RU2406569C2 - Crusher - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: crusher consists of housing and cover that make crushing chamber, rotor, two stud disks, feeder with magnetic latch, metal collector and pneumatic receiver. Said disk revolve in opposite directions at different rpm, drive by planetary gear. Stud secured to said disks feature wing-like shape. Direction of wings on one disk is opposes that of wings on the other disk. There is an auger fitted on the shaft to force crushed material in between revolving disks.

EFFECT: intensified crushing, reduced power consumption, reduced wear and higher quality.

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Description

The invention relates to the food industry and can be used for grinding fruit, fruit and other edible plant and animal raw materials.

In the food industry, grinding is used for the following purposes: to prepare raw materials for cooking, to give the product the required consistency, portioning of the product, disposal of raw waste and food residues, to increase the surface of solid materials in order to increase the speed of biochemical and diffusion processes in the processing of fruits, vegetables and etc. Grinding is used in milling, meat, beet sugar, alcohol, brewing, canning and other industries.

The closest in technical essence and the achieved effect is a dismembrator [Antipov S.T. Machines and equipment for food production (textbook with bar) [Text] / S.T. Antipov, I.T. Kretov, A.N. Ostrikov, V.A. Panfilov, O.A. Urakov. - M .: Higher school, In 2 volumes, Vol. 1. - 2001. - 703 s], consisting of a housing that forms, together with a hinged lid, a working chamber, a rotor with a removable pin disk, a fixed disk with pins mounted on the cover, a feeder with magnetic protection, a metal collector and a pneumatic receiver.

The disadvantages of the known dismembrator are:

- the difficulty of maintaining a given dispersed composition of the crushed particles due to the lack of an adjustable size of the working gap between the pins located on the removable and fixed disks;

- high specific energy consumption of the grinding process, due to the lack of the possibility of reducing the duration of the technological cycle;

- significant specific load on the working body of the dismembrator (pins) due to the irrational power circuit of the product on the surface of the pins;

- the inaccuracy of the selected geometric and kinematic parameters of the dismembrator causes increased wear of the working bodies (disks with pins), which can lead to their premature failure.

An object of the invention is the intensification of the grinding process, reducing the specific energy consumption of the process by reducing the duration of the technological cycle, reducing the specific loads on the pins due to the use of a rational power scheme of the product on the surface of the wing-shaped pins, reducing the mechanical wear of the disks with pins due to the scientifically based selection of geometric and kinematic parameters of the working bodies of the crusher, maintaining a given dispersed composition, we obtain of the product, which has a positive effect on the quality of the finished product to be ground.

The technical task of the invention is achieved by the fact that in the crusher, consisting of a housing that forms, together with the lid, a working chamber, a rotor, two pin disks, a feeder with magnetic protection, a metal collector and a pneumatic receiver, it is new that both disks are rotatable in opposite sides with different speeds using a planetary gear, the pins mounted on the disks have a wing-shaped shape, and the direction of the wings on one disk is opposite to the direction of the wings on ugom disc crusher housing in the shaft is a screw for forcing the crushed product to a zone between the rotating discs.

The technical result consists in improving the grinding quality by obtaining a predetermined dispersed composition of the crushed particles of the product, reducing the specific energy consumption of the process by reducing the duration of the process cycle, reducing the specific loads on the pins due to the use of a rational power scheme of the product on the surface of the wing-shaped pins, reducing the mechanical wear of the disks pins due to the scientifically based selection of geometric and kinematic parameters of the working x crusher bodies.

Figure 1 shows a cross section of a crusher; figure 2 is a left view of the crusher; figure 3 is a view of I in figure 2; figure 4 - view In figure 3.

The crusher (Figs. 1 and 2) consists of a housing 1, which forms, together with the lid 2, a working chamber 3, a shaft 4, disks 5 and 6 with pins 10 mounted on them, a feeder 7 with magnetic protection, an electric motor 16, a metal collector 8, an air receiver 9 , the loading pipe 15 and the planetary gear. A planetary gear train consists of a leading central gear wheel 11, a stationary central gear wheel 18, a driven carrier 17 and three satellites 13, rotating together with the axles 12 around the shaft 4. A disk 5 is rigidly mounted on the driven carrier 17.

The planetary gear transmission provides the opposite direction of rotation of the carrier 17 (and, consequently, the disk 5) and the central gear 11, on which the disk 6 is rigidly mounted, since the gear ratio i has a negative value:

where z ₁ and z ₃ - respectively, the number of teeth of the gears 11 and 13.

A pin disk 6 and a screw 14 are fixed on the shaft 4 for forcing the crushed product into the area between the rotating disks 5 and 6 (Fig. 2).

The pins 10, mounted on the disks 5 and 6, have a wing-shaped shape, and the direction of the wings on the disk 5 is opposite to the direction of the wings on the disk 6 (Fig.2 and 3).

The wing-shaped shape of the pins 10 and their opposite direction on the disks 5 and 6, rotating in opposite directions with different speeds ϖ ₁ and ϖ ₃ , is explained by the following considerations.

It is known that the following grinding methods exist: crushing, splitting, breaking, cutting, sawing, abrasion, grinding by impact [Processes and Food Production Equipment [Text]: Textbook. for universities: in 2 books. / A.N. Ostrikov, Yu.V. Krasovitsky, A.A. Shevtsov, and others; under the editorship of A.N. Ostrikova. - SPb .: GIORD 2006. - Book 1. - 632 p.]. In this crusher, the above grinding methods are implemented.

When cracking, bending stresses occur mainly in the product. The splitting process is carried out by creating large concentrations of loads at the contact points of the product with the wedge-shaped working element (wing-shaped pins), which is affected by force. When large particles of the product fall into the area between the pins 10, their sharp edges precisely split the product into smaller particles.

The process of breaking occurs due to the action of bending forces on the crushed particle when it gets between the pins 10. The size and shape of the resulting particles are approximately the same as when cracking.

When crushed under the action of a static load created by the force on the product, the compressive stresses are decisive. Under their action, the product is deformed throughout the volume. In this case, the internal stress in it gradually rises and upon reaching the internal stress above the compressive strength, the product is destroyed. In this case, particles of various sizes and shapes are formed. Crushing is carried out by the lateral faces of the pins 10 during their mutual oncoming movement (see position I, position II and position III of pin 10 in FIG. 3).

With abrasion, failure occurs mainly from shear stresses. The product is subject to forces arising from the movement of the pin disks 5 and 6 in opposite directions. Abrasion in combination with crushing is one of the most economical methods of grinding, and it is used to the maximum extent in the proposed design of the crusher.

The crushing process due to impact is carried out under the action of dynamic loads on the product, as a result of which dynamic stresses arise, leading to its destruction. With a constrained impact (as in the proposed crusher), the body is destroyed between two working bodies (disks 5 and 6) of the crusher, with a free one - as a result of a collision with the working body (pins) or another crushed product particle.

The proposed design solutions for pins 10 and discs 5 and 6 allow you to implement the above combination of grinding methods. For example, in the working chamber 3, abrasion is accompanied by crushing, splitting, grinding upon impact.

Thus, the developed design combines several methods of grinding products. However, depending on the final tasks of the grinding process, certain conditions must be met. First of all, the product must be crushed to the required size. Uniform crushing of products to a certain size depending on its type helps to minimize energy consumption and increase the productivity of the crusher. The presence of dust particles leads to increased losses of the product along with the exhaust air (during pneumatic transportation), worsens the environmental situation, causes excessive energy consumption, etc. The choice of the relative positions of the pins 10 on the disks 5 and 6 ensures the grinding of the product from d _n to d _to (figure 3), i.e. to the required particle size with a minimum content of dust particles.

The combination of several grinding methods implemented in this crusher causes minimal heating of the product during the grinding process.

The main criteria for evaluating the effectiveness of the food grinding process are: the degree of grinding, the specific energy consumption of the process and the specific load on the working body of the crusher.

An important criterion for evaluating the efficiency of the grinding process is the specific energy consumption

where ΔA is the work spent on grinding the product with the initial surface area S _n to the final surface area of the crushed particles S _to (kg · m / m ² ).

To reduce the energy consumption of the grinding process in the proposed design of the crusher, the product turnover in the technological process is reduced, rational modes of preparation and grinding of the product are used, the duration of the technological cycle is reduced, the geometric and kinematic parameters of the grinding working bodies (pins 10 and disks 5 and 6) are correctly selected.

The proposed crusher operates as follows.

The electric motor 16 of the crusher is turned on, the shaft 4 with the disk 5 mounted on it and the screw 14 is rotated. At the same time, a driven carrier 17 is driven into rotation through a planetary gear train using a driving central wheel 11, a fixed central wheel 18, and three satellites 13 with a disk 6 mounted on it around the shaft 4.

The product through the loading pipe 15 enters the feeder 7 with magnetic protection, where there is a selection of metallomagnetic impurities sent to the metal collector 8, after which it enters the center of the working chamber 3.

The product purified from metal impurities is captured by the rotating screw 14 and pumped into the zone between the rotating disks 5 and 6. Here, the product is crushed when it passes through the gaps between the pins 10 located on the rotating disks 5 and 6. Due to the fact that the pins 10 have a wing-shaped shape, a gradual decrease in the working gap between them occurs when the disks 5 and 6 rotate (see position I, position II, and position III of pin 10 in FIG. 3). This is due to the fact that the direction of the wings of the pins 10 on the disk 5 is opposite to the direction of the wings of the pins 10 on the disk 6 (figure 4).

In the proposed crusher, the grinding process is carried out sequentially. Using the differences in the structural and mechanical properties of the constituent parts of the product being ground, each stage of the process is carried out so that particles are obtained that differ from each other in certain physical properties. This further facilitates the separation of the granular mixture by separation into fractions, each of which consists of particles more or less uniform in composition. For example, grinding wheat and rye into varietal flour is based on the use of differences in the structural and mechanical properties of endosperm and shells, which increase even more after hydrothermal processing of grain. In order to prevent excessive grinding of the shells, the method of selective grinding of grain and its particles is the basis for the construction of complex grinding. This method, combined with the optimal forms of the working bodies of the grinding machines and their kinematic parameters, allows the process to be carried out in such a way that crushing of the shells can be minimized and the maximum amount of endosperm can be extracted from the grain. Output, i.e. the extraction of flour, as well as its quality, largely depends on the perfection of the process of grinding grain. With excessive grinding, the productivity of the crusher decreases, the energy consumption increases and, therefore, the cost of production increases.

Thus, the degree of grinding of the product depends on the proper construction of the process, which makes it possible to rationally use the raw materials, increase the uniformity of the obtained product particles, increase the crusher productivity, reduce the specific energy consumption, and reduce the cost of the finished product.

The process of deformation and grinding of the product is accompanied by the expenditure of energy. It is spent on the formation of elastic and plastic deformations, overcoming the forces of molecular cohesion, after which large particles are destroyed, and new smaller particles with a larger total surface are formed. Both in elastic and in plastic deformation, a partial conversion of mechanical energy into thermal energy occurs. As a result, the temperature of the deformable particle of the product rises. In addition, energy is spent on overcoming the resistance in the crusher (friction and deformation of parts, their heating, etc.).

Energy costs for grinding products depend on the physico-mechanical properties of the product being ground (tensile strength of the material a _P , its elastic modulus E); geometric parameters (volume or linear size); degree of grinding; the selected grinding method, as well as the performance of the crusher.

The full work A of external forces during crushing is expressed by the generalized Rebinder grinding law

where A _o is the energy spent on the processes of deformation and formation of wear products of the working bodies of the crusher, N · m; σ _p - breaking stress of the crushed product, N / m ² ; V is the volume of the crushed product, m ³ ; E is the modulus of elasticity of the crushed product, N / m ² ; m _y - the number of cycles of deformation of the particles of the crushed product; k _p - energy for the formation of 1 m ^{2 of a} new surface for this product, N / m; ΔS = S _to -S _n - newly formed surface (S _to , S _n - respectively, the total surface of the product before and after grinding), m ² ; α is a dimensionless coefficient characterizing the process of formation of a new surface for a crusher of this design:

here n is an exponent depending on the grinding conditions (for fine grinding n> 0).

From equation (3) you can determine the efficiency of the grinding process

The efficiency of the grinding process increases:

- with a decrease in the value of A _about , i.e. reducing elastic deformations of the material of the working body (pin disks 5 and 6) of the crusher and increasing their wear resistance, optimizing mechanical and kinematic parameters, as well as increasing its wear resistance;

- reducing the number of deformation cycles m _{in the} particles of the product being ground (reducing the length of the process and simplifying its scheme);

- reduction of destructive stresses σ _{p of the} crushed product;

- obtaining the fractional composition of the finished product (flour, cereal, etc.), due to the intended use, limiting the particle size, as excessive grinding leads to an increase in ΔS and α, and therefore to additional energy costs.

The crushed product enters the pneumatic receiver 9 and is removed from the crusher by a pneumatic conveyor.

Thus, the use of the proposed crusher allows you to:

- to obtain crushed particles of a given dispersed composition by adjusting the size of the working gap between the pins 10 on the disks 5 and 6;

- reduce the specific energy consumption of the grinding process due to the reduction of the duration of the technological cycle;

- reduce the specific load on the pins 10 due to a more rational power scheme of their action on the crushed product;

- reduce the wear of the pin disks 5 and 6 due to the correct selection of geometric and kinematic parameters of the crusher.

Claims (1)

Crusher, consisting of a housing that forms, together with the lid, a working chamber, a rotor, two pin disks, a feeder with magnetic protection, a metal collector and a pneumatic receiver, characterized in that both disks are rotatable in opposite directions at different speeds using a planetary gear , the pins mounted on the disks have a wing-shaped shape, and the direction of the wings on one disk is opposite to the direction of the wings on the other disk, a discharge screw is located in the crusher body on the shaft I grind the product into the area between the rotating discs.

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