Home – Home – Jornals – Fundamental and applied issues of mining 2020 number 1

The paper presents the hydraulic diagrams of the developed universal stand intended for the practical study of designed automation tools, obtaining their output parameters, as well as for adjusting hydraulic fluid flow controllers and analyzing the adequacy of operation of automatic systems designed to regulate the operating modes of drilling machines. The operating principle of the stand is studied in detail and technical characteristics of its main hydraulic devices are presented.

The measuring and computing system consisting of two sensors was deployed to monitor the geomechanical state of the near-fault zones of tectonic faults at horizons + 380 and + 405 at the quarry of the Zarnitsa diamond pipe in 2019. The monitoring was carried out from 02.10.2019 to 28.11.2019. The measurements demonstrated alternating displacements of geoblocks in the near-fault zones up to 3 mm in size, which lead to rock caving along tectonic faults of the side slopes of the quarry.

A procedure of experimental study of the impact device case movement in a borehole has been developed, including the use of “low-frequency” current-vortex) displacement sensors and “high-frequency” (accelerometers) acceleration sensors. After registration, software signal processing was performed, including double integration of accelerations and determination of points of interface of displacements obtained after integration and direct registration. Oscillograms of measurements at different values of reaction from the rock mass are given. The quantitative aspects of the phenomenon are discussed, and an attempt is made to identify the relationship between the quantitative indicators of impact pulses and case displacement.

A simulation model of a one-way self-oscillating hydro-impact system with two limiters of striker movement has been developed. The system includes a pump (a constant flow source), a striker (piston) and body (with limiters) connected by a mechanical spring, a spool distributor, a gas-liquid accumulator, and connecting hydraulic lines. By comparing the results of calculations on the simulation model with the results of calculations on the “ideal” model (without hydraulic and mechanical losses and instantly switching distributor), the developed model was verified. Calculations of the operation modes of reverse hydraulic shock devices with an impact energy of 80 and 160 J were performed, their parameters were determined, and the real geometry of the devices was evaluated. The developed equipment can be used to overcome jamming of equipment during drilling and use of special equipment in already drilled holes, when driving workings by impact method in the ground.

Among various types of resistance of a rock mass to the penetration of a solid body into it, the resistance types associated not with rebound, but with the depth of penetration (viscoplastic resistance) are determined. It is shown how at a known initial speed of the tool movement (at the depth and time of penetration measured in experiments), for a given tool geometry, the required resistance function is restored, consisting of a constant term and a function which depends on the speed of movement. More acceptable is the geometry of the tool, in which the resistance of the medium to penetration for a given depth is minimal.

The operating principle of the impact mechanism with sealing elements and an external switchgear is described. The results of an experimental study of the prototype are presented, indicator diagrams are shown.

The paper presents the results of studying the distribution of air temperature along the length of an extended railway tunnel depending on various configurations and locations of tunnel heating and ventilation units. It is shown that the most rational way is the uniform arrangement of heating and ventilation units along the length of the tunnel combined with the installation of air-thermal curtains. This allows ensuring a positive air temperature in all sections along the length of the tunnel.

Aerodynamic schemes have been developed for highly loaded mining axial fans with an aerodynamic loading coefficient of 696 - 914 kW/m², which is 4 - 5.3 times higher than currently produced mine fans. The result is based on an increase of the blade tip peripheral speed up to 220 m/s. This became possible by solving the topological optimization problem where distribution of the blade material is calculated using minimum weight criterion. This made it possible to create blades with an oriented structure, the weights of which are 50 - 70 % less than the weight of a monolithic blade, provided that the permissible stress-strain state is maintained.

The dynamics of an elastic working body of a transporting device equipped with two inertial vibration exciters was studied experimentally. The nature of change in the mismatch of the rotational frequencies of vibration source rotors and the degree of their mutual influence when increasing the linear weight of bulk material is determined. The basic relationships of the structural and dynamic parameters of the vibrating device are found, which make it possible to increase the transportation range of loose geomaterials.

The article discusses a prototype of a vacuum impact machine. The experience of its use in the implementation of technologies for the exploration of minerals and the development of underground space is shown. The main parameters of the automatic control system of the VIM are experimentally determined. Further ways of automatic control systems modernization for machines of this class are outlined.

A brief overview of the equipment used for driving steel elements into the ground is made. The main parameters of a pneumatic hammer designed for driving pipes with a diameter greater than 1220 mm into the ground with an open end are substantiated. The device and features of operation of pneumatic hammers with a variable structure of impact power, which have an elastic ring valve in the air distribution system, are described. Based on the analysis of long-term operation of equipment for trenchless laying of underground facilities and driving vertical pipes, a forecast is made about possible difficulties in creating a large-sized super-heavy pneumatic shock device. The design principles are proposed, as well as possible ways to solve the problems associated with creating a pneumatic hammer with the impact part weight greater than 1000 kg.