No 2 (2021)

Articles

Applied science and manufacturing: NAMI and VTZ

Grudskiy Y.G.

Abstract

Starting from the 1960s, a number of acute problems appeared in the engine building during the transition to diesel engines of a new generation, the engines with direct fuel injection into the chamber in the piston. The short time allotted in the cycle for mixture formation and combustion, especially for high-speed diesel engines, makes it extremely scrupulous to approach this in order to obtain high and stable technical and economic indicators. One of the many problems is the organization of efficient and uniform gas exchange across the samples to reduce the spread of final indicators during mass production. The article deals with this very problem, specifically - in the case of chill casting of individual heads at the Vladimir Tractor Plant (VTZ) using composite rods of inlet and outlet channels. The method of static blowing of inlet channels developed at Central research and development automobile and engine institute NAMI with a quantitative assessment of the resistance and vortex formation in the cylinder was applied. The gas-dynamic parameters (GP) were checked for the heads that received individual numbers in a statistically significant sample of billets on one test bench several times, sequentially according to the stages of the processing. It is shown schematically how these parameters changed during processing and assembly of the heads. It is important that a high “hereditary” correlation is obtained between the GP of the billets and fully machined and assembled cylinder heads. The manufacturing cost of the latter is incommensurably higher than the castings cost. Therefore, according to the results of the work, in order to reduce the cost of products and increase the level and stability of quality, an important decision was made on the early flaw detection of the GP (after casting) with the subsequent remelting of those blanks that are most likely “genetically, hereditarily” will not provide the declared technical and economic indicators in assembled product. Similar approaches can be used in the organization of production and other goods with high added value of technological operations required after procurement to ensure the quality of final products.
Tractors and Agricultural Machinery. 2021;(2):6-15
pages 6-15 views

Determination of the optimal composition of mixed fuel based on environmental indicators of diesel engine

Plotnikov S.A., Gnevashev P.V.

Abstract

Alternative motor fuel is a mixture of various hydrocarbons and their compounds. Motor fuel is based on naphthenic, paraffinic and aromatic hydrocarbons. The performance characteristics of the fuel depend on its composition. When developing methods for monitoring the characteristics of fuels, the main problem is their multicomponent nature, since each component contributes to the operational characteristics. The operational characteristics are: cetane number, sulfur content, water-soluble acids and alkalis, lower heat of combustion and some others. To determine them, the combustion of diesel fuel (DF) and the subsequent analysis of the combustion products are carried out. The disadvantage of the existing method is the fact that it is impossible to quickly control the fuel at the place of operation, at a tank farm, a gas station, a process pipe or a vehicle fuel tank. When designing analyzers and measuring instruments the correlation dependences, which link the value of the operational property of the fuel with its physicochemical characteristics, are used. Taking into account the use of various types of alternative fuels (AT) with a wide range of their operational properties, the problem of a quick and accurate preliminary assessment of these properties arises. Along with diesel fuel, it is proposed to use similar physicochemical methods to assess the flammability of alternative fuels.
Tractors and Agricultural Machinery. 2021;(2):16-20
pages 16-20 views

Digital rotation meter

Gerashchenko V.V., Lobakh V.P., Kovalenko N.A., Bilyk O.V.

Abstract

There was developed a digital universal measuring device for the rotation frequency of various parts: a gear wheel, a splined shaft, a special disc with slots, etc. The use of a 16-digit summing electronic counter makes it possible to form a digital code up to 65536 pulses per second, which makes it possible to install it on almost any vehicle. At the same time, it has simplicity, low cost, reliability and accuracy. The design of the meter includes a signal transducer, a self-oscillating multivibrator, logic elements, and an electronic summing pulse counter. The sensor of the meter is made in the form of an inductance coil with a magnetic core. The first differentiating circuit with a diode is used as a converter of the sensor signals, connected to a logic AND gate, which is connected by its output through a resistor to the counting input of the counter. The input of the second differentiating circuit and the second input of the logical element AND are connected in parallel with the output of the self-oscillating multivibrator, and the input for setting the zero of the counter is connected in parallel with the output of the second differentiating circuit. The self-oscillating multivibrator is symmetrical, and the resistance of its resistors and capacitors are selected in such a way that the formation of rectangular voltage pulses and pauses duration of 1 second at its output is ensured. The presence of a sixteen-bit summing electronic counter, consisting of 16 triggers and having 16 outputs and 16 light-emitting diodes, each of which is connected to one of the outputs of the counter, allows, when the meter is turned on, to receive digital codes at their output in one second, showing the speed. An example of calculating the elements of the differentiating circuit of a multivibrator is given. The experiments have confirmed the efficiency of the developed rotational speed meter.
Tractors and Agricultural Machinery. 2021;(2):21-26
pages 21-26 views

Methods for controlling the elastic damping characteristics of pneumatic seat suspensions

Lyashenko M.V., Shekhovtsov V.V., Potapov P.V., Iskaliyev A.I.

Abstract

The pneumatic seat suspension is one of the most important, and in some situations, one of the key components of the vibration protection system for the human operator of the vehicle. At the present stage of scientific and technical activities of most developers, great emphasis is placed on controlled seat suspension systems, as the most promising systems. This article analyzes the methods of controlling the elastic damping characteristics of the air suspension of a vehicle seat. Ten different and fairly well-known methods of changing the shape and parameters of elastic damping characteristics due to electro-pneumatic valves, throttles, motors, additional cavities, auxiliary mechanisms and other actuators were considered, the advantages, application limits and disadvantages of each method were analyzed. Based on the results of the performed analytical procedure, as well as the recommendations known in the scientific and technical literature on improving the vibration-protective properties of suspension systems, the authors proposed and developed a new method for controlling the elastic-damping characteristic, which is implemented in the proposed technical solution for the air suspension of a vehicle seat. The method differs in the thing that it implements a cyclic controlled exchange of the working fluid between the cavities of the pneumatic elastic element and the additional volume of the receiver on the compression and rebound strokes, forming an almost symmetric elastic damping characteristic, and partial recuperation of vibrational energy by a pneumatic drive, presented in the form of a rotary type pneumatic motor. In addition, the method does not require an unregulated hydraulic shock absorber, while still having the advantage of improved vibration-proof properties of the air suspension of a vehicle seat over a wide range of operating influences.
Tractors and Agricultural Machinery. 2021;(2):27-33
pages 27-33 views

Modeling the parameters of free and driving wheel rolling modes taking into account the asymmetry of the normal reaction diagram

Romanchenko M.I.

Abstract

A method for determining the power and kinematic parameters of a tire and a wheel for free and driving modes of rolling is given. The displacement of the center of normal reactions of the road support surface was taken into account. The amount of displacement is presented as a linear function of the longitudinal force coefficient. The analytical description of the dependence reflects the relationship between the longitudinal force coefficient and the asymmetry coefficient of the diagram of normal reactions of the bearing surface and determines the displacement of the center of normal reactions towards the front edge of the contact area of the tire. The calculated asymmetry of the epure of relative normal reactions can be obtained by choosing the appropriate value of the asymmetry coefficient in the range from 1 to 0. Based on a numerical example, a graphical-analytical display of the force and kinematic parameters of rolling of a wheel with a 15.5-R38 model F-2A tractor tire is presented when using the epure of relative normal reactions described by a parabolic dependence of the fourth degree. The longitudinal force coefficient is determined taking into account the formation of the resulting longitudinal reaction by two components - in the slip section and in the rest section of the tire contact pad elements. It was found that the maximum value of the longitudinal force coefficient for an asymmetric epure of relative normal reactions is observed with a larger value of the wheel slip coefficient compared to a symmetric epure, but remains practically unchanged for both compared diagrams of relative normal reactions. The presented method for determining the power and kinematic parameters, taking into account the asymmetry of the epure of normal reactions of the supporting surface, can find practical application in the selection and substantiation of rational modes of operation of wheel propellers of tractor transport and technological units in various road conditions.
Tractors and Agricultural Machinery. 2021;(2):34-44
pages 34-44 views

The influence of hardening on the operational properties of soil-cutting tools

Markov B.A., Sedykh O.V., Bondarenko V.V.

Abstract

Today, soil cutting tools are mainly made from carbon steels, which are heat treated to provide high hardness and strength. However, at present, the durability of such a hardened soil-cutting tool of both domestic and foreign manufacturers is far from perfect. One of the reasons for the insufficient resistance to abrasive wear of a soil-cutting tool subjected to hardening by heat treatment may be its heating by frictional force in contact with the soil. As a result of such heating, the steel undergoes additional tempering, which leads to a decrease in the surface hardness of the cutting edge of the tool by almost 2 times - 49-50 HRC to 22-34 HRC, depending on the intensity of metal heating. This circumstance was established during metallographic studies of samples cut from the shares of the KB-01 body of the PBS-4 plow. One of the ways to solve this problem is to obtain a wear-resistant layer on the surface of the soil-cutting tool, which is not subject to the negative effects of reheating during operation, for example, from alloyed white cast iron by the method of plasma-powder surfacing. Metallographic studies showed that the deposited layer has a hardness of more than 62 HRC. At the same time, such types of heat treatment as hardening, normalization or annealing do not have a noticeable effect on the hardness of the deposited layer. Metallographic studies of the deposited metal after operation also showed the absence of noticeable changes in its microstructure and hardness. This indicates that reheating from the action of friction forces does not have a significant effect on the properties of a soil-cutting tool strengthened by plasma-powder surfacing, which contributes to an increase in its duration of operation.
Tractors and Agricultural Machinery. 2021;(2):45-51
pages 45-51 views

Comparative analysis of methods for improving the quality of hardened pipe and bar stock for agricultural machinery parts

Dement'yev V.B., Zasypkin A.D.

Abstract

The problem of obtaining a high-quality surface is acute in thermal, chemical-thermal and thermomechanical processing of products of rolling production. But, due to the fact that many metallurgical plants are insufficiently equipped with cleaning tools for these types of processing, the required surface quality of metal products is not ensured. Operations related to the removal of defects in the surface of rolled products employ from 30 to 60% of the workers in rolling shops. The need for cleaning leads to a rupture of the production flow, since the metal must be pre-cooled for inspection and cleaning of defects. As a result, the total cost of cleaning is 2 - 3 times higher than the cost of performing the main technological operations - heating and deformation of the metal. In this regard, the combined methods of hot rolling with simultaneous hardening and elimination of surface defects are of particular interest, which gives significant energy savings and excludes etching operations in solutions of sulfuric and hydrochloric acids. The paper considers new methods for stripping rolled stock before deformation in the high-temperature thermomechanical treatment (HTMT) mode of cylindrical hot-rolled solid and hollow billets with screw compression (SC) deformation, combining, along with a high-performance method of shaping and strengthening of rolled products, environmentally friendly (acid-free) methods of surface cleaning, as well as methods of removing surface layer defects combined with mechanical processing. At the same time, simultaneously with cleaning the surface and increasing the accuracy of rolled products, the structure of the surface layer is formed by the mechanism of phase transformations during thermomechanical processing. The type of fracture changes at low-temperature destruction from brittle to ductile. It should also be noted, that there is the need for further development of such well-proven cleaning methods as blade and waterjet processing, which allow, when cleaning rolled products from any steel grades from scale, to implement the most reliable cleaning system, ensure effective removal of surface and deeper defects, increase yield, reduce energy consumption and fit well into the continuous rolling mill line. According to recent studies, waterjet treatment increases the fatigue life of hollow cylindrical parts by up to 15%.
Tractors and Agricultural Machinery. 2021;(2):52-60
pages 52-60 views

Threshing and separating device

Sobolev M.O., Tarasenko B.F., Mechkalo L.F., Voynash S.A., Sokolova V.A.

Abstract

The article presents a brief analysis of the technology of harvesting grain crops and technical means, from which it follows that one-section threshing-separating decks structurally look as follows. The “sockets” for their installation in the combine are fixed on the side cheeks, which, in turn, are rigidly connected to the transverse strips, installed between them at a uniform interval along the entire length of the deck, and the transverse strips with their inner side are located on a cylindrical surface with a certain drum wrap angle. At the same time, to increase the rigidity of the transverse strips and the entire deck as a whole, below the surface of the bar tier, the transverse strips are interconnected by rectangular ribs curved along a concentric circle of a larger radius than the radius of the working surface of the separating grid. All decks are installed on the combine with respect to the outer diameter of the drum beaters, not along a concentric circle, but with an offset. Therefore, the principal disadvantages of single-drum single-section decks are the high levels of under-threshing, loss of free grain in the coarse heap through straw walkers, and especially crushing. In this connection, there is a need for its improvement, as well as the need to modernize the threshing-separating device with an improvement in the operation of the air-sieve cleaning. On the basis of prospecting studies, a single-section threshing deck protected by the RF patent was proposed. The deck consists of at least three zones. In the first zone of threshing and separation the separating grid is made two-tier, with a variable distance between the tiers by means of a variant installation under the main tier of removable bars of the grid, located on the transverse slats with a step t larger on radii than those of the main tier, passing in the middle of the step bars of the main upper tier with intervals from 0.75 to 1.25t. In the second zone of separation and threshing the separating grid with a length of 5 to 12 intervals between the transverse strips is single-tier, but the step between the grid bars located on the continuation of the tier of the first zone on the transverse strips of the zone is at least 1.5t of the step. In the third zone of final threshing and separation with a length of no more than 6 intervals between the transverse slats, a single-tier grating is a continuation of the upper tier of the first zone with a bar pitch from 0.5 to 1.5t of the first zone pitch. This solution has practical significance and perspective for implementation by installing them on self-propelled grain harvesters.
Tractors and Agricultural Machinery. 2021;(2):61-67
pages 61-67 views

Modernization of the apparatus for grinding root crops

Shukhanov S.N., Dorzhiev A.S.

Abstract

The sustainable functioning of the agro-industrial complex largely determines its scientific and technical support. One of the key directions of the development of agricultural science is the mechanization of animal husbandry processes. When solving a complex of problems, great attention is paid to the preparation of feed for feeding, namely the grinding of root-club crops. This makes it possible to significantly increase the return of each feed unit. As a result of a wide review of literary sources, a thorough analysis of modern designs of root-club grinders, it was possible to solve the technical problem of its modernization by creating a simple as well as reliable design. The peculiarity of the modernization consists in the fact that the electric motor is mounted on the cover of the housing with the help of a flange, which is its component element, besides, the axis of rotation of the shaft structure is aligned with the axis of rotation of the disk structure. Loading hopper is also installed on cover. For this purpose, the cover has a hole for the driving shaft of the electric motor, as well as a window for passage of root clubs from the cavity of the receiving hopper to the space of the housing. Disk is rigidly mounted on free edge of shaft structure. Body is fixed on base by means of uprights vertically and with formation of free space under its bottom and base for installation of unloading neck, as well as reservoir for treated root-club beds. The discharge neck is structurally made in the form of a funnel, moreover, with the formation of a conical component at the top and a cylindrical component at the bottom. In addition, the axis of symmetry of the funnel is aligned with the axis of rotation of the shaft. Its conical component is attached to the outer surface of the bottom structure, and the cylindrical component of the funnel is oriented to the container for the treated material. Concentric holes are made in bottom for passage of processed root-and-root beds from cavity of body into structure of discharge neck. The principle of energy saving is carried out by supplying treated fodder to the discharge neck device and further to the receiving vessel mainly due to gravity of the treated fodder.
Tractors and Agricultural Machinery. 2021;(2):68-72
pages 68-72 views

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