Tyrtychnyy Sergey

Abstract on a theme of master's work

1. 1.Urgency of a theme of work
2. 2.Goals and objectives
3. 3.Own results
4. 4.Findings
5. 5.References

1. Urgency of a theme of work

The basis of the fuel and energy complex of Ukraine is coal, which has estimated proven reserves of 110 billion tons

The current trend of coal production in Ukraine, as well as in other technologically advanced countries, coal is characterized by ever-increasing intensification of pressure on the lava. Domestic mechanized treatment systems provide a new level of technical ability on the growth of the lava load up to 2 or more tons per day.

One of the factors most limiting the growth of the load on modern mining complexes, is lagging behind in the preparation of a new front treatment works. This problem is really feasible at the sinking of mine workings with the rate of 400-600 m / month.

Such a rate of penetration can be achieved only combine harvester technology of excavation that best meets the requirements of economic efficiency of mining-preparatory work.

At present, more and more widely used in mines in Ukraine and abroad are tunneling machines swept the executive body, equipped with crowns of different configurations.

Made in recent efforts to intensify the passage of mining, as well as further expansion of the scope of roadheaders selective action on the rock faces with enhanced durability and abrasion of rock, cause a significant increase in the loading of the executive body, and in particular its cutting tool.

Resource of the cutting tool roadheaders averages 3-6 working shifts. It is easy to see that the rate of penetration of 400-600 m / month, the daily consumption of cutters can be from 12 to 120 depending on the geological and mining conditions.

With the increase of installed power of machines and use them to destroy a hard coals and rocks, not only increases the specific consumption of the cutting tool, but also changes the structure of faults. This increases the proportion of failures polomochnyh, reaching 50 - 70% of that in 5 - 10 times higher than normal. For many cutters breakdowns occur in the acute condition, which is not achieved because of the operating time due to abrasion tool.

Thus, there is a need to monitor the boundary condition of the cutting tool that would make rational use of resources of the machine to provide the specified performance.

2. Goals and objectives

Goals and objectives are as follows:
• • Determination of the limiting degree of bluntness of the working tool by the performance;
• • Determination of the limiting degree of bluntness of the working tool by resource;
• • Determine how to diagnose the working tool wear roadheader;

3. Own results

Effect of wear of cutters for maximum performance

Question of criteria of wear of cutters were engaged in the authors [1]. Thus, this paper shows the instantaneous contact area (area dull) blade with an array of destructible wear along the length of the tool for different values chip thickness. Effect of wear on the incisors of the cutting force was studied in detail [2] , which was built by interpolation of the dependence of the cutting forces in the destruction of blunt cutters sylvinite layers. At the work [3] conversely the results do not contradict the assumption that pereiznoshennye cutters are able to limit the bluntness for which there is no substantial increase in load.

To determine the forces on the working tool used formula OST (1) ,(2)and the interpolation function (4),(5) obtained from the experiment described in [4] .

where:

Рk – contact rock strength, MPa;

Kt – factor takes into account the type of tool;

Factor Kg calculated by the formula (3):

Kf – coefficients taking into account the shape of the head core cutter;

Kf1 – coefficients taking into account the shape of the tool holder;

Kd – coefficients taking into account the diameter of the core cutter;

Ка – coefficients taking into account the angle of the cutting chisel;

t – width of cut, mm;

h – slice thickness, mm;

S – blunt projection area on a plane cutting.

где:

Ар – the expectation of resistance to cutting, кН/см;

t – width of cut, сm;

h – slice thickness, сm;

S – blunt projection area on a plane cutting;

γ - angle of the blade, degrees.

For the calculation of effort on the executive board was composed mathematical model vektara external perturbation which has the form:

The initial data determine the vector of external disturbances, which is formed in the axial crown fracture of the array is: the destruction of the array parameter vector blade cutters crown ; vector components of cutting forces on the incisors blades ; number of blades on the crown Nз.

With the known value of m (number cutter layer being destroyed), the values components of cutting forces on the incisors are determined by the dependences:

where:

-respectively, a lateral force, feed force and cutting force on the i-th cutting tool blades with n-bits at a position angle of rotation;

- Depending on definitions for the components of the forces of destruction layer of the array destroyed cutter.

- components of the efforts of the destruction of the array, formed on the incisors of the blade, in the coordinate system of the crown in its n-th position of the angle of rotation;

- components of the unit vectors;

- vector of external disturbances acting on the crown (if the n-th position of the angle of rotation) on the efforts of the destruction of an array of cutters blades, which are components of the time component of the resistance and the principal vector of external forces to coordinate crown;

- vector of external disturbances from being destroyed array, acting on the crown in the n-a position;

- average value of the components of the vector of external disturbances acting on the crown of the array being destroyed by one of its turnover;

- coefficients of nonuniformity of the vector components of the external perturbation acting on the crown.

First of all, it was analyzed the influence of site on the effort to blunt chisel formed on it, and the graphs appropriate for the dependency on the formula remains (Figure. 1) and the interpolation function (Figure. 2).

As can be seen from the plots of cutting force and feed increased by a linear relationship with increasing bluntness incisor area. The increase in blunted site of up to 40 leads to an increase in cutting forces and lateral forces in the 10-10.5 times the formula Kostenko N. and 6-7 times in the formula remains the resilience of the breed Ар=7.5кN/сm.

Then there were the values combine the best performance for efficiency of executive bodies with varying degrees of blunt cutters with restrictions on the stable time and effort into the engine cylinders combine feed.

Was constructed plots of peak performance in rock tunneling machines on site at the blunt end cutters (Figure. 3) and (Figure. 4), from which we can say that the blunting site more than 35mm combine the performance drops below the specified terms of reference.

4. Findings

So you can see the serious problem of timely replacement of the working tool, as this procedure is directly associated with providing the required performance. As can be seen from the graphs shown in Figure. 3 and Figure. 4 boundary value of the site blunting the cutting tool providing the necessary technical requirements for the performance of 25-35mm2.

5. References

1. Тон В.В., Баронская Э.И.«Критерии износа резцов очистных комбайнов».
2. Разрушение углей и горных пород: Науч.сообщ./Ин-т горн.дела им. Скачинского А.А.- М.,1988.-80с. [стр.32]
3. Разрушение углей и горных пород: Науч.сообщ./Ин-т горн.дела им. Скачинского А.А.- М.,1988.-80с. [стр.37]
4. Костенко А. П. «Установка рациональных режимов разрушения сильвинитовых пластов барабанными очистными комбайнами» 1992г. Донецк
5. Топорков А.А. «Машинист горных выемочных машин» - М.,Недра, 1991 -334с.
6. Горбатов П.А. , Петрушкин Г.В. , Лысенко Н.М. , Павленко С.В., Косарев В.В. «Горные машины для подземной добычи угля» - Донецк: Норд Компьютер, 2006. -669с.
7. Грабчак Л.Г. , Несмотряев В. И. , Шендеров В. И. , Кузовлев Б. Н. «Горнопроходческие машины и комплексы» - М., Недра, 1990г.

---