RU2014910C1 - Method and device for size-grading of grain materials - Google Patents

Abstract

FIELD: separation of friable materials. SUBSTANCE: during reciprocating motion of screen the brushes are made to move so that they periodically break contact with screen surface. Grains sticking in screen meshes are acted upon when screen stops in the lowermost position, inclining brush axles along screen trajectory. This nature of motion is provided for by introducing crank gear, ratchet mechanism and vertical endless chain into brush cleaner drive. EFFECT: improved functional and operating characteristics. 2 cl, 1 dwg

Description

 The invention relates to techniques for the separation of bulk materials and can be used in agriculture, as well as other sectors of the economy using sieve cleaning and sorting machines.

 A known method of separating bulk materials, including feeding material to a sieve, making oscillatory movements, sifting small particles through sieve openings, acting on stuck particles by elastic working bodies pressed to the sieve moving relative to the sieve surface at a constant speed, and squeezing stuck particles out of holes (Gladkov N.G. Grain-cleaning machines (design, calculation and operational data), Moscow: MASHGIZ, 1950, p. 290).

 The disadvantages of this method include the inability to ensure high efficiency of sifting sieves, the rapid abrasion of the brushes, the inability to install a sufficient number of sieves in a small volume.

 The first drawback is caused by the fact that the brushes themselves close the sieve openings and reduce its live section. In addition, the pressing of the brushes to the sieve causes the bunches of hair to bend and the force transmitted by the stuck particles to them is substantially less than the maximum critical value that the brushes can transmit when the buns are located directly. As a result, some particles get stuck in the holes so badly that the curved tufts of brush hair cannot push them out of the hole. In addition, when moving the brush in one direction relative to the surface of the sieve, the stuck particles are moved by the brushes along the hole to its end edge, which contributes to a greater jamming of the particles.

 The second disadvantage is due to the continuous friction of the brushes pressed to the sieve during the entire operation of the cleaning machine. In this case, both the abrasion of the brushes and the hair cut from the edge of the holes occur.

 The third disadvantage is due to the fact that the devices for implementing the method comprise a chain transmission located between the sieves with brushes fixed to the links. This does not allow the sieves to be installed close to each other and leads to an increase in the overall dimensions of the machine as a whole.

 Closest to the proposed technical essence and the achieved effect is the method of separation of grain materials (ed. St. USSR N 994051, class B 07 B 1/52, 1981), including feeding the material to the sieve, reciprocating, sieving fine fractions through sieve openings, periodically repeated exposure of sieve cleaner brushes to grains stuck in its openings, and removal of separation products.

 The specified method can be carried out in the presence of a single-row placement of brushes between sieves, i.e. with a minimum distance between them. Therefore, the third of these disadvantages is eliminated.

During the reciprocating movement of the brushes, the particles jammed at the extreme points of the oblong holes are pulled out by the brushes into the central region of the holes, where it is easier to extrude them. However, the movement of the brushes occurs with short stops during which the cleaning process of the sieves stops. Thus, the following disadvantages remain:
the inability to ensure high efficiency of screening sieves;
intensive wear of tufts of hair brushes.

 The purpose of the invention is to increase the efficiency of sifting and reduce wear of the working elements of the brushes - hair bundles.

 This goal is achieved by the fact that in the known method, which includes feeding the material to the sieve, reciprocating, sifting the fine fraction through the sieve holes, periodically repeated exposure of the sieve cleaner to the grains stuck in its holes, giving the reciprocating movement of the sieve give an inclined the trajectory, the effect of brushes on grains stuck in the holes of the sieve is carried out while the sieve is stopped in its lowest position, giving the brush axes a tilt in the tilt direction and the trajectories of the sieve.

 It is obvious that according to the proposed method, during the cycle of operation, the brush cleaner only comes into contact with the sieve for a short time at the moment of direct extrusion of particles from the holes. Most of the brush cycle does not contact the sieve and does not close its free holes.

 At the moment of contact with stuck particles, the tufts of the brush hair are in an undeformed (direct) state. Therefore, when pressed, the maximum possible critical force develops, determined by the stability of the beam. In the known method, the tufts of hair are bent before interacting with stuck particles. Therefore, obviously there is a loss of stability of the hair bundles and the force of their impact on stuck particles is much less.

 A prerequisite for cleaning the sieve according to the prototype is the presence of protrusions of sunken particles in the holes above the surface of the sieve, since the hair is bent and drawn to the sieve of the hair bundles are tangent to the specified surface. For example, for fine-grained materials, the particles of which are stuck in the holes with almost no protrusions, the existing method is ineffective. According to the proposed method, hair bundles pass through the sieve holes through a vertical movement, squeezing particles from the holes that do not protrude above the surface of the sieve.

 There are known sieves which, in order to increase the living cross section and intensify screening, have a spatial configuration of the holes. The particles stuck in such an opening have a spatial area of contact with the sieve, often without protruding above its surface. Unlike the prototype, the proposed method is effective and it provides for the impact on stuck particles in the direction of sieve vibrations. In this case, the impact slope is determined by the geometric features of the structure of the sieve openings from the conditions of the best wedging of particles.

 The wear of the brushes sharply decreases, since friction of the brushes against the sieve is excluded, the contact time of the brushes with the sieve is significantly reduced, not all hair bundles are bent upon contact, but only part of them, which abuts against the jumpers of the sieve openings.

 It follows from the foregoing that the absence of at least one of the proposed distinguishing features does not allow to obtain a positive effect and, at the same time, all the signs are sufficient to achieve the set goal - increasing the sieving efficiency and reducing the wear of the beams.

 Comparison of distinctive features with the prototype convinces that these features are new.

 The drawing shows a structural diagram of a device for separating grain materials according to the proposed method.

 The technological process of separation of the material according to the proposed method is as follows.

 The sieve 17 installed in the casing of the sieve mill 4, give an inclined path. The brushes 14, mounted on the carriage 15, are installed obliquely so that the axes of the hair bundles coincide in the direction of sieve oscillation 17. The connecting rod 1 of the sieve cleaning device is connected to the crank 2 of the drive of the sieve mill 4 in such a position that the start of the working stroke of the ratchet wheel 7 and the moment the neutral position of the sieve mill 4 during its rise coincided in the phase of movement. The gap between the carriage 15 and the sieve 17 is set so that the brushes 14 do not come into contact with the sieve 17 in the neutral position of the sieve mill 4. Then, when the sieve mill 4 is lifted from the neutral position for at least half its oscillation period, the brushes 14 interact with the sieve 17 excluded. In the specified period of time by the thrust 13, the carriage 15 is moved horizontally with the brushes 14 along the guides 16. When lowering the sieve mill 4, the brushes 14 and the sieve 17 come together. At the moment the sieve 17 passes through the neutral position, the horizontal supply of brushes 14 is stopped. Therefore, in relative motion, the brushes are fed to the sieve in the direction of the line of oscillation of the mill, which coincides with the direction of the axes of the hair bundles in an undeformed state. The contact of the brushes 14 with stuck particles occurs near the bottom dead center point of oscillation of the sieve 17, where it is stationary. Brushes 14 pass through the holes of the sieve 17 and free the holes from stuck particles in the area of their contact. Each cycle of oscillations of the mill 4 is accompanied by a working cycle of cleaning the sieve 17. In this case, the area of the sieve located between the brushes is cleaned by moving the carriage along the sieve along the guides.

 It should be noted that the sieve cleaning cycle is carried out at the moment when the sieve goes to the lower position, tossing a layer of the processed material on it. At this moment, the sifting of particles through the holes does not occur. Therefore, unlike the prototype, the overlapping of the free holes of the sieve with brushes during the cleaning of the holes of the sifting of the sieve does not worsen.

 A device is known for separating grain materials (ed. St. USSR N 994051, class B 07 B 1/52, 1981), including a sieve installed in a housing with the possibility of reciprocating movement on brush sieve cleaners, hair bunches of which can pass through sieve holes.

The disadvantages of this device include:
lowered efficiency of sifting of bulk materials through cleaned sieves;
intensive wear of tufts of hair brushes.

 The first drawback is due to the fact that the brushes, being in constant contact with the sieve, cover part of the free holes, as well as the fact that the force exerted by the curved hair of the brushes is not enough to remove particles that are strongly stuck in the holes.

 The second one is that the brushes pressed to the sieve, in the process of work, continuously rub against its surface and, therefore, are quickly worn away.

 In the proposed device for separating grain materials according to the proposed method, the sieve is installed with the possibility of movement along an inclined path, the sieve drive contains an engine with a crank mechanism, brush cleaners are mounted on a carriage mounted in the sieve mill body on rails parallel to the sieve plane, the wiper brushes have slope towards the slope of the trajectory of the sieve, the brush cleaner drive has a crank drive connected by a ratchet mechanism to the sieve drive tunny mechanism vertically and closed circuit enclosing two sprockets, one of which is rigidly connected with the ratchet wheel of the ratchet mechanism, wherein one of the links of the endless chain associated with the carriage of the sieve cleaner via a connecting rod hinged at its ends.

 The device consists of a connecting rod 1, connected at one end with a crank 2, connected to the engine and drive 3 of the sieve mill 4, and the other, with a lever 5, which drives the ratchet wheel 7 through the dog 6, which is rigidly fixed to the shaft 8 together with the drive sprocket 9, connected to the additional sprocket 10 by the chain 11. One of the chain links through the ring 12 and the rod 13 is connected to the working bodies (brushes 14), mounted on the carriage 15, which is mounted with the possibility of movement along the fixed guides 16. The brushes 14 are mounted continuously axes of beams in the direction of hair oscillation sieve 17. The connecting rod 1 and connecting rod drive mechanism 3 sieve box 4 connected to the crank 2, so that the beginning of the working stroke of the ratchet wheel and the neutral point sieve box when it is being raised by combined movement phase.

 The proposed device operates as follows.

 When the engine is turned on, the crank 2 of the drive mechanism 3 is informed of the movement. The drive mechanism 3 drives the sieve mill 4 and the lever 5 in oscillatory motion. At the moment of lifting the sieve 17 from the neutral position, when there is no contact of the brushes with the sieve, the ratchet wheel 7 moves. This is ensured by the fact that the beginning of the wheel 7 stroke and the neutral moment of the sieve mill 4 coincide when it is lifted. The ratchet wheel 7 rotates the shaft 8 together with the drive sprocket 9 of the chain 11. Having received the movement, the chain 11 moves the carriage 15 through the guide 13 along the guide 16 along the sieve 17. The carriage 15 moves to a stop during the half-cycle of the sieve 17 when the crank 2 of the drive 3 will turn half a turn. During this time, the sieve 17 rises to the top dead center and again falls into a neutral position. The layer of the processed material on the sieve is thrown up. The subsequent half-turn of the crank 2 corresponds to the idling of the lever 5 of the ratchet wheel 7 with the stationary carriage 15 with brushes 14. The sieve 17 continues to lower. Near the bottom dead center, it bumps into the tufts of hair of the brushes 14, which abut the stuck particles and squeeze them out of the holes of the sieve 17. Next, the sieve 17 together with the sieve mill 4 rises again, the contact of the brushes 14 with the sieve 17 ceases, and with the processed material, which is in flight above the sieve, is restored, sieve 17 is ready for sifting. Subsequent cycles of the device are similar. In the process, the carriage makes a return movement. The amount of movement between the extreme points depends on the intercenter distance of the chain 11 and is set based on the calculation of the required overlap of the influence areas of adjacent brushes.

 As follows from the foregoing, the proposed device operates with periodic contact of the brushes with the sieve at a time when there is no screening of the material through the holes, i.e. brushes do not interfere with screening. In addition, when exposed to particles by undeformed tufts of hair, the maximum possible pressure force develops. This leads to an increase in screening efficiency.

 The absence of friction of the brushes on the sieve and a significant reduction in the time of their interaction reduces the wear of the working elements of the brushes.

Claims (2)

 1. A method for separating grain materials by size, including feeding the material to the sieve, reciprocating, sieving the fine fraction through the sieve openings, periodically repeated exposure of the sieve cleaner brushes to the grains stuck in its openings, and removal of separation products, characterized in that the trajectories of the reciprocating movement of the sieve give an inclination, the effect of brushes on the grains stuck in the holes of the sieve is carried out while the sieve stops in the lowest position research institutes, giving the brush axes tilt in the direction of inclination of the sieve movement.  2. A device for separating grain materials by size, including sieves equipped with drives with crank mechanisms and mounted in the housing with the possibility of reciprocating movement, sieves and brush sieve cleaners, the hair bundles of which can pass through the sieve openings, characterized in that the sieve is installed with the possibility of movement along an inclined path, brush cleaners are mounted on a carriage mounted in the housing on guides parallel to the sieve plane of the wiper brush they have an inclination towards the inclination of the sieve trajectory, and the brush cleaner drive has a crank mechanism connected to the sieve drive motor and a vertically closed chain spanning two sprockets, one of which is rigidly connected to the ratchet ratchet wheel, one of which closed chain links connected to the sieve cleaner carriage by means of traction with connecting hinges at the ends.

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