A classifying screen vertical sand mill

Abstract

The present application relates to sand mill technical field, specifically to a kind of grading screening vertical sand mill, including mainframe, fixed frame is slidably installed in the inside of mainframe;Screening unit, the screening unit is installed in the inside of fixed frame, the screening unit includes fixed seat, and the top of fixed seat is fixedly provided with screening barrel;Stirring mechanism, the stirring mechanism is assembled in the inside of screening barrel, the stirring mechanism includes reversibly counter-rotating rotary cylinder one and rotary cylinder two, and the inner and outer wall of rotary cylinder one and rotary cylinder two is respectively provided with triangular push flow bar pin and cylindrical bar pin.The present application relies on rotary cylinder one, rotary cylinder two cooperation bar pin structure, eliminates grinding blind area, uniformly distributes grinding medium, reduces equipment energy consumption and improves grinding effect, drives screen and driving inclined plate to rotate by gear engagement, avoids screen wear and blockage problem, and material circulation grinding is realized by guide vane slope cooperation backflow channel, improves overall grinding efficiency and product quality.

Description

Technical Field

[0001] This invention relates to the field of sand mill technology, and in particular to a vertical sand mill for grading and screening. Background Technology

[0002] Currently, vertical sand mills are the mainstream wet grinding equipment, widely used in fields such as coatings, inks, pesticides, and new materials. They rely on the collision and shearing between the grinding media and the material to achieve the refinement and dispersion of solid particles. Most existing vertical sand mills adopt an integrated rod-pin rotor structure with a top static screen. The material enters from the bottom, flows upward through the grinding chamber, and then passes through the top screen to complete the separation of material beads before being discharged.

[0003] This type of traditional structure has obvious defects: First, there is no effective flow guiding structure around the screen, and the grinding zirconium balls easily accumulate on the screen surface with the material flow. Long-term friction causes screen wear and easily clogs the screen holes, frequently causing material blockage and ball leakage, affecting the quality of the finished product and the continuous operation of the equipment. Second, due to gravity, the zirconium balls are very likely to settle at the bottom of the cylinder, forming a grinding blind zone, which not only reduces the overall grinding efficiency, but also significantly increases the equipment's starting torque and operating energy consumption.

[0004] In addition, traditional equipment relies solely on the natural flow of fluid to achieve media circulation, resulting in turbulent flow field inside the cavity. The upward and downward flow of the zirconium balls lacks effective guidance, which can easily lead to uneven distribution of media in certain areas. Summary of the Invention

[0005] This invention provides a vertical sand mill for grading and screening, which solves the problems mentioned in the background art, such as the easy accumulation of zirconium balls on the screen surface of existing vertical sand mills, causing screen wear, material blockage and ball leakage; the zirconium balls also deposit at the bottom of the cylinder, forming a grinding blind zone, increasing the equipment's starting torque and energy consumption, and causing turbulent flow field inside the equipment and lack of guidance for zirconium ball circulation.

[0006] To solve the above-mentioned technical problems, one technical solution adopted by the present invention is: to provide a grading and screening vertical sand mill, including a main frame, wherein a fixed frame is slidably installed inside the main frame; A screening unit is installed inside a fixed frame. The screening unit includes a fixed base, and a screening barrel is fixedly installed on the top of the fixed base. A stirring mechanism is assembled inside a screening tank. The stirring mechanism includes a rotating cylinder 1 and a rotating cylinder 2 that can rotate in opposite directions. The inner and outer walls of the rotating cylinder 1 and the rotating cylinder 2 are respectively provided with triangular push rod pins and cylindrical rod pins. A filter assembly is disposed inside the stirring mechanism. The filter assembly includes a rotatable rotating frame. A screen is fixedly provided on the outer wall of the rotating frame. Several driving inclined plates are evenly distributed on the outer wall of the screen.

[0007] The present invention is further configured such that a driving component is provided on the top of the main frame, the output end of the driving component is connected to the stirring mechanism for transmission, and a pushing component is provided on the top of the fixed frame, one end of the pushing component is fixedly connected to the main frame.

[0008] The present invention is further configured such that a top cover is fixedly installed on the top of the screening barrel, a guide slope is provided on the bottom inner side of the screening barrel, and a feed pipe communicating with the inside of the screening barrel is installed at the bottom of the fixed base.

[0009] The present invention is further configured such that the stirring mechanism includes a fixed shell fixedly installed inside the screening barrel, and both the first rotating cylinder and the second rotating cylinder are rotatably installed inside the fixed shell. Each of the two rotating cylinders is provided with a toothed ring on the outer wall of one end of the rotating cylinder and the second rotating cylinder inside the fixed shell. A gear set is rotatably installed inside the fixed shell, and the two toothed rings are connected in opposite directions through the gear set.

[0010] The present invention is further configured such that a main shaft is fixedly provided at the top of the rotating cylinder two, the main shaft is connected to the output end of the drive component, and a plurality of flow ports are provided through the outer wall of the rotating cylinder two near the bottom.

[0011] The present invention is further configured such that the inclined surfaces of the triangular push rod pins on the inner and outer sides of the rotating cylinders one and two are arranged in opposite directions.

[0012] The present invention is further configured such that the filter assembly includes a fixed rod fixedly connected to the bottom of the screening barrel, a support plate fixedly fixed to the outside of the fixed rod, the support plate slidingly engaging with the rotating cylinder, an inlet and several return channels extending through the bottom of the support plate, a rotating frame rotatably mounted on the top of the fixed rod, a connecting frame provided on the outer wall of the fixed rod corresponding to the top position of the rotating frame, a gear ring II provided on the top of the rotating frame, a gear II rotatably mounted inside the connecting frame and meshing with the gear ring II, and a drive gear meshing with the gear II fixedly mounted on the bottom of the main shaft.

[0013] The present invention is further configured such that the lower half of the inner wall and outer wall of the first rotating cylinder and the second rotating cylinder are each equipped with a triangular pusher pin, and the upper half of the inner wall and outer wall of the first rotating cylinder and the second rotating cylinder are each equipped with a cylindrical rod pin.

[0014] The beneficial effects of the vertical sand mill for grading and screening according to the present invention are as follows: 1. This invention achieves counter-rotation of the double-layered cylinders through the coordinated operation of internal components of the stirring mechanism. The two rotating cylinders, one and two in total, are paired with triangular propulsion rods for bidirectional flow, completely eliminating the grinding blind zone caused by zirconium ball deposition at the bottom of the cylinders. This effectively reduces equipment starting torque and operating energy consumption, while simultaneously creating a stable circulating flow field between the inner and outer layers of media, preventing localized aggregation of grinding media and resulting in a more uniform distribution of zirconium balls. During the counter-rotation of the two rotating cylinders, the triangular propulsion rods continuously lift and disturb the material and zirconium balls, extending the material grinding stroke. Combined with the impact and shearing action of the cylindrical rods, this significantly enhances the material refinement and dispersion effect, improving the uniformity of material grinding and the fineness of the finished product.

[0015] 2. The internal drive gears of the screening unit mesh with the gear ring, causing the rotating frame and screen to rotate in opposite directions. Combined with the radial thrust of the inclined plate, this continuously pushes away the zircon balls around the screen, preventing them from adhering to and rubbing against the screen. This effectively eliminates screen wear, material blockage, and ball leakage, ensuring continuous and stable equipment operation and improving the quality of the finished product. The guide slope at the bottom of the screening tank works in conjunction with the return channel of the support plate to gather and guide the returned zircon balls and incompletely ground material, allowing them to re-enter the mixing mechanism for further grinding. This ensures thorough grinding and further improves the overall grinding efficiency. Attached Figure Description

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, a detailed description is provided below in conjunction with the accompanying drawings.

[0017] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0018] Figure 1 This is a three-dimensional structural diagram of a vertical sand mill for grading and screening according to the present invention; Figure 2 This is a cross-sectional view of a vertical sand mill for grading and screening according to the present invention; Figure 3 This is a cross-sectional view of the screening unit of a vertical sand mill for grading and screening according to the present invention; Figure 4 This is a separation diagram of the screening unit of a vertical sand mill for grading and screening according to the present invention; Figure 5 This is a cross-sectional view of the filter assembly and stirring mechanism of a vertical sand mill for grading and screening according to the present invention. Figure 6 This is an enlarged view of the stirring mechanism of a vertical sand mill for grading and screening according to the present invention; Figure 7 This is an enlarged view of the filter assembly of a vertical sand mill for grading and screening according to the present invention; Figure 8 This is a separation diagram of the filter assembly of a vertical sand mill for grading and screening according to the present invention.

[0019] The components in the diagram are labeled as follows: 1. Main frame; 11. Fixed frame; 12. Pushing assembly; 2. Drive assembly; 3. Screening unit; 31. Fixed base; 32. Screening barrel; 321. Guide slope; 33. Feed pipe; 34. Top cover; 35. Stirring mechanism; 351. Rotating cylinder one; 352. Rotating cylinder two; 3521. Flow port; 353. Triangular push rod pin; 354. Columnar rod pin; 355. Fixed shell; 356. Gear ring one; 357. Gear set; 358. Main shaft; 36. Filter assembly; 361. Fixed rod; 362. Support plate; 3621. Return channel; 3622. Feed port; 363. Connecting frame; 364. Rotating frame; 3641. Screen; 3642. Drive slope; 3643. Gear ring two; 3644. Gear two; 3645. Drive gear. Detailed Implementation

[0020] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," and "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the indicated position or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In addition, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or a transmission connection; it can be a direct connection or an indirect connection through an intermediate medium; it can also refer to the internal communication of two elements or the interaction between two elements.

[0022] Please see Figure 1 - Figure 8 A vertical sand mill for grading and screening includes a main frame 1, and a fixed frame 11 is slidably installed inside the main frame 1; Screening unit 3 is installed inside fixed frame 11. Screening unit 3 includes fixed base 31, and screening barrel 32 is fixedly installed on top of fixed base 31. The stirring mechanism 35 is assembled inside the screening tank 32. The stirring mechanism 35 includes a rotating cylinder 351 and a rotating cylinder 352 that can rotate in opposite directions. The inner and outer walls of the rotating cylinder 351 and the rotating cylinder 352 are respectively provided with a triangular push rod pin 353 and a cylindrical rod pin 354. A filter assembly 36 is located inside the stirring mechanism 35. The filter assembly 36 includes a rotatable rotating frame 364, and a screen 3641 is fixedly mounted on the outer wall of the rotating frame 364. Several driving inclined plates 3642 are evenly distributed on the outer wall of the screen 3641. A driving assembly 2 is mounted on the top of the main frame 1. The output end of the driving assembly 2 is connected to the stirring mechanism 35. A pushing assembly 12 is mounted on the top of the fixed frame 11. One end of the pushing assembly 12 is fixedly connected to the main frame 1. A top cover 34 is fixedly mounted on the top of the screening barrel 32. A guide inclined surface 321 is provided on the bottom inner side of the screening barrel 32. A feed pipe 33 communicating with the inside of the screening barrel 32 is mounted on the bottom of the fixed base 31.

[0023] By adopting the above technical solution, the fixed frame 11 is slidably installed inside the main frame 1, which can drive the overall adjustment of the screening unit 3, making it suitable for disassembly and maintenance. The drive assembly 2 is connected to the stirring mechanism 35, driving the rotating cylinder 1 351 and rotating cylinder 2 352 to rotate in opposite directions, and with the triangular pusher pin 353 and the cylindrical rod pin 354, bidirectional push and efficient grinding are achieved. The rotating frame 364 of the filter assembly 36 drives the screen 3641 and the drive inclined plate 3642 to rotate, which can actively push away the grinding media to prevent clogging and wear. The guide inclined surface 321 of the screening barrel 32, together with the feed pipe 33, can stably guide the material and media circulation, ensuring continuous grinding.

[0024] The stirring mechanism 35 also includes a fixed shell 355 fixedly installed inside the screening tank 32. Both rotating cylinder 1 351 and rotating cylinder 2 352 are rotatably installed inside the fixed shell 355. One end of rotating cylinder 1 351 and rotating cylinder 2 352 located inside the fixed shell 355 is provided with a gear ring 356. A gear set 357 is rotatably installed inside the fixed shell 355, and the two gear rings 356 are connected in opposite directions via the gear set 357. A main shaft 358 is fixedly installed at the top of rotating cylinder 2 352, and the main shaft 358 is connected to the output end of the drive assembly 2. Several flow ports 3521 are provided through the outer wall of rotating cylinder 2 352 near the bottom. The inclined surfaces of the triangular push rod pins 353 on the inner and outer sides of rotating cylinders 1 351 and 2 352 are oriented in opposite directions. The lower half of the inner and outer walls of rotating cylinder 1 351 and rotating cylinder 2 352 are equipped with triangular push rod pins 353, and the upper half of the inner and outer walls of rotating cylinder 1 351 and rotating cylinder 2 352 are equipped with cylindrical rod pins 354.

[0025] By adopting the above technical solution, the drive assembly 2 drives the rotating cylinder 352 to rotate via the main shaft 358. This, in conjunction with the gear set 357 and two gear rings 356 inside the fixed housing 355, causes the rotating cylinder 351 and the rotating cylinder 352 to rotate stably in opposite directions. The flow port 3521 of the rotating cylinder 352 allows materials and grinding media to flow outwards, achieving circulation between the inner and outer cavities. The upper and lower sections of the cylinder are respectively equipped with cylindrical rod pins 354 and triangular propulsion rod pins 353, with the inner and outer triangular propulsion rod pins 353 arranged at opposite angles to form bidirectional propulsion, uniformly stirring the media and enhancing the material grinding effect.

[0026] The filter assembly 36 includes a fixed rod 361 whose bottom is fixedly connected to the screening barrel 32. A support plate 362 is fixed to the outside of the fixed rod 361. The support plate 362 is slidably engaged with the rotating cylinder 351. The bottom of the support plate 362 is provided with a feed inlet 3622 and several return channels 3621. A rotating frame 364 is rotatably installed on the top of the fixed rod 361. A connecting frame 363 is provided on the outer wall of the fixed rod 361 corresponding to the top position of the rotating frame 364. A gear ring 3643 is provided on the top of the rotating frame 364. A gear 3644 is rotatably installed inside the connecting frame 363 and meshes with the gear ring 3643. A drive gear 3645 is fixedly installed at the bottom of the main shaft 358 and meshes with the gear 3644.

[0027] By adopting the above technical solution, the fixing rod 361 is fixed inside the screening barrel 32, which can stabilize the support plate 362 and the connecting frame 363. The support plate 362 and the rotating drum 351 slide together to ensure smooth rotation of the drum. The feed inlet 3622 and the return channel 3621 of the support plate 362 are responsible for material feeding and media return, respectively, to achieve circulating grinding. The drive gear 3645 of the main shaft 358 meshes with the gear 3644, and together with the gear ring 3643, drives the rotating frame 364 to rotate. Screening operation can be completed without additional power, and the structure has strong linkage.

[0028] Working principle and usage process of this invention: During operation, the material to be ground is conveyed through the feed pipe 33 and fed into the mixing chamber formed by the first rotating cylinder 351 and the second rotating cylinder 352 through the feed port 3622 of the support plate 362. The drive assembly 2 is started, and the output torque of the drive assembly 2 drives the main shaft 358 to rotate as a whole. The main shaft 358 synchronously drives the second rotating cylinder 352 to rotate in one direction. The gear ring 356 at the bottom of the second rotating cylinder 352 rotates synchronously, and transmits power through the gear set 357, driving the gear ring 356 at the end of the first rotating cylinder 351 to rotate in the opposite direction, ultimately realizing the continuous counter-rotation of the first rotating cylinder 351 and the second rotating cylinder 352.

[0029] When the rotating drum 351 rotates clockwise, the triangular propulsion pins 353 mounted on the lower half of its inner wall rotate synchronously. Relying on the upward-facing inclined surface, they continuously stir the zirconium balls and materials deposited at the bottom of the drum. The inclined surface generates an upward axial thrust, which lifts the medium upward step by step, completely eliminating the dead corner of the beads at the bottom of the drum and reducing the starting load of the equipment. The upward-flowing material contacts the zirconium balls. The triangular propulsion pins 353 on the inner wall of the rotating drum 352 rotates in the opposite direction. The triangular propulsion pins 353 rotate in the opposite direction and form a lateral impact on the upward mixed fluid. At the same time, the inclined surface pushes the material and zirconium balls to move upward continuously, extending the grinding stroke of the material and improving the grinding uniformity.

[0030] The material and zirconium balls continue to rise to the flow port 3521 at the bottom of the outer wall of the rotating cylinder 352, and flow outward through the flow port 3521, entering the outer annular cavity between the rotating cylinder and the inner wall of the screening barrel 32. Inside the outer annular cavity, the triangular pusher pins 353 arranged outward on the lower half of the outer wall of the rotating cylinder 352 rotate synchronously, relying on the downward inclined surface to apply a downward pushing force to the mixing medium, guiding the zirconium balls back to the bottom of the equipment; the triangular pusher pins 353 on the outer wall of the rotating cylinder 351 rotating in the opposite direction below again create a reverse disturbance to the downward medium, and with the secondary downward guidance of the inclined surface, the bidirectional pusher structure creates a stable inner and outer layer circulating flow field, the medium distribution is more uniform, and local zirconium balls are avoided from clustering.

[0031] The zirconia balls flowing downwards, along with a small amount of incompletely ground material, fall to the bottom of the screening barrel 32. The guide slope 321 on the inner bottom of the screening barrel 32 gathers and guides the medium. The gathered mixture flows along the guide slope 321, passes through the return channel 3621 on the support plate 362, and returns to the stirring mechanism 35 to participate in the circulating grinding again, ensuring that the material is fully ground and significantly improving the fineness of the finished product. The cylindrical pins 354 arranged in the upper half of the rotating cylinder 1 351 and rotating cylinder 2 352 rotate continuously with the cylinder body, constantly impacting and shearing the material in the cavity, enhancing the refining and dispersing effect.

[0032] During the continuous operation of the stirring mechanism 35, the fixed rod 361 remains stationary. The drive gear 3645 at the bottom of the main shaft 358 rotates synchronously with the main shaft 358. The drive gear 3645 meshes with and drives the second gear 3644 to rotate. The second gear 3644 further meshes with the second gear ring 3643, causing the rotating frame 364 to rotate in the opposite direction. The rotation direction of the rotating frame 364 is opposite to that of the main shaft 358 and the second rotating cylinder 352. The screen 3641 on the outer periphery of the rotating frame 364 and the drive inclined plate 3642 on the outer wall of the screen 3641 rotate synchronously with the rotating frame 364 in the opposite direction. During the rotation of the drive inclined plate 3642, it generates radial thrust by its own inclined surface, continuously pushing the zirconium balls that have moved to the periphery of the screen 3641 outward, keeping the zirconium balls away from the surface of the screen 3641. This prevents the zirconium balls from rubbing against the screen 3641 for a long time, thus avoiding wear caused by the zirconium balls. At the same time, it prevents the zirconium balls from directly adhering to the screen holes, which could cause material blockage or ball leakage. Under the pressure inside the cavity, the qualified refined material penetrates the screen 3641 and enters the hollow fixed rod 361. It is then discharged outward along the hollow channel of the fixed rod 361 to complete the discharge. The zircon balls intercepted by the screen 3641 flow back downward along the outer annular cavity and continue to circulate and grind.

[0033] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A vertical sand mill for grading and screening, characterized in that, include: The main frame (1) has a fixed frame (11) that is slidably installed inside the main frame (1). Screening unit (3), the screening unit (3) is installed inside the fixed frame (11), the screening unit (3) includes a fixed seat (31), and a screening barrel (32) is fixedly installed on the top of the fixed seat (31). A stirring mechanism (35) is assembled inside a screening tank (32). The stirring mechanism (35) includes a rotating cylinder one (351) and a rotating cylinder two (352) that can rotate in opposite directions. The inner and outer walls of the rotating cylinder one (351) and the rotating cylinder two (352) are respectively provided with triangular push rod pins (353) and cylindrical rod pins (354). The filter assembly (36) is located inside the stirring mechanism (35). The filter assembly (36) includes a rotatable rotating frame (364). A screen (3641) is fixedly provided on the outer wall of the rotating frame (364). Several driving inclined plates (3642) are evenly distributed on the outer wall of the screen (3641).

2. The vertical sand mill for grading and screening according to claim 1, characterized in that: The main frame (1) is provided with a drive component (2) at the top. The output end of the drive component (2) is connected to the stirring mechanism (35) in a transmission connection. The fixed frame (11) is provided with a push component (12) at the top. One end of the push component (12) is fixedly connected to the main frame (1).

3. The vertical sand mill for grading and screening according to claim 1, characterized in that: The top of the screening barrel (32) is fixedly fitted with a top cover (34), the bottom of the inner side of the screening barrel (32) is provided with a guide slope (321), and the bottom of the fixed seat (31) is fitted with a feed pipe (33) that communicates with the inside of the screening barrel (32).

4. A vertical sand mill for grading and screening according to claim 1, characterized in that: The stirring mechanism (35) also includes a fixed shell (355) fixedly installed inside the screening barrel (32). The rotating cylinder one (351) and the rotating cylinder two (352) are both rotatably installed inside the fixed shell (355). The outer wall of the rotating cylinder one (351) and the rotating cylinder two (352) located inside the fixed shell (355) is provided with a toothed ring one (356). A gear set (357) is rotatably installed inside the fixed shell (355). The two toothed rings one (356) are connected in reverse through the gear set (357).

5. A vertical sand mill for grading and screening according to claim 4, characterized in that: The top of the rotating cylinder (352) is fixedly provided with a main shaft (358), which is connected to the output end of the drive assembly (2). Several flow ports (3521) are opened through the outer wall of the rotating cylinder (352) near the bottom.

6. A vertical sand mill for grading and screening according to claim 5, characterized in that: The inclined surfaces of the triangular push rod pins (353) on the inner and outer sides of the rotating cylinders one (351) and two (352) are arranged in opposite directions.

7. A vertical sand mill for grading and screening according to claim 6, characterized in that: The filter assembly (36) includes a fixed rod (361) whose bottom is fixedly connected to the screening barrel (32). A support plate (362) is fixed to the outside of the fixed rod (361). The support plate (362) is slidably engaged with the rotating cylinder (351). The bottom of the support plate (362) is provided with a feed inlet (3622) and several return channels (3621). A rotating frame (364) is rotatably installed on the top of the fixed rod (361). A connecting frame (363) is provided on the outer wall of the fixed rod (361) corresponding to the top position of the rotating frame (364). A gear ring (3643) is provided on the top of the rotating frame (364). A gear two (3644) is rotatably installed inside the connecting frame (363) and meshes with the gear ring two (3643). A drive gear (3645) meshes with the gear two (3644) is fixedly provided at the bottom of the main shaft (358).

8. A vertical sand mill for grading and screening according to claim 1, characterized in that: The lower half of the inner and outer walls of the rotating cylinder 1 (351) and the rotating cylinder 2 (352) are equipped with triangular push rod pins (353), and the upper half of the inner and outer walls of the rotating cylinder 1 (351) and the rotating cylinder 2 (352) are equipped with cylindrical rod pins (354).

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