SU1645034A1 - Vibratory screen - Google Patents

Abstract

This invention relates to a technique for separating materials by size and can be used in the coal, mining, construction, and other industries. The purpose of the invention is to improve the quality of separation and increase the efficiency of the operation of the screen. The box 1 of the screen is made with cross beams 2 interconnected by means of longitudinal links (PS) 3. At PS 3 by means of elastic elements

Description

1

Combi (CI) 6, subsite supports 7 are installed with sections (C) 8-10 of screening sieve 11 fixed on them, which are mounted relative to each other with a gap. The rigidity of the UE 6 under each subsequent C from the beginning of the sieve along the length of the sieve 11 is greater than the rigidity of the UE of the previous C (2.7-2.72) times. The UE b hardness of the first C 8 is determined by the ratio C Cf (1 - e) / (1-ew), where e is the base of the natural logarithms, C p is the total stiffness of the elastic bonds, k 1.8 is the coefficient depending on the properties of the screened material, n is the number of C sieves along the length of the screen. The inertia exciter 4 communicates duct 1 with transverse beams 2 directed oscillations at an angle to C 8-10. By means of PS 3 and UE 6, oscillations are transmitted to submount supports 7 with C 8-10 performing directional in-phase movements with respect to duct 1. An increase in the rigidity of the C8-10 connection is 1 box (2.7-2.72) K times G for each subsequent C It is impossible to obtain diminishing amplitudes of oscillations of these C, sufficient for loosening the material layer. The rigidity of the first C 8 sieve 11 and its pitch for subsequent C 9, 10 allows the total stiffness to be distributed along the length of the sieve 11, which makes it possible to excite with the most rational amplitude for 8-10. 2 Il.

This invention relates to a technique for separating materials by size and can be used in the coal, mining, construction, metallurgical and other industries,

The purpose of the invention is to improve the quality of separation and increase the reliability of the operation of the screen.

1 shows a schematic representation of a vibrating screen | figure 2 - section aa in figure 1.

Vibrating screen contains box 1 with transverse beams 2 interconnected by longitudinal links 3. In box 1, an inertial vibration exciter 4 is rigidly fixed. Box 1 is installed on the foundation with shock absorbers 5. On the longitudinal links x 3, elastic elements 6 are installed supports 7 with sections 8-10 of the screening surface (sieve) 11j fixed on them, these sections having the same overall dimensions as well as mass to prevent their turning oscillations and the oscillation system galloping for the purpose m. The elastic stiffness of the sections 8-10 of the sieve 11 is set by the set of elastic elements 6 in such a way that it increases (2.7-2.72) times along the length of the screening surface 11 from the loading section 8 to the unloading 10, and the stiffness of the elastic elements of the first section 8 is determined by the formula

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0

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0

five

0

five

g - - (1-S)

Where e is the base of natural logariths — 4 months;

 stiffness of elastic elements

the first section of the sieve; C - total elastic stiffness

connections, K is a coefficient depending on

the properties of the material being blasted, n is the number of sieve sections according to

the length of the screen.

With an increase in the stiffness of the second section 9 of the screening surface 11, less than 2.7 times the amplitude of its oscillations will be high, which will allow; effectively loosening and classifying the layer of material in this area, however, the speed of vibro-transport also increases, which does not change the amount of material in the subsequent section. The communication stiffness of the remaining sections 9.10, with the screen of screen 1 will increase by more than 2.72k times, since the total rigidity of all the elastic connections for this screen design remains constant. The amplitude of oscillations of these sections will be small and insufficient to completely loosen the layer of material. The efficiency of classification is sharply reduced. An increase in the rigidity of the second section 9 of the no-i screening surface 11 by more than 2.72K times will lead to a decrease in the amplitude of oscillations of this section 9, which is insufficient to completely loosen the material layer and the passage of small grains in the upper layers directly to the sieve 11, which reduces the efficiency of screening.

Thus, an increase in the rigidity of the bond of each subsequent section 9 and 10 of the screening surface 1 with the screen of the screen 1 less than 2.7 times leads to useless energy losses in the classification process in the area under consideration, and as this rigidity increases by more than

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2.72 times, the amount of energy is not enough to completely loosen the layer of material.

- The coefficient K for bulk materials of various particle size distribution and physicochemical properties varies widely and roughly takes values of the order of 0.2-1.8. For example, for sifting coal with external moisture up to 4% for a class of 13 mm and a fine class content of 50% in the starting material, the coefficient k can be taken equal to 1.

The required stiffness value of the elastic connections of the individual sections 8-10 of the screening surface 11 can be set, for example, using blocks consisting of individual elastic elements 6. The number of elastic elements 6 in the blocks per section of the sieve will determine the stiffness value elastic coupling of this section with cob 1 of rumble.

Sections 8 to 10 of the screening surface 11 are installed with a clearance relative to each other to prevent mutual collision and ease of screen assembly. The gaps overlap with pieces of elastic tape 12, for example, conveyor belt, to ensure that the oversize material is transferred from one section 8 of the sieve 11 to the other 9 and prevent them from seizing up in large pieces.

The roar works as follows.

An inertial vibration exciter 4 communicates box 1 with crossbeams 2 directional oscillations at an angle to sections 8-10 of the screening surface 11. Through the longitudinal links 3 and the elastic elements 6, oscillations are transmitted by the sump support 1

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frames 7 with sections 8-10. the screening surface 11, which makes directed movements relative to the screen box 1 of the screen, and the vibrations of all sections 8-10 are sieves 11 of the common mode. Establishing the rigidity of the connection of sections 8–10 sieves 11 with jpoxoTa box 1 using elastic elements 6 with an increase in it (2.7–2.72) for each subsequent section along the length of the screening surface 11 makes it possible to obtain different oscillation amplitudes of these sections. The amount of oscillation of the sieve sections is the smaller, the greater the stiffness of the elastic connection. The total stiffness of the elastic connections of all sections 8-10 of the screen 11 does not depend on their number and remains constant for a given mode of vibration.

The angular speed of rotation of the shafts of the vibration exciter 4 is established close to the -frequency of the natural oscillations of the subsite supports 7 with sections 8-10 of the screening surface 11 on the elastic elements 6. Due to this, the roar works in the antiresonance mode, i.e. sections 8-10 of the screening surface 11 are dynamic oscillation dampers of box 1 on shock absorbers 5. At the same time box 1 remains almost motionless and dynamic loads on the foundation are not transmitted. The location of the elastic elements 6 on the longitudinal links x 3 significantly increases the frequency of near-resonant vibrations of the screen by increasing the total stiffness of the elastic connection of the box 1 with the screening surface 11 without significantly reducing the effective screening area of the screen, and also install sections 8-10 of the screening 5 surface 11 lightweight design. Thus, the deflections from the bending vibrations of the subsurface supports 7 with sections of the screening surface 11 become minimal, since the loads from their own inertial forces are small with a small length and weight of sections of the sections of the sieves 8. For the same length of the screening surface 8, the value Bending from bending vibrations will be less, the greater the number of sections 8-10 it will consist of. The reliability of the screen rises by the same number of times. Insignificant

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on the deflections of sub-supports 7 with sections 8-10 of the screening surface 11, it is possible to stabilize the absolute values of the amplitudes of oscillations of sections 8-10 of the screening surface 11 along the length and width of the screen. The raw material enters the first section 8 of the screening surface 11 at the loading part of the screen and, under the influence of directional vibrations, is loosened, mixed, classified and transported along it. The transfer of the oversize material from one section 8 of the sieve 11 to the other 9 is provided by an elastic band 12. On the loading section 8 of the sieve 11, the elastic bond of which is minimal, the thickness of the layer of material being classified is maximum here and the oscillation amplitude of this section 8 is maximum 11, allowing the layer of material to be fully loosened and effectively classified. Most of the passage fractions of the starting material already in the first sections 8 and 9 of the screening surface 11 go under the sieve and in the subsequent sections 10 the value of the layer of material becomes smaller. The oscillation amplitude of these sections 10 is also smaller, but its magnitude is sufficient to loosen the layer of material located on these sections 10. At a constant frequency and a decreasing amplitude of vibrations, the rate of vibrotransport of the superlattice material decreases, therefore, the classified material is in contact more time with the sifting surface 11 , which allows to increase the efficiency of classification. During the advance of the oversize material in sections 8-10 of the screening surface 11 along the screen, its layer gradually decreases as the passage fraction under the sieve elapses, while the elastic connection in sections 9.10 of the screen 11 with screen 1 and the screen decreases proportionally. a section that is large enough to loosen a layer of material. The proportionality of the change in the stiffness value of the elastic connection of sections 9 and 10 of the screening surface 11 is ensured by controlling the number of elastic elements 6 by an amount of (2.7-2.72) times

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0

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for, and the elasticity of the elastic bond of the first section 8 is determined by the known formula, where the coefficient k depends on the grain content of the passage fraction in the starting material, the properties of the material itself and a number of other factors (humidity, grain shape, size and shape of the sieve holes and t . e.) The stiffness of the elastic coupling of the first section 8 of the screening surface 11 is set depending on the excited inertia force of the vibration exciter 4 and the number of sections 8-10 of the sieve 11 along the length of the screen, since this inertia force determines the total stiffness of all the elastic x connections. The greater the number of sections 8 to 10 will consist of the screening surface 11, the less will be the rigidity of the elastic connection of the first section 8 of the sieve 11 with the screen box 1. The total stiffness of all elastic connections of sections 8-10 of the screening surface 11 remains constant for any number of them and is determined only by the design parameters of the screen itself. The formula for determining the stiffness of the elastic connection of the first section 8 of the sieve 1t and the step of changing it for the subsequent sections 9 and 10 take into account the distribution of the total stiffness along the length of the screening surface 11. Thus, the distribution of the stiffness of the elastic connection of the sections 8-10 of the sieve 11 with the duct 1 according to the proposed dependence, it allows one to excite oscillations with the most rational amplitude for the corresponding sections 8 - 10. In addition, taking into account the properties of the material will allow to achieve the maximum screening effect at the established level of dynamic mode intensity.

Claims (1)

Invention Formula Vibrating screen, including a box with transverse beams mounted on shock absorbers interconnected by means of longitudinal links with elastic elements, a screening surface mounted on elastic elements of longitudinal links by means of sub-supports, and an exciter mounted on the box, characterized in that in order to improve the quality of separation and increase the reliability of operation of the rokho 916450 The screening screen is divided into equal sections, set relative to each other with a gap, while the stiffness of the elastic elements under each subsequent section from the beginning of the sieve along the length of the screening surface is greater than the elasticity of the elastic elements under the previous section (2.7-2.72 ) times, when-10, the stiffness of the elastic elements under the first section is determined by the ratio 10 CfcO-еЪ . H IP 1st m de e is the base of the natural logarithm; C, is the total stiffness of the elastic elements of all sections; , 21, 8 is a coefficient depending on the properties of the material being shaken; n is the number of sieve sections along the length of the screen. Aa K 7 11 I / i Г Ш FIG. 2