Program Complex for Automated Calculation of the Geometry of Impact Units of Machines

Improving the designs of impact mining machines in order to increase the productivity of drilling operations requires calculations of the geometric parameters of impact units. The greatest effect when the impact is applied to the rock is given by an impact pulse corresponding to the resistance forces of the object being destroyed. In turn, the shape and parameters of the impact pulse are determined by the geometry of the colliding bodies. Analytical methods for analyzing dynamic processes in impact systems involve the use of a very complex mathematical apparatus, which does not allow us to quickly solve the problems of engineering design of machines and mechanisms. The authors of this article have developed a numerical method for calculating and analyzing impact pulses generated in the machine system by bodies of any geometric complexity. The reliability of the theoretical approaches is confirmed by the results of a physical experiment. The developed software allows you to quickly and accurately solve the problem of finding and justifying rational geometric parameters of impact nodes of machines.

Designing a shock test system prototype based on a hydroelastic drive

Laboratory shock tests involve the reproduction of simple one-time and repeated pulses of a certain waveform. In practice, such mechanical impacts on an object are implemented at specialized testing equipment ‒ shock systems. A promising direction in the development of shock machines includes the structures that operate on the energy of elastic deformation of the compressed liquid and the shell of the vessel that contains it. Such systems make it possible to improve the versatility, manageability, and accuracy of impact tests. Underlying this study is the use of a hydroelastic drive to design a prototype of the automated electro-hydraulic system for a shock test system. The proposed shock test system prototype makes it possible to expand the functionality of the installations to perform impact tests with a series of pulses, as well as improve manageability and increase the level of automation. The main feature of the proposed structural scheme is that the reconfiguration for a new impact pulse occurs very quickly. Owing to the presence of a driven rotary drum with braking devices, the bench makes it possible to generate a shock pulse repetition frequency of 1‒2 Hz. The constructed mathematical model of the shock machine takes into consideration the inertia of moving masses, the rigidity of the liquid or "one-way" spring of the charging chamber, as well as the influence of dampers on which the test platform rests. The variables in the mathematical model are linked by differential equations describing two periods within a shock system work cycle: charging and pulse generation. The model's practical value is to determine the dynamic characteristics of the test installation, as well as to calculate the required structural and technological parameters. The differential equations describing the movements at the shock machine have been solved in a numerical way. The study results have established the optimal value (in terms of minimizing the overload on an article on the return stroke of the rod) for the damping factor of the braking device, which is 13,000 kg/s. In this setting, the ratio of the amplitude of acceleration on the reverse stroke to the amplitude of effective acceleration during tests is reduced to a minimum of 0.195

Equipment and materials for shock-intermittent cutting

The article considers the shock-intermittent processing method, which is used for cutting blind threads M12x1.5 in nuts made of steel grade X18N9T. Compared to the conventional method, it allows increasing the processing productivity; the durability of the thread taps has increased to 300 holes (with manual thread cutting, the durability of the taps is 100 holes). The method allows mechanizing labor-intensive threading operations. The optimal conditions of processing by this method are determined based on ensuring sufficient strength of the cutting wedge of the tool under repeated loading and, at the same time, creating the most intense impact on the material of the cut layer of the workpiece. The destruction of the processed material on impact most easily occurs at critical deformation rates, which, for instance, equal 60 m/s for corrosion-resistant steel. This leads to an overestimation of the impact pulse values, and consequently, chipping of the cutting edges of the tool. Therefore, for these processing conditions, there is an optimal value of the pulse load transmitted by the spindle to the tool. For threads M10 and M12 with pitches of 1.25 and 1.5 in parts made of steel grades X18N10T, the best results are achieved at loads corresponding to the increment of the dynamic moment of the driven bushing with the tool. At high pulse loads, the durability of the working tool is sharply reduced, and at lower loads, the cutting performance is reduced. One of the positive features of shock-intermittent cutting is the presence of breaks that facilitate the operation of the cutting wedge due to the better penetration of the coolant. Therefore, shockintermittent cutting is carried out at more intensive modes than conventional continuous cutting. However, the tool life does not decrease as a result, but even increases. The relative length of the cutting area, determined by the angle, should be chosen based on the fact that the temperature in the cutting area does not have time to reach its steady value, equal to the cutting temperature during the normal long-duration cutting, carried out continuously.

Non-abrasive Finishing of Mating Surfaces of Machine Parts Using Mixed Techniques with Electromagnetic Fields Application

In various branches of mechanical engineering, faucets, valves, gate valves and other shut-off devices are manufactured and used. Their main purpose is to regulate the flow rate and direction of flows of liquid and gas media. Features of such products in the aerospace and petrochemical engineering are special strict requirements due to the specificity of their operation. These include, for example, high pressure, resistance to aggressive, fire-and explosive environments, leaks of which are unacceptable according to safety rules and environmental legislation. The design of such products, as a rule, assumes high requirements for accuracy and roughness, especially at the interface of parts, high strength in case of impact pulse effects of the fluids in them. To ensure the above characteristics, finishing abrasive treatment is most commonly used, which can result in the effect of impregnation of the surfaces of products, which will negatively affect the useful life and performance indicators of the mating surfaces. At the same time, it is obvious that mechanical finishing without any use of abrasives is extremely difficult and time-consuming. The authors of the article suggest elimination of the negative effect of impregnation by means of mixed machining techniques with the application of electromagnetic fields. Purpose. The purpose of the work is to develop a technology for non-abrasive finishing of machine parts by developing a model that allows selection or calculation of the production modes of gapless mating parts of locking devices applied in various industries. Methods. The method of the research is the use of the scientific basis of mixed machining techniques, the theory of mass transfer in electrical machining, the fundamental foundations of mechanical engineering technology, modern methods for studying characteristics at the final stages of machining, modern measuring tools, special technological equipment, as well as computer technologies. Results. As a result of the research, new technique and devices were developed. This made it possible to implement a non-abrasive finishing operation of the mating surfaces of parts made of metal materials, the processing of which by mechanical methods is difficult. Conclusion. As a result of the conducted research, it became possible to obtain high-quality high-resource gapless locking products and to reduce labor intensity of the finishing operation up to 5 times and preparation for the production up to 2 times.

Dust impact detections by a set of Faraday cups in the lunar environments

<p>The Bright Monitor of the Solar Wind (BMSW) for the Luna-Resurs-1 mission is an instrument designed for high-time (30 ms) resolution measurements of moments of the ion energy distribution by Faraday cups in the solar wind and in a plasma environment at altitudes between 65 and 150 km above the lunar surface. Previous studies performed by a similar instrument located on-board the Spektr-R spacecraft demonstrated a possibility to detect hypervelocity impacts of dust grains by such instruments Our analysis shows that the main problem of the reliable detection of dust impacts using such types of instruments is their sampling rate. In the paper, we present a novel design of a set of FCs that improves the ability of the dust detection using a simple identification algorithm that can store data with a higher sampling rate around the impact pulse. Moreover, we discuss a calibration of the detectors and their front-end electronics using the dust accelerator in order to find a relation between impact parameters and pulse heights.</p>

The study of rolling stock wheels impact on rail switch frogs

Studies of stress distribution across cross sections by polarization-optical method made it possible to propose a relatively simple experimental method of determining contact forces. Experimental determination of contact forces on crossbars of switches is possible by means of sensors located in places of stress concentration (at core base). Analysis of oscillations during impact-pulse loading makes it possible to determine design parameters of the path. Typically, single circuits with four to five degrees of freedom produce quite satisfactory results and may be recommended for the calculated determination of contact forces on the crossbars of the switches.

ASSESSMENT OF STABILITY OF MINING DEPARTMENTS UNDER IMPACT LOADS

Purpose of work. The purpose of the research is to determine the conditions for ensuring the stability of mine workings in the coal massif under the action of shock loads. Methods. To achieve this goal, analytical studies were performed using the basic provisions of classical mechanics and the theory of elasticity. In laboratory studies, experimental samples of crushed rock were used, which were placed in a steel cylinder. Results. In the course of experimental research, the influence of the impact force and the impact pulse of the falling load on the response of the plane on a pliable basis with inhomogeneous, piece-sized, fragmented rock was studied. It is recorded that at a constant amount of energy of a single impact (mgH = 14.7 J), when the height of the fall of the load decreases 3 times (from H = 1.5 m to H = 0.5 m), and the mass increases from m = 1.0 kg to m = 3.0 kg, the magnitude of the impact force is reduced by 50%. With an increase in the amount of energy of a single impact (from mgH = 4.9 J to mgH = 44.1 J) at the same height of fall, when the mass of the load increases threefold, there is an increase of 2.5 times the impact force. At a constant amount of energy of a single impact (mgH = const), the displacement of the plane on a pliable base of crushed rock depends on the magnitude of the impact pulse of the falling load. Novelty. It is proved that when there is collapse of lateral rocks in the coal massif containing the production, the force of impact on the surface is proportional to the time of fall of the rock blocks to the time of their impact interaction with the plane. Practical significance. In deep coal mines, as a result of mining and the probability of shock loads from landslides, to ensure the stability of mine workings in excavation sites, it is advisable to use pliable supports or filling the produced space with crushed rock, which will ensure the integrity of lateral rocks.

Modernization of rock-cutting tool for rotary-percussion drilling that implements eccentric application of impact pulses

Rotary percussion drilling with pneumatic hammers is a promising, high-performance method widely used in the practice of geological exploration, the performance of which is determined mainly by pressure and the amount of cleaning agent supplied by the compressor. The parameters of commercially available high-pressure compressors do not allow drilling at a depth of more than 300 meters, which is one of the main limiting factors of its practical application in production conditions. One of the ways to improve the performance of the rotary-percussion drilling of wells, and at the same time the maximum depth of drilled wells is to improve the mechanism of rock destruction by applying eccentric impact pulses to the drilling tool, which will make it possible to implement more actively the tangential component of the impact pulse that affects the shape and the volumes of the fracture holes being formed, providing additional splitting of the rock in the direction of the rock face. The paper discusses the ways to perfect the known designs of bits for rotary-percussion drilling of wells implementing eccentric application of impact impulses, issues of geometric substantiation of the shape of an eccentric protrusion on a drill bit torus shim for rotary-percussion drilling and oscillations of torus shim when transmitting eccentric impact pulses from the point of view of enhancement durability of a construction and accuracy of transfer of eccentric impact pulses.

Benefits from using two receivers for interpretation of low-strain integrity tests on pipe piles

The double-velocity symmetrical superposition method (DVSSM), which consists of superimposing and averaging two synchronization signals measured at two symmetrical points of the neutral plane of flexural vibration (in an angle of 90°), is proposed to eliminate the high-frequency interference at the pipe pile head without increasing the predominant period of impact pulse. An analytical solution is derived using the transfer matrix method. The calculated responses from the developed solution are compared with the experimental results for different receiving radius angles to evaluate the effectiveness of the developed solution. A parametric study is also conducted to investigate the suitability of the DVSSM. The findings demonstrate that the high-frequency interference is caused by a combination of the flexural behavior of the pile cross section and the wave propagation along the pipe pile head. The flexural vibration mode comprises the primary component of the high-frequency interference, which can be eliminated through the DVSSM without increasing the predominant period of impact pulse. The DVSSM can serve as an efficient method to detect defects near the pile head with much higher detection accuracy than the conventional method.