Screening device and method for long and thin strip-shaped particles

Abstract

The screening device comprises a box body and a rack and further comprises an upper-layer screen mesh assembly and a lower-layer screen mesh assembly, the upper-layer screen mesh assembly adopts a screen mesh with rectangular holes, and the long edges of the rectangular holes are arranged in the direction of a synthetic excitation vector; the lower-layer screen assembly adopts a round hole or square hole sieve; the vibration excitation mechanism is installed on the rack and used for providing synthetic vibration excitation vectors dominant in the length direction of the rectangular holes for the upper-layer screen cloth assembly; the relative horizontal inclination angle alpha of the upper-layer screen assembly and the lower-layer screen assembly is 0-15 degrees; and the included angle theta between the direction of the synthetic excitation vector and the upper-layer screen assembly is 0-15 degrees. By adjusting the included angle of the upper-layer screen mesh assembly relative to the direction of the synthetic excitation vector and the inclination angles of the upper-layer screen mesh assembly and the lower-layer screen mesh assembly, optimization between the passing rate and the hole blocking rate is achieved, the instantaneous hole blocking rate of the upper-layer screen mesh is lower than 2%, the stable operation hole blocking rate is lower than 0.5%, and the energy consumption and the maintenance cost are reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bulk material screening and classification, and particularly relates to a screening device and method for elongated strip-shaped particles. BACKGROUND

[0002] The existing industrial screening equipment generally adopts round-hole or square-hole screen meshes, which have good passing characteristics for particles close to spheres or equiaxed particles. However, for elongated strip-shaped particles (elongated cylinders, short strip-shaped extrudates), since the particles have a clear length direction, when the particles are transversely oriented or cross the hole at an inclined angle, “bridging” and “impaction” are easily formed, resulting in: (1) The holes on the upper screen surface are blocked, and frequent shutdown and cleaning are required.

[0003] (2) The effective opening rate decreases, and the processing capacity and classification accuracy decrease.

[0004] (3) The mixing of powder and strip-shaped particles increases, affecting subsequent packaging and quality stability.

[0005] To solve the above problems, common improvements in the industry include increasing the hole diameter, increasing the amplitude, or adding a mesh cleaning device. However, simply increasing the hole diameter will increase the risk of mixing in large particles; increasing the amplitude and cleaning the mesh can alleviate the problem, but the energy consumption and maintenance cost increase, and it is still difficult to completely solve the hole blocking problem for high-yield lines. SUMMARY

[0006] In view of the deficiencies in the prior art, the purpose of the present application is to provide a screening device and method for elongated strip-shaped particles, which solves the problems of large particle mixing risk, high energy consumption and maintenance cost in the prior art devices and methods.

[0007] To solve the above technical problems, the present application adopts the following technical solutions: a screening device for elongated strip-shaped particles, comprising a box body and a rack installed in the box body, further comprising an upper screen assembly and a lower screen assembly installed on the rack.

[0008] The upper screen assembly adopts a screen mesh with rectangular holes, and the lower screen assembly adopts a round-hole or square-hole screen.

[0009] Further comprising a vibration excitation mechanism installed on the rack, the vibration excitation mechanism is used to provide a combined excitation vector along the long direction of the rectangular hole to the upper screen assembly.

[0010] The relative horizontal inclination angle α of the upper screen assembly and the lower screen assembly is 0°-15°.

[0011] The included angle θ between the direction of the combined excitation vector and the upper screen assembly is 0°-15°, and the direction of the combined excitation vector is determined by the combined excitation vector.

[0012] The application also has the following technical features: The box is also provided with a feeding port, and a buffer and rectifier plate is arranged at the feeding port to ensure that the material enters the upper layer screen assembly in a thin layer to avoid false plugging caused by a thick layer.

[0013] The box is also provided with a feeding port, and a buffer and rectifier plate is arranged at the feeding port to ensure that the material enters the upper layer screen assembly in a thin layer to avoid false plugging caused by a thick layer.

[0014] The material enters the lower layer screen assembly through the rectangular hole, and the material on the lower layer screen assembly and the powder below the lower layer screen assembly are discharged through the corresponding discharge system.

[0015] The length-width ratio L / W of the length L of the rectangular hole to the width W of the rectangular hole is 2:1 to 12:1.

[0016] The length L of the rectangular hole is greater than the diameter D of the target particle and less than the length H of the target particle.

[0017] The ratio of the thickness of the upper layer screen assembly to the width W of the rectangular hole is 0.1 to 0.4 to balance the strength and the passing rate.

[0018] The upper layer screen assembly is made of wear-resistant materials, including stainless steel, manganese steel, polyurethane or composite screen plate, and the hole edge of the rectangular hole is provided with a chamfer or a round corner transition to reduce the carding.

[0019] The excitation mechanism adopts a combination of an eccentric motor and a linear vibrator.

[0020] The excitation mechanism provides a vibration acceleration Γ of 1.5g to 5g and a frequency of 10 Hz to 60 Hz.

[0021] The relative horizontal inclination angle α of the upper layer screen assembly and the lower layer screen assembly is preferably 4°-12° The angle θ between the synthetic excitation vector direction and the upper layer screen assembly is preferably 0°-10° The length-width ratio L / W of the length L of the rectangular hole to the width W of the rectangular hole is preferably 3:1 to 8:1.

[0022] The length L of the rectangular hole, the diameter D of the target particle and the length H of the target particle satisfy D

[0023] The application also provides a screening method for elongated strip-shaped particles, which is implemented by using the above device and includes the following steps: Step one: The material in the form of elongated strip-shaped particles formed by granulation or extrusion molding is fed to the upper layer screen assembly provided with a rectangular hole through the feeding port.

[0024] Step 2: The excitation mechanism provides a dominant synthetic excitation vector along the length of the rectangular holes to the upper screen assembly, so that the slender strip particles form a dominant motion component along the length of the rectangular holes in the upper screen assembly, allowing the slender strip particles to pass through the upper screen assembly smoothly regardless of whether they are horizontally or vertically oriented.

[0025] Step 3: The slender strip-shaped particles that have passed through the upper screen assembly are introduced into the lower screen assembly for further screening of the powder-grade fines to obtain the target particle size product and the powder recovery stream.

[0026] Compared with the prior art, the present invention has the following technical effects: (I) The present invention provides a screening device and method for slender strip-shaped particles. By adjusting the angle between the upper screen assembly and the direction of the synthetic excitation vector, as well as the inclination angle between the upper screen assembly and the lower screen assembly, the throughput and clogging rate are optimized, so that the instantaneous clogging rate of the upper screen is less than 2%, the stable operation clogging rate is less than 0.5%, and the energy consumption and maintenance costs are reduced.

[0027] (II) The present invention provides a screening method for slender strip-shaped particles, particularly applicable to slender strip-shaped particles such as feed, fish bait, clean cat litter, explosive particles, plastic masterbatch segments, etc., which can reduce screen clogging and improve continuous production capacity and screening accuracy.

[0028] (III) The present invention provides a screening device for slender strip-shaped particles, which has a simple structure, is easy to operate, is safe and reliable, and has strong adaptability. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the overall structure of the sieving device for slender strip-shaped particles according to the present invention.

[0030] Figure 2 This is a schematic diagram of the rectangular holes in the upper screen assembly of the present invention.

[0031] Figure 3 A bar chart showing the comparative experimental results.

[0032] The meanings of the labels in the attached diagram are as follows: 1-Box body, 2-Frame, 3-Upper screen assembly, 4-Lower screen assembly, 5-Vibration mechanism, 6-Feed inlet.

[0033] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0034] Unless otherwise specified, all components in this invention are components known in the prior art.

[0035] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0036] Example 1: This embodiment provides a screening device for slender, elongated particles, such as... Figure 1 As shown, the device includes a housing 1 and a frame 2 installed inside the housing 1. It also includes an upper screen assembly 3 and a lower screen assembly 4 installed on the frame 2. The upper screen assembly 3 uses a screen with rectangular holes, such as... Figure 2 As shown.

[0037] The lower screen assembly 4 is a round or square hole screen.

[0038] The upper screen is used to allow slender, elongated particles to pass through preferentially to reduce the probability of clogging, while the lower screen is used to further remove powder from the material passing through the upper screen.

[0039] The rectangular holes in the upper screen assembly 3 are arranged along the direction of the synthetic excitation vector to accommodate the geometric anisotropy of slender, strip-shaped particles. When a particle lies horizontally across the hole, it rolls or slides under the influence of vibration and gravity, changing to a partially longitudinal orientation, allowing one end to enter the hole first and then the entire particle to pass through, significantly reducing the probability of bridging. This achieves a high pass-through probability regardless of whether the particle is horizontal or vertical. The lower screen assembly 4 maintains traditional round or square holes for powder-level separation. Through the synergistic design of hole shape and kinematics, upper-layer clogging is significantly reduced, increasing throughput per unit area and stable production capacity.

[0040] It also includes an excitation mechanism 5 mounted on the frame 2, which is used to provide the upper screen assembly 3 with a composite excitation vector that is dominant along the length of the rectangular holes; such as Figure 1 As shown, direction A is the feeding direction, direction B is the discharging direction, direction C is the powder discharge direction after sieving, direction E is the direction of the combined excitation vector, direction F is the component of the combined excitation vector perpendicular to the upper screen assembly 3, direction G is the component of the combined excitation vector parallel to the upper screen assembly 3, and direction D is the horizontal direction.

[0041] The vertical component is used to loosen the material layer and promote particle rotation. When using dual vibrating motors, the two motors are installed symmetrically and self-synchronized in opposite directions; the angle β between the motor axis and the normal to the screen surface can be 30°–45°, so as to form a significant pushing component in the screen surface plane.

[0042] like Figure 1 As shown, the relative horizontal inclination angle α between the upper screen assembly 3 and the lower screen assembly 4 is 0°-15°.

[0043] like Figure 1 As shown, the angle θ between the long side direction G of the rectangular holes on the upper screen assembly 3 and the direction E of the synthetic excitation vector is 0°-15°. This induces material particles to pass through orientably and suppresses lateral bridging.

[0044] The advantage of this embodiment is that: (1) Significantly reduces bridging and clogging: Rectangular holes provide an "escape channel" along the length direction, and particles are prone to rotation and tumbling under vibration, resulting in a high throughput.

[0045] (2) Increased capacity and opening rate: Under the same screen area, the throughput and finished product yield are increased.

[0046] (3) Precision and stability: The upper limit of powder particle size is precisely controlled by the lower layer of round / square holes to ensure the consistency of product particle size.

[0047] (4) Compatibility: The upper screen plate can be modified based on existing vibrating screens, linear screens, rotary screens or drum screens, and the cost is controllable.

[0048] The materials for the upper screen assembly 3 and the lower screen assembly 4 can be selected as follows: stainless steel 304 / 316 (food and feed friendly, explosive particles need to be grounded), high manganese steel (impact resistant), polyurethane screen plate (wear resistant and noise reduction), and composite metal-elastomer.

[0049] The rectangular holes on the upper screen assembly 3 are chamfered with R or C, with R being 0.2–0.6 mm, to reduce jamming and wear.

[0050] Modular assembly dimensions facilitate replacement and maintenance.

[0051] It can be equipped with a rubber ball, ultrasonic or air sweeping device, but high-frequency cleaning is usually not required under the hole shape of the present invention.

[0052] Regularly check the opening rate and wear, and fine-tune the vibration parameters based on the blockage rate, throughput and energy consumption.

[0053] Adjust the tilt angle and amplitude according to the moisture and oil content of the material to prevent the screen from clogging.

[0054] This application may also adopt the following alternatives: (1) Staggered arrangement of holes: The adjacent rectangular holes are arranged in a staggered manner in the longitudinal and transverse directions to weaken the bridging between holes.

[0055] (2) Micro-tilted holes: The rectangular holes are set with a micro-taper of 1°–5° relative to the normal direction of the sieve plate to improve the anti-jamming performance (the size of the top hole is larger than the bottom hole or vice versa, depending on the requirements).

[0056] (3) Multi-segment gradient: The upper layer adopts a double-segment rectangular hole. The first segment W≈D and the second segment W is slightly larger than D, taking into account both passage and selection.

[0057] (4) Surface treatment: Teflon coating or sandblasting to reduce the coefficient of friction, suitable for high-oil feed.

[0058] (5) Compatible equipment: It can be used for linear vibrating screens, swing screens, and drum screens (rectangular holes are arranged circumferentially in the drum screen, and the rolling direction is consistent with the length of the holes).

[0059] As a preferred embodiment: The housing 1 is also provided with a feed inlet 6, and a buffer and rectifier plate is installed at the feed inlet 6 to ensure that the material enters the upper screen surface in a thin layer, avoiding false blockage caused by a sudden thick layer. The housing 1 is also equipped with a discharge system, which is mounted on the frame 2.

[0060] As a preferred embodiment: The rectangular hole satisfies a length-to-width ratio L / W of 2:1 to 12:1.

[0061] The length L of the rectangular hole is greater than the diameter D of the target particle and less than the length H of the target particle.

[0062] The ratio of the thickness of the upper screen assembly 3 to the width W of the rectangular hole is 0.1 to 0.4.

[0063] The upper screen assembly 3 is made of wear-resistant material, and the edges of the rectangular holes are chamfered or rounded.

[0064] As a preferred embodiment: The excitation mechanism 5 is a combination of an eccentric motor and a linear vibrator.

[0065] The vibration acceleration Γ provided by the excitation mechanism 5 is 1.5g to 5g, and the frequency is 10Hz to 60Hz.

[0066] As a preferred embodiment: The relative horizontal inclination angle α between the upper screen assembly 3 and the lower screen assembly 4 is preferably 4°-12°. The angle θ between the direction of the synthesized excitation vector and the upper screen assembly 3 is preferably 0°-10°.

[0067] As a preferred embodiment: The rectangular hole is preferably 3:1 to 8:1 in length-to-width ratio L / W.

[0068] For the rectangular hole, the hole length L, the diameter D of the target particles, and the length H of the target particles satisfy D < L < 0.9H.

[0069] Example 2: A screening method for slender strip-shaped particulate matter, realized by using the device described in Example 1, includes the following steps: Step 1: Supply the material in the form of slender strip-shaped particles obtained by granulation or extrusion molding to the upper screen assembly 3 provided with rectangular holes through the feed port (6).

[0070] Step 2: Provide a synthetic excitation vector that is dominant in the direction of the rectangular hole length to the upper screen assembly 3 through the excitation mechanism 5, so that the slender strip-shaped particles form a dominant motion component in the length direction of the rectangular hole on the upper screen assembly 3, enabling the slender strip-shaped particles to pass through the upper screen assembly 3 smoothly regardless of whether they are lying horizontally or vertically.

[0071] Step 3: Introduce the slender strip-shaped particles passing through the upper screen assembly 3 into the lower screen assembly 4 to further screen out the fine powder materials, and obtain the target particle size product and the powder recovery material flow.

[0072] Assume that the strip-shaped particles are approximately cylindrical, with a diameter D and a length H.

[0073] (1) The upper hole length L and the hole width W: D < L < 0.9H, to avoid the entire root being stuck horizontally and to limit the passing of overly long foreign objects through screening, W takes a value from 0.9D to 1.2D, preferably about 1.0D, to balance the passing performance and the interception of large particles on the screen.

[0074] It is recommended that L / W be 3:1 to 8:1.

[0075] (2) The plate thickness t: t / W is 0.1 to 0.4, considering stiffness and wear resistance.

[0076] (3) The screen surface inclination angle α: 0° to 15°; when the material has a high water content or viscosity, α takes the upper limit.

[0077] (4) Vibration parameters: The frequency f = 15 - 50 Hz, the peak acceleration Γ = 1.5 - 5g, and the component along the hole length direction ≥ 60% of the total vibration, to promote particle orientation and self-rotation.

[0078] (5) The lower layer hole diameter P: Set according to the upper limit particle size of the powder to be removed. If the powder is defined as particles smaller than 0.5D, the equivalent hole diameter P ≈ 0.4D - 0.6D can be taken, and calibrated by on-site trial screening.

[0079] Typical parameter examples: a) Particles: Mixed explosive particles with a diameter D = 2.0 mm and a length H = 5 - 8 mm.

[0080] b) Upper layer: W=2.1mm, L=7mm (L / W≈3.3), sieve inclination angle 8°, f=25Hz, Γ≈2.2g.

[0081] c) Lower layer: The equivalent pore diameter of the round holes is P=1.5mm, which is used to remove fine powder.

[0082] d) Results: The throughput of the experimental line increased by about 50-70%, the steady-state pore blockage rate in the upper layer was <0.5%, and the powder content of the product decreased by 30-50%.

[0083] Specific effects are as follows Figure 3 As shown.

[0084] The above technical solutions are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions conceived by those skilled in the art within the scope of the technology disclosed in the present invention without creative effort are covered within the scope of protection of the present invention.

Claims

1. A screening device for elongated, strip-shaped particles, comprising a housing (1) and a frame (2) installed within the housing (1), further comprising an upper screen assembly (3) and a lower screen assembly (4) installed on the frame (2), characterized in that, The upper screen assembly (3) uses a screen with rectangular holes, and the lower screen assembly (4) uses a screen with round or square holes. It also includes an excitation mechanism (5) mounted on the frame (2), the excitation mechanism (5) being used to provide the upper screen assembly (3) with a composite excitation vector that is dominant along the length of the rectangular hole; The relative horizontal inclination angle α between the upper screen assembly (3) and the lower screen assembly (4) is 0°-15°; The angle θ between the direction of the synthetic excitation vector and the upper screen assembly (3) is 0°-15°.

2. The screening device for elongated, strip-shaped particles as described in claim 1, characterized in that, The box (1) is also provided with a feed inlet (6), and a buffer and rectifier plate is provided at the feed inlet (6). The box (1) is also equipped with a discharge system, which is installed on the frame (2).

3. The screening device for elongated, strip-shaped particles as described in claim 2, characterized in that, The rectangular hole satisfies a length-to-width ratio L / W of 2:1 to 12:

1. The length L of the rectangular hole is greater than the diameter D of the target particle and less than the length H of the target particle; The thickness of the upper screen assembly (3) is 0.1 to 0.4 of the width W of the rectangular hole. The upper screen assembly (3) is made of wear-resistant material and the edges of the rectangular hole are chamfered or rounded.

4. The screening device for elongated, strip-shaped particles as described in claim 2, characterized in that, The excitation mechanism (5) adopts a combination of an eccentric motor and a linear vibrator. The vibration acceleration Γ provided by the excitation mechanism (5) is 1.5g to 5g and the frequency is 10 Hz to 60 Hz.

5. The screening device for elongated, strip-shaped particles as described in claim 2, characterized in that, The relative horizontal inclination angle α between the upper screen assembly (3) and the lower screen assembly (4) is preferably 4°-12°; The angle θ between the direction of the synthetic excitation vector and the upper screen assembly (3) is preferably 0°-10°.

6. The screening device for elongated, strip-shaped particles as described in claim 2, characterized in that, The rectangular hole preferably has a length-to-width ratio L / W of 3:1 to 8:

1. The length L of the rectangular hole, the diameter D of the target particle, and the length H of the target particle satisfy the following relationship: D <L<0.9H。 7. A method for sieving elongated, strip-shaped particles, characterized in that, Implemented using the apparatus described in any one of claims 1-6, comprising the following steps: Step 1: The material, which has been granulated or extruded into long and thin strips, is fed through the feed inlet (6) to the upper screen assembly (3) with rectangular holes. Step 2: The excitation mechanism (5) provides the upper screen assembly (3) with a dominant composite excitation vector along the length of the rectangular hole, so that the slender strip particles form a dominant motion component along the length of the rectangular hole in the upper screen assembly (3), so that the slender strip particles can pass through the upper screen assembly (3) smoothly regardless of whether they are horizontal or vertical. Step 3: The slender strip-shaped particles passing through the upper screen assembly (3) are introduced into the lower screen assembly (4) to further screen out the fine powder material and obtain the target particle size product and powder recovery material stream.

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