A catfish grading apparatus

Abstract

The present application relates to aquatic processing technical field, specifically, it is a kind of eel grading device, including feed disc, grading device and transmission device, grading device is located below feed disc, transmission device is used to provide power for the rotation of grading device;Grading device includes large cylinder and multiple grading small cylinders, large cylinder is sleeved in grading small cylinder, and gap is left between the two;Grading small cylinder is provided with fish conveying port, and the fish conveying port is communicated with the conical structure of the next stage grading small cylinder through the corresponding grading small cylinder inner cavity;The outer periphery of grading small cylinder is provided with helical blade, and the top end is communicated with conical structure, and the bottom end is communicated with fish conveying port;The gap between large cylinder and grading small cylinder is greater than the maximum width of finished product eel;From top to bottom, the gap between the helical blade of grading small cylinder and the large cylinder gradually increases.The present application can be adapted to multiple specifications of rice field eel, and has high grading precision, good grading fault tolerance, compact structure, and great popularization value.

Description

Technical Field

[0001] This invention relates to the field of aquatic product sorting and processing technology, specifically to an eel grading device. This device is applicable to the automated grading and sorting of live eels of different lengths and sizes, and is suitable for large-scale sorting scenarios in aquaculture, fresh processing, and aquatic product sales. Background Technology

[0002] The sale, processing, and breeding of eels all require grading according to size. Eels of different sizes have significant differences in market price, cooking purpose, processing technology, and breeding methods. Mixed sizes of eels will seriously affect the quality of fresh eels and the qualification rate of processed products. Therefore, accurate and efficient grading and sorting is a key pre-processing step in the industrialization of eel processing.

[0003] With the development of aquatic product processing equipment technology, several eel grading devices have emerged in recent years. For example, patent CN207836517U discloses an eel grading device, including a forward-leaning main frame and a grading grid composed of several parallel grading shafts. The grading shafts have a circular cross-section and are equipped with baffles and guide plates to form a funnel-shaped eel outlet. This device has a certain degree of adjustability and effectively solves problems such as overlapping eel outlets and potential secondary mixing after grading. Another example is a roller-type vibrating eel grading device designed in academic research. This device utilizes the synergistic effect of vibration and spraying to grade eels, achieving a measured grading efficiency of 0.637 eels / s and an average grading accuracy of 86.7%. Furthermore, patent CN211832426U discloses a live fish grading and screening device, employing a spiral screening cylinder structure. Fish slide towards the end with the larger screw pitch inside the cylinder and fall into the corresponding collection box through the gaps in the screw pitch, thus achieving grading and screening.

[0004] However, the aforementioned existing technologies still have many shortcomings. First, the grading shaft grid device is a horizontal grading device, which is not very effective for grading smaller juvenile eels. Larger eels may carry smaller juvenile eels into the large eel collection box. Second, the grading accuracy of the vibration grading device is only about 86.7%, leaving considerable room for improvement. The spiral screening cylinder grading device is mainly designed for general fish and lacks specific adaptation to the slimy characteristics of eels caused by their body mucus and the differences in individual morphology. In addition, existing grading equipment is mostly single-function grading equipment, lacking integrated design with cleaning, collection and other processes. Overall, it suffers from energy waste, low operating efficiency, and low sorting qualification rate, significantly increasing the production cost of eel farming and processing, and seriously restricting the large-scale and standardized development of eel aquaculture and fresh processing industries.

[0005] Therefore, there is an urgent need for a rolling eel grading device that can adapt to eels of various sizes, has high grading accuracy, good grading error tolerance, and a compact structure, in order to promote the large-scale and standardized development of the eel processing industry. Summary of the Invention

[0006] The purpose of this invention is to provide an eel grading device to solve the technical problems of poor adaptability of existing grading equipment to eels of different sizes, low grading accuracy, and low operating efficiency.

[0007] A grading device for eels includes a feeding disc with an opening, a grading device, and a transmission device. The grading device is located below the opening of the feeding disc, and the transmission device is used to provide power for the rotation of the grading device. The grading device includes a large cylinder and multiple smaller grading cylinders. The large cylinder is fitted over the smaller grading cylinders, and the multiple smaller grading cylinders are coaxially connected. The top of each smaller grading cylinder is an upwardly convex conical structure, and an annular blade is connected to the outer circumference of its bottom. The outer diameter of the annular blade is not greater than the inner diameter of the large cylinder, and the gap between them is less than the minimum width of the eel (preferably not more than 1 cm). Multiple fish outlet grooves are formed on the circumference of the large cylinder, and each fish outlet groove corresponds to one of the annular blades. The lower circumferential surface of the grading cylinder is also provided with a fish transfer port, which is connected to the conical structure of the next grading cylinder through the inner cavity of the corresponding grading cylinder; the outer circumferential surface of the grading cylinder is provided with a spiral blade, the top end of which is connected to the conical structure and the bottom end of which is connected to the fish transfer port; the gap between the large cylinder and the grading cylinder is greater than the maximum width of the eel; from top to bottom, the gap between the spiral blade of the grading cylinder and the large cylinder gradually increases.

[0008] Preferably, the feed disc has a funnel-shaped structure, with its bottom opening located above the grading device.

[0009] Preferably, a bottom cone is coaxially connected below the grading cylinder, the bottom diameter of the bottom cone is equal to the outer diameter of the annular blade, and a corresponding fish outlet groove is provided on the large cylinder.

[0010] Preferably, the system also includes a collection device connected to the large cylinder, which includes multiple collection outlets, each of which is connected to a corresponding fish outlet trough.

[0011] Preferably, the transmission device includes a motor and a transmission shaft, with the output end of the motor connected to the transmission shaft, and the graded small cylinders coaxially connected to the transmission shaft.

[0012] Preferably, a connecting rod is rotatably connected to the drive shaft, and the connecting rod is fixedly connected to the large cylinder.

[0013] Preferably, the device also includes a water flow device, which includes a water tank, a water pump, and a water pipe. One end of the water pipe is connected to the water tank, and the other end is connected to a nozzle located above the feed disc. The water pump is connected to the water tank and the water pipe and is used to pressurize the water tank and pump the water in the water tank to the nozzle.

[0014] Preferably, the water flow device further includes a return pipe that connects the water tank to the bottom cone.

[0015] Preferably, a baffle is connected to the conical surface of the conical structure, one end of which extends to the top of the conical structure and the other end is connected to the top of the helical blade.

[0016] Preferably, the annular blade is uniformly connected with a plurality of radial guide ribs, one end of which is connected to the outer periphery of the grading small cylinder.

[0017] Preferably, the system also includes a base, the bottom of which is connected to multiple legs, and the drive shaft is rotatably connected to the base and fixedly connected to the large cylinder.

[0018] Preferably, a transmission gear set is also connected between the motor and the transmission shaft. The transmission gear set includes two meshing transmission gears, which are respectively connected to the output end of the motor and the transmission shaft.

[0019] The advantages of this invention are: 1. Multi-stage grading cylinders for step-by-step screening, resulting in high grading accuracy: Multiple grading cylinders are coaxially connected, with the gap between the large cylinder and the grading cylinders exceeding the maximum width of the eel, ensuring that all finished eels can smoothly fall from the top to the periphery of the grading cylinders. Furthermore, there is a gap between the spiral blades of the grading cylinders and the large cylinder. Eels matching the width of this gap will fall through this gap into the annular blades below for discharge, while eels that fail to pass through this gap will slide down the spiral blades to the fish inlet and be fed into the top of the next grading cylinder. The gap between the spiral blades of the grading cylinders and the large cylinder gradually increases from top to bottom, thereby achieving precise step-by-step grading of eels from small to large, with grading accuracy significantly superior to traditional equipment.

[0020] 2. Conical top and spiral blades work together to prevent accumulation and jamming: The top of the grading cylinder is a convex conical structure. After falling in, the eels naturally slide and disperse along the conical surface, avoiding accumulation in the center. The top of the spiral blades is connected to the conical structure, and the bottom is connected to the fish conveying port. As the grading cylinder rotates, the spiral blades continuously push the eels that have not passed through the gaps of this layer downwards to the fish conveying port, entering the next grading stage. This achieves automated continuous conveying and effectively solves the problems of jamming and clogging.

[0021] 3. Precise alignment of the annular blades and the fish outlet troughs ensures rapid discharge after grading: The outer diameter of the annular blades is no larger than the diameter of the large cylinder, and the gap between them is less than the minimum width of the eel. The fish outlet troughs on the circumference of the large cylinder correspond one-to-one with the annular blades. When the grading cylinder rotates, the annular blades direct all the eels that pass through the gap between the spiral blades and the large cylinder and fall onto the annular blades to the corresponding fish outlet troughs, quickly discharging them to the collection device. This prevents the graded eels from being remixed, ensuring the stability of the grading effect.

[0022] 4. Water circulation lubrication system reduces friction damage: The nozzles of the water flow device are located above the feeding disc, continuously spraying water to lubricate the surface of the eel, reducing friction damage between the eel and metal parts. At the same time, the water flow carries the eel smoothly down to the grading cylinder. The return pipe sends the water collected in the bottom cone back to the water tank, realizing water recycling and saving water.

[0023] 5. The collection device corresponds one-to-one with the fish discharge trough, making classification and collection convenient: Multiple collection outlets are connected one-to-one with the fish discharge trough. The eels separated at each stage enter the independent collection outlets, realizing classified collection, which is convenient for subsequent processing or sales, and eliminates the need for manual secondary sorting.

[0024] 6. Guided baffles to improve grading efficiency: A guide baffle is connected to the conical surface of the top conical structure of the grading cylinder. One end of the guide baffle extends to the top of the conical structure, and the other end is connected to the top of the spiral blade. When the grading cylinder rotates, it guides the eels to slide down the conical surface in an orderly manner, avoiding the eels from slipping or getting stuck on the conical surface, thus further improving grading efficiency.

[0025] 7. Radial guide ribs on the annular blades improve structural strength: The radial guide ribs evenly connected on the annular blades guide the falling eels, allowing them to exit as quickly as possible and preventing them from accumulating and pressing on the annular blades when there are too many eels. At the same time, the radial guide ribs can also improve the bending strength and rigidity of the annular blades, preventing blade deformation after long-term use and extending the service life of the device. Attached Figure Description

[0026] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the overall structure of the eel grading device of the present invention; Figure 2 This is a schematic diagram of the internal structure of the eel grading device of the present invention; Figure 3 This is a schematic diagram of the structure of the large cylindrical grading device in this invention; Figure 4 This is a schematic diagram of the collecting device in this invention; Figure 5 This is a schematic diagram of the water flow device in this invention; Figure 6 This is a schematic diagram of the transmission device in this invention; Figure 7 This is a cross-sectional view of the transmission device in this invention; In the diagram: 1-Feeding disc, 201-Large cylinder, 2011-Fish outlet trough; 202-Grading small cylinder, 2021-Annular blade, 2022-Fish inlet, 2023-Spiral blade, 2024-Baffle bar, 2025-Radial guide rib, 2026-Conical structure, 203-Bottom cone, 204-Gap, 301-Motor, 302-Drive shaft, 303-Connecting rod, 304-Drive gear, 4-Collection device, 401-Collection outlet, 501-Water tank, 502-Water pump, 503-Water pipe, 504-Return pipe, 6-Base, 601-Support leg. Detailed Implementation

[0028] Embodiments of the present invention are described in detail below, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0029] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0031] This invention provides an eel grading device to solve the technical problems of existing equipment, such as poor adaptability to eels of different sizes, easy jamming, uneven cutting, and incomplete cleaning.

[0032] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0033] Example 1 like Figures 1 to 7 As shown, this embodiment provides an eel grading device, including a feeding disc 1, a grading device, a collecting device 4, a base 6, a water flow device, and a transmission device.

[0034] like Figure 1 , 2 As shown in Figure 6, the feeding disc 1 is installed above the large cylinder 201 and has a funnel-shaped structure with a large opening at the top and a small opening at the bottom. The bottom opening is located directly above the grading device. The eels to be graded are manually poured into the feeding disc 1 in batches. Under the action of their own gravity, the eels slide down the inner wall of the funnel and enter the grading device from the bottom opening.

[0035] like Figure 2 , 3 As shown, the grading device is located below the feed disc 1 and includes a large cylinder 201 and multiple smaller grading cylinders 202. The large cylinder 201 is a fixed cylindrical shell that fits over the smaller grading cylinders 202. The multiple smaller grading cylinders 202 are coaxially connected and arranged sequentially from top to bottom. In this embodiment, there are three smaller grading cylinders 202: an upper grading cylinder, a middle grading cylinder, and a lower grading cylinder. However, this is not a limitation, and can be set to two, four, or more depending on the actual grading requirements. Each smaller grading cylinder 202 is coaxially connected to the same drive shaft and is driven to rotate synchronously by a transmission device.

[0036] The gap between the large cylinder 201 and the grading cylinder 202 is larger than the maximum width of the finished eels to ensure that all eels can pass through the gap into the grading area. The top of the grading cylinder 202 is provided with an upwardly convex conical structure 2026. The conical surface of the conical structure 2026 is smooth, and the eels naturally slide and disperse along the conical surface after falling in, avoiding accumulation in the center.

[0037] The bottom outer periphery of the grading cylinder 202 is connected to an inclined downward annular blade 2021, which rotates synchronously with the grading cylinder 202. The outer diameter of the annular blade 2021 is not greater than the inner diameter of the large cylinder 201, and the gap between them is less than the minimum width of the eel, preferably not exceeding 1 cm. Multiple fish outlet grooves 2011 are formed on the circumference of the large cylinder 201, each corresponding to one of the annular blades 2021.

[0038] The lower circumferential surface of the grading cylinder 202 is also provided with a fish transfer port 2022, which connects to the conical structure 2026 of the next-level grading cylinder 202 via the corresponding inner cavity of the grading cylinder 202. The outer circumferential surface of the grading cylinder 202 is provided with spiral blades 2023, the top end of which connects to the conical structure 2026, and the bottom end of which connects to the fish transfer port 2022. The spiral blades 2023 rotate synchronously with the grading cylinder 202, thus propelling the eels.

[0039] From top to bottom, the gap 204 between the spiral blades 2023 of the grading cylinder 202 and the large cylinder 201 gradually increases. That is, the gap 204 between the spiral blades 2023 of the uppermost grading cylinder 202 and the large cylinder 201 is the smallest, the gap is smaller in the middle layers, and the gap is largest in the bottom layer. Accordingly, eels of different sizes are separated into different layers, thus achieving the grading function.

[0040] like Figure 2 As shown, a baffle 2024 is connected to the conical surface of the top conical structure 2026 of the grading cylinder 202. One end of the baffle 2024 extends to the top of the conical structure 2026, and the other end is connected to the top of the spiral blade 2023, which serves to guide and divert the flow.

[0041] like Figure 2 As shown, a bottom cone 203 is coaxially connected below the grading cylinder 202. The bottom cone 203 is a cone-shaped structure 2026, and its bottom diameter is equal to the outer diameter of the annular blade 2021. A corresponding fish outlet trough 2011 is provided on the large cylinder 201 to collect the largest eels that did not pass through any gaps 204 in the last stage.

[0042] like Figure 2 As shown, multiple radial guide ribs 2025 are evenly connected on the annular blade 2021. One end of the radial guide rib 2025 is connected to the outer periphery of the grading cylinder 202 to guide the falling eels and discharge them as quickly as possible, preventing the eels from accumulating and being squeezed on the annular blade 2021 when there are too many of them. At the same time, the radial guide ribs 2025 can also improve the bending strength and rigidity of the annular blade 2021, prevent the blade from deforming after long-term use, and extend the service life of the device.

[0043] like Figure 4As shown, the collection device 4 is connected to the large cylinder 201 and includes multiple collection outlets 401. Each collection outlet 401 is connected to a fish outlet 2011 on the large cylinder 201 to collect eels of different sizes.

[0044] like Figure 6 , 7 As shown, the base 6 is located at the bottom of the machine, and multiple support legs 601 are connected to its bottom for supporting and fixing the machine. The transmission device includes a motor 301 and a drive shaft 302. The output end of the motor 301 is connected to the drive shaft 302, and the graded small cylinders 202 are coaxially connected to the drive shaft 302. The drive shaft 302 is rotatably connected to the base 6. A transmission gear set is also connected between the motor 301 and the drive shaft 302. The transmission gear set includes two meshing transmission gears 304, which are respectively connected to the output end of the motor 301 and the drive shaft 302.

[0045] like Figure 3 , 6 As shown, a connecting rod 303 is rotatably connected to the drive shaft 302. The connecting rod 303 is fixedly connected to the large cylinder 201. The lower end of the large cylinder 201 is fixedly connected to the base 6. When the grading small cylinder 202 rotates under the drive of the drive shaft 302, the large cylinder 201 remains fixed and does not rotate, so that the eels on the annular blades 2021 of the grading small cylinder 202 can pass smoothly through the fish outlet trough 2011 of the large cylinder 201.

[0046] like Figure 4 As shown, the water flow device includes a water tank 501, a water pump 502, a water pipe 503, and a return pipe 504. The water tank 501 stores circulating water. The water pump 502 connects the water tank 501 and the water pipe 503, pressurizing the water tank 501 and transporting the water from the tank 501 to the water pipe 503. One end of the water pipe 503 is connected to the water tank 501, and the other end is connected to a nozzle located above the feed disc 1. The return pipe 504 connects the water tank 501 to the bottom cone 203.

[0047] During operation, water pump 502 delivers water from water tank 501 to nozzles via water pipe 503. The nozzles spray water downwards to lubricate the eel's body surface and feeding channel. The water flow carries the eel into the grading device, eventually converging at the bottom cone 203. The water in the bottom cone 203 flows back to water tank 501 through return pipe 504, completing the water circulation.

[0048] The working process of the eel grading device in this embodiment is as follows: Start the motor 301 and the water pump 502. The motor 301 drives the transmission shaft 302 to rotate through the transmission gear 304. The transmission shaft 302 drives the small cylinders 202, the annular blades 2021, and the spiral blades 2023 of each stage to rotate synchronously.

[0049] The eels to be graded are manually poured into the feeding disc 1, and water is continuously sprayed from the nozzles. The eels are carried by the water flow into the conical top of the uppermost grading cylinder 202. Under the centrifugal force and the guiding action of the conical surface, the eels are evenly dispersed in all directions. Eels whose body width is smaller than the gap 204 between the spiral blades 2023 of the large cylinder 201 and the uppermost grading cylinder 202 pass through the gap and fall onto the corresponding annular blade 2021. As the annular blade 2021 rotates, it pushes them to the corresponding fish outlet 2011 and is discharged and collected through the corresponding collection outlet 401. These are the smallest size eels.

[0050] Eels with a body width greater than the gap 204 are blocked above the spiral blades 2023 on the outer periphery of the uppermost grading cylinder 202. Guided by the spiral blades 2023 and the baffles 2024, they move downward along the spiral blades 2023 and fall into the middle grading cylinder 202 through the fish transfer port 2022.

[0051] Eels falling into the intermediate grading cylinder 202 repeat the above process: eels with a body width smaller than the gap 204 between the spiral blades 2023 of the large cylinder 201 and the intermediate grading cylinder 202 pass through the gap 204 and are collected through the corresponding collection outlet 401, which is of medium size; eels with a body width larger than the gap 204 continue to fall to the bottom grading cylinder 202.

[0052] In the bottom layer of small cylindrical grading cylinders 202, eels with a body width smaller than the gap 204 are discharged and collected through the corresponding collection outlet 401; eels with a body width larger than the gap 204 eventually fall to the bottom cone 203 and are discharged and collected through the corresponding fish outlet 2011 and collection outlet 401. These are the largest size eels.

[0053] At this point, the eels were divided into several grades according to their body width from small to large, and discharged from each collection outlet 401, thus completing the grading process.

[0054] To verify the grading efficiency of this invention, live eels of the same batch but mixed sizes were used for comparative experiments, employing both traditional manual grading methods and the equipment of this invention. The experimental conditions were as follows: the manual grading group consisted of 10 skilled grading workers operating simultaneously; the equipment group consisted of one operator responsible for running the rolling eel grading machine of this invention. Each experiment lasted one hour, and was repeated three times, with the average value taken.

[0055] Experimental results show that the manual group processed an average of 85 eels per person per hour, with a total of 850 eels processed by 10 people; the equipment group processed an average of 2450 eels per hour. The grading efficiency of the equipment of this invention is 28.8 times that of a single person and 2.9 times that of 10 people combined. Calculated based on the replacement of manual labor by a single unit, this invention can replace 25-30 skilled grading workers, which is basically consistent with the theoretically estimated improvement of 20-40 times.

[0056] In terms of grading quality, the eels processed by this invention are divided into four grades according to body shape (export A / B / C / D correspond to different specifications respectively). The body shape of the eels in each grade is consistent, and the grading accuracy rate reaches 91.3%. In contrast, the accuracy rate of manual grading is greatly affected by factors such as fatigue and experience differences, and the average grading accuracy rate is only 75% to 80%.

[0057] Regarding the survival rate of eels, the survival rate of eels graded using this invention is over 96%, which is significantly better than the 85% to 90% of manual grading. This is due to the smooth mechanical grading process, which reduces repeated handling and stress damage to the eels.

[0058] Example 2 This embodiment is basically the same as Embodiment 1, except that the number of grading cylinders 202 and the number of collection outlets 401 can be adjusted according to actual grading requirements. For applications requiring finer grading, four or five grading cylinders 202 can be set, and the number of collection outlets 401 can be increased accordingly to achieve more levels of grading. For scenarios requiring coarser grading, the number can be reduced to two grading cylinders 202.

[0059] Example 3 This embodiment is basically the same as embodiment 1, except that it also includes a control cabinet. The control cabinet is electrically connected to the motor 301 and the water pump 502, and has a built-in programmable logic controller that can set the motor speed and water pump flow rate to meet the grading requirements of different batches of eels.

[0060] The eel grading device provided by this invention has a compact structure and a high degree of automation. Through multi-stage grading cylinders 202, it can accurately grade eels of different sizes, significantly improving grading efficiency and accuracy while reducing labor costs. The water circulation system effectively reduces frictional damage between the eels and metal parts, protecting product quality. This device can be widely used in eel sorting scenarios such as aquaculture, fresh food processing, and seafood sales, and has high practical value and promising prospects for promotion.

[0061] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A grading device for eels, characterized in that, It includes a feed disc (1) with an opening, a grading device and a transmission device. The grading device is located below the opening of the feed disc (1), and the transmission device is used to provide power for the rotation of the grading device. The grading device includes a large cylinder (201) and multiple grading small cylinders (202). The large cylinder (201) is sleeved on the outside of the grading small cylinders (202). The multiple grading small cylinders (202) are coaxially connected. The top of each grading small cylinder (202) is an upwardly convex conical structure (2026), and an annular blade (2021) is connected to the outer periphery of its bottom. The outer diameter of the annular blade (2021) is not greater than the inner diameter of the large cylinder (201), and the gap between them is less than the minimum width of an eel. Multiple fish outlet grooves (2011) are opened on the circumference of the large cylinder (201), and each fish outlet groove (2011) corresponds to one of the annular blades (2021). The lower circumferential surface of the grading cylinder (202) is also provided with a fish transfer port (2022), which is connected to the conical structure (2026) of the next grading cylinder (202) through the inner cavity of the corresponding grading cylinder (202); the outer circumferential surface of the grading cylinder (202) is provided with a spiral blade (2023), the top end of which is connected to the conical structure (2026) and the bottom end of which is connected to the fish transfer port (2022); the gap between the large cylinder (201) and the grading cylinder (202) is greater than the maximum width of the eel; from top to bottom, the gap between the spiral blade (2023) of the grading cylinder (202) and the large cylinder (201) gradually increases.

2. The eel grading device according to claim 1, characterized in that, The feed disc (1) has a funnel-shaped structure, with its bottom opening located above the grading device.

3. The eel grading device according to claim 1, characterized in that, The bottom cone (203) is coaxially connected below the grading small cylinder (202). The bottom diameter of the bottom cone (203) is equal to the outer diameter of the annular blade (2021), and a corresponding fish outlet trough (2011) is opened on the large cylinder (201).

4. The eel grading device according to claim 1, characterized in that, It also includes a collection device (4), which is connected to the large cylinder (201) and includes multiple collection outlets (401), which are connected one-to-one with the fish outlet trough (2011).

5. The eel grading device according to claim 1, characterized in that, The transmission device includes a motor (301) and a transmission shaft (302). The output end of the motor (301) is connected to the transmission shaft (302), and the graded small cylinders (202) are coaxially connected to the transmission shaft (302).

6. The eel grading device according to claim 5, characterized in that, A connecting rod (303) is rotatably connected to the drive shaft (302), and the connecting rod (303) is fixedly connected to the large cylinder (201).

7. The eel grading device according to claim 1, characterized in that, It also includes a water flow device, which includes a water tank (501), a water pump (502) and a water pipe (503). One end of the water pipe (503) is connected to the water tank (501), and the other end is connected to a nozzle. The nozzle is located above the feed disc (1). The water pump (502) is connected to the water tank (501) and the water pipe (503) and is used to pressurize the water tank (501) and pump the water pump (502) in the water tank (501) to the nozzle.

8. The eel grading device according to claim 7, characterized in that, The water flow device also includes a return pipe (504), which connects the water tank (501) and the bottom cone (203).

9. The eel grading device according to claim 1, characterized in that, A baffle (2024) is connected to the conical surface of the conical structure (2026). One end of the baffle (2024) extends to the top of the conical structure (2026), and the other end is connected to the top of the spiral blade (2023).

10. The eel grading device according to claim 1, characterized in that, The annular blade (2021) is provided with a plurality of radial guide ribs (2025).

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