DE4418175C2 - Device and method for screening, classifying, sifting, filtering or sorting substances - Google Patents

Description

The invention relates to a device and a Ver drive for screening, classifying, sifting, filtering or Sort dry solids or solids in Liquids according to the generic terms of the independent Claims.

It is known that those generated by ultrasound swinging movements especially when sighting and Fine sieves have a favorable influence on the sieve set and exercise the screenings; the screenings are through the transmitted oscillating movements in the micronbe the agglomeration forces and Surface tensions are significantly reduced and the general tendency to clog the mesh decreases or is completely prevented.

EP 0 369 572 A2 also discloses a screening device sieve surface clamped in a frame and to this coupled piezoelectric transducer. The latter is multi-part and different between two bodies Masses clamped, of which the sieve surface nä here consists of two parts; one part is with the Screen glued, the other exchangeable. In addition, a Control loop described, the screen mesh under load should resonate - but this should be technically not possible.  

The ultrasound transducer is described in the book "Ultrasound" by Wilhelm Lehfeldt, 1973, Vogel Verlag, ISBN 3-8023-0060- 2, page 40, referred to as composite transducers and leaves in all areas of active ultrasound applications - such as ultrasonic welding and ultrasonic cleaning - insert. In this book can be found on page 48 for circuits with automatic Frequency tracking of those indicated in EP 0 369 572 A2 tated control loop mention.

All previously known methods have the disadvantage that the sound distribution over the entire active sieve mesh, in most cases from a wire mesh is very bad. The cause of this behavior is that it is usually taut in a round or Rectangular steel frame screen mesh not assembled Resonance can be excited with the working frequency. The physical requirements for this are lacking. The Screen mesh can only be considered a relatively poor ultra serving as sound conductor. If there is also screenings on the mesh, the resulting damping leads to a further reduction of the sound conductivity.

These relationships mean that after just a few Centimeters from the sound source intensity - and thus the promotional effect - strong is reduced.

Knowing these facts, the inventor has set the goal through a suitable construction to largely eliminate these disadvantages.

There should be screening and classifying processes as well as machines for it improved and the screening in the dry and wet area with the help of ultrasound.  

Resonators should be designed so that the sieve as possible over the entire area in undamped oscillating movement offset.

The teachings of unab pending claims that give subclaims further developments.

According to the invention, the ultrasonic transducer should at least a resonator adjacent to the screen surface is assigned be based on the resonance of the ultrasonic transducer coordinated and vibrated by the latter - esp especially in bending vibrations - is displaceable.

The resonator has also proven to be cheap with fingers protruding from it on the screen surface To provide resonance-transmitting elements.

In other words, the solution is that no area on the active screen surface more than approx. 20 up to 30 cm from the nearest ultrasound source lies. This is achieved with a system of resonator bars ben who work in the bending resonance mode and by one single ultrasonic transducer can be excited. Both it is commonly used round vibratory screening machines expedient to place the transducer in the center and the resonator rods radially around this transducer to arrange around. This transducer produces on be knew longitudinal vibrations in the tan gential to the longitudinal direction of vibration Resonator bars bending vibrations of the same frequency stimulate. The vibration amplitudes are around 40 kHz at about 2 µm. The required ultrasound power lies at around 60 watts per square meter of screen area.  

Because the resonator rods excited in their natural resonance the amplitude at each node of motion is un always the same depending on length and load. With the this method of using a variety of resona you have it in your hand, the sound density and the sound homogeneity on the screen fabric as desired change.

The screen mesh can be in good contact by gluing stand with each resonator rod.

According to a further feature of the invention, those Rod resonators end at a distance from the frame. The ge Entire star-shaped device is preferred over Ent coupling plates welded into the sieve frame and forms with this together a unit that is also mechanical is very stable.

The use of a variety of resonator bars that excited in bending mode by a single transducer makes it possible that there are no anechoic islands can arise on the screen mesh. So that's the up gift that the inventor has set himself on elegant Way solved. The resonator rods can have different shapes. You can bent circular or just straight. Your cross section is ge based on physical laws which chooses the excitation of the desired bend enable vibrations in a preferred direction. she can be made from solid material or from a hollow profile consist. For weight reasons, there is a hollow profile preferable.  

For example, in a further version in circular form at least one concentric ring-shaped frame The rod resonator runs through the frame with ra diale decoupling plates is connected. The ultra sound converter is attached eccentrically here.

All those decoupling plates are preferred in one Fixed the node of the movement zero point. As It turned out to be cheap on the rod resonators put on a perforated plate or a large-mesh grid.

According to the invention between ultrasonic transducers and Resonator run at least one fastening element, and the rod resonators are to be attached to this be that in bending resonance with the ultrasonic transducer swing, whereby further bending vibrations can be generated and are transferable to the screen surface.

It is within the scope of the invention that the resonator a position with an amplitude minimum or non-positively, directly or indirectly, with the Screen frame is connected; the sieve surface should pass through the Ultrasonic transducer with the resonator on at least one Be supported.

It is also within the scope of the invention that the entire sieve device by one or more superordinate Vibration systems can be moved in all levels.

Two screens can also lie one on top of the other or together of being connected, being the coarser of the two screens only for the propagation and transmission of the Vibrations is used. Can also be special Sieves are used which are made of different wire diameters exist.  

With this screening device process conditions can are produced in which between the upper and there is a pressure difference in the lower screen area and / or that the material distribution on the screen with by means of gas or liquid jet.

In a special embodiment, the screenings on the sieve by brushes and rubber profiles, Plastic and metal distributed and / or the screenings using a gas or liquid jet onto the screen surface promoted.

Bodies lying on the screen surface are also used bar that move freely to the screen surface.

According to the teaching of the invention, the distribution of the Ultrasound from the ultrasound transducer with frequency agreed formwork lines made of metal.

Ultrasound has proven to be advantageous hermetically sealed and explosion protected to design.

According to the invention, the working frequency should be in the range of 15-100 kHz.

It is important for the invention that the system is frequency and amplitude modulated, or that only frequency modulated or only amplitude modulated becomes.

Other advantages, features and details of the Erfin dung result from the following description preferred embodiments and based on the Drawing; this shows in

Fig. 1: a sectional oblique view of a sieve that can be set in oscillating motion over its entire surface with ultrasonic transducers and ra dialen bending shaft rod gates;

Fig. 2: the cross section through Figure 1 along the line II-II;

Fig. 3: the mounting area of a radial bending shaft rod resonators on a transducer neck in side view;

Fig. 4 is a plan view of another sieve with radial longitudinal waves rod resonators;

FIG. 5 shows the cross section through Figure 4 along line VV;.

FIG. 6 is a perspective view of a Ul traschallbiegeresonator with a part of a longitudinal resonator;

Fig. 7: an enlarged radial section through part of Fig. 6;

Fig. 8: the cross section through a mushroom-shaped ultra sound transducer;

Fig. 9: a cross section through an ultrasonic resonator with ra dialen rod resonators;

Fig. 10: a modified detail of Fig. 9;

Fig. 11: an oblique view of the on device according to Fig. 8;

. Fig. 12, 13: the 11 corresponding Dar positions obligations further Vorrich;

Fig. 14 is an oblique view of a wide res screen;

Fig. 15: one of Figure 3 approximately corre sponding reproduction of another transducer neck with part of a clamped perforated plate;

Fig. 16, 17: top views of parts of perforated plates;

Fig. 18 to 20: oblique views of resonator heads with perforated sheet supports;

Fig. 21, 22: fe perspective views of Resonatorköp;

Fig. 23, 24: sections through ultrasonic wall ler other versions;

Fig. 25: the longitudinal section through a screen system;

Fig. 26: an oblique view of a fine screen including a curve sketch;

Fig. 27: the top view of a Siebge webe;

Fig. 28: enlarged cross sections through screen fabric;

FIG. 29 is a plan view ren to a con verter with several Resonato;

FIG. 30: a side view of FIG. 29;

Fig. 31 to 33 show sections through different vibrating screening;

Fig. 34: the top view of an ultrasonic screening device with different bodies on a screen surface.

., An ultrasonic transducer or converter 10 according to Figures 1, 2 oscillates with a Biegewellenresonator - gitudinalresonanz in Lon - arranged axially above it and by a fixing element 12 mounted bending wave Membranresonator 14 and a plurality of bending wave bar resonators 16 a. The ultrasonic transducer 10 excites the bending wave membrane resonator 14 of diameter d to cause bending vibrations. These are transferred to the flexible shaft rod resonators 16 which project radially from it and run under a sieve surface or a sieve 18 . The sieve 18 is clamped in an annular frame 20 in FIG. 1, left, hollow or, right, full, to which the free ends 16 _{a of} the flexible shaft rod resonators 16 of a free length a end in a gap distance b.

In Fig. 2 the course of the longitudinal waves is sketched with 22 and over the screen 18 with 24 the course of the amplitude, one zero point of which is 26.

PZT rings 30 and beryllium-copper disks 32 with line connections 34 , 34 _a are alternately accommodated in a sealed base housing 28 of the ultrasound resonator 10 arranged above a transducer stand 27 . The PZT rings 30 and the beryllium-copper disks 32 are penetrated with a lower base plate 36 in the converter axis A by a grub screw, a screw 38 or the like. Organ that runs axially to the fastening element 12 . The latter passes through a converter neck 40 .

There are therefore several coordinated, coupled vibration systems that vibrate with each other at the same frequency. The diameter d of the membrane resonator 14 and the length a of the rod gates 16 are of considerable importance and must be matched to the operating frequency.

In Fig. 3, the mounting area of the radial flexible shaft rod resonators 16 of a cross section of 8 × 8 mm on the transducer neck 40 of a head width e of 80 mm is shown with an indicated vibration curve, the nodes of which recur every 21 or 42 mm.

The ultrasound transducer 10 of FIGS. 4, 5 oscillates in longitudinal resonance with an expansion wave resonator 42 fixed above it. From this radially project longitudinal rod resonators 44 , which are excited in their own longitudinal resonance. In contrast to the bending resonator in the longitudinal resonator, the amplitude zero points 26 are much further apart, as is exemplified above the sieve 18 in FIG. 5. This ultrasonic transducer 10 is optionally in one piece with its expansion wave resonator 42 .

According to FIG. 6, 7 traverses the ultrasonic transducer or con verter 10, which can be connected in the middle or at the Siebrahmenecken this Longitudinalresonator system, at a distance f, at least one radial bar 46 of Hö height h of 10 mm with a central connecting piece 47 of the height h1 of 21 mm. From this radial rod 46 , which, like the rod resonators 16, is produced from a metal profile, parallel cross rods 48 with the rectangular cross section described for the rod resonators 16 of FIG. 5 start.

A mushroom-shaped configuration of an ultrasonic transducer 10 _a , which converts longitudinal vibrations into membrane vibrations, is welded tightly to the base housing 28 in FIG. 8, which seals a tight side passage 29 for the lines 34 , 34 _{a of} two attached to PZT rings 30 Beryllium copper disks 32 - as a sandwich transducer - are offered.

This ultrasonic resonator 10 _a with the plates 30 made of piezoceramic between the contact elements 32 is in Fig. 9 to 13 with - three to eight - preferably hollow bending shaft rod resonators 16 as bending vibrators, the free ends 16 _a of wing-like decoupling plates 50 to the frame 20 are connected. Whose axially parallel connection seam 51 is in a zero motion point Be. It is a particularly well-tuned resonator for sound distribution.

A connector housing 52 with a passage 53 can be seen on the frame cross-section on the right in FIG. 9, which is fixed to a holder 54 below the frame 20 . The passage 53 of FIG. 10 runs at the height of the hollow rod resonators 16 , the interior of which is denoted by 17 and is closed by a front cover 56 .

The screen of FIG. 14 shows a screen lining of a coarser screen 18 and a fine screen 19th

In the converter neck 40 of FIG. 15, a perforated plate 58 of thickness i (preferably produced with a laser cutting machine) (of, for example, 8 mm for aluminum and of 12 mm for steel) is clamped, onto which a fine sieve 19 is glued or held in some other way , The perforated plate 58 used here offers radial ribs 59 and ring or arch ribs 60 connecting them , the spacing n of which is ϕ / 2 apart. This perforated plate 59 can also have other contours and recesses 62 . In the embodiment of FIG. 16, the ultrasonic transducer 10 17 is centrally located in FIG. At a corner.

Other perforated sheet shapes with round and rectangular recesses 62 indicate Fig. 18 above a resonator head 64 with radial rod resonators 16 and Fig. 19, 20 - the latter with honeycomb openings 62 _a - on a resonator head 65 without rod resonators.

The resonator head 66 of the ultrasonic transducer 10 _b of FIG. 21 has within the frame 20 to this in Ra dialabstand b three starting from the center Z approximately circular rod resonators 16 _k , which - straightened curved - near their free ends on thin and iw radially running decoupling plates 50 _{a are} fixed. At least one opening 49 is arranged in each of these - such an opening may also be present in the decoupling plates 50 of FIGS. 11 to 14.

The resonator head 67 of FIG. 22 carries a circular rod 68 eccentrically within the frame 20 on the decoupling plates 50 _a .

The ultrasonic screening device according to the invention can advantageously be installed as an additive in an existing vibrating screening machine 70 ( FIG. 23). With this, the ultrasonic transducer 10 is connected in a positive or non-positive manner. The inertia forces caused by the higher-level mechanical vibration system are absorbed by the ultrasonic sieve device and its attachment and are not transmitted to the sieve 18 and the sieve frame 20 . The screen 18 is thus given additional support, which is particularly important in the case of large, fine-meshed screen areas.

The ultrasonic transducer 10 of FIG. 23 is installed with its bending wave membrane resonator 14 in a round vibrating sieve machine 70 on stilts 72 . Their oscillating movements ensure a uniform distribution of the screenings 74 on the screen surface 18 and enable the discharge of the coarse material 75 through an edge exit 76th

Fig. 24 shows that a plurality of bending wave resonators 14 one above the other in a frequency adapted from stood q of ϕ / 2 can be excited by an ultrasonic transducer 10 .

In Fig. 25 are two wires 18, 19 to each other, wherein the one wire 18 is used only for reproduction and transmission of the vibrations. The vibration is transferred by means of adhesive or by the weight of the sieve. The invention has the advantage that not only steel screens that transmit ultrasound well are used, but also synthetic screen and filter fabrics as fine screens 19 . Large areas can also be sonicated.

The fine sieve 19 is fixed only at the edge (fixing points 76 in FIG. 26), and it is pressed through the sieve material onto the support grid 18 , the ultrasound being transmitted only when the sieve material 19 is loaded on the fine sieve. The support grid 18 be here, for example, from steel wires of 2 to 4 mm in diameter. The frame parts are separated by a gap at 78. A vibration pattern is indicated below the sieve surface.

In a special sieve fabric for ultrasound sie ben is according to Fig. 27, 28 of the wire mesh 18 _b under different thickness; thanks to the thicker wires, the ultrasound spreads all over the sieve 18 .

Referring to FIG. 29, 30 ultrasound is transmitted with coordinated scarf conductors 80 made of metal of a converter 10 in connecting with a sieve resonators 14, 16. The ultrasonic transducer 10 is therefore not directly connected to the resonator 14 , 16 here either.

In the following figures of the drawing, aids are shown which support sieving with ultrasound. So is FIG. 31 is a vibratory screening apparatus 70 with ultrasound again, generating a pressure difference between the upper and lower sieve surface in the vessel in a 82nd

In Fig. 32, the screenings are shot through the nozzle 84 by air jet 86 on the screen surface 18 at an ultrasonic-sieve apparatus, which affects the throughput of the seven positive.

FIG. 33 shows an ultrasonic sieve device in which gas or liquid jets 86 , brushes 88 and / or profiles 89 made of rubber, plastic and metal are used for the material distribution on the sieve 18 .

Finally, ball elements 90 made of metal or plastic are provided on the sieve 18 of FIG. 34, which move by ultrasound and press the material to be sieved through the mesh.

Claims (28)

1. Device for sieving, classifying, classifying, filtering or sorting dry solid substances or solid substances in liquids with a sieve surface provided in a sieve frame and this assigned ultrasonic transducer, through which the sieve surface vibrations can be fed, characterized in that the ultrasonic transducer ( 10 ) at least one of the screen surface ( 18 ) adjacent resonator ( 14 ) is assigned, which is tuned to the resonance of the ultrasonic transducer and by the latter in vibrations, in particular in bending vibrations, can be set ver. 2. Device according to claim 1, characterized in that the resonator ( 14 ) with finger-like from it on the screen surface ( 18 ) projecting resonance-transmitting elements ( 16 ) is provided. 3. Apparatus according to claim 1 or 2, characterized in that the resonator ( 14 ) is provided in the center of the screen surface ( 18 ) and the resonance transmitting elements as rod resonators ( 16 ) project radially from it. 4. Device according to one of claims 1 to 3, characterized in that the rod resonators ( 16 ) at a distance (b) to the frame ( 20 ) end. 5. Apparatus according to claim 3 or 4, characterized in that the free ends ( 16 _a ) of the rod resonators ( 16 ) by thin decoupling plates ( 50 ) with the frame ( 20 ) are connected, the decoupling plates preferably in a node of Zero point of movement are fixed. 6. The device according to claim 4, characterized in that curved rod resonators ( 16 _k ) from the Zen center (Z) and at a distance from the frame ( 20 ) on this by radial plates ( 50 _a ) are connected, the radial plates preferably in one Node of the zero point of motion are defined. 7. The device according to claim 1 or 2, characterized in that a circular frame ( 20 ) extends at least one concentric annular rod resonator ( 68 ) and is connected to the frame by radial plates ( 50 _a ), the radial plates preferably be in a node of the zero point of motion are defined. 8. The device according to claim 7, characterized in that the ultrasonic transducer ( 10 ) is mounted eccentrically. 9. Device according to one of claims 3 to 6, characterized in that at least one perforated plate ( 58 ) rests on the rod resonators ( 16 , 16 _k ). 10. Device according to one of claims 9, characterized in that the perforated plate ( 58 ) replaces the rod resonators. 11. The device according to any one of claims 3 to 9, characterized in that between the ultrasonic transducer ( 10 ) and resonator ( 14 ) at least one loading fastening element ( 12 ) extends and on this the rod resonators ( 16 ) are clamped, the longitudinal resonance in Lon vibrate with the ultrasonic transducer, further bending or longitudinal vibrations being able to be generated and transmitted to the screen surface ( 18 ). 12. Device according to one of claims 1 to 11, characterized in that the resonator ( 14 , 16 ) is positively or non-positively, directly or indirectly, connected to the screen frame ( 20 ) at a point having an amplitude minimum. 13. The device according to one of claims 1 to 12, characterized in that the screen surface ( 18 ) by the ultrasonic transducer ( 10 ) with the resonator gate ( 14 ) is supported at at least one point. 14. Device according to one of claims 1 to 13, there characterized by being characterized by at least one higher-level vibration system in all levels is designed to be movable. 15. The device according to one of claims 1 to 14, characterized in that a base housing ( 28 ) of the ultrasonic transducer ( 10 ) seals it associated piezo-ceramic parts ( 30 ) and contact elements ( 32 ) airtight. 16. The device according to one of claims 1 to 15, characterized by two superimposed sieve surfaces ( 18 , 19 ) of different mesh sizes, the coarser of the two sieve surfaces ( 18 ) being used for the propagation and transmission of the vibrations. 17. The apparatus according to claim 16, characterized in that the screen surfaces ( 18 , 19 ) are connected to each other ver. 18. The device according to at least one of claims 1 to 17, characterized by a sieve from ver different wire diameters. 19. The device according to at least one of claims 1 to 18, characterized by a pressure difference between the upper and lower screen surface ( 19 , 18 ). 20. The device according to at least one of claims 1 to 19, characterized by a gas or liquid jet ( 86 ) on the screen surface ( 18 , 19 ) for material distribution or conveyance of screenings ( 72 ). 21. The device according to at least one of claims 1 to 20, characterized by on the screen surface ( 18 , 19 ) distributed brushes ( 88 ) and / or profiles ( 89 ) made of rubber, plastic or metal for Ma material distribution. 22. The device according to at least one of claims 1 to 21, characterized by bodies ( 90 ) on the screen surface ( 18 , 19 ) which are freely movable to this. 23. The device according to at least one of claims 1 to 22, characterized by switching lines made of metal for frequency-tuned distribution of the ultrasound from the ultrasound transducer ( 10 ). 24. Methods for screening, classifying, sifting, filtering or sorting dry solid or solid Substances in liquids with in a sieve frame provided screen area and this assigned Ultrasonic transducer through which the screen surface Vibrations are supplied, especially with a screening device according to at least one of the previous claims, characterized records that from one outside of a screen area fixed ultrasound transducer ultrasound over at least one connected to the screen surface Resonator of the screen surface and radially to the Resonator is passed along this. 25. The method according to claim 24, characterized by a working frequency in the range of 15-100 kHz. 26. The method according to claim 25, characterized by Frequency modulation. 27. The method according to claim 5, characterized by Amplitude modulation. 28. The method according to claim 25, characterized through frequency and amplitude modulation.