The paper presents a computational method that allows to predict the process of drainage of flax seeds with expanded perlite and biohumus for complex pre-sowing treatment with preliminary irradiation of seeds in the infrared range. From a methodological point of view, in the process of seed granulation, the efficiency depends on the adhesive bond arising in the process of rolling and dispersing. To solve this problem, the calculations of mathematical models of the process of granulation of seeds and the process of dispersion of perlite with biohumus on the surface of seeds were carried out in order to obtain a finished dragee with components of natural origin and improve the sowing qualities of treated seeds and the finished product. As a result of the developed models, analytical solutions of kinetic problems for the process of precipitation of particles of a draining mixture of perlite and biohumus on the surface of flax seeds are obtained. The described mathematical model allows to determine the technological parameters of the granulation process-particle size of the granulating mixture and granulation time, for the calculation of granulating components in the development of technological equipment for granulation. The approximation of the obtained data was made, which showed the prospects and effectiveness of the ongoing developments.
Today, new methods of manufacturing complex parts using three-dimensional printing are being introduced in engineering, including in the mechanical engineering of agricultural machinery. This technique is also used in the design of agricultural machinery at the stage of physical modeling of their structures to determine certain properties of the product as a whole and its individual parts (details) on the corresponding models. Physical modeling is used when it is difficult to perform full-scale tests of the product, as well as for economic reasons. The necessary conditions for physical modeling are the geometric and physical similarity of the model and kind. The presence of such proportionality allows us to recalculate the experimental results obtained for the model in kind by multiplying each of the determined values by a constant multiplier for all values of this dimension – the similarity coefficient. However, to study the physical characteristics of a product, it is necessary to take into account the mechanical properties of the material of its model. From various sources, you can find the main mechanical characteristics of plastic threads or samples made on a 3-D printer. Their values vary greatly depending on the model manufacturing technology. The paper presents the results of a study of the physical and mechanical properties of polylactide (PLA) and polyethylene tereflatate (PET-G), which are used in the manufacture of parts by three-dimensional printing. The specific strength of polymers was respectively: for PLA 65.6…12.2 kPa·m3/kg, for PET-G 36.7…95.4 kPa·m3/kg. Specific plasticity for PLA is equal to 60.,3 %· cm3/kg, for PET-G – 468.2 %· cm3/kg. The specific plasticity for PLA is 608.3 %· cm3/kg, for PET-G – 468.2 %· cm3/kg. Mechanical properties are investigated and the obtained mechanical characteristics must be taken into account when calculating and physically modeling plastic products for three-dimensional printing.
Increasingly, parts of complex shapes are made using three-dimensional printing. This technique is also used in the design of equipment at the stage of physical modeling of their structures to determine certain properties of the product as a whole and its individual parts (details) on the corresponding models. The necessary conditions for physical modeling are the geometric and physical similarity of the model and kind. The presence of such proportionality makes it possible to recalculate the experimental results obtained for the model in kind by multiplying each of the determined values by a constant multiplier for all values of this dimension – the similarity coefficient. However, to study the physical characteristics of a product, it is necessary to take into account the mechanical properties of the material of its model. From various sources, you can find the main mechanical characteristics of plastic threads or samples made on a 3-D printer. Their values vary greatly depending on the manufacturing technology of models and are determined under conditions of static loading only, which is not enough to study the stress-strain state of parts that are affected by suddenly applied, long-term and dynamic loads during machine operation. This paper presents the results of a study of the physical and mechanical properties of polylactide (PLA) and polyethylene tereflatate (PET-G), which are used in the manufacture of parts by three-dimensional printing. The specific stiffness of polymers was for PLA 1.61…2.18 MPa·m3/kg, for PET-G – 1.15…1.41 MPa·m3/kg. The specific impact strength for PLA is 751.6…774.2 J·m/kg, for PET-G – 571.6…583.0 J·m/kg. The specific endurance for PLA was 1.75…2.76 kPa·m3/kg, for PET-G – 3.0…3.10 kPa·m3/kg.
Now in agricultural production there are significant changes in the fleet of equipment due to the renewal of the material and technical base with improved parameters for quality, reliability, durability and operability in difficult operating conditions. However, the manufacturing industry still has a large number of outdated equipment that requires modernization through optimal design of machine components and parts. So, in the process of feed preparation, closed-type grain crushers are widely used, working on the principle of suction of the source material and injection of the finished product. This type of crushers undergoes significant abrasive wear of working bodies (drums, hammers, sieves, etc.) due to their suboptimal geometric shape of transition surfaces, where local stresses accumulate, as well as in areas of contact of parts with particles of gas-dispersed material. The blades of the drum wheel are subjected to particularly severe wear, for the restoration of which significant material costs are required during major repairs. The paper presents theoretical studies of contact stresses during wear of working surfaces, a criterion and condition for the optimal position of the blade are proposed. The optimal position of the blade has been determined - it must be positioned at an angle of 10 ° to the axis of the drum wheel. The results of field tests of the upgraded crusher allow us to conclude that the reliability indicators (durability of the blade drum and reliability of the crusher) increase by more than 3 times.
Currently, in the manufacture of agricultural products in the process of feed preparation, closed-type grain crushers are widely used, working on the principle of suction of the starting material and injection of the finished product. This type of crushers undergoes significant abrasive wear of working bodies (drums, hammers, sieves, etc.) due to their suboptimal geometric shape of the transition surface, where local stresses accumulate, as well as in the areas of contact of parts with particles of gas-dispersed material. It is possible to investigate the causes of the rapid destruction of the working bodies of the crusher by theoretical methods and modeling of physical processes, which will increase the speed, economic efficiency, reliability in the design of components and mechanisms, as well as optimize the design of the upgraded paddle wheel. The paper presents a theoretical model of the stress state on the working surface of the blade, the adequacy of which is confirmed by experimental data with a correlation coefficient of more than 0.95. Studies have allowed optimizing the position of the blade, at which it must be positioned at an angle of 10 ° to the axis of the wheel of the crusher drum, while the contact stresses on the wear surface are distributed almost evenly. This design change will lead to uniform wear of the blade and, as a result, to an increase in durability and reliability of the crusher.
Physical and mechanical properties of the polymeric sand used as floor covering in cattle stalls were investigated. Samples of the polymeric sand were tested under static and dynamic stress, an impact test was done, mechanical characteristics were measured, and the material structural efficiency was evaluated. The polymeric sand tile appeared strong, reliable and durable material. The study material exhibited viscoelasticity. The polymeric sand samples demonstrated impact viscosity in the range 242,3– 548,3 kJ/m2 . The figure was 3,5–13,7 times higher than that of gray cast iron and was comparable with some classes of carbon structural steel. Mechanical properties of the polymeric sand were analysed. The characteristics revealed in the analysis can be used in dimensioning and designing products made from polymeric sand under various strength indices.
A method for optimal designing of parts and units is presented. Its application will allow to increase the structural reliability of agricultural machinery.
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