Rational Parameters Research Articles

Model of the optimal composition of the main technical facilities of a container transport and technological system

To solve the problem of determining the rational type and parameters of containers, as well as the structure of their fleet for the delivery of cargo (cargo), taking into account whether the accepted type and structure of the container fleet corresponds to the values of the required (custom) batches for the delivery of products and the possibility of making appropriate adjustments to the container payload values, an economic and mathematical model of the optimal composition of the technical complex of a container transport and technological system has been developed.

Математическая модель очистки кожного покрова коров для повышения интенсивности теплового обмена при тепловых стрессах

Automatic brushing devices that improve the sanitary-hygienic condition of animal skin and create comfortable conditions are becoming widespread in modern dairy farms. To verify the developed mathematical model of cow skin cleaning, the authors carried out experimental studies on ten animals on a dairy farm. On the lateral surface of each animal three zones with the area of 10×10 cm2 were selected: the first area was not cleaned; the second area was cleaned “dry” with a brush; the third area was subjected to “wet” cleaning with a brush and detergent (soap solution). The temperature of the skin areas was determined for 15 minutes by the non-contact method using a pyrometer. The study results confirmed the effect of skin cleaning on the intensity of animal heat exchange due to increased convection and evaporation under heat stress. It was found that wet cleaning is the most effective method, when the skin temperature decreases by 4.1°C due to the increase in heat transfer by evaporation, while after dry cleaning it is 0.7°C. The developed mathematical model of cow skin cleaning establishes the relationship between the parameters of the brush bristle impact on the contaminated skin surface, the brush device and cleaning modes. The received dependences determine technical requirements and rational design and mode parameters of the brushing device to develop an automatic station of cow skin cleaning on farms.

Computer modeling of the process of siphon casting of a large metal cylindrical ingot

Electroslag remelting is one of the main ways to obtain high-quality large ingots from special steels and alloys, and in particular for the needs of power engineering. Casting in a mold is the most common way to obtain large-sized consumable electrodes for electroslag remelting. Computer modeling was carried out to determine the rational parameters of the process of casting large cylindrical ingots by the uphill casting. This paper presents the simulation results of the movement of liquid metal flows during the filling of a mold with liquid metal and the process of forming a crust of solid metal at that time under the conditions of the uphill casting of a round steel ingot with a diameter of 1 m with a height-to-diameter ratio of 6.5 and a mass of about 40 tons. Analysis of the results of computer simulation shows that in the bath of liquid metal in the mold there is a non-stationary hydrodynamic picture, which changes as the internal volume of the caster is filled with liquid metal. Solidification of the metal begins already at the initial stage of filling the mold. However, under the influence of liquid metal flows, the formation of a crust of solidified metal occurs unevenly due to the uneven distribution of the heat flow from the liquid-metal bath around the perimeter and height of the mold wall, which creates conditions for the hot surface cracks occurrence. To prevent the formation of surface defects, it is recommended to take measures to stabilize the upward flow of liquid metal. The effect of mold preheating on the intensity of metal solidification during the filling of the mold with liquid metal was also investigated. Preheating reduces the amount of solid phase formed during the filling of the mold with liquid metal. The most significant inhibition of the formation of a solid phase with a decrease in the solidified metal volume fraction of 40 % is observed under the condition of preheating the mold wall to at least 550–600 °C.

РАЦІОНАЛЬНІ ПАРАМЕТРИ КРІПЛЕННЯ ПОЛЬОВИХ ПІДГОТОВЧИХ ВИРОБОК У ЗОНАХ ВПЛИВУ ОЧИСНИХ КАМЕР

Purpose. To develop a methodology for calculating the rational parameters for walling development waies, taking into account changes in the stress state of the massif in the unloading zones of the drawn stopes of the first and second stages of mining. Methodology. To determine the patterns of stress distribution around the fringedrifts of the lying and hanging walls, located at different distances from the contact of the host rocks with the ore deposit, an integrated approach was used, including the analysis and generalization of previous studies, analytical studies of the stress-strain state of the rock mass around development waies, using the energy method and statistical data processing. Results. Studies of changes in the stability of walling development waies in the zones of influence of drawn stopes of the first and second stages of mining made it possible to establish that the stability of fringedrifts is influenced by radial stresses that arise around the drawn stopes. This necessitates taking into account the nature and degree of tension of the rock mass in the zone of unloading drawn stopes, in the process of choosing the type of support for preparatory fringedrifts, the service life of which is equal to the time of mining ore reserves in the level. At the same time, empirical formulas for calculating the magnitude of destruction of a rock mass in the roof of fringedrifts of the lying and hanging walls were obtained. On the basis of which a method for calculating the parameters of the roof bolting of walling development waies has been developed. Scientific novelty. The dependences of the magnitude of the destruction of the rock mass in the roof of the fringedrifts of the hanging and lying walls, depending on the distance to the contour of the ore deposit, the depth of the fringedrifts, and the uniaxial compression strength of the rocks, have been established. Practical implication. A method has been developed for calculating the parameters of the roof bolting of development waies, taking into account the change in the stress state of the array of drawn stopes of the first and second stages of mining. Keywords: iron ore, development way, rock pressure, roof bolting, stress-strain state, drawn stope.

Rational parameters of drilling-and-blasting operations for rise working

Rational parameters of drilling-and-blasting operations for rise working

Обґрунтування конструктивно-технологічних параметрів стрічково-гвинтового змішувача сипких кормів

The purpose of the work was to substantiate the operational parameters of the belt-screw mixer of bulk feed on the basis of experimental studies of the process. As a result of experimental studies of the process of mixing loose feed with an experimental mixer, the following was established. With increasing time and rotation frequency, the homogeneity of the mixture increases and reaches a maximum of 97.8% at n = 48 min-1 and t = 3.2 min. after which there is a slight decrease. The nature of the process is close to the typical kinetics of mixing loose materials. The energy consumption for the process is non-linear in nature, while the optimum (the smallest value) is located at the point corresponding to the value of the rotation frequency of 40.5 min-1, and not at the minimum n. At minimum k, energy consumption for the process is 2.25 kW/cycle, and at maximum – 3.66 kW/cycle. The mixing time will be different for different contents of the smallest component and is within 2.9–3.56 min. Based on the obtained data, the rational parameters of the mixer under development were established.

Дослідження кінематичних параметрів вібраційного лемеша картоплекопача з використанням комп’ютерної програми

Statistical data show that a significant share of potatoes is grown in subsidiary farms in Ukraine, so there is a need for small-sized, efficient equipment. The level of agricultural culture directly depends on the degree of mechanization of small farms. The purpose of the work is to improve the design of a small-sized potato harvester while increasing the efficiency of its ploughshare. A new design of a vibrating ploughshare in the design of a small-sized potato digger is proposed, which differs from typical designs in that the crank is made in the form of a disk, in which a groove is made in the radial direction. The connecting rod connecting hinge is fixed in the groove at a given distance from the axis of rotation. This provides an opportunity to set the required crank size for driving the ploughshare. In addition, this type of diggers has the problem of significant vibrations. Therefore, the crank disk has concentrically made holes for fixing the counterweight for partial balancing. Another difference of the vibrating ploughshare is that the cutting blade with rod extensions that is secured on two pairs of hinge suspensions. The front hangers have a certain length and are hinged to the cutting blade. Rear pair of hinge suspensions has made adjusting holes in middle part for connection to frame. These suspensions are connected to each other by a crossbar in a rigid frame, in the middle of which is fixed a bracket with holes for connection with a crank. Such a ploughshare will make it easier to penetrate the soil, better self-cleaning, create a directed movement of the soil mass with potatoes and carry out primary separation more intensively. The kinematic movements of such a vibrating ploughshare are described using the method of closed vector contours, and the numerical implementation of the mathematical model is done using the author's computer program. Thus, the new design of the vibrating ploughshare of the potato digger can provide the necessary regulation in order to change the digging amplitude, create a directional movement of the soil and potato mass and increase the efficiency of separation, as well as the possibility of partial balancing of the dynamic system when using a counterweight. The kinematic parameters of the formed multipurpose mechanism are described by equations based on the method of closed vector contours. For the numerical implementation of the results and their visualization, as well as the determination of the rational parameters of the proposed mechanism, a special computer program has been developed, which enables the researcher to perform a search in an automated mode.

Experimental studies of pruning the haulm of chicory root tops

Chicory roots are a valuable technical and strategically important crop for the leading sectors of the Ukrainian economy. The processing of raw materials from chicory roots allows to obtain energy (biofuel), food (coffee) and pharmaceutical (inulin) products. The low level of mechanization of harvesting chicory root crops (significant losses, damage) does not allow to meet the needs of raw materials for its processing. The purpose of the study is to increase the quality indicators of the cutting of burdock from the heads of root crops by substantiating the rational parameters of the working organs of the improved trimmer. According to the results of field experimental studies, regression equations were obtained that describe the functional change in the number of chicory root crops that have fallen from the ground and the number of damaged root crops depending on the speed of the copier, the stiffness coefficient of the spring of the vertical thrust of the copier and the angle of installation of the copier relative to the horizon. The following values of the rational parameters of the trimmer were obtained: speed of movement of the trimmer 1.6...1.8 m/s; the weight of the moving parts of the cutter is 6...7 kg; the angle of installation of the copier relative to the horizontal plane is 30...35 degrees, the stiffness coefficient of the spring of the copier's vertical thrust cup is up to 45 N/m.

Influencing engagement angle on power parameters in flat-belt gears

The article considers the ratio of forces in belt drives, proposes a calculation scheme for the forces of a flat-belt transmission [FBR], and calculates and analyzes the effect of changing the engagement angle and load on the friction coefficient. Belt drives refer to mechanical friction transmissions with a flexible connection and are used if it is necessary to transfer the load between shafts located at considerable distances. The influence of a change in the coefficient of friction of the belt on the power parameters of the transmission is considered. The load is given in the form of a torque, which is transmitted to the belts by the circumferential force, the tension of the leading branch increases the circumferential force, and that of the driven branch decreases. Power graphs were built, and the analysis shows that the growth of α hurts the friction coefficient f. The curves have their own regularity with the value of the approximation R2. The influence of the change in the angle of engagement a on the coefficient of friction f with a change in load in the form of belt tensions F1 and F2 or F1 − F2 = Ft is considered. Combining these components, it will be possible to calculate and select rational parameters of belt drives; the maximum increase in the friction coefficient, considering the loads on the shaft and supports, allows transmitting torque with a relatively smaller angle α.

Substantiation of rational parameters of open-pit development of a two-layer deposit

Substantiation of rational parameters of open-pit development of a two-layer deposit

RESEARCH OF A COMBINED HEAT SUPPLY SYSTEM WITH ALTERNATIVE ENERGY SOURCES

The configuration of an energy-efficient combined heat supply system of the educational building of the Odessа Polytechnic National University with alternative energy sources is proposed. An experimental database of wind speed, which is tied to the dislocation of the combined heat supply system, was obtained. The averaged data on the wind speed of the Odesa weather site during the heating period have been adjusted. The conditions for using the energy potential of the wind to create a combined system are considered. A calculation model was obtained for the integral repeatability of the wind speed according to the Weibull probability distribution for the heating period. On the basis of the developed mathematical model of the dynamics of thermal processes of the elements of the combined system and the model of the energy potential of the wind, the modes of operation of the heat supply system when the temperature of the outside air changes are investigated. With the application of a mathematical model of the heating system, the optimal daily schedule of the intermittent operation of the heating system in terms of energy efficiency is given. The optimal schedules of the electrical and thermal load of the elements of the combined heat supply system in the intermittent heating mode have been worked out. Daily schedules of charge-discharge modes of the water heat accumulator and the electric accumulator battery have been developed, which ensure optimal loading of the system elements. The evaluation of the effectiveness of the substitution coefficient at a change in the outside air temperature from 5 to –15 °С was carried out. The energy balances of the combined system were studied in order to substantiate the rational parameters of its elements and the system as a whole. The possibility of creating a highly efficient autonomous heating system based on modern energy technologies using alternative energy sources and taking into account their local potential has been confirmed.

Calculation of the strength of multilayer floor slabs supported on three sides

The article considers the calculation of the ultimate rupture load of multilayer floor slabs supported on three sides (two short and one long). The calculation is carried out taking into account three fracture schemes: the first scheme consists of three main destructive cracks that converge at one point, forming an "envelope"; the second scheme consists of two main inclined cracks passing from the corners towards the non-supported side and not converging on the plate field; the third scheme consists of a horizontal crack forming trapezoid in combination with angular cracks, which is the case when testing prototypes. The reduction of a three-layer section to a single-layer section is carried out according to the elasticity modules of the concretes that make up the section. The value of the rupture load is determined from the condition of equilibrium of external and internal forces. The results of the VAT analysis of multilayer reinforced concrete structures according to the proposed schemes were carried out by the authors on the basis of static tests of prototypes of flat reinforced concrete three-layer slabs. The obtained research results allow us to determine rational parameters for the design of multilayer slab structures with reinforced concrete layers of various strength.

Analysis of the functional state of flanged joints

This article discusses related aspects of the formation and provision of the functional quality of the load-bearing elements of frame systems. The subject of the study is the analysis of the state of steel structures with the possible manifestation of violations of the shape of structural elements in flanged joints. The formation and provision of the functional qualities of metal structures and their connections is carried out at all main stages of the life cycle. The scientific hypothesis consists in the assumption that the analysis of the parameters of the stress-strain state in metal structures, characterized by the presence of deviations from the established indicators of functional quality, contributes to an accurate assessment of the parameters of the state and service life. The conditions and circumstances characterizing the possibility of loss of functional qualities of flanged joints of steel structures are determined. A block diagram of the analysis of risks associated with manifestations of the shrinkage distortion of flanges, which reduce the operational reliability of steel structures, has been developed. It is advisable to supplement the methodological basis for the development of design solutions for steel structure units with a forecast (modeling) of the state and operational suitability of a flange connection in the presence of shrinkage distortion of flanges. The results of the analysis of possible states of loss of bearing capacity using a predictive model will contribute to the development of rational parameters of labor intensity and material consumption of manufacturing flanges of steel structures.

On the issue of substantiation of the mathematical model of the process of preparation of mixtures of protein-vitamin-mineral feed additives

The process of preparing feed mixtures using additives is a biotechnical system with deterministic relationships with technological and technical and economic characteristics, and a group of input, disturbing, control and output factors, taking into account which it is necessary to determine the rational machine technology, the structure of operations and the corresponding technical solutions that are embedded in the design of the unit. To describe the processes of mixing compound feeds, the main attention is paid to the analysis of energy parameters, the establishment by experimental means of rational parameters and modes of operation of mixers of different types, the determination of the speed of the product movement in the mixer, its performance and evaluation of the quality of mixing. The development of a general theory of the choice of rational modes and design features of mixers is carried out by compiling a system of equations that describes the functional behavior of individual elements, as well as the influence of connections with external factors imposed on their functioning.

Simulation of the testing process of reciprocating hydraulic cylinders with energy recovery

One of the most important problems of modern mechanical engineering is the energy efficiency of technological equipment and manufactured products. A separate issue in this series is the technology and means of testing finished product samples, including hydraulic cylinders, which can be carried out with passive or active energy recovery. The purpose of the work is to develop a test bench for piston hydraulic cylinders that provides recovery of part of the energy during the test, and at the same time the tests would take place in a mode as close as possible to the real conditions of their operation during their tests, as well as solving the problem of its modeling and calculation of the main functional parameters. In this article, a design scheme of a test bench for reciprocating hydraulic cylinders with active energy recovery and a method for mathematical modeling of the process of its functioning based on the application of the "theory of volumetric rigidity of hydraulic systems" is proposed, which makes it possible to describe with a high degree of accuracy and reliability the processes occurring in the test system during its operation. A scheme of a test bench for piston hydraulic cylinders with energy recovery is proposed. A mathematical model of the stand has been developed and an example of a preliminary calculation of its functioning is given. The proposed modeling method simplifies the modeling process and allows the use of numerical integration methods in calculations. The resulting mathematical model makes it possible to obtain rational parameters of the stand already at the design stage, without resorting to the need for expensive and labor-intensive field studies.

New manufacturing process of cylindrical body products with thickened edge part

The manufacturing process of body products by combining the operations of reverse extrusion and simultaneous formation of thickening at the edges of the workpiece is considered. The simulation of the operation is performed, during which the effect of deformation modes on forces and stress-strain state is determined. According to the results of the study, rational parameters of the process are identified.

Assessment of actual temperature regime in chambers for installation of fans

The article considers an assessment of the safe temperature regime in mine chambers used for the isolated suction of methane from the mined-out space after coal mining. The isolated removal of methane from the produced space outside the mining area through a pipeline with the help of gas-suction fans is used in the Donbas mines. Gas suction units are placed in specially prepared chambers that are ventilated with fresh air. In accordance with the regulatory requirements, ventilation units should be evaluated for air temperature at permanent workplaces in underground workings of coal mines, depending on humidity, air movement speed, and individual categories of work. An analytical comparison of actual temperature regime in the chambers for ventilation gas suction units with permissible norms according to sanitary and hygienic standards was performed. The rational parameters of temperature regime in the chambers for ventilation gas suction units were determined, which can be considered “conditionally” acceptable for the mining and geological conditions in mines of the “Pokrovs’ke” Mine Administration. The substantiation is given to physical parameters of air inflowing into the chambers for ventilation gas suction units needed for their ventilation and in order to maintain sanitary and hygienic standards by temperature. The dependence of the flow rate of air inflowing into the chambers for ventilation gas suction units on its maximum permissible value according to sanitary and hygienic standards is established. It is established that in order to ensure a standard temperature regime in the chambers for ventilation gas suction units in the mining and geological conditions of mines of the “Pokrovs’ke” Mine Administration; it is recommended not to use cooling plants due to their economical impracticability. This will reduce economic costs of ensuring the standard temperature regime. It is necessary to reduce the cost savings on ensuring the standard temperature regime in these chambers and to ensure safe operation associated with the isolated removal of methane from the mined-out space after coal mining.

Визначення раціональних параметрів гасителя низькочастотних коливань великогабаритних інженерних споруд

The article is aimed at determining the rational parameters of a low-frequency vibration damper with rolling elements, which have a simple design and high reliability. The parameters of the damper should be such that its frequency is close to the frequency of the main tone of the structure's vibrations. For this, the natural frequency of the vibration damper is determined under the assumption of small amplitude of the oscillations, which allows the equations of motion to be linearized. At large amplitudes, the nonlinear differential equation of motion is solved by numerical methods that allow finding only private solutions for specific conditions. There is a need to generalize private decisions. For this purpose, one of the simplest dampers was considered, which consisted of a uniform cylinder and a recess (the axes of the cylinder and recess are parallel). It is assumed that there is no energy dissipation and slippage. The cylinder makes free oscillations, which are described by a nonlinear differential equation of the second order. As a result of calculations, the natural frequency and period of natural oscillations of the linearized system were determined. Then, from the condition of conservation of energy, the natural frequency is determined, taking into account the nonlinearity of the system. As a result of numerical integration using the Newton-Cotes method, the dependence of the relative natural frequency and the error caused by the linearization of the differential equation of the cylinder's motion on the amplitude was obtained. Dependence analysis demonstrates a characteristic property of nonlinear systems ‒ non-isochronism. With linearization, an increase in the amplitude of oscillations leads to a quadratic increase in the relative error. As a result of the approximation of the numerical results in the range of values of the angle, which was calculated from the vertical passing through the center of curvature of the depression, from 10 to 900, the dependences of the determination of the relative natural frequency and the error were obtained. In order to determine the accuracy of the obtained dependencies, a comparison was made with approximations obtained by other methods. The comparison shows that the maximum relative error of 0.216039 of the obtained dependence is less than that obtained by other methods – 0.272803, while the calculation is simpler. As a result of calculations and analysis, the following was established. The influence of the amplitude of free oscillations on the frequency is characterized by the relative natural frequency, which shows how many times the natural oscillation frequency of the linearized system is greater than the oscillation frequency of the nonlinear system. The relative frequency depends only on the amplitude of the oscillations. In the case of nonlinear oscillations of a mathematical pendulum and a cylinder, their relative natural frequencies are described by the same function. This allowed the cylinder to use the approximation methods developed for the pendulum. The relative natural frequency of oscillations of the cylinder is determined as a result of numerical integration approximation, as well as by the method of harmonic balance. The maximum relative error of the first method (0.22%) is smaller than that of the second (0.27%), while the calculation is simpler. The error, which is due to the linearization of the differential equation of motion of the cylinder, increases quadratically with an increase in the amplitude of oscillations.

Експериментальні дослідження ширини утвореного валка зрізаної гички коренеплодів цикорію

The search for effective technical solutions and scientific directions for substantiating the rational parameters of the working bodies of hedge cutting devices, which ensure an increase in the production of the strategically important for the leading sectors of the economy of Ukraine (energy - biofuel, food - coffee, pharmaceutical - inulin) culture, or root crops of chicory is a relevant and significant direction research, both for science and practice. The article provides the results of testing the adequacy of the developed analytical model, which functionally describes the process of unloading the cut stubble onto the surface of the harvested field by the transport element (screw conveyor) of the stubble cutting module of the root harvester depending on the parameters of the screw conveyor. Based on the processing of the experimental array of data, the regression equation of the change in the width of the formed swath of cut swath was obtained depending on the input parameters: the speed of the swath harvesting module, the swath yield and the rotation frequency of the screw conveyor. It was found that within the range of variation of the input factors, the speed of movement of the module from 1.6 to 2.4 m/s, the yield of chicory root crops from 120 to 180 t/ha and the rotation frequency of the screw conveyor from 40 to 100 rpm, the width of the formed roll of chopped the width of the swath is in the range from 0.5 to 1.4 m. The difference between the experimental and theoretical values of the width of the formed swath is within 5...10%. The obtained results of scientific research are a further step in the improvement of the methodology for optimizing the rational parameters of the working bodies of root-harvesting machines.

Study of injury of loose material of agro-industrial production by working bodies of flexible screw conveyors

Purpose. Determination of the rational parameters of the process of transportation by the working bodies of flexible screw conveyors with the least trauma to the loose material of agro-industrial production. Methods. The methods of probability theory, mathematical statistics and regression analysis were used for research. Experimental studies of injury of loose material of agro-industrial production depending on the mass of the flexible working body, its rotation frequency and the height of lifting the material. Results. In order to determine the injury of loose material, an experimental setup was developed to study the process of material transportation by flexible wire conveyors. When conducting a multifactorial experiment to determine the injury of loose material of agro-industrial production by the working body of a flexible screw conveyor, the variable factors were: the mass of 1 m of the working body m, the frequency of rotation of the flexible working body n, and the height of lifting the material h. Based on the results of experimental studies, appropriate regression equations and response surfaces were constructed to establish the influence of controlled factors on the injury of loose material of agro-industrial production. The obtained regression equation can be used to determine the injury of grain Y during transportation by a flexible screw conveyor with a sectional working body. Conclutions 1. The method of conducting experimental studies of injury of loose material of agro-industrial production by the working bodies of a flexible screw conveyor has been developed. 2. It was established that the mass of the working body has the maximum influence on the injury of loose material. The next in intensity of influence is the frequency of rotation of the working body. The height of the unloading main has the least significant influence. 3. However experimental studies were conducted for the maximum lifting height of the unloading line h = 1.8 m, which is sufficient for loading machine planters. With a further increase in the value of h, there is a significant increase in the coefficient of filling with the material of the flexible casing, which will obviously lead to more significant damage to the material. Keywords: transportation, loose material of agro-industrial production, flexible screw working body.