RU2478445C1 - Multifrequent screen assembly for ciecle vibrating separatos - Google Patents

Multifrequent screen assembly for ciecle vibrating separatos Download PDF

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RU2478445C1
RU2478445C1 RU2011137201/03A RU2011137201A RU2478445C1 RU 2478445 C1 RU2478445 C1 RU 2478445C1 RU 2011137201/03 A RU2011137201/03 A RU 2011137201/03A RU 2011137201 A RU2011137201 A RU 2011137201A RU 2478445 C1 RU2478445 C1 RU 2478445C1
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Russia
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sieve
frequency
assembly
sieve assembly
interface
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RU2011137201/03A
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Russian (ru)
Inventor
Иона КРУШ
Юрий Ободан
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Круш Текнолоджиз Лтд.
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Priority to RU2011137201/03A priority Critical patent/RU2478445C1/en
Priority claimed from US13/251,397 external-priority patent/US8485364B2/en
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Abstract

FIELD: process engineering.
SUBSTANCE: invention relates to vibratory separators to size solids to preset values. In compliance with one version, it comprises stretched top screen, stretched bottom screen, stiff bearing frame to connect said screens to separator vibrating housing and to allows connection thereto said top screen and said bottom screen. At least, one adapter is connected to said top screen. At least, one activator is connected to said bottom screen and arranged relative to said adapter to cause collisions there between to transmit vibration thereto. This allows to set nonlinearly the characteristics of multi-frequency transmitted excitation and self-cleaning of top screen as well as deagglomeration of sieved material when said screen assembly is excited by, at least, one vibration exciter. Note here that forced frequency of said source of single-frequency excitation approximated to one of intrinsic frequencies of said bottom screen and one activator connected to said bottom screen. In compliance with another version, screen assembly is furnished with buffer elements used as single-side uncontrolled links of top screen vibrations and inertial devices connected to top screen.
EFFECT: higher efficiency and quality.
28 cl, 16 dwg

Description

FIELD OF THE INVENTION
The present invention relates to apparatus for the separation of materials and, in particular, to separation on vibration and tamper separators of solid particles to specified sizes from a material consisting of particles of various sizes, and includes the separation of particles from bulk materials and pulps.
BACKGROUND
It is widely known that conventional methods and apparatuses for vibrational and gyroscopic separation are ineffective when applied to certain materials, such as fine powders with strong cohesion, wet and sticky bulk materials, fibrous materials, thick suspensions and generally the so-called difficult to sift materials, therefore that the meshes used for screening quickly clog, and the materials themselves have a significant tendency to agglomerate.
Numerous devices for the continuous cleaning of screen separators are also known, such as those described in US Pat. Nos. 7416085, 6422394, 5398816, 5143222, 4929346, 4122006 and others. Below are considered those of the technical solutions that are most relevant to the present invention.
For example, US Pat. No. 4,929,346 (inventor of Si-Lin) describes a self-cleaning screen assembly including a main screen flatly laid on a large support grid and a tray with plastic rings and rubber balls placed thereon so as to allow the screen to self-clean by jumping and collisions of rings and balls between the pallet and the supporting grid when they are subjected to vibrational excitation with the separator body
A similar self-cleaning screen assembly is sold by SWECO Corp. (Florence, KY, USA) under the trademark "SWECO Sandwich Screens" (see http : //www.sweco.com/product_partscreens_screens_sandwich.html , accessed 10.24.2009). This sieve assembly consists of a working grid mounted on top of the tension ring and a large supporting grid attached to the bottom of the ring, with sliders and / or balls placed between the grids. These sliders and balls bounce on the supporting mesh and hit the upper working mesh to remove stuck fibers or particles close to the size of the holes that block the mesh and reduce the screening area.
The disadvantages of these solutions are the relatively low energy transfer to the grid and the insufficient efficiency of deagglomeration and screening of "difficult" materials.
Separators based on dual frequency excitation are also known. These devices, for example, combine the use of low-frequency vibration, usually in the range of 5-30 Hz, with ultrasonic excitation in the range of 20-50 kHz, carried out by electromechanical transducers, which are powered by electronic generators that create high-frequency vibration of the grid. For example, US Pat. No. 5,398,816 (inventor of Senapati) describes a typical sieving system having an elastically supported sieve frame. The frame is excited by a low-frequency unbalanced vibration drive. High-frequency exciters of sieves with a frequency of about 20 kHz are located on the periphery of the frame. The disadvantages of this system are the relatively low energy transfer to the sieve sheet and the insufficient efficiency of deagglomeration of the material. In addition, the cost of ultrasound devices is high, as is the running cost of frequently replaced worn and torn meshes.
Another dual-frequency device is a sieve energy amplifier described in US patent US 7182206 (Hukki and others). The sieving system includes a vibrating screen separator having an elastically mounted screen frame with a low-frequency vibrator attached to it. The stretched mesh is rigidly mounted on the frame, and the vibrating transmission device is resiliently mounted on the frame and fixed relative to the stretched mesh. The vibratory transmitter includes a flat ring pressed against the stretched mesh, and vibration generators. Vibration generators are unbalanced air turbines. The frame includes support elements connecting the cylindrical sections of the housing and a concentrically mounted support ring. Compressed air is supplied to the turbines through the hollow frame elements. Turbine exhaust is controlled by valves. The low-frequency vibro drive operates in the range of 8-30 Hz, and the vibration generators of air turbines in the range from 275 to 600 Hz. The disadvantages of the device are the relatively narrow frequency range of excitation, the low transfer of mechanical energy to the sieve and, in addition, the complexity of the design and the inconvenience of operation caused by the need for another type of energy for additional vibration excitation.
A device for cleaning the mesh with percussion elements is described in US 7416085 (Kadel). This device is equipped with a screening surface with holes, and percussion elements located below the surface, which hit it from below in order to knock out particles stuck in the holes from it. These percussion elements are mounted on tensioners such as a cable or tape fixed to the bottom of the screen surface.
The main disadvantages of impact devices of this and similar types during thin screening are the rapid wear and tear of the mesh due to the local application of shock pulses, the limited cleaning zone of the mesh and the inefficiency of deagglomeration of the screened material.
Self-cleaning screening systems with high separation efficiency, achieved by generating a multi-frequency vibration with a wide frequency spectrum on a sieve, are proposed by the Authors of this application in US patent US 6845868 (see also Russian patent RU 2256515 from this family). Such a multi-frequency separator includes a housing, a single-frequency vibration source, and a mechanical converter system that converts the single-frequency vibration of the housing into a sequence of mechanical pulses applied to the interface device. These pulses cause multi-frequency vibration of the grid, which prevents clogging of the grid and provides effective deagglomeration and segregation of the material layer. In addition, the interface unit protects the grid from local shock loads, thereby extending its service life between replacements.
Multi-frequency screening systems of this type, designed as inserts in existing single-frequency separators or as stand-alone multi-frequency separators, provide highly efficient continuous separation without clogging for numerous difficult materials. However, compared to conventional separators, these multi-frequency machines have a more complex structure, require more precise assembly and adjustment methods, and have larger dimensions
SUMMARY OF THE INVENTION
The aim of the present invention is to provide an improved sieve assembly for a vibratory or tamper separator used for dimensional separation and classification of fine and ultrafine powders, as well as other difficult to sift materials, characterized by continuous self-cleaning of sieves and disintegration of agglomerates.
Another objective of the invention is to create an improved sieve assembly for a vibratory separator, which has increased productivity in comparison with existing means of dimensional separation, and improves the quality of separation of problematic materials related to difficult to sift, for example, having a tendency to jam particles close to the size of the holes of the sieve. Such an assembly uses multi-frequency mechanical excitation by continuously repeating force pulses with high accelerations transmitted to the sieve and the screening material.
Another objective of the invention is to create an effective sieve assembly for a vibratory separator using optimal forms of sieve vibrations under the influence of broadband vibration, which are stable under significant fluctuations in the flow of material to the sieve.
Another objective of the invention is to create a simple, inexpensive, reliable and durable device for modifying the most common single-frequency vibration separators into efficient multi-frequency self-cleaning machines by installing simple mechanical converter devices that are built into the sieve assembly.
Another objective of the invention is to create a multi-frequency sieve assembly with simple setup and maintenance.
Another objective of the invention is to create a compact multi-frequency sieve assembly for a typical circular vibratory separator, not requiring an increase in its dimensions.
Thus, in accordance with a preferred embodiment of the present invention, there is provided a multi-frequency self-cleaning screen assembly for use with a circular vibratory separator, which includes a vibrating housing supported on elastic supports and a single-frequency vibration excitation source of the housing. The multi-frequency sieve assembly located inside the housing includes a stretched upper sieve, a stretched lower sieve and a rigid annular frame made to attach to the separator casing, as well as to attach tensioned upper and lower sieves to it, while one or more interface devices are connected to the upper sieve is coaxially rigid annular frame, and one or more activator devices are attached to the lower sieve. The forced frequency of the source of single-frequency vibration excitation of the housing is selected near one of the natural frequencies of the lower sieve with activator devices connected to it. The latter are placed in relation to the interface devices with a given gap or in contact in order to organize continuously repeating strokes of activator devices on them, to generate excitation of the interface devices by repeated mechanical pulses and thereby provide multi-frequency excitation and self-cleaning of the upper sieve, as well as intensive loosening and deagglomeration sifted material.
Further, in accordance with an embodiment of the invention, there is provided a multi-frequency sieve assembly, further comprising an additional sieve with holes of a predetermined boundary separation class flat laid on the upper surface of the upper sieve. An additional screen is attached to the upper sieve along the contour.
Further, in accordance with yet another embodiment of the invention, there is provided a multi-frequency screen assembly further comprising an upper ring and connecting elements, so that the upper sieve is tensioned on the upper ring and the connecting elements attach the upper ring to a rigid frame.
Further, in accordance with yet another embodiment of the invention, there is provided a multi-frequency screen assembly further comprising a lower ring and connecting elements, so that the lower sieve is pulled onto the lower ring, and the connecting elements attach the lower ring to a rigid frame.
Further, in accordance with yet another embodiment of the invention, a multi-frequency screen assembly is provided in which the rigid frame further includes a mounting member for attaching the rigid frame to the separator body.
Further, in accordance with another preferred embodiment of the invention, one or more interface devices are made in the form of a ring coaxial with a rigid annular frame.
Further, in accordance with yet another preferred embodiment of the invention, the multi-frequency sieve assembly further includes an apparatus for adjusting the gap so as to allow adjustment of the air gap between the activator devices and the interface rings.
Further, in accordance with yet another preferred embodiment of the invention, the clearance adjusting apparatus is configured as one or more annular gaskets mounted between the rigid frame and the lower ring.
Further, in accordance with another preferred embodiment of the invention, the apparatus for adjusting the gap is made as one or more annular gaskets installed between the rigid frame and the upper ring.
Further, in accordance with another preferred embodiment of the invention, the activator devices further include wear-resistant protective elements attached to them from the side of the interface devices
Further, in accordance with another preferred embodiment of the invention, the interface devices further include wear-resistant protective elements attached to them by activator devices.
Further, in accordance with yet another preferred embodiment of the invention, the multi-frequency sieve assembly further includes a stretched additional sieve with holes of a predetermined separation class and a tension device that allows replacement and tension of the additional sieve, while the additional sieve is attached to the sieve assembly over the top of the sieve.
Further, in accordance with a preferred embodiment of the invention, the activator devices are made in the form of radially elongated activator elements placed symmetrically relative to the center of the rigid frame.
Further, in accordance with a preferred embodiment of the invention, at least one activator device is configured to control mass and moment of inertia.
Further, in accordance with a preferred embodiment of the invention, the multi-frequency screen assembly further includes one or more rigid carrier elements attached to the rigid annular frame, and at least one buffer element attached to the upper sieve. These buffer elements are designed as non-retaining one-way communication with a gap or in contact with respect to the rigid supporting elements of the frame.
Further, in accordance with a preferred embodiment of the invention, at least one of the buffer elements is further connected to an interface device.
Further, in accordance with a preferred embodiment of the invention, the multi-frequency sieve assembly further includes one or more inertial apparatus connected to the upper sieve.
Further, in accordance with a preferred embodiment of the invention, at least one inertial apparatus is configured to control mass and moment of inertia.
In addition, in accordance with yet another preferred embodiment of the invention, the multi-frequency screen assembly for use with a circular vibratory separator includes a top screen stretched over an annular rigid frame made to attach the screen assembly to the separator body, the frame being provided with rigid support elements rigidly attached thereto. . In addition, the sieve assembly includes one or more buffer elements attached to the upper sieve, moreover, the buffer elements are made as non-retaining one-way bonds of elastic vibrations of the sieve in the direction normal to its plane, and limiting vibrations with respect to the indicated rigid load-bearing elements. Buffer elements can be placed in relation to the rigid supporting elements of the frame with a gap or in contact. When the separator body is excited by a single-frequency exciter, a predetermined vibrational excitation of the upper sieve is generated by repeated shock pulses, its multi-frequency excitation and self-cleaning are ensured, and, as a result, the segregation and deagglomeration of the layer of sifted material is improved, and the separation performance and quality are significantly improved.
Further, in accordance with a preferred embodiment of the invention, this multi-frequency sieve assembly further includes one or more interface apparatus connected to the upper sieve for distributing multi-frequency vibration over the surface of the upper sieve.
Further, in accordance with a preferred embodiment of the invention, one or more buffer elements are further connected to one or more interface devices.
Further, in accordance with a preferred embodiment of the invention, this multi-frequency screen assembly further includes at least one inertial apparatus attached to the upper sieve.
Further, in accordance with a preferred embodiment of the invention, the inertial apparatus is configured to control mass and moment of inertia.
SUMMARY OF THE DRAWINGS
The present invention will be better understood from the following description in combination with the drawings, in which:
Figure 1 is a cross section of a circular vibratory separator showing the location in it of a self-cleaning screen assembly, according to the invention;
Figure 2 is a schematic cross section of a multi-frequency self-cleaning screen assembly attached to a separator housing according to the invention;
Figure 3 is a schematic bottom view of a multi-frequency self-cleaning screen assembly in the direction of arrow A, shown in Figure 2;
Figure 4 is a schematic cross section of a multi-frequency self-cleaning screen assembly taken along lines CC in Figure 2, a bottom view;
Figure 5 is a schematic cross-section of a multi-frequency self-cleaning screen assembly taken along lines BB in Figure 2, a top view;
6 is a schematic cross-section of yet another embodiment of a multi-frequency screen assembly according to the invention, in which the upper mesh is tensioned on the upper ring and the latter is attached to the annular frame using connecting elements;
Fig. 7 is a schematic cross-sectional view of yet another embodiment of a multi-frequency sieve assembly, in which the lower mesh is tensioned on the lower ring and the latter is attached to the annular frame using connecting elements;
Fig. 8 is a schematic cross-sectional view of yet another embodiment of a screen assembly, in which an annular gasket is used to adjust the relative position of the activator devices with respect to the interface devices;
Fig. 9 is a partial schematic cross-section of yet another embodiment of a sieve assembly according to the invention, comprising a mounting apparatus enabling simplified replacement and tensioning of an additional sieve;
Figure 10 is a schematic bottom view of another embodiment of a sieve assembly comprising rigid support elements rigidly attached to a rigid annular frame and buffer elements;
11 is a partial schematic cross section of a sieve assembly taken along lines AA in FIG. 10;
FIG. 12 is a partial schematic cross-section of a screen assembly taken along lines CC in FIG. 10;
Fig. 13 is a schematic bottom view of yet another preferred embodiment of a sieve assembly including a top sieve, buffer elements, an interface ring, and inertial apparatuses.
FIG. 14 is a partial schematic cross-section of a screen assembly taken along lines AA in FIG. 13;
FIG. 15 is a partial schematic cross-section of a screen assembly taken along lines BB in FIG. 13;
Fig is a schematic bottom view of another preferred embodiment of the invention, including lower and upper sieves, activator devices, interface devices, buffer elements and inertial devices.
DETAILED DESCRIPTION OF THE INVENTION
Turning now to FIG. 1, we will consider a conventional single-motor circular separator shown therein, designated 100 in total, with a drive in the form of a centrifugal single-frequency motor vibrator 130, using a multi-frequency self-cleaning screen assembly, indicated in general 10, constructed and operating in accordance with a preferred embodiment of the present invention . The present invention is intended primarily for screening powdered and granular materials, prone to agglomeration and blocking of the openings of the sieve surface, and which have particle sizes in the range from 0.01 to 500 microns.
The separator 100 includes a vibrated housing, designated generally 120, with a cover 123, a screen assembly 10 sandwiched in the housing 120 between the under-sieve shell 121 and the over-sieve shell 122, as well as a vibrating motor or exciter 130 mounted on the base plate 126 of the housing 120. Motor 130 It is usually a suitable single frequency motor vibrator with rotational speeds in the range of 1000-3600 rpm. Bosses 147 are attached to the housing 120, by which it rests on the support frame 150 through elastic supports 140, such as suitable springs, so as to provide suitable excitation of the separator along with suitable vibration isolation of the support structure. The inlet pipe 127 for feeding the screening material is provided in the cover 123; the first output pipe 129 for the output of the under-sieve product passing through the sieve assembly 10 is located below the sieve assembly 10 in the sub-sieve shell 121; the second outlet pipe 128, designed to unload the oversize product from the separator 100, is located in the oversize casing 122.
It is understood that the source of single-frequency vibrational excitation of the housing 120 may be an alternative dual-engine self-balancing vibrator system, which is usually used in vibro-separators with small vertical dimensions, or a gyration drive used in tamper separators, as well as other suitable drive systems.
It is also understood that in cases where a multi-deck separator is used for sieving difficult materials into three or more fractions, the corresponding number of multi-frequency sieve assemblies according to the invention can be installed inside the housing 120 in a multi-story way, while the corresponding number of second output pipes 128 for particles of different sizes classes can be provided in the corresponding number of over-sieve shells 122, and the smallest particles passing through the sieve insert with holes are minimal size, exit the housing through a single first outlet pipe. Of course, such a separator can also be driven by a single-engine or twin-engine vibrodrive or other suitable drive system.
The separator 100, despite the fact that it has a standard single-frequency excitation source, actually works as a multi-frequency due to the installation of a multi-frequency sieve assembly 10 constructed and operating in accordance with the present invention. It is understood that the separator 100 may be an existing conventional single-frequency vibratory separator, which is modified by installing in it a multi-frequency insert made according to the invention. However, it is also understood that, in accordance with an alternative embodiment of the present invention, the separator 100 can be implemented as a multi-frequency separator anew, starting from the calculation and construction stage. From the following description, the sieve assembly device 10 will be understood.
Turning now, in particular, to Figure 2, we consider a sieve assembly 10, comprising a rigid frame 11, which carries a lower sieve 18 and an upper sieve 13, stretched on a rigid frame 11 and mounted on it. The rigid frame 11 can usually be made as a ring from a pipe of rectangular cross section and have a flange mounting element 17, rigidly connected to the pipe. It is also understood that in the case where an existing standard single-frequency vibratory or tamper separator is modified by incorporating a multi-frequency screen assembly according to the invention, a suitable sized mesh ring frame typically manufactured by separator manufacturers can be used as a rigid frame 11 for manufacturing the multi-frequency screen assembly of the present invention. as a standard spare part.
The upper sieve 13 and the lower sieve 18 are usually any suitable durable metal or plastic woven mesh or perforated sieve surfaces. They are attached to the rigid frame 11 in a taut state using any suitable method, for example gluing with a suitable glue, welding, clamping with bolt and rivet joints, etc.
The rigid frame 11 is secured to the housing 120 (partially shown) by means of a mounting element 17 and an elastic gasket 125, which provide an elastic connection of the sieve assembly 10 between the sieve shell 121 and the sieve shell 122. These body parts are interconnected by a clamping ring 124, which in this way creates a tight connection sieve Assembly 10 to the housing 120 of the separator 100.
An additional thin sieve 12 is flat laid on the coarse upper sieve 13 with or without tension and is fixed on it along the general contour, for example, with suitable glue. An additional sieve 12 is the main element that determines the boundary size of the separation of particles, usually a thin sieve in the range of 600-35 mesh with a hole size of 20-500 microns; and this sieve can be easily replaced when worn or torn. In this case, the cells of the lower sieve 18 and the upper sieve 13 are selected 3-10 times larger than the openings of the additional sieve 12 in order to ensure unhindered passage through them of under-sieve particles passing through the additional sieve 12.
It should be noted that in some cases there is no need for an additional sieve, so that the upper sieve 13 can be used as the main sieve, which defines a given boundary particle size separation. In these cases, the lower sieve 18 has larger cells, which are 3-5 times larger than the cells of the upper sieve.
Referring now also to FIGS. 3-5, two pairs of radially elongated activator devices 16 are shown, which are attached to the lower sieve 18 from the side of its lower surface, symmetrically with respect to the center of the rigid frame 11. The activator devices 16 are typical impact elements made of rubber, plastic, metal or any other suitable materials, or a combination thereof. Two pairs of radially elongated protective elements 15, made of wear-resistant material, are attached to the upper surface of the lower sieve 18 in alignment with a vertical projection of the activator devices 16.
The value of one of the natural frequencies of the lower sieve 18 with activator devices 16 and protective elements 15 connected to it is selected in the vicinity of the forced vibration frequency generated by the motor-vibrator 130. This provides an intensive mode of vibration with amplification. It is understood that the activator devices 16 and the protective elements 15 can have any suitable amount, mass, dimensions, geometric shapes, location and other characteristics. The exact values of these parameters are optimized in accordance with the waveforms and characteristics of the nonlinear dynamic system.
Two interface apparatuses are made in the form of interface rings 14a and 14b and are attached to the lower surface of the upper sieve 13 coaxially with respect to the annular rigid frame 11. Their purpose is to distribute the following next pulses locally reapplied on the surface of the upper sieve 13, which generate activator devices 16. Interface the rings 14a, 14b, as well as the protective elements 15, are usually made of metal, polyurethane, rubber, nylon or any other suitable wear-resistant materials or combinations thereof, in order to prevent Red Fast wear of the contact surfaces and contamination screening products.
It is understood that anti-wear protective elements can alternatively be attached to the interface rings 14a, 14b so as to form a wear-resistant contact surface.
As follows from figure 2, in the illustrated sieve assembly, the protective elements 15 of the activator devices 16 are placed with a predetermined air gap δ (exaggerated enlarged in the diagram) relative to the interface rings 14a, 14b, in order to create elastic buffers that are necessary for proper conversion single-frequency excitation of the housing, in the multi-frequency vibration of the upper sieve. In the general case, these buffers after assembly (i.e., at rest) can be in a non-contact (i.e., with a gap) or contact (including a pressed-in state) relative position, which can significantly affect the regime of multi-frequency excitation of the sieve surface. Any of the indicated relative provisions, however, with proper selection of the system parameters and the level of vibration excitation of the case, provides alternating closure and opening of the contact surfaces of the buffers, and repeated elastic collisions between them occur. Buffers form the so-called one-way or non-holding elastic bonds, known from the nonlinear dynamics of machines. As a result, the upper sieve 13 and the lower sieve 18, stretched over the rigid frame 11, activator devices 16, protective elements 15 and interface rings 14a, 14b together form (see Figs. 1-5) a nonlinear dynamic oscillatory system capable of converting single-frequency vibration the housing 120 generated by the motor-vibrator 130, in the multi-frequency vibrations of the upper sieve 13, as well as an additional sieve 12 connected to the latter.
When starting a single-frequency motor vibrator 130 (see FIGS. 1-5), the housing 120 of the separator 100 receives three-dimensional gyrational motion, while the screen assembly 10 is excited by the vibration of the housing 120, so that the activator devices 16 connected to the lower sit 18 vibrate in a predetermined waveform of a dynamic system including a housing 120, a rigid frame 11, a lower sieve 18, activator devices 16 with protective elements 15, an upper sieve 13 and interface rings 14a, 14b. Likewise, the interface rings 14a, 14b attached to the upper sit 13 receive vibration from the housing 120 through the rigid frame 11. The parameters of this dynamic system are selected so as to provide optimal phase shifts between the vibrations of the activator devices 16 and the interface rings 14a, 14b. The predetermined phase shifts of the oscillations of these elements provide the generation of regular repetitive collisions of the activator elements 16, covered with protective elements 15, with the interface rings 14a, 14b, while the collisions occur at significant relative speeds. Since in this case a significant part of the kinetic energy of the activator devices 16 and the protective elements 15 is transmitted to the interface rings 14a, 14b and successively to the upper sieve 13, the additional sieve 12 and the screened material on the sieve, the multi-frequency system made in accordance with the present invention provides a self-cleaning action of the sieve assembly 10. At the same time, due to the vibrational dilution of the material layer occurring under the influence of multi-frequency vibration of the sieves 12, 13, deagglomeration is also provided , Loosening and intensive segregation layer of screening material is continuously supplied to the sieve.
It should be noted that the interference wave pattern at each point of the sieve surface is defined as a superposition of pulsed actions from each of the activator devices, and since these pulses are phase shifted as a result of the gyration effect on the sieve assembly, the resulting wave pattern usually corresponds to the frequency of the vibration excitation source multiplied by the number of activator devices, i.e. the mode of multiplication of the excitation frequency with the predominance of high-frequency components of the spectrum of normal accelerations.
Thus, with proper selection of the system parameters and the excitation mode in this essentially nonlinear dynamic system, when a single-frequency vibration exciter 130 is turned on, a stable limit oscillation cycle (the so-called attractor) arises and is automatically maintained. In this case, the upper sieve 13 and the thin additional sieve 12 superimposed on it receive multi-frequency excitation with a broadband Fourier spectrum close to discrete or random. Since the accelerations during oscillations are proportional to the squares of the frequencies, the high-frequency harmonics of the Fourier spectrum cause correspondingly large normal accelerations of the sieve surface, which are tens and hundreds of times higher than the maximum accelerations of the housing and generate correspondingly huge inertial forces acting on particles of material that are stuck to the sieve or stuck in its holes. These particles detach and go into the oversize product stream. In addition, many particles jump in the openings of the sieve without getting stuck in it. This also makes it possible to overcome the intermolecular and electrostatic adhesion forces and the adhesion of wet and sticky particles to the sieve. This prevents blocking of the sieve openings and a decrease in time of the open sieve surface, that is, continuous self-cleaning of the sieve is thereby achieved. Inertial forces with large amplitude values also contribute to the disintegration of particle agglomerates for those screened materials that, due to strong cohesion, are prone to agglomeration.
It is understood that the number, size and inertial parameters, as well as the bending stiffness of the interface rings 14a, 14b are optimally selected so that the transmission of shock accelerations in the form of multi-frequency vibration to all parts of the upper sieve 13 and the additional sieve 12 is sufficiently effective, i.e. to prevent clogging of the sieve openings and a decrease in the active sieve surface, while simultaneously providing vibratory liquefaction and segregation of the material layer, as well as the disintegration of agglomerates.
It is also understood that the activator devices 16 can be assembled in the form of combinations of two or more elements, one part of which is placed under the lower sieve 18, and the other part above it. In addition, provided that there is sufficient space between the lower sieve 18 and the upper sieve 13, the activator device 16 can be completely placed inside this volume, and in some cases together with anti-wear protective elements, which further reduces the size of the sieve assembly.
Among the advantages found by the authors in the above construction, we note the following:
1. Self-cleaning the sieves and preventing agglomeration of the material is carried out continuously during the operation of the separator, to enable continuous operation without the need for stops for periodic cleaning of the mesh.
2. The multi-frequency sieve assembly is a simple and inexpensive device for the modification of the universally operated single-frequency vibratory separators.
3. The screening characteristics of conventional separators in which the multi-frequency screen assembly according to the invention is installed are significantly improved by self-cleaning the screens, intensive mixing, delamination and segregation of the material layer, the specific productivity per unit area of the screen surface is significantly increased and the quality of the screening products is improved.
4. Usually, when applying the invention, due to the improved screening quality, the output of the under-sieve product increases, while the fouling of the over-sieve with a small fraction is reduced.
5. The action of the dynamic system under load is stable. The efficiency of grid self-cleaning and material deagglomeration in existing separators equipped with a multi-frequency screen assembly according to the invention is maintained even with significant fluctuations in the feed of the screened material.
6. The proposed dynamic system provides good vibration isolation of the separator housing from shock loads that are localized on the screens.
It should also be emphasized that all these advantages are ensured by using the multi-frequency converter system according to the present invention, in which the potential energy of elastic deformation is transformed into kinetic energy and vice versa in a very limited space, which does not require an increase in the overall dimensions of existing separators to be modified.
Turning now to FIG. 6, another embodiment of a multi-frequency sieve assembly is depicted, generally designated 210, and which is fundamentally similar to the sieve assembly 10 described above and shown in FIGS. 1-5, with a difference in the method of attaching the upper sieve 13. In order to simplify production and maintenance, as well as for greater technological flexibility of use, in cases of frequent changes of the screening material and the boundary separation size, the sieve assembly 210 additionally includes an upper ring 20 and connecting elements cients 21. This upper sieve 13 previously tensioned and secured to the top ring 20. Thereafter the ring 20 is attached to the frame 11 with suitable terminal elements, such as rivets, bolts, pins, clamps, etc.
Turning now to FIG. 7, we consider another embodiment of a multi-frequency sieve assembly, designated 310, which is also fundamentally similar to the sieve assembly 10 described above and shown in FIGS. 2-5, with a difference in the method of attaching the lower sieve 18. The sieve assembly further includes the lower ring 22 and the connecting elements 23. The lower sieve 18 is pre-tensioned and secured to the lower ring 22. The latter is attached to the frame 11 by the connecting elements 23.
Turning now to FIG. 8, we will consider another embodiment of the multi-frequency sieve assembly, designated 410, which is also fundamentally similar to the sieve assemblies 210 and 310 described above and shown in FIGS. 6-7, with a difference in the method of attaching the lower sieve 18. In order to To simplify the production and adjustment of the system, the sieve assembly 410 further includes an apparatus for regulating the gap between the protective elements 15 of the activator devices 16 and the interface rings 14a, 14b. The device for adjusting the gap in this design is made in the form of at least one annular gasket 24 inserted between the lower ring 22 and the rigid frame 11. The introduction of the gaskets 24 of the required total thickness makes it possible to establish an air gap of a given size between the protective elements 15 of the activator devices 16 and the interface rings 14a, 14b and thus optimize the multi-frequency spectrum of the generated vibration. It is understood that, similarly, the specified apparatus for regulating the gap can alternatively be made in the form of an adjusting gasket (not shown) inserted between the rigid frame 11 and the upper ring 20.
Turning now to FIG. 9, we will consider another embodiment of a multi-frequency sieve assembly, indicated in general 510, which is functionally similar to the sieve assembly 10 described above and shown in FIGS. 2-5, however, characterized by the placement of activator devices 16 and anti-wear protective elements 15 inside the space between the lower sieve 18 and the upper sieve 13, as well as a modification of the method of attaching an additional sieve 12, so as to ensure its tension and easy replacement during maintenance. This design is illustrated by the example of a serial sieve frame 11 with mounting device 28, which is manufactured by Cuccolini, Italy together with separators. The rigid frame 11 is formed as a ring of a Z-shaped profile 30 with a mounting flange 17 adapted for installation in a vibratory separator. The lower sieve 18 and the upper sieve 13 are tensioned and in this state are fixed to the flanges of the rigid frame 11, for example, by gluing with any suitable adhesive. The additional sieve 12 is tensioned for easy replacement using a tensioner, generally designated 28. For example, in this embodiment, the tensioner includes two annular collars 28a, 28b and two reciprocal annular grooves 29a, 29b in the annular vertical wall 30 of the frame 11, and the annular the clamps 28a, 28b are recessed into the grooves 29a, 29b by tightening the bolted joints (not shown) of the clamps. An additional sieve 12 from a suitable mesh is prepared as a piece of sieve fabric of the required size, cut from a standard roll. First, this piece is flat laid on top of the upper sieve 13 and the vertical wall 30 of the rigid frame 11. Then it is pressed to the rigid frame 11 along its contour with a collar 28a clamped in the groove 29a, after which the additional sieve 12 is finally tensioned properly by clamping the collar 28b into the groove 29b.
The authors found that the appropriate tension of the additional sieve 12 may be essential to enhance the high-frequency harmonics of the vibrational excitation frequency spectrum, which are responsible for the self-cleaning of thin sieves during sifting of difficult powder materials.
Turning now to FIGS. 10-12, we will consider another embodiment of a multi-frequency sieve assembly, designated generally 610, which is functionally similar to the sieve assembly 10 described above and shown in FIGS. 2-5, but further comprising rigid carrier elements 35, 36, rigidly attached to the rigid annular frame 11, and a set of buffer elements 42, 43, which are located opposite the rigid supporting elements 35. In addition, the activator devices 16a, 16b, indicated in General 16, are attached to the stretched lower sieve 18 and are made with the possibility of reg evidence of their mass and moment of inertia.
The rigid frame 11 is similar to the similar frame 11 shown and described in connection with FIG. 9, but with a rigid additional connection of the rigid radial elements 35 and the annular element 36. This is done, for example, by welding to provide the necessary strength and flexural rigidity of the frame 11.
Two sets of activator devices 16a, 16b are attached to the lower sit 18. Set 16a is located opposite the interface ring 14a, and set 16b is opposite the interface ring 14b. In this case, each of the activator devices 16a, 16b is configured to adjust the mass and moment of inertia. As can be seen from 11-12, in this embodiment, each activator device includes a main activator element 161 with a rigidly attached threaded element 164, one or more adjusting parts 163, a pair of mounting protective gaskets 162, a sleeve 167, a spring washer 166 and a nut 165. It is understood that the total mass and moment of inertia of each activator device can be adjusted and installed during assembly, adjustment, or service work by introducing or excluding additional adjustment elements 163 between the bottom mounting gasket 162 and nut 165 in a suitable amount, shape, and location.
The interface rings 14a, 14b have protective lining elements 151 on their surfaces facing the activator devices 16a, 16b. Wear-resistant elements 151 are attached to the interface rings 14a, 14b and the upper sieve 13, for example, by gluing with a suitable adhesive.
The buffer elements 42 are attached to the upper sit 13 and the interface ring 14a, while the buffer elements 43 are attached only to the upper sit 13 so as to form an additional set of one-sided non-retaining bonds between the upper sieve 13 and the supporting elements 35. After proper assembly, the buffer the elements at rest are in a predetermined position relative to the rigid load-bearing elements - with a gap or in contact, and in the latter case they can even be preloaded. However, during operation of the vibration separator driven by the vibration excitation source 130 (not shown), the contact surfaces of the buffer elements 42, 43 periodically open and close, while the buffer elements 42, 43 continuously generate the following mechanical pulses, generating additional multi-frequency excitation of the upper sieve 13, additional sieve 12 and material interacting with it. The buffer elements 42, 43 are usually made of polyurethane, rubber, nylon and other wear-resistant materials or combinations thereof and are attached to the upper sieve 13 and the interface rings 14a, 14b by gluing with a suitable adhesive. It should be noted that the relative position of the buffer elements with respect to the rigid load-bearing elements can significantly affect the mode of multi-frequency excitation of the sieve.
The inventors have found that the optimal combination of activator devices 16a, 16b and buffer elements 42, 43 can enhance the generation of high-frequency harmonics, increase the stability of the system with fluctuations in the mass of the load and obtain a more uniform distribution of multi-frequency vibration over the entire screen surface. This improves the separation of thin and wet materials with a high content of boundary class particles and agglomerating particles.
Turning now to FIGS. 13-15, we will consider another preferred embodiment of the multi-frequency sieve assembly, indicated in general 710, which is functionally similar to the sieve assembly 610 described above and shown in FIGS. 10-12, simplified by eliminating the lower sieve and activator devices, but further comprising a plurality of inertial apparatuses, designated 54 in general, attached to the upper case 13. Bearing elements 35, 36 are rigidly attached to the rigid frame 11. Buffer elements 42, 43 are located opposite the bearing elements 35. Buffer ele the cops 42 are attached to the stretched upper sieve 13 and the only interface ring in this assembly; buffer elements 43 are attached only to the upper sieve 13, while the combination of elements 42, 43 forms the above-described set of one-sided non-retaining bonds between the upper sieve 13 and the supporting elements 35.
As shown in FIG. 15, inertial apparatuses 54 include mass elements 55 attached to the sieve 13 via shims 56. Mass elements 55 are typically any suitable massive elements made of metal, rubber, plastic, or other suitable materials or combinations thereof. The protective pads 56 are, for example, suitable elastomeric plates capable of reducing contact stresses at the point of their attachment to the sieve 13. They are attached to the sieve 13 and to the mass elements 55, for example by gluing with a suitable adhesive. Inertial devices 54 may be configured to control inertial characteristics — mass and moment of inertia. A device for controlling the mass and moment of inertia of the inertial apparatus 54 may be performed, for example, similar to the device described above and shown in FIG. 11 in connection with an adjustable activator device 16a. The optimal placement and determination of the inertial characteristics of the set of inertial devices 54 gives a significant increase in the kinetic energy of the sieve 13, as well as an increase in the force pulses and peak accelerations generated by the buffer elements 42, 43. Moreover, for a number of options for the sieve assemblies, the simultaneous attachment of inertial devices to the upper the interface devices, and also in the immediate vicinity of the buffer elements, so in this case the interface devices are used as waveguides with minimal losses of vibrational energy.
The authors found that the sieve assembly 710 is an inexpensive simple design. The optimal placement and the right choice of parameters of inertial apparatuses 54 and buffer elements 42,43 makes it possible to enhance the generation of a high level of normal acceleration of the sieve 13, to obtain a more uniform distribution of multi-frequency vibrations on the sieve surface and thus improve the technological characteristics of the separation of fine powders, wet and sticky materials and high density suspensions in comparison with single-frequency conventional vibratory separators.
However, it should be noted that the sieve assembly 710 has weaker energy characteristics of the excitation of the upper sieve 13 than sieve assemblies with their own sieve and activator devices, and this to some extent limits the scope of the simplified assembly 710 under consideration. In addition, the designs indicated 610 (see Fig. 10-12) and 710 (see Fig. 13-15), in contrast to the designs indicated by 210, 310, 410 and 510 (see Fig. 2-9), may differ somewhat increased transmission of rocket percussion pulses generated by buffer elements 4 2, 43 to the supporting elements 35, and then to the frame 11 and the housing 120. For these reasons, if the existing single-frequency separators are modified, the sieve assembly and the separator housing must have a high-frequency spectrum of natural elastic vibrations and have adequate reserves of dynamic strength.
On Fig shows another preferred embodiment of the sieve assembly, indicated in General 810. The sieve assembly 810 includes two sets of activator devices 16A, 16b connected to the lower sieve 18 and located opposite the interface rings 14a, 14b, the latter connected to the upper sieve 13 coated with additional sieve 12; two sets of buffer elements 42,43 are attached to the upper sit 13 and are located opposite the radial elements 35, which are rigidly attached to the frame 11; a set of inertial devices 54 is also attached to the upper sieve 13. All of the devices and their elements listed here, as well as their operation, have already been described in detail above in connection with the designs of the sieve assemblies 610 and 710 shown in Figs. 10-15, and therefore we do not describe them here again.
The authors found that the execution of the sieve assembly, designated 810, is suitable for a wider range of applications than the execution 610, shown in Fig.10-13, and this is due to the increase in the energy of multi-frequency excitation transmitted to the upper sit 13, additional sit 12 and sequentially to the layer screened material. It should be noted that the additional, in comparison with version 610, attachment of inertial devices 54 to the upper sieve 13 creates an additional phase shift between the oscillations of the upper sieve 13 and the activator devices 16a, 16b. As a result of this, the relative speeds of the oncoming motion of the colliding elements increase, the excitation energy of the grids increases, the multi-frequency vibration field becomes more uniform, the separation characteristics of difficult to sifted materials improve, and the stability of operating modes with significant variations in the supply of the technological load to the separator increases.
Obviously, specialists in this field understand that the essence of the present invention is not limited to what is shown and described above, mainly by way of illustrative examples. Moreover, the essence of the present invention is limited only by the claims, which are given below.

Claims (28)

1. A multi-frequency sieve assembly intended for use with a circular vibratory separator, which includes:
- a vibrated housing made with an inlet pipe for supplying the sifted material, a first outlet pipe for unloading the sieve product and a second outlet pipe for unloading the sieve product, the at least one multi-frequency sieve assembly being placed in the housing between the inlet pipe and the first outlet pipe so that the sifted material enters the housing through the inlet pipe to the at least one sieve assembly, while the sublattice particles pass through the sieve the bar and are removed from the housing through the first outlet, while the oversize particles do not pass through the sieve assembly and are removed from the housing through the second outlet, and
- at least one source of single-frequency vibration excitation, designed to carry out the sieving of particles, and
- a support device designed to support and vibration isolation of the separator;
wherein said multi-frequency sieve assembly includes:
- stretched top sieve,
- taut lower sieve,
- a rigid annular frame made for attaching, at least indirectly, said sieve assembly to said vibrating body, and also for attaching to it, at least indirectly, said upper sieve and attaching to it at least indirectly referred to the lower sieve, while:
- at least one interface device is connected to said upper sieve,
- at least one activator device is attached to said lower sieve, and each of said at least one activator device is arranged with respect to said at least one interface device so as to provide repetitive collisions between them and vibration shock transmission excitation of said interface apparatus and thereby establish, in a nonlinear manner, the characteristics of the multi-frequency excitation transmitted between them, and to provide a given multi-frequency excitation waiting and self-cleaning of said upper sieve, as well as deagglomeration of sifted material, when said sieve assembly is subjected to single-frequency excitation from said at least one single-frequency vibration excitation source together with said vibrated body,
moreover, the forced frequency of said single-frequency vibration excitation source is close to one of the natural frequencies of said lower sieve together with said at least one activating device connected to said lower sieve.
2. The multi-frequency sieve assembly according to claim 1, further comprising an additional sieve with holes of a predetermined boundary separation class, flat laid on the upper surface of the said upper sieve and attached to it along the contour.
3. The multi-frequency sieve assembly according to claim 1, further comprising an upper ring and connecting elements such that said upper sieve is pulled onto said upper ring, and said connecting elements attach said upper ring to said rigid frame.
4. The multi-frequency sieve assembly according to claim 1, further comprising a lower ring and connecting elements such that said lower sieve is tensioned on said lower ring, and said connecting elements attach said lower ring to said rigid frame.
5. The multi-frequency screen assembly of claim 1, wherein said rigid frame further includes a mounting member for attaching said rigid frame to said housing.
6. The multi-frequency sieve assembly according to claim 1, wherein said at least one interface device is made in the form of a ring located coaxially with said annular rigid frame.
7. The multi-frequency sieve assembly according to claim 1, further comprising an apparatus for regulating the gap between said at least one activator device and said at least one interface device.
8. The multi-frequency sieve assembly according to claim 7, in which said apparatus for adjusting the gap is made as at least one annular gasket installed between said rigid frame and said lower ring.
9. The multi-frequency sieve assembly according to claim 7, in which said apparatus for regulating the gap is made as at least one annular gasket installed between said rigid frame and said upper ring.
10. The multi-frequency sieve assembly according to claim 1, wherein said at least one activator device further includes at least one security element attached to it from the side of said at least one interface device so that provide a wear-resistant contact surface.
11. The multi-frequency sieve assembly according to claim 1, wherein said at least one interface device further includes at least one security element attached thereto from said at least one activator device so that provide a wear-resistant contact surface.
12. The multi-frequency sieve assembly according to claim 1, further comprising an additional sieve with holes of a predetermined separation class and a tensioning device enabling replacement and tensioning of said additional sieve, wherein said additional sieve is attached to said sieve assembly over said upper sieve.
13. The multi-frequency sieve assembly according to claim 1, in which the said at least one activator device is made in the form of at least one radially elongated activator element placed symmetrically with respect to the center of the said rigid frame.
14. The multi-frequency sieve assembly according to claim 1, in which said at least one activator device is configured to control the mass and moment of inertia.
15. The multi-frequency sieve assembly according to claim 1, further comprising at least one rigid supporting element attached to said rigid annular frame, and at least one buffer element attached to said upper sieve, said at least at least one buffer element is designed as a non-retentive one-way connection with respect to said at least one rigid carrier element.
16. The multi-frequency sieve assembly of claim 15, wherein at least one of said buffer elements is further connected to said at least one interface apparatus.
17. The multi-frequency sieve assembly according to claim 1, further comprising at least one inertial apparatus attached to said upper sieve.
18. The multi-frequency sieve assembly of claim 17, wherein said at least one inertial apparatus is configured to control mass and moment of inertia.
19. A multi-frequency screen assembly intended for use with a circular vibratory separator, which includes:
- a vibrated housing made with an inlet pipe for supplying the sifted material, a first outlet pipe for unloading the sieve product and a second outlet pipe for unloading the sieve product, the at least one multi-frequency sieve assembly being placed in the housing between the inlet pipe and the first outlet pipe so that the sifted material enters the housing through the inlet pipe to said at least one sieve assembly, while the sublattice particles pass through said w sieve assembly and removed from the housing through said first outlet, while oversize particles do not pass through said sieve assembly and removed from the housing through said second outlet, and
- at least one source of single-frequency vibration excitation, designed to carry out the sieving of particles, and
- a support device designed to support and vibration isolation of the separator;
wherein said at least one multi-frequency sieve assembly includes:
- stretched top sieve,
- an annular rigid frame made for attaching, at least indirectly, said sieve assembly to said vibrating separator body, as well as for attaching said upper sieve to said rigid frame, wherein said rigid frame is provided with one or more rigid bearing elements, and
at least one buffer element attached to the upper sieve,
wherein said buffer element is designed as a non-retentive one-way connection of the movement of the upper sieve in a direction normal to its plane with respect to the at least one rigid supporting element, and this in order to provide a predetermined vibrational excitation by repeated shock pulses of the said upper sieves, to ensure its multi-frequency excitation and self-cleaning, and, as a result, improved segregation and deagglomeration of the layer of sifted material, when the aforementioned sieve assembly subjected to vibrational excitation from said at least one source of single-frequency vibrational excitation, together with said vibrating body.
20. The multi-frequency sieve assembly according to claim 19, further comprising at least one interface apparatus connected to said upper sieve for distributing multi-frequency vibration over the surface of the upper sieve.
21. The multi-frequency sieve assembly of claim 20, wherein said at least one buffer element is further connected to said at least one interface apparatus.
22. The multi-frequency sieve assembly according to claim 19, further comprising at least one inertial apparatus attached to said upper sieve.
23. The multi-frequency sieve assembly according to claim 20, further comprising at least one inertial apparatus connected to said upper sieve and to said at least one interface apparatus.
24. The multi-frequency sieve assembly according to claims 22 and 23, wherein said at least one inertial apparatus is configured to control the mass and moment of inertia.
25. The multi-frequency sieve assembly of claim 19, wherein said at least one buffer element is arranged relative to said at least one rigid carrier element with a gap between them at rest.
26. The multi-frequency sieve assembly according to claim 19, in which said at least one buffer element is arranged relative to said at least one rigid carrier element with contact between them at rest.
27. The multi-frequency sieve assembly according to claim 1, wherein said at least one activator device is arranged relative to said at least one interface apparatus with a gap between them at rest.
28. The multi-frequency sieve assembly according to claim 1, wherein said at least one activator device is arranged relative to said at least one interface apparatus with contact between them at rest.
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RU2746722C1 (en) * 2020-08-26 2021-04-19 Федеральное государственное унитарное предприятие "Всероссийский научно-исследовательский институт авиационных материалов" (ФГУП "ВИАМ") Screening machine control method

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