Ultrafine powder high-efficiency screening device

Abstract

The application discloses a kind of ultrafine powder high-efficiency screening equipment, belongs to ultrafine powder screening technical field, including box, the top front end of the box is fixedly installed with feed hopper, and the side of box is installed with several supporting legs by elastic connecting seat one, the box inside and outside are jointly provided with the sieving mechanism for screening ultrafine powder;The application is by being provided with the multilayer sieve plate of inclined wave shape and mass, wave height wave distance gradient change, and is matched with the elastic connecting seat of distinguishing natural frequency, and the differential vibration response of each layer sieve plate is converted to the whole strong vibration of box, wave shape structure is while increasing effective screening area, utilizes ups and downs change to promote powder layer loose rearrangement, and the strong throwing effect of upper layer large mass sieve surface realizes quick dispersion and coarse powder discharge, and the sieve surface of lower layer small mass is extended by increasing screening area to extend fine powder screening time and reduce dust raising, and the problems of agglomeration, blockage, poor grading accuracy and dust raising are solved simultaneously under the condition of single excitation source.

Description

Technical Field

[0001] This invention relates to the field of ultrafine powder screening technology, specifically to an efficient ultrafine powder screening device. Background Technology

[0002] Ultrafine powders typically refer to powder materials with particle sizes in the micrometer or even nanometer range. Due to their characteristics such as large specific surface area, high surface activity, poor flowability, and easy agglomeration, they have wide applications in chemical, metallurgical, pharmaceutical, electronic, and new material preparation fields. In the chemical field, the particle size uniformity of ultrafine catalyst powders directly affects the selectivity and conversion rate of catalytic reactions. In the pharmaceutical field, the particle size distribution of inhaled drug powders determines the deposition site and absorption efficiency of drugs in the lungs. In the field of electronic materials, the dispersibility and particle size consistency of powders in ultrafine conductive pastes are directly related to conductivity and device reliability.

[0003] As downstream industries place increasingly stringent requirements on the uniformity and purity of product particle size distribution, precise classification of ultrafine powders has become a key step in improving product quality. However, due to their small particle size, large specific surface area, and significant interparticle forces, ultrafine powders are prone to agglomeration, adhesion, and clogging of sieve holes during the screening process, making screening much more difficult than for conventional powders. Ultrafine powder screening equipment is the core equipment used to effectively separate ultrafine powders of different particle sizes. Its classification accuracy and processing efficiency directly affect the stability of subsequent processes and the performance of the final product.

[0004] In existing ultrafine powder screening equipment, multi-layer planar screens arranged vertically are typically used to achieve multi-stage particle size classification. However, such equipment has significant technical drawbacks in practical applications: First, during vibratory screening, the powder layer moves in a two-dimensional plane on the screen surface, resulting in a lack of effective separation gradient between coarse and fine particles in the horizontal direction. Fine powder, covered by coarse powder, is difficult to reach the screen surface, leading to low screening efficiency. Second, each layer of screen is usually designed with the same material thickness and a gradient-varying mesh size, without considering the differences in powder load and required motion characteristics between layers. Under overall vibration conditions, the upper layer of coarse powder, due to its large mass and poor flowability, will carry fine powder, requiring a larger vibration force to effectively disperse it. Meanwhile, the lower layer of fine powder is prone to excessive jumping and dust generation under the same strong vibration. Neither layer can obtain a vibration response that matches its screening requirements, resulting in poor classification accuracy and severe coarse-fine powder entrainment, significantly limiting the continuous and stable operation capability of the equipment. Summary of the Invention

[0005] The purpose of this invention is to provide an efficient screening device for ultrafine powders to solve the problems in the prior art, such as insufficient separation gradient of coarse and fine particles caused by multi-layer planar screens, inability of each layer of screens to obtain differentiated vibration response, resulting in poor classification accuracy, serious coarse powder mixed with fine powder, and easy dust generation of fine powder in the lower layer.

[0006] The technical problem to be solved by the present invention can be achieved by the following technical solution: including a box body, wherein a feeding hopper is fixedly installed at the front end of the top of the box body, and a number of support legs are installed on the side of the box body through an elastic connecting seat; and a sieving mechanism for sieving ultrafine powder is provided both inside and outside the box body. The sieving mechanism includes multiple sieve plates installed inside the housing and inclined to the lower right. The sieve plates are wavy and have several sieve holes for discharging powder. The diameter of the sieve holes on the multiple sieve plates gradually decreases from top to bottom, and the mass of the multiple sieve plates increases layer by layer from top to bottom. The wave height and wave pitch of the sieve plates are positively correlated with the mass of the sieve plates. Side mounting plates are fixedly connected to the left and right sides of the sieve plates, and the side mounting plates are connected to the inside of the housing through elastic connecting seats. It also includes a high-vibration assembly installed at the bottom of the enclosure, which is used to drive the enclosure to vibrate; The rear end of the box is provided with a discharge component that is connected to each of the screen plates.

[0007] Preferably, both the first elastic connecting seat and the second elastic connecting seat are composite springs, and the natural frequency of the second elastic connecting seat is higher than that of the first elastic connecting seat.

[0008] Preferably, the strong vibration assembly includes an exciter body fixedly installed on the front side of the bottom of the housing. The excitation shaft of the exciter body passes through the side wall of the housing and is fixedly connected to the output end of the drive component through a flexible coupling. The drive component is fixedly installed on the ground by a support.

[0009] Preferably, the sieving mechanism further includes micro-vibration components disposed on the left and right side walls of the housing, which are used to drive the sieve plate to generate longitudinal vibration.

[0010] Preferably, the micro-vibration assembly includes several vibration coils that are equidistantly fixed to the outside of the side plate. The outside of the vibration coils is fixedly connected to the transmission shaft through an elastic connecting ring. The transmission shaft passes through the side wall of the box and extends to the outside of the box. All transmission shafts on the same side of the sieve plate are fixedly connected to the transmission plate. The transmission plate is distributed parallel to the side plate. The transmission plate is installed on the side wall of the box through several connecting frames. An ultrasonic transducer is also installed on the transmission plate. The ultrasonic transducer is electrically connected to an ultrasonic generator.

[0011] Preferably, a resonance avoidance structure is provided between the strong vibration component and the micro vibration component. The resonance avoidance structure includes an elastic vibration isolation sleeve sleeved on the transmission shaft. The elastic vibration isolation sleeve penetrates through the side wall of the fixed box. The resonance avoidance structure also includes an elastic vibration isolation pad. Elastic vibration isolation pads are provided between the connecting frame and the transmission plate and between the connecting frame and the side wall of the box. The elastic vibration isolation sleeve and the elastic vibration isolation pad are made of rubber.

[0012] Preferably, the resonant avoidance structure further includes a high-frequency vibration component whose operating frequency is offset from that of the low-frequency vibration component; The micro-vibration components corresponding to two adjacent sieve plates are 120° out of phase in the driving signal phase.

[0013] Preferably, the discharge component includes a sliding plate flush with the sieve plate and fixedly connected to the rear side of the box. The sliding plate and the sieve plate are fixedly connected by a flexible connecting strip. A sealing plate is fixedly connected between the rear side of the upper wall and the lower inclined wall of the box. The sealing plate is set in two sets and vertically penetrates and fixes each layer of sliding plate. A space for storing powder is left between the two sets of sealing plates. Each layer of sliding plate is provided with a corresponding discharge port. Each discharge port is provided with a valve body structure. The valve body structure is divided into an inner valve and an outer valve. The two have the same structure. A valve body structure is also provided in the feed hopper to control the feeding process.

[0014] Preferably, the valve body structure includes a valve plate, a sealing plate, and a valve plate rotatably mounted in the feed hopper via a pivot pin. Limiting steps are provided at the contact positions between the sealing plate and the valve plate, as well as between the side wall of the feed hopper and the valve plate. A torsion spring is installed on the pivot pin, and the surface of the valve plate is covered with a sealing silicone layer.

[0015] Preferably, the outside of the pivot pin is provided with a drive component for driving its rotation, and the drive component is a pneumatic actuator.

[0016] Compared with the prior art, the beneficial effects of this application are as follows: 1. This invention uses a multi-layered sieve plate with an inclined wave shape and gradient changes in mass, wave height, and wave distance, along with elastic connecting seats that differentiate natural frequencies. This transforms the overall strong vibration of the box into differentiated vibration responses of each sieve plate. The wave-shaped structure increases the effective screening area while promoting the loosening and rearrangement of powder layers through undulation. The upper high-mass sieve surface achieves rapid dispersion and coarse powder discharge through strong throwing action, while the lower low-mass sieve surface extends the screening time of fine powder and reduces dust by increasing the screening area. At the same time, the fine wave shape also enhances the structural strength of the lower low-mass sieve. Under a single excitation source, this invention simultaneously solves the problems of agglomeration and blockage, poor classification accuracy, and dust.

[0017] 2. In this invention, the natural frequency of the second elastic connecting seat is designed to be 3 to 5 times that of the first elastic connecting seat. When the box resonates and amplifies low-frequency vibration, the second elastic connecting seat forms a vibration isolation barrier, which allows the low-frequency high-amplitude vibration to be smoothly transmitted to the sieve plate. At the same time, it absorbs and blocks high-frequency noise, ensuring that the sieve plate only follows the stable low-frequency vibration to make regular throwing motion, avoiding disorderly jumping and ensuring the orderly movement of powder.

[0018] 3. In this invention, the crests and troughs of the corrugated sieve plate extend along the inclined direction. During the process of climbing down the slope, the powder is loosened and rearranged, which effectively destroys the bridging structure and promotes the separation and sieving of fine powder. Moreover, the slope is less than the slope of the sieve surface, so that the powder maintains a downward trend and avoids a large amount of deposition. At the same time, the wave height and wave distance increase synchronously with the mass of the sieve plate, so that the upper sieve plate has sufficient undulation and drop, preventing coarse particles from depositing in the trough and forming dead zones. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall three-dimensional structure of the present invention; Figure 2 This is a schematic diagram of the left-side structure of the present invention; Figure 3 This is a schematic diagram of the left-side cross-sectional structure of the present invention; Figure 4 This is a schematic diagram of the three-dimensional connection structure of the sieve plate and the micro-vibration component of the present invention; Figure 5 This is a three-dimensional structural diagram of the discharge component of the present invention; Figure 6 This is a cross-sectional view of the valve body structure of the present invention; Figure 7 This is a three-dimensional structural diagram of the sieve plate of the present invention; Figure 8 This is a three-dimensional structural diagram of the micro-vibration component of the present invention.

[0020] Explanation of reference numerals in the attached figures: 1. Housing; 2. Support legs; 21. Elastic connecting seat one; 3. Strong vibration assembly; 31. Vibrator body; 32. Flexible coupling; 33. Drive component; 331. Support; 4. Feed hopper; 5. Micro-vibration assembly; 51. Ultrasonic transducer; 52. Vibration plate; 53. Vibration ring; 54. Elastic connecting ring; 55. Vibration shaft; 56. Elastic vibration isolation sleeve; 57. Connecting frame; 6. Screen plate; 61. Side mounting plate; 62. Elastic connecting seat two; 63. Screen hole; 7. Discharge component; 71. Flexible connecting belt; 72. Sealing plate; 73. Sliding plate; 8. Valve body structure; 81. Valve plate; 82. Sealing silicone layer; 83. Turning pin; 84. Torsion spring; 85. Limiting step. Detailed Implementation

[0021] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0022] Example 1 Understandably, in existing ultrafine powder screening equipment, multi-layer planar screens arranged vertically are typically used to achieve multi-stage particle size classification. However, such equipment has significant technical drawbacks in practical applications: First, during vibratory screening, the powder layer on the screen surface moves in a two-dimensional plane, resulting in a lack of effective separation gradient between coarse and fine particles in the horizontal direction. Fine powder, covered by coarse powder, is difficult to reach the screen surface, leading to low screening efficiency. Second, each layer of screen is usually designed with the same material thickness and a gradient-varying mesh size, without considering the differences in powder load and required motion characteristics between layers. Under overall vibration conditions, the upper layer of coarse powder, due to its large mass and poor flowability, requires a greater vibration force to be effectively dispersed, while the lower layer of fine powder is prone to excessive jumping and dust generation under the same strong vibration. Neither layer can obtain a vibration response that matches its screening requirements, resulting in poor classification accuracy and severe coarse-fine powder entrainment, significantly limiting the continuous and stable operation capability of the equipment.

[0023] like Figures 1 to 8 In this embodiment, a box body 1 is included. A feeding hopper 4 is fixedly installed at the top front end of the box body 1. Several support legs 2 are installed on the side of the box body 1 through an elastic connecting seat 21. A sieving mechanism for screening ultrafine powder is provided both inside and outside the box body 1. The sieving mechanism includes multiple sieve plates 6 installed inside the housing 1 and inclined to the lower right. The sieve plates 6 are wavy and have a number of sieve holes 63 for discharging powder. The diameter of the sieve holes 63 of the multiple sieve plates 6 gradually decreases from top to bottom, and the mass of the multiple sieve plates 6 increases layer by layer from top to bottom. The wave height and wave pitch of the wavy sieve plates 6 are positively correlated with the mass of the sieve plates 6. Side mounting plates 61 are fixedly connected to the left and right sides of the sieve plates 6. The side mounting plates 61 are connected to the inside of the housing 1 through elastic connecting seats 62. It also includes a strong vibration assembly 3 installed at the bottom of the housing 1, which is used to drive the housing 1 to vibrate; The rear end of the box body 1 is provided with a discharge component 7 that is connected to each of the screen plates 6.

[0024] Both the elastic connecting seat 1 21 and the elastic connecting seat 2 62 are composite springs, and the natural frequency of the elastic connecting seat 2 62 is higher than that of the elastic connecting seat 1 21 (approximately 3-5 times).

[0025] The strong vibration assembly 3 includes an exciter body 31 fixedly installed on the front side of the bottom of the housing 1. The excitation shaft of the exciter body 31 passes through the side wall of the housing 1 and is fixedly connected to the output end of the drive component 33 through a flexible coupling 32. The drive component 33 is fixedly installed on the ground through a support 331.

[0026] Working principle of the strong vibration component 3: The driving component 33 drives the vibrator body 31 to run through the flexible coupling 32, generating periodic excitation force. The driving component 33 is a servo motor. Since the housing 1 is installed on the support leg 2 through the elastic connecting seat 21, the housing 1 as a whole generates large-scale low-frequency vibration at a low natural frequency. This vibration is transmitted to each layer of screen plate 6 almost rigidly through the elastic connecting seat 62. Since the mass of multiple sieve plates 6 increases from top to bottom, and the aperture of sieve holes 63 gradually decreases from top to bottom, the wave height and wave distance of the sieve plate 6 are positively correlated with the mass of the sieve plate 6. That is, the upper sieve plate 6 has the smallest mass and the smallest wave height and wave distance, while the lower sieve plate 6 has the largest mass and the largest wave height and wave distance. Under the same excitation conditions in box 1, the upper small-mass screen plate 6, due to its low inertia and good following ability, obtains a large response amplitude. Combined with its small undulating wave-shaped structure, coarse powder is subjected to high-frequency throwing on the screen surface, and the powder clumps are quickly loosened. The coarse particles move rapidly towards the end discharge part 7 and are discharged through large-amplitude jumping. At the same time, the small wave height structure has less resistance to the movement of coarse powder, which is conducive to the smooth discharge of coarse particles. The lower large-mass screen plate 6, due to its high inertia, has a relatively gentle response amplitude, and the throwing force on the screen surface is weakened, which effectively suppresses fine powder dust. Moreover, its wave height and wave distance are the largest. During the movement, the powder needs to repeatedly experience large-amplitude climbing and falling micro-processes. This undulating terrain significantly increases the flow time of fine powder and greatly slows down the downward speed of fine powder, thereby providing sufficient contact time for fine powder to pass through the fine screen holes 63 and effectively improving the screening rate.

[0027] It should be emphasized that the core improvement of this embodiment lies in the following: by setting up a multi-layered sieve plate 6 with an inclined wave shape and gradient changes in mass, wave height and wave pitch, and in conjunction with elastic connecting seat 1 21 and elastic connecting seat 2 62 that distinguish the inherent frequencies, the overall strong vibration of the box 1 is transformed into differentiated vibration responses of each layer of sieve plate 6. The wave-shaped structure increases the effective screening area while using its undulating terrain to promote the loosening and rearrangement of powder layers. The upper layer of lightweight small wave sieve surface achieves rapid powder dispersion and coarse powder discharge through high-frequency throwing action; the lower layer of heavy large wave sieve surface significantly slows down the movement speed of fine powder through the deep valley slowing action, prolongs the screening time of fine powder and reduces dust. The design that the wave height and wave pitch increase synchronously with the mass of the sieve plate 6 makes the undulating drop of the lower layer of sieve plate 6 with larger mass large, in order to meet the need to slow down the movement speed of powder during fine screening and avoid fine powder losing the opportunity to pass through the sieve due to excessive flow rate. Under the condition of a single excitation source, the overall structure simultaneously solves the problems of easy agglomeration and clogging of ultrafine powder, insufficient classification accuracy of multi-layer screens, and excessive dust generation of fine powder in the lower layer, significantly improving screening efficiency and finished product quality.

[0028] It should be noted that, such as Figure 4 and Figure 7In the design of the wavy structure of the sieve plate 6, the arrangement of its crests and troughs extends along the inclined direction of the sieve surface. This allows the powder to repeatedly experience the micro-process of climbing and falling as it moves forward with the vibration of the sieve surface. Moreover, the slope of the climb is less than the slope of the sieve surface. Under the action of gravity, the powder will maintain the downward trend and will not have a large amount of sedimentation. During the micro-process of climbing and falling, the powder layer is locally loosened and rearranged, which effectively destroys the bridging structure between powders and promotes the separation of fine powder from the powder layer and its passage through the sieve holes 63. The wavy structure effectively increases the effective screening area under the same projected area, and at the same time, it can also play a role in structural reinforcement to prevent excessive bending deformation during vibration.

[0029] It should be noted that the natural frequency of the second elastic connector 62 is designed to be 3 to 5 times that of the first elastic connector 21. This is significant because the operating frequency of the strong vibration component 3 is usually close to the natural frequency of the first elastic connector 21, allowing the entire housing 1 to generate a resonant amplification effect and obtain sufficient vibration amplitude to propel the powder forward. At this frequency, the second elastic connector 62, due to its natural frequency being much higher than the operating frequency, exhibits high dynamic stiffness characteristics, equivalent to a rigid connection. This ensures that the main vibration energy of the housing 1 is efficiently and synchronously transmitted to each layer of sieve plates 6, enabling each sieve plate to obtain a consistent and stable motion phase. Simultaneously, its natural frequency is much higher than the operating frequency, preventing itself from experiencing resonant instability, ensuring that the throwing trajectory of the sieve plates 6 is regular and controllable, and preventing disordered jumping of the sieve surface. This ensures that the powder travels orderly along the set direction on each layer of sieve plates 6.

[0030] Example 2 It is understandable that in Embodiment 1, although the overall strong vibration of the housing 1 combined with the gradient wave screen plate 6 achieves grading and screening, the vibrator body 31 generates low-frequency, high-amplitude vibration. Its main function is to drive the powder to move and stratify along the screen surface. For ultrafine powder particles that are already embedded in the screen holes 63 or stuck at the corners of the wave troughs of the wave-shaped screen surface, the low-frequency, high-amplitude strong vibration is difficult to provide enough high-frequency acceleration to break the adhesion or mechanical interlocking force between them and the wall of the screen holes 63. Especially when the humidity of the screening environment is high or the powder is static, the fine powder is very likely to agglomerate and block around the screen holes 63. Relying solely on external strong vibration cannot effectively remove these blockage particles. Long-term operation will lead to a continuous reduction in the effective screening area and a sharp decline in screening efficiency, which seriously restricts the continuous operation capability of the equipment.

[0031] like Figure 4 and Figure 8 To solve the above problems, the sieving mechanism also includes micro-vibration components 5 disposed on the left and right side walls of the housing 1. The micro-vibration components 5 are used to drive the sieve plate 6 to generate longitudinal vibration.

[0032] The micro-vibration assembly 5 includes several vibration coils 53 that are equidistantly fixedly connected to the outside of the side plate 61. The outside of the vibration coils 53 is fixedly connected to the transmission shaft 55 through the elastic connecting ring 54. The transmission shaft 55 passes through the side wall of the box 1 and extends to the outside of the box 1. The transmission shafts 55 on the same side of the sieve plate 6 are all fixedly connected to the transmission plate 52. The transmission plate 52 is distributed parallel to the side plate 61. The transmission plate 52 is installed on the side wall of the box 1 through several connecting brackets 57. An ultrasonic transducer 51 is also installed on the transmission plate 52. The ultrasonic transducer 51 is electrically connected to an ultrasonic generator (the ultrasonic generator is not shown in the figure).

[0033] A resonance avoidance structure is provided between the strong vibration component 3 and the micro vibration component 5. The resonance avoidance structure includes an elastic vibration isolation sleeve 56 sleeved on the transmission shaft 55. The elastic vibration isolation sleeve 56 penetrates the side wall of the fixed housing 1. The resonance avoidance structure also includes an elastic vibration isolation pad. Elastic vibration isolation pads are provided between the connecting frame 57 and the transmission plate 52, and between the connecting frame 57 and the side wall of the housing 1. The elastic vibration isolation sleeve 56 and the elastic vibration isolation pad are made of rubber.

[0034] The resonant avoidance structure also includes a strong vibration component 3 whose operating frequency is set to be offset from that of the micro vibration component 5; The micro-vibration components 5 corresponding to the two adjacent sieve plates 6 are 120° out of phase in the driving signal phase.

[0035] Working principle of micro-vibration component 5: as follows Figure 4 , Figure 7 and Figure 8 The ultrasonic generator produces a high-frequency electrical signal to drive the ultrasonic transducer 51, converting electrical energy into longitudinal high-frequency mechanical vibration of the same frequency. This vibration is distributed to each transmission shaft 55 via the vibration plate 52, and then transmitted to the side mounting plate 61 through the elastic connecting ring 54 and the vibrating coil 53. Finally, it excites the screen plate 6 to generate high-frequency micro-amplitude vibration along the normal direction of the screen surface. This high-frequency micro-vibration is superimposed on the low-frequency high-amplitude vibration generated by the strong vibration component 3, so that the screen surface is in a composite motion state of "low-frequency throwing and high-frequency disturbance". This is effective for removing the blockage in the screen hole 6. The particles in 3 can be accelerated by high-frequency micro-vibration to tens of times the acceleration of gravity, which is sufficient to overcome the friction and adhesion between the particles and the wall of the sieve hole 63, and eject them from the sieve hole 63 to achieve self-cleaning. At the same time, the micro-vibration components 5 corresponding to the two adjacent sieve plates 6 are 120° out of phase in the driving signal, so that the high-frequency micro-vibration of each sieve plate 6 alternates and staggers in time, avoiding harmful coupling of the vibration of each sieve plate 6 through the box 1 or the side plate 61, and ensuring that the micro-vibration effect of each sieve plate 6 is independent and uniform.

[0036] It should be emphasized that the core improvement of this embodiment lies in the introduction of an independent high-frequency micro-vibration component 5 on the basis of the low-frequency high-amplitude vibration provided by the strong vibration component 3. The high-frequency vibration of the ultrasonic transducer 51 is directly fed to each layer of the corrugated screen plate 6 through the transmission shaft 55 and the vibration ring 53, so that the screen surface obtains a composite vibration mode of low-frequency throwing and high-frequency disturbance and hole clearing. This solves the problem of adhesion and blockage of ultrafine powder in the screen hole 63 from a physical level. At the same time, by setting a resonant avoidance structure including an elastic vibration isolation sleeve 56, an elastic vibration isolation pad and a phase difference configuration, the frequency domain and time domain decoupling of the two systems of strong vibration and micro-vibration is realized, ensuring that the two do not interfere with each other and work together, significantly improving the screening stability and effective throughput of the equipment under long-term continuous operation.

[0037] It should be noted that the elastic vibration isolation sleeve 56 adopts an inflatable rubber shock absorber, the internal pressure of which can be adjusted according to the actual working conditions. By changing the internal pressure of the airbag, its stiffness and damping characteristics can be adjusted. While ensuring that the axial high-frequency vibration of the transmission shaft 55 is effectively transmitted to the side plate 61, it effectively blocks the low-frequency large-amplitude vibration of the housing 1 from being transmitted radially in the opposite direction to the transmission shaft 55 and the ultrasonic transducer 51. This avoids the low-frequency strong vibration of the exciter body 31 from damaging the piezoelectric ceramic element inside the ultrasonic transducer 51. The elastic vibration isolation pad cuts off the low-frequency vibration transmission path between the connecting frame 57 and the transmission plate 52, preventing the vibration of the housing 1 from bypassing the high-frequency vibration mode of the transmission plate 52 through the connecting frame 57.

[0038] It should be noted that the 120° phase difference between the micro-vibrations of adjacent sieve plates 6 is designed with the following motivation: each sieve plate 6 is driven by the same ultrasonic generator through its own transmission shaft 55. If all sieve plates 6 simultaneously perform longitudinal high-frequency micro-vibrations with the same phase, then each sieve plate 6 will be in sync with the vibration direction. At this time, all sieve plates 6 and the powder they carry will move upward or downward at the same time, which is very easy to excite the longitudinal resonance of the entire sieve plate 6 system, resulting in abnormal amplification of the vibration amplitude. This may not only damage the structure of the sieve plate 6, but also cause the micro-vibration cleaning effect of the sieve surface to drop significantly due to resonance instability. With a 120° phase difference, the longitudinal micro-vibrations of each sieve plate 6 are staggered in time, and the resultant force of the overall vibration tends to be dispersed rather than superimposed at any given moment, thereby effectively destroying the conditions for resonance formation, allowing each sieve plate 6 to independently and stably maintain its designed amplitude, and ensuring that the micro-vibration cleaning effect is uniformly and reliably performed in each layer.

[0039] In this embodiment, the vibration ring 53 adopts a structure in which an annular metal ring is covered with wear-resistant rubber. In addition to the elastic vibration isolation sleeve 56, a labyrinth sealing structure is also provided between the transmission shaft 55 and the side wall of the box 1 to prevent powder from leaking to the outside of the box 1 along the gap of the transmission shaft 55. The ultrasonic transducer 51 is preferably a piezoelectric transducer, and its resonant frequency is at least 5kHz different from the in-plane natural frequency of the sieve plate 6 to avoid high-frequency fatigue damage to the sieve plate 6 itself.

[0040] Example 3 Understandably, in Example 2, although the combined effect of strong vibration and micro vibration effectively ensured the screening efficiency and alleviated the clogging problem of sieve holes 63, the ultrafine powder has a very large specific surface area and high surface energy, and is very easy to suspend in the air and form aerosols under vibration. In this solution, a multi-layer sieve plate 6 is used for grading, and correspondingly, multiple stacked discharge ports need to be set on the rear side of the box 1 to achieve independent discharge of powders of different particle sizes. The number of discharge ports is large, and each outlet has the risk of dust emission under vibration.

[0041] Traditional equipment often uses a single valve plate 81 structure at these discharge ports. While this provides some isolation when the valve is closed, during the discharge process, the channel formed by the rotation of the valve plate 81 directly connects the interior of the housing 1 with the external environment. Fine powder suspended inside the housing 1, under the combined action of vibration and airflow, continuously sprays outward along the open valve. This is especially problematic when multiple discharge ports are discharging sequentially; each opening stage becomes a window for dust leakage, and a single valve is insufficient to achieve a seal during dynamic discharge. Furthermore, the feed hopper 4 also suffers from powder backflow and dust generation during feeding. Existing equipment lacks a comprehensive sealed feeding and discharging solution for multi-layer discharge structures under vibration conditions.

[0042] like Figure 3 , Figure 5 and Figure 6 To solve the above problems, the discharge component 7 includes a sliding plate 73 that is flush with the screen plate 6 and fixedly connected to the rear side of the inside of the box 1. The sliding plate 73 and the screen plate 6 are fixedly connected by a flexible connecting strip 71. A sealing plate 72 is fixedly connected between the rear side of the upper wall and the lower inclined wall of the box 1. The sealing plate 72 is set in two sets and vertically penetrates and fixes each layer of sliding plate 73. Each layer of sliding plate 73 is provided with a corresponding discharge port. Each discharge port is provided with a valve body structure 8. The valve body structure 8 is divided into an inner valve and an outer valve. The two have the same structure. The feed hopper 4 is also provided with a valve body structure 8 to control the feeding process.

[0043] The valve body structure 8 includes a valve plate 81, a sealing plate 72, and a valve plate 81 rotatably mounted in the feed hopper 4 via a pivot pin 83. Limiting steps 85 are provided at the positions where the sealing plate 72 contacts the valve plate 81 and the side wall of the feed hopper 4 contacts the valve plate 81. A torsion spring 84 is installed on the pivot pin 83, and a sealing silicone layer 82 is covered on the surface of the valve plate 81.

[0044] The pivot pin 83 is externally provided with a drive component for driving its rotation, which is a pneumatic actuator.

[0045] Working principle of valve body structure 8: as follows Figure 3 , Figure 5 and Figure 6Taking the feeding process as an example, in the initial state, the valve plates 81 of the inner valve and the outer valve are tightly attached to the limiting step 85 under the pre-tightening force of the torsion spring 84, keeping them closed and sealed. When feeding, the pneumatic actuator on the outer valve first drives its valve plate 81 to rotate and open against the force of the torsion spring 84. The powder falls from the feed hopper 4 into the buffer space between the inner valve and the outer valve. Then the outer valve closes, forming a sealed intermediate material cavity, blocking the connection between the external airflow and the inside of the box 1. Then the pneumatic actuator on the inner valve drives its valve plate 81 to open. The powder falls into the inside of the box 1 by gravity. The inner valve then closes, completing one sealed feeding cycle. Reverse operation during discharge: First, open the inner valve at the discharge port. The powder that has been classified in the box 1 falls into the buffer chamber between the inner valve and the outer valve. After the inner valve is closed, open the outer valve to discharge the powder to the external collection container. Throughout the process, the inside of the box 1 is always isolated from the external atmosphere. When the valve plate 81 is closed, it achieves a reliable seal through the dual action of the torsion spring 84 and the limiting step 85. The discharge sequence is carried out layer by layer from top to bottom. That is, first open the outer valve of the uppermost coarse powder discharge port to discharge the coarse powder, and then open the outer valves of the medium and fine powder discharge ports in sequence to ensure that powders of different particle sizes are not mixed.

[0046] It should be emphasized that the core improvement of this embodiment lies in the following: a dual valve body structure 8 consisting of an inner valve and an outer valve is installed at the feed hopper 4 and the numerous discharge ports at each layer. With the timing control of the pneumatic actuator, under the condition of continuous operation of the vibrating screening equipment, the entire feeding and discharging process is closed through the regular operation of the outer valve opening buffer, the outer valve closing isolation, the inner valve opening release, and the inner valve closing sealing. This structure uses the limiting step 85 and the torsion spring 84 to ensure the dynamic sealing reliability of the valve plate 81 under vibration conditions, fundamentally blocking the path of ultrafine powder to escape into the workshop environment along the feed and discharge channels under vibration excitation, and solving the problems of material loss and occupational health hazards caused by powder diffusion.

[0047] It should be noted that the design of the limiting step 85 not only serves as a mechanical stop when the valve plate 81 is closed, but also has an elastic sealing strip embedded on its step surface. When the valve plate 81 is pressed to the limiting step 85 under the action of the torsion spring 84, the elastic sealing strip is compressed to form a surface contact sealing pair, which can withstand the pressure pulsation within ±5kPa caused by vibration inside the housing 1 without leakage. The use of the sealing silicone layer 82 can further improve the sealing performance, and at the same time has deformability and adaptive fit.

[0048] It should be noted that the drive component is preferably a rack and pinion type angular stroke actuator, whose output shaft is connected to the pivot pin 83 via a spline sleeve. The air inlet and exhaust port of the pneumatic actuator are equipped with throttle valves. By adjusting the opening of the throttle valve, the opening and closing speed of the valve plate 81 can be controlled, avoiding the valve plate 81 from rapidly striking the limit step 85 and generating impact vibration, thereby preventing the impact vibration from interfering with the normal vibration screening operation of the screen plate 6. During the discharge stage, the outer valves of each layer of discharge port are opened in order from top to bottom, that is, the coarse powder intercepted by the uppermost screen plate 6 is discharged first, then the finer powders of the middle and lower screen plates 6 are discharged in sequence, and finally the finest powder is discharged from the bottom of the box 1. This sequence is consistent with the screening and grading route, avoiding cross-contamination of powders of different particle sizes during the discharge process.

[0049] In this embodiment, the valve body structure 8 installed in the feed hopper 4 is the same as that at the discharge port, but the valve plate 81 inside the feed hopper is larger than the valve plate 81 at the discharge port to accommodate the larger material throughput requirements of the feed hopper 4. Each pneumatic actuator has a three-unit air source treatment unit connected in series in the compressed air pipeline to ensure that the compressed air is dry and clean, and to prevent moisture or impurities from entering the actuator and causing the action to be stuck. The electrical control of the entire valve body structure 8 is integrated with the control system of the strong vibration component 3 and the micro vibration component 5 in the same PLC controller. The valve body action logic of each stage of feeding, screening and discharging is set by the timing program to realize fully automatic closed-loop operation.

[0050] It should be further noted that the technical solutions described in Embodiments 1, 2, and 3 are not isolated from each other. In practical applications, they can be flexibly combined according to the characteristics of the powder and the process requirements. For ordinary ultrafine powders with good flowability and that are not easily clogged, the basic classification scheme of Embodiment 1 can be used alone to reduce costs. For powders that are prone to agglomeration or have significant static electricity, it is preferable to add the micro-vibration component 5 of Embodiment 2 to Embodiment 1. For high-value or toxic and harmful ultrafine powders, the schemes of Embodiments 1, 2, and 3 should be fully combined to achieve fully enclosed and environmentally friendly production while ensuring classification accuracy and screen surface self-cleaning. The elastic elements, vibration parameters, and valve control timing involved in each embodiment should be adaptively adjusted by the control system according to the real-time working conditions to meet the screening requirements of different powders with optimal energy efficiency.

[0051] The basic principles, main features, and advantages of this application have been described above. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this application. Various changes and modifications can be made to this application without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed application.

Claims

1. A high-efficiency screening device for ultrafine powders, comprising a housing (1), characterized in that, The top front end of the box (1) is fixedly installed with a feeding hopper (4), and several support legs (2) are installed on the side of the box (1) through an elastic connecting seat (21). The box (1) is equipped with a sieving mechanism for screening ultrafine powder both inside and outside. The sieving mechanism includes multiple sieve plates (6) arranged inside the box (1) and inclined to the lower right. The sieve plates (6) are wavy and have several sieve holes (63) for discharging powder. The aperture of the sieve holes (63) of the multiple sieve plates (6) gradually decreases from top to bottom. The mass of the multiple sieve plates (6) increases layer by layer from top to bottom. The wave height and wave pitch of the wavy sieve plate (6) are positively correlated with the mass of the sieve plate (6). The left and right sides of the sieve plate (6) are fixedly connected to the side mounting plates (61). The side mounting plates (61) are connected to the inside of the box (1) through the elastic connecting seat (62). It also includes a strong vibration assembly (3) installed at the bottom of the housing (1), which is used to drive the housing (1) to vibrate; The rear end of the box (1) is provided with a discharge part (7) that is connected to each of the screen plates (6). Both the first elastic connecting seat (21) and the second elastic connecting seat (62) are composite springs, and the natural frequency of the second elastic connecting seat (62) is higher than that of the first elastic connecting seat (21). The strong vibration assembly (3) includes an exciter body (31) fixedly installed on the front side of the bottom of the housing (1). The excitation shaft of the exciter body (31) passes through the side wall of the housing (1) and is fixedly connected to the output end of the drive component (33) through a flexible coupling (32). The drive component (33) is fixedly installed on the ground through a support (331). The sieving mechanism also includes micro-vibration components (5) disposed on the left and right side walls of the housing (1), which are used to drive the sieve plate (6) to generate longitudinal vibration; The micro-vibration assembly (5) includes several vibration coils (53) that are fixedly connected at equal intervals to the outside of the side plate (61). The outside of the vibration coils (53) is fixedly connected to the transmission shaft (55) through the elastic connecting ring (54). The transmission shaft (55) passes through the side wall of the box (1) and extends to the outside of the box (1). The transmission shafts (55) on the same side of the sieve plate (6) are fixedly connected to the transmission plate (52). The transmission plate (52) is parallel to the side plate (61). The transmission plate (52) is installed on the side wall of the box (1) through several connecting brackets (57). An ultrasonic transducer (51) is also installed on the transmission plate (52). The ultrasonic transducer (51) is electrically connected to the ultrasonic generator.

2. The ultrafine powder high-efficiency screening equipment as described in claim 1, characterized in that, A resonance avoidance structure is provided between the strong vibration component (3) and the micro vibration component (5). The resonance avoidance structure includes an elastic vibration isolation sleeve (56) sleeved on the transmission shaft (55). The elastic vibration isolation sleeve (56) penetrates the side wall of the fixed box (1). The resonance avoidance structure also includes an elastic vibration isolation pad. Elastic vibration isolation pads are provided between the connecting frame (57) and the transmission plate (52) and between the connecting frame (57) and the side wall of the box (1). The elastic vibration isolation sleeve (56) and the elastic vibration isolation pad are made of rubber.

3. The ultrafine powder high-efficiency screening equipment as described in claim 2, characterized in that, The resonant avoidance structure further includes a strong vibration component (3) whose operating frequency is set to be offset from that of the micro vibration component (5); The micro-vibration components (5) corresponding to the two adjacent sieve plates (6) are 120° out of phase in the driving signal phase.

4. The ultrafine powder high-efficiency screening equipment as described in claim 1, characterized in that, The discharge component (7) includes a sliding plate (73) that is flush with the sieve plate (6) and fixedly connected to the rear side of the box body (1). The sliding plate (73) and the sieve plate (6) are fixedly connected by a flexible connecting strip (71). A sealing plate (72) is fixedly connected between the upper wall and the rear side of the lower inclined wall of the box body (1). The sealing plate (72) is set in two sets and vertically penetrates and fixes each layer of sliding plate (73). There is a space for storing powder between the two sets of sealing plates (72). Each layer of sliding plate (73) is provided with a discharge port. Each discharge port is provided with a valve body structure (8). The valve body structure (8) is divided into an inner valve and an outer valve. The two have the same structure. The feed hopper (4) is also provided with a valve body structure (8) to control the feeding process.

5. The ultrafine powder high-efficiency screening equipment as described in claim 4, characterized in that, The valve body structure (8) includes a valve plate (81), a sealing plate (72), and a feed hopper (4). The valve plate (81) is rotatably mounted in each of them via a pivot pin (83). Limiting steps (85) are provided at the contact positions between the sealing plate (72) and the valve plate (81) and between the side wall of the feed hopper (4) and the valve plate (81). A torsion spring (84) is installed on the pivot pin (83). The surface of the valve plate (81) is covered with a sealing silicone layer (82).

6. The high-efficiency screening equipment for ultrafine powder as described in claim 5, characterized in that, The pivot pin (83) is externally provided with a drive component for driving its rotation, and the drive component is a pneumatic actuator.

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