EP0681514B1 - Screen, accessory for screen and screening process - Google Patents

Abstract

The screening efficiency may be increased in an improved screen by equipping the screen with a compulsory mixer (5). The materials to be screened, which are moved forward in a main flow direction (1) towards a discharge end (11), are thus thoroughly mixed during the screening process, so that the desired increase in screening efficiency is achieved.

Description

The invention relates to a screening device, an additional device for a screening device, and a screening method.

The effectiveness of screening devices depends on the movement of the fine grain content in the screenings. The ideal solution would be to guide the screenings, in which every undersize is given the opportunity to hit a screen opening and fall through.

For this reason alone, vibrating sieves are used, for example linear vibrating sieves. By using such vibrating or vibrating screens, the classification of the material to be screened, i.e. the screening process itself can be made more effective and efficient.

From the generic GB-A-1 462 038 a haze extraction device has become known which comprises a sieve device which is arranged in a closed housing. The dust-vapor mixture is fed to this so-called extraction chamber via an inlet flap and moistened by means of a spraying device. Paddles are rotated via an axis arranged transversely to the feed direction in order to support the flow of the material to be screened.

DE-B-12 66 115 describes a device for sieving material containing balls and balls. Here too, the screenings are arranged at an incline via a funnel Sieve fed. Above the sieve surface there is a stationary device for loosening the balls and balls, which comprises a substantially vertically oriented axis which can be driven by a motor and on which a plurality of projecting rods distributed in the circumferential direction protrude. The axis of rotation of the bars is arranged perpendicular or inclined to the screen covering. In other words, the circular movement of the bars can take place in a circular plane parallel or inclined to the screen covering. These rotating rods are used to loosen the mixed scrap appropriately in order to improve and support the sieving process.

A screening device is known from DATABASE WPI Section Ch, Week 7642, which comprises two screw extruders that run to an intermediate, vertically arranged axis of rotation. The screw extruders rotate around the vertical axis and move the screenings forward in the radial direction. It is a pure conveying and feeding device for the screened material towards the screen edge.

Reinigungseffekt" soll eine Verstopfung der Sieblöcher entgegengewirkt werden. Bei der Fortbewegung dieser V-förmigen Siebbleche wird das Siebgut auf der einen rampenförmigen Seite angehoben und auf der anderen rampenförmigen Seite des Bleches wieder in Richtung Siebfläche abgelegt.A cleaning device for a sieve has become known from GB-A-1 069 063. It comprises reversed V-shaped sheets which rest with their opening side on the top of a perforated sheet-like screen and can be adjusted by means of chains across the screen, which are laid on the underside of the V-shaped sheets. Through this

Clogging of the sieve holes is to be counteracted. When these V-shaped sieve plates move, the material to be sieved is raised on one ramp-shaped side and placed on the other ramp-shaped side of the plate again in the direction of the sieve surface.

In contrast, it is an object of the present invention to provide an improved screening device and an additional device for increasing the screening efficiency as well as an improved one To create screening processes, which should improve the efficiency and effectiveness during screening.

The object is achieved with respect to the screening device in accordance with the features specified in claim 1, with regard to the additional device suitable for a screening device in accordance with the features in claim 14 and with regard to the screening method in accordance with the features specified in claim 15. Advantageous embodiments of the invention are specified in the subclaims.

By means of the present invention, compared to conventional sieves, a possibility is created to actually significantly improve the mixing of the material during the sieving process, which - as has been shown - is actually the essential prerequisite for the sieve efficiency to be significantly increased again compared to conventional solutions.

As is known, the grain layer often dances on the vibrating sieve, in particular, without any significant mixing taking place. In the case of soft and plastic material, the upward and downward movement of a vibrating sieve can even cause the material to compact, which greatly impairs the mixing. Gut moisture can also lead to a deterioration in the screening efficiency. Despite sieving aids such as elastic balls hitting the underside of the sieve cannot effectively improve the sieving efficiency. In the last-mentioned example, in particular, the opposite effect occurs, since it can even lead to a blockage of the sieve opening.

The imperfect separation of the undersize ultimately results in an economic loss.

This can be effectively counteracted with the present invention.

According to the invention, a significant and, as a result, a remarkable improvement in the sieve efficiency (from, for example, 90% in conventional sieves to 98% according to the invention) is achieved solely by providing a compulsory mixture for the sieved material. This optimal compulsory mixing is achieved in that the mixer shaft is moved over the screen and the mixing elements engage in the screenings at progressive points. This forced mixing thus optimally mixes the material to be screened, so that the proportion of fine grain in the immediate vicinity of the sieve opening is increased again and the sieving efficiency is thereby improved. Mixing or compulsory mixing means u. a. also that, during the screening process, the material to be screened is continuously moved and mixed in sections and, if necessary, with different movement components and / or intensities at at least one or preferably several points. In other words, the most diverse areas of the material to be mixed are preferably at least in some areas and / or at times also with a movement component in the transverse direction of the main flow direction, with a component optionally also in the backward flow direction, with a movement component in from the sieve surface upwards or upwards the screen surface of the downward-facing component is circulated and thus ultimately mixed independently or essentially independently of the main flow direction.

klopfen". Durch dieses Anklopfen und durch die dadurch erzwungene Ausweichbewegung des Siebes nach unten hin werden die in den Siebmaschen befindlichen Teilchen (sog. Fische) gelockert und durch deren Trägheit aus den Sieböffnungen entfernt.In a preferred embodiment of the invention, the arrangement can be such that the rotating mixer elements during their orbital movement on the up and down pivoting of the screen

knock ". This knocking and the forced evasive movement of the sieve the particles in the sieve meshes (so-called fish) are loosened towards the bottom and are removed from the sieve openings by their inertia.

In a further preferred embodiment of the invention, in particular in the case of vibrating screens, the mixer or compulsory mixer (with its shaft) can be installed parallel to the main conveying direction of the screened material, which is then pushed or moved across the width of the screen by means of a suitable device, the mixer shaft rotating at a suitable speed and possibly alternating direction. Likewise, the mixer shaft can also be aligned transversely to the main flow direction, in which case the mixer shaft is preferably moved back and forth along the main flow direction.

In an alternative embodiment, the screening device, which is in particular equipped with a vibrating screen, can be equipped with one or more circular mixers, preferably with plow mixing elements. Such circular mixers can also be used in rotary screens.

In vibrating screens, for example, reciprocating brush rollers or even compulsory mixers installed transversely or parallel to the main conveyor device could loosen and mix the screenings, and at the same time keep the screen openings free. The same effect can be achieved in rotary screens by rotating brush rollers or compulsory mixers.

Only for the sake of completeness is it noted that the screen surface can in principle also remain immobile, the transport of the material to be screened over the screen surface being carried out or supported by suitably designed positive mixers. In this case, the screen surface is preferably inclined.

Figur 1 :

eine Seitenansicht eines Schwingsiebes;

Figur 2 :

eine Draufsicht auf das in Figur 1 dargestellte Schwingsieb;

Figur 3 :

ein Schwingsieb in Draufsicht in einem zu Figur 1 und 2 abgewandelten Ausführungsbeispiel;

Figur 4 :

ein weiteres Ausführungsbeispiel einer erfindungsgemäßen Siebvorrichtung in Draufsicht mit kreisenden Mischerbalken mit Pflugscharmischern;

Figur 5 :

eine Seitenansicht eines in Figur 4 dargestellten kreisenden Mischerbalkens oberhalb des Siebes;

Figur 6 :

eine schematische Vertikalquerschnittdarstellung durch ein Rundsieb; und

Figur 7 :

eine schematische Draufsicht auf das Ausführungsbeispiel gemäß Figur 4.

The invention is explained in more detail below on the basis of exemplary embodiments. The individual shows:

Figure 1:

a side view of a vibrating screen;

Figure 2:

a plan view of the vibrating screen shown in Figure 1;

Figure 3:

a vibrating screen in plan view in an embodiment modified from Figures 1 and 2;

Figure 4:

a further embodiment of a screening device according to the invention in plan view with rotating mixer bars with ploughshare mixers;

Figure 5:

a side view of a rotating mixer bar shown in Figure 4 above the screen;

Figure 6:

a schematic vertical cross-sectional view through a circular sieve; and

Figure 7:

3 shows a schematic top view of the exemplary embodiment according to FIG. 4.

In FIG. 1, a schematic representation of a screening device with two mixing devices 5 arranged offset in the main flow direction 1 of the material to be screened 3 is shown in a first exemplary embodiment in a side view and in a top view, which device is shown parallel to the main flow direction 1 via a device (not shown). and can be moved here.

The screenings 3 is from an inlet end 7 via the Sieve 9, ie the sieve surface 9 'moves to an outlet end 11. It is preferably a vibrating sieve, preferably a sieve provided with a linear vibrating exciter, also called a vibrating or vibrating sieve for short. As shown in FIG. 1, the screen can be inclined from its inlet end to its outlet end 7, 11 at an angle of, for example, more than 3 ° and preferably less than 25 ° or 15 °.

In the embodiment shown, the frame 13 of the screening device, i.e. In addition to the side frame 13 'on the side columns or supports 15, a shaft or mixer shaft 17 is arranged which extends horizontally at the same distance transversely, i.e. runs obliquely or perpendicular to the main conveying or longitudinal direction 1 of the screen. The motor drive device is not shown in detail. Furthermore, the mixer shafts 17 shown in FIGS. 1 and 2 can be moved over the screen surface, specifically in the main flow direction 1 and back. The sliding mechanism is not shown.

On the shaft 17 are in the radial direction protruding and in the longitudinal direction to the shaft 17 mixing elements 19 radially protruding. In the exemplary embodiment shown, the mixing members 19 are arranged in three rows, offset in the circumferential direction, in discrete steps, running over the longitudinal direction of the shaft 17. In the exemplary embodiment shown, the individual plate, shovel, sheet or sheet metal strips, paddle or ploughshare-shaped or other forms of mixing elements 19 are provided, which rotate clockwise or counterclockwise or with alternating rotation of the shaft in the illustration according to FIG. 1 Direction of rotation are driven and circulate. By means of the mentioned mixing elements 19, the material to be screened is not only loosened on its way along the main flow direction 1, when it passes through the relevant mixing device 5, but also, above all, shifted, that is to say, mixed. In this mixing, ie forced mixing process, the corresponding areas of the material to be screened 3 vary Movement and mixing components in deviation from the main flow direction 1, for example obliquely to the front, obliquely to the rear or in a right-angled transverse direction or in the backward direction, that is to say generally shifted and mixed in the longitudinal and transverse directions in the superimposed direction of the screened material. Mixing also produces movement components which are directed from the bottom upwards, ie away from the screen surface 9 ', but also towards the screen surface 9'. In any case, this compulsory mixing increases the proportion of fine grains in the immediate vicinity of the sieve 9, which increases the sieving effect.

Rechen- oder Pflugschar-Effekt". Durch diese unterbrochene bzw. im Seitenversatz zueinanderliegende Anordnung der Mischorgane wird zudem gewährleistet, daß grundsätzlich durch die Mischorgane selbst die Vorschubbewegung des Siebgutes insgesamt zu seinem Ablaufende hin grundsätzlich weiter möglich ist und durch die Mischorgane selbst nicht im Sinne einer Schranke und Barriere gestaut wird.Because the mixing elements are arranged in discrete steps on the relevant mixer shaft or the mixing element carrier, passage paths through the mixing elements also result continuously during the mixing, which increases the mixing effect. In other words, different sections of the at least one mixing element, or in the sense of the exemplary embodiments shown, several, for example, shovel or plow-type mixing elements, are immersed in the material to be mixed, with these mixing elements and the different locomotion and, if appropriate, rotation speeds of the mixing elements the material to be screened is optimally mixed and layered, and the material to be screened can pass between two adjacent mixing elements during the further drive movement of the mixing elements. This results in a kind

This interrupted or side-to-side arrangement of the mixing elements also ensures that the mixing elements themselves generally allow the feed movement of the material to be screened towards the end of its expiration and not in the sense of the mixing elements themselves a barrier and barrier is stowed.

The radial length of the mixing elements can be dimensioned such that during the circulation the front radial ends of the mixing elements touch the screen surface 9 ', i.e. Tap on the screen surface 9 'and book it down and bend it down at least slightly quickly and suddenly, at least for a short time, with this sudden tap knocking out the particles closing the mesh openings due to their inertia from their mesh openings upwards.

In the embodiment according to FIG. 3, only one mixing device 5 is provided, the shaft 17 of which, in deviation from FIGS. 1 and 2, in the longitudinal direction of the sieve, i.e. is provided running in the direction of the main flow direction 1, the shaft 17 being suspended transversely on the opposite end faces in the region of the inlet and outlet ends 7, 11 on a bridge running above the sieve 9 and the material to be sieved 3. In other words, the mixing device 5 is moved transversely to the main flow direction 1 from the left to the right edge of the sieve 9 and vice versa according to the arrow representation 21 in order to optimally shift and mix the material to be sieved again and again during the forward movement along the main flow direction 1 in sections .

In the illustration according to FIGS. 4 and 5, in the main flow direction 1 above the sieve surface 9 ', a revolving mixer bar 25 is shown rotatably suspended on a horizontal support 26, which is connected to the frame 13. , shovel etc. shaped mixing elements 19 are attached. The mixer bar 15 rotates about a vertical axis 27 - ie generally about an axis 27 which is perpendicular to the screen surface 9 '. The drive elements for this are not shown in detail. Through the in particular also in the representation according to FIG. 4 with respect to the longitudinal direction of the mixing bar 25, which is oriented at an oblique angle and possibly symmetrical to the central mixing axis 27, the scoop-like or plate-shaped mixing elements 19 are again adequately rearranged, loosened, that is to say with the most varied, along its forward movement in the main flow direction 1 Movement components completely mixed.

As a rule, it is sufficient if the radially projecting ends of the mixing elements 19 do not touch the actual sieve 9, but rather run past the sieve surface 9 ′ at a preferably small distance during the rotational movement. The distance can be varied and optimized according to the type of material to be screened as required. Distances of around 1 cm are sufficient. Improved the effect - as explained - when the radial ends of the mixing elements hit the sieve surface from above at least briefly during circulation, so that after the sieve surface is pivoted back into the starting position, the particles sitting in the sieve openings can be thrown out.

It is shown in FIGS. 1 to 3 that the various rows with the mixing elements 19, which are offset, for example, by 90 ° or 120 ° in the circumferential direction, can be aligned at the same distance, but offset from one another in individual rows. In the same way, the mixing elements in the longitudinal direction of the shaft 17 in question can only be provided offset at the same point in the circumferential direction.

6 and 7, in the schematic vertical cross section or in plan view, in deviation from the rectangular sieve surfaces 9 'explained above, a sieve device with a round, i.e. circular screen surface 9 'shown.

In this case, the material to be screened is fed along the arrow 35 to a funnel-shaped inlet end 7 arranged in the center of the circular screen 9 above the screen 9. In this embodiment, the outlet end 11 for the material to be screened is defined by the circumference, i.e. the outer boundary of the screen 9 is formed. There, along the arrows 37, the portions of the material to be screened which are not screened through the screen opening can flow outwards into a separate chamber (not shown further).

The entire sieve arrangement with the funnel-shaped inlet end 7 accessible in the middle from above can be covered by a cover 41 which, for example, together with the funnel-shaped inlet end 7 and the co-rotating device 5 housed therein. In the exemplary embodiment shown, two fastening bridges 31 are provided for the mixing device 5, which are connected radially on the inside to the funnel 43 forming the inlet end 7 and at their radially outer end to the cover 41 and rotate together with the latter about a central vertical central axis 45. On the fastening bridges 31 there are appropriately shaped mixing elements 19 which can end, for example, just above the sieve surface 9 '. The mixing element rotates about the vertical axis of rotation and symmetry 45, the material to be screened being constantly shifted and optimally mixed by the rotation of the mixing device during its migration from the center to the outer circumference (discharge end 11), i.e. along its main flow direction 1, which runs radially from the center to the outside the sieve effect is improved.

aufklopfen" um möglichen Verstopfungen entgegenzuwirken.The so-called horizontal and radial mounting bridges form the rotating shafts 17, so that a superimposed rotational movement once around a vertical axis of symmetry perpendicular to the screen surface 9 'and also around the radially projecting mixing organ support arms carrying the mixing elements 19, ie the mixer shaft 17 rotate. In the latter case, the lower ends of the mixing elements 19 could also be on the screen surface again

tap "to counteract possible constipation.

In the last-mentioned exemplary embodiment according to FIGS. 6 and 7, a vibrating or vibrating sieve (vibrating sieve) is generally also used, wherein in particular a circular oscillation or vibration can be generated, by means of which the material to be mixed radially outwards from its central inlet end 7 increasingly low screen material height drifts along the main flow direction 1.

Claims (17)

1. Sieve device comprising a sieve (9), particularly a flat sieve, and preferably comprising an oscillator for the sieve after the style of an oscillating or vibrating sieve, and comprising a rotation device which is arranged above the sieve surface (9') and which comprises mechanical elements mounted on a drivable shaft and dipping into the material to be mixed, characterized in that the rotation device is in the form of a positive-action mixing device (5) and for this purpose the rotating mixer shaft (17), together with the mechanical members in the form of mixing elements (19), can be moved over the sieve (9) during the sieving process.
2. Sieve device according to Claim 1, characterized in that the mixer shaft (17) extending substantially transversely to the main direction of flow (1) can travel parallel to the main direction of flow (1).
3. Sieve device according to Claim 1, characterized in that the mixer shaft (17) extending substantially parallel to the main direction of flow (1) can travel above the sieve surface (9') transversely to the main direction of flow (1).
4. Sieve device according to one of Claims 1 to 3, characterized in that at least two positive-action mixing devices (5) having two travelling mixer shafts (17) are provided.
5. Sieve device according to Claim 1, characterized in that the at least one mixer shaft (17) is in addition rotatable about a rotation axis (45) extending substantially at right angles to the sieve surface (9').
6. Sieve device according to Claim 5, characterized in that at least two mixer shafts (17), which are arranged radially relative to the rotation axis (45), are provided.
7. Sieve device according to Claim 5 or 6, characterized in that the rotation axis (45) extending substantially at right angles to the sieve surface (9') is in the form of a feed pipe or feed hopper (43), leading to the sieve surface (9'), for feeding the material (3) to be sieved.
8. Sieve device according to one of Claims 5 to 7, characterized in that the sieve (9) is in the form of a circular sieve.
9. Sieve device according to one of Claims 1 to 8, characterized in that the mixing elements (19) and the sieve (9) are arranged and constructed such that during the rotation of the mixer shaft (17) the mixing elements (19) come into contact with the sieve surface (9') and at least slightly deflect the latter downwards, preferably abruptly, so that, on completion of the reciprocal action of a rotating mixing element (19) and the sieve surface (9'), the sieve surface (9') moves back automatically to the starting position.
10. Sieve device according to one of Claims 1 to 9, characterized in that the direction of rotation of the mixer shaft (17) and/or of the mixing elements (19) can be changed.
11. Sieve device according to one of Claims 1 to 10, characterized in that the mixer shaft (17) and/or the mixing elements (19) can be driven with an alternating direction of rotation.
12. Sieve device according to one of Claims 1 to 11, characterized in that the mixing elements (19) are in the form of plates, blades, sheet or strip metal, paddles, ploughshares or brushes.
13. Sieve device according to one of Claims 1 to 12, characterized in that a multiplicity of individual mixing elements (19), arranged offset to one another in the longitudinal and peripheral directions, or only one, interrupted mixing element (19) forming paths for the passage of the material (3) to be sieved, are or is provided on the mixer shaft (17).
14. Accessory for a sieve device, characterized by a positive-action mixing device (5) according to one of Claims 1 to 13.
15. Sieving process utilizing a sieve device according to Claims 1 to 13 or an accessory for a sieve device according to Claim 14, characterized in that the material (3) to be sieved is mixed by a positive action on its path along its main direction of flow (1) or from its inlet end to its outlet end (7, 11), and for this purpose a mixer shaft carrying the mixing elements (19) is moved over the sieve and the mixing elements act on the material (3) to be sieved at progressive points.
16. Sieving process according to Claim 15, characterized in that the mixing of the material (3) to be sieved is effected a portion at a time or intermittently with a mixing and/or movement component transverse to the main direction of flow (1).
17. Sieving process according to Claim 15 or 16, characterized in that during the mixing process individual regions and portions of the material (3) to be sieved are moved with different movement and intensity components.

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