Buckling beam gravity screening method and screening device

Abstract

The invention belongs to the technical field of gravity screening, and relates to a buckling beam gravity screening method and screening device.The method comprises the steps that 1, one end of a straight beam is fixed in the axial direction, axial force is applied to the other end of the straight beam, and the straight beam is bent to become a buckling beam; 2, by adjusting the axial distance reduction amount of the buckling beam and / or the geometric dimension of the buckling beam, the magnitude of transverse force capable of enabling the buckling beam to generate transverse displacement and jump is set; 3, adjusting the buckling beam to an upper stable balance position; 4, enabling the to-be-screened object to pass through the buckling beam by self weight; 5, enabling the buckling beam to jump to a lower stable balance position by the to-be-screened object of which the dead weight is greater than the transverse force; 6, the objects to be screened at the stable balance positions under the buckling beams are recycled, screening is completed, the minimum weight of the objects capable of being screened out of each column of buckling beams is obtained according to the geometric size and the reduction amount of the beams, and automatic rolling, screening and classification of the objects to be screened are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of gravity screening, and relates to a buckled beam gravity screening method and a screening device. Background Art

[0002] Gravity screening is a technology that uses the weight differences between materials to separate them under the influence of gravity. The basic principle is that in a specific medium (such as air or water), materials of different weights are grouped due to the different gravitational forces they experience. Gravity screening is widely used in mineral resources, agriculture, food processing, and other fields.

[0003] In the agricultural sector, the price of agricultural products is determined not only by their appearance and quality but also by their weight. For example, for potatoes, oblong radishes, taro, and cabbage, these prices are high. Given these price points, weighing and sorting individual products is time-consuming and labor-intensive, ultimately increasing their price. Therefore, many agricultural products are screened by weight using manual visual recognition. However, existing agricultural product screening methods have the following drawbacks: 1. The weight of the items being screened is directly dependent on the screener's personal perception, resulting in a wide range of weight variations. 2. Not only is screening inefficient, but it also introduces significant labor costs.

[0004] Therefore, from the perspective of facilitating the classified sales of agricultural products and increasing the personal income of agricultural practitioners, a simple, fast and convenient gravity screening method or screening device is needed to solve the above technical problems. Summary of the Invention

[0005] The technical solution adopted by the present invention to solve the technical problem is: a buckled beam gravity screening method, comprising the following steps:

[0006] Step 1: Fix one end of the straight beam axially and apply an axial force inward at the other end of the straight beam so that the axial force is greater than the critical force, causing the straight beam to buckle and become a buckled beam. A buckled beam has at least an upper stable equilibrium position and a lower stable equilibrium position. t When in action, the buckled beam rapidly produces a jump phenomenon to screen the objects to be screened;

[0007] Step 2: By adjusting the axial distance reduction of the buckled beam after the straight beam is subjected to the axial force and / or the geometric dimensions of the buckled beam, the geometric dimensions include the length, width and thickness of the buckled beam, and setting the magnitude of the lateral force that can cause the buckled beam to produce a jump in lateral displacement. The lateral force refers to the force perpendicular to the length direction of the straight beam; by adjusting the axial distance reduction of the buckled beam Δl c , the geometric dimensions of the buckled beam, such as the length, width and thickness of the cross section of the buckled beam, etc., can be adjusted to cause the lateral force of the buckled beam to jump from the upper stable equilibrium position to the lower stable equilibrium position; greater than

[0008] Step 3: Adjust the buckling beam to the upper stable equilibrium position; after adjusting the magnitude of the lateral force, adjust the buckling beam to the upper stable equilibrium position so that the objects to be screened can be screened at any time;

[0009] Step 4: Allow the object to be screened to pass through the stable equilibrium position on the buckling beam under its own weight;

[0010] Step 5: The objects to be screened whose weight is greater than the lateral force are subjected to gravity, causing the buckling beam to jump to the lower stable equilibrium position and be screened out; the objects to be screened whose weight is less than or equal to the lateral force are screened by the buckling beam; when the weight G of the objects to be screened is greater than the lateral force F t When the weight G of the object to be screened is applied, the buckled beam jumps from the upper stable equilibrium position to the lower stable equilibrium position, and the weight G is greater than the lateral force F. t of materials to be screened;

[0011] Step 6: Recover the objects to be screened at the stable equilibrium position under the buckled beam, and complete the screening of the objects to be screened whose deadweight is greater than the lateral force.

[0012] Preferably, in step 2, the magnitude of the lateral force is:

[0013]

[0014] In formula (2), F t represents the lateral force, A represents the cross-sectional area of the buckled beam, E represents the elastic modulus of the buckled beam material, I represents the section moment of inertia of the buckled beam, l represents the distance between the two ends of the buckled beam, and u represents the cross-sectional area of the buckled beam. y represents the lateral displacement of the buckled beam under the action of lateral force, l0 represents the free length of the straight beam, Δl c represents the reduction in the axial distance of the buckled beam, where Δl c =l0-l; According to the parameters in formula (2), buckling beams of different materials, models and sizes can be selected, and different axial distance reduction amounts can be loaded on the selected buckling beams as needed so that the lateral force of the buckling beam reaches the screening target weight.

[0015] More preferably, in step 2, the axial distance reduction of the buckled beam is adjusted by fine thread Δl c , the relationship between the reduction in the axial distance of the buckled beam and the fine thread is:

[0016]

[0017] In formula (3), λ represents the pitch of the fine thread, and θ represents the rotation angle of the fine thread. The axial distance reduction of the buckled beam is set according to the pitch and rotation angle of the thread so that the lateral force of the buckled beam reaches the screening target weight.

[0018] Preferably, in step 5, a buckling beam reset mechanism is provided at the lower stable equilibrium position so that when the object to be screened leaves the buckling beam, the buckling beam jumps and resets again to return to the upper stable equilibrium position; the buckling beam reset mechanism enables the buckling beam to repeatedly perform jump screening multiple times, thereby realizing a continuous screening or automatic screening function;

[0019] In step 6, a recovery device is set at the lower stable equilibrium position to recover the objects to be screened so that the objects to be screened are separated from the buckling beam; the recovery device is used to assist the reset mechanism to realize continuous screening or automatic screening functions, and at the same time can classify and collect the screened objects according to the set weight range of the objects to be screened, so as to facilitate subsequent screening processes.

[0020] Preferably, multiple buckling beams are provided, and the multiple buckling beams are provided with multiple lateral forces of different sizes, so that the objects to be screened pass through the stable equilibrium positions on different buckling beams in sequence with their own weight, thereby completing the screening of objects to be screened within different weight ranges, for example, the buckling beams are arranged in sequence from large to small with lateral forces; multiple buckling beams are arranged and combined according to different needs and different screening amounts, so as to achieve the screening purpose, for example, multiple screening channels can be arranged in parallel to carry out multiple screenings at the same time; or a single screening channel is used to arrange multiple buckling beams with different lateral force sizes in a stepped manner along the length direction of the screening channel, so that the objects to be screened are screened according to the adjacent lateral force size ranges; or multiple screening channels are combined with the stepped buckling beam method to quickly and effectively screen out objects to be screened of target weight.

[0021] The present invention also discloses a buckling beam gravity screening device, which adopts the above-mentioned screening method. The screening device comprises: a buckling beam, an axial force adjustment device, one end of the buckling beam is fixed in the axial direction, the other end of the buckling beam is fixedly connected to the axial telescopic end of the axial force adjustment device, and the fixing portion of the axial force adjustment device is fixed;

[0022] After the axial distance of the axial force adjustment device is adjusted, the buckled beam has an arched upper stable equilibrium position and a lower stable equilibrium position;

[0023] A screening channel is provided in the middle of the upper surface of the buckled beam. The screening channel can be selected to be perpendicular to the length direction of the buckled beam. The screening channel is located exactly at the top of the arch at the upper stable equilibrium position, so that the weight of the object to be screened is closer to the lateral force caused by the jump of the buckled beam, and the screening accuracy is higher.

[0024] Preferably, a reset device is provided in the middle of the lower surface of the buckling beam, and the reset device is used to reset the buckling beam to jump back to the upper stable equilibrium position when the buckling beam jumps to the lower stable equilibrium position. The reset device includes a telescopic mechanism such as a spring and a piston. The reset device can be installed on the frame of the buckling beam when the buckling beam jumps to the lower stable equilibrium position, so that the fixed part of the reset device is installed on the frame, and the telescopic part of the reset device faces the bottom of the buckling beam, or the fixed part of the reset device is installed at the bottom of the buckling beam, and the telescopic part of the reset device faces the reset contact on the frame; when the buckling beam carrying the object to be screened jumps from the upper stable equilibrium position to the lower stable equilibrium position, the distance between the bottom of the buckling beam and the frame is reduced, compressing the reset device, and storing kinetic energy for resetting the reset device. When the object to be screened leaves the buckling beam, the reset device releases the kinetic energy, and resets the buckling beam from the lower stable equilibrium position back to the upper stable equilibrium position.

[0025] Preferably, the axial force adjustment device is a threaded connection device, which is provided with an adjustment handle linked to the axial telescopic end of the threaded connection device, and a pointer is provided on the adjustment handle. A dial is provided on the fixed portion of the threaded connection device, and the pointer points to the scale on the dial; the pointer and the dial scale cooperate so that when manually adjusting the threaded connection device, the lateral force F that needs to be adjusted can be intuitively understood. t Magnitude and current lateral force F t Size, thereby setting the weight of the object to be screened.

[0026] Preferably, a recovery device is provided at the lower stable equilibrium position of the buckling beam; the recovery device is used to assist the reset mechanism in realizing continuous screening or automatic screening functions, and at the same time can classify and collect the screened objects according to the set weight range of the objects to be screened, so as to facilitate subsequent screening processes.

[0027] Preferably, there are multiple buckling beams, and the multiple buckling beams are arranged in sequence along the length direction of the screening channel. The lateral forces of the multiple buckling beams are set in sequence from large to small along the length direction of the screening channel; the multiple buckling beams are arranged and combined according to different needs to achieve different screening purposes.

[0028] The beneficial effects of the present invention are:

[0029] 1. The present invention is based on the theory of buckled beam vibration, according to the geometric dimensions of the beam and the reduction amount Δl c The minimum weight of the object that can be screened out by each column of buckled beams can be directly and accurately obtained; in addition, the Δl of this column can also be c Adjustment is performed to achieve stepless adjustment of the screening weight of this column of buckling beams.

[0030] 2. The present invention does not require an external power source and can be applied to a variety of outdoor environments. It has a simple structure and is a green power and easy-to-use gravity screening device.

[0031] 3. The present invention can realize automatic rolling down of objects to be screened under the action of gravity and realize automatic classification.

[0032] 4. The present invention installs multiple parallel buckling beams on an inclination angle adjustment frame. The inclination angle can be increased or decreased by adjusting the rise or fall of one end. The rolling speed of objects passing through each buckling beam screening device can be controlled at any time according to the physical properties of different objects.

[0033] 5. The multiple parallel buckling beams of the present invention can be arbitrarily selected or combined. Buckling beams that are not needed can be adjusted to the maximum weight and will not respond to passing objects, thereby not performing screening actions. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The present invention is a buckled beam gravity screening method and screening device of the present invention. The buckled beam is subjected to a lateral force and the three equilibrium positions and the change diagram between the equilibrium positions;

[0035] Figure 2 is a graph showing the relationship between lateral force and lateral displacement under different compression amounts of the present invention;

[0036] Figure 3 is a schematic diagram of the object screening process of the present invention;

[0037] Figure 4 Schematic diagram of the cross-sectional shape of the buckled beam of the present invention

[0038] Figure 5 It is a schematic diagram of the fine thread feeding mechanism and indicator dial of the present invention;

[0039] Figure 6 It is a schematic diagram of the process of objects of the present invention automatically rolling down and screening under the action of gravity;

[0040] Figure 7 It is a three-dimensional model diagram of the parallel arrangement buckled beam screening mechanism of the present invention;

[0041] Figure 8 It is a schematic diagram of the buckled beam screening device of the present invention;

[0042] Figure 9 It is a schematic diagram of the three-dimensional prototype structure of the present invention.

[0043] In the figure, 1, buckling beam; 2, fine-thread screw; 3, adjustment handle; 4, pointer; 5, fixing screw; 6, first fixed long beam; 7, dial; 8, first buckling beam; 9, first partition plate; 10, second buckling beam; 11, second partition plate; 12, third buckling beam; 13, third partition plate; 14, fourth buckling beam; 15, fourth partition plate; 16, fifth buckling beam; 17, fifth partition plate; 18, sixth collection box; 19 , roller; 20, fifth collection box; 21, fourth collection box; 22, third collection box; 23, second collection box; 24, first collection box; 25, locking bolt; 26, lifting adjustment plate; 27, rotating shaft; 28, support plate; 29, parallel arrangement of buckling beam mechanism; 30, guard plate; 31, entrance; 32, base frame; 33, second fixed long beam; 34, long strip through hole; 35, spring; 36, U-shaped plate; 37, semicircular plate. DETAILED DESCRIPTION

[0044] The following will provide a clear and complete description of the relevant technologies in the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0045] refer to Figures 1 to 9 This embodiment is based on the buckled beam vibration theory and designs a buckled beam screening mechanism with both ends fixed.

[0046] 1. Calculation Theory of Object Screening Based on Buckled Beam Vibration

[0047] When one end of a straight beam is fixed, an axial force F is applied to the other end in a direction parallel to the axial direction of the beam. a , when the axial force F a Greater than the critical force P 1j , the straight beam will buckle, and the straight beam will become a buckled beam.

[0048]

[0049] In formula (1), E is the elastic modulus of the material, I is the section moment of inertia of the beam, and l is the distance between the two fixed ends of the beam.

[0050] Buckled beam has three equilibrium positions, namely two stable equilibrium positions A and B and one unstable equilibrium position C. Figure 1 shown. Figure 1 The free length of the beam in l0, Δl c For right, u y is the lateral force F t The lateral displacement of the buckled beam under load.

[0051] When subjected to a lateral force F perpendicular to the beam t When the force acts, the buckled beam rapidly jumps, that is, it jumps from the stable equilibrium position A to the unstable equilibrium position C to the stable equilibrium position B. The time taken to jump from state A to state B is less than 1s.

[0052] According to the first-order vibration mode and potential energy function of the buckled beam, the lateral force F t and lateral deformation u y The relationship is

[0053]

[0054] It can be seen from formula (2) that the lateral force F t and Δl c A is the cross-sectional area of the buckled beam, where A = a × b. Figure 4 As shown, with Δl c The increase of the corresponding lateral force F t Also increases with different Δl c Lower lateral force F t and lateral displacement u y The relationship curve is as follows Figure 2 As shown. When the lateral force F t After replacing it with the weight G of the object to be screened, that is, F t =G, then by adjusting Δl c The magnitude of the lateral force F is controlled by t The size of the object to be screened is adjusted by G.

[0055] 2. Item Screening Process and Weight Level Settings

[0056] The present invention provides five kinds of buckling beam widths, that is, there are five F t —u y The curve is only when the weight G of the object to be screened is greater than or equal to the lateral force F of the buckling beam passing through t When the limit value is reached, the buckled beam and the object can follow the Figure 2 One of the F t —u y Curve action, that is, instantaneous jump phenomenon is realized, and the buckled beam experiences a jump process from stable equilibrium position A, unstable equilibrium position C to stable equilibrium position B. At this time, the buckled beam and the object to be screened jump from the current stable equilibrium position A to the middle position F before the stable equilibrium position B. At this time, the elastic reset device D is compressed to a certain extent, such as Figure 3As shown in the figure, a collection device is installed at equilibrium position F. Objects to be screened fall into the collection device and continue to move toward equilibrium position B under the action of inertia. The reset force generated by the elastic reset device D reaches its maximum value. At this time, the buckled beam immediately returns from equilibrium position B to equilibrium position A under the action of the reset force. This achieves object screening.

[0057] In order to classify the weight of the objects to be screened in more detail, 5 to 10 parallel buckling beams can be set according to actual needs. The following invention takes 5 parallel buckling beams as an example for explanation. The cross-sectional shape of the beam is rectangular, such as Figure 4 According to formula (1), the critical force for the buckling of a straight beam is related to the elastic modulus E of the beam material and the section moment of inertia of the beam. It is related to the distance l between the two fixed ends of the beam. In the present invention, the elastic modulus E of the material and the distance l between the fixed ends are the same, and the beam width parameter a of other buckling beams can be reduced according to a certain ratio, such as a, This achieves the screening weight limit for subsequent other buckled beams.

[0058] In order to realize the visualization of the object weight screening operation, the present invention has designed a fine-thread feed mechanism and a screening weight setting indicator dial. After calibration, the present invention can achieve high-precision weight screening. The fine-thread feed mechanism uses a single-start thread, that is, the pitch of the thread is equal to the lead. Due to the small pitch of the fine thread, it has a self-locking property. When the adjustment handle is turned to any angle, the fine-thread feed mechanism self-locks, ensuring the Δl of the buckled beam. c The fine thread feed mechanism and the screening weight setting indicator dial are as follows: Figure 5 shown.

[0059] Apply an axial force F to the beam a The amount of reduction after Δl c The relationship between the adjustment handle angle θ is as follows:

[0060]

[0061] Where λ is the pitch of the fine thread.

[0062] Example

[0063] Embodiment 1: This embodiment is a filter for a single buckling beam.

[0064] Filters for single buckled beams such as Figure 8As shown, it consists of a frame, a buckling beam 1, and a fine-pitch screw 2. The frame is groove-shaped, with one end of the buckling beam 1 axially fixed to one side of the frame's groove. The other side of the buckling beam 1 is connected to the head of the fine-pitch screw 2 by a rotating shaft. The fine-pitch screw 2 is threadedly connected to the other side of the frame's groove. When the fine-pitch screw 2 rotates, the head of the fine-pitch screw 2 moves back and forth relative to the frame along the axis of the fine-pitch screw 2. When the fine-pitch screw 2 rotates and extends into the interior of the frame, the axial force of the fine-pitch screw 2 squeezes the buckling beam into an upward arch. The adjustment handle 3 and pointer 4 at the end of the fine-pitch screw 2 can be used to directly adjust the magnitude of the jump lateral force of the buckling beam 1 according to the weight to be screened.

[0065] When screening small batches of items, such as agricultural products or industrial products, is required, the operator sets the minimum weight of the items to be screened using the adjustment knob 3 and pointer 4 at the end of the fine-thread screw 2. A single item to be screened is placed on the arched top of the buckling beam 1. When the weight of the item to be screened is less than or equal to the set weight, the gravitational force acting on the buckling beam 1 is less than or equal to the lateral force, and the buckling beam 1 remains stationary without jumping. The item to be screened passes the screening process, and the operator removes the items that have passed the screening process and proceeds to the next round of screening. When the weight of the item to be screened exceeds the set weight, the gravitational force acting on the buckling beam 1 exceeds the lateral force, causing the buckling beam 1 to jump from the upper stable equilibrium position to the lower stable equilibrium position, and the overweight item to be screened is screened out.

[0066] To facilitate placement of objects to be screened and rapid resetting of the buckled beam 1 after a jump, this embodiment further provides an object placement area at the arched top of the buckled beam 1 for rapid placement of objects to be screened, preventing them from slipping or unnecessary displacement. For example, a circular disc or semicircular plate 37 is provided at the arched top of the buckled beam 1. A return spring 35 is provided at the bottom of the frame groove. One end of the spring 35 is fixed to the bottom of the frame groove, while the other end of the spring 35 is suspended and extends upward from the bottom toward the center of the buckled beam 1. In this way, an operator places objects to be screened in the object placement area and observes whether the buckled beam 1 jumps before performing screening. When the weight of the objects to be screened exceeds the lateral force, the buckled beam 1 jumps from the upper stable equilibrium position to the lower stable equilibrium position, compressing the spring 35. After the operator collects the objects to be screened whose weight exceeds the lateral force, the buckled beam 1 jumps back to its original position under the elastic force of the spring 35. The operator can then continue placing objects to be screened in the object placement area, thereby achieving continuous and rapid screening operations.

[0067] This embodiment is suitable for small-batch screening within a single weight range, such as agricultural product screening or rapid sampling of overweight products on an assembly line.

[0068] Embodiment 2: This embodiment is a round block agricultural product screening machine composed of multiple buckling beams.

[0069] Multi-buckling beam combination round block agricultural product screening machine Figure 6 、 7As shown in FIG9 , the connection instructions of the various parts of the round block agricultural product screening machine are as follows:

[0070] The two ends of the first buckling beam 8, the second buckling beam 10, the third buckling beam 12, the fourth buckling beam 14 and the fifth buckling beam 16 are respectively clamped in the first fixed long beam 6 and the second fixed long beam 33, the first partition plate 9, the second partition plate 11, the third partition plate 13, the fourth partition plate 15 and the fifth partition plate 17 are connected to the guard plate 30, the first buckling beam 8, the second buckling beam 10, the third buckling beam 12, the fourth buckling beam 14, the fifth buckling beam 16, the first fixed long beam 6, the second fixed long beam 33, the adjustment handle 3 and the pointer 4 constitute a parallel buckling beam mechanism 29, the upper end of the parallel buckling beam mechanism 29 is connected to the lifting adjustment plate 26 through the rotary shaft 27, and the lower end of the parallel buckling beam mechanism 29 is connected to the base frame 32 through the rotary shaft 27.

[0071] The adjusting handle 3 is fixedly connected to the fine-thread screw 2, and the pointer 4 is connected to the adjusting handle 3. The pointer 4 rotates with the adjusting handle 3. The fine-thread screw 2 is threadedly connected to the first fixed long beam 6. When the fine-thread screw 2 rotates, the fine-thread screw 2 pushes the first buckling beam 8 out to achieve Δl c The fixing screw 5 fixes the dial 7 on the first fixed long beam 6. The dial 7 is marked with scales, and each scale corresponds to a filterable weight (such as kg or g).

[0072] The support plate 28 is connected to the base frame 32 through the rotating shaft 27. An elongated through hole 34 is processed in the lifting adjustment plate 26. The locking bolt 25 slides in the elongated through hole 34. Rotating the locking bolt 25 can apply positive pressure to the lifting adjustment plate 26 and the support plate 28. Under the action of the friction between the two, the lifting adjustment plate 26 is kept stationary on the support plate 28.

[0073] Four rollers 19 are connected to a base frame 32, enabling the movement of this embodiment. The first, second, third, fourth, and fifth collection boxes 24, 23, 22, 21, and 20 are connected to the base frame 32. An inclined plate 35 is mounted within the base frame 32 to facilitate the sliding of screened objects into the respective collection boxes.

[0074] Because the five parallel buckling beams have the same structure, the structure at first buckling beam 8 is used as an example for explanation. One end of spring 35 is fixed to the center of U-shaped plate 36. U-shaped plate 36 is connected to first and second fixed long beams 6, 33 and can rotate together with them about rotation axis 27. Semicircular plate 37 is fixed to first buckling beam 8 to ensure that objects to be screened pass through the center of first buckling beam 8.

[0075] (1) Basic process of object screening

[0076] Taking the first buckling beam 8 as an example, the object screening process is explained. When the weight of an object is greater than or equal to the critical force of first buckling beam 8, first buckling beam 8 begins to move downward from stable position A to unstable equilibrium position C. Due to the tilt of first buckling beam 8, the object begins to slide toward the edge of first buckling beam 8 under the action of gravity. When the object and first buckling beam 8 reach intermediate position F, the object slides off first buckling beam 8 and falls into first collection box 24, completing the screening process. First buckling beam 8 then continues to move downward to stable equilibrium position B, and returns to stable equilibrium position A under the action of spring 35. The screening process for second buckling beams 10 through fifth buckling beams 16 is similar to that for first buckling beam 8.

[0077] Since the widths of the first to fifth buckling beams 8, 16 in this embodiment are arranged from large to small, the screening weights of the first to fifth buckling beams 8, 16 decrease in sequence. When a light object passes through the first buckling beam 8, the lateral critical force value of the first buckling beam 8 cannot be reached, and the object continues to roll downward. When a certain buckling beam critical force value is met, the jump phenomenon of the buckling beam is instantaneously triggered, and the buckling beam bends downward rapidly. Since the buckling beam is tilted, under the action of gravity, the objects to be screened instantly fall into the collection box when passing between the unbalanced position C and the intermediate position F, thereby achieving object weight screening.

[0078] If the object is very heavy, it directly meets the jump condition of the first buckling beam 8 and the object falls directly into the first collection box 24. If the object is very light, it does not meet the jump condition of the five parallel buckling beams and the object rolls directly into the sixth collection box 18.

[0079] (2) Screening weight classification

[0080] a) When the weight of the object is greater than the limit value of the first buckling beam 8, it falls into the first collection box 24;

[0081] b) When the weight of the object is greater than the limited value of the second buckling beam 10 and less than the first buckling beam 8, it falls into the second collection box 23;

[0082] c) When the weight of the object is greater than the limited value of the third buckling beam 12 and less than the second buckling beam 10, it falls into the third collection box 22;

[0083] d) When the weight of the object is greater than the limited value of the fourth buckling beam 14 and less than the third buckling beam 12, it falls into the fourth collection box 21;

[0084] e) When the weight of the object is greater than the limit value of the fifth buckling beam 16 and less than the limit value of the fourth buckling beam 14, it falls into the fifth collection box 20;

[0085] f) When the weight of the object is less than the limit value of the fifth buckling beam 16, it falls into the sixth collection box 18;

[0086] (3) Adjustment of screening weight for each buckling beam

[0087] The fine-pitch screw 2 adopts a right-hand thread. When the adjustment handle 3 is rotated clockwise, the fixed long beam a remains stationary, and the fine-pitch screw 2 screws in, thereby pushing and increasing the deformation of the buckled beam 1. According to equations (2) and (3), the minimum weight that can be screened can be calculated, that is, the increase adjustment of the screening weight is realized.

[0088] (4) Adjustment of the rolling speed of the screening objects

[0089] The sizes and weights of the objects to be screened vary. Under the action of weight, the rolling speeds of the objects passing through the screening device of this embodiment are also different. In order to adapt to actual screening requirements, this embodiment provides an inclination adjustment device for the buckling beam screening overall mechanism. First, loosen the locking bolt 25, manually raise / lower the parallel buckling beam mechanism 29 to the required position, and then tighten the locking bolt 25 to adjust the inclination angle Φ of the parallel buckling beam mechanism 29, thereby adjusting the roller speed of the object.

[0090] In summary, the present invention is based on the buckled beam vibration theory, according to the geometric dimensions of the beam and the reduction amount Δl c The minimum weight of the object that can be screened out by each column of buckled beams can be directly and accurately obtained; in addition, the Δl of this column can also be c Adjustment is performed to achieve stepless adjustment of the screening weight of this column of buckling beams, so that the objects to be screened can automatically roll down and be screened and classified.

[0091] It should be emphasized that the above are only preferred embodiments of the present invention and do not limit the present invention in any form. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A buckled beam gravity screening method, characterized in that: The following steps are involved: Step 1: Fix one end of the straight beam axially, and apply an axial force inwardly along the other end of the straight beam so that the axial force exceeds a critical force, causing the straight beam to buckle and become a buckled beam, wherein the buckled beam has at least an upper stable equilibrium position and a lower stable equilibrium position; Step 2: by adjusting the reduction amount of the axial distance of the buckled beam and / or the geometric dimensions of the buckled beam, the magnitude of the lateral force that can cause the buckled beam to produce a sudden change in lateral displacement is set; Step 3: adjusting the buckled beam to the upper stable equilibrium position; Step 4: Allow the object to be screened to pass through the stable equilibrium position on the buckling beam under its own weight; Step 5: Objects to be screened whose deadweight is greater than the lateral force are subjected to gravity, causing the buckling beam to jump to the lower stable equilibrium position and be screened out; objects to be screened whose deadweight is less than or equal to the lateral force are screened by the buckling beam.

2. The buckled beam gravity screening method according to claim 1, characterized in that: In step 2, the magnitude of the lateral force is: In formula (2), F t represents the lateral force, A represents the cross-sectional area of the buckled beam, E represents the elastic modulus of the buckled beam material, I represents the section moment of inertia of the buckled beam, l represents the distance between the two ends of the buckled beam, and u represents the cross-sectional area of the buckled beam. y represents the lateral displacement of the buckled beam under the action of lateral force, l0 represents the free length of the straight beam, Δl c Indicates the reduction in axial distance of the buckled beam.

3. The buckled beam gravity screening method according to claim 2, characterized in that: In step 2, the axial distance reduction of the buckled beam is adjusted by fine thread. c , the relationship between the reduction in the axial distance of the buckled beam and the fine thread is: In formula (3), λ represents the pitch of the fine thread, and θ represents the rotation angle of the fine thread.

4. The buckled beam gravity screening method according to claim 1, characterized in that: In step 5, a buckling beam reset mechanism is provided at the lower stable equilibrium position so that when the object to be screened leaves the buckling beam, the buckling beam jumps and resets again to return to the upper stable equilibrium position.

5. The buckled beam gravity screening method according to claim 1, characterized in that: A plurality of buckling beams are provided, and the plurality of buckling beams are provided with a plurality of lateral forces of different sizes, so that the objects to be screened pass through the stable equilibrium positions on different buckling beams in sequence by their own weight, thereby completing the screening of objects to be screened within different weight ranges.

6. A buckling beam gravity screening device, characterized in that: The screening device adopts the screening method according to any one of claims 1 to 5, and the screening device comprises: a buckling beam (1), an axial force regulating device, one end of the buckling beam (1) is fixed in the axial direction, the other end of the buckling beam (1) is fixedly connected to the axial telescopic end of the axial force regulating device, and the fixing portion of the axial force regulating device is fixed; After the axial distance adjustment of the axial force adjustment device is completed, the buckling beam (1) has an arched upper stable equilibrium position and a lower stable equilibrium position; A screening channel is provided in the middle of the upper surface of the buckling beam (1).

7. The buckled beam gravity screening device according to claim 6, characterized in that: A reset device is provided in the middle of the lower surface of the buckled beam (1), and the reset device is used to reset the buckled beam (1) to jump back to the upper stable equilibrium position when the buckled beam (1) jumps to the lower stable equilibrium position.

8. The buckled beam gravity screening device according to claim 6, characterized in that: The axial force adjustment device is a threaded connection device, the threaded connection device is provided with an adjustment handle (3) linked to the axial telescopic end of the threaded connection device, the adjustment handle (3) is provided with a pointer (4), the fixed portion of the threaded connection device is provided with a dial (7), and the pointer (4) points to the scale on the dial (7).

9. The buckled beam gravity screening device according to claim 6, characterized in that: A recovery device is provided at the lower stable equilibrium position of the buckling beam (1).

10. The buckled beam gravity screening device according to claim 6, characterized in that: A plurality of the buckling beams (1) are provided, and the plurality of the buckling beams (1) are arranged in sequence along the length direction of the screening channel, and the lateral forces of the plurality of the buckling beams (1) are arranged in sequence from large to small along the length direction of the screening channel.

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