Tobacco stem dust removal classificator

Abstract

The utility model discloses a dust removal classificator for tobacco stems, which comprises a coarse and fine screening mechanism and a long and short screening mechanism, the coarse and fine screening mechanism comprises a plurality of coarse and fine screening units, the plurality of screening units are arranged along the material conveying direction, and the horizontal positions of the screening units are gradually reduced along the material conveying direction. The long and short screening mechanism comprises a plurality of long and short screening units which are arranged in the material conveying direction, and the horizontal positions of the screening units are gradually lowered in the material conveying direction. The screening mechanism is designed to be a plurality of screening units with different horizontal positions, and a vertical fall exists between every two adjacent screening units, so that scattering of materials is facilitated in the conveying and screening process. When coarse and fine screening is carried out, the discontinuous spiral protrusions are arranged on the screening roller, the carding effect of the spiral protrusions can be achieved, obstruction to screened materials can be reduced through gaps of the discontinuous spiral protrusions, and the screening efficiency of the equipment can be improved through structural optimization in the two aspects.

Description

Technical Field

[0001] This utility model relates to the field of material sorting equipment technology, specifically to a tobacco stem dust removal and sorting machine. Background Technology

[0002] In tobacco processing, tobacco stems of different thicknesses and lengths require different processing parameters in subsequent stages. For example, thinner stems may achieve the desired expansion effect with lower pressure and a shorter time, while thicker stems require higher pressure and a longer time. When the length of the stem exceeds the appropriate range of the feed inlet of the shredder, it may clog the feed channel and affect the continuity of shredding. Shorter stems, on the other hand, can pass through the feed inlet smoothly, and the length and width of the shreds are easier to control during shredding, resulting in more uniform stem shreds that meet the requirements of subsequent cigarette manufacturing processes. Therefore, tobacco stem materials need to be screened during subsequent processing to remove materials that do not meet the processing requirements.

[0003] Many devices for measuring the thickness and sieving of tobacco stems are described in the existing technology, such as references 1 and 2.

[0004] Reference 1: Chinese patent document with publication number CN221931267U

[0005] Reference 1 describes a pre-positioned short stem removal device for a tobacco stem production line, installed at the tobacco stem feeding end. The device includes an elevator, vibrating trough, guide strips, a screening plate, a short stem discharge hopper, a conveyor plate, a long stem discharge hopper, and a conveyor. Tobacco stems are fed into the vibrating trough via the elevator belt. The screening plate separates and classifies the stems into short and long sections. Short stems are fed into a collector via the discharge hopper, while long stems are fed onto the conveyor of the tobacco stem production line via the long stem discharge hopper. The screening plate includes screening holes, separation holes, a separation surface, and a discharge trough. The discharge trough and a separation hole of equal diameter are connected directly below the screening holes on the surface of the screening plate. The screening holes are chamfered at 1×45°. The screening holes are distributed according to a sinusoidal curve. Under the action of the sinusoidal guide strips and vibrating trough, the tobacco stems move along the sinusoidal curve. The continuous separation holes and separation surface control and separate the tobacco stems to achieve a maximum spatial geometric dimension L, improving the accuracy or efficiency of separation and classification, and enhancing the quality of tobacco stem production.

[0006] Reference 2: Chinese patent document with publication number CN211359651U

[0007] Reference 2 describes a tobacco stem screening and impurity removal machine. It features 18-22 rotating rollers arranged side-by-side on a frame, each roller's cylindrical surface covered with felt. The first roller is positioned directly below the feed belt, and the tail roller has a tobacco stem outlet below it. A screening trough is positioned between the first and tail rollers, with a screen dividing it into upper and lower layers. The lower layer has a crushed material outlet at its end. By effectively separating materials, reducing the material flow on the screen, and decreasing the material thickness on the vibrating screen, this machine ensures sufficient contact between the crushed material and the screen, solving the problem of low screening efficiency in current vibrating screens. It also offers advantages such as simplified processes, space saving, reduced energy consumption, and lower investment costs. Utility Model Content

[0008] The purpose of this invention is to enrich the technical routes of tobacco stem screening equipment and provide a tobacco stem dust removal and sorting machine that is different from the existing technology.

[0009] To address the shortcomings of the aforementioned technical problems, the present invention employs the following technical solution: a tobacco stem dust removal and sorting machine, comprising a coarse and fine screening mechanism and a long and short screening mechanism;

[0010] The coarse and fine screening mechanism includes multiple coarse and fine screening units, which are arranged along the material conveying direction and the horizontal position of the screening units gradually decreases along the material conveying direction. Each screening unit includes a first drive motor, two first side plates, and a set of screening rollers passing between the two first side plates. The set of screening rollers includes multiple screening rollers arranged side by side, with a screening gap between adjacent screening rollers. The screening rollers are connected by transmission and are driven by the first drive motor to rotate synchronously in the same direction. Each screening roller includes a screening roller body and spiral protrusions on the surface of the screening roller body, and the spiral protrusions are discontinuous protrusions.

[0011] The long and short screening mechanism includes multiple long and short screening units, which are arranged along the material conveying direction. The horizontal position of the screening units gradually decreases along the material conveying direction. Each screening unit includes a second drive motor, two second side plates, and a set of screening rollers passing between the two second side plates. The set of screening rollers includes multiple screening rollers arranged side by side. A conveying roller is provided between two adjacent screening rollers. The screening rollers and the conveying rollers are connected by transmission and are driven to rotate synchronously in the same direction by the second drive motor. Each screening roller includes a screening roller body and screening grooves evenly distributed on the surface of the screening roller body. The screening groove includes a rectangular part and semicircular parts located at both ends of the rectangular part along its length. The conveying roller includes a conveying roller body and several pushing grooves evenly distributed on the surface of the conveying roller body. The pushing grooves are arranged along the length of the conveying roller body. The cross-section of the pushing grooves is V-shaped, and the several pushing grooves are evenly distributed along the circumference of the conveying roller body.

[0012] The coarse and fine screening mechanism also includes a first belt conveyor for conveying undersize material. The first belt conveyor is located below the coarse and fine screening unit and above the long and short screening mechanism. The discharge end of the first belt conveyor is provided with a hopper, which corresponds to the feed end of the long and short screening mechanism.

[0013] The long and short screening mechanism also includes a second belt conveyor for conveying undersize material, which is located below the long and short screening unit.

[0014] As a further optimization of the tobacco stem dust removal and sorting machine of this utility model: the spiral protrusion is composed of multiple spiral parts, and there is a gap between two adjacent spiral parts.

[0015] As a further optimization of the tobacco stem dust removal and sorting machine of this utility model: the gaps between the spiral sections of two adjacent screening rollers are staggered.

[0016] As a further optimization of the tobacco stem dust removal and sorting machine of this utility model: the spiral protrusions are discontinuous protrusions.

[0017] As a further optimization of the tobacco stem dust removal and sorting machine of this utility model: the coarse and fine screening unit also includes a first baffle plate, which is inclinedly arranged at the discharge end of the coarse and fine screening unit, and its upper end is fixedly connected to two first side plates.

[0018] As a further optimization of the tobacco stem dust removal and sorting machine of this utility model: the long and short screening unit also includes a second baffle plate, which is inclinedly arranged at the discharge end of the long and short screening unit, and its upper end is fixedly connected to two second side plates.

[0019] As a further optimization of the tobacco stem dust removal and sorting machine of this utility model: the tobacco stem dust removal and sorting machine is provided with a material discharge hopper at the tail end corresponding to the long and short screening mechanism.

[0020] As a further optimization of the tobacco stem dust removal and sorting machine of this utility model: the tobacco stem dust removal and sorting machine also includes a belt conveyor for conveying the material on the screen of the coarse and fine screening mechanism, and the discharge end of the belt conveyor corresponds to the material discharge hopper on the screen.

[0021] As a further optimization of the tobacco stem dust removal and sorting machine of this utility model: the screening roller body is provided with several sets of screening grooves, each set of screening grooves includes 5 screening grooves evenly distributed along the circumference of the screening roller body, and the several sets of screening grooves are distributed along the length of the screening roller body.

[0022] As a further optimization of the tobacco stem dust removal and sorting machine of this utility model: each screening unit includes at least 4 screening rollers and 3 conveying rollers.

[0023] This utility model has the following beneficial effects:

[0024] I. This utility model designs the screening mechanism as multiple screening units with different horizontal positions, and there is a vertical drop between adjacent screening units, which is more conducive to the dispersion of materials during the conveying and screening process.

[0025] Second, when performing coarse and fine screening, this utility model sets discontinuous spiral protrusions on the screening roller. This not only gives full play to the combing effect of the spiral protrusions, but also reduces the obstruction to the screening material through the gaps between the discontinuous spiral protrusions. Through the above two structural optimizations, the screening efficiency of the equipment can be improved.

[0026] Third, in the process of screening materials of different lengths, this utility model sets the screening roller and the conveying roller at intervals, which enables the separation of materials of different lengths during the conveying process. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the external structure of the dust removal and cleaning machine;

[0028] Figure 2 This is a schematic diagram of the internal structure of a dust removal and cleaning machine;

[0029] Figure 3 This is a schematic diagram of the coarse and fine screening unit (Form 1);

[0030] Figure 4 This is a schematic diagram of the coarse and fine screening unit (Form 2);

[0031] Figure 5 This is a schematic diagram of the structure of the screen roller assembly in the long and short screening unit;

[0032] Figure 6 for Figure 5 A magnified view of a portion of point A in the middle;

[0033] Figure 7 for Figure 5 A magnified view of a portion of point B in the middle;

[0034] Marked in the image:

[0035] 1A. Coarse and fine screening unit;

[0036] 101A, First drive motor;

[0037] 102A, First side plate;

[0038] 103A, Screening roller;

[0039] 1031A, Screening roller body;

[0040] 1032A, spiral protrusion;

[0041] 104A, First baffle plate;

[0042] 1B. Long and short screening units;

[0043] 101B, Second drive motor;

[0044] 102B, Second side panel;

[0045] 103B, Screening roller;

[0046] 1031B, Screening roller body;

[0047] 1032B, Screening trough;

[0048] 104B, feed roller;

[0049] 1041B, Feeding roller body;

[0050] 1042B, Pushing chute;

[0051] 2. First belt conveyor;

[0052] 3. Second belt conveyor;

[0053] 4. Discharge hopper;

[0054] 5. Chassis;

[0055] 6. Dust collector. Detailed Implementation

[0056] To better understand this utility model, the following embodiments further illustrate the content of this utility model, but the content of this utility model is not limited to the following embodiments.

[0057] like Figure 1 and 2 As shown: a tobacco stem dust collector and fine separator, including a casing, a coarse and fine screening mechanism, and a long and short screening mechanism.

[0058] The coarse and fine screening mechanism includes multiple coarse and fine screening units 1A, which are arranged along the material conveying direction. The horizontal position of the screening units 1A gradually decreases along the material conveying direction. Each screening unit 1A includes a first drive motor 101A, two first side plates 102A, and a set of screening rollers passing between the two first side plates 102A. The set of screening rollers includes multiple screening rollers 103A arranged side by side. There is a screening gap between two adjacent screening rollers 103A. The screening rollers 103A are connected by transmission and are driven to rotate synchronously in the same direction by the first drive motor 101A. Each screening roller 103A includes a screening roller body 1031A and a spiral protrusion 1032A provided on the surface of the screening roller body 1031A. The spiral protrusion 1032A is a discontinuous protrusion.

[0059] Multiple screening units 1A are arranged along the material conveying direction, forming a continuous screening process. As the material is conveyed between different screening units 1A, it undergoes multiple screenings, enabling more thorough separation of materials of different sizes.

[0060] The horizontal position of multiple screening units 1A gradually decreases along the material conveying direction, allowing the material to fall naturally under gravity as it moves from one screening unit 1A to the next. This multiple drops help to break up tangled materials. For example, during the conveying of tobacco stems, the materials may become tangled due to storage or transportation reasons. As these materials fall, they are more easily dispersed by gravity and impact, facilitating subsequent screening operations.

[0061] The vertical distance between two adjacent screening units should be 5-10cm. If the distance is too small, the material drop will be insufficient, making it difficult to fully disperse the aggregated material. If the distance is too large, it will increase the overall height of the equipment, occupy more space, and be detrimental to the installation and layout of the equipment.

[0062] The screening unit 1A includes a first drive motor 101A, two first side plates 102A, and a screen roller assembly passing between the two first side plates 102A. The screen roller assembly includes multiple screening rollers 103A arranged side by side, with a screening gap between adjacent screening rollers 103A. The screening rollers 103A are connected by transmission and are driven to rotate synchronously in the same direction by the first drive motor 101A.

[0063] The screen roller assembly consists of multiple screening rollers 103A arranged side by side, with screening gaps between adjacent screening rollers 103A. These screening gaps are key components for material screening. The material is conveyed forward by the rotation of the screening rollers 103A. Simultaneously, depending on the fineness of the material, finer materials can pass through the screening gaps and fall into the under-screen space, while coarser materials remain on the screen surface and continue to be conveyed forward.

[0064] The screening roller 103A includes a screening roller body 1031A and a spiral protrusion 1032A disposed on the surface of the screening roller body 1031A, wherein the spiral protrusion 1032A is a discontinuous protrusion. A discontinuous protrusion means that the protrusion is spiral in shape as a whole, but is not a continuous protrusion and has an interval.

[0065] like Figure 3 and Figure 4 As shown, the spiral protrusion 1032A has two specific structural forms:

[0066] The first structural form: The spiral protrusion 1032A consists of multiple spiral sections with gaps between adjacent spiral sections. This design not only utilizes the combing effect of the spiral protrusions but also reduces obstruction to the screened material through the gaps. The staggered gaps between the spiral sections of adjacent screen rollers further improve the screening effect. When material is conveyed on the screen surface, the spiral sections and gaps of different screen rollers work together to form a complex screening mechanism that can more accurately separate materials of different coarseness. For example, fine materials can more easily fall into the under-screen space through the staggered gaps, while coarse materials continue to be conveyed forward by the propulsion of the spiral sections.

[0067] The second structural form: the spiral protrusions 1032A are discontinuous. This structural form can also play a certain role in sorting materials during the conveying process. At the same time, because the protrusions are discontinuous, they have less impact on the screen gap. The protrusions can increase the friction between the screen roller and the material to a certain extent, making the material conveying on the screen surface more stable and less prone to slippage.

[0068] The end of the screening roller 103A is equipped with a transmission gear. Multiple screening rollers 103A in the same screening unit 1A are connected by chain drive, and the first drive motor 101A is driven by one of the screening rollers 103A. This transmission method has the advantages of high transmission efficiency and high reliability. Chain drive ensures that the rotation speed of each screening roller is consistent, thereby ensuring smooth material conveying on the screen surface. The drive motor is driven by one of the screening rollers and serves as the power source for the entire screening unit. The performance of the drive motor directly affects the screening efficiency and stability of the equipment. Selecting a drive motor with appropriate power can meet the needs of different material processing volumes, and the conveying speed of the material on the screen surface can be controlled by adjusting the motor speed to achieve the best screening effect.

[0069] The screening unit 1A also includes a first baffle plate 104A, which is inclinedly disposed at the discharge end of the screening unit 1A, and its upper end is fixedly connected to two first side plates 102A. The first baffle plate 104A forms an angle of 70-80° with the horizontal direction. The baffle plate can prevent material from entering the under-screen space through the vertical gap between two adjacent screening units 1A when falling. When material falls from one screening unit 1A to another screening unit 1A, it may splash in all directions due to gravity and inertia. The presence of the first baffle plate 104A can guide the falling direction of the material, so that it falls accurately on the screen surface of the next screening unit 1A, avoiding material waste and interference with the under-screen space.

[0070] The sorting conveyor also includes a first belt conveyor 2 for conveying undersize material, which is located below the screening unit 1A. When fine material falls into the undersize space through the gap between the screening rollers, the belt conveyor can promptly transport this material to a designated location for further processing or storage. Belt conveyors have advantages such as large conveying capacity, long conveying distance, and stable operation. They can be flexibly laid out and adjusted according to actual production needs, adapting to different working environments. In the spiral sorting conveyor, the combined use of the belt conveyor and the screening unit achieves continuous screening and conveying of materials, improving production efficiency. The operating speed of the belt conveyor can be matched with the working rhythm of the screening unit, ensuring that undersize material is conveyed away promptly and preventing material accumulation in the undersize space. Simultaneously, the conveying direction and position of the belt conveyor can be set according to the requirements of the production process, so as to accurately convey the undersize material to the next processing stage or storage area.

[0071] The first belt conveyor 2 is located above the long and short screening mechanism 1B. The discharge end of the first belt conveyor 2 is equipped with a hopper, which corresponds to the feed end of the long and short screening mechanism. The undersize material after being screened by the coarse and fine screening mechanism, that is, the fine material, is transported to the long and short screening mechanism via the first belt conveyor 2 for further screening of materials of different lengths.

[0072] like Figure 5-7 As shown, the long and short screening mechanism includes multiple long and short screening units 1B, which are arranged along the material conveying direction. The horizontal position of the screening units 1B gradually decreases along the material conveying direction. Each screening unit 1B includes a second drive motor 101B, two second side plates 102B, and a set of screening rollers passing between the two second side plates 102B. The set of screening rollers includes multiple screening rollers 103B arranged side by side. A conveying roller 104B is provided between two adjacent screening rollers 103B. The screening rollers 103B and the conveying roller 104B are connected by a transmission and are driven by the second drive motor 101B to perform the same... The material conveying roller 104B rotates in the same direction. It includes a material conveying roller body 1031B and a material conveying groove 1032B evenly distributed on the surface of the material conveying roller body 1031B. The material conveying groove 1032B includes a rectangular part and semi-circular parts located at both ends of the rectangular part along its length. The material conveying roller 104B includes a material conveying roller body 1041B and a plurality of material pushing grooves 1042B evenly distributed on the surface of the material conveying roller body 1041B. The material pushing grooves 1042B are arranged along the length direction of the material conveying roller body 1041B. The cross-section of the material pushing grooves 1042B is V-shaped. The plurality of material pushing grooves 1042B are evenly distributed along the circumferential direction of the material conveying roller body 1041B.

[0073] Multiple screening units 1B are arranged along the material conveying direction and their horizontal positions gradually decrease, resulting in multiple vertical drops in the material during conveying. This design helps to break up potentially intertwined long and short bars, increasing the material's looseness and thus facilitating subsequent screening. During conveying, the bars may become entangled due to storage or transportation reasons; multiple drops allow the bars to separate under the influence of gravity and impact, improving the accuracy and efficiency of screening.

[0074] The vertical distance between two adjacent screening units 1B is 5-10cm. This distance range ensures that the material has sufficient drop to achieve the dispersion effect, while preventing the overall height of the conveyor from being too high, thus facilitating the installation, operation, and maintenance of the equipment.

[0075] The screening unit 1B includes a second drive motor 101B, two second side plates 102B, and a screen roller assembly passing between the two second side plates 102B. The screen roller assembly includes multiple screen rollers 103B arranged side by side, with a conveyor roller 104B positioned between adjacent screen rollers 103B. The screen rollers 103B and the conveyor rollers 104B are connected by a transmission mechanism and are driven to rotate synchronously in the same direction by the second drive motor 101B. This synchronous rotation ensures stable material conveying on the screen surface and avoids material accumulation or blockage due to inconsistent rotation speeds.

[0076] The screening roller 103B includes a screening roller body 1031B and screening grooves 1032B evenly distributed on the surface of the screening roller body 1031B. Each screening groove 1032B includes a rectangular portion and semicircular portions at both ends along the length of the rectangular portion. This shape of the screening groove 1032B better accommodates the shapes of long and short bars, improving the screening effect. When material is conveyed on the screening roller 103B, short bars that meet the size requirements of the screening groove can fall into the screening groove, thereby achieving the separation of long and short bars. Specifically, the screening roller body 1031B of the screening roller 103B is provided with several sets of screening grooves. Each set of screening grooves includes five screening grooves 1032B evenly distributed along the circumference of the screening roller body 1031B, and these sets of screening grooves are distributed along the length of the screening roller body 1031B.

[0077] The conveying roller 104B includes a conveying roller body 1041B and several pushing grooves 1042B evenly distributed on the surface of the conveying roller body 1041B. The pushing grooves 1042B are arranged along the length of the conveying roller body 1041B, and the cross-section of the pushing grooves 1042B is V-shaped. The pushing grooves 1042B are evenly distributed along the circumference of the conveying roller body 1041B. The function of the pushing grooves 1042B is to push the material forward on the screen surface, ensuring that the material can pass smoothly through the screening unit. The V-shaped pushing groove design of the pushing grooves 1042B can better fix and push the material, preventing the material from slipping or rolling unstably during the conveying process.

[0078] The screening unit 1B also includes a second baffle plate 105B, which is inclinedly disposed at the discharge end of the screening unit 1B, and its upper end is fixedly connected to two second side plates 102B. The second baffle plate 105B forms an angle of 70-80° with the horizontal direction. When material falls from one screening unit to another, the second baffle plate 105B can guide the falling direction of the material, avoid material splashing or deviating from the conveying path, and ensure that the material accurately falls on the screen surface of the next screening unit, thereby improving the continuity and stability of screening.

[0079] The screening unit includes at least four screening rollers 103B and three conveying rollers 104B. Both the screening rollers 103B and the conveying rollers 104B have transmission gears at their ends. The screening rollers 103B and conveying rollers 104B within the same screening unit 1B are connected by a chain drive. A second drive motor 101B is connected to one of the screening rollers 103B or conveying rollers 104B. Chain drive has the advantages of high transmission efficiency and high reliability, ensuring synchronous rotation of the screening rollers and conveying rollers. The drive motor, connected to one of the screening rollers or conveying rollers, provides power to the entire screening unit. The performance of the drive motor directly affects the screening efficiency and stability of the equipment; selecting a drive motor with appropriate power can meet the needs of different material processing volumes.

[0080] The long and short screening mechanism also includes a second belt conveyor 3 for conveying undersize material, which is located below the screening unit 1B. The second belt conveyor 3, positioned below the screening unit 1B, is used to convey short bar material undersize. After the short bar material falls into the undersize space through the screening trough between the screening rollers, the belt conveyor can promptly transport this material to a designated location for further processing or storage. The belt conveyor has advantages such as large conveying capacity, long conveying distance, and stable operation. It can be flexibly laid out and adjusted according to actual production needs to adapt to different working environments. The operating speed of the belt conveyor can be matched with the working rhythm of the screening unit, ensuring that the undersize material is conveyed away in a timely manner and preventing material accumulation in the undersize space. Simultaneously, the conveying direction and position of the belt conveyor can be set according to the requirements of the production process to accurately transport the undersize material to the next processing stage or storage area.

[0081] The casing 5 is equipped with a discharge hopper 4 for the over-screen material at the tail end corresponding to the long and short screening mechanisms. The tobacco stem dust collector also includes a belt conveyor for conveying the over-screen material from the coarse and fine screening mechanisms, with the discharge end of the belt conveyor corresponding to the discharge hopper 4. The over-screen material from both the coarse and fine screening mechanisms and the long and short screening mechanisms is discharged through this discharge hopper 4.

[0082] A dust collector 6 is installed on the top of the casing 5. During the screening process, the dust attached to the material is lifted up and then sucked away by the dust collector 6 with the exhaust function, thus achieving the dust removal effect.

[0083] The specific embodiments of this utility model have been described above. It should be understood that this utility model is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the substantive content of this utility model.

Claims

1. A tobacco stem dust removal and refining machine, characterized in that: This includes the machine casing, as well as coarse and fine screening mechanisms and long and short screening mechanisms; The coarse and fine screening mechanism includes multiple coarse and fine screening units (1A), which are arranged along the material conveying direction. The horizontal position of the screening units (1A) gradually decreases along the material conveying direction. Each screening unit (1A) includes a first drive motor (101A), two first side plates (102A), and a set of screening rollers passing between the two first side plates (102A). The set of screening rollers includes multiple screening rollers (103A) arranged side by side. There is a screening gap between two adjacent screening rollers (103A). The screening rollers (103A) are connected by transmission and are driven to rotate synchronously in the same direction by the first drive motor (101A). Each screening roller (103A) includes a screening roller body (1031A) and a spiral protrusion (1032A) on the surface of the screening roller body (1031A). The spiral protrusion (1032A) is a non-continuous protrusion. The long and short screening mechanism includes multiple long and short screening units (1B), which are arranged along the material conveying direction. The horizontal position of the screening units (1B) gradually decreases along the material conveying direction. Each screening unit (1B) includes a second drive motor (101B), two second side plates (102B), and a set of screening rollers passing between the two second side plates (102B). The set of screening rollers includes multiple screening rollers (103B) arranged side by side. A conveying roller (104B) is provided between two adjacent screening rollers (103B). The screening rollers (103B) and the conveying rollers (104B) are connected by a transmission and are driven synchronously by the second drive motor (101B). The material conveying roller (103B) rotates in the direction of rotation. It includes a material conveying roller body (1031B) and a material conveying groove (1032B) evenly distributed on the surface of the material conveying roller body (1031B). The material conveying groove (1032B) includes a rectangular part and semi-circular parts located at both ends of the rectangular part in the length direction. The material conveying roller (104B) includes a material conveying roller body (1041B) and a plurality of material pushing grooves (1042B) evenly distributed on the surface of the material conveying roller body (1041B). The material pushing grooves (1042B) are arranged along the length direction of the material conveying roller body (1041B). The cross-section of the material pushing grooves (1042B) is V-shaped. The plurality of material pushing grooves (1042B) are evenly distributed along the circumferential direction of the material conveying roller body (1041B). The coarse and fine screening mechanism also includes a first belt conveyor (2) for conveying undersize material. The first belt conveyor (2) is located below the coarse and fine screening unit (1A) and above the long and short screening mechanism (1B). The discharge end of the first belt conveyor (2) is provided with a hopper, which corresponds to the feed end of the long and short screening mechanism. The long and short screening mechanism also includes a second belt conveyor (3) for conveying undersize material, which is located below the long and short screening unit (1B).

2. The tobacco stem dust removal and refining machine as described in claim 1, characterized in that: The spiral protrusion (1032A) is composed of multiple spiral sections, with a gap between two adjacent spiral sections.

3. The tobacco stem dust removal and refining machine as described in claim 2, characterized in that: The gaps between the spiral sections of two adjacent screening rollers (103A) are staggered.

4. The tobacco stem dust removal and refining machine as described in claim 1, characterized in that: The spiral protrusion (1032A) is a discontinuous protrusion.

5. The tobacco stem dust removal and refining machine as described in claim 1, characterized in that: The coarse and fine screening unit (1A) also includes a first baffle plate (104A), which is inclinedly disposed at the discharge end of the coarse and fine screening unit (1A), and its upper end is fixedly connected to two first side plates (102A).

6. The tobacco stem dust removal and refining machine as described in claim 1, characterized in that: The long and short screening unit (1B) also includes a second baffle plate (105B), which is inclinedly arranged at the discharge end of the long and short screening unit (1B), and its upper end is fixedly connected to two second side plates (102B).

7. The tobacco stem dust removal and refining machine as described in claim 1, characterized in that: The machine casing is equipped with a discharge hopper (4) for the material on the screen at the tail end corresponding to the long and short screening mechanisms.

8. The tobacco stem dust removal and refining machine as described in claim 7, characterized in that: The tobacco stem dust collector also includes a belt conveyor for conveying the material on the screen of the coarse and fine screening mechanism, and the discharge end of the belt conveyor corresponds to the material discharge hopper (4) on the screen.

9. The tobacco stem dust removal and refining machine as described in claim 1, characterized in that: The screening roller (103B) has several sets of screening grooves on its screening roller body (1031B). Each set of screening grooves includes five screening grooves (1032B) evenly distributed along the circumference of the screening roller body (1031B). The several sets of screening grooves are distributed along the length of the screening roller body (1031B).

10. The tobacco stem dust removal and refining machine as described in claim 1, characterized in that: Each of the screening units includes at least four screening rollers (103B) and three conveying rollers (104B).

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