IMK-14 – Research & Developement in Heavy Machinery 20(2014)2 EN35-38 UDC 621 ISSN 0354-6829

*Corr. Author's Address: Kharkov State Technical University of Civil Engineering and Architecture 61002, Kharkov (Ukraine)

General Classification of Small-Sized Technological Sets for Production of Dry Building Mixtures

Inga. A. Emelyanova 1*, Vladimir V. Blazhko 1

1Kharkov State Technical University of Civil Engineering and Architecture 61002, Kharkov (Ukraine)

The paper presents general classification of small-sized technological sets for production of dry building mixtures. It also presents the results of experimental testing of a new technological set of equipment for preparation of dry

building mixtures. Keywords: Technological sets, building mixtures, mixer, small-size set

0. INTRODUCTION

The increased consumption of dry building mixtures makes the manufacturers of equipment, i.e. factories for production of these mixtures to appear in the market with their new accomplishments and solutions that

provide a high quality and reliability of their mechanical equipment.

A lot of manufacturing companies have recently been dealing with the problem of utilization of technological sets for the production of dry building mixtures. They use a wide range of technological sets and mini plants.

Fig. 1. General classification of technological sets of small size equipment for production of dry building mixtures

IMK-14 – Research&Development in Heavy Machinery

Inga. A. Emelyanova, Vladimir V. Blazhko

Thus, what should be taken into account is the current importance of the mentioned problems as well as the fact that the equipment sets which allow a general classification of such equipment and therefore an illustration of their overview are already used. (Figure 1).

Taking into account the demand for equipment for preparation of dry building mixtures at the Department of Mechanization of the Harkow State Univeristy of Civil Engineering and Architecture, the mini sets shown in Figs. 2, 3 and 4, which cover the mixers mentioned in the previous classification have been designed and

implemented in manufacturing.The main characteristics of operation of the presented sets are their capability to prepare different building mixtures directly on the site. Preparation of a quality (homogeneous) building mixtures is provided by the mixers of new generation. They operate in a cascade regime. Thanks to the simultaneous use of gravitational and forced mixing of components of the mixture, these machines show good results in preparation of building mixture for various purposes (Figs. 2 and 3, position 1).

Fig. 2. Principle scheme of the technological set of small-sized equipment for preparation of fine grain fibro

concrete mixture 1. – mixer with three shafts, 2. – automatic part – asphalt fiber, 3. – bunker components of building mixture, 4. – cell dosers, 5. – mixer frame

2

1

2

1

Fig. 3. Technological set of the equipment for preparation of building mixture for various purposes, 1. – mixer of a gravitational-forced type 2. – strip-like scraping doser

The cascade principle of mixing means that in rotation of the working bodies the mixture components are raised to the upper part of the working space of the machine, where mixture particles, under the action of gravitational force, fall off them and again onto the rotating vanes of the machine. The process of their motion repeats itself and provides motion of the particles in the working space of the mixer between the left and right sides of the wall along a complex path [1].

A mini set with a new way of mixing patented in Ukraine has recently been developed [2] (Figure 4).

The mixer (Figure 5) operates in the following way. The previously dosed components of the building mixture are put, through the loading pipes 2 and 3, into the casing 1 and fall into the zone of action of the rotor with vanes 13 and 14. Thanks to the rotor rotation in opposite directions with a different number of revolutions n1 = 300 min-1, n2 = 200 min-1, as well as to the angle of vane arrangement β = 55 ... 60º, the mixture particles are mixed in a more intense way due to radial and axial velocities.

Radial and axial velocities cause axial pressure, which increases the forces of gravity and friction with the casing walls.Under the action of the rotary shaft with vanes, the mixture components are transferred to a mixed state and directed to the axial direction toward a narrowed part of the left and right cones. By transferring to the narrow space of the casing, two opposite flows pass by each other and fall into two opposite parts of the casing.

IMK-14 – Research&Development in Heavy Machinery

General Classification of Small-Sized Technological Sets for Production of Dry Building Mixtures

Fig. 4. Technological set of the equipment for the production of dry building mixture with the use of a birotor turbulent mixer, 1. – bunker with sand; 2. – bunker with lime; 3. – bunker with dross; 4. – cement silo; 5. – lime doser; 6. – sand

doser; 7. – dross doser; 8. – doser for adding cement; 9. – cement doser; 10. – asphalt fibre; 11. – birotor turbulent mixer; 12. – loading machine.

Final mixing of the mixture components arise due

to the multiple transfer of mixture components to the right and left parts of the casing and vice versa from one flow to the other, which speeds up the mixing process.

The effectiveness of operation of the new set of equipment has been tested experimentally according to the factorial design of the experiment.

Fig. 5. Birotor turbulent mixer, 1. casing; 2, 3. openings for loading; 4, 5 openings for discharging; 6,7. covers; 8, 9.

pneumatic cylinders; 10. flanges; 11, 12. shafts; 13,14. rotors with vanes; 15, 16. electromotors; 17, 18. belt drives; 19. control block.

IMK-14 – Research&Development in Heavy Machinery

Inga. A. Emelyanova, Vladimir V. Blazhko

Fig. 6. Derived solution of birotor turbulent mixer

The main function is the homogeneity of the

prepared dry building mixture– Y1. In the process of experimental operation of the mixer, the indicators of homogeneity of mixture and its control mould compressive strength have been evaluated.

The factors influencing the effective operation of the mixer are as follows: Х1 – the number of revolutions of the working bodies n, revs/min; Х2 – the time of mixing of components t, sec; Х3 – the coefficients of filling of the mixer volume К3, %.

The processed results of exeperimental data and their graphical dependence confirm the efficiency of using the turbulent mixer for preparation of a dry building mixture:

Fig. 7. Graphical dependence of the homogeneity of

mixture on the influential factors

Graphs 1 and 2 show that the increase in the number of revolutions of the working body and the time for production of the mixture have a positive effect on the mixture homogeneity. The effect of the increased number of revolutions can be explained by the increase in the velocity of circulation of mixture particles and their propagation in the longitudinal direction from one zone of the mixer into the other.

By analyzing the data from graph 2 it can be noticed that the quality of mixture (f -5 ... 7%) can be obtained after 25-30 seconds. The increased coefficient of volume occupancy of the mixer casing negatively influences the degree of mixture homogeneity. For the presented structure of the mixer, the recommended value of the coefficient of casing volume occupancy is within the range Кз = 37-45%.

The recommended number of revolutions of the shaft is n1= n2 =120-180 min-1. The character of the curves presented in Figure 6 shows a significant infleunce of the selected factors on the quality of operation of the mixer.

1.CONCLUSION

The paper presents general classification of small-

sized sets of equipment for preparation of dry building mixtures.

The results of preliminary experimental testing of the new model of mixing by forced action confirms the efficiency of utilizing these machines as a part of the technological set for preparation of dry building mixtures.

In accordance with the presented graphs 1-2 (Figure 6), the mixer can be recommended for preparation of quality dry building mixtures in small-sized sets of technological equipment.

2.REFERENCES

[1] И. А. Емельянова, А. И. Анищенко, С.M. Евель, В. В. Блажко, О. В. Доброходова, Н.А. Меленцов, Mixers Operating in Cascade Regime, Monograph /– Kharkov: Team Publish Group, 2012 (in Russian)

[2] И. А. Емельянова, А. И. Анищенко, Mixers of Gravitational-Forced Action Operating in Cascade Regime of High Efficiency Machines, Scientific-Production Periodical Journal Science in Central Russia, 2012 – № 1. – pp. 76-81 (in Russian)

[3] И. А. Емельянова, А. И. Анищенко, В. В. Блажко, Determination of the Trajectory of Motion of Concrete Particles after Falling from the Vane of a Rotary Shaft in a Mixer with Forced and Gravitational Action, Scientific Bulletin of Civil Engineering,– Harkow: HDTUBA, HOTV ABU, 2009. – Vol. 51. – pp. 258-262. (in Ukrainian)

[4] Inga A. Emelyanova, Vladimir V. Blazko, Аnа I. Аnishtеnkо, Оlgа V. Dоbrоhоdоvа, Analysis of the Operation of Concrete Mixer with Gravitational and Forced Action, IMK-14 – Research & Developement Vol. 18 No. 1 (2012)