EP0015633A1 - Method and apparatus for grading grains or seeds - Google Patents

Abstract

Process and plant for sorting grain or seed material such as coffee beans. The main problem when sorting such materials, lies in the shape of the grains which is far from being round, resulting in the grains going through the meshes of a sieve also depending on their position relative to the sieve. During the first stage of the process disclosed, foreign materials are removed from the material to be sorted which is then sorted in a moving sieve (15, 16) preferably linear. The vibrating motion, in relation with barrier baffle, provides a spreading of the material on the surface of the sieve and forces the grain to move along the longitudinal axis thereof. Thus, the probability for the grains to traverse the meshes of the sieve by their smaller cross section is increased. The efficiency of the screening operation is thereby increased. The installation comprises on the top of sieve (15, 16) barrier baffles (21) transversal to the motion of the material, and preferably made of elastic material such as rigid rubber.

Description

Technical field

The invention relates to a method for classifying grain or seeds, such as for classifying cereal grains, seeds, legumes, rice grains, corn kernels, coffee beans or the like. The invention also relates to a classifying device which is preferably suitable for carrying out the method according to the invention.

Underlying state of the art

For the extraction of grain or seeds, seeds or similar. it is necessary to separate the goods to be classified into individual classes in terms of quality, size and shape. It is known to use sieves for this, the main purpose of the sieving being to separate the classified material into different size classes. However, it is also known that form factors of the grains to be sieved cannot be taken into account sufficiently with a flat sieve. For example, a kernel of corn, especially the so-called "tooth corn", has a very peculiar, large, elongated shape that is pointed towards one side. The ratio of the largest cross section to the smallest cross section can easily be between 2 and 6. If you apply a product of such a special shape to a sieve, the sieving takes place more randomly, ie the classification is subject to statistical laws. Depending on the position in which the grain comes to lie relative to the screen perforation, it can fall through the perforation or not.

The situation is similar with other grains, such as rice, oats, etc. With rice, it is a goal of seed production to separate grains that still have the outer shell from those that are peeled. In the case of maize, the maize kernels have to be divided into size classes that allow only very slight deviations. The reason for this is that maize is sown as a single grain when sowing and the grains are individually placed and released in special drums. If the deviations between the grains are too large, two smaller grains are very often fed into a compartment of the drum, which can give rise to faults.

In the case of other types of grain, the size of the grain is a quality criterion and as such must be adhered to within the narrowest possible limits.

However, the elongated shape of such grains must not have a negative impact on the size classification, which almost precludes the use of flat sieves and can lead to correspondingly low yields. In practice, a somewhat larger spread of grain sizes has been accepted up to now. Thus, the opinion was also held that the special classification task for classification goods, in which the shape of the individual part differs significantly from the round shape or in which shape deviations also represent a classification criterion, can be solved more advantageously with a rotating sieve drum. A sieve drum, which uses both the rotation effect (shifting effect) and vibration forces, is complicated and also very susceptible to failure.

In the previously known classification technology, however, it has been shown that, in particular, the problem of swimming down and unrolling the classified material was not always given the necessary attention. In particular, maize, rice and coffee beans tend to swim, whereby due to the center of gravity the grain with larger dimensions in the length and / or width of a single grain comes to lie horizontally on the sieve: in this position the grain then swims with its largest projecting area over the small sieve holes.

When classifying round soybeans, a comparatively small layer thickness of the material above the sieve had previously been sought. A large sieving capacity then means a correspondingly quick movement of the material over the sieve. However, the soybean begins to roll and tends to roll over the individual sieve holes. These effects are exacerbated by changing loads and vibration of the screen.

The use of known classifying devices was also mostly limited to the classification of only a small number of different items to be classified, since the individual device was adapted to the different requirements of the individual item in the interest of a high discharge yield.

Disclosure of the invention

Starting from the above, the object of the invention is to find a classification method in which the classification is improved in size and the negative influence of form factors is eliminated as far as possible. In particular, however, a method is to be found which, particularly in the case of such classification products, still allows the use of flat sieves otherwise the desired classification accuracy could not be achieved. The method according to the invention should meet the highest demands both in terms of its performance and in its classification accuracy, without the need for complicated additional expenditure.

Furthermore, the invention is intended to find a device for carrying out such a method according to the invention which is suitable for use with a large number of very different classifying goods (such as cereals, legumes, soybeans, coffee beans, seeds or the like) and with which a particularly good classification is achieved what is particularly important in the production of seeds, on which a substantial part of the progress possible in agricultural production is based.

According to the invention, this object is achieved in a method for classifying grain or seeds in that the classifying material is cleaned of foreign matter in a first stage and classified by a (preferably linear) moving sieve surface with multiple stowage.

The method according to the invention has surprisingly achieved great success in practice. The principle previously represented in the specialist world that the sieving capacity is at a maximum at a relatively low dumping height and decreases with increasing dumping height is completely broken through in the invention by deliberately requiring repeated jam there. When using the method according to the invention, it was surprisingly found that _' for sieving out-of-round grains not only the passage through the sieve opening alone may be considered, but also the preparation, ie the correct positioning of the grains relative to the sieve holes. In view of this, a Targeted grain movement in the grain layer, especially against the general flow direction of the material, achieved, which results in a surprisingly good sieving effect. In this way, the individual grains are literally "set up" and can thus fall through the perforated screen with their smallest cross-sectional area. Grains that come into contact with the screen perforation, for example, at a slight incline, are literally set up by the grain layer above and guided into the opening with a slight pressure. The product stowage also has the particular advantage that the product is repeatedly forced to recirculate. This means that a grain is given more than once in each barrage to take a favorable position for passage through the perforated screen.

In an advantageous embodiment of the method according to the invention, the classified material is accumulated several times, preferably to a height of 2 to 5 cm, and the product is transported from dam stage to dam stage in an area directly above the screen surface (the specified height dimensions being particularly advantageous for processing purposes) of rice; in the case of corn, it is advisable to thaw even more than 5 cm high).

A further advantageous embodiment of the method according to the invention is that each dam stage is formed by a dam member directed at the product flow at low pressure and the size of the passage cross section is regulated as a function of the product flow, preferably by the product flow itself. The deflection of the dam member can be connected with a progressively growing force. The passage cross-section usually has a size corresponding to one to three times the thickness of a single grain point or swing around such a value; if more product is being conveyed at the moment, the passage cross-section should be able to adapt by opening it accordingly.

The device according to the invention is based on a classifying device with a flat sieve which can be set into (preferably linear) vibrations, wherein according to the invention, damming members are arranged above the sieve and transversely to the longitudinal direction of the sieve. Such a device according to the invention makes it possible to carry out the method according to the invention and to achieve the advantages associated with it.

• Besonders gute Ergebnisse lassen sich beim Klassieren erzielen, wenn in Sieblängsrichtung vorzugsweise drei oder auch mehr Stauglieder angeordnet sind. Es hat sich gezeigt, daß der Einsatz von bis zu sechs Staugliedern pro Meter Sieblänge eine effektive Steigerung der Siebqualität ermöglicht. Bei besonderen Klassierprodukten kann auch eine noch größere Anzahl von Staugliedern wünschenswert sein.

The device according to the invention can advantageously be further developed in various ways:

• Particularly good results can be achieved in the classification if three or more dam members are preferably arranged in the longitudinal direction of the sieve. It has been shown that the use of up to six damming elements per meter of screen length enables an effective increase in the screen quality. In the case of special classification products, an even larger number of jam members may be desirable.

For the classifying function, it is also advantageous if the sieve is divided into at least two compartments in the longitudinal direction and each compartment has dam members.

A particularly simple but effective design for the dam members can be achieved in a classifying device according to the invention in that the dam members are suspended in the manner of a hanging swing door which can be opened by the product flow in the direction of product flow.

It is also advantageous if the inclination of the damming members and / or their distance from the screen surface can be adjusted in a classifying device according to the invention. It is particularly advantageous if the dam members in the sieve box are adjustable from the outside and for this purpose the sieve box is at least partially made of transparent material, preferably transparent plastic, such as e.g. Plexiglas, is carried out, which means that the classification quality can also be checked during operation. It is also advantageous to design the inclination of the sieve and the vibration intensity to be adaptable to the respective application. The invention enables a particularly effective use of the sieve inclination setting because the product cannot simply swim away as a repulsion in the case of a larger inclined position.

Another advantageous embodiment of the classifying device according to the invention also consists in that the dam members are designed as pendulum flaps hanging down on hinges and deflectable in the product flow direction from the product flow, whereby a simple but effective self-regulation of the passage cross section can be achieved depending on the strength of the product flow .

It is also advantageous if the dam members are made of solid rubber, plastic or fabric. The use of congestion links made of rubber of medium softness has proven particularly good. In the invention, the dam members have a function which corresponds to that of a "curtain", as has been used occasionally in the past (but only to hold back spray particles). However, the retention force of the dam member should always be so great that a product in all operating cases stowage is guaranteed, the height of the product stowage should advantageously be approximately approximately twice as large or even greater than the corresponding layer height in the previously known normal screening technique.

The use of the method according to the invention for classifying soybeans, which have an almost spherical shape, led to considerably improved classification results than was possible with previously known methods. Even in the case of classifying coffee. beans (the classification of which is largely determined by the size of the beans), a very economical classification of the individual coffee qualities could be achieved when using the method according to the invention or the device according to the invention.

Brief description of the drawings

• Figur 1 eine diagrammatische Darstellung des erfindungsgemäßen Klassierverfahrens;
• Figur 2 eine erfindungsgemäße Klassiervorrichtung;
• Figur 3 ein einzelnes Sieb zum Einsatz bei einer erfindungsgemäßen Klassiervorrichtung, das mit fünf Staugliedern versehen ist;
• Figur 4 eine Darstellung der Anordnung der Stauglieder und der Längsleisten;
• Figur 5 bauliche Einzelheiten eines Staugliedes;
• Figur 6 eine prinzipielle Strömungsdarstellung des Produktstromes bei einem erfindungsgemäßen Verfahren bzw. einer erfindungsgemäßen Vorrichtung;
• Figur 7 eine Prinzipdarstellung der Funktionsweise im Bereich einer einzelnen Siebzone;
• Figur 8 eine andere Ausführungsform für ein Stauglied.

The invention is explained in more detail in principle by way of example with reference to the drawings. Show it:

• FIG. 1 shows a diagrammatic representation of the classification method according to the invention;
• Figure 2 shows a classifying device according to the invention;
• Figure 3 shows a single screen for use in a classifying device according to the invention, which is provided with five dam members;
• Figure 4 is an illustration of the arrangement of the damming members and the longitudinal strips;
• FIG. 5 structural details of a dam member;
• Figure 6 is a basic flow diagram of the Product flow in a method according to the invention or a device according to the invention;
• FIG. 7 shows a basic illustration of the mode of operation in the region of an individual screening zone;
• Figure 8 shows another embodiment for a dam member.

Detailed description of the drawings

In principle, the method according to the invention is shown in FIG. 1, in which, in a manner known per se, the product to be classified is first cleaned in a stage 1 and then in the actual classification stage 2 into the desired size classes. In this way, the classifying screen is not burdened from the outset by undesirable additives. The classifying screen has several outputs.

FIG. 2 shows a screening device 4 with two parallel runs 5 and 6, which are separated by an intermediate floor 7. The inclination (a) of the sieve device 4 as a whole is adjustable. Correspondingly, the scheme parts 8 and 9 are arranged in the head part 10 of the screening device 4 and the necessary scheme parts 12 in the foot part 11 of the screening device. The flow of the classified material, e.g. a grain flow or a flow of coffee beans is 10-fed into the sieving device 4 via the inlets 13 and 14 of the head part.

The diarrhea of the sieves 15 and 16 is passed on via an outlet 17 and 19, and the repulsion of the sieves 15 and 16 in each case via an outlet 18 and 20. The sieve device 4 has dam members 21 which divide the entire sieve zone or the corresponding process zone into several units.

A vibrator, symbolically represented in FIG. 2 as an electromagnet, causes the sieve device 4 to vibrate. Instead of the electromagnet, unbalance vibrators can also be used in practice, the inclination (.beta.) Of which can be adjusted and which, by suitable attachment, can produce a, preferably linear, oscillating movement.

Figure 3 shows a single screen 30 which is provided with five dam members 21. The sieve bottom 30 consists of a sieve 31 and a wire mesh 32, both of which form a cavity 33 in which there are balls 34 for the continuous cleaning of the sieve 30.

FIG. 4 shows the combination of the dam members 21: two wooden strips 40 separate the entire sieve zone into three longitudinal channels as longitudinal strips and are fastened to a sieve 43 with screws 42.

Figure 5 shows the representation of a dam member. Screws 51 are attached in the wooden strip 50 and fastened by means of nuts 52. The actual dam member 53 is connected to the screw 51 via an angle iron 54. The angle iron 54 is fixed by nuts 55 and 56. Depending on the product and the quantity of product flowing through, that is, on the desired hourly output, the angle iron 54 and thus the dam member 53 can be adjusted in its height 57 (relative to the sieve). The dam member 53 is advantageously made of materials such as rubber, plastic, reinforced or rigid fabrics and - in special cases - also of sheet metal. It is essential that the damming element 53 opposes the product flow with a resistance, through which it can cause a certain damming effect. Possibly. a single dam member 53 on a sieve surface can lead to a significant improvement in the classification. If elastic dam members, eg made of rubber, are used, the distance between the dam member and the sieve surface (X) is set automatically.

FIG. 6 shows a schematic representation of the sequence of movements of the flow of the classified material. The entire screening zone is divided into a number of individual processing zones 60 by the various damming members. The main product flow along the screen is overlaid by a backward flow in the individual process zones.

• Das Stauglied 61 staut dabei den Produktstrom, wobei die einzelnen Körner eine senkrechte Bewegung nach oben ausführen und dann aufgrund der (linearen) Schwingung des Siebkastens rückwärts entsprechend der Richtung des Pfeiles 62 bewegt werden. Zum besseren Verständnis sind in Figur 7 nur links vom Stauglied 61 Körner dargestellt, rechts hingegen nur ein Siebboden ohne Körner (obwohl dort im praktischen Verfahren selbstverständlich Körner vorliegen). Die Längsrichtung ist dabei durch den Pfeil L dargestellt.

Figure 7 shows the operation of a single sieve. Zone: .

• The damming member 61 jams the product flow, the individual grains performing a vertical movement upwards and then being moved backwards in accordance with the direction of the arrow 62 due to the (linear) vibration of the sieve box. For a better understanding, 61 grains are shown in FIG. 7 only to the left of the damming element, on the other hand only one sieve plate without grains (although there are grains in the practical process, of course). The longitudinal direction is shown by the arrow L.

FIG. 8 shows a further embodiment for a dam member, which here is in the form of a brush 65, preferably made of plastic, which is attached above the sieve bottom 67.

• Das Produkt wird über den Einlauf in die Siebvorrichtung 4 eingegeben. Durch die Stauglieder wird die ganze Siebzone in mehrere einzelne Einheiten unterteilt, wobei Figur 7 sehr anschaulich die Funktionsweise innerhalb einer einzelnen Einheit zeigt. Der Produktfluß wird über die Stauglieder gestaut, wodurch sich die einzelnen Körner senkrecht nach oben bewegen; dabei werden sie durch die Vorwärtsbewegung einer untersten Kornlage einerseits und die Linearbewegung der Siebvorrichtung 4 andererseits wieder rückwärts befördert (vgl. Figur 7). Die sich aufstauenden Körner hemmen die unterste Kornlage in der Vorwärtsbewegung, wodurch ein überrolleffekt entsteht. Die Körner der untersten Kornlage werden regelmäßig in eine senkrechte Lage gebracht und fallen über ihren kleinsten Querschnitt durch die Sieblochung hindurch nach unten.

The functioning of the device according to the invention is as follows:

• The product is fed into the screening device 4 via the inlet. The dam members divide the entire sieve zone into several individual units, FIG. 7 very clearly showing the mode of operation within a single unit. The product flow will jammed over the jam members, causing the individual grains to move vertically upwards; they are conveyed backwards by the forward movement of a lowermost grain layer on the one hand and the linear movement of the screening device 4 on the other hand (cf. FIG. 7). The accumulating grains inhibit the lowest grain position in the forward movement, which creates a rollover effect. The grains of the lowest grain layer are regularly brought into a vertical position and fall down over their smallest cross-section through the perforated sieve.

A side wall of the screening device is preferably formed from plexiglass. Since the height of the separating elements, for example according to the embodiment according to FIG. 5, can be adjusted, an adjustment can be made both on the basis of the observation by the operator and on the basis of the sieving performance until the desired grain movement is optimal in the individual sieving zones, i.e. until the highest classification performance occurs.

The dam members can also be easily replaced. This makes it possible to adapt the retention force of the dam members to the flow properties of the product or to optimally classify different products. The use of up to six damming elements per meter of screen length has proven to be particularly advantageous.

Claims (12)

1. A method for classifying grain or seeds, characterized in that the classifying material is cleaned in a first stage of foreign matter and classified by a (preferably linear) moving sieve surface (15, 16; 31; 43) under multiple stowage. 2. The method according to claim 1, characterized in that the goods to be classified are jammed several times, preferably to a height of 2 to 5 cm, and the product is transported from the weir to the weir in an area directly above the screen surface (15, 16; 31, 32; 43 ) is made. -3. Method according to claim 2, characterized in that each dam stage is formed by a dam member (21; 53; 61; 65) which is directed against the product flow at low pressure and the size (x) of the passage cross section is regulated as a function of the product flow. 4. Classifying device with a flat sieve '(15, 16; 31, 32; 43; 67) which can be set into (preferably linear) vibrations, in particular for carrying out a method according to claim 1, characterized in that above the sieve (15 , 16; 31, 32; 43; 67) and dam members (21; 53; 61; 65) are arranged transversely to the longitudinal direction of the screen. 5. Classifying device according to claim 4, characterized in that a plurality, preferably at least three, damming members (21; 53; 61; 65) are arranged in the longitudinal direction of the screen. 6. Classifying device according to claim 4 or 5, characterized in that the dam members (53) are designed in the manner of a hanging swing door which can be opened in the product flow direction by the product flow. 7. Classifying device according to claim 4 or 5, characterized in that the screen is divided in the longitudinal direction into at least two compartments (5, 6) and each compartment has dam members (21). 8. Classifying device according to claim 4 or 5, characterized in that the inclination of the damming members (21; 53; 61; 65) and / or their distance (57) from the screen surface (15, 16; 31,32; 43; 67) is adjustable. 9. Classifying device according to claim 4 or 5, characterized in that the dam members (53) in the sieve box are adjustable from the outside and the sieve box for controlling the setting of the separating elements (53) is at least partially made of transparent material. 10. Classifying device according to claim 4, characterized in that the damming members (21) are designed as pendulum flaps (53) which hang down on hinges and can be deflected by the product flow in the product flow direction (x). 11. Classifying device according to claim 4 or 10, characterized in that the dam members (21; 53; 61) consist of rubber, plastic or reinforced material. 12. Classifying device according to claim 4, characterized in that the damming members (21, 53, 61, 65) are formed as a fixed baffle strip made of elastic material.

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