RU2263540C2 - Roll-type mill for grinding and sorting of bulk materials - Google Patents

Abstract

FIELD: equipment for grinding and sorting of bulk materials.

SUBSTANCE: roll-type mill has at least one pair of rolls rotating in opposite directions and having gap therebetween for passage of material to be ground, and sieving device united with rolls for separating ground products in accordance with sizes of ground material particles. Sieving device has sieving surface arranged below rolls in such a manner that material ground by means of rolls falls immediately thereon by gravity.

EFFECT: increased efficiency in grinding and sorting of bulk material.

11 cl, 3 dwg

Description

The present invention relates to a roller mill for grinding bulk materials, in particular grain, in accordance with the restrictive part of the independent claim 1 of the claims.

In the field of crushing technology, which mainly, but not exclusively, relates to the present invention, it is known to use mills that have one or more pairs of rollers rotating in opposite directions, set at a predetermined distance from each other, so that between their respective cylindrical surfaces formed a gap for the passage of the material to be crushed.

In these mills, usually several consecutive cascades of grain grinding are provided until the flour is ground, milled to the desired degree of grinding. In this case, between any two successive grinding cascades, a cascade is provided in which sorting and separation of grinding products into smaller and larger fractions is carried out, so that the products separated in this way are sent to subsequent grinding stages in accordance with the particle sizes of the milled material.

A grinding mill that has the above characteristics is described in US Pat. No. 1,497,108.

From European patent application N949003 there is known a mill for grinding grain, which comprises two separate crushing passages arranged successively one after another with respective rollers rotating in opposite directions and a screening device inserted between the passages. The screening device includes a rotating member that acts on the product exiting the first crushing pass, so that it is forced to the screening surface to separate a substantial amount of the product before reaching the second crushing pass. In the roller mill described in the said document, it is further provided that the product passing through the screening surface and the product leaving the second crushing pass are sequentially combined and sent to a separation and sorting unit, for example, to a sieving unit.

As regards this latter characteristic, the known mills comprise conveyor devices for transporting material milled by rollers into a special screening device. For example, it is known that grinding products can be directed and lifted to the inlets of separators having one or more sieves with cells of different sizes, located one above the other, so that as the product falls on top of it, it is divided into fractions having uniform sizes .

This type of construction, in which it is necessary to provide conveyors and lifting devices between the rollers and the separator for each grinding stage, has a large weight and is structurally quite complex. Moreover, since conveyors allow localized and concentrated unloading of material on the separator sieves, a constant and uniform distribution of material on the sieve cannot be guaranteed, which leads to the need to use a sieving surface of a larger area to eliminate the risk of excessive or intermittent material intake and a corresponding reduction efficiency and output performance.

The technical task of the present invention is the creation of a roller mill for grinding bulk materials, in particular grain, which allows structurally and functionally eliminate the disadvantages of the previously known devices.

This problem is solved in accordance with the present invention by creating a roller mill, made in accordance with the attached claims.

The foregoing and other features and advantages of the invention will be more apparent from the following detailed description, given by way of example, not limiting, and given with reference to the accompanying drawings.

Figure 1 shows a perspective view in partial section of a roller mill in accordance with the present invention.

Figure 2 shows a side view in partial section of the mill of figure 1.

Figure 3 shows a perspective view in accordance with figure 1.

Figure 1 shows a roller mill 1 for grinding grain, such as corn, wheat and the like, made in accordance with the present invention.

The mill 1 has one or more pairs of rollers 2 rotating in opposite directions, between which a gap 3 is formed for the passage of the material to be crushed, as well as a feeding device, generally indicated by 4, located above the rollers 2 and including a vibration hopper 5 for storing the material to be crushed, as well as for feeding and directing it into the gap 3 by means of deflecting elements 6.

The rollers 2 are mounted rotatably on the mill frame 7 and are located inside the housing 8, which below the rollers has walls 8a installed with an inclination, converging at the outlet 8b, which is aligned vertically with the gap 3.

Elements in the form of drawers 9, located between the rollers 2 and the outlet 8b, are mounted with the possibility of movement relative to the housing 8 and are used to take samples of ground material from the exit of the rollers.

The mill 1 also contains a screening device, generally indicated by 10 and mounted under the rollers 2 on the frame 11. The device 10 is provided with a first chamber 12, which communicates with the outlet 8b, and a second chamber 13, which is separated from the chamber 12 and communicates with it using a perforated screening surface 14A sieve 14.

The sieve 14 has a mainly semi-cylindrical frame 14b, which is parallel to the longitudinal axis of the rollers and has a length mainly corresponding to the axial length of the rollers. Such a technical solution is preferable, however, the sieve may have an orientation and axial dimension that differ from similar parameters of the rollers.

The frame 14b is detachably secured to the frame 11, and a mesh or sieve fabric with twisted threads is stretched over it to form a perforated screening surface 14a of the sieve.

A mixing means is also provided in the first chamber 12, which comprises a rotor 15 with radial blades 16, the axis of rotation of which is predominantly parallel to the axes of rotation of the rollers 2 and is offset from the vertical plane tangent to the rollers in the region of the gap 3.

Each blade 16 has a plurality of elongation 16a protruding radially from the rotor 15 in the form of a comb. The location of the rotor 15 inside the chamber 12 is chosen so that the free ends of the blades during their circular motion pass close to the perforated surface of the sieve 14. The brushes 17, which are located on the free ends of the blades 16, form a means of cleaning the surface of the sieve.

On the side opposite from the sieve 14, the chamber 12 has a polygonal profile configuration formed by a pair of inclined deflectors 18, 19, the second of which also forms a means of directing the flow of ground material entering the chamber 12 through the outlet 8b.

With regard to this point, it should be noted that with the help of the deflector 19, the milled material is guided in such a way that it falls under the action of gravity on the screening surface 14a, along a path that is oriented mainly tangentially to the surface (Fig. 2).

The chamber 12 also communicates with the end of the pipe 20 through an opening 21 through which material rejected by the sieve 14 is discharged, as will be explained in more detail in the following description. The opposite end of the pipe 20 is connected to the conveyor means 22, for example, with a vertical screw conveyor provided for lifting the milled material rejected by a sieve up into the hopper 5.

The second chamber 13 has side walls 13a that are inclined so that they converge at the outlet 23, under which there is a horizontal conveyor 24, for example, of a screw type. The conveyor 24 is designed to move the milled material into the pneumatic conveyor 25, which, in turn, is designed to move the material to the subsequent processing stages in accordance with the pre-selected grinding model.

In addition to the functions described above, the rotor 15 with radial blades serves, as a result of its rotation, to create an air intake through one or more inlets located in the upper part of the housing 8, which are formed, for example, using perforated sections 8c of the housing. The intake air is discharged through one or more outlets 13b located at the side walls 13a of the chamber 13, as well as at the outlet of the conveyor 24 in the inlet region of the pneumatic conveyor 25.

Due to the intake of air, which is discharged in the exit region of the conveyor 24 and the side walls of the chamber 13, air circulation is also created, the function of which will be more clear from the following description, moreover, the air is sucked through both rollers 2 and through the first and second chambers 12, 13 while air circulation occurs through the above-mentioned inlets (air intakes). In figure 3, the direction of flow of forced air circulation is shown schematically by arrow A.

When the device is operating, the material ground by rollers 2 falls into the chamber 12 of the screening device by gravity and is separated by a sieve 14. The separated material falls into the chamber 13, where it passes through the outlet 23, accumulates on the conveyor 24 and moves to the inlet of the pneumatic conveyor 25, which moves the material for further processing, while the material rejected by the sieve 14 is moved into the pipe 20 by means of a rotor with vanes 15, for subsequent lifting into the hopper 5 using a vertical con EIER 22 and to additional grinding using a pair of rollers on the next pass. It should be borne in mind that the movement of the rejected material into the pipe 20 is facilitated by deflectors 18, 19 located in the upper part of the chamber 12. When the rotor 15 is rotated, the brushes 17 made at the ends of the blades 16 clean the perforated sieve surface 14a, which facilitates the separation of the ground material that continuously falls into the chamber 12 under the action of gravity. Moreover, the rotation of the rotor also creates a swirl of air inside the chamber 12, which, due to the selection of air from the upper part of the housing 8, causes air circulation in the housing through the rollers, as well as through the separator chambers. This air circulation, assisted by suction devices (not shown), combined with a pneumatic conveyor, cools the rollers as well as the milled material.

Thus, the present invention allows to solve the problems and provide many advantages compared with previously known technical solutions.

The first advantage is that by directly feeding the milled material to the mill sifting apparatus of the present invention (falling by gravity), no conveyor and / or lifting means are needed to power the device, which simplifies the design and increases system efficiency due to energy and power savings.

The second advantage is that due to the fact that the material milled by the rollers falls onto the screening surface of the sieve essentially in the form of a continuous "film", which is uniform along the entire axial length of the rollers, and the material covers tangentially (figure 2) the surface sifting the sieve with a uniform and uniform distribution, without excessive receipt or interruptions in the supply of material, an increase in the yield of the material and a reduction in operating costs are achieved.

Another advantage is that the air circulation created by the rotation of the screening device in accordance with the present invention contributes to the continuous cooling of the rollers and the grain itself, which can be heated during grinding operations, while the chemical and physical characteristics of the grain are kept constant and an increase in the resulting efficiency of the mill is achieved. Moreover, air circulation improves homogenization of the product during grinding operations.

Another advantage is that the mill in accordance with the present invention allows for complete sorting of the milled product without the use of an additional sorting unit (sieving) or screeners after the mill.

The installation installation costs are also reduced, since the mill s in accordance with the present invention occupies a smaller volume than previously known systems in which the presence of sieving units or other similar devices requires an increase in vertical size by 3-4 times.

Claims (11)

1. Roller mill for grinding and sorting bulk materials containing at least one pair of rollers rotating in opposite directions (2), between which a gap (3) is formed for the passage of material to be crushed, and a screening device (10) combined with rollers (2) for separating grinding products in accordance with the particle sizes of the milled material, and the screening device (10) has a screening surface (14a) located below the rollers (2) in such a position that it is not bent on it a material milled by means of rollers (2) falls substantially under the influence of gravity, characterized in that it contains conveyor means (19) embedded between the rollers (2) and the screening surface (14a), for guiding the material coming under the action of gravity and falling from the rollers, along the path of falling onto the screening surface (14a), said path extending essentially tangentially to the surface (14a). 2. A mill according to claim 1, characterized in that the screening device (10) comprises a first chamber (12) into which material crushed by rollers (2) falls, a second chamber (13) separated from the first chamber (12), and communicating with it by means of a screening surface (14a), the second chamber (13) being used to collect material sifted by means of the surface (14a). 3. Mill according to claim 2, characterized in that the mixing means (15, 16) are made in the first chamber (12) for mixing and moving the rejected material from the screening surface (14a) in the discharge direction (21) from the first chamber (12) . 4. The mill according to claim 3, characterized in that it contains the first conveyor means (22) for lifting the milled material, rejected using the screening surface (14a) and discharged through the outlet (21), into the feed hopper (5) for subsequent additional grinding with rollers (2). 5. Mill according to claim 3, characterized in that the mixing means comprise a rotor with blades (15) and a screening surface (14a) located at least partially along the portion of the path of rotation of the blades (16). 6. Mill according to claim 5, characterized in that the axis of rotation of the rotor (15) is essentially parallel to the axis of rotation of the rollers (2). 7. The mill according to one of claims 1 to 4, characterized in that the second conveyor means (24, 25) is combined with the outlet (23) of the second chamber (13) to move the material separated by the screening surface (14a). 8. The mill according to claim 7, characterized in that the conveyor means is pneumatic or mechanical. 9. Mill according to claim 7, characterized in that an air intake is integrated with the second conveyor means (24, 25). 10. Mill according to claim 9, characterized in that the air intake has one or more inlets (8c) located higher in the direction relative to the rollers, and the rotor speed (15) is selected so as to induce forced air circulation through the rollers (2 ) 11. The mill according to one of claims 1 to 10, characterized in that the screening surface (14a) is fixed in the screening device (10) with the possibility of disconnection.

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