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research of process of hashing of components of a mix on a natural model

Experimental researches were spent with use of bench installation both in laboratory conditions, and in the conditions of operating manufacture. For the purpose of revealing of law of interaction vertical lopastnogo the bulwark of the shower mixer, walls of the chamber and the screw elements fixed on walls of a drum head, with mix components installation-model of the shower mixer with a transparent mixing drum has been made.

Character of process of mixing of components of a mix and loading moving has been removed on a videocamera with the subsequent storyboard with a spacing in one second.

At physical modelling of character of movement of particles of loading the assumption (p. 50, fig. 2.4) was accepted, that at values of district speed of rotation lopastnogo the bulwark of an order of 4-5 km/s the loading material passes in psevdoozhizhennoe a condition which is characterised by formation of a funnel round the vertical bulwark located in the centre of the cylindrical case of the shower mixer that is confirmed by the spent experiments on a natural model (fig. 4.1).

Drawing 4.1. Funnel formation at hashing of various materials in the investigated shower mixer: and - grainy materials;, in - powder materials

For the purpose of definition of character of moving of components of a mix in a shower mixer drum head a series of experiments has been spent:

- Drum head, without the screw surfaces of the blades fixed on it, filled with salt (fig. 4.2,) and salt with sand (fig. 4.2,);

- Drum head, with the screw surfaces of the blades fixed on it, filled with millet (fig. 4.3.), salt with sand (fig. 4.4,) and salt with a dark blue pigment (fig. 4.4.б);

- Drum head, with the screw punched surfaces of the blades fixed on it, filled with salt (fig. 4.4,), salt and a colour pigment (fig. 4.4,), salt with sand and a colour pigment (fig. 4.4,) and millet with rapsom (fig. 4.4,).

The photographing analysis (4.2) has shown fig., that at rotation lopastnogo the vertical bulwark with frequency of 470 mines-1 (fig. 4.2,) and 630 mines-1 (fig. 4.2,) in a mixing drum, without the screw surfaces of blades fixed on it, occurs razbivanie mixes on layers, i.e. obrazovyvajutsja the closed streams of movement of the material, created by blades of the vertical bulwark. Thus blades on the bulwark are turned concerning a vertical on 45 hailstones and located in three ranks. Therefore moving of components to mixes (salt and sand) between layers occurs slowly enough and hardly from a layer in a layer,
That leads to increase in time of mixing and, as consequence, to decrease in quality of a ready product and to increase energopotreblenija.

For destruction of the closed streams of movement of the material, created bulwark blades, on an internal wall of a drum head of the shower mixer had been established under a corner to horizon screw surfaces of blades of a drum head (fig. 4.3).

The photographing analysis has shown, that loading particles at contact to edge of screw surfaces pass from top level on bottom, and further, getting on a screw surface of the bottom level and, sliding on it upwards, again pass to more bottom level if it is.

Otherwise, it is picked up by blades of the vertical bulwark and circulation process repeats. Thus, moving of components of loading between layers that intensifies mixing process is carried out.

Here it is necessary to notice, that the described process concerns mixing of fine materials. At mixing of powder materials (fig. 4.4) is observed occurrence of stagnant working areas around walls of the case and the screw surfaces of blades established on it, since 1/3 their lengths (a dark blue pigment). Nevertheless, under the influence of the centrifugal and elevating forces created by a corner of ascending gradient of a spiral, only the part of particles from a stagnant working area is grasped by a stream of moving particles (rice 4.4,), that finally influences quality of a received mix.

Drawing 4.4. A drum head with screw surfaces of the blades, filled with salt with a dark blue pigment with a corner of installation of a screw surface β =303 (a) and β =45 ° ():

- Formation of stagnant working areas on a screw surface of the blade of a drum head

Drawing 4.5. A drum head with the screw punched surfaces of the blades, filled with salt (and,), salt and a colour pigment (), salt, sand and a colour pigment () and millet with rapsom (): With - prosypanie material particles through apertures in screw

Surfaces

For elimination of the given lack it was offered to execute screw surfaces of blades of a drum head perforirovannnymi. For presentation in experiences on a natural model, on an average part of screw surfaces of blades, have been made on one aperture at a drum head wall (fig. 4.5).

In pictures it is well visible, that thus occurs prosypanie through apertures of particles both powder, and fine materials. Therefore, the decision for labaratornoj installations was accepted to use on an internal wall of a drum head the punched screw surfaces of blades [84].

For definition of time of mixing of components, at performance polnofaktornogo experiment, additional experiences have been spent and the storyboard of process of mixing of grainy materials (fig. 4.6) with a spacing in 1 second (as in experiments the rotating speed lopastnogo the bulwark varied from 470 to 630 mines-1, that there correspond 8-11 turns lopastnogo the bulwark for 1 second) is made.

At initial stages of mixing (1-3 sek), to the established operating mode of the shower mixer (fig. 4.6, a-v), is observed ascending gradient of light particles in pristennoj to a working area and falling of dark particles at the expense of created lopastnym the funnel bulwark, on what specifies their occurrence in pristennoj to the bottom part of a drum head (fig. 4.6, in,). On fig. 4.6 () it is well reflected nabrasyvanie a material by blades of the vertical bulwark on screw surfaces of blades of a drum head and destruction of the closed streams of movement of the mix, created by blades of the rotating bulwark. Thus, mezhslovoe moving of particles is provided with presence of apertures on screw surfaces of blades of a drum head (fig. 4,6, v-i).

Quality of mixing influences also that fact, that blades of the vertical bulwark, grasping a portion of a material, reserve a trace (fig. 4.6 b-r) in the form of empty space which is filled with particles mezhlopastnogo a layer by gravity. The trace arises because of enough big rotating speed lopastnogo the bulwark, and the centrifugal forces, operating on particles of a material which prevail over their gravity that provides psevdoozhizhenie mixes.


π) t=14ce κ p) t=15ce κ

RisunokD.b. Time-lapse shooting of process of mixture of fine materials in a drum head with transparent walls (termination):

C Ξ> - areas nabrasyvanija a material on screw surfaces; - areas prosypanija chastil a material through apertures in screw surfaces: *C  - ■ - area of a trace left blades cotton wool; - congestion areas chastil one sort of a material



On 8-10 seconds of mixing (fig. 4.6, z-m) in pristennoj to a working area areas of a congestion of particles of one colour are observed. Here it is possible to notice, that since 11 seconds of a cycle of mixing the established operating mode of the shower mixer and rather uniform distribution of components of a mix in all volume of a drum head is observed. Thus, it is possible to consider, that on 16 second of a cycle (fig. 4.6,) there is a full mixing of components of a mix.

For definition of optimum time of mixing for powder materials additional experiences have been spent and the storyboard of process of their mixture (fig. 4.7) with a spacing in 1 second is made at 550 turns lopastnogo the bulwark. In a natural model with transparent walls salt, sand and krashennyj a pigment have been backfilled.

At initial stages of mixing (1-5 sek) and to the established operating mode of the shower mixer (fig. 4.7, a-z), is observed ascending gradient of all layers of a material in pristennoj to a working area and creation of dead working areas above and below apertures on a screw surface of blades of a drum head (unlike mixing of fine materials) (fig. 4.7, d,). Well considerably nabrasyvanie a material blades of the vertical bulwark on screw surfaces of blades of a drum head (fig. 4.7., a-d), and, thus, it is possible to notice, that mix components wake up through apertures in screw blades of a drum head (fig. 4.7, d-z), than efficiency of the punched surface of blades of a drum head proves to be true. At increase in live sectional view of screw surfaces of blades of a drum head mixing process is considerably intensified.

As well as in a case with hashing of fine materials, on creation psevdoozhizhennogo a layer influences formations of a trace in the form of empty space (fig. 4.7, to, m-p) which is filled with particles mixed poroshkoobraznyh components from mezhlopastnogo (top) layer on action of a gravity. On 13 second of a cycle (fig. 4.7,) occurs full mixing of components of a mix.

4.2.

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A source: BRAZHNIK JULIA VIKTOROVNA. PERFECTION of the DESIGN And MIXING PROCESS In the AGITATOR MIXER With the HIGH-SPEED OPERATING MODE. The DISSERTATION on competition of a scientific degree of a Cand.Tech.Sci. Belgorod - 2017. 2017

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