Multi-stage grading machine and grading system

Abstract

The utility model belongs to the technical field of grader equipment, and discloses a multi-stage grader and a grading system, and the multi-stage grader comprises a machine body, a feeding mechanism, a sorting mechanism and a discharging pipe. And a plurality of sorting mechanisms and a plurality of discharging pipes are arranged. The machine body is provided with a feeding port, a negative pressure cavity is formed in the machine body, a coarse material outlet is formed in the bottom of the machine body, the negative pressure cavity communicates with the outside through the feeding port and the coarse material outlet, the feeding mechanism is arranged on the machine body, the sorting mechanisms are arranged on the machine body at intervals in the vertical direction, and the discharging pipes are arranged on the machine body at intervals in the vertical direction. And the discharge ports are communicated with the discharge ends of the sorting mechanisms in a one-to-one correspondence manner. The grading system comprises the multi-stage grading machine and a plurality of traps. By means of the arrangement, the multi-stage grading machine can obtain products of different specifications at the same time, the grading efficiency is higher, the particle size distribution of the products is better, and the product yield is higher.

Description

Technical Field

[0001] The utility model relates to the technical field of grading machine equipment, in particular to a multi-stage grading machine and a grading system. Background Art

[0002] At present, the negative electrode materials of lithium-ion batteries have very strict requirements on the particle size distribution of products. The raw materials cannot meet the product particle size requirements through a single crushing process, and they need to be graded. The existing process route is to use crushing equipment to crush the raw materials to obtain powders of a certain particle size, and then use a classifier to grade the powder to remove fine powder, narrow the particle size distribution, and thus obtain products that meet the specification requirements. However, the existing classifier can only perform classification once to obtain products of one specification. If you want to obtain products of other specifications, you need to crush and grade the raw materials again to remove fine powder. Therefore, for products with multiple specifications, multiple crushing equipment and classifiers are required, which have high investment costs and occupy a large area, while the classifier can only perform classification once, with low efficiency and low product yield. Utility Model Content

[0003] The utility model aims to provide a multi-stage classifier, which can obtain products of various specifications at the same time, has higher classification efficiency, better product particle size distribution and higher product yield.

[0004] To achieve this purpose, the utility model adopts the following technical solutions:

[0005] A multi-stage classifier, comprising:

[0006] A machine body, wherein the machine body is provided with a feed inlet, a negative pressure chamber is provided inside the machine body, a coarse material outlet is provided at the bottom of the machine body, and the negative pressure chamber is connected to the outside through the feed inlet and the coarse material outlet;

[0007] A feeding mechanism is arranged on the machine body;

[0008] A plurality of sorting mechanisms are arranged on the machine body at intervals along the vertical direction;

[0009] A plurality of discharge pipes are arranged on the machine body at intervals along the vertical direction, and are connected to the discharge ends of the plurality of sorting mechanisms in a one-to-one correspondence.

[0010] Optionally, a feed pipe penetrating in a horizontal direction is provided on the machine body, and the feed port is arranged on the feed pipe.

[0011] Optionally, the feeding mechanism includes a feeding driver and a screw rod, wherein the feeding driver is disposed on the machine body, and an output end is connected to the screw rod, and can drive the screw rod to rotate around its own axis in the feeding pipe.

[0012] Optionally, the sorting mechanism includes a sorting driver and a grading wheel. The sorting driver is arranged on the machine body, and an output end is connected to the grading wheel to drive the grading wheel to rotate.

[0013] Optionally, the sorting drive and the classifying wheel are coaxially connected, and the sorting drive can drive the classifying wheel to rotate in a horizontal direction.

[0014] Optionally, the discharge pipe and the grading wheel are coaxially arranged, the discharge end is arranged on the grading wheel, and is arranged opposite to one end of the discharge pipe facing the grading wheel with a gap therebetween.

[0015] Optionally, an air outlet is provided on an end surface of the discharge pipe at one end facing the grading wheel, and the air outlet is arranged along the circumference of the discharge pipe.

[0016] Optionally, the multi-stage classifier also includes a guide ring, which is arranged in the body and located between two adjacent sorting mechanisms. The body is tangentially provided with a plurality of air inlet pipes connected to the negative pressure chamber, and the through direction of the air inlet pipes is consistent with the tangential direction of the guide ring.

[0017] Optionally, the sorting mechanism and the discharge pipe are both provided with two, the first discharge pipe from top to bottom is used to discharge ultrafine powder, and the second discharge pipe is used to discharge fine powder;

[0018] In the vertical direction, the feeding mechanism is arranged between the two sorting mechanisms.

[0019] Another object of the utility model is to provide a grading system that can simultaneously obtain products of various specifications, has higher grading efficiency, better product particle size distribution, and higher product yield.

[0020] To achieve this purpose, the utility model adopts the following technical solutions:

[0021] A grading system comprises the above-mentioned multi-stage classifier and a plurality of collectors, wherein the plurality of collectors are respectively connected to the plurality of discharge pipes and are used for collecting powder discharged from the discharge pipes.

[0022] Beneficial effects:

[0023] The utility model provides a multi-stage classifier and a grading system. The multi-stage classifier includes a machine body, a feeding mechanism, a sorting mechanism and a discharging pipe. Among them, the sorting mechanism and the discharging pipe are each provided with a plurality, which can process raw materials at one time and produce products of different specifications. The machine body is provided with a feeding port, and a negative pressure chamber is provided inside, so that the raw materials can enter the negative pressure chamber through the feeding port for grading operation. By providing the negative pressure chamber, an airflow is formed inside the machine body, which is convenient for the flow and grading of raw materials in the machine body, and improves the grading efficiency. A coarse material outlet is provided at the bottom of the machine body, so that the coarse material after classification can be discharged to the outside of the machine body through the coarse material outlet under the action of its own weight. The feeding mechanism is arranged on the machine body, and is used for the feeding operation of the machine body, so as to realize automation and facilitate operation. Multiple sorting mechanisms are arranged on the machine body at intervals along the vertical direction. When the raw materials flow upward in the negative pressure chamber, they can be graded by multiple sorting mechanisms. Since the raw materials with small particle size and light weight will be distributed in the upper space of the negative pressure chamber, and the raw materials with large particle size and heavy weight will be distributed in the lower space of the negative pressure chamber, the upper sorting mechanism will sort out the raw materials with smaller particle size, so that the raw materials with larger particle size will be thrown out and fall. The falling raw materials will be sorted one by one by the multiple sorting mechanisms below, and then produce products of different specifications. Multiple discharge pipes are arranged on the machine body at intervals along the vertical direction, and are connected to the discharge ends of the multiple sorting mechanisms one by one, so as to discharge products of different specifications. The grading system includes the above-mentioned multi-stage classifier and multiple collectors. Through the above-mentioned arrangement, the multi-stage classifier of the present application can obtain products of multiple specifications at the same time, with higher grading efficiency, better product particle size distribution, and higher product yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the overall structure of the multi-stage classifier provided by the embodiment of the utility model;

[0025] Figure 2 It is a schematic diagram of the planar structure of the guide ring provided by the embodiment of the utility model;

[0026] Figure 3 yes Figure 1 A partial enlarged view of the middle A;

[0027] Figure 4 It is a schematic diagram of a grading system provided by an embodiment of the utility model.

[0028] In the figure:

[0029] 1. Machine body; 11. Feed inlet; 12. Negative pressure chamber; 13. Coarse material outlet; 14. Feed pipe; 15. Air inlet pipe;

[0030] 2. Feeding mechanism; 21. Feeding driver; 22. Screw rod;

[0031] 3. Sorting mechanism; 31. Sorting driver; 32. Classifying wheel;

[0032] 4. Discharge pipe; 41. Air outlet;

[0033] 5. Guide ring;

[0034] 6. Collector. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only the parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0036] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0038] In the description of this embodiment, the terms "upper", "lower", "right", etc., are based on the directions or positions shown in the drawings, and are only for the convenience of description and simplified operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0039] like Figure 1-Figure 3As shown, this embodiment provides a multi-stage classifier, which includes a machine body 1, a feeding mechanism 2, a sorting mechanism 3 and a discharge pipe 4. Among them, there are multiple sorting mechanisms 3 and discharge pipes 4. The machine body 1 is provided with a feeding port 11, and a negative pressure chamber 12 is provided inside. A coarse material outlet 13 is opened at the bottom of the machine body 1, and the negative pressure chamber 12 is connected to the outside through the feeding port 11 and the coarse material outlet 13. The feeding mechanism 2 is arranged on the machine body 1, and multiple sorting mechanisms 3 are arranged on the machine body 1 at intervals in the vertical direction. Multiple discharge pipes 4 are arranged on the machine body 1 at intervals in the vertical direction, and are connected to the discharge ends of multiple sorting mechanisms 3 one by one.

[0040] In this embodiment, the sorting mechanism 3 and the discharge pipe 4 are both provided with multiple ones, which can process the raw materials at one time and produce products of different specifications. The machine body 1 is provided with a feed port 11, and a negative pressure chamber 12 is provided inside, so that the raw materials can enter the negative pressure chamber 12 through the feed port 11 for grading. By providing the negative pressure chamber 12, an airflow is formed inside the machine body 1, which facilitates the flow and grading of the raw materials in the machine body 1 and improves the grading efficiency. A coarse material outlet 13 is provided at the bottom of the machine body 1, so that the coarse material after grading can be discharged to the outside of the machine body 1 through the coarse material outlet 13 under the action of its own weight. The feeding mechanism 2 is provided on the machine body 1, and is used for the feeding operation of the machine body 1, so as to realize automation and facilitate operation. A plurality of sorting mechanisms 3 are arranged on the machine body 1 at intervals along the vertical direction. When the raw materials flow upward in the negative pressure chamber 12, they can be graded by the plurality of sorting mechanisms 3. Since the raw materials with small particle size and light weight will be distributed in the upper space of the negative pressure chamber 12, and the raw materials with large particle size and heavy weight will be distributed in the lower space of the negative pressure chamber 12, the sorting mechanism 3 above will sort out the raw materials with smaller particle size, so that the raw materials with larger particle size will be thrown out and fall. The falling raw materials will be sorted one by one by the plurality of sorting mechanisms 3 below, and then the products of different specifications will be produced. A plurality of discharge pipes 4 are arranged on the machine body 1 at intervals along the vertical direction, and are connected to the discharge ends of the plurality of sorting mechanisms 3 one by one, so as to discharge the products of different specifications. Through the above arrangement, the multi-stage classifier of this embodiment can obtain products of multiple specifications at the same time, with higher grading efficiency, better product particle size distribution, and higher product yield.

[0041] Specifically, Figure 1 As shown, the machine body 1 is provided with a feed pipe 14 that passes through in the horizontal direction, and the feed port 11 is arranged on the feed pipe 14, so that the material can stably enter the feed pipe 14 through the feed port 11. Due to the existence of the negative pressure chamber 12, the raw material forms a stable airflow field in the machine body 1, which promotes the flow and dispersion of the raw material. Through the above arrangement, the blockage and accumulation of the raw material during the feeding process are avoided, and the continuous supply of the raw material is ensured.

[0042] More specifically, if Figure 1As shown, the feeding mechanism 2 includes a feeding driver 21 and a screw rod 22. The feeding driver 21 is arranged on the machine body 1, and the output end is connected to the screw rod 22, which can drive the screw rod 22 to rotate around its own axis in the feeding pipe 14, which not only provides power for the raw material to enter the negative pressure chamber 12, but also enables the raw material to stably enter the inside of the machine body 1 along the feeding pipe 14 under the push of the screw rod 22. In addition, due to the spiral structure of the screw rod 22 itself, the raw material can be subjected to uniform thrust when in contact with the screw rod 22, thereby avoiding the blockage and accumulation of the raw material during the feeding process. At the same time, the rotation of the screw rod 22 can also preliminarily disperse and mix the raw material, so that the raw material has reached a certain degree of uniformity before entering the negative pressure chamber 12.

[0043] More specifically, in this embodiment, the extension direction of the screw rod 22 is parallel to the through direction of the feed pipe 14 to ensure that the raw material is subjected to sufficient thrust during the feeding process to ensure the feeding effect. In addition, the feed driver 21 of this embodiment adopts a variable frequency motor, which drives the screw rod 22 to rotate. Since the variable frequency motor has the advantages of a wide speed range, smooth start-up, and high control accuracy, the operator can more conveniently control the feed speed of the raw material. In other embodiments, the feed driver 21 can also adopt a DC motor, as long as it can achieve the above-mentioned functions, and no excessive restrictions are made here.

[0044] Specifically, Figure 1 As shown, the sorting mechanism 3 includes a sorting driver 31 and a grading wheel 32. The sorting driver 31 is arranged on the body 1, and the output end is connected to the grading wheel 32, which can drive the grading wheel 32 to rotate. When the grading wheel 32 rotates under the drive of the sorting driver 31, the raw material is dispersed and subjected to a certain centrifugal force under the action of the grading wheel 32. Raw materials of different particle sizes will have different motion trajectories under the action of centrifugal force, thereby achieving classification. Raw materials with smaller particle sizes are more likely to pass through the gap of the grading wheel 32 and then be discharged through the discharging end, while raw materials with larger particle sizes are thrown out by the grading wheel 32. In addition, the sorting driver 31 of this embodiment adopts a variable frequency motor, and the grading wheel 32 is driven by the variable frequency motor to rotate. Since the variable frequency motor has the advantages of a wide speed range, smooth start-up, and high control accuracy, the operator can more conveniently control the rotation speed of the grading wheel 32. In other embodiments, the sorting driver 31 can also adopt a DC motor, as long as the above-mentioned functions can be achieved, and no excessive restrictions are made here.

[0045] More specifically, if Figure 1As shown, the sorting driver 31 and the grading wheel 32 are coaxially connected, which can ensure that the power of the sorting driver 31 is directly and efficiently transmitted to the grading wheel 32, making the whole structure more compact and easy to maintain. The sorting driver 31 can drive the grading wheel 32 to rotate in the horizontal direction, that is, the grading wheel 32 is installed horizontally and directly connected to the sorting driver 31, so that the grading wheel 32 has greater stability when working. Through the above arrangement, not only the device loss caused by vibration is reduced, but also it helps to improve the grading accuracy and ensure that the raw materials can be graded according to the predetermined particle size range. At the same time, it can also facilitate the installation and connection of the grading wheel 32 and the body 1, greatly improving the work efficiency.

[0046] More specifically, multiple sorting drivers 31 use motors of the same specifications and models, which improves versatility. After the multi-stage classifier is used for a long time, it is more convenient to purchase and replace accessories. At the same time, each sorting driver 31 is independently controlled, and then independently controls the rotation speed of multiple grading wheels 32, without interfering with each other, which is conducive to the individual adjustment of product particle size, and the adjustment of product particle size is more convenient and quick.

[0047] Specifically, Figure 1-Figure 3 As shown, the discharge pipe 4 and the grading wheel 32 are coaxially arranged, that is, the axes of the discharge pipe 4 and the grading wheel 32 coincide with each other, ensuring that the material can directly and smoothly enter the discharge pipe 4 after grading, reducing the loss and blockage risk of the material during the transmission process. The discharge end is arranged on the grading wheel 32, and is arranged opposite to the end of the discharge pipe 4 facing the grading wheel 32, so that the grading wheel 32 will not interfere with the discharge pipe 4 when rotating, avoiding affecting the grading operation.

[0048] More specifically, if Figure 1-Figure 3 As shown, an air outlet 41 is provided on the end surface of the discharge pipe 4 at one end facing the grading wheel 32, and the air outlet 41 is used to blow air toward the grading wheel 32. The air outlet 41 is arranged along the circumference of the discharge pipe 4, and then a circle of airflow is generated along the circumference of the discharge pipe 4 between the discharge pipe 4 and the grading wheel 32, that is, a discharge channel isolated from the outside is formed, so that the classified raw materials can enter the discharge pipe 4 through the discharge channel and be discharged without leaking from the gap between the discharge pipe 4 and the grading wheel 32, thereby improving the grading effect.

[0049] More specifically, in order to achieve the air outlet effect of the air outlet 41, an interlayer is provided in the discharge pipe 4, an air inlet space is formed inside the interlayer, and a through hole is opened on the outer wall of the discharge pipe 4. The air inlet space is connected to the outside through the through hole and the air outlet 41, thereby forming a passage for the air to flow. The output end of an external air outlet device (such as a fan) is connected to the through hole, so that there is enough wind at the air outlet to blow to the end face of the grading wheel 32, thereby ensuring the effective discharge of the raw materials.

[0050] Specifically, Figure 1 and Figure 2 As shown, the multi-stage classifier also includes a guide ring 5, which is arranged in the body 1 and located between two adjacent sorting mechanisms 3, and can effectively guide the airflow, so that the raw materials can be more evenly distributed and flowed in the negative pressure chamber 12. At the same time, by setting the guide ring 5, the air entering the body 1 is evenly dispersed, the raw materials are further dispersed, the raw materials are prevented from agglomerating, and the classification effect and quality are improved. The body 1 is provided with a plurality of air inlet pipes 15 connected to the negative pressure chamber 12 along the tangent direction, and the through direction of the air inlet pipe 15 is consistent with the tangent direction of the guide ring 5, so that the airflow entering the negative pressure chamber 12 forms a rotating motion, which is beneficial to the dispersion effect of the raw materials in the rotating airflow. At the same time, a plurality of guide blades are arranged along the circumferential direction of the guide ring 5, and the extension direction of the guide blades is arranged at an angle with the radial direction of the guide ring 5. When the gas enters the body 1 through the air inlet pipe 15, the flow direction of the gas is consistent with the inclination direction of the guide blades, which is conducive to the uniform dispersion of the gas and ensures the classification effect of the raw materials.

[0051] More specifically, in this embodiment, four air inlet pipes 15 are provided and evenly tangentially distributed on the outer wall of the body 1, so that air can evenly tangentially enter the negative pressure chamber 12. In other embodiments, the air inlet pipes 15 can be provided in other numbers such as 6 or 8, as long as the above-mentioned functions can be achieved, and no excessive limitation is made here.

[0052] Specifically, Figure 1 As shown, in this embodiment, there are two sorting mechanisms 3 and two discharge pipes 4. From top to bottom, the first discharge pipe 4 is used to discharge ultrafine powder, and the second discharge pipe 4 is used to discharge fine powder. In the vertical direction, the feeding mechanism 2 is arranged between the two sorting mechanisms 3. After the raw material is put into the feed port 11, it is evenly transported to the inside of the machine body 1 through the feeding mechanism 2. Under the action of the airflow in the negative pressure chamber 12, the raw material reaches the grading wheel 32 of the upper sorting mechanism 3, where the first classification is performed, and then the ultrafine powder product is discharged through the grading wheel 32 and the discharge pipe 4. The remaining raw material particles are thrown to the cylinder wall and fall down under the centrifugal force of the upper grading wheel 32. The falling material passes through the guide ring 5 (such as Figure 1 As shown, along the vertical direction, the guide ring 5 can be arranged between the feeding mechanism 2 and the lower sorting mechanism 3), the uniformly dispersed air blows and is dispersed to avoid agglomeration, and the uniformly dispersed materials continue to fall and reach the grading wheel 32 of the lower sorting mechanism 3, where they are classified for the second time, and then the fine powder products are discharged through the lower grading wheel 32 and the discharge pipe 4, and the remaining coarse powder products are thrown to the cylinder wall and fall under the centrifugal force of the lower grading wheel 32, and are discharged and collected through the coarse material outlet 13. Through the above arrangement, the multi-stage classifier of this embodiment can achieve two classifications of materials with one feeding, and produce three specifications of products, with higher classification efficiency, better product particle size distribution, and higher product yield.

[0053] like Figure 4 As shown, the present embodiment also provides a grading system, which includes the above-mentioned multi-stage classifier and multiple collectors 6. By setting the multi-stage classifier, efficient and accurate grading of raw materials can be achieved. Powders of different particle size ranges can be effectively separated after being processed by the multi-stage classifier, and discharged through different discharge pipes 4 respectively. Multiple collectors 6 are respectively connected to multiple discharge pipes 4, used to collect the powder discharged from the discharge pipes 4, and discharge the separated and purified air (the collector 6 is connected to a negative pressure fan, and the negative pressure is provided by the negative pressure fan to maintain the operation of the system. The collector 6 can be, for example, a bag dust collector, or other gas-solid separation equipment), ensuring that each particle size of powder can be specially collected and processed, avoiding the possibility of mixing and cross contamination. Through the above-mentioned settings, the grading system of the present embodiment has higher grading efficiency, better product particle size distribution, higher product yield, and can better separate and collect the classified materials and air, and then discharge the purified air into the atmosphere.

[0054] Those skilled in the art will appreciate that, in the present embodiment, the negative pressure environment in the negative pressure chamber 12 can generally be provided by a powder collecting device (the collector 6 as described above) connected to the discharge pipe 4, and the negative pressure environment in the negative pressure chamber 12 can also be achieved by other means such as exhaust equipment, which is not limited here.

[0055] In the present invention, unless otherwise specified, the sorting driver 31, the grading wheel 32, and the collector 6 are commercially available products of the prior art, and are not limited in detail as long as they can achieve the above-mentioned corresponding functions.

[0056] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the scope of protection of the present invention. It is not necessary and impossible to list all implementation methods here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the scope of protection of the claims of the present invention.

Claims

1. A multi-stage classifier, characterized in that: include: A machine body (1), wherein the machine body (1) is provided with a feed inlet (11), a negative pressure chamber (12) is provided inside the machine body, a coarse material outlet (13) is provided at the bottom of the machine body (1), and the negative pressure chamber (12) is connected to the outside through the feed inlet (11) and the coarse material outlet (13); A feeding mechanism (2) is arranged on the machine body (1); A plurality of sorting mechanisms (3) are arranged on the machine body (1) at intervals along the vertical direction; A plurality of discharge pipes (4) are arranged on the machine body (1) at intervals in the vertical direction and are connected to the discharge ends of the plurality of sorting mechanisms (3) in a one-to-one correspondence.

2. The multi-stage classifier according to claim 1, characterized in that: The machine body (1) is provided with a feed pipe (14) which penetrates in a horizontal direction, and the feed port (11) is arranged on the feed pipe (14).

3. The multi-stage classifier according to claim 2, characterized in that: The feeding mechanism (2) comprises a feeding driver (21) and a screw rod (22); the feeding driver (21) is arranged on the machine body (1), and an output end is connected to the screw rod (22), and can drive the screw rod (22) to rotate around its own axis in the feeding pipe (14).

4. The multi-stage classifier according to claim 1, characterized in that: The sorting mechanism (3) comprises a sorting driver (31) and a classifying wheel (32); the sorting driver (31) is arranged on the machine body (1), and an output end is connected to the classifying wheel (32), so as to drive the classifying wheel (32) to rotate.

5. The multi-stage classifier according to claim 4, characterized in that: The sorting driver (31) and the classifying wheel (32) are coaxially connected, and the sorting driver (31) can drive the classifying wheel (32) to rotate in a horizontal direction.

6. The multi-stage classifier according to claim 4, characterized in that: The discharge pipe (4) and the classifying wheel (32) are coaxially arranged, and the discharge end is arranged on the classifying wheel (32) and is arranged with a gap facing one end of the discharge pipe (4) facing the classifying wheel (32).

7. The multi-stage classifier according to claim 4, characterized in that: An air outlet (41) is provided on the end surface of one end of the discharge pipe (4) facing the classification wheel (32), and the air outlet (41) is arranged along the circumference of the discharge pipe (4).

8. The multi-stage classifier according to claim 1, characterized in that: The multi-stage classifier further comprises a guide ring (5), wherein the guide ring (5) is arranged in the machine body (1) and is located between two adjacent sorting mechanisms (3); the machine body (1) is provided with a plurality of air inlet pipes (15) connected to the negative pressure chamber (12) along a tangential direction, and the through direction of the air inlet pipes (15) is consistent with the tangential direction of the guide ring (5).

9. The multi-stage classifier according to claim 1, characterized in that: The sorting mechanism (3) and the discharge pipe (4) are both provided with two, the first discharge pipe (4) from top to bottom being used for discharging ultrafine powder, and the second discharge pipe (4) being used for discharging fine powder; In the vertical direction, the feeding mechanism (2) is arranged between the two sorting mechanisms (3).

10. A grading system, characterized in that It comprises the multi-stage classifier as described in any one of claims 1 to 9 and a plurality of collectors (6), wherein the plurality of collectors (6) are respectively connected to the plurality of discharge pipes (4) for collecting powder discharged from the discharge pipes (4).

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