Vol 39 Iss. 1

Transients in a closed single-loop system under certain assumptions can be described by a linear differential equation…

In a mine hoisting machine, the controlled object is the drive motor. The autoregulation system should provide a certain program speed of the machine per lifting cycle with proper transients in the electric drive- According to the structure, the control system of the hoisting electric drive is a scheme with feedback on the motor speed (Fig. 1). Regulator B-P in this scheme performs the functions of an adder of influences: setting program of speed change and regulating influence, transmitted by negative feedback from the output to the input of the system.

Reliability of the braking device is of particular importance in the transfer of lifting systems from manual control to automatic.All domestic lifting machines, having coiling apparatuses with a diameter of 4 m and above, are equipped with a fast-acting pneumatic braking device Novo-Kramatorskiy machine-building plant (NKMP).

Mine air pipelines are called complex when the network is highly branched and has a large number of diverse consumers of compressed air. In contrast to such networks in industry, there are simple networks, when a trunk line of often constant diameter is laid from the generator, through which compressed air energy is supplied to one, two or three homogeneous consumers.

A specific feature of a hoisting system with a friction pulley is the existence of a minimum hoisting height limit, which is provided by the drive pulley under the conditions of rope sliding. The upper limit on the lifting height is determined by the prescribed strength of the ropes. The article presents the main dependences determining the area of use of multi-rope friction pulleys in the range of permissible lifting depths, and also gives a graph-analytical method of calculation of this system for the case of application of equilibrium tail ropes.

Pneumatic motors and tools, widely used in underground work, increase the compressed air consumption if its pressure is increased. Working at higher pressures is associated with more intensive wear of pneumatic equipment and especially rotary pneumatic motors. Automatic pressure regulation directly in front of the consumer could help to eliminate these disadvantages, but produced pressure regulators are bulky, heavy, so it is difficult to use them in underground conditions.

Gear motors are one of the types of pneumatic motors, widely used as a drive for harvesters, cutting machines, conveyors, drilling and assembly machines, winches and other mechanisms in mines, hazardous by gas or dust. Mostly common are motors with oblique teeth, which, in contrast to the spur tooth, have a higher smoothness of meshing and less noise during operation, and in contrast to chevron - greater simplicity of design and ease of reversing. Pnevmatika plant, for example, produces motors with helical rotors: PSHB-30 for the drive of the combine KKP-1; PRSH-10 for the drive of the light gathering-drilling machine LBS-2; PRSH-16K to the winches of the combine KKP-1; PRSH-16M for the drive of the drilling-drilling machine SBM-Zu, conveyor SKR-11, winch OPL-700, etc.

Brief review of the main theories of working processes and methods of calculation of pneumatic hammers. The main purpose of the theory of working processes of pneumatic hammers is to establish the dependence of work and the number of blows of air flow rate on the pressure of compressed air and the structural dimensions of the hammer, as well as on the physical properties of the rock destroyed by the hammer.

A new method of calculating the work of impact and air consumptionThe work of impact. Working processes occurring in the cylinder of pneumatic hammers are mainly characterized by differential equations of ideal gas flow and piston motion (without taking into account the back pressure) ...

The operating mode of traction motors of mine electric locomotives is poorly studied. There is no theoretical justification for the selection of traction engine power to a given locomotive weight. In the USSR and abroad the ratio of engine power to locomotive weight is taken differently by different plants and firms. American companies, for example, for 1 t of locomotive weight take engines with power from 6.95 to 8.76 kWt, West-German - from 4.62 to 6.57 kWt, plants of coal machine building in the USSR - from 5.88 to 6.57 kWt. Thus, American electric locomotives have a higher specific power. Increasing the specific power of an electric locomotive guarantees traction motors from possible overloads. This is a positive factor. If the forces of resistance to the train movement exceed the traction force provided by the coupling weight of the locomotive, the driving wheels will start slipping and there will be no further increase in the power consumed by the engines. At the same time, the automatic limitation of traction motors loading will be provided by the value corresponding to the electric locomotive coupling weight.

The methods of energy consumption determination existing in the practice of underground electrified rolling do not take into account some peculiarities of electric locomotive operation. The survey of coal and oil shale mines in a number of basins has established that when an electric locomotive is operating, the energy is additionally (unproductively) spent on abrasion of wheel bands and rail heads during slipping, in rheostatic resistance and increased losses on heating of engines. This energy consumption is especially high on the complex longitudinal profile of the pumping tracks.

One of the tasks in the implementation of remote control of underground mechanisms is to improve the safety of electrical equipment operation. Accordingly, such a parameter of control circuits as the voltage value should be taken from the condition that, at least, these circuits themselves are not the cause of accidents from electric shock.

In spite of the fact that the dredge method of alluvial deposits development has been used for quite a long time, the available literature on dredging is very poor. The overwhelming part of monographs and journal articles devoted to this issue, as well as related to it - the use of dredges, is descriptive in nature, and only a small part to some extent approaches the issues of the theory of soil cutting.The most important stage in determining the load overcome by the motor of the dredge chain is to establish the value of the total resistance to digging the soil, the causes that cause load fluctuations, and the magnitude of these fluctuations.

In the process of working downhole, the load of the bailer chain drive motors (main drive) of multi-digger excavators and dredges, all other things being equal, is continuously changing. Fluctuations (called natural fluctuations) of the motor load of this drive are the result of variability of the number of scoops in contact with the mined rock and changes in the total resistance to digging along the length of the face. The frequency f of natural load fluctuations is determined by the speed v and the pitch t of the scoop chain ...

Implementation of complex mechanization and automation of mining operations can not be effective without the availability of reliable and economically feasible schemes of power supply of mine electrical receptors. To date, the reliability of circuits has been evaluated based on general considerations and the experience of the designer. Such a subjective decision has often led either to unnecessary redundancy and complication of the scheme, or to a decrease in the reliability of power supply. Generalization of operating experience for the past years with the application of probability theory and mathematical statistics has now allowed to develop scientifically justified methods of reliability assessment and construction of power supply systems of coal mines. The methods proposed by the author are based on the calculation of: 1) the probability of interruption of power supply to mine electrical receptors; 2) the mathematical expectation of losses; 3) the probabilities of accidents due to interruption of power supply to electrical receptors of the first category.

Comparative indicators of transportation cost are the main factors influencing the choice of transportation method. In this regard, it is of great interest to develop the most convenient for practical use methodology for determining these indicators.Determination of the transportation cost indicator for each of the compared options by the method of conventional tabular calculations is a time-consuming and cumbersome process, as it requires preliminary technical calculation of each option and on its basis - the compilation of various estimates and financial calculations.

Transportation of minerals along vertical mine shafts is carried out mainly by skip hoisting. This type of lifting, being an intermittent transportation unit, has a number of disadvantages. The main ones are as follows: 1) the necessity of construction of intermediate tanks (reloading hoppers) in the near-borehole and on the surface, designed to mitigate the unevenness of lifting and transportation on the surface;2) the complexity of full automation of the lifting process due to the need to continuously change the mode of operation of the engine; 3) high specific energy consumption and increased installed power of the engine, caused by the inclusion of starting rheostats and the presence of peak loads at each cycle of lifting.

In connection with the forthcoming development of deep quarries to the rolling stock will be even more insistent two basic requirements: reducing the dead weight of the train and the ability to overcome large gradients. Reducing the tare coefficient of the train about two times and overcoming gradients of about 80-100% in railroad transport can be realized by the usual replacement of locomotive traction by motor cars. However, at these gradients the required number of motor cars is large. This complicates the operation of rolling stock and increases capital and operating costs. For example, according to V. E. Rosenfeld, E. V. Chebotarev and B. G. Kamenetsky, the economic cost of the railroad cars is higher. G. Kamenetsky, the economic feasibility of using motor cars is limited by the slope of only 63%.

When designing a dredge and selecting the main parameters that determine its operation, an important issue is the choice of angular speed of rotation of the motor and the length of the bottom of the scoop. For normal operation of the dredge it is necessary to select these parameters so that the material, pouring out of the scoop, falls into the receiving device. To solve this issue, the movement of material along the bottom of the scoop should be studied.

The principle of tractive force creation by modern locomotives with all its simplicity and perfection has a number of significant drawbacks, which are manifested in the form of slipping of drive wheels during starting, braking and traveling on inclined tracks. This is a consequence of overcoming the variable resistance of the train to movement by friction forces, the ultimate value of which is limited by the constant coupling weight. This contradiction can be eliminated by automatically regulating the pressure of the drive wheels on the rail. Then the drive wheels 1, acting on the rail, located on the levers 2, connected with the locomotive (tractor) body 3 by rods 4 and 5, in the presence of the connecting clamp 6 and rod 7 enveloping the rail head should be pressed to the rail with the force HN, proportional to the resistance of the train to movement .....

Long operating experience and repeated tests of various designs of eccentric parachutes with steel rail conductors have shown unreliability of operation, especially at high fall speeds of the stand.