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Vol 16, No 1 (2017)
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https://doi.org/10.21122/2227-1031-2017-16-1

MECHANICAL ENGINEERING

5-15 2156
Abstract

Models and methods for presentation of database and knowledge base have been developed on the basis of composition and structure of data flow in technological process of welding. The information in data and knowledge base is presented in the form of multilevel hierarchical structure and it is organized according to its functionality in the form of separate files. Each file contains a great number of tables. While using mathematical simulation and information technologies an expert system has been developed with the purpose to take decisions in designing and process engineering for production of welded ructures. The system makes it possible to carry out technically substantiated selection of welded and welding materials, sttypes of welded connections, welding methods, parameters and modes of welding. The developed system allows to improve quality of the accepted design decisions due to reduction of manual labour costs for work with normative-reference documentation, analysis and evaluation of dozens of possible alternatives. The system also permits to reduce labour inputs for testing structures on technological effectiveness, to ensure reduction of materials consumption for welded structures, to guarantee faultless formation of welded connections at this stage.

16-20 1811
Abstract

Based on the analysis of known methods of separation of bar mix to length determined that the most effective method of forming an annular groove therein plastic tapered section, with a gradual deformation of the metal disc blades recess which is destroyed in the mix zone. In order to reduce the depth of the groove after its shaping proposed to produce in the same local area flexural bar. Based on experimental data obtained an empirical formula relating the dependence of bending rod axis angle on the depth of the annular groove. It is found that the greatest effect on the angle of local bending rod axis in the annular groove zone occurs when changing its depth from 0.5 to 3.0 mm. And this dependence is exponential in nature. Reducing the local axis of the workpiece bending angle for the specified range of the groove depth will be between 8.83º to 2.23º. A further increase in the depth of the annular groove is not practical, because the angle of bending the rod axis with reduced insignificantly. The dependence is valid for the separation process rods tapered disc blades with a local curvature of its axis is almost independent of the original diameter shared assortment. Therefore, the process can be carried out efficiently when the groove depth is not greater than 3.0 mm.

21-27 1043
Abstract

Develop a set equipment for plasma forming ceramic coatings. The article presents characteristics and parameters of the developed complex equipment for formation of plasma ceramic coatings as well as results of its testing. Methods of research is based on studies of structural elements composite plasma coatings system ZrO2 – Y2O3  obtained  using  developed complex equipment. One of the most effective ways to protect the components from high temperature corrosion and oxidation is formation on the surface of plasma thermal barrier coatings. For thermal barrier coating has very strict requirements: сharacterized by a smooth change of physico-mechanical properties (porosity, microhardness, elastic modulus) in the cross section of the metal substrate to the outer ceramic layer; to withstand multiple cycles of thermal cycling from room temperature to the operating temperature; to maintain gastightness under operating conditions and thus ensure a sufficiently high level of adhesive strength. For realization of new technological schemes applying thermal barrier coatings with high operational characteristics was developed, patented and manufactured a range of new equipment. The experiments show that authors developed PBG-1 plasmatron and powder feeder PPBG-04 have at least 2–3 times the service life during the deposition of ceramic materials compared to the standard equipment of the company "Plasma-Technik", by changing the structure of the cathode-anode plasma torch assembly and construction of the delivery unit of the feeder to facilitate the uniform supply of the powder into the plasma jet and the best of his penetration. The result is better plasma coatings with improved operational characteristics: adhesion strength is increased to 1.3–2 times, material utilization in 1.5–1.6 times microhardness 1.2–1.4 times the porosity is reduced by 2–2.5 times.

28-37 1691
Abstract

The article presents a schematic diagram of the Euro-3 diesel engine electronic control and describes hard- and software platform of the high pressure fuel pump pneumatic actuator control that allows to realize the concept of electronic fuel supply control of diesel engine KamAZ-740. The strategic dependence beetwen the angular position of fuel pump governor lever and the angular position of electronic accelerator pedal were put on the basis of electronic control concept. Implementation of this dependence was carried out by applying a modulated PWM signal with determined duty cycle by the controller to the coil proportional solenoid valve, which is responsible for the amount of air pressure in the working chamber of the power air cylinder, connected by articulated-type to the governor lever of the high pressure fuel pump. In this case, the feedback control by position of governor lever of the high pressure fuel pump was introduced in the control circuit, but engine crankshaft speed control was carried out using a software continuous PID governor. Developed strategy gives possibility to track the deflection  of control parameter from a predetermined value by real-time and almost instantly, to make a control action on actuators to eliminate this deflection, while providing a minimum time of transition. Governor’s setting (proportional, integral and differential component) performed empirically using the classical Ziegler – Nichols method, based on the analysis of the safety factor of automatic control system. The results of calculating the coefficients of proportional integral-differential regulator and oscillograms HIL experiment on testing the proposed diesel engine throttle control strategies using visualization CoDeSys V2.3 are given in activity.

38-48 2966
Abstract
The results of the analysis of Minsk city transport system performance. It is shown that the growth of car ownership has caused a number of problems, among which the low-speed communication, bad driving modes, the presence of elevated levels of congestion and accidents. The corresponding figures for accidents in Minsk and some cities in the world that allow to characterize the transport system of the city of Minsk, as satisfactory. To improve the system and improve the quality of traffic necessary to create intelligent transport system of the city of Minsk. Intelligent Transportation System, being a global trend, enables dramatically improve road quality. Automated traffic control system and other subsystems as part of the Intelligent Transportation Systems are tools for achieving the goals for improving the safety and comfort of road users. It is proposed as a base for its creation to choose an automated traffic control system, which has a corresponding functional, structural, organizational and institutional provisions for its development. The technological requirements for the functioning of an integrated system, which relate to the level of efficiency, including accidents on sections of the road network included in the created system. Modernization of the automated traffic control system and its transformation into an intelligent transport system will reduce emergency, economic and environmental, and social costs in the road traffic is not less than 15 % from their current level, despite the steady growth of car ownership in the city. It is planned to create a complete intelligent transportation system.
49-56 3086
Abstract

A method for measuring polymer chemical resistance by dipping specimens in chemical reagents is a standard investigation procedure used in chemical industry (Standards ASTM D543, ISO 155). Such method has been used only for comparative evaluation of chemical resistance for various materials in a number of typical reagents. The results obtained with the help of the method do not provide the possibility directly to estimate application of the given material for this or that products which are used in contact with various chemical environments. It is necessary to take into account such limitations of theused testing results as duration of environmental exposure, temperature and reagent concentration in the medium. If it is as sumed that the method is applied under conditions when a product is continuously contacting with liquid then the results of short-term testings can be used only with the purpose to exclude the least adequate materials. Testing equipment has included a precision chemical balance, a micrometer, a container for immersion medium, a thermostat for setting and maintaining the required temperature and devices for measuring physical properties. Dimensions and type of a test specimen are specified by the shape of material which is used for testing. At least three specimens are needed for testing in every reagent. Changes in dimension and weight are measured for every specimen. The specimen is placed in container for 7 days in standard laboratory atmosphere where it should not touch a bottom or walls of the container.

57-67 1112
Abstract

The paper presents results pertaining to investigations of traffic conditions and intensity of traffic and pedestrian flows, calculations on loading level of objects located in the Makayonka Street, Minsk. The objects constitute transport regional development which presupposes reconstruction of regional arterial street with due account of infrastructure improvement,   residential  construction and  construction  of  multi-purpose  complex  with   shopping,  entertainment,   wellness  and business centers. In addition to this it is planned to construct a two-level underground parking, a two-level interchange at intersection of the Filimonova Street and Nezavisimosty Avenue due to an increase of traffic load at adjacent neighboring street and road network. An analysis on the current traffic management and calculation for distribution of the existing and prospective traffic load levels after implementation of appropriate measures to improve quality as a whole and road safety as well has been carried out in the paper. Determination of loading levels for a street and road network has been carried out while taking into account an intensity of traffic flows in order to evaluate various options for road traffic organization. Variants for planning of road junctions, road traffic organization and traffic signalization (including coordinated passing of  transport facilities) have been developed in the paper. All this will contribute to improvement of quality and road safety in the investigated street with due consideration of further development of the region and overbuilding of the existing housing system in the Makayonka Streets and increase of its transport importance in the Minsk street and road network.

68-72 2047
Abstract

Crane wheels and rails are subjected to intensive wear in the process of operation. Therefore, improvement of these components’ performance can be considered a task of high importance. A promising direction in this regard is surface treatment by highly concentrated energy flows such as laser beams or plasma jets. This thesis suggests that the use of gradient plasma surface treatment can improve the performance of crane rails. A research was conducted, according to which hardened zones were deposited on crane rails under different treatment modes. Microhardness was measured both at the surface and in depth using custom-made microsections. The article includes the results of study of plasma surface hardening effects on wear resistance of crane rails. Change of plasma surface treatment parameters (current, plasma torch movement speed, argon gas flow rate) allows for desired steel hardness and structure, while the choice of optimal location for hardened zones makes it possible to significantly improve wear resistance and crack resistance. As a result of plasma surface hardening, the fine-grained martensite structure is obtained with mainly lamellar morphology and higher hardness rate compared toinduction hardening or overlaying. Wear test of carbon steels revealed that plasma surfacing reduces abrasive wear rate compared to the irinitial state by 2 to 3 times. Enough sharp boundary between hardened and non-hardened portions has a positive effect on the performance of parts under dynamic loads, contributing to the inhibition of cracks during the transition from solid to a soft metal. For carbon and low alloy rail steels, the properties achieved by plasma surface hardening can effectively replace induction hardening or overlaying.The mode range for plasma surface treatment that allow sobtaining a surface layer with certain operating properties has been determined.

73-82 2099
Abstract

Dependence of tractor wheel torque on theoretical tractor motion speed has been used for comparison of tractor operation with electromechanical transmission with installation of energy accumulating mechanism and without its installation. In this case a traction asynchronous electric motor is operating under nominal and limit conditions. The paper also considers dependence diagrams of actual input power for the traction asynchronous electric motor and its losses due to theoretical tractor motion speed. Tractor wheel torque is limited during the operation of the traction asynchronous electric motor with energy accumulating mechanisms by the following factors: maximum electric motor torque at the given frequency of supply voltage; maximum value of internal combustion motor output which can be transferred to the traction asynchronous electric motor; grip of the wheels. During the operation of the traction asynchronous electric motor with energy accumulating mechanisms there is a possibility for short power consumption without regard to the second limitation because it is possible to use power not only of internal combustion motor but also the power which is stored in the energy accumulating mechanisms. Comparison of characteristics has been made when a tractor is operating at high gear and when it is operating at all gears (that is two gears). Operation of the 5th class tractors has been analyzed for all possible cases (operation with energy accumulating mechanisms and without the mechanisms while being operated at all gears) and various types of work: tilling, sowing, cultivation, bulldozing work, transport mode. In this case equipment has been used which is aggregated with the 5th class tractor. 

83-88 3053
Abstract
The paper presents results of investigations on the process pertaining to interaction of a driving wheel with ground surface and describes methodology for optimization of backbone parameters. The mentioned process has some specific differences in comparison with the process of wheel rolling along hard surface. Ground surface is represented by mixture of sandy and clay particles with plant residues and it has a number of physical and mechanical properties. The main of these properties is resistance of soil against compression and displacement. Compression process determines a track depth and resistance to motion and displacement process determines wheel gripping property and its tangential traction force. While executing the investigations laws of compression and displacement proposed by Prof.V. V. Katsygin as the most adequate reflection of actual processes have been used in the paper. Motion of the driving wheel along ground surface is accompanied by its slipping. It has been determined that the maximum wheel traction force is formed not with 100% slipping as it was supposed until present but the value has been obtained at 45–60 % slipping according to soil category. The developed integral equations with due account of the aspect make it possible to calculate road hold characteristics of driving wheels of the designed wheel tractor and evaluate its traction, speed and economic characteristics. Methodology has been developed for optimization of backbone parameters of wheeled running gear in the designed tractor such as design mass and adhesion weight, width, diameter and air pressure in a tire. The proposed methodology has been introduced in designing practice of wheeled tractors at OJSC “Minsk Tractor Works”.


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ISSN 2227-1031 (Print)
ISSN 2414-0392 (Online)