Vol 65 Iss. 1

During 1967-1970, the operation of wide- and narrow-capture harvesters was studied at Norilsk mines. During the tests, the average and instantaneous values of power consumption P, current I, feed rate v_n and feed force F_п were measured. Special sensors and recording equipment were made to record these parameters. One of the tasks of the tests was to establish the dependence of the harvester productivity on the extracted power of the formation.

At present mining machines operate with electro-hydraulic feed drive of “Ural-33”, “Ural-37”, G-404 types, technical and dynamic properties of which are studied insufficiently.

Productivity of mining harvesters largely depends on the efficiency of the feed drive, providing the machine movement during operation and maneuvering operations. The complexity of the design, high class of manufacturing accuracy and the need for high reliability, especially when working in mechanized complexes, require a thorough inspection of the feed drive assembly before the machine is lowered into the mine. Such a check can be carried out on test benches. Thus, at the ore-repair plant named after V. I. Lenin. V. I. Lenin ore-repair plant combine “Tulaugol” very carefully tested repaired feed drives G-404.

An important importance in the selection of hydraulic drive for mining machines is the development of more convenient methods of using the characteristics of the hydraulic drive. The main role in the transformation of speeds and torques of the hydraulic drive is assigned to two of its properties: the graphical representation of these two properties on the operational characteristics of hydraulic turbo-transmissions has been called stiffness and opacity.

The dynamic character of the action of a hydraulic monitored jet on a monolithic massif is related to the well-known Bernoulli formula for the pressure force of a stationary jet on the plane of an obstacle perpendicular to it...

In the process of operation of the hydraulic monitor complex, the head at the nozzle of the hydraulic monitor during the shift varies due to the disconnection and connection of consumers of high-pressure hydraulic energy. These head fluctuations affect the performance of the hydromonitor.

Jet devices, or ejectors, are characterized by simplicity of device, reliability and ease of operation. Therefore, despite the relatively low efficiency, they are very widely used in various fields of technology as pumps, compressors, hydroelevators, fans, vacuum pumps.

In calculations of horizontal and working on lifting belt conveyors the value of the preliminary tension of the belt is determined, as a rule, the condition of the absence of slippage of the belt on the drive drum and calculated by the well-known formula...

Studies of the movement along the slurry lines of hydraulic mixtures with different degrees of saturation showed that this process is probabilistic, this is due to the random nature of the distribution of the frequency of pulsations of velocities and the occurrence of turbulent vortices in the flow. With increasing concentration of hydraulic mixture, the suspending capacity of the flow increases, while the intensity of its mechanical impact on the solid component increases, the probability of collision of particles among themselves increases.

Hydraulic transportation of ores is usually accompanied by a change in the particle size distribution of the transported material. This is especially characteristic for transportation of multifractional hydraulic mixtures along complex routes, with a significant difference in the marks of the beginning and end of the line.

In the practice of pipeline hydraulic transportation of bulk materials, the equation of hydraulic resistances of the type...

There are known cases when start-up processes of hydraulic conveying plants were accompanied by accidents. The cause of such accidents is a hydraulic shock arising due to the formation of “plugs” and rupture of flow continuity at the moment of switching on the subsequent stages in schemes with several pumping stations operating in series. “Plugging” in the pipelines occurs, as a rule, at previous stops.

Hydraulic transportation of bulk materials is increasingly used in various sectors of the economy. Numerous studies conducted by various organizations show that the efficiency of hydraulic transport increases with increasing consistency. However, in many cases due to technical and technological conditions it is impossible to obtain flows of high saturation or use thickeners of hydraulic mixtures, as some of them cannot provide high concentration, others due to their design features (large overall dimensions, weight) cannot be used in the system of continuous transport. Therefore, the creation and introduction into production of new types of thickeners is currently of great importance.

If an emergency stop of a mine train is required, the inductor car brakes and the mechanical brakes of the electric locomotive are applied simultaneously. Car inductor brakes act as dampers of the highest initial speed, due to the instantaneous distribution of braking force along the length of the train.

The study of operational reliability of heavy-duty dump trucks BelAZ-540 and BelAZ-548A was carried out in extremely difficult natural and climatic conditions of apatite mine “Tsentralny”, located in the center of Khibiny at an altitude of 1000 m above sea level. Reliability analysis was performed on the basis of data for 1970-1971. Only relatively serious failures of vehicles, which required at least two hours for their elimination (including the time for fault detection, dump truck travel to the repair shop and the time of all operations related to repair), are taken into account, since there is practically no information on smaller failures.

Increase of efficiency of use of dump trucks is impossible without scientifically grounded estimation of their operational qualities, operating conditions and level of organization of technological process. Long experience of operation of heavy-duty dump trucks has shown that the modes of their operation in the conditions of the North sharply differ from the modes of operation at the quarries located in more favorable climatic zones.

In the practice of operation of mining enterprises there are widespread cases when the whole cargo flow from a group of mines to consumers follows through one assembly station. In such a scheme, the total cost of transportation does not depend on the interconnection of consumers and suppliers (at given volumes of production and consumption of individual production units).

In coal pits, the most productive method of blast drilling, in which rocks are destroyed by the principle of cutting, is becoming more and more widespread. The main disadvantage of this principle is the rapid blunting of rock-destroying tools.

Semi hopper storage with slotted outlet is a type of modern automated large-capacity storage. The criterion for selecting the main parameters can be taken as a minimum cost of construction of the warehouse, since the change in the length L and cross-section F of the stack has a relatively small effect on the operating costs.

Characteristics of fans are widely used in the design and operation of ventilation systems of mines and mines. Different interpretations of certain aspects of this issue have not been given much importance until now. However, now, during the transition of industrial enterprises to new principles of economic management and economic incentives, engineers have to find reserves for saving material resources and reducing production costs. At the enterprises more and more importance is attached to the issues of testing of mine fans, at the same time, and there are contradictions in the theory and interpretation of certain issues related to the evaluation of the economic efficiency of mine suction fans of main ventilation.

There is a very extensive literature on diffusers, and in modern scientific and technical sources, much attention is paid to this issue. Most of these studies are related to the development of diffuser designs and are devoted to the determination of the most favorable angle of diffuser opening behind centrifugal and axial fans, pressure losses in diffusers, optimum diffuser length, etc.

Experimental and theoretical studies carried out in LMI to create a two-stage active hydraulic turbine with inclined-jet stages, hydrodynamic scheme of which is shown in the figure, have shown that the characteristics of such turbines fully meet the objectives of turbine drive at hydraulic shafts and have a number of advantages. The most important of them are relatively low specific speed of the two-stage turbo engine, small radial size and characteristic for the engine axial exhaust water discharge. As shown by tests of an experimental sample of such a turbo engine, with the correct setting of design parameters, in its efficiency, it can not yield to the currently used radial and bucket turbo engines.

Analysis of the operating process of the inclined-jet hydraulic turbine on the basis of the Euler equation shows that the hydraulic efficiency of its impeller is expressed by the ratio...

The total heating surface of a mine calorifier is calculated by the maximum heat release required from it Q_tmax(kj/h), calculated by the absolute minimum of the outside air temperature for a given location from the expression...

It is known that at the vast majority of mines and mines located in areas with harsh climate, in winter time part of the atmospheric air supplied to underground workings for their ventilation is heated. To do this at the shafts and adits, where the ventilation jet comes, build, as a rule, steam caloriferous installations with a multi-row arrangement of metal plate calorifiers, the sequential movement of heated air in them provides the necessary air temperature difference...

In the work of L. P. Severin and K. A. Dolgov the formula is given...

The executive tracking mechanism consists of a two-piston servomotor, the pistons of which are connected by a toothed rack that transmits motion to an output roller and a wedge acting on a feedback sensor...

Ya. P. Greenberg believes that calculations of the possible productivity of coal mining machines on their energy characteristics and on the characteristics of the electric motor or specific energy consumption in practice inadmissible, because they do not take into account the variable nature of the load, frequent inclusions of the motor, and recommends to calculate the RMS current of the motor and its characteristics...

Methods of calculating the performance of mining machines, associated with the use of energy characteristic and motor characteristic , have a number of significant disadvantages. Firstly, they do not take into account the significant load irregularity arising from random factors (variability of cutting resistance, feed irregularity, finite number of cutters, etc.). Secondly, the energy characteristic does not provide information for predicting instantaneous values of maximum loads, which may be the cause of motor overturning. Thirdly, it does not take into account the additional heating of the motor during operation with reduced voltage, which is not uncommon in the conditions of district electric networks.