EP0584302B1 - Device for plansifter - Google Patents

Abstract

The sieve box (1) and sieve frame (3) have matching strip dividers (12') pref. for a two-side fines discharge. The sieve frame can have additional transverse dividers (13) forming several fields, and a corresp. number of cleaning elements (6) are provided. The sieve frame pref. has the lowest possible height and is designed as a freely interchangeable insert frame, typically of metal. The sieve box can be made of wood forming an outer frame with 1 to 3 ducts. The surfaces, contacting the prod. are coated with plastics, and the base plate of the box can be made of metal or plastics. <IMAGE>

Description

Technical field

The invention relates to a device for plan sifter consisting of a plan sifter, which has a screen box with base plate and fine material discharge, an insert screen frame and freely movable cleaning elements.

A plan sifter, especially the large plan sifter or square plan sifter, is a large cube shape with large surface elements and is a special separating device, which is characteristic for the sifting of grist-like, semolina and flour-like products in the milling process technology, and for sorting different types of grains such as wheat, Rye, corn, barley, etc. is used.

State of the art

In many separation techniques, for example in chemical process engineering, it is known to reduce the product moisture, if necessary, so that the separation devices do not become clogged. In contrast to this, optimum grinding moisture must be sought for the processing of cereal flour products, to make flour, semolina, mist, etc., but because grinding and sifting have to be carried out repeatedly in a cereal mill, the moisture depends on the grinding and not on the best possible visual effect .

It is known that many grinding fractions have poor flow behavior or visual behavior due to the high humidity, as can also be experienced in connection with flour sieving in the domestic kitchen.

All possible sizes of mesh sizes are used in a plan sifter, from the finest, for example 80 microns, to the coarsest. The same applies to everyone, without any sieve mesh clogging, to achieve the maximum visual performance. The highest possible throughput and the highest possible quality of the ground products must be achievable. In contrast to the classic sieving technique, a closed product layer of up to several centimeters is maintained with the miller sifting over the sieve covering. This ensures that a greater downward pressure (gravity) acts on the finer, heavier parts against the screen covering, which leads to a higher throughput or more screening capacity. On the other hand, more flat shell parts than coarse material should float off with the layer as a top screen. This type of "thick-film sifting" brings greater difficulties to the wet products and harbors a strong tendency to clog the screen fabrics.

Over the past 100 years, more efficient plan sifters have been systematically developed and screen cleaning has been continuously improved. Countless variations of shapes and materials have been tested and partly used in practice. Few shapes have survived in large-scale plansifters, although interestingly 5 to 10 centimeters long textile belt pieces with a metal button in the middle have been widely used for screen fabric cleaning. The screen fabric cleaners are individually between the screen fabric covering and inserted or locked a support grid. The underside of the sieve frame is therefore covered with a metal grid, which is the support for the sieve fabric cleaner. The metal grille usually has a slight ripple, so that the metal button receives strong impacts from the metal grille. Due to the oscillating or circular movement of the entire plan sifter, the belt piece is given a rattling and noise-generating intensive traveling movement. In this way, the mesh openings with the fringed ends of the belt pieces are kept free or clean. The metal grille and the metal button have an important function for the movement of the screen cleaner. As a disadvantage, the movement also creates an audible noise. Sieve cleaning pieces made of plastic in various forms are also known and work in the same way.

Another problem in plansifters is that the base plate is kept completely free. The fine material (diarrhea) that has fallen through the sieve mesh should be cleared from the base plate with the shortest possible dwell time and discharged through side slots. A separate category of cleaning elements, the so-called floor cleaners, was also developed for this. Common shapes are triangular and quadrangular, rhombus or polygon shapes.

Many factors influence the way the plansifters work. For example, a freshly covered sieve frame regularly works better, since not only the wear of the covering but also the degree of tension in the sieve fabric is important. Experience shows, however, that a plan sifter has natural performance limits even in the best condition. The intensity of the oscillating movement, i.e. the maximum acceleration, is also limited, on the one hand by maximum permissible forces in the plan sifter housing, and on the other hand by the movement behavior of the goods. Accelerating forces that are too strong impede the free flow of the material. Depending on the specific quality of the individual visual fractions, the performance data are given.

In DE-AS 25 06 981 it is proposed to give the base plate a sawtooth-shaped surface, so that product removal should take place in a very short time by means of appropriate impact forces. In very specific cases, it is entirely conceivable that the advantages will be achieved, but a larger market launch of a corresponding solution has not become known. It would be expected that particularly difficult, fine grinding fractions would clog the base plates or the sieve box very quickly. In a mill, the plan sifter is the machine that requires the greatest effort in terms of cleaning. In recent times, great importance has been attached to the fact that the processing machines are as self-cleaning as possible, but can be cleaned easily and with little effort if necessary.

From EP-A-0 330 846 a device for plan sifter is known, consisting of a plan sifter screen which has a screen housing with fine material discharge, an insert screen frame and freely movable cleaning elements, the screen frame being provided with a one-sided covering only and having at least one direction of dividers to form a corresponding number of cleaning fields for sieve and base plate, wherein the cleaning element or elements lying on the base plate can also be inserted into the cleaning field or fields.

The screen frames of plan sifter screens today have a smooth bottom on which freely movable floor clearers rest. Between the bottom and the covering of the sieve there are usually corrugated grids or supporting gratings for supporting Cleaning elements arranged. However, EP-A-330 846 also discloses designs free of corrugated mesh.

The cleaning elements can e.g. braided belt material, which is provided with a metal button on the underside and which start to vibrate when moving over the corrugated grille, so that they do not hit the screen fabric and clean it. This also causes a significant level of noise.

However, other forms of cleaning elements are also known, such as Screen cleaner in the form of equilateral triangles (US-PS 2,086,199) u. Like. According to EP-A-330 846, screen cleaners of this type can also have the outline shape of a three-armed star, without the use of corrugated grids, and consist of elastic material.

Presentation of the invention

The object of the invention was now to develop a concept which, for a given screen box volume, allows performance to be increased, but which is intended to improve handling and cleaning and also production.

The solution according to the invention is characterized in that the screen frame is provided with a covering on only one side and preferably has web strip subdivisions at least in one direction, for the formation of a Corresponding number of cleaning fields for screen and base plate, the cleaning element (s) lying on the base plate being or being insertable into the cleaning field (s). Here, a sieve housing is designed without connecting elements in the form of a sieve box with a base plate, in which the sieve frame is inserted in a form-fitting manner, the sieve frame being designed without connection elements in the form of a sieve box with a base plate. The inherent rigidity of the sieve frame is sufficiently large to absorb the forces that occur with only one-sided sieve covering without significant deformation.

As is well known, the numerous sieve coverings have to be changed and the defective sieves replaced due to the diagram. For this purpose, a correspondingly large number of reserve sieve frames are kept ready for use outside the plan sifter so that they can be replaced quickly.

• ein rascher Wechsel der Siebrahmen,
• ein rasches Wechseln der Siebreiniger,
• leichtes Reinigen des ganzen Plansichtersiebes,
• eine Leistungssteigerung für den Plansichter,
• die Verkleinerung der Bauhöhe,
• Vereinfachung der Herstellung (keine Verbindungselemente wie Schrauben u. dgl., Klebetechnik)
• Verbesserung des Verschleissverhaltens, sowie
• eine wesentliche Verbesserung in Sachen Sanitation.

The previous common opinion in the professional world was that a targeted, independent optimization of the screen fabric cleaning and the floor clearance must result in a maximum result. The invention has now proven the opposite. By merging the space of the previous screen fabric cleaners and the space of the floor cleaners, the resulting cleaning area can be chosen as a free diarrhea and product discharge area larger than either of the two, but smaller than the two together. In this way, the effectiveness for both functions is increased, which, in addition to a favorable design of combined cleaning elements, is one of the key points for the surprisingly positive visual effect, or for increasing the visual performance with identical visual quality. However, several problems could be solved very advantageously at the same time in a completely surprising manner. These are in particular:

• a quick change of the sieve frame,
• a quick change of the screen cleaner,
• easy cleaning of the entire plan sifter screen,
• an increase in performance for the plansifter,
• the reduction of the overall height,
• Simplification of production (no connecting elements such as screws and the like, adhesive technology)
• Improvement of wear behavior, as well
• a major improvement in sanitation.

The invention allows a number of particularly advantageous configurations. In the case of subdivisions, the sieve box and sieve frame preferably have corresponding web strip subdivisions, for a two-sided fines product discharge. The sieve frame can be provided with additional transverse subdivisions to form a plurality of cleaning fields and a corresponding number of cleaning elements, for example 2-9, preferably 6-12, cleaning fields with a preferably approximately square shape. It is also proposed to design the sieve frame with the smallest possible height dimension as a freely exchangeable insert sieve frame. The insert screen frame is very particularly preferably designed as a metal frame, especially as an aluminum or light metal frame. The new insert screen frame should have sufficient inherent rigidity. Even without a screw connection to the sieve box, the forces that arise due to the one-sided sieve covering should not cause any deformation of the insert sieve frame. But you get several advantages at the same time. The insert sieve frame can now be easily cleaned for the first time because it can be easily removed from the sieve box and especially because the sieve mesh can now be cleaned on both sides with little effort, for example by brushing or compressed air. If the insert frame is made of metal, this part can also be treated completely separately with water, hot steam, etc., which was previously difficult due to the wooden construction.

For handling, it is very advantageous if the sieve frame with the sieve fabric closes the sieve box flush at the top. The result is a clean tension of the stacks and stable stacks.

However, it is also possible to design the insert screen frame as a metal-wood composite, but this is disadvantageous in terms of cost. The sieve frame and sieve box are preferably matched to one another in such a way that the former can be placed or inserted loosely on or in the sieve box, with a quick clamp connection possibly having certain advantages.

The screen frame is advantageously made of light metal profiles as a welded joint. The sieve box is designed in a manner known per se as a dimensionally stable and dimensionally stable wooden frame and has 1 to 3 lateral channels, the surfaces in contact with the product preferably being coated with plastic. In contrast, the bottom plate of the metal sieve frame, i.e. Metal sheet can be made. In special cases, the base plate can also be made of plastic.

Such a screening device also includes corresponding cleaning elements known per se, which can be inserted into the clearing fields lying on the base plate. The cleaning element is provided with a wobble foot, which is preferably arranged in the region of the vertical axis of gravity of the cleaning element, for the purpose that a constant change of screen fabric cleaning and clearing of the floor takes place due to the corresponding wobbling movements.

According to a first embodiment, the cleaning element is designed as a boomerang with two projecting arms, which have cleaning agents for the screen fabric protruding upwards, a floor and slot clearing nose preferably being arranged on the cleaning element, opposite to the projecting arms.

According to a second embodiment, it is designed with 3 arms, with at least two arms at the top cleaning agents for the screen fabric, and one arm has a bottom and slot clearing nose which is extended outwards.

According to a further embodiment, it is designed with 4 arms, at least one arm having an elongated bottom and slot clearing nose.

In all configurations, however, it is very important that it is made of resilient material, preferably of plastic without metal. This ensures that with each impact of an arm on the side parts of the screen box or on the web strips, the screen cleaner is thrown in any direction via the corresponding spring force. By means of corresponding uninterrupted movements, including the wobble movement, it is statistically seen that every batch, be it the base plate or the screen fabric, is cleaned with great frequency. Even the smallest quantities of fine goods are transported away. The sieve cleaner should be selected so large that it has a certain mass and, with its largest horizontal dimension, is more than 50% of the correspondingly smallest dimension of the individual clearing fields. An optimal cleaning effect has also resulted in all tested shapes if the clearing fields formed have a square shape in the floor plan, if possible, since then the screen cleaners can clean optimally in all spatial directions or quickly clear out the product.

The previous optimal function was obtained when the arms have a cross-section with a roof-like elevation, with the tip up and the wide part down. This not only supports the product movement over the base plate, but also helps that the screen cleaner stays clean even without product buildup. The arms preferably have different cleaning agents, for example bristles or knobs and / or cleaning ribs. Floor cleaning is optimal if a sliding foot is only arranged on one arm.

The screen cleaner should be built slightly lower than the free height between the floor and the screen covering. In order to Despite the fact that the bottom and screen fabric are processed in the same way, the screen cleaner is provided with a wobble foot in the middle area, so that the extreme ends of the arms next to the horizontal movement of the screen cleaner above the floor in a constant interplay of up and down movements, up and down , edit both levels.

Another embodiment is that the arms are provided with a plastic impact head at their extreme ends. On the one hand, this serves as protection for the fabric cleaning agent in the form of knobs or brushes, on the other hand, it enables the sieve frame to be as low as possible, and it supports the jumping movement of the sieve cleaner so that the element is not damaged.

Furthermore, the device has a plurality of sieve stacks arranged in a top view housing, each of which consists of a larger number of sieve boxes with base plate, sieve frame and sieve channels and have a rectangular or square shape, the sieve frames covered with sieve fabric in relation to the sieve box are interchangeable and the sieve box above the base plate together with the sieve frame form free diarrhea and product discharge spaces can be inserted into the sieve cleaner, lying on the flat base plate, the sieve frame being designed to be rust-free to reduce the sound pressure from the source noise.

Since it was previously not possible to significantly reduce the noise of a large plan sifter, surprisingly, a noise level of only a little more than 72 dB (A) resulted in a plan sifter according to the invention, compared to 84 dB (A) in comparable plan sifters of the prior art . An important measure is seen in the choice of special screen cleaners, preferably made of non-metal material, and the screen frame without the previous metal support grids for screen screen cleaners. There are no longer any relative movements from metal to metal.

The invention is explained in more detail below using several exemplary embodiments.

Brief description of the invention

die Figur 1

einen Siebrahmen in einer Auflegebewegung auf einen Siebkasten;

die Figur 2

ein Grundriss eines Siebkastens mit eingelegtem Siebrahmen, teilweise ohne Siebgewebe;

die Figur 3

einen Schnitt a-a der Figur 2;

die Figur 4

einen Schnitt b-b der Figur 2;

die Figur 5

einen einzelnen Einlege-Siebrahmen;

die Figur 6

einen Schnitt c-c der Figur 5, wobei mehrere Einlege-Siebrahmen gestapelt sind;

die Figur 7

einen Stapel von Siebkasten mit Auflegebewegung des obersten Einlege-Siebrahmens;

die Figur 8

ein Grossplansichter mit eingebautem Siebstapel;

die Figur 9

zeigt einen Siebreiniger mit Bumerang-Form im Grundriss;

die Figur 9a

eine Ansicht gemäss Pfeil a;

die Figur 9b

eine Seitenansicht gemäss Pfeil b und

die Figur 9c

den selben Siebrreiniger im Einsatz bei der Schlitzreinigung;

die Figur 10

zeigt einen 3-armigen Siebreiniger im Grundriss;

die Figur 10a

den 3-armigen Siebreiniger bei der Schlitzreinigung;

die Figur 10b

einen Schnitt J-J der Figur 10;

die Figur 10c

einen Schnitt H-H der Figur 10;

die Figur 11

zeigt einen 4-armigen Siebreiniger im Grundriss in einer Eckreinigungsposition;

der Figur 11a

in einer Reinigungsposition im Schlitzsowie am Siebgewebe; und

die Figur 11b

in Siebreinigungsposition.

Show it:

the figure 1

a sieve frame in a laying motion on a sieve box;

the figure 2

a floor plan of a sieve box with an inserted sieve frame, partly without sieve fabric;

the figure 3

a section aa of Figure 2;

the figure 4

a section bb of Figure 2;

the figure 5

a single insert screen frame;

the figure 6

a section cc of Figure 5, wherein a plurality of insert screen frames are stacked;

the figure 7

a stack of sieve box with laying movement of the top insertion sieve frame;

the figure 8

a large plan sifter with built-in sieve stack;

the figure 9

shows a sieve cleaner with boomerang shape in the floor plan;

the figure 9a

a view according to arrow a;

the figure 9b

a side view according to arrow b and

the figure 9c

the same screen cleaner used for slot cleaning;

the figure 10

shows a 3-arm screen cleaner in the floor plan;

the figure 10a

the 3-arm screen cleaner for slot cleaning;

the figure 10b

a section JJ of Figure 10;

the figure 10c

a section HH of Figure 10;

the figure 11

shows a 4-arm screen cleaner in the floor plan in a corner cleaning position;

of Figure 11a

in a cleaning position in the slit and on the screen fabric; and

the figure 11b

in screen cleaning position.

Ways of Carrying Out the Invention

In the following, reference is now made to FIGS. 1-4. A sieve box 1 has a plurality of discharge channels, two discharge channels for the sieve repulsion or for the coarse material, 2A and 2A 'and a discharge channel 2F for the sieve diarrhea or the fine material.

A screen frame 3 is drawn in Figure 1 in a slightly inclined position and represents a laying movement of the Sieve frame 3 on the sieve box 1. The inner surface of the sieve box 1, below the sieve frame, is closed with a flat base plate 4, so that the fine material or the sieve diarrhea can only be cleared from the base plate 4 through lateral slot openings 5 (FIG 3). Sieve cleaners 6 and 6 'are placed on the base plate 4 before the sieve frame 3 is inserted. The screen cleaners 6 and 6 'have a double function, with a scraper foot 7 the screen diarrhea on the flat base plate 4 is to be cleared out. According to the example in FIGS. 1-4, the fine material is only discharged via the discharge channel 2F, so that the fine material must be moved in a corresponding longitudinal direction arrow 9 over the entire length of the floor against the slot openings 5. The sieve box 1 has web strips 12 'directly above the floor, which divide the surface of the base plate 4 into three longitudinal fields. These web strips 12 'serve primarily to increase the stability of the base plate 4. The sieve frame 3 also has base strips 12 which are arranged exactly above the base strips 12 of the base plate. The sieve frames additionally have transverse web strips 13. This results in the example of FIGS. 1-4 not only clearing fields B, D and F, as would result from the web strips 12 'of the base plate 4, but also by the additional subdivision of the sieve frame 3 with the cross bars 13 additional clearing fields A, C and E. The number of clearing fields (A ... F) is thus determined by the corresponding subdivisions of the insert sieve frame. It is now crucial that a cleaning element 6 is inserted into each of the common clearing fields formed in this way, which combines, keeps the screen fabric free at the top and clears the bottom at the bottom.

Figures 3 and 4 each show a section of Figure 2, two screen boxes 1 are placed on top of each other. A sieve frame 3 is inserted in each of the sieve boxes 1, so that a free product fall-through and discharge space 11 is formed between the sieve cloth 10 and the base plate 4, in which the sieve cleaners 6, 6 'etc. can move freely. The scraper foot 7 of the cleaning elements 6, 6 'also has the function here of moving the fine material from the cleaning field B to A or. D to C resp. F to promote E, which is easily possible because the cross bars 13 are arranged only on the sieve frame 3 and not on the base plate, so that a slot 5 'is formed at the corresponding location above the base plate. With knobs or brushes protruding upwards, the screen fabric 10 is continuously cleaned cleanly over the entire screen area. The sieve cleaner has a wobble foot 14 in its central area, so that the sieve cleaner alternately fulfills the corresponding function by slight tilting movements upwards and downwards, and apart from frictional and inertial forces, can move freely over the flat base plate 4.

A multi-armed configuration of the cleaning elements 6, 6 'has the great advantage that each surface part of the screen fabric is kept clean up to the outermost corners, just like the bottom plate. The cleaning elements ensure an optimal cleaning effect in all room directions. The relatively large mass of the screen cleaner and also the low-friction base plate support a very intensive movement of the screen cleaners 6, 6 '. Even during long periods of operation, the cleaner is particularly able to keep the screen mesh and the base plate clean.

FIG. 5 shows an almost ideal square space or cleaning area division with 9 areas, the screen fabric 10 being shown only over half the screen frame 3. The length of a cleaning field is denoted by Län and the width by Bre. Considerable forces are applied to the fabric. Another key point of the new invention is that the sieve frames are made from thin and light metal strips, which relates in particular to the frame profiles 13, 13 'and 14. As can also be seen from FIG. 6, the screen frames 3 have a covering on one side only, namely the screen fabric covering. On the opposite side, the sieve frame is open, so that the sieve fabric 10 is now equally freely accessible and easy to clean on both sides for the first time when inserting or replacing sieve frames. The entire lightweight metal frame can be produced in one piece using a metal die-casting process or, preferably, as a welded construction. It is very important that the frame allows a very minimal deflection in the elastic range, due to the tensile forces from the screen covering, which supports the maintenance of the tension in the screen fabric during operation. The deflection is symbolically indicated by line 15 (Figure 5). For a screen change, a larger number of reserve screen frames 3 with different coverings must be kept ready. The fact that the sieve frames have sufficient inherent rigidity with very thin frame profiles and only about half the thickness D compared to the known sieve frames means that they require little space for replacement storage, as can be seen from FIG. 6. However, the web strips 12, 12 'are expediently also produced from a corresponding metal profile, which can be a solid or hollow profile. The use of an all-metal frame has proven to be particularly advantageous. Such a frame points a high degree of bending stiffness if an appropriate elasticity value is preferably selected. The screen frame can also be designed as a metal, wood or metal-plastic composite.

FIG. 7 shows a stack 16 of 8 sieve boxes 1 stacked one on top of the other, 3-arm sieve cleaners being inserted.

FIG. 8 shows an entire square plan sifter, the door 18 for a sieve compartment being removed and an entire sieve stack 16 being visible. The sieve stack 16 has a sieve box 1 in a known square plan sifter 24. With the sieve box according to the invention, the number of sieve boxes and sieve frames can be increased by at least 10% while maintaining the spaces for product conveyance above the sieve and the same height of the plan sifter housing. The entire plan sifter 17 has a swing drive, not shown, which forces all screens to have a circular movement, for which purpose the plan sifter 17 is suspended on bars 19 as a cantilever. The goods are fed to the sieve stacks via inlet connectors 20, 20 'etc. and the sorted goods are discharged via discharge connectors 21, 21' etc.

9, 9a and 9c, a cleaning element is designed as a boomerang 30, with two typical, angled cleaning arms 31, respectively. 31 '. The two arms are provided with knobs 32, which have the function of screen fabric cleaning. The boomerang 30 is provided in the vertical axis of gravity S with a wobble foot 14 which is a dimension "X" of a few millimeters compared to the two support feet 33 and. 33 'protrudes. Furthermore, the boomerang 30 opposite to the two arms 31, respectively. 31 'has a bottom and slot broaching nose 34 which projects so far that the corresponding part can push the fine material through the slot 5, as is shown in FIG. 9c. So that the necessary impacts from the side parts 35, for example the sieve frame 3, also occur during the slot cleaning, the boomerang 30 has a butt plate 36 in the direction of the bottom and slot clearing nose 34. For the proper functioning of the cleaning element, it is very advantageous if only the wobble foot 14 protrudes, but the support feet 33, 33 'and the lower floor clearing edge 37 of the slot and floor clearing nose 34 are at the same height. This creates a free interplay between the operational elements, and it results statistically, with very high accuracy, corresponding to approximately the same number of work assignments. In FIG. 9c, the knobs 32 are simultaneously in use for cleaning the screen cloth 1 and the bottom and slot clearing nose 34 for cleaning the slot 5.

FIG. 10 shows a 3-star 40 in which three arms 41, 41 'and 41' 'are offset by 120 ° to one another. To protect the screen fabric cleaning agent, for example for the knobs 32, each of the arms is designed on the outside as a baffle head 42, which is the actual abutment part for the screen cleaner. As can be seen from the two sectional drawings H-H and J-J, the arms 41, 41 'and 41' 'each have a roof-like shape in cross section. The two arms 41, 41 'are of identical design, but the arm 41' 'additionally has a bottom and slot clearing nose 34.

Figures 11-11b show a 4-star 50. The arms 51 and 51 'are identical, the arm 51''is similar, but has a cleaning rib 52 instead of the cleaning knobs. Analogous to the 3-star 40, the arm 51 '''additionally has a bottom and slot clearing nose 34. In FIG. 11a the knobs 32 are used for the Cleaning the screen fabric, whereas in FIG. 11b bristles, which are embedded in the arm 51 ''', clean the screen fabric 10. FIG. 11 shows the 4-star cleaner 50 in the phase of cleaning a corner of the sieve box base 4. A pile of goods 53 is pushed directly into the slot opening 5 according to arrow BG by the relative movement B - S between the 4-star Cleaner 50 and the plan safe or the floor 4 according to arrow BP. It is possible to build cleaning elements with even more arms, but these no longer have any advantages in terms of cleaning intensity.

Claims (8)

1. Apparatus for plansifters, consisting of a plansifter sieve which comprises a sieve box (1) with floor plate (4) and fine-material discharge, a sieve frame (3) and freely movable cleaning elements, the sieve frame (3) being provided with a cover at one side only and having preferably at least in one direction bridge strip (12) subdividers for forming a corresponding number of cleaning areas in sieve (3) and floor plate (4), cleaning elements being insertable in the cleaning areas to lie on the floor plate (4), characterised in that the sieve frame (3) is constructed without connecting elements and in the form of a sieve box (1) with a floor plate (4), into which the sieve frame (3) is insertable in shape-locking manner, this insertable sieve frame (3) having an inherent rigidity sufficient to accept without screwing connections or the like, without substantial deformation of the insertable sieve frame (3) the forces which occur due to the sieve having a cover at only one side.
2. Apparatus according to claim 1, characterised in that the sieve box (1) and the sieve frame (3) have coinciding bridge strip (12) subdividers, for discharge of fine product at two sides.
3. Apparatus according to claim 1 or 2, characterised in that the sieve frame (3) has additionally transverse subdividers, to form a plurality of cleaning areas, and a corresponding number of cleaning elements, and preferably a plurality of cleaning areas of preferably approximately square shape are formed.
4. Apparatus according to one of claims 1 to 3, characterised in that the sieve frame (3) has the smallest possible height measurement, and is constructed as a freely interchangeable insertable frame.
5. Apparatus according to one of claims 1 to 4, characterised in that the sieve frame (3) is constructed as a metal frame, preferably as an all-metal frame.
6. Apparatus according to one of claims 1 to 5, characterised in that the sieve box (1) is made of wood and forms an external frame, with 1 to 3 channels, and the product-contacted surfaces are coated preferably with synthetic plastic material and the floor plate (4) of the sieve box (1) is made of metal or synthetic plastic material.
7. Apparatus according to one of claims 1 to 6, characterised in that the sieve frame (3) with the sieve cloth (10) finishes flush with the top of the sieve box (1).
8. Apparatus according to one of claims 1 to 7, characterised in that the sieve frames with a sieve cloth covering each of them are interchangeable in relation to the sieve box, the sieve frames being constructed without supporting grids for the purpose of reducing the sound energy from source noise.

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