EP2532445A2 - Screening machine - Google Patents

Abstract

The device (1) has multiple adjacent screen shafts arranged rotatably, and a set of screen disks arranged at each screen shaft. The screen disks are separated from one another in an axial direction by clearances. The screen disks of the shaft engage in clearances of the screen disks of adjacent screen shafts, where the screen disks are provided with a cleaning device for cleaning the clearances between the screen disks of the adjacent screen shafts. One of the screen shafts is arranged as a multi-edge tube i.e. square tube, on which the screen disks are attached. The screen disks are made of rigid materials.

Description

The present invention relates to a screening device and a screening machine with a screening device for the screening of particular biomass and similar bulk materials or the like. The screening machine and the screening device can be used for a wide variety of purposes. One possible field of application is the screening of biomass for thermal utilization. In the combustion of biomass for heat or energy production, it is necessary to screen off the resulting biomass to supply the desired grain size fraction of the incinerator, while, for example, sand or similar particles are screened out beforehand, for. B. to reduce the ash content. Often it is still useful to sort out too large pieces to ensure a homogeneous and uniform combustion or to prevent disturbances in the conveyors of the incinerators.

Similar conditions apply to other uses, so it makes sense to divide the mass to be sifted into two, three or more fractions, one of which is further recycled, while waste such as sand or the like, for example, be deposited directly. Too large pieces can be crushed again and sieved again.

For screening of biomass, for example, star screens are used in which screen stars are mounted on parallel sieve shafts, which consist of elastic materials and projecting radially outward from the shaft sieve fingers exhibit. Due to the elasticity of the sieve fingers, the individual fingers can dodge flexibly if necessary. The screen stars of a screen shaft each engage in spaces between the screen stars of an adjacent screen shaft. During operation, the screen shafts rotate, thus conveying the material to be screened along the screening deck. Material to be sifted passes between the individual sieve fingers and is transported predominantly downwards by the rotation of the screen stars below the sieve deck if the material picked up between the fingers has sufficiently small dimensions.

Such star screens with screen elements made of elastic materials work reliably. The disadvantage, however, that the individual fingers of the screen stars need a certain spatial extent to ensure the required stability. This is why star screens made of elastic materials do not allow the screening of fine and finest components from biomass.

In the prior art disc screens or disc separators have become known in which a plurality of parallel arranged in a frame rotatably driven shafts are provided on which a plurality of discs are arranged in gap and interlocking. Such a screen is for example also from the EP 0861696 A1 known. In this known Scheibensieb or Scheibenseparator the arranged on the waves polygonal discs made of a ferrous material. Partial surfaces of the disk body are provided with an armor made of hard metal to increase the service life.

Thus, this known disk screen is basically also suitable for separating heavy screenable masses. Biomass is often a substance that is difficult to screen and has as well cohesive screenings also have a tendency to settle on the discs or on the shaft hubs and build up.

Metallic sieve discs enable the targeted screening of fine products. A disadvantage, however, is that in the screening of cohesive materials it can lead to increased adhesion of Siebguts to the discs and / or shaft hubs, which can lead to a lower screening performance and possibly to a blockage of the screen, if the required drive power above the Available drive power is.

That is why it is with the EP 0861696 A1 Also known to provide at each second corner of each disc scraper, which protrude laterally and free during the rotational movement of the discs, the gap between the discs and the surface of the shaft hub of caking. This state of the art works basically. The disadvantage, however, that a high energy consumption for the rotational movement of the disc screens is required by the high number of 5 scrapers per disc, since the scrapers must be constantly passed through the mass to be sifted. In addition, adhesions can occur when screening fine cohesive materials.

It is therefore an object of the present invention to provide a screening device and a screening machine with a screening device available, whereby the targeted screening of fractions low grain size is possible and wherein cleaning agents are provided to clean the spaces between adjacent screen discs, wherein also the Energy requirement is reduced.

This object is achieved by a screening device with the features of claim 1. The screening machine according to the invention is the subject of claim 15. Another screening machine according to the invention is the subject of claim 12. Preferred Further developments and refinements are the subject of the dependent claims. Further advantages and features of the invention will become apparent from the description of the embodiments.

The screening device according to the invention comprises a plurality of adjacent and rotatably arranged screening shafts, on each of which a plurality of sieve discs made of substantially rigid materials is arranged. The screen discs are separated from each other in the axial direction by a gap. Sieve disks of a screen shaft engage in interspaces of the screen disks of adjacent screen shafts. At least half of the screen disks at least one cleaning device for cleaning the spaces between the screen disks of adjacent screen shafts is provided.

The screening device according to the invention has many advantages. A significant advantage of the screening device according to the invention is that the screen discs consist of substantially rigid materials. Preferably, the screen discs are made of metallic materials, but they may also consist of inelastic plastics. By the construction of rigid materials, a more precise construction can be ensured, which also enables the screening of fine and finest fractions from biomass.

Material adhering to the screen disks or the screen shaft is removed again by the cleaning devices, which are arranged on approximately half of the screen disks. In this case, the cleaning device preferably comprises at least one and in particular exactly one extended cleaning tooth or is designed as such. In particular, exactly on each second screen disc exactly an extended cleaning tooth for cleaning the spaces between the screen discs of adjacent screen waves is provided.

The extended cleaning tooth allows an almost full-surface cleaning of the sides of the screen discs. The axial width of the cleaning tooth is preferably at least twice the axial thickness of the screen disc and in particular more than three times the disc thickness. In particular, cleaning teeth may be provided at the terminal screen disks of a screen shaft, which have a smaller axial width.

But it is also possible that a cleaning device comprises two or more extended cleaning teeth. The at least two cleaning teeth are preferably arranged angularly offset on the screen disk. If two cleaning teeth are provided, it is possible that each cleaning tooth projects substantially only on one side of the screen disk. It is also possible for at least one cleaning tooth of the at least two cleaning teeth not to be arranged axially in the middle of the screen disk. As a result, the cleaning tooth projects with a larger area on one side of the screen disk.

In particular, the at least two extended cleaning teeth of a screen disk are arranged such that they substantially cover the space to be cleaned between the screen disks of adjacent screen shafts. Such a design with two substantially half cleaning teeth is particularly advantageous because the complement at least two cleaning teeth in their cleaning effect and thereby the load acting on a cleaning tooth is reduced. Also foreign objects can be easily pushed out of the spaces between the sieve discs of adjacent sieve shafts. In particular, a blockade of individual screen waves or the entire screening device is reliably avoided.

Due to the rigid materials can be thinner wall thicknesses compared to the known screen stars on the screen discs be used from elastic materials. With the same grain size, a considerably larger open screen area is achieved. In addition, a finer screening result can be achieved as well as a higher throughput with a comparable screen area.

Preferably, the screen discs of the screening device are arranged to rotate in the same direction. As a result, the material to be screened is transported away from the feed point while simultaneously being screened.

Due to the fact that only one cleaning device with in particular only one cleaning tooth is provided as cleaning agent on each second screen disk, the energy consumption is considerably reduced during operation. For a total of two screen disks, only one cleaning tooth or only two substantially half cleaning teeth are provided, whereas in the case of the cited prior art two screen disks have a total of 10 wipers which must be constantly passed through the mass to be screened.

Particularly preferably, the cleaning devices are provided only on the screen discs about half of the screen shafts. This means that in an even number of sieve shafts exactly half of the screen shafts cleaning devices are provided. Since cleaning devices are only provided on every second screen shaft, cleaning devices are then provided on each screen disk of the corresponding screen shaft, while the screen disks of the other half of the screen shafts have no cleaning device.

If the total number of sieve shafts is an odd number, the number of sieve shafts equipped with sieve discs with a cleaning device may correspond to the rounded-off half of the total number of sieve shafts.

Accordingly, the total number of screen discs provided with cleaning means may also be slightly larger or slightly smaller than half of the screen discs as a whole.

However, sieve devices with an even number of sieve shafts are particularly preferably provided, so that the number of sieve discs provided with cleaning devices is 50% +/- 5% and in particular exactly 50%.

In a preferred development, at least one screening unit is provided which comprises a plurality of adjacent and in particular four adjacent screening shafts. If the sieve unit comprises four adjacent sieve shafts, cleaning devices are preferably arranged only on the sieve disks of the two middle sieve shafts. Such a configuration offers considerable advantages, since the cleaning devices of the screen disks of the two middle screen shafts can clean all interstices of the screen unit. As a result of the rotation of the cleaning devices, the spaces between the sieve disks of the outer screen shafts are also cleaned.

Advantageously, adjacent screen shafts of a screen unit at different speeds. Due to the fact that adjacent screen shafts of a screen unit have different rotational speeds during operation, it is ensured that not only the same location is swept by the cleaning device, but that during cleaning the cleaning device clears the gap between two screen disks over the entire circumference. The different rotational speeds ensure that the cleaning device cleans a different circumferential point of the corresponding gap with each revolution. After just a few revolutions of the sieve shafts, the entire circumference is cleaned, so that an accumulation of an adhering product layer can be reliably prevented.

Due to the consistent cleaning of the interstices, a uniform screening performance is ensured even in continuous operation and the sieve grain distribution of the sieved fraction is largely constant. Preferably, several adjacent screen shafts of one or more screening units are driven in a coupled manner. For example, the individual screen shafts can be connected to one another via chain drives. By the number of teeth of the individual pinion defined speed ratios of the individual sieve shafts can be guaranteed. At the same time slip is avoided by a chain drive, so that at any time defined angular positions of the individual screening shafts are ensured. This ensures that the cleaning devices of the two middle adjacent screen shafts do not collide with each other.

The dimensions of the extended cleaning teeth are adjusted to the speed ratios of the adjacent cleaning waves, that a complete cleaning of the gap between two screen discs is ensured while avoiding a collision of the cleaning teeth of the adjacent screen shafts.

It has been found that a speed ratio of two adjacent screen shafts of a screen unit between 7: 6 and 5: 2 is advantageous. Particularly preferred is a speed ratio of 4: 3 fixed. In this case, it can be ensured that the two intermeshing cleaning devices of the middle screen shafts in each case engage behind, if they have the smallest distance. At a speed ratio of 4: 3, the same constellation occurs every 4 or 3 revolutions.

In all embodiments, it is preferred that the rotational speeds of the screen waves increase or decrease in the transport direction of the screening material to be screened off. For example For example, the screening shafts of a second screening unit can have higher rotational speeds than the screening shafts of a first screening unit, wherein the speed ratios of the individual screening shafts in the individual screening units can be constant.

An increasing rotational speed of the screen waves in the transport direction of the screening device can be useful, for example, to achieve a screening result that is constant over the screen surface. In the task area of the screening device usually more abandoned material will be present, so that there the screened material is rather finer than at the end of the wire stretch, where at the same speeds, the fine material is a bit coarser. To counteract this, the shaft speed can be increased from the beginning of the Siebstrecke towards the end. For other materials or constellations, the same speeds or even speed reductions may make sense. By varying the rotational speed over the sieve length, such factors can be compensated.

In all embodiments, it is preferred if the screen discs and / or the cleaning devices are made of metal. The cleaning devices and / or the cleaning teeth preferably have at least one armor layer in order to reduce wear. Also possible is a suitable plastic or ceramic material.

In all embodiments, it is possible that at least one screen disc has at least one lateral recess and / or at least one axial through hole. Through axial through holes on at least one screen plate possible adhesions can be reduced to the screen discs. In addition, the total weight of the screening device is not significantly reduced. This is particularly - but not only - in transportable screening or screening machines advantage. In addition, the rotating mass is reduced, causing lower loads are applied to the drive and bearing elements. Therefore, a lower energy requirement is realized thereby.

Advantageously, at least one screen shaft is designed as a polygonal tube and in particular as a square tube.

At least one screen shaft may comprise an inner massively configured screen shaft and an outer tube or an outer screen tube. During assembly, the outer screen tube is pushed onto the inner screen shaft. The inner cross section of the outer sieve tube is adapted to the outer cross section of the inner sieve tube to ensure a positive connection. A certain play is possible to ensure a simple Aufschiebevorgang. For example, an absolute difference of inner dimension of the outer screen tube to the outer dimension of the inner screen tube of 0.5 mm or 1 mm or 2 mm or the like may be provided. It is also possible and preferred for the inner dimension of the outer screen tube to be greater than the outer dimension of the inner screen tube by between approximately 1% and 10% and in particular between approximately 2% and 5%. Before pushing on the outer sieve tube, the sieve discs are preferably attached thereto.

At the polygonal tube, the associated sieve discs are attached. For example, the screen discs can be held on the polygonal tube via positive locking. In addition, they can for example still be welded to the polygonal tube.

In all embodiments it is preferred that a plurality of mounting aids arranged in the axial direction are provided on at least one screening shaft. Such an assembly aid may for example be designed as a groove or comprise a circumferential ridge or a hole, a depression or a survey or the like. Preferably, the screen discs are aligned or arranged on the mounting aids. Particularly preferred form the screen discs with the mounting aids and / or the screen shafts bayonet each. Through the bayonet lock the screen disc is held defined on the screen shaft. Preferably, at least one sleeve is arranged in the intermediate space between two screen disks of a screening shaft. The sleeve is in particular firmly connected to a screen disc and preferably welded thereto. The sleeve in particular surrounds the polygonal shaft and serves to avoid adhering screen material on the polygonal shaft. The sleeve may for example have a round outer cross-section. However, it is also possible and preferred for the outer contour of at least one sleeve to be adapted to the movement profile of the cleaning devices. The movement profile of the cleaning devices depends in particular on the speed ratio of adjacent waves and can be formed, for example, as a rounded triangle or rounded quadrilateral. Depending on the speed ratio and rounded Mehrecken outer contours can be provided.

The sleeves may for example consist of stainless steel. Stainless steel has the advantage that biomass is usually poorly adhered to. But it is also possible to make the sleeve of other art or natural materials. It is also possible that the sleeve consists of a first material and is provided with an outer layer of a second material. Also possible is an additional coating with Teflon or the like.

In all developments and refinements, it is preferred that a deflector is arranged on the screen disk in the circumferential direction in front of the cleaning device. Such a deflector usually prevents, for example, a foreign object such as a stone or the like from blocking the cleaning device, since the deflector first contacts such a foreign body and thus conveys it to the side. This increases the reliability of the system again. In all embodiments, it is preferred that at least one screen disk is designed as a toothed disk having radially outwardly projecting teeth. The teeth of the toothed disc serve to transport the sieved product over the sieve surface and provide a loosening and distribution of the sieved product.

In all embodiments it is preferred that the lateral end shafts of the screening device are not provided with cleaning devices. Such a configuration allows a modular structure, since during the assembly of two screening devices on a screening machine, the cleaning devices of a screening unit do not protrude between the screen disks of the screening unit arranged next to it. Since the cleaning devices have only a lateral distance of about 1 or 2 or 3 mm to the adjacent screen disc, while the distance between two screen discs, for example, 10 or 15 mm, this allows a much simpler installation of multiple screening units to each other, as not mounted to 1 millimeter must be, but can be mounted on, for example, 5 millimeters exactly. At the same time, the screen accuracy on the surface is maintained, since the small and exact gap dimensions are maintained there. Because no cleaning devices are provided on the lateral end shafts, consequently, no collision of the cleaning devices can take place there if several sieve units are lined up.

According to another aspect of the invention, it is the object to provide a screening device which has screen discs on rotating screen shafts and which enables a high reproducibility of the construction and the assembly.

The background of this task is that the screens used are often heavy plates with a nominal sheet thickness for example, 3 or 4 millimeters, the tolerances of the sheets used allow significant deviations from the nominal sheet thickness. As a result, screen shafts having a multiplicity of, for example, 40, 50, 60 or more screen disks have different dimensions and must be adapted to one another in a complex manner.

The described object is achieved by a screening device which has a plurality of adjacent screen shafts rotating during operation. At the screen shafts, a plurality of screen disks spaced apart from one another in each case in the axial direction is arranged in each case. Screen discs of a screen shaft engage in the interstices of the screen discs of an adjacent screening shaft. At predefined axial positions of at least one screen shaft, at least one mounting aid for defined mounting of the screen disks is arranged in each case. The axial positions on the screen shaft are defined in each case from an origin point over an integer multiple of an axial distance.

The screening device according to the invention has many advantages. A significant advantage of this screening device according to the invention is that accumulating errors are avoided. The mounting positions of the respective screen discs are defined by a respective distance defined by an integer multiple of an axial distance from an origin point. This means that each position is first calculated from an origin point, so that the addition of a large number of tolerances is reliably avoided.

In the prior art, however, a first screen disc is applied to the screen shaft. Following this, a spacer is applied and a second screen disc is pushed on. Thereafter, alternating screen discs and spacers are applied, with the respective position the screen discs by the addition of the axial dimensions of all previously deferred parts results. Even if every single part has a high manufacturing accuracy, this manufacturing accuracy always has a tolerance, so that when "n" deferred parts, the tolerance has ver-n-facht. For 60 screen discs z. B. even at low manufacturing tolerances of, for example, 1/10 millimeters to a possible error of 6 millimeters. If now the screen discs of a first screening shaft are inserted between the screening discs of a second screening shaft, the distances of the screening discs must be correspondingly adjusted manually, which makes the production complicated and expensive.

The invention in turn provides a screening device in which an accumulation of different tolerances, errors and manufacturing inaccuracies is fundamentally avoided. The dimensioning and positioning of the individual screen discs does not take place via the positioning of the previously applied screen discs, but in each case absolutely from an origin point. This results in the lateral distance of a screen disc from an axial end of the screen shaft to a basic distance and the added to n times the distance between two screen discs. The maximum error is exactly one thickness tolerance of the screen disc and not 60 times the tolerance of a screen disc, if z. B. 60 screen discs are provided.

In all embodiments, the assembly aid preferably comprises at least one groove in the screen shaft and in particular in the outer screen shaft or in the outer polygonal tube. The groove may be performed circumferentially around the screen shaft. But it is also possible and preferred that the mounting aid has individual recesses, grooves or holes on the circumference of the screen shaft. If, for example, a groove, a hole or the like is used as an assembly aid, then all the holes or grooves can be used as an assembly aid even before the sieve disks are installed be introduced into the screening shaft. This can be done for example via an automated manufacturing process in which, for example laser-based corresponding markings or grooves or the like are introduced into the screening shaft.

Preferably, a holding finger is provided at least on a screen disc, which engages in the groove of the screen shaft. By such a configuration, a particularly reliable mounting is made possible, since the retaining finger engaging in the groove leads to a permanently defined axial and radial positioning of the screen disk.

In all embodiments, it is preferred that the screen disc cooperates with the mounting aid of the screen shaft in the manner of a bayonet closure.

In advantageous embodiments, at least one support finger is provided on the screen disc, which serves for support on the outer screen shaft.

Preferably, an outer screen shaft and an inner screen shaft are provided, wherein the inner screen shaft is made solid and the outer screen shaft is attached as a screen tube on the inner screen shaft. For this purpose, the inner cross section of the outer screen tube is adapted to the outer cross section of the inner screen shaft. Preferred are polygonal profiles such as a square.

In such an embodiment, the retaining fingers engage in the example executed as a groove or hole mounting aids in the outer screen tube, but without the wall to pass inward. This ensures that the outer screen tube can be pushed onto the inner screen shaft.

In all embodiments, it is preferred that a screening machine is equipped with at least one of the screening devices described above.

Further advantages and features of the present invention will become apparent from the embodiments, which are explained below with reference to the accompanying figures.

Fig. 1

eine perspektivische Ansicht einer transportablen erfindungsgemäßen Siebmaschine;

Fig. 2

einer perspektivische Ansicht einer feststehenden erfindungsgemäßen Siebmaschine;

Fig. 3

ein Siebdeck der Siebmaschine nach Fig. 1 oder Fig. 2;

Fig. 4

das vergrößerte Detail B aus Fig. 3;

Fig. 5

das vergrößerte Detail A aus Fig. 4;

Fig. 6

einen schematischen Längsquerschnitt durch eine äußere Siebwelle;

Fig. 7

einen vergrößerten Querschnitt durch die Siebwelle nach Fig. 6;

Fig. 8

einen Querschnitt durch eine Siebscheibe und die Siebwelle;

Fig. 9a

eine Siebscheibe mit einer damit befestigten Hülse in einer perspektivischen Ansicht;

Fig. 9b

eine andere Siebscheibe mit einer damit befestigten Hülse in einer perspektivischen Ansicht;

Fig. 10

eine perspektivische Ansicht einer weiteren Hülse;

Fig. 11

eine Draufsicht auf eine andere Hülse; und

Fig. 12

eine perspektivische Ansicht einer alternativen mit Siebscheiben ausgerüsteten Siebwelle.

In the figures show:

Fig. 1

a perspective view of a portable screening machine according to the invention;

Fig. 2

a perspective view of a fixed screening machine according to the invention;

Fig. 3

a sieve deck of the screening machine Fig. 1 or Fig. 2 ;

Fig. 4

the enlarged detail B off Fig. 3 ;

Fig. 5

the enlarged detail A from Fig. 4 ;

Fig. 6

a schematic longitudinal cross section through an outer screen shaft;

Fig. 7

an enlarged cross section through the screen shaft after Fig. 6 ;

Fig. 8

a cross section through a screen disk and the screen shaft;

Fig. 9a

a screen disc with a sleeve attached thereto in a perspective view;

Fig. 9b

another screen plate with a sleeve attached thereto in a perspective view;

Fig. 10

a perspective view of another sleeve;

Fig. 11

a plan view of another sleeve; and

Fig. 12

a perspective view of an alternative equipped with screen discs screen shaft.

With reference to the enclosed Figures 1 - 12 In the following exemplary embodiments, screening machines 100 with screening devices 1 according to the invention are described which are each designed as a toothed disc screen 105.

Fig. 1 shows a perspective view of a designed as a mobile screening machine 110 screening machine 100, which can be taken over transport hooks 103 to transport the screening machine 100, for example, with a truck. The portable screening machine 110 may also have wheels and be designed as a trailer or self-propelled.

The screening machine 110 off Fig. 1 has a screen deck 104 with two Zahnscheibensieben 105. The first toothed disc screen 105 is arranged in the feed area, which adjoins the feed bin 102. The Siebdeck 104 is another toothed pulley 105 downstream. The Zahnscheibensiebe 105 is used for screening of sand and similar particles from the sieved mass or biomass. The screened fine material 112 falls downwards and is transported away via the discharge belt 107.

From the in Fig. 1 Screening shafts not shown in detail with the screen discs 8 and 9 of the toothed disc screen 105 arranged thereon are used to transport the applied material away from the receiving bunker 102 while the fine material 112 is screened off.

The coarse material 114 is discharged onto the discharge belt 108 at the end of the second toothed disc sieve 105 and transported away.

In Fig. 2 is a highly schematic and perspective view of a designed as a fixed screening machine 1 screening machine 100 shown. The abzusiebende material is abandoned, for example, with a wheel loader in the hopper 102 and passes through the conveyor belt 109 on the screen deck 104, which is equipped with a toothed pulley 105 as a screening device 1. The Zahnscheibensieb 105 will be explained in more detail with reference to the following figures.

In the first part of the screening machine 111, the fine material 112, such as sand and the like, passes down through the toothed disc 105 and can be removed there, for example, again with a wheel loader or the like. The payload is screened in the second part, while the too large coarse material 114 is delivered at the end.

The housing 101 of the screening machine 100 can in principle be of any desired design.

Fig. 3 shows in an enlarged plan view formed as Zahnscheibensieb 105 screen deck 104 of the screening machines Fig. 1 and Fig. 2 , The Zahnscheibensieb 105 includes a plurality of screen shafts 2-5, which are arranged parallel to each other. Each screen shaft 2 - 5 is equipped with a plurality of screen discs 8 or 9, which are axially spaced on the screen shafts 2-5 are provided.

A schematically drawn motor 25 serves to drive. The individual screen shafts are rotatably coupled to each other via pinions 30, 31 and chains 26, 27. It can also be provided two or more engines.

The Zahnscheibensieb 105 consists of several screening units 12 and 13, which are connected in series in the transport direction of the material to be screened.

Fig. 4 shows the detail "B" Fig. 3 in a further enlarged view. The total of four waves 2-5 of the sieve unit 12 are shown. The screen shafts 2 and 5 are equipped with screen discs 9, which are designed as toothed disks 29. The middle screening shafts 3 and 4 are provided with screen discs 8, which are designed as toothed disks 28. Between the individual sieve discs 8 and 9 of the individual screening shafts 2-5, intermediate spaces 7 are respectively provided in the axial direction of the shafts into which the adjacent sieve discs 8 or 9 of the adjacent sieve shafts dip.

To remove caking material from the surface of the screen discs 8 and 9 and the surface of the screen shafts, cleaning means 50 are provided. A cleaning device 50 here comprises a cleaning tooth 11 as a cleaning agent 10. The cleaning teeth 11 are arranged only on the screen disks 8 of the middle screening shafts 3 and 4. In each case exactly one cleaning tooth 11 is provided on each screen disk 8 of the middle screening shafts 3 and 4. At the screen disks 9 of the outer screening shafts 2 and 5 no cleaning teeth are provided.

Due to this type of construction, in principle any number of screening units 12 can be arranged one after the other in order to provide a correspondingly large screening area. Characterized in that the sieve discs 9 of the screening shafts 2 and 5 are not equipped with cleaning teeth 11, there is no risk of collision of the cleaning teeth 11 adjacent screening units 12 in the installation of adjacent screening units 12th The requirements for the assembly accuracy is significantly reduced, without the screening result practically influence. In addition, adjacent screening units 12 can be operated at different speeds.

In the in Fig. 4 The cleaning teeth 11 clean the gaps 7 on the screening shaft 2 and the screening shaft 5. During operation, the screening shafts 2 - 5 continue to rotate, so that during further rotation the cleaning teeth 11 clean the spaces 7 on the screening shafts 2 and 3. The cleaning teeth 11 of the screening shaft 3 clean the interspaces of the screening shafts 2 and 4 during the rotating operation. The cleaning teeth 11 of the screening shaft 4, on the other hand, clean the interspaces 7 on the screening shafts 3 and 5 during the rotating operation. This ensures that all intermediate spaces 7 of the screening unit 12 be cleaned in the course of several revolutions of the screening waves 2 - 5. If the product to be sifted off settles on the surfaces of the sieve discs 8 and 9 or the sleeves 20, this adhesion is released again in the course of a few turns.

The detail "A" off Fig. 4 shows Fig. 5 , Shown is the screen shaft 4 with the screen discs 8 arranged thereon, which are equipped with cleaning teeth 11. The cleaning teeth 11 serving as cleaning agents 10 leave only small axial distances between the screen disks 9 and the cleaning teeth 11, so that reliable cleaning can be ensured.

The screen discs 8 and 9 are arranged in the axial direction 6 each with a defined distance from each other.

Fig. 6 shows the outer shaft tube 39, for example, the screen shaft 2. The outer shaft tube 39 here has mounting aids 17 in the form of holes or grooves 18 which are provided at the four corners of the square profile here. The mounting aids are arranged at equal axial distances 22 to each other. The outer shaft tube 39 is a polygonal tube 15th and formed here as a square tube 16 and can serve as an outer shaft tube of the waves 2-5.

The inner shaft tube 40 of the individual screen tubes 2 - 5 has an outer contour which is adapted to the inner contour of the outer shaft tube 39, so that after pushing the outer shaft tube 39 on the inner massively executed screening shaft 40, a positive connection is formed.

In Fig. 7 is a cross section of the outer screen shaft and the outer shaft tube 39 from Fig. 6 shown. The outer shaft tube 39 is received in the mounted state of the inner shaft tube and the inner screen shaft 40.

Fig. 8 shows a screen disc 8, which is connected to the outer shaft tube 39.

On the inner contour of the toothed disc 8 (and also the toothed disc 9) holding fingers 23 and support fingers 24 are provided. After sliding a toothed disc 8 or 9 on the outer shaft tube 39 and the positioning of the mounting aid 17 in the form of grooves 18, the toothed disc 8 is here clockwise rotated by about 20 degrees until the retaining fingers 23 engage in the mounting aid 17 serving as grooves 18 , The retaining fingers 23 are dimensioned so that they do not or only very slightly protrude inwards. This allows easy sliding onto the inner screen shaft.

If the retaining fingers 23 protrude further inwards, z. B. longitudinal grooves may be provided on the outer surface of the inner screen shaft to allow the sliding of the outer shaft tube 39 on the inner shaft tube.

In any case, with the mounting aids 17 in the axial and radial direction fixed seat of the toothed disc 8 at a guaranteed and in particular predefined position guaranteed. By the rotational movement of the toothed disc 8 and 9 by about 20 degrees, the support finger 24 applies to the outside of the outer tube 39 and is supported there.

After such a positioning, the toothed disc 8 or 9 is welded to the outer tube 39 with a weld 37.

In operation, the timing pulleys 8 rotate in the orientation according to Fig. 8 counterclockwise, so that the loads occurring by the support fingers 24 via the outer shaft tube 39 on the solidly formed screening shaft 40 (FIG. Fig. 7 ) so that high and highest loads can be absorbed and deduced.

The rotating teeth 34 of the screen disk 8 designed as a toothed disk 28 cause a turbulence and a transport of the discontinued material to be screened in the longitudinal direction of the screening device 1. The cleaning tooth 11 ensures a cleaning of the intermediate spaces 7 between the individual screen disks.

Fig. 9a shows a perspective view of the screen plate 8 Fig. 8 , The cleaning tooth 11 is designed to be expanded both in the radial direction and in the axial direction and has an axial width which is slightly smaller than the axial distance between two screen disks of a screening shaft. The lateral distance between the cleaning tooth 11 and the screen to be cleaned 8 and 9 is usually about 1 to 1.5 millimeters. The axial width of the cleaning tooth 11 is preferably between about 4 and 25 mm. The radial length is preferably more than 5 mm and can reach 10 mm or 20 mm.

The sleeve 20 is fixedly connected to the screen disc 8 and, for example, welded thereto. The sleeve 20 is finished mounted state of the entire screening device 1 only firmly connected to a screen plate 8, and not with the axially adjacent screen disc. The sleeve 20 is not used for positioning the screen discs 8 or 9, but only to prevent caking on the screen shaft 2-5.

In Fig. 9b another screen plate 8 is shown in perspective. The cleaning device 50 here comprises two cleaning teeth 11, which with a smaller axial width than the cleaning tooth 11 in Fig. 9a are executed. A cleaning tooth 11 protrudes here substantially only to one side of the screen plate 8 or stands out. As a result, a cleaning tooth 11 cleans only about half of the interspace of two screen disks 8 or 9 of adjacent screening shafts 2-5. This advantageously reduces the load acting on the cleaning teeth 11 and thus also the wear of the cleaning teeth 11.

Since the cleaning teeth 11 complement each other in their axial width, a comparable cleaning performance as in the previously in Fig. 9a achieved single cleaning tooth 11 achieved. The arrangement of the cleaning teeth 11 on the screen plate 8 at different angular positions allows foreign bodies a larger space to escape from the gap, which also reduces the load on the cleaning teeth 11.

10 and 11 show further embodiments of the sleeves 20, which have a non-circular outer cross-section. The outer contour 21 of the sleeves 20 according to Fig. 10 or 11 is in each case adapted to the movement of the cleaning tooth 11, so that the least possible uncleaned space for caking remains.

Since adjacent screening shafts 2-5 of a screening unit 12 are operated at different rotational speeds, the relative point of engagement of a cleaning tooth changes with each revolution 11 in the corresponding space 7, so that over time the gap 7 is substantially cleaned over its entire circumference. The corresponding contours are for the ratio of speeds 3: 4 in the 10 and 11 shown. In the embodiment shown here, the rotational speeds of the screening shafts 2 to 5 are about 150 revolutions or 200 revolutions / minute. Also possible are larger and smaller speeds.

Fig. 12 shows an alternative embodiment of a screening shaft with sieve discs 9, wherein the sieve discs have through holes 14. The through holes 14 reduce the total weight of the screening device 1 considerably. In addition, less area remains for buildup of product to be sifted.

Overall, an advantageous screening machine with an advantageous screening device is provided, whereby a reliable and permanent operation can be ensured by the targeted cleaning of the interstices. Blockages due to adhering screenings can be largely avoided. In addition, the assembly is facilitated because the screen discs 8 and 9 are mounted in axially defined positions. By attaching mounting aids defined positions are possible. Furthermore, the energy requirement is reduced.

LIST OF REFERENCE NUMBERS

1

screening

2

screen shaft

3

screen shaft

4

screen shaft

5

screen shaft

6

axial direction

7

gap

8th

screen disc

9

screen disc

10

cleaning supplies

11

cleaning teeth

12

screening unit

13

screening unit

14

Through Hole

15

Polygonal tube

16

Square tube

17

mounting aid

18

groove

19

bayonet catch

20

shell

21

outer contour

22

distance

23

holding fingers

24

support fingers

25

engine

26

Chain

27

Chain

28

toothed washer

29

toothed washer

30

pinion

31

pinion

32

position

33

position

34

tooth

35

groove

36

inner contour

37

Weld

38

deflector

39

outer shaft tube

40

inner screen shaft

50

cleaning device

100

screening machine

101

casing

102

feed hopper

103

transport hook

104

Screendeck

105

Lock-washer Screen

106

starscreen

107

Austrageband

108

Austrageband

109

conveyor belt

110

Mobile screening machine

111

Fixed screening machine

112

fines

113

useful material

114

coarse material

Claims (15)

Sieve device (1) with a plurality of adjacent and rotatably arranged screening shafts (2-5), on each of which a plurality of sieve discs (8, 9) of substantially rigid materials is arranged, wherein the sieve discs (8, 9) each in the axial direction ( 6) by a gap (7) are separated from each other and wherein screen discs (8, 9) of a screening shaft (2-5) in intermediate spaces (7) of the screen discs (9, 8) adjacent sieve shafts (2-5) intervene,
characterized,
in that at least half of the screen disks (8) at least one cleaning device (50) for cleaning the intermediate spaces (7) between the screen disks (8, 9) of adjacent screen shafts (2-5) is provided. Screening device (1) according to claim 1, wherein the cleaning device (50) comprises at least one extended cleaning tooth (11). Screen device (1) according to at least one of the preceding claims, wherein at least one screen unit (12) is provided which comprises a plurality of adjacent and in particular four adjacent screen shafts (2-5), wherein only on the screen discs (8) of the two middle screen shafts (3 , 4) cleaning devices (50) are arranged. Screen device (1) according to the preceding claim, wherein adjacent screen shafts (2, 3, 4, 5) of a screen unit (12) have different rotational speeds during operation. Screening device (1) according to at least one of the preceding claims 3 and 4, wherein the speed ratio of two adjacent screening shafts (2, 3, 4, 5) of a screening unit (12) is between 7: 6 and 5: 2 and in particular fixed at 4: 3 is set. Screening device (1) according to at least one of the preceding claims 3 to 5, wherein the screening shafts (2-5) of a second screening unit (13) have different rotational speeds than the screening shafts (2-5) of a first screening unit (12). Screen device (1) according to at least one of the preceding claims, wherein at least one screen shaft (2-5) is designed as a polygonal tube (15) and in particular as a square tube (16) on which the associated screen discs (8, 9) are attached and / or wherein in the intermediate space (7) between two screen discs (8) of a screening shaft (2-5) at least one sleeve (20) is arranged. Screen device (1) according to the preceding claim, wherein an outer contour (21) of at least one sleeve (20) is adapted to the movement profile of the cleaning devices (50). Screening device (1) according to at least one of the preceding claims, wherein at least one screening shaft (2-5) a plurality of axially arranged (6) defined assembly aids (17) are provided, on which the screen discs (8, 9) via a bayonet closure ( 19) are kept defined and fixed in particular via a weld. Screen device (1) according to at least one of the preceding claims, wherein a deflector (38) is arranged on the screen disk (8) in the circumferential direction in front of the cleaning device (50) and / or at least one screen disk (8, 9) is provided as toothed disk (28, 29) is executed. Screen device (1) according to at least one of the preceding claims, wherein no cleaning devices (50) are provided on the end shafts (2, 5). Sieve device (1) with a plurality of adjacent and rotating in operation Siebwellen (2-5), in each of which in the axial direction (6) a plurality of spaced apart by a space (7) screen discs (8, 9) is arranged, said screen discs ( 8, 9) of a screening shaft (2-5) engage in the intermediate spaces (7) of the screening disks (8, 9) of an adjacent screening shaft (2-5),
characterized,
that at predefined axial positions (32, 33) of at least one screen shaft (2-5) at least one mounting aid (17) for defined mounting of the screen discs (8, 9) is arranged, the axial positions (32, 33) on the screen shaft (2-5) are each defined from an origin point over an integer multiple of an axial distance (22). Sieve device (1) according to the preceding claim, wherein at least one mounting aid (17) comprises at least one groove (18) in the screening shaft (2-5) and the screen disc (8, 9) with the assembly aid (17) of the screening shaft (2). 5) in the manner of a bayonet closure (19) cooperates. Screening device (1) according to one of the two preceding claims, wherein at least one holding finger (23) and / or at least one supporting finger (24) is provided on at least one screen disk (8, 9), wherein the holding finger (23) is inserted into the groove (18 ) of the screening shaft (2-5) engages and the support finger (24) is designed and suitable for radial securing on the screening shaft (2-5) in the load direction. Screening machine (100), wherein at least one screening device (1) according to at least one of the preceding claims is provided.

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