A tobacco stem fine separator and screen for classifying tobacco stems according to geometric size

Abstract

The present invention discloses a tobacco stem separator and a screen classified by geometric dimensions, the separator comprising a connecting part and a screening chamber, the connecting part having a first surface connected to a length-controlled screening hole screen plate, the screening chamber being arranged at one end of the connecting part and provided with an inlet and an outlet, the plane where the inlet is located being coplanar with the first surface, the inner wall of the screening chamber being a rotating curved surface, the inlet being an arc with a preset central angle, and the inlet being a rotating trajectory of the first end point of the busbar of the rotating curved surface around the rotating axis, the second end point of the busbar being located below the first end point, the busbar of the rotating curved surface being an arc and being coplanar with the rotating axis, the rotating axis being perpendicular to the plane where the inlet is located, and the separators being subdivided into categories a, b, and c depending on whether the rotating axis passes through the center of the screening hole or a point on the circumference, whether the radius of the busbar arc is L or L / 2, and whether its center coincides with the center of the screening hole or is on the circumference, and the accuracy of tobacco stem separation can be improved by adding a spherical crown and increasing the solid angle Ω of the rotating curved surface.

Description

Technical Field

[0001] The present invention belongs to the field of tobacco processing and relates to tobacco stem screening equipment technology, in particular to a tobacco stem fine separator and a screen that classifies tobacco stems according to geometric dimensions. Background Art

[0002] Automated processing, measurement, sorting, classification, and classification are common in the manufacturing industry. For example, in the bearing manufacturing industry, rollers can be measured online using geometric metrology. Given nominal dimensions and deviations, they can be automatically measured and sorted on the production line, with micron-level accuracy. For some apertures or outer diameters, physical principles and pneumatic technology can be employed to accurately test and sort them online. Their common characteristic is that they have standard geometric shapes. Simply put, these shapes can be accurately expressed using mathematical functions, or certain indicators have a functional relationship with certain physical quantities.

[0003] In the tobacco industry, automated sorting and classification are also common. For example, in tobacco leaf and cut tobacco, most key technologies rely on screen structures. For example, in the online automated screening, separation, and classification of redried tobacco leaf, for example, into leaf sizes smaller than 20mm, 20-40mm, and larger than 40mm square, the geometric shapes of tobacco leaf vary, making it virtually impossible for two leafs to have identical or identical geometric shapes and physical properties. Therefore, the screen structure typically uses a geometric aperture method for separation. Therefore, this type of classification cannot achieve the same precision as in the machinery manufacturing industry. Therefore, this classification is probabilistic, but it also meets tobacco processing requirements. In tobacco leaf processing, another more challenging and important separation and classification task is tobacco stems. In tobacco processing, these long stems need to be categorized by geometric length to facilitate subsequent processing. For example, using a geometric length of 20mm as the dividing line, stems larger than 20mm are classified as long stems, while stems smaller than 20mm are classified as short stems.

[0004] In the tobacco industry, tobacco stem sorting is generally accomplished on the production line using a multi-stage vibrating screen with a screen structure. The geometric shape of tobacco stems is also very complex. Similarly, it is almost impossible for two tobacco stems to have equal or identical geometric shapes and physical properties. For example, tobacco stems with the same mass (weight) are likely to have unequal geometric lengths, or tobacco stems with the same geometric length are likely to have unequal masses (weights). Therefore, there is no reliable scientific basis for sorting using this physical property. Furthermore, even with today's most advanced geometric measurement technologies, such as optical dynamic non-contact testing technology, it is difficult to accurately determine its value online, not to mention how to separate based on this value. Long tobacco stems have a certain hardness and a relatively small specific gravity (density). Therefore, in mathematical theory, they can be ideally fitted into cylinders, cuboids, or curved tubes, providing a scientific theoretical basis for further analysis and research on their processing methods. For example, in the tobacco industry, multi-stage vibrating screens are generally used for sorting using the geometric aperture method. If the vibrating screen does not exert a force on the tobacco stems in the direction of directional flow during screening on a multi-stage vibrating screen, the movement of the tobacco stems on the vibrating screen in the assembly line will be like the "Brownian motion" in physics. Therefore, it is very difficult to measure the size of the tobacco stems online in real time and to automatically separate and classify them with high accuracy. Therefore, it is difficult and very important to study the automatic length control, sorting and classification of tobacco stems.

[0005] Currently, in the tobacco processing field, the multi-stage vibrating screens used for tobacco stem screening, regardless of whether the holes are rectangular, kidney-shaped, or circular, elliptical, or crescent-shaped, and regardless of how the holes are distributed, such as a plum blossom or hexagonal arrangement, theoretically, control of stem length is achieved in one or two dimensions (unidirectional or in a plane). Obviously, in the separation and classification of tobacco stems achieved by this method, those classified as long stems either have an extremely high content of short stems, or those classified as short stems either have an extremely high content of long stems. Therefore, these separation methods are ineffective and do not meet strict process and technical requirements. The applicant believes that tobacco stem length control separation is essentially a measurement and separation based on a set standard caliper, just as the standard caliper is designed with long or round holes. Therefore, there is no sufficient scientific theoretical basis for accurately measuring tobacco stem size in either one or two dimensions. Therefore, on a vibrating screen, it is even more difficult to accurately separate and classify tobacco stems that rotate in three-dimensional space and have N degrees of freedom of movement. Clearly, traditional methods are unscientific. Therefore, to further improve the accuracy of separating and classifying tobacco stems according to a given geometric length dimension, the best approach should be to study the length-controlled separation principle in three-dimensional space. Summary of the Invention

[0006] In order to solve at least one aspect of the above problems, the present invention provides a tobacco stem separator classified by geometric size, the separator comprising a connecting portion and a screening chamber, the connecting portion having a first surface, the first surface being used to connect a screen plate, the screening chamber being provided at one end of the connecting portion, the screening chamber being provided with an inlet and an outlet, the plane where the inlet is located being coplanar with the first surface, the inner wall of the screening chamber being either a first rotational curved surface or a second rotational curved surface, wherein,

[0007] The feed port is an arc with a preset first central angle, and the feed port is a rotation trajectory of the first endpoint of the generatrix of the first rotation curved surface around the rotation axis of the first rotation curved surface, the rotation axis of the first rotation curved surface passes through the center of the feed port and is perpendicular to the plane where the feed port is located, the generatrix of the first rotation curved surface is an arc and is coplanar with the rotation axis, the center and the first endpoint of the generatrix of the first rotation curved surface are respectively the two endpoints of the feed port diameter, the central angle of the generatrix of the first rotation curved surface is a preset second central angle, the second endpoint of the generatrix of the first rotation curved surface is located below the starting point of the generatrix, and the discharge port is a line connecting the generatrix of the first rotation curved surface at the starting point and the end point of the rotation trajectory;

[0008] The feed port is an arc with a preset third central angle, and the feed port is the rotation trajectory of the first end point of the generatrix of the second rotation surface around the rotation axis of the second rotation surface, the rotation axis of the second rotation surface passes through the center of the feed port and is perpendicular to the plane where the feed port is located, the generatrix of the second rotation surface is an arc and is coplanar with the rotation axis, the center of the generatrix of the second rotation surface coincides with the center of the feed port, the central angle of the generatrix of the second rotation surface is a preset fourth central angle, the second end point of the generatrix of the second rotation surface is located below the first end point, and the discharge port is the line connecting the generatrix of the second rotation surface at the starting point and the end point of the rotation trajectory.

[0009] Preferably, the first central angle is greater than or equal to 180° and less than or equal to 270°.

[0010] Preferably, the second central angle is equal to 60°.

[0011] Preferably, it also includes a first spherical cap, the inner wall of the first spherical cap is a third rotational surface, the rotation axis of the third rotational surface is the same as the rotation axis of the first rotational surface, the generatrix of the third rotational surface is coplanar with the rotation axis, the first endpoint of the generatrix of the third rotational surface coincides with the second endpoint of the generatrix of the first rotational surface, the central angle of the generatrix of the third rotational surface is a preset fifth central angle, and the starting point and end point of the rotation trajectory of the generatrix of the third rotational surface are respectively the end point and starting point of the rotation trajectory of the generatrix of the first rotational surface.

[0012] Preferably, the fifth central angle is greater than or equal to 15° and less than or equal to 30°.

[0013] Preferably, the third central angle is greater than or equal to 180° and less than or equal to 270°.

[0014] Preferably, the fourth central angle is greater than or equal to 90° and less than or equal to 120°.

[0015] Preferably, the fourth central angle is greater than 105° and less than or equal to 120°.

[0016] Preferably, the fourth central angle is greater than or equal to 30° and less than or equal to 60°.

[0017] Preferably, the connecting portion is provided with at least one limiting hole, and the limiting hole communicates with the bottom of the connecting portion and the first surface.

[0018] On the other hand, a tobacco stem screen is provided, comprising: a screen plate, a plurality of circular screening holes are provided on the screen plate, the screening holes are connected to the upper and lower surfaces of the screen plate, and a plurality of refiners; a plurality of the refiners are arranged on the lower surface of the screen plate, and the plurality of the refiners correspond one-to-one to the plurality of the screening holes, the plurality of refiners adopt a combination of one or more of the first refiner, the second refiner and the third refiner, the first refiner, the second refiner and the third refiner all include a connecting portion and a screening cavity, the connecting portion has a first surface, the first surface is parallel to the screen plate and is fixedly connected to the lower surface of the screen plate, the screening cavity is arranged at one end of the connecting portion, the screening cavity is provided with an inlet and an outlet, and the plane where the inlet is located is coplanar with the first surface; wherein,

[0019] The inner wall of the screening chamber of the first refiner adopts a first rotating surface, the feed port is an arc with a preset first central angle, and the feed port is a rotation trajectory of the first end point of the generatrix of the first rotating surface line around the rotation axis of the first rotating surface, the rotation axis of the first rotating surface passes through the center of the feed port and is perpendicular to the plane where the feed port is located, the generatrix of the first rotating surface is an arc and is coplanar with the rotation axis, the center and the first end point of the generatrix of the first rotating surface are respectively the two end points of the feed port diameter, the central angle of the generatrix of the first rotating surface is a preset second central angle, the second end point of the generatrix of the first rotating surface is located below the starting point of the generatrix, and the discharge port is a line connecting the generatrix of the first rotating surface at the starting point and the end point of the rotation trajectory; the diameter of the feed port is equal to the diameter of the screening hole, and the rotation axis of the first rotating surface passes through the center of the screening hole;

[0020] The inner wall of the screening chamber of the second refiner adopts a second rotating surface, the feed port is an arc with a preset third central angle, and the feed port is a rotation trajectory of the first end point of the generatrix of the second rotating surface around the rotation axis of the second rotating surface, the rotation axis of the second rotating surface passes through the center of the feed port and is perpendicular to the plane where the feed port is located, the generatrix of the second rotating surface is an arc and is coplanar with the rotation axis, the center of the generatrix of the second rotating surface coincides with the center of the feed port, the central angle of the generatrix of the second rotating surface is a preset fourth central angle, the second end point of the generatrix of the second rotating surface is located below the first end point, and the discharge port is a line connecting the generatrix of the second rotating surface at the starting point and the end point of the rotation trajectory; the diameter of the feed port is equal to the diameter of the screening hole, and the rotation axis of the second rotating surface passes through the center of the screening hole;

[0021] The inner wall of the screening chamber of the third refiner adopts a fourth rotational curved surface, the feed port is an arc with a preset sixth central angle, and the feed port is a rotation trajectory of the first end point of the generatrix of the fourth rotational curved surface around the rotation axis of the fourth rotational curved surface, the rotation axis of the fourth rotational curved surface passes through the center of the feed port and is perpendicular to the plane where the feed port is located, the generatrix of the fourth rotational curved surface is an arc and is coplanar with the rotation axis, the center of the generatrix of the fourth rotational curved surface coincides with the center of the feed port, the central angle of the generatrix of the fourth rotational curved surface is a preset seventh central angle, the second end point of the generatrix of the fourth rotational curved surface is located below the first end point, the discharge port is a line connecting the generatrix of the fourth rotational curved surface at the starting point and the end point of the rotation trajectory, the radius of the feed port is equal to the diameter of the screening hole, the screening hole is tangent to the feed port at the midpoint of the feed port, and the screening hole and the feed port diameter circle are inscribed at the center of the feed port;

[0022] Preferably, the first central angle of the first fine divider is greater than or equal to 180° and less than or equal to 270°.

[0023] Preferably, the second central angle of the first fine divider is equal to 60°.

[0024] Preferably, the first divider also includes a first spherical cap, the inner wall of the first spherical cap is a third rotational surface, the rotation axis of the third rotational surface is the same as the rotation axis of the first rotational surface, the center line of the third rotational surface is coplanar with the rotation axis, the first endpoint of the center line of the third rotational surface coincides with the second endpoint of the center line of the first rotational surface, the central angle of the center line of the third rotational surface is a preset fifth central angle, and the starting point and end point of the rotation trajectory of the center line of the third rotational surface are respectively the end point and starting point of the rotation trajectory of the center line of the first rotational surface.

[0025] Preferably, the fifth central angle of the first fine divider is greater than or equal to 15° and less than or equal to 30°.

[0026] Preferably, the third central angle of the second fine divider is greater than or equal to 180° and less than or equal to 270°.

[0027] Preferably, the fourth central angle of the second fine divider is greater than or equal to 90° and less than or equal to 120°.

[0028] Preferably, the fourth central angle of the second fine divider is greater than or equal to 105° and less than or equal to 120°.

[0029] Preferably, the fourth central angle of the second fine divider is greater than or equal to 30° and less than or equal to 60°.

[0030] Preferably, the sixth central angle of the third fine divider is greater than or equal to 180° and less than or equal to 270°.

[0031] Preferably, the seventh central angle of the third fine divider is greater than or equal to 90 degrees and less than or equal to 120 degrees.

[0032] Preferably, the seventh central angle of the third fine divider is greater than 105° and less than or equal to 120°.

[0033] Preferably, the connecting portion is provided with at least one limiting hole, and the limiting hole communicates with the bottom of the connecting portion and the first surface.

[0034] Preferably, it also includes two guard plates and multiple cosine guide plates, the two guard plates are respectively arranged at the two ends of the screen plate, the multiple cosine guide plates are evenly arranged between the two guard plates, the multiple screening holes are distributed in columns, and each column of screening holes is spaced apart from the cosine guide plates.

[0035] Preferably, the distance between the centers of any two adjacent sieve holes among the plurality of sieve holes is greater than 2 times the diameter of the sieve hole and less than 2.5 times the diameter of the sieve hole.

[0036] The tobacco stem fine separator and screen according to geometric size of the present invention have the following beneficial effects:

[0037] Key technologies and commonalities: Precise separation of tobacco stems is a difficult problem in the tobacco industry. This invention utilizes the characteristics of spatially rotating curved surfaces to accurately determine and separate tobacco stems according to the specified size L in three-dimensional space, with the specified size L serving as the dividing line under conditions of dynamic stem rotation and directional flow. This invention is significantly innovative in terms of novelty and creativity, and is scientific and reliable in terms of theory. Because the physical properties, vibrating screening performance, and process requirements for tobacco stem classification vary under different conditions, this technical solution proposes seven methods, namely, Class A, Class B, and Class C, with different separation effects. These methods can be combined to meet different process requirements. To achieve higher accuracy in tobacco stem separation and classification, a design technique for increasing the solid angle Ω on this basis is proposed. The spherical crown design can prevent some tobacco stems from falling into the short stem category from different directions in three-dimensional space, which is particularly important in the tobacco stem feeding section. Therefore, it is a key technology for precise separation. For multi-stage vibrating screening, a multi-specification classification method based on different tobacco stem sizes L is also proposed. These core key technologies are beneficial to the development of the tobacco industry. For example, the improvement of tobacco stem screening accuracy depends on whether single-stage vibration screening is sufficient, and whether the corresponding tobacco machinery equipment is technically optimized, which will change the equipment space occupation and cost investment; for silk making and cigarette making processes, whether to study the multi-specification classification of tobacco stem size L, etc.

[0038] Technical versatility: In the tobacco industry, this technical solution is not only targeted at the leaf beating and re-roasting process, but also at the silk-making process. For example, the new tobacco developed today has a fixed length and width of tobacco, such as 20mm, 25mm, etc. Its separation and classification is also a technical difficulty. Since the physical characteristics of new tobacco tobacco are similar to those of tobacco stems, such as having a certain hardness and a not-too-small specific gravity (density), it is a very standard rectangular parallelepiped in the mathematical model. Therefore, this technical solution can also be applied to the silk-making process. Outside the tobacco industry, all products that are sorted by the vibration screening process and can be fitted into a cylinder, rectangular parallelepiped or curved tube in the mathematical model, and have a certain hardness and a not-too-small specific gravity, can be studied for their application.

[0039] Because the vibrating screening process is used to separate and sort tobacco stems, especially in large-scale redrying plants like the Hongta Group's Yuxi Cigarette Factory, with its high stem flow rate, complex stem geometry, and variable stem movement paths, achieving 100% accurate separation according to the specified size is almost impossible. This technical solution has examined this issue and studied related technologies, such as design solutions that increase the solid angle Ω. Despite this, there is a theoretical probability that long stems will be mixed with short stems, or short stems will remain among long stems, even if this probability is very small. Therefore, there is always a solution that can strike a balance between screening efficiency and screening accuracy.

[0040] At present, the general tobacco stem screening in the tobacco industry is to control the length of the separation and classification in the plane. Therefore, this technical solution has a qualitative improvement in screening efficiency and accuracy. Since in this technical solution, the spatial size separator can be processed by NC machine tools and can be installed on the vibrating screen through threads, the spatial size separator on the vibrating screen can be replaced in order to achieve the best process effect. In order to solve the problem of manufacturing costs, the manufacturing mold of the spatial size separator can be designed according to this technical solution to obtain a stamped thin leather part of the spatial size separator, which only needs to be spot welded to the corresponding screening hole. At the same time, for multi-stage vibrating screens, it is proposed to design spatial size separators with different control size L standards to realize the classification of tobacco stems of multiple specifications. Therefore, this technical solution improves the performance of the vibrating screen, improves production efficiency and screening accuracy, and also provides process guarantees for silk making and cigarette making.

[0041] Significant economic and social benefits: The utilization value of tobacco stems is very high, and the key lies in separation, classification and reasonable application. With the application of this technical solution, the improvement of tobacco stem screening accuracy will undoubtedly produce greater economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] To better understand the above and other objects, features, advantages, and functions of the present invention, reference may be made to the embodiments shown in the accompanying drawings. Like reference numerals in the accompanying drawings refer to like components. Those skilled in the art should understand that the accompanying drawings are intended to schematically illustrate preferred embodiments of the present invention and have no limiting effect on the scope of the present invention. The components in the drawings are not drawn to scale.

[0043] Figure 1 A schematic structural diagram of a tobacco stem separator including a first rotating curved surface according to an embodiment of the present invention is shown (category a1);

[0044] Figure 2 Another perspective structural diagram (type a1) of a tobacco stem separator including a first rotating curved surface according to an embodiment of the present invention is shown;

[0045] Figure 3 A schematic diagram of the structure of a tobacco stem separator according to an embodiment of the present invention, including a cross-section of the first rotating curved surface through the diameter of the feed port, and a mechanical analysis diagram of tobacco stems on the rotating curved surface (category a);

[0046] Figure 4 A schematic structural diagram of a tobacco stem separator including a first spherical cap according to an embodiment of the present invention is shown (category a2);

[0047] Figure 5 Another perspective structural diagram (type a2) of the tobacco stem separator including the first spherical cap according to an embodiment of the present invention is shown;

[0048] Figure 6A schematic perspective structural diagram of a tobacco stem separator including a second rotational curved surface according to an embodiment of the present invention is shown (category b1);

[0049] Figure 7 A schematic diagram of the structure of a tobacco stem separator including a cross-section of the second rotating curved surface through the feed port diameter and a mechanical analysis diagram of tobacco stems on the rotating curved surface (category b1) according to an embodiment of the present invention is shown;

[0050] Figure 8 A schematic structural diagram of a tobacco stem separator including a second spherical cap according to an embodiment of the present invention is shown (category b2);

[0051] Figure 9 Another perspective structural diagram (type b2) of the tobacco stem separator including the second spherical cap according to an embodiment of the present invention is shown;

[0052] Figure 10 A schematic structural diagram of a tobacco stem separator including a second spherical cap and a cross-sectional view of the feed inlet diameter according to an embodiment of the present invention is shown (category b2);

[0053] Figure 11 Another structural schematic diagram (type b3) of the tobacco stem separator including a second rotating curved surface according to an embodiment of the present invention is shown;

[0054] Figure 12 A schematic perspective structural diagram of a tobacco stem separator including a second rotational curved surface according to an embodiment of the present invention is shown (category b3);

[0055] Figure 13 A schematic diagram (type b3) showing a generatrix including a second rotational curved surface of a tobacco stem separator according to an embodiment of the present invention is shown;

[0056] Figure 14 A perspective structural diagram of a type C fine separator with a tobacco stem screen according to an embodiment of the present invention is shown (type C1);

[0057] Figure 15 A schematic structural diagram of a C-type fine separator busbar with a tobacco stem screen according to an embodiment of the present invention and a mechanical analysis diagram of tobacco stems on a rotating surface (C1 type) are shown;

[0058] Figure 16 A schematic diagram of the generatrix structure of a type C fine separator with a tobacco stem screen including a third spherical cap (type C2) according to an embodiment of the present invention is shown;

[0059] Figure 17 A perspective structural diagram of a type C fine separator and a sieve plate with a tobacco stem sieve according to an embodiment of the present invention is shown;

[0060] Figure 18Another structural schematic diagram of a type C fine separator and a sieve plate with a tobacco stem sieve according to an embodiment of the present invention is shown;

[0061] Figure 19 Another perspective structural diagram (C2 type) of a C type fine separator and a sieve plate with a tobacco stem sieve according to an embodiment of the present invention is shown;

[0062] Figure 20 A schematic structural diagram of a type B2 fine separator among type B fine separators having a tobacco stem screen according to an embodiment of the present invention is shown;

[0063] Figure 21 A schematic structural diagram of a type B2 fine separator, a sieve plate, and sieve holes in a type B fine separator with a tobacco stem sieve according to an embodiment of the present invention is shown;

[0064] Figure 22 A schematic structural diagram of a tobacco stem screen according to an embodiment of the present invention is shown;

[0065] Figure 23 Another schematic structural diagram of a tobacco stem screen according to an embodiment of the present invention is shown;

[0066] Figure 24 A mechanical analysis diagram showing the deformation point and equilibrium point of a homogenized idealized tobacco stem according to the prior art is shown;

[0067] Figure 25 A mechanical equilibrium analysis diagram of a homogeneous idealized tobacco stem model with two-dimensional sieve holes according to the prior art is shown.

[0068] Reference numerals:

[0069] 1. Fine separator; 2. Screening hole; 3. Screen plate; 4. Guard plate; 5. Cosine guide plate; 6. Fastener; 11. First surface; 12. Screening cavity; 13. First spherical crown; 14. Second spherical crown; 15. Limiting hole; 16. Third spherical crown. DETAILED DESCRIPTION

[0070] The following description of exemplary embodiments of the present disclosure is made in conjunction with the accompanying drawings, including various details of the embodiments of the present disclosure to facilitate understanding. These details should be considered as merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present disclosure. Similarly, for the sake of clarity and conciseness, descriptions of well-known functions and structures are omitted in the following description.

[0071] As used herein, the term "including" and its variations represent open inclusion, i.e., "including but not limited to." Unless otherwise stated, the term "or" means "and / or." The term "based on" means "based at least in part on." The terms "an example embodiment" and "an embodiment" mean "at least one example embodiment." The term "another embodiment" means "at least one additional embodiment." The terms "first," "second," etc. may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0072] The theoretical mechanics and spatial geometry analysis for screening target length tobacco stems are as follows, considering smooth surfaces and ignoring static friction. Figure 24 As shown in the figure, assume that a homogeneous, idealized tobacco stem MN has a length of L, and its center of gravity G, the geometric center of the stem, is located at the midpoint of the line segment MN. If the fulcrum is located at point G, according to theoretical mechanics, the tobacco stem remains balanced; otherwise, it will flip and fall. Simultaneously, the Bessel point B or the Avery point A at each end of the tobacco stem MN can be calculated through mechanics and calculus, respectively. This is a key point in the study of mechanics and metrology. Assuming that two fulcrums are located at the Bessel point B or the Avery point A at each end of MN, the tobacco stem MN will undergo minimal deformation under the action of gravity, and the two end surfaces will remain parallel. Therefore, when a single fulcrum is located between the Avery point A and the end point N, the tobacco stem MN will gradually accelerate its flipping and falling.

[0073] like Figure 25As shown, when the screening (or screening hole) size value CD is L, only considering the case where the tobacco stem MN flows horizontally in the S direction on the vibrating screen plate, when the center of gravity G of the tobacco stem MN moves over the edge D of the screening hole of the screen plate, the tobacco stem MN will flip over and fall into the screening hole CD. If the endpoint M of one end of the tobacco stem approaches the edge C of the screening hole of the screen plate, the maximum length value of the tobacco stem MN can approach 2L; if the Avery point A of the tobacco stem MN and the edge D of the screening hole CD of the screen plate overlap, if the endpoint M of one end of the tobacco stem approaches the edge C of the screening hole of the screen plate, the maximum length value of the tobacco stem MN can approach 1.2679L, that is, tobacco stems with a length of 1.2679L to 2L can quickly flip over and fall into the size value. Therefore, to screen out tobacco stems with a size value CD of L while excluding those larger than L, regardless of whether the screening holes are rectangular or circular, there is no scientific basis. This is also the reason why it is difficult to achieve highly accurate length-controlled separation in a two-dimensional plane. Furthermore, this only considers the case where the tobacco stems MN flow horizontally along the S direction on the vibrating screen plate, and does not consider other spatial positions of the tobacco stems MN under the action of the vibrating screen. For example, if the endpoint M of the tobacco stem is located below the position of the edge CD of the screening hole, as long as the center of gravity G of the tobacco stem is within the vertical spatial range of the screening hole CD, theoretically, regardless of the length value L of the tobacco stem MN or its spatial state, it will likely fall into the screening hole CD. Therefore, it is difficult to achieve high accuracy in the length-controlled separation and classification of tobacco stems in either one or two dimensions.

[0074] The applicant believes that a spatial circular curved surface (or sphere) is a spatial surface of rotation with the following key features: the distance from any point on the circular curved surface (or sphere) to the center of the circle (or sphere) is equal; the normal on the tangent plane of any point on the circular curved surface (or sphere) points toward the center of the circle (or sphere), and the direction of the reaction force to the force applied to that point also points toward the center of the circle (or sphere); and the distance between any two points on the circular curved surface (or sphere), i.e., the chord length, is less than the diameter of the surface. Therefore, to improve the accuracy of tobacco stem separation and classification, the characteristics of this spatial circular curved surface (or sphere) should be utilized to study the length-controlled separation and classification theory of tobacco stems in three dimensions, which has high scientific value.

[0075] In order to at least partially solve one or more of the above-mentioned problems and other potential problems, an embodiment of the present disclosure proposes a tobacco stem separator classified by geometric dimensions, the separator comprising a connecting portion and a screening chamber, the connecting portion having a first surface, the first surface being used to connect the screen plate, the screening chamber being arranged at one end of the connecting portion, the screening chamber being provided with an inlet and an outlet, the plane where the inlet is located being coplanar with the first surface, the inner wall of the screening chamber being any one of a first rotating curved surface and a second rotating curved surface, wherein the inlet is an arc with a preset first central angle, and the inlet is a rotation trajectory of the first end point of the generatrix of the first rotating curved surface around the rotation axis of the first rotating curved surface, the rotation axis of the first rotating curved surface passes through the center of the inlet and is perpendicular to the plane where the inlet is located, the generatrix of the first rotating curved surface is an arc and is coplanar with the rotation axis, the center and the first end point of the generatrix of the first rotating curved surface are the inlet respectively. The two endpoints of the opening diameter, the central angle of the generatrix of the first rotational surface is the second central angle, the second endpoint of the generatrix of the first rotational surface is located below the starting point of the generatrix, and the discharge port is the line connecting the generatrix of the first rotational surface at the starting point and the end point of the rotation trajectory; the feed port is an arc with a preset third central angle, and the feed port is the rotation trajectory of the first endpoint of the generatrix of the second rotational surface around the rotation axis of the second rotational surface, the rotation axis of the second rotational surface passes through the center of the feed port and is perpendicular to the plane where the feed port is located, the generatrix of the second rotational surface is an arc and is coplanar with the rotation axis, the center of the generatrix of the second rotational surface coincides with the center of the feed port, the central angle of the generatrix of the second rotational surface is a preset fourth central angle, the second endpoint of the generatrix of the second rotational surface is located below the first endpoint, and the discharge port is the line connecting the generatrix of the second rotational surface at the starting point and the end point of the rotation trajectory.

[0076] Specifically, if Figure 1-Figure 2 、 Figure 4-Figure 6 As shown in FIG. 1 , the connecting portion of the separator 1 has a first surface 11 , wherein the first surface 11 is the plane at the top of the separator 1 body, the screening cavity 12 is a cavity opened at one end of the separator 1 body, and the inner wall of the screening cavity 12 is a rotating curved surface.

[0077] like Figures 1 to 3 As shown, when the inner wall of the screening cavity 12 is the first rotation curved surface S1, the inlet Lr is the arc of intersection of the first rotation curved surface S1 and the first surface 11, and the outlet Lc is the other boundary of the first rotation curved surface S1.

[0078] The feed port Lr is an arc with a preset first central angle ∠COD, and points C and D are the two endpoints of the arc of the feed port Lr. In some embodiments, the first central angle ∠COD is greater than or equal to 180°, and less than or equal to 270°. In particular, when the first central angle ∠COD is equal to 180°, that is, the straight line CD is the diameter of the center O of the feed port Lr, the feed port Lr is the rotation trajectory of the first endpoint C of the generatrix CC1 of the first rotation surface S1 around the rotation axis L of the first rotation surface S1, the rotation axis L of the first rotation surface S1 passes through the center O of the feed port Lr and is perpendicular to the plane where the feed port Lr is located (that is, the first surface 11), and the generatrix CC1 of the first rotation surface S1 is an arc and is coplanar with the rotation axis L. The center of the generatrix CC1 of the first rotation surface S1 is another intersection of the diameter of OC and the circumference of the feed port Lr. For example, in this embodiment, it is point D. The center angle of the generatrix CC1 of the first rotation surface S1 is the second center angle ∠CDC1. The second endpoint C1 of the generatrix CC1 of the first rotation surface S1 is located below the first endpoint C of the generatrix CC1. In particular, the second center angle ∠CDC1 is equal to 60°, then point C1 is the intersection of the generatrix CC1 and the rotation axis L. The first rotation surface S1 is a rotation surface formed by the generatrix CC1 rotating around the rotation axis L at an angle corresponding to the first center angle ∠COD. The starting point is the first endpoint C of the feed port Lr, and the end point is the second endpoint D of the feed port Lr. The discharge port Lc is the line CC1D connecting the generatrix at the starting point CC1 of the rotation trajectory and the end point DC1 of the rotation trajectory, see Figure 1 .

[0079] like Figure 6-Figure 13 As shown, when the inner wall of the screening chamber 12 is the second rotating curved surface S2, the feed port Lr is an arc with a preset third central angle ∠COD, the rotation axis of the second rotating curved surface S2 is L, the generatrix is ​​CD1, and the rotation trajectory is from the first end point C to the second end point D of the arc where the feed port Lr is located. In some embodiments, the third central angle ∠COD is greater than or equal to 180° and less than or equal to 270°. In particular, taking the third central angle ∠COD equal to 180° as an example, the straight line CD is the diameter of the feed port Lr, the midpoint O is the center of the feed port Lr, the rotation axis L passes through the center O and is perpendicular to the first plane 11 where the feed port Lr is located, ∠CDC1 is equal to 45°, as shown Figure 7The fourth central angle is a preset angle of 90°. The generatrix CD1 is an arc. The center of the generatrix CD1 coincides with the center O of the inlet Lr. The radius of the generatrix CD1 is equal to the radius of the inlet Lr. The generatrix CD1 is coplanar with the rotation axis L. The first endpoint C of the generatrix CD1 coincides with the first endpoint C of the inlet Lr. The second endpoint D1 is located below the first endpoint C and on the rotation axis L based on the fourth central angle ∠COD1. The second rotation curved surface S2 is a rotation curved surface formed by the generatrix CD1 rotating about the rotation axis L along the rotation trajectory of the inlet Lr from its first endpoint C to its second endpoint D. The discharge port Lc is the generatrix at the starting and ending points of the trajectory and the line connecting them.

[0080] In some embodiments, it also includes a first spherical cap, the inner wall of the first spherical cap is a third rotational surface, the rotation axis of the third rotational surface is the same as the rotation axis of the first rotational surface, the center line of the third rotational surface is coplanar with the rotation axis, the first endpoint of the center line of the third rotational surface coincides with the second endpoint of the center line of the first rotational surface, the central angle of the center line of the third rotational surface is a preset fifth central angle, and the starting point and end point of the rotation trajectory of the center line of the third rotational surface are respectively the end point and starting point of the rotation trajectory of the center line of the first rotational surface.

[0081] Specifically, if Figure 1 and Figure 4 、 Figure 5 As shown, when the second central angle ∠CDC1 of the first rotational curved surface S1 is equal to 60°, the inner wall of the first spherical cap 13 is the third rotational curved surface S3, as shown in FIG. Figure 3 As shown, the rotation axis of the third rotation surface S3 is the rotation axis L of the first rotation surface S1, the first endpoint of the busbar of the third rotation surface S3 is the intersection point C1 of the busbar CC1 of the first rotation surface S1 and the rotation axis L, the second endpoint is D1, the center of the busbar C1D1 is point C, the radius is equal to the radius of the busbar CC1 of the first rotation surface S1, the busbar C1D1 is coplanar with the rotation axis L, the starting point of the rotation trajectory of the busbar C1D1 around the rotation axis L is the second endpoint D from the starting point feed port Lr, and the end point of the rotation trajectory is the first endpoint C of the feed port Lr. For example, when the first central angle ∠COD is equal to 180°, the rotation angle of the busbar C1D1 around the rotation axis L is 180°; when the first central angle ∠COD is equal to 270°, the rotation angle of the busbar C1D1 around the rotation axis L is 90°; when the first central angle ∠COD is equal to 240°, the rotation angle of the busbar C1D1 around the rotation axis L is 120°.

[0082] In some embodiments, the fifth central angle is greater than or equal to 15° and less than or equal to 30°.

[0083] Specifically, if Figure 3As shown, the value of the fifth central angle ∠C1CD corresponding to the busbar C1D1 is set according to specific needs, for example, 15°, 18°, 20°, 30°, etc.

[0084] In some embodiments, the fourth central angle is greater than or equal to 90° and less than or equal to 120°.

[0085] Specifically, if Figure 10 As shown, when the fourth center angle of the second rotation surface S2 is greater than 90°, the generatrix CD2 of the second rotation surface S2, the fourth center angle corresponding to the generatrix CD2 is ∠COD2, the generatrix CD2 is coplanar with the rotation axis L, point D1 is the intersection of the generatrix CD2 and the rotation axis L, that is, the rotation axis L is the straight line OD1, and the rotation trajectory of the generatrix CD2 is formed by rotating from its first endpoint C to the second endpoint D along the feed port Lr. The second rotation surface S2 includes: the curved surface formed by the arc CD1 rotating around the rotation axis L along the feed port Lr from its first endpoint C to the second endpoint D, and the curved surface formed by the arc D1D rotating around the rotation axis L along the feed port Lr from its second endpoint D to the first endpoint C. As shown Figure 8 and Figure 9 As shown, when the third central angle ∠COD is equal to 180°, the arc CD1 forms a quarter sphere around the rotation axis L, and the arc D1D forms the inner wall of the second spherical cap 14 by rotating 180° around the rotation axis L; when the third central angle ∠COD is equal to 270°, the arc D1D forms the inner wall of the second spherical cap 14 by rotating 90° around the rotation axis L; when the third central angle ∠COD is equal to 240°, the arc D1D forms the inner wall of the second spherical cap 14 by rotating 120° around the rotation axis L.

[0086] In another embodiment, Figure 10 , the fourth central angle ∠COD2 is greater than or equal to 105° and less than or equal to 120°. For example, the fourth central angle ∠COD2 is 105°, where the central angle ∠COD1 of arc CD1 is 90° and the central angle ∠D1OD2 of arc D1D2 is 15°; the fourth central angle ∠COD2 is 110°, where the central angle ∠COD1 of arc CD1 is 90° and the central angle ∠D1OD2 of arc D1D2 is 20°; and the fourth central angle ∠COD2 is 120°, where the central angle ∠COD1 of arc CD1 is 90° and the central angle ∠D1OD2 of arc D1D2 is 30°.

[0087] In some embodiments, the fourth central angle is greater than or equal to 30° and less than or equal to 60°. Figure 11-13As shown, when the inner wall of the screening chamber 12 is a second rotating curved surface S2, the feed port Lr is an arc with a preset third central angle ∠COD. The rotation axis of the second rotating curved surface S2 is L, the generatrix is ​​CD2, and the rotation trajectory is from the first endpoint C to the second endpoint D of the arc where the feed port Lr is located. In some embodiments, the third central angle ∠COD is greater than or equal to 180° and less than or equal to 270°. In particular, taking the third central angle ∠COD equal to 180° as an example, the straight line CD is the diameter of the feed port Lr, the midpoint O is the center of the feed port Lr, and the rotation axis L passes through the center O and is perpendicular to the first plane 11 where the feed port Lr is located. The fourth central angle ∠COD2 is a preset angle of 45°. Generatrix CD2 is an arc. The center of generatrix CD2 coincides with the center O of inlet Lr. The radius of generatrix CD2 is equal to the radius of inlet Lr. Generatrix CD2 is coplanar with the rotation axis L. The first endpoint C of generatrix CD2 coincides with the first endpoint C of inlet Lr. The second endpoint D2 is located below the first endpoint C based on the fourth central angle ∠COD1. The second rotation curved surface S2 is formed by generatrix CD2 rotating about the rotation axis L along the rotation trajectory of inlet Lr from its first endpoint C to its second endpoint D. The discharge port Lc is the generatrix at the starting and ending points of the trajectory and the line connecting them.

[0088] In some embodiments, the connection portion is provided with at least one limiting hole 15, for example, three. In other embodiments, the number of limiting holes 15 may be two, four, or the like. The limiting hole 15 connects the bottom of the connection portion with the first surface 11. The inner wall of the limiting hole 15 is threaded for mating with a fastener 6 having an external thread to achieve a fixed connection between the fine separator and the sieve plate.

[0089] On the other hand, a tobacco stem screen is provided, including: a screen plate 3, a plurality of circular screening holes 2 are provided on the screen plate 3, the screening holes 2 are connected to the upper and lower surfaces of the screen plate 3, and a plurality of refiners 1; a plurality of refiners are arranged on the lower surface of the screen plate 3, and the plurality of refiners correspond one-to-one to the plurality of screening holes 2, and the plurality of refiners adopt a combination of one or more of the first refiner, the second refiner and the third refiner, the first refiner, the second refiner and the third refiner all include a connecting portion and a screening cavity, the connecting portion has a first surface 11, the first surface 11 is parallel to the screen plate 3 and is fixedly connected to the lower surface of the screen plate 3, the screening cavity 12 is provided at one end of the connecting portion, the screening cavity 12 has an inlet and an outlet, and the plane where the inlet is located is coplanar with the first surface 11.

[0090] like Figure 1-Figure 3As shown, the inner wall of the screening chamber 12 of the first separator 1 adopts the first rotating surface S1, the feed port Lr is an arc with a preset first central angle ∠COD, and the feed port Lr is the rotation trajectory of the first endpoint C of the busbar CC1 of the first rotating surface S1 around the rotation axis L of the first rotating surface S1, the rotation axis L of the first rotating surface S1 passes through the center O of the feed port Lr and is perpendicular to the plane where the feed port Lr is located, the busbar of the first rotating surface S1 is the arc CC1 and is coplanar with the rotation axis L, the center and the first endpoint C of the busbar CC1 of the first rotating surface S1 are respectively the two endpoints of the diameter of the feed port Lr, the central angle of the busbar CC1 of the first rotating surface S1 is the second central angle, and the second endpoint of the busbar CC1 of the first rotating surface S1 is located below the starting point of the busbar. In particular, the second central angle ∠CDC1 is equal to 60°, then point C1 is the intersection of the busbar CC1 and the rotation axis L. The discharge port Lc is a line connecting the generatrix of the first rotating surface S1 at the starting point and the end point of the rotating trajectory, the diameter of the feed port Lr is equal to the diameter of the screening hole 2, and the rotation axis L of the first rotating surface S1 passes through the center of the screening hole 2. The feed port Lr of the first separator 1 and the screening hole 2 form an inlet window for the tobacco stems, and the lower surface of the sieve plate 3 and the discharge port of the first separator form a discharge window for the tobacco stems. In some embodiments, the first central angle of the first separator 1 is greater than or equal to 180° and less than or equal to 270°. The first separator whose inner wall of the screening chamber 12 is the first rotating surface S1 is called a type a1 separator.

[0091] The mechanical analysis of the a1 type precision separator is as follows. Figure 3 As shown, line segment CD represents a circle with center O and diameter φL; CC1 represents an arc with center D and radius L, and C1D represents an arc with center C and radius L. They are all arcs on the sphere, and they are all curved surfaces (spheres) obtained by rotating around C1O. It can be proved by geometry that points C, C1, and D can form an equilateral triangle with side length L; M1N1 and M4N4 represent tobacco stems, whose lengths are greater than L, and M2N2 and M3N3 represent tobacco stems, whose lengths are less than L. The vibrating screen exerts kinetic energy on the tobacco stems. If they fall into the spherical surface under the action of their respective gravity G, they will be subjected to the reaction force F of the spherical surface respectively. The reaction force F is actually provided by the vibrating screen mechanism, and its direction points to their respective centers (centers of the sphere). Objectively, the synthetic force of the reaction force F provided by the vibrating screen is much greater than the gravity G, which can be analyzed through theoretical mechanics. Figure 3The tobacco stems in the four states will produce different motion trajectories; among them, according to the decomposition and synthesis of the force, for example, long tobacco stems M1N1 and M4N4, whose size is greater than L, may bounce off the spherical surfaces CC1 and C1D, and will most likely bounce out of the circular hole with a diameter of CD without being separated; the synthetic force of short tobacco stems M3N3, whose size is less than L, will point to the escape window DD1, and will most likely jump into the window DD1 and be separated, while M2N2 tobacco stems have a certain probability of jumping into the window DD1 and being separated, or flipping with point N2 as the fulcrum and jumping into the window DD1. Figure 3 It is not difficult to understand that if the tobacco stem M4N4 is smaller than the length L, and there is only a reaction force F and gravity G acting on it, then the tobacco stem M4N4 will most likely jump directly into the window DD1 and be separated, but there is also a probability that the tobacco stem M4N4 will be ejected above point D and to the right of the OC1 line; it is also not difficult to understand that as long as the tobacco stem has only one contact point on the C1D1 segment surface (spherical surface), there is a certain probability that it will eject from the circular hole with a diameter of CD, and the direction is the same as the direction of the tobacco stem flowing from point D to point C. Side view (left side of the OC1 line); it can be seen that the C1D1 segment surface (spherical surface) also has high research value in improving separation accuracy. The C1D1 segment surface (spherical surface) is generally called a spherical cap in spatial geometry. If there is no spherical cap, it can be used for high-efficiency coarse separation of tobacco stems. That is to say, when there is a spherical cap, the amount of short stems in the separated long stems may increase. Therefore, the spherical cap design can prevent some tobacco stems from falling into the short stems from different directions in three-dimensional space, which is especially important at the tobacco stem feeding end.

[0092] Specific as Figure 4 、 Figure 5 As shown, in some embodiments, the first fine separator 1 also includes a first spherical cap 13, the inner wall of the first spherical cap 13 is a third rotation surface S3, the rotation axis of the third rotation surface S3 is the same as the rotation axis L of the first rotation surface S1, the center line of the third rotation surface S3 is coplanar with the rotation axis L, the first endpoint of the center line of the third rotation surface S3 coincides with the second endpoint C1 of the center line of the first rotation surface S3, the center angle of the center line C1D1 of the third rotation surface S3 is a preset fifth center angle, and the rotation trajectory starting point and the rotation trajectory end point of the third rotation surface center line S3 are respectively the rotation trajectory end point and the rotation trajectory starting point of the first rotation surface S3 center line. In some embodiments, the fifth center angle of the class a fine separator 1 is greater than or equal to 15° and less than or equal to 30°. As Figure 3 As shown, the value of the fifth central angle ∠C1CD corresponding to the busbar C1D1 is set according to specific needs, for example, 15°, 18°, 20°, 30°, etc. The first fine separator whose screening chamber 12 includes the first rotating curved surface and the third rotating curved surface is called a2 type fine separator.

[0093] Obviously, a single screening hole 2 cannot automatically sort, separate and classify a large number of flowing tobacco stems on the assembly line, and N holes are needed. When considering the separation efficiency and more sophisticated process requirements, spatial surfaces (spherical surfaces) with different geometric parameters should also be studied to meet different separation processes, such as coarse separation and fine separation. Even one-level vibration screening may not be enough, and two or three levels may be required. This is only for demanding process requirements. If the separation and classification process requirements are lowered, as long as the fine separators of different spatial surfaces (spherical surfaces) are reasonably and accurately planned and laid out, in some embodiments, only one-level vibration screening may be sufficient.

[0094] like Figure 6-Figure 13 As shown, the inner wall of the screening chamber 12 of the second fine separator adopts a second rotating surface S2, the feed port Lr is an arc with a preset third central angle ∠COD, and the feed port Lr is the rotation trajectory of the first end point C of the generatrix CD1 of the second rotating surface S2 around the rotation axis of the second rotating surface S2, the rotation axis L of the second rotating surface S2 passes through the center of the feed port Lr and is perpendicular to the plane where the feed port Lr is located, the generatrix of the second rotating surface S2 is an arc and is coplanar with the rotation axis L, and the second rotating surface S2 is a circular arc. The center of the generatrix CD1 of surface S2 coincides with the center of the feed port Lr. The central angle of the generatrix CD1 of the second rotational curved surface S2 is a preset fourth central angle. The second endpoint D1 of the generatrix CD1 of the second rotational curved surface S2 is located below the first endpoint C. The discharge port Lc is a line connecting the generatrixes of the second rotational curved surface S2 at the starting point and the end point of the rotation trajectory. The diameter of the feed port Lr is equal to the diameter of the sieve hole 2, and the rotation axis of the second rotational curved surface S2 passes through the center of the sieve hole 2. The feed port Lr of the second fine separator 1 and the sieve hole 2 form the feed window for the tobacco stems, and the lower surface of the sieve plate 3 and the discharge port of the second fine separator form the discharge window for the tobacco stems.

[0095] In some embodiments, the third center angle ∠COD is greater than or equal to 180° and less than or equal to 270°. In particular, taking the third center angle ∠COD equal to 180° as an example, Figure 10 As shown, the straight line CD is the diameter of the feed port Lr, the midpoint O is the center of the feed port Lr, and the rotation axis L passes through the center O and is perpendicular to the first plane 11 where the feed port Lr is located. The fourth central angle is a preset angle of 90°, the generatrix CD1 is an arc, the center of the generatrix CD1 coincides with the center O of the feed port Lr, and the second end point D1 is located below the first end point C and on the rotation axis L according to the fourth central angle ∠COD1. This forms the following Figure 6 The second divider shown, in which the fourth central angle of the second rotation surface is 90°, is called a b1 divider.

[0096] In some embodiments, the fourth center angle of the second fine separator 1 is greater than or equal to 90° and less than or equal to 120°. In some other embodiments, the fourth center angle of the second fine separator 1 is greater than or equal to 105° and less than or equal to 120°. Specifically, Figures 8-10 As shown, when the fourth center angle of the second rotational surface S2 is greater than 90°, the generatrix CD2 of the second rotational surface S2, the fourth center angle corresponding to the generatrix CD2 is ∠COD2, the generatrix CD2 is coplanar with the rotation axis L, point D1 is the intersection of the generatrix CD2 and the rotation axis L, that is, the rotation axis L is the straight line OD1, the rotation trajectory of the generatrix CD2 is rotating from its first endpoint C to the second endpoint D along the feed port Lr, then the arc CD1 rotates around the rotation axis L along the feed port Lr from its first endpoint C to the second endpoint D to form a curved surface, and the arc D1D rotates around the rotation axis L along the feed port Lr from its second endpoint D to the first endpoint C to form a curved surface. Figure 8 and Figure 9 As shown, when the third central angle ∠COD is equal to 180°, the arc CD1 forms a quarter sphere around the rotation axis L, and the arc D1D forms the inner wall of the second spherical cap 14 by rotating 180° around the rotation axis L; when the third central angle ∠COD is equal to 270°, the arc D1D forms the inner wall of the second spherical cap 14 by rotating 90° around the rotation axis L; when the third central angle ∠COD is equal to 240°, the arc D1D forms the inner wall of the second spherical cap 14 by rotating 120° around the rotation axis L, as shown in FIG. Figure 9 and Figure 10 The divider shown in the figure is a second divider whose fourth central angle of the second rotation surface is greater than 90° and is a type b2 divider.

[0097] The mechanical analysis of the b1 class fine separator for high-accuracy separation of short stems smaller than L and containing fewer long stems is as follows. Figure 7 As mentioned above. Line segment CD represents a circle with center O and diameter φL; arc CD1 represents an arc surface with center O and radius φL / 2, which is an arc surface on the sphere obtained by rotating OD1 as the center line. It can be proved by geometry that points C, D1, and D can form a right angle with a side length of isosceles right triangle; M1N1, M2N2, and M3N3 represent tobacco stems, where the length of M2N2 tobacco stem is less than L. If they fall into the sphere under the action of their respective gravity G, they will be subjected to the reaction force F of the sphere, and similarly, their directions point to their respective centers (centers of the sphere). According to the principles of plane geometry, the length of D1D is According to the above analysis and research method, the maximum length of tobacco stem M3N3 can be close to Obviously, the stem length controlled by the arc of the sphere with point D as the center and radius L is smaller than that of the sphere, but the separation efficiency is high, and the probability of containing stems smaller than L in long stems larger than L increases. Therefore, it can be used for coarse separation.

[0098] like Figure 10 As shown in the figure. If you want to further accurately separate the tobacco stems, add a designed arc segment D1D2, whose central angle is 30°. After rotating in space, it is called a spherical cap 14. The spherical cap 14 represents a solid angle of 60° in spatial geometry. According to the principles of plane geometry, points D2, O, and D can form an equilateral triangle, and the length of D2D is L / 2. According to the above analysis and research method, the maximum length of the separated tobacco stems can be close to the L value. Therefore, the amount of tobacco stems greater than the L value contained in the short stems less than the L value separated by this method will be very small, but the separated long stems are likely to contain short stems. Therefore, it should be used according to the flow rate of tobacco stems and process requirements.

[0099] In some embodiments, the fourth central angle of the second fine divider 1 is greater than or equal to 30° and less than or equal to 60°. Figure 11-13 As shown, when the inner wall of the screening chamber 12 is a second rotating curved surface S2, the feed port Lr is an arc with a preset third central angle ∠COD. The rotation axis of the second rotating curved surface S2 is L, the generatrix is ​​CD2, and the rotation trajectory is from the first endpoint C to the second endpoint D of the arc where the feed port Lr is located. In some embodiments, the third central angle ∠COD is greater than or equal to 180° and less than or equal to 270°. In particular, taking the third central angle ∠COD equal to 180° as an example, the straight line CD is the diameter of the feed port Lr, the midpoint O is the center of the feed port Lr, and the rotation axis L passes through the center O and is perpendicular to the first plane 11 where the feed port Lr is located. The fourth central angle ∠COD2 takes a preset angle of 45°, the busbar CD2 is an arc, the center of the busbar CD2 coincides with the center O of the feed inlet Lr, the radius of the busbar CD2 is equal to the radius of the feed inlet Lr, and the busbar CD2 is coplanar with the rotation axis L. The first endpoint C of the busbar CD2 coincides with the first endpoint C of the feed inlet Lr, and the second endpoint D2 is located below the first endpoint C according to the fourth central angle ∠COD1. The second rotation surface S2 is a rotation surface formed by the busbar CD2 rotating around the rotation axis L along the rotation trajectory of the feed inlet Lr from its first endpoint C to its second endpoint D. The discharge port Lc is the busbar of the starting point and the end point of the trajectory and the line connecting them. Figure 11-12 The divider shown in the figure, wherein the second divider whose fourth central angle of the second rotation surface is greater than or equal to 30° and less than or equal to 60° is called a b3 type divider.

[0100] The mechanical analysis of some b3 class separators is as follows: Figure 13As shown, for situations where tobacco stem flow is low, directional flow is highly consistent, stem flow is fast, and separation accuracy requirements are low, a spatial circular curve surface design with even higher separation efficiency is proposed. This design, again using OD1 as the rotation centerline, utilizes arc CD2 to generate a spatial curved surface. The central angle a of this curved surface within the cross section ranges from 30° to 60°, with a value of 45° being optimal. Its theoretical control length is designed to be L according to process requirements. Due to the small number of control arc surfaces, efficiency is high. This is a highly efficient separation and classification method for special conditions such as low flow rates.

[0101] Figure 14-15 As shown, the inner wall of the screening chamber 12 of the third fine separator 1 adopts the fourth rotation surface S4, the feed port Lr is an arc with a preset sixth central angle ∠CDE, and the feed port Lr is the rotation trajectory of the first end point C of the generatrix CD1 of the fourth rotation surface S4 around the rotation axis L of the fourth rotation surface S4, the rotation axis L of the fourth rotation surface S4 passes through the center point D of the feed port Lr and is perpendicular to the plane where the feed port Lr is located, the generatrix CD1 of the fourth rotation surface S4 is an arc and Coplanar with the rotation axis L, the center of the generatrix CD1 of the fourth rotation surface S4 coincides with point D of the feed port Lr, the central angle of the generatrix CD1 of the fourth rotation surface S4 is the preset seventh central angle ∠CDD1, the second endpoint D1 of the generatrix of the fourth rotation surface S4 is located below the first endpoint C, the discharge port Lc is the line connecting the generatrix of the fourth rotation surface S4 at the starting point and the end point of the rotation trajectory, and the radius RL of the feed port Lr is equal to the diameter of the screening hole 2 The screening hole 2 is inscribed in the middle point F of the feed inlet Lr ( Figure 17 ), that is, the diameter of the sieve hole 2 The circle with radius RL of the feed inlet Lr is tangent to point F (Note: Figure 16 Point C and Figure 17 The screen holes 2 and the diameter CE of the feed inlet Lr are tangent to the center D of the circle of the feed inlet Lr. The feed inlet Lr of the third fine separator 1 and the screen holes 2 form the tobacco stem inlet window, and the lower surface of the screen plate 3 and the discharge port of the Class C fine separator form the tobacco stem discharge window.

[0102] In some embodiments, the sixth central angle of the third fine divider 1 is greater than or equal to 180° and less than or equal to 270°. Figure 14As shown, taking the sixth central angle ∠CDE as 180° as an example, line CD is the radius of the arc of inlet Lr, with a magnitude equal to L. The rotation axis L passes through the center D of arc CD1 and is perpendicular to the first plane 11 where inlet Lr is located. The seventh central angle is a preset angle of 90°. Generatrix CD1 is an arc, the center of which coincides with the center D of inlet Lr. The radius of generatrix CD1 is equal to the radius of inlet Lr, and generatrix CD1 is coplanar with the rotation axis L. The first endpoint C of generatrix CD1 coincides with the first endpoint C of inlet Lr. The second endpoint D1 is located below the first endpoint C and on the rotation axis L based on the seventh central angle ∠COD1. The fourth rotation curved surface S4 is formed by the rotation of generatrix CD1 around the rotation axis L along the rotation trajectory of inlet Lr from its first endpoint C to its second endpoint E. The discharge port Lc is the generatrix of the trajectory starting point and the trajectory end point and the connecting line thereof. The third fine separator with the seventh central angle of the fourth rotation surface equal to 90° is called a c1 type fine separator.

[0103] In some embodiments, the seventh central angle of the third fine separator 1 is greater than or equal to 90° and less than or equal to 120°. In some other embodiments, the seventh central angle of the third fine separator 1 is greater than or equal to 105° and less than or equal to 120°. Specifically, Figure 16-19 As shown, when the seventh central angle of the fourth rotation surface S4 is greater than 90°, the generatrix CD2 of the fourth rotation surface S4 and the seventh central angle corresponding to the generatrix CD2 are ∠C OD2, the busbar CD2 is coplanar with the rotation axis L, and point D1 is the intersection of the busbar CD2 and the rotation axis L. That is, the rotation axis L is the straight line OD1, and the rotation trajectory of the busbar CD2 is the curved surface formed by rotating along the feed port Lr from its first endpoint C to its second endpoint E, including the curved surface formed by the arc CD1 rotating around the rotation axis L along the feed port Lr from its first endpoint C to its second endpoint E, and the curved surface formed by the arc D1D2 rotating around the rotation axis L along the feed port Lr from its second endpoint E to its first endpoint C. Figure 16 and Figure 19 As shown, when the sixth central angle ∠CDE is equal to 180°, the arc CD1 forms a quarter sphere around the rotation axis L, and the arc D1D2 forms the inner wall of the second spherical cap 14 by rotating 180° around the rotation axis L; when the sixth central angle ∠CDE is equal to 270°, the arc D1D2 forms the inner wall of the third spherical cap 16 by rotating 90° around the rotation axis L; when the sixth central angle ∠CDE is equal to 240°, the arc D1D2 forms the inner wall of the third spherical cap 16 by rotating 120° around the rotation axis L, as shown in FIG. Figure 16 and Figure 19 The divider shown is a third divider c2 type divider in which the seventh central angle of the fourth rotation surface is greater than 90°.

[0104] Class C fine separators can achieve efficient separation and obtain more than or The technical effect is to separate the long stems and contain less short stems. It can also be used for the initial separation of long stems by multi-stage vibration screening, and the next step is to finely separate the tobacco stems within the length L value according to the above method. Figure 15 As shown, in the c1 category, the line segment CD represents a circular screening hole with O as the center and a diameter of φL; the CD1 arc represents an arc with D as the center and L as the radius. It is an arc surface on the sphere obtained by rotating with DD1 as the center line. It can be proved by geometry that points C, D1, and D can form an isosceles right triangle with a right-angled side length of L; M1N1, M2N2, M3N3, and M4N4 represent tobacco stems respectively. The length of these tobacco stems is greater than the L value. Obviously, if they fall into the spherical surface CD1 arc under the action of their respective gravity G, they will be subjected to the reaction force F of the sphere respectively. Similarly, there is a high probability that they will pop out of the circular hole with CD as the diameter, and it is not easy to directly jump into the window DD1 and enter the short stem category. However, it is also possible that tobacco stems with a length greater than L value enter the window DD1 from other spatial states and enter the short stem category. Theoretically, if Figure 15 In the C1 class fine separator, the maximum value of the tobacco stem falling on the sphere with two end points in contact is: (Theoretically, the length of line segment CD1). This is a method to efficiently obtain long stems greater than the L value and minimize the content of short stems less than the L value. However, the separated short stems less than the L value will contain more long stems greater than the L value. Therefore, further separation is required, or in order to further reduce their content,

[0105] like Figure 16 As shown in Figure 2, for type c2, the arc segment D1D2 can be added to the design, and its central angle is still 30°, that is, the design adds a spherical cap. Figure 16 In the figure, one end point C of the tobacco stem touches the sphere, and the other end point D2 touches the spherical crown. Points C, D, and D2 form an isosceles triangle, and ∠CDD2 is equal to 120°. Then the maximum CD2 length of the tobacco stem is:

[0106] In any of the above-mentioned spatial circular curve surface designs with a spherical crown, in addition to improving the separation accuracy, there are other higher technological values. For example, in the tobacco stem feeding area, within a range of about 300mm, the tobacco stems are seriously accumulated. When the vibration screen fails to perfect its directional flow, a large number of long stems greater than the L value can be prevented from being separated into short stems less than the L value.

[0107] On the other hand, the above separation and classification methods are all based on the principle of hemispherical theory, which takes into account the balance between spherical length control and tobacco stem outlet. If the accuracy of tobacco stem classification is to be improved, the solid angle of the sphere should be considered as a control parameter. According to calculus and spatial analytic geometry, the solid angle is the ratio of the projected area to the square of the sphere radius: dΩ = dA / r 2 =sinθdθdψ, through integration we can get: Ω=∫∫ s dΩ=∫∫s sinθdθdψ, which is a universal expression in the spherical coordinate system. Simply put, for this technical research plan, the solid angle Ω of the sphere is the square of the sphere area S divided by the radius r, because the area of ​​the sphere S = 4πr 2 , it can be seen that the solid angle of a sphere is Ω=4π, and the solid angle of a hemisphere is Ω=2π. Therefore, in the various methods mentioned above, the solid angle of a spherical surface (excluding the spherical crown) using controlled length is Ω=π. Therefore, to improve the accuracy of separating tobacco stems, theoretically, the solid angle Ω must be increased. For example, on the basis of the above, Ω=π~3π / 2 is made. In this way, the accuracy of separating tobacco stems is improved, but the separation efficiency may be reduced, and the separator may be jammed, etc. Due to the complexity of the spatial position of tobacco stems in the vibrating screen, the physical properties of tobacco stems, vibrating screen performance and process requirements of tobacco stem classification should be specifically analyzed to decide whether to increase the solid angle Ω or select a suitable solid angle Ω. Figure 20 In the b2 type fine divider, the solid angle Ω is increased by using the curved surface containing the spherical cap; Figure 21 In the figure, after increasing the solid angle Ω, it is a schematic diagram of the alignment of the spherical circle and the screening hole 2 on the screen plate 3. In addition, thin parts can also be manufactured using stamping dies or machining techniques, such as Figure 20 .

[0108] In some embodiments, the connecting portion is provided with at least one limiting hole, the limiting hole communicating with the bottom of the connecting portion and the first surface. Figures 1-19 As shown, for example, there are three limiting holes 15. In other embodiments, the number of limiting holes 15 can be two, four, etc. The limiting holes 15 connect the bottom of the connecting portion and the first surface 11. The inner wall of the limiting holes 15 is threaded for matching the fastener 6 with an external thread to achieve a fixed connection between the fine separator 1 and the sieve plate 3. These limiting holes are also called positioning threaded holes in mechanical engineering.

[0109] In some embodiments, such as Figure 22 As shown, the system further includes two guard plates 4 and multiple cosine guide plates 5. The two guard plates 4 are respectively arranged at both ends of the screen plate 3, and the multiple cosine guide plates 5 are evenly arranged between the two guard plates 4. The multiple screening holes 2 are distributed in rows, and each row of screening holes 2 is spaced apart from the cosine guide plates 5. Since the vibrating screen generally has simple harmonic vibration and a mathematical function, in order to make the tobacco stems flow more smoothly, the cosine guide plates 5 should be designed as a cosine function curve, with an amplitude of 2 to 5 times the amplitude of the vibrating screen used and a wavelength of 3 to 10L.

[0110] In some embodiments, the distance between the centers of any two adjacent sieve holes 2 among the plurality of sieve holes 2 is greater than twice the diameter of the sieve hole 2 and less than 2.5 times the diameter of the sieve hole 2 .

[0111] For the first-stage vibrating screen, any one or more combinations of a1, a2, b1, b2, b3, c1, and c2 in the spatial size classifier 1 can be installed on the same sieve plate 3; for the multi-stage vibrating screen, the aperture value φL of the screening holes on the sieve plate 3 may not be equal, and any one or more combinations of a1, a2, b1, b2, b3, c1, and c2 in the spatial size classifier 1 corresponding to the size can be installed.

[0112] It is a highly targeted process method. If any combination of class a1, class a2, class b1, class b2, class b3, class c1, and class c2 is on the same sieve plate 3 of the first-level vibration screen, and the separation and classification effect can achieve the process effect, then the first-level vibration screen may be able to achieve the process effect.

[0113] like Figure 23 Schematic diagram of the method of installing class B2, class A1 and class B1 in the spatial size separator 1 on the same sieve plate 3, among which the one with a spherical crown is installed at the front input end of the material of the vibrating screen, the middle end can be installed with class A with high separation efficiency, and the end can be installed with class B with high separation accuracy.

[0114] Obviously, the use of multi-stage vibrating screens to implement the classification of tobacco stems of multiple sizes L can use any design of the aforementioned Class A fine separator, or Class B fine separator, or Class C fine separator of different sizes L, installed on screens of different vibration levels. With multi-stage vibrating screens, classification of tobacco stems of different sizes can also be achieved. For example, if the first-stage vibrating screen has a screening aperture of 3L, the second-stage vibrating screen has a screening aperture of 2L, and the third-stage vibrating screen has a screening aperture of L, classification according to different size requirements can be achieved. These are all based on tobacco processing requirements.

[0115] While various embodiments of the present disclosure have been described above, the foregoing description is intended to be illustrative, non-exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or technological improvements in the marketplace, or to enable others skilled in the art to understand this document.

Claims

1. A tobacco stem separator for classification by geometric size, characterized in that: The fine separator includes a connecting portion and a screening cavity, the connecting portion has a first surface, the first surface is used to connect the screen plate, the screening cavity is arranged at one end of the connecting portion, the screening cavity is provided with an inlet and an outlet, the plane where the inlet is located is coplanar with the first surface, and the inner wall of the screening cavity is any one of a first rotation curved surface and a second rotation curved surface, wherein, The feed port is an arc with a preset first central angle, and the feed port is a rotation trajectory of the first endpoint of the generatrix of the first rotational curved surface around the rotation axis of the first rotational curved surface, the rotation axis of the first rotational curved surface passes through the center of the feed port and is perpendicular to the plane where the feed port is located, the generatrix of the first rotational curved surface is an arc and is coplanar with the rotation axis, the center and the first endpoint of the generatrix of the first rotational curved surface are respectively the two endpoints of the feed port diameter, the central angle of the generatrix of the first rotational curved surface is a preset second central angle, the second endpoint of the generatrix of the first rotational curved surface is located below the starting point of the generatrix, and the discharge port is a line connecting the generatrix of the first rotational curved surface at the starting point and the end point of the rotation trajectory; Or, the feed port is an arc with a preset third central angle, and the feed port is the rotation trajectory of the first end point of the busbar of the second rotation surface around the rotation axis of the second rotation surface, the rotation axis of the second rotation surface passes through the center of the feed port and is perpendicular to the plane where the feed port is located, the busbar of the second rotation surface is an arc and is coplanar with the rotation axis, the center of the busbar of the second rotation surface coincides with the center of the feed port, the central angle of the busbar of the second rotation surface is a preset fourth central angle, the second end point of the busbar of the second rotation surface is located below the first end point, and the discharge port is the line connecting the busbars of the second rotation surface at the starting point and the end point of the rotation trajectory.

2. The fine separator according to claim 1, characterized in that The first central angle is greater than or equal to 180° and less than or equal to 270°.

3. The fine separator according to claim 2, characterized in that The second central angle is equal to 60°.

4. The fine separator according to claim 3, characterized in that It also includes a first spherical cap, the inner wall of the first spherical cap is a third rotational surface, the rotation axis of the third rotational surface is the same as the rotation axis of the first rotational surface, the generatrix of the third rotational surface is coplanar with the rotation axis, the first endpoint of the generatrix of the third rotational surface coincides with the second endpoint of the generatrix of the first rotational surface, the central angle of the generatrix of the third rotational surface is a preset fifth central angle, and the starting point and end point of the rotation trajectory of the generatrix of the third rotational surface are respectively the end point and starting point of the rotation trajectory of the generatrix of the first rotational surface.

5. The fine separator according to claim 4, characterized in that: The fifth central angle is greater than or equal to 15° and less than or equal to 30°.

6. The fine separator according to claim 1, characterized in that The third central angle is greater than or equal to 180° and less than or equal to 270°.

7. The fine separator according to claim 6, characterized in that: The fourth central angle is equal to 90° and less than or equal to 120°; or the fourth central angle is greater than 90° and less than or equal to 120°; or the fourth central angle is greater than or equal to 30° and less than or equal to 60°.

8. The fine separator according to claim 1, characterized in that: The connecting portion is provided with at least one limiting hole, and the limiting hole communicates with the bottom of the connecting portion and the first surface.

9. A tobacco stem screen, characterized in that: include: A sieve plate, wherein a plurality of circular sieve holes are provided on the sieve plate, wherein the sieve holes are connected to the upper and lower surfaces of the sieve plate, and a plurality of fine separators; A plurality of the fine separators are arranged on the lower surface of the sieve plate, and the plurality of the fine separators correspond one-to-one to the plurality of the sieve holes. The plurality of fine separators adopt a combination of one or more of the first fine separator, the second fine separator and the third fine separator. The first fine separator, the second fine separator and the third fine separator all include a connecting portion and a sieve cavity. The connecting portion has a first surface, the first surface is parallel to the sieve plate and is fixedly connected to the lower surface of the sieve plate. The sieve cavity is arranged at one end of the connecting portion. The sieve cavity is provided with an inlet and an outlet. The plane where the inlet is located is coplanar with the first surface, wherein, The first fine separator is the fine separator according to any one of claims 1 to 5, the arc diameter of the feed inlet is equal to the diameter of the sieve hole, and the rotation axis of the first rotating curved surface passes through the center of the sieve hole; The second fine separator adopts the fine separator according to claim 1 or any one of claims 6-7, the arc diameter of the feed port is equal to the diameter of the sieve hole, and the rotation axis of the second rotating curved surface passes through the center of the sieve hole; The inner wall of the screening chamber of the third refiner adopts a fourth rotational curved surface, the feed port is an arc with a preset sixth central angle, and the feed port is a rotation trajectory of the first end point of the generatrix of the fourth rotational curved surface around the rotation axis of the fourth rotational curved surface, the rotation axis of the fourth rotational curved surface passes through the center of the feed port and is perpendicular to the plane where the feed port is located, the generatrix of the fourth rotational curved surface is an arc and is coplanar with the rotation axis, the center of the generatrix of the fourth rotational curved surface coincides with the center of the feed port, the central angle of the generatrix of the fourth rotational curved surface is a preset seventh central angle, the second end point of the generatrix of the fourth rotational curved surface is located below the first end point, the discharge port is a line connecting the generatrix of the fourth rotational curved surface at the starting point and the end point of the rotation trajectory, the radius of the feed port is equal to the diameter of the screening hole, the screening hole and the feed port are tangent at the midpoint of the feed port, and the screening hole and the diameter of the feed port are tangent at the center of the feed port.

10. The screen according to claim 9, characterized in that The sixth central angle of the third fine divider is greater than or equal to 180° and less than or equal to 270°.

11. The screen according to claim 10, characterized in that The seventh central angle of the third divider is greater than or equal to 90° and less than or equal to 120°, or the seventh central angle of the third divider is greater than or equal to 105° and less than or equal to 120°.

12. The screen according to claim 11, characterized in that The connecting portion is provided with at least one limiting hole, and the limiting hole communicates with the bottom of the connecting portion and the first surface.

13. The screen according to claim 12, characterized in that It also includes two guard plates and multiple cosine guide plates, the two guard plates are respectively arranged at the two ends of the screen plate, the multiple cosine guide plates are evenly arranged between the two guard plates, the multiple screening holes are distributed in rows, and each row of screening holes is spaced apart from the cosine guide plates.

14. The screen according to claim 13, characterized in that The distance between the centers of any two adjacent sieve holes among the plurality of sieve holes is greater than 2 times the diameter of the sieve hole and less than 2.5 times the diameter of the sieve hole.

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