Introduction

            Purposes and problems

            Topicality and scientific novelty of the topic

            Basic maintenance

                        Determination coefficient of strength (resistance) of mountain breeds

                        Acoustic parameters of mountain breeds

            Conclusion

            Literature list

 

INTRODUCTION

            The coal industry of Ukraine is basis of the fuel and energy complex and the main coal-mining region of the country is Donbass. Coal is used in metallurgy, chemical industry and for municipal needs.

            In the transition to a market economy requires stability of the coal industry and coal production capacity. It will be promoted by working conditions improvement of miners, increases of productivity and machine time of a coal-mining complex, decrease in the cost price of finished products, and also improvement the quality of coal.

Purposes and problems:

            The major problem of the coal industry is modernisation and reconstruction mines of Donbass on basis of the advanced technics and technology of a coal mining. For these purposes is necessary re-equipment of coal mines; development and production of machines for complex mechanization of the cleaning works and mines, ensuring growth in production mainly due to increases in productivity.

Purpose of the diploma:

            Creation of electronic system of a determination the resistance coefficient of coal to cutting and optimal control of a coal combine.

Problem statement:

            Develop an electronic system of a determination the resistance coefficient of coal to cutting and depending on value of factor to regulate the speed of a coal combine.

Topicality and scientific novelty of the topic:

            At present delivery rate of coal combines, in almost all cases, is controlled manually. To increase productivity, and machine time of a coal-mining complex it is necessary to consider factor variability for resistibility of a coal layer to cutting. Currently specialised services of mines carry out measurements of heterogeneity sites for coal layer with the subsequent calculation of factor of resistibility. Based on these data sets range the speed of a coal-mining combine. In a case if the cutting tool will come across firm breed and its speed of giving will not be changed, it will quickly wear out. Last circumstance is especially undesirable in connection with convergence of mountain breeds. Therefore the problem of heterogeneity definition for coal layer in real time is rather actual as will allow to reduce speed of a coal combine only if necessary, and limits of change the speeds to establish according to current calculations.

Figure 1 – Coal-plow machine Kuzbass 500U

 

BASIC MAINTENANCE

Determination coefficient of strength (resistance) of mountain breeds:

            Protodyakonov scale - scale strength coefficient of mountain breeds. This scale designed in the early XX century. Is one of the first classifications of breeds, is based on measurement of labour input on their destruction at getting.

Table 1 - Strength coefficient f on the M.M. Protodyakonov scale

Category	Strength degree	Breed	f
I	Extremely strong breeds	The strongest, dense both viscous quartzites and basalts.	20
II	Very strong breeds	Quartz porphyry, very strong granite, siliceous slate, less strong rather than specified above quartzites. The strongest sandstones and limestones.	15
III	Strong breeds	Granite (dense). Very strong sandstones and limestones. Quartz ore veins. A strong conglomerate. Very strong iron ores.	10
IIІ (а)	The same	Limestones (strong). A rather weak granite. Strong sandstones. Strong marble, dolomite. Ordinary sandstone.	8
IV	Strong enough breeds	Iron ores. Sandy slates.	6
IV (a)	The same	Slate sandstone.	5
V	Average breeds	Strong clay slate. Rather weak clay slate and limestone, a soft conglomerate.	4
V (a)	The same	Various slates (rather weak). A dense marl.	3
VI	Soft enough breeds	Soft slate, very soft limestone, chalk, stone salt, gypsum. Frozen ground: anthracite. Ordinary marl. The destroyed sandstone, cemented pebbles and cartilage, rocky soil.	2
VI (a)	The same	Strong coal.	1,5

            The strength coefficient of mountain breeds calculated by the formula:

fkr = 0.1σsg (1),

Where σsg - uniaxial compressive strength (MPa).

           

Figure 2 – Мethod of determining the resistance coefficient of coal to cutting

(Animation: 100Kb, 18 frames, 7 cycles, to start refresh page)

           

Figure 3 – Density distribution of time resistance of uniaxial compression of containing breeds the coal seams in Donbass (Ukraine)

            Dependence of resistibility to cutting coal Ar from contact durability of breed rk has been received: Ar = 1,79rk. Also it was used resulted in [7] correlation dependence of time resistance uniaxial to compression from contact durability:

σsg = 6,3(rk/9,8)0,6 (2)

            By means of these dependences the distribution law of probability contact durability for destroyed breed has been received:

 (3)

where f1, f2 - the distribution function of the resistance probability to cutting and a temporary resistance to uniaxial compression, respectively.

            Figure 4 illustrates the alignment of cutting resistance for contact strength of specific energy (line 1) and alignment of the probability distribution functions (line 2) to a single function (3).

Figure 4 – Probability distribution function of the coal strength and mountain breeds, given to a single function

            Analysis of the present probability distribution functions suggests that, in the Donbass (Ukraine), the minimum strength of the contact 20-50 MPa, the maximum - up to 1300-1400 MPa, a very large proportion of the weaker species: about 50% of mountain breeds has a contact resistance up to 300 MPa.

 

Acoustic parameters of mountain breeds:

            The acoustic parameters of mountain breeds depend on the physical and mechanical properties, porosity, structure, status, temperature and other internal and external factors. The attenuation factor of an acoustic wave increases with growth of frequency because of dispersion on crystals, however accurate functional dependence is not established. Basically, a linear dependence for the granites in the frequency range 10-1000 kHz - quadratic. The attenuation factor is equal in sedimentary breeds 1,3-2 м⁻¹ for cross-section waves, it in 1,1-2 times is more than attenuation factor for longitudinal waves, but at wet clay and water-bearing sands this distinction can reach 5 and more times as in a liquid shift waves do not extend. Attenuation of elastic waves restricts the basis of control, but contributes to the provision of acoustic signals only those that resonate with the lateral and flat-parallel structures of an array. In an acoustic wave guide it is possible to bring a lot of resonant modes, with wavelength than the number n.

λ = λkr = vn/2a, (4)

In order to eliminate the ambiguity should be borne in mind:

• That the flat-parallel layer of breeds acted as an acoustic wave, the base of listening should be not less thickness of a layer;

• With increase in base of listening in the amplitudes relation of the higher fashions to amplitude of the first fashion decrease;

• With decreasing upper frequency range of measurement extends the range of possible listening bases within which recorded only the first normal mode resonance oscillation, and its boundaries are shifting in the direction of increasing absolute value.

            For example, when listen concrete structures with the use of low-frequency filter with frequency 4 KHz the first fashion of normal resonant fluctuations is registered for plates by thickness not less than 0,5 m, the second fashion - for plates in the thickness not less than 1 m (fig. 5, figures designate numbers of fashions). Thus, the peak for spectral density of normal waves on frequency 4 KHz at listening base to 1 m unequivocally corresponds to the first fashion.

             

Figure 5 – Zone acoustic sound of normal resonance modes using octave filter low frequencies for flat-parallel structures of various materials (cut-off frequencies of filters are indicated by horizontal solid lines): a) concrete, b) argillit c) gypsum, d) iron

 

CONCLUSION

            Determination the resistance coefficient of coal to cutting, hence the optimal speed of the combine will increase the productivity, safety of job for coal mining complex. Also, it will make a significant contribution to the development of automated systems for coal mining.

The graduate work is currently under development. The work termination is planned in December, 2009

 

LITERATURE LIST

1. Glushko V.T., Yamshikov V.S., Yalanskii А.А. Geophysical control in mines and tunnels. – М.: Nedra, 1987. – 278 с.

2. Technique, an estimation and classification of characteristics demolition of coal layers in SSSR.. Part 1. – М.: IGD name А.А. Skochinskogo, 1978. – 47 с.

3. Koshelev K.V., Petrenko U.А., Novikov А.О. Protection and repair of mining. – М.: Nedra, 1990. – 218 с.

4. Semenchenko А.K., Hicenko N.V. Evaluating the effectiveness of ways of regulating the load on the drive in coal-plow machine P110 in the conditions of Donbass – 2004. – № 2 – С. 109–115.

5. OST 12.44.258 – 84. Coal-plow machine of cleaning. The choice of parameters and calculation of cutting forces. Methods. – М., 1985. – 107 с.

6. OST 12.44.197 – 81. Coal-plow machine with arrowy executive body. The calculation of the operational loading of transmission. Methods. – М., 1981. – 48 с.

7. Baron L.I., Glatman L.B., Gubenkov E.K. Demolition of mountain breeds through coal-plow machines. – М.: Science, 1968. – 218 с.

8. Semenchenko А.K., Semenchenko D.A., Hicenko N.V., Shabaev О.Е. – «Development of prospects coal-plow machines».

9. Vinogradova М.B., Rudenko О.V., Suhorukov А.P. Theory of wave. – М.: Science., 1990. – 432 с.

10. Vasiuchkov U.F. Mining. – М.: Nedra, 1990.

11. Yackig V.G., Spector L.A., Kucheryavii А.G. Mining machines and complexes – М.: Nedra, 1984.

12. A.K. Porcevskii. Underground development of coal deposits. – М.: Manual on a course of lectures for students, 1998 г.

 

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© DonNTU, Tereschenko Aleksey Sergeevich, 2009