control the telescopic cylinder to loosen the tension wheel and reduce the tension of the swing drive belt. At this time, the swing driven wheel does not rotate synchronously with the swing drive wheel. Start the fine screen motor and multiple fans rotate to blow small impurities and shriveled seeds out of the impurity removal door to the impurity box. S3, Vibrating Fine Screen: The drive telescopic cylinder causes the tension wheel to tighten the swing drive belt, the swing driven wheel rotates synchronously with the swing drive wheel, the incomplete gear rotates and drives the limit ring to swing, so that the seed trough swings accordingly to complete the fine screening of seeds.

[0017] Compared with the prior art, the present invention has the following advantages: 1. This invention uses a motor-driven primary screening mechanism to rotate at high speed, causing seeds to separate into layers according to weight. Heavier seeds settle to the bottom and are filtered for impurities through a replaceable primary screen, solving the problems of low efficiency and seed damage associated with traditional vibrating screening. Combined with wind speed grading control, it precisely removes empty shells and inferior seeds, significantly improving seed purity. The time-sharing transmission system reduces the motor load.

[0018] 2. This invention controls the transmission relationship between the driven wheel and the driving wheel of the oscillating mechanism by adjusting the tension, achieving a stationary oscillating trough during air separation and power transmission during sieving, thus avoiding mechanical damage to seeds, such as breakage due to continuous vibration, caused by collisions, in traditional equipment. During secondary sieving, the ventilation cover is closed to maintain a dry environment inside the chamber, while continuous ventilation prevents mold growth.

[0019] 3. This invention supports the grading requirements of seeds of different particle sizes, such as wheat and corn. By adjusting the screen aperture and wind speed, it adapts to the seedling needs of multiple crops, reduces manual intervention, has high screening efficiency, and the screened seeds have a high degree of germination synchronization and uniform seedlings.

[0020] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0022] Figure 2 This is a cross-sectional structural diagram of the primary screening mechanism in this invention.

[0023] Figure 3 This is a schematic diagram of the connection between the primary screening mechanism and the fine screening mechanism in this invention.

[0024] Figure 4 This is a schematic diagram of the main structure of the fine screening mechanism in this invention.

[0025] Figure 5 This is a three-dimensional structural diagram of the fine screening mechanism in this invention.

[0026] Figure 6 This is a three-dimensional structural diagram of the graded screening component in this invention.

[0027] Figure 7 This is a three-dimensional structural diagram of the seed-shaking trough and the swing drive mechanism in this invention.

[0028] Explanation of reference numerals in the attached figures: Detailed Implementation

[0029] Example 1 like Figures 1 to 7As shown, this embodiment provides a seed particle size screening device for agricultural planting and seedling raising, including a primary screening mechanism 1 and a fine screening mechanism 2. The inlet of the primary screening mechanism 1 is connected to a feeding device 3, and the outlet of the primary screening mechanism 1 is connected to the fine screening mechanism 2. The primary screening mechanism 1 includes an outer cylinder 1-1 and an inner cylinder 1-2. The inner cylinder 1-2 is rotatably installed inside the outer cylinder 1-1. A primary screening motor 1-3 for driving the inner cylinder 1-2 to rotate is fixedly installed on the outer cylinder 1-1. A primary screening cavity 1-4 is provided between the outer cylinder 1-1 and the inner cylinder 1-2. A primary screening screen 1-5 is provided on the side wall of the inner cylinder 1-2. The outer cylinder 1-1 is connected to the fine screening mechanism 2 from top to bottom through three seed suction pipes 1-6. A seed suction pump 1-7 is installed on the seed suction pipes 1-6. The fine screening mechanism 2 includes a fine screening box 2-1. Three grading screening components are arranged sequentially from top to bottom inside the fine screening box 2-1. Each grading screening component is connected to a seed suction tube 1-6. Each grading screening component includes a seed shaking trough 2-2, a swinging drive mechanism, and a fan 2-3. The swinging drive mechanism connects to the seed shaking trough 2-2 and drives it to swing back and forth within the fine screening box 2-1. A fine screen 2-4 is provided on the bottom surface of the seed shaking trough 2-2. A seed collection tray 2-5 is provided below each seed shaking trough 2-2 within the fine screening box 2-1. A fan 2-3 is installed on one side of each seed shaking trough 2-2, and a cleanup door 2-6 is provided on the opposite side of the seed shaking trough 2-2 relative to the fan 2-3.

[0030] In this embodiment, two sets of swing drive mechanisms are symmetrically arranged on both sides of one of the seed-shaking troughs 2-2. The swing drive mechanism includes an incomplete gear 2-7 and a limiting ring 2-8. The limiting ring 2-8 is a racetrack-shaped metal ring. An internal rack 2-10 is symmetrically arranged on the inner ring of the limiting ring 2-8. The internal rack 2-10 meshes with the gear teeth on the incomplete gear 2-7. The incomplete gear 2-7 is rotatably installed in the fine sieve box 2-1 through a positioning shaft 2-11. The inner side of the limiting ring 2-8 is fixedly connected to the seed-shaking trough 2-2, and the outer side of the limiting ring 2-8 is slidably connected to the fine sieve box 2-1.

[0031] In this embodiment, an outer rack 2-12 is provided at the bottom of the outer ring of the limiting ring 2-8. The outer rack 2-12 meshes with an auxiliary rocking gear 2-13. The auxiliary rocking gear 2-13 is connected to the seed-shaking groove 2-2. Two connecting rods 2-14 are symmetrically fixedly connected to the inner side of the limiting ring 2-8. The connecting rods 2-14 are fixedly connected to the outer wall of the seed-shaking groove 2-2 through an upper guide rod 2-15. A support shaft 2-15 is coaxially fixedly connected to the auxiliary rocking gear 2-13. One end of the support shaft 2-15 is rotatably mounted on the inner wall of the fine sieve box 2-1. The other end of the support shaft 2-15 passes through the auxiliary rocking gear 2-13 and is rotatably connected to one end of a connecting rod 2-16. The other end of the connecting rod 2-16 is rotatably connected to a lower guide rod 2-17.

[0032] In this embodiment, the grading and screening component further includes a power component, which includes a fine screen motor 2-18, a tensioning wheel 2-19, and a drive shaft 2-20. The two ends of the drive shaft 2-20 are rotatably mounted on the inner wall of the fine screen box 2-1. One drive shaft 2-20 is connected to the fine screen motor 2-18, and adjacent drive shafts 2-20 are connected to each other. The drive shaft 2-20 is connected to an incomplete gear 2-7.

[0033] In this embodiment, a driven bevel gear is installed at the middle position of the lowest transmission shaft 2-20, and worm gears 2-21 are installed at the middle positions of the other two transmission shafts 2-20. A driving bevel gear 2-23, perpendicularly meshing with the driven bevel gear, is installed on the power shaft of the lowest fan 2-3. Worm gears 2-22, cooperating with the worm gear 2-21, are installed on the power shafts of the other fans 2-3. The driving bevel gear 2-23 is coaxially and fixedly connected to the output shaft of the fine screen motor 2-18. Swing drive wheels 2-24 are installed at both ends of the transmission shaft 2-20. A swing driven wheel 2-26 is coaxially and fixedly sleeved on the positioning shaft 2-11. The driving wheel 2-24 is connected to the driven wheel 2-26 via the swing drive belt 2-25. The fine sieve box 2-1 is equipped with a tension wheel 2-19 for adjusting the tension of the swing drive belt 2-25. The two ends of the tension wheel 2-19 are rotatably connected to the telescopic rod of the telescopic cylinder 2-28 via bearings. The base of the telescopic cylinder 2-28 is fixedly installed inside the fine sieve box 2-1. A synchronous pulley 2-29 is provided on the bottommost and topmost drive shafts 2-20, and two synchronous pulleys 2-29 are provided on the middle drive shaft 2-20. The synchronous pulleys 2-29 on adjacent drive shafts 2-20 are connected by a synchronous belt 2-30.

[0034] In this embodiment, the seed shaking trough 2-2 is provided with an airflow mesh 2-31 for the fan 2-3 to blow airflow into the seed shaking trough 2-2, and the impurity removal movable door 2-6 is an electric gate valve.

[0035] In this embodiment, a limiting groove 2-32 is provided on the inner wall of the fine sieve box 2-1, and multiple limiting rods 2-27 are fixedly connected to the outer side of the limiting ring 2-8. A slider 2-9 is provided on the limiting rod 2-27 to slide in cooperation with the limiting groove 2-32.

[0036] In this embodiment, the bottom of the outer cylinder 1-1 is connected to the impurity collection box 1-8 through the impurity collection port, a magnetic suction pump 1-9 is installed at the bottom of the outer cylinder 1-1, the outlet of the magnetic suction pump 1-9 is connected to the impurity collection port, and an electric cover plate is installed at the top of the outer cylinder 1-1.

[0037] In this embodiment, the feeding device 3 is a feeding conveyor belt, the material outlet of the feeding device 3 is located directly above the inner cylinder 1-2, the outlets of the multiple seed suction pipes 1-6 are respectively located directly above the seed shaking trough 2-2, and the impurity removal movable door 2-6 is connected to the impurity box through a flexible hose.

[0038] In this embodiment, the speed of the fan 2-3 is controlled by controlling the speed of the fine screen motor 2-18 to improve the separation effect of impurities of different sizes and shapes.

[0039] In this embodiment, the mesh size of the fine screens 2-4 in the multi-layer seed shaking trough 2-2 increases sequentially. Two fine screens 2-4 with different mesh sizes are symmetrically and detachably installed on both sides of the bottom of a single seed shaking trough 2-2. An electric gate valve is installed on the fine screen 2-4, and the two fine screens 2-4 on both sides open and close alternately at 10-second intervals. A sliding pull-out seed collection tray 2-5 is correspondingly installed below each fine screen 2-4.

[0040] Example 2 This embodiment provides a method for sieving the particle size of seeds used in agricultural planting and seedling cultivation, including the following steps: S1. Initial screening and centrifugal stratification: The feeding device 3 conveys the seeds to be screened into the inner cylinder 1-2, closes the electric cover, starts the initial screening motor 1-3, and the seeds are stratified by weight under the action of centrifugal force. The seed suction pump 1-7 is turned on, and the stratified seeds are sent to the corresponding seed shaking trough 2-2 by the seed suction pipes 1-6 of different heights. The mud and sand impurities at the bottom are pumped into the impurity collection box 1-8. S2, Air separation for impurity removal: Control the telescopic cylinder 2-28 to loosen the tension wheel 2-19 and reduce the tension of the swing drive belt 2-25. At this time, the swing driven wheel 2-26 does not rotate synchronously with the swing drive wheel 2-24. Start the fine screen motor 2-18 and multiple fans 2-3 rotate to blow out small impurities and shriveled seeds from the impurity removal door 2-6 to the impurity box. S3, Vibrating Fine Screen: Drive the telescopic cylinder 2-28 to make the tensioning wheel 2-19 tighten the swing drive belt 2-25. The swing driven wheel 2-26 rotates synchronously with the swing drive wheel 2-24. The incomplete gear 2-7 rotates and intermittently meshes with the internal gear rack 2-10, which drives the limit ring 2-8 to swing, so that the seed shaking trough 2-2 swings accordingly to complete the fine screening of seeds.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A seed particle size screening device for agricultural planting and seedling cultivation, characterized in that, It includes a primary screening mechanism (1) and a fine screening mechanism (2), wherein the inlet of the primary screening mechanism (1) is connected to a feeding device (3) and the outlet of the primary screening mechanism (1) is connected to the fine screening mechanism (2). The primary screening mechanism (1) includes an outer cylinder (1-1) and an inner cylinder (1-2). The inner cylinder (1-2) is rotatably installed inside the outer cylinder (1-1). A primary screening motor (1-3) for driving the inner cylinder (1-2) to rotate is fixedly installed on the outer cylinder (1-1). A primary screening cavity (1-4) is provided between the outer cylinder (1-1) and the inner cylinder (1-2). A primary screening screen (1-5) is provided on the side wall of the inner cylinder (1-2). The outer cylinder (1-1) is connected to the fine screening mechanism (2) through multiple seed suction pipes (1-6). A seed suction pump (1-7) is installed on the seed suction pipes (1-6). The fine screening mechanism (2) includes a fine screening box (2-1). Multiple graded screening components are arranged sequentially from top to bottom inside the fine screening box (2-1). Each graded screening component is connected to a seed suction tube (1-6). The graded screening components include a seed shaking trough (2-2), a swing drive mechanism, and a fan (2-3). The swing drive mechanism is connected to the seed shaking trough (2-2) and drives the seed shaking trough (2-2) to swing back and forth inside the fine screening box (2-1). A fine screen (2-4) is arranged on the bottom surface of the seed shaking trough (2-2). A seed collection tray (2-5) is arranged below each seed shaking trough (2-2) inside the fine screening box (2-1). A fan (2-3) is installed on one side of the seed shaking trough (2-2), and a cleanup door (2-6) is arranged on the other side of the seed shaking trough (2-2) opposite to the fan (2-3). Two sets of swing drive mechanisms are symmetrically arranged on both sides of the seed-shaking trough (2-2). The swing drive mechanism includes an incomplete gear (2-7) and a limiting ring (2-8). The limiting ring (2-8) is a racetrack-shaped metal ring. An internal rack (2-10) is symmetrically arranged on the inner ring of the limiting ring (2-8). The internal rack (2-10) meshes with the gear teeth on the incomplete gear (2-7). The incomplete gear (2-7) is rotatably installed in the fine sieve box (2-1) through a positioning shaft (2-11). The inner side of the limiting ring (2-8) is fixedly connected to the seed-shaking trough (2-2), and the outer side of the limiting ring (2-8) is slidably connected to the fine sieve box (2-1). The bottom of the outer ring of the limiting ring (2-8) is provided with an outer rack (2-12), which meshes with the auxiliary rocking gear (2-13). The auxiliary rocking gear (2-13) is connected to the seed-shaking trough (2-2). Two connecting rods (2-14) are symmetrically fixedly connected to the inner side of the limiting ring (2-8). The connecting rods (2-14) are fixedly connected to the outer wall of the seed-shaking trough (2-2) through the upper guide rod (2-15). A support shaft is coaxially fixedly connected to the auxiliary rocking gear (2-13). One end of the support shaft is rotatably mounted on the inner wall of the fine sieve box (2-1). The other end of the support shaft passes through the auxiliary rocking gear (2-13) and rotatably connects to one end of the connecting rod (2-16). The other end of the connecting rod (2-16) is rotatably connected to the lower guide rod (2-17). The grading and screening assembly also includes a power assembly, which includes a fine screen motor (2-18), a tensioning wheel (2-19), and a drive shaft (2-20). The two ends of the drive shaft (2-20) are rotatably mounted on the inner wall of the fine screen box (2-1). One drive shaft (2-20) is connected to the fine screen motor (2-18), and adjacent drive shafts (2-20) are connected to each other. The drive shaft (2-20) is connected to an incomplete gear (2-7). A driven bevel gear is installed at the middle position of one of the drive shafts (2-20), and a worm gear (2-21) is installed at the middle position of the other drive shafts (2-20). One fan (2-3) has a driving bevel gear (2-23) that meshes perpendicularly with the driven bevel gear on its power shaft. The other fans (2-3) have worm wheels (2-22) that mesh with the worm gear (2-21) on their power shafts. The driving bevel gear (2-23) is coaxially and fixedly connected to the output shaft of the fine screening motor (2-18). Swing drive wheels (2-24) are installed at both ends of the drive shafts (2-20). A swing driven wheel (2-24) is coaxially and fixedly sleeved on the positioning shaft (2-11). 26) The swing drive wheel (2-24) is connected to the swing driven wheel (2-26) via the swing drive belt (2-25). The fine sieve box (2-1) is provided with a tension wheel (2-19) for adjusting the tension of the swing drive belt (2-25). The two ends of the tension wheel (2-19) are rotatably connected to the telescopic rod of the telescopic cylinder (2-28) via bearings. The base of the telescopic cylinder (2-28) is fixedly installed in the fine sieve box (2-1). One or more synchronous pulleys (2-29) are provided on the drive shaft (2-20). The synchronous pulleys (2-29) on adjacent drive shafts (2-20) are connected by a synchronous belt (2-30).

2. The seed particle size screening device for agricultural planting and seedling raising according to claim 1, characterized in that, The seed-shaking trough (2-2) is provided with an airflow mesh (2-31) for the fan (2-3) to blow airflow into the seed-shaking trough (2-2), and the impurity removal movable door (2-6) is an electric gate valve.

3. The seed particle size screening device for agricultural planting and seedling raising according to claim 1, characterized in that, A limiting groove (2-32) is provided on the inner wall of the fine sieve box (2-1). Multiple limiting rods (2-27) are fixedly connected to the outer side of the limiting ring (2-8). A slider (2-9) is provided on the limiting rod (2-27) to slide in cooperation with the limiting groove (2-32).

4. The seed particle size screening device for agricultural planting and seedling raising according to claim 1, characterized in that, The bottom of the outer cylinder (1-1) is connected to the impurity collection box (1-8) through the impurity collection port. A magnetic suction pump (1-9) is installed at the bottom of the outer cylinder (1-1). The outlet of the magnetic suction pump (1-9) is connected to the impurity collection port. An electric cover plate is installed at the top of the outer cylinder (1-1).

5. The seed particle size screening device for agricultural planting and seedling raising according to claim 1, characterized in that, The feeding device (3) is a feeding conveyor belt. The material outlet of the feeding device (3) is located directly above the inner cylinder (1-2). The outlets of the multiple seed suction pipes (1-6) are located directly above the seed shaking trough (2-2). The impurity removal door (2-6) is connected to the impurity box through a hose.

6. A method for seed sieving using the seed particle size sieving device for agricultural planting and seedling raising as described in claim 4, characterized in that, Includes the following steps: S1. Initial screening and centrifugal stratification: The feeding device (3) transports the seeds to be screened into the inner cylinder (1-2), closes the electric cover, starts the initial screening motor (1-3), and the seeds are stratified by weight under the action of centrifugal force. The seed suction pump (1-7) is turned on, and the stratified seeds are sent to the corresponding seed shaking tank (2-2) by the seed suction pipes (1-6) of different heights. The mud and sand impurities at the bottom are pumped into the impurity collection box (1-8). S2, Air separation for impurity removal: Control the telescopic cylinder (2-28) to loosen the tension wheel (2-19) and reduce the tension of the swing drive belt (2-25). At this time, the swing driven wheel (2-26) does not rotate synchronously with the swing drive wheel (2-24). Start the fine screen motor (2-18), and multiple fans (2-3) rotate to blow small impurities and shriveled seeds out of the impurity removal door (2-6) to the impurity box. S3, Vibrating fine screening: Drive the telescopic cylinder (2-28) to tighten the swing drive belt (2-25) with the tension wheel (2-19). The swing driven wheel (2-26) rotates synchronously with the swing drive wheel (2-24). The incomplete gear (2-7) rotates and drives the limit ring (2-8) to swing, so that the seed shaking trough (2-2) swings accordingly to complete the fine screening of seeds.

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