scholarly journals ПІДВИЩЕННЯ НАДІЙНОСТІ РОБОЧИХ ОРГАНІВ ҐРУНТООБРОБНИХ МАШИН

Author(s):  
А. А. Дудніков ◽  
О. І. Біловод ◽  
А. Г. Пасюта

У статті розглядаються питання підвищення до-вговічності і надійності робочих органів ґрунтооб-робних машин у процесі їх відновлення (виготовлення)з використанням вібраційних коливань, що сприяютьінтенсифікації методів обробки, підвищенню рівнямеханізації та автоматизації багатьох трудоміст-ких технологій. Показано залежність інтенсивностівібраційного зміцнення від наступних факторів: ре-жиму обробки та фізико-механічних властивостейматеріалу оброблюваних деталей. Встановлено, щоосновними параметрами технологічного процесу віб-раційного зміцнення є збурювальна сила віброзбуджу-вача, амплітуда і частота коливань обробногоінструменту, швидкість і час обробки. The article discusses issues of increasing longevity and reliability of working bodies of tillers in the process of recovery (manufacturing) using vibrations that promote intensification processing methods, increase the level of mechanization and automation of many labor-intensive technologies. The dependence of the intensity of the vibration to strengthen the following factors: the mode of processing, physical and mechanical properties of the material machined parts. Found that the main process parameters of the vibration of hardening is the disturbing force exciter, the amplitude and frequency of oscillation of the machining tool, the speed and processing time.

2017 ◽  
Vol 14 (3-4) ◽  
Author(s):  
Biljana Angjusheva ◽  
Emilija Fidancevska ◽  
Vilma Ducman

Bottom ash has been presented as a major problem of disposal throughout the world, since it is produced from the process of coal combustion in thermal power plants. However, its physical and chemical properties make the bottom ash an adequate potential construction material in variety of applications.The aim of the study was to investigate the possibility of utilization of bottom ash for production of ceramics compacts and to analyse the influence of the main process parameters and their interaction on the physical and mechanical properties of the final product. Consolidation of the powders was conducted on two bottom ash samples with particle size (S) -0.250+0.125 mm and -0.500+0.250 mm, pressing pressure (P) of 100 and 150 MPa and sintering temperature (T) of 1100 and 1150 oC. The density (r) and bending strength (s) of the dense bottom ash compacts were the response function. The optimization was performed through implementation of main effect plots, Pareto charts and 3D surface method using “Statgraphics Centurion” software package. The obtained model equations of the density and bending strength dependence from the main process parameters are solid basic data for modeling the process of ceramic production.


2018 ◽  
Vol 41 (1) ◽  
pp. 27-33
Author(s):  
N.O. Sharkova ◽  
E.К. Zhukotskyi ◽  
Т.Y. Тurchyna ◽  
H.V. Dekusha ◽  
A.A. Makarenko

The use of discrete-pulse energy input (DPEI) mechanisms in various industries has become a reliable tool for the intensification of heat and mass transfer processes in various technological lines and reduction of specific energy consumption. The study of structural transformations in heterogeneous systems under influence of mechanisms of DPEI opens up new possibilities for their use as evidenced by this article. Under certain conditions it is possible to prepare a mushroom suspension with specified characteristics for drying and enhance medicinal properties of the obtained powder product while retaining all valuable components of feedstock. The article presents the results of research of DPEI-processing effect of the shiitake mushroom fruit body on the on physical and mechanical properties and structural characteristics of the mushroom suspension. The influence of hydro module, temperature of the suspension and the layout of the working bodies of the rotor-pulse apparatus (RPA) on its dynamic viscosity was studied and the possibility of reducing viscosity by 2-3 times is shown.  An analysis of mushroom suspension microstructure has showed that with a certain layout of the working bodies of the RPA it is possible to control the degree of dispersion of particles and change the spatial structure of the aggregates in the volume of the dispersion medium. It is determined that self-organization of spatial aggregates from individual hyphae in such suspensions occurs over time. Moreover, the smaller the size of hyphae (≤ 25 microns after the RPA of the first version of the arrangement: rotor-stator-rotor) are, the larger the size of the spatial aggregates are formed. After the RPA with the second layout option, the fragments of hyphae had sizes ≥ 50 μm, but the dimensions of the spatial aggregates were three times smaller. It is found that after three times passing of the mushroom suspension through the RPA and its subsequent treatment in the cavitation device, the dynamic viscosity of the suspension is reduced by 20%. Confirmation of the the effectiveness of the DPEI-mechanisms in obtaining mushroom suspension is that due to the hydromechanical destruction of the polysaccharide structures of the chitin-glucan complex of the shiitake mushroom the content of the bioavailable complex of water-soluble oncostatic and immunoregulatory polysaccharides in the powder obtained by drying the mushroom suspension in an experimental spray dryer increased 6 times. References 13, figures 6.


2018 ◽  
Vol 2 (3) ◽  
Author(s):  
Md. Sahadat Hossain 3 ◽  
Md. Nazrul Islam 1* ◽  
M A Gafur 2

The composites of biodegradable high density polypropylene (HDPE) reinforced with short coir fiber were prepared by melt mixing followed by hot press molding. The effect of fiber addition on some physical and mechanical properties was evaluated. Different process parameters (e.g. mixing time, heating temperature and time, cooling time etc.) were established for good sample preparation The effects of fiber addition on some physical and mechanical properties were evaluated. The mechanical properties were studied via Universal Testing Machine (UTM). The density was increased with the increase of fiber addition. The tensile strength (TS) of fabricated product increased with the increase of fiber addition up to 10% (by wt.) and then decreased continuously. The elongation of fabricated composites was decreased with the increase of fiber addition continuously. The changes in the mechanical properties were broadly related to the accompanying interfacial bonding of HDPE coir composites (HDPECC). To observe the hydrophilicity of the prepared composites was evaluated by the water uptake properties. The interfacial bonding of the fiber and matrix of the coir fiber reinforced composites was studied via scanning electron microscope. It revealed that the introduction of short coir fiber led to a slightly improved mechanical stability of PP- Coir composites. 


2012 ◽  
Vol 62 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Borut Kovačič ◽  
Franc Vrečer ◽  
Odon Planinšek

Spherical crystallization of drugs Spherical crystallization of drugs is the process of obtaining larger particles by agglomeration during crystallization. The most common techniques used to obtain such particles are spherical agglomeration and quasi-emulsion solvent diffusion. Ammonia diffusion systems and crystallo-co-agglomeration are extensions of these techniques. By controlling process parameters during crystallization, such as temperature, stirring rate, type and amount of solvents, or excipient selection, it is possible to control the formation of agglomerates and obtain spherical particles of the desired size, porosity, or hardness. Researchers have reported that the particles produced have improved micromeritic, physical, and mechanical properties, which make them suitable for direct compression. In some cases, when additional excipients are incorporated during spherical crystallization, biopharmaceutical parameters including the bioavailability of drugs can also be tailored.


2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
N. S. Ilicheva ◽  
N. K. Kitaeva ◽  
V. R. Duflot ◽  
V. I. Kabanova

A technique is proposed for obtaining electroconductive, mechanically strong, and elastic composite material based on polypyrrole and hydrophilized polyethylene. The relationship is established between the process parameters and properties of the composite material such as electroconductivity and mechanical strength. Several methods are considered in the view of increasing electroconductivity of the material. Physical and mechanical properties of the composite material are investigated.


2015 ◽  
Vol 21 (5) ◽  
pp. 604-617 ◽  
Author(s):  
Antonio Lanzotti ◽  
Marzio Grasso ◽  
Gabriele Staiano ◽  
Massimo Martorelli

Purpose – This study aims to quantify the ultimate tensile strength and the nominal strain at break (ɛf) of printed parts made from polylactic acid (PLA) with a Replicating Rapid prototyper (Rep-Rap) 3D printer, by varying three important process parameters: layer thickness, infill orientation and the number of shell perimeters. Little information is currently available about mechanical properties of parts printed using open-source, low-cost 3D printers. Design/methodology/approach – A computer-aided design model of a tensile test specimen was created, conforming to the ASTM:D638. Experiments were designed, based on a central composite design. A set of 60 specimens, obtained from combinations of selected parameters, was printed on a Rep-Rap Prusa I3 in PLA. Testing was performed using a JJ Instruments – T5002-type tensile testing machine and the load was measured using a load cell of 1,100 N. Findings – This study investigated the main impact of each process parameter on mechanical properties and the effects of interactions. The use of a response surface methodology allowed the proposition of an empirical model which connects process parameters and mechanical properties. Even though results showed a high variability, additional ideas on how to understand the impact of process parameters are suggested in this paper. Originality/value – On the basis of experimental results, it is possible to obtain practical suggestions to set common process parameters in relation to mechanical properties. Experiments discussed in the present paper provide a variety of data and insight regarding the relationship among the main process parameters and the stiffness and strength of fused deposition modeling-printed parts made from PLA. In particular, this paper underlines the shortage in existing literature concerning the impact of process parameters on the elastic modulus and the strain to failure for the PLA. The experimental data produced show a good degree of compliance with analytical formulations and other data found in literature.


2020 ◽  
Vol 22 (6) ◽  
pp. 2020-2028
Author(s):  
Francisco J. Aranda-García ◽  
Maria M. González-Pérez ◽  
Jorge R. Robledo-Ortíz ◽  
César Sedano-de la Rosa ◽  
Karlos Espinoza ◽  
...  

2014 ◽  
Vol 20 (2) ◽  
pp. 233-240 ◽  
Author(s):  
Violeta Leskevicienė ◽  
Dalia Nizevicienė

Phosphoanhydrite was obtained by processing dihydrate phosphogypsum generated during phosphoric acid production at Joint Stock Company (JSC) Lifosa (Lithuania). The influence on the properties of phosphoanhydrite of the treament process? parameters was determined, including the conditions of phosphogypsum neutralisation in the lime suspension; temperature and duration of calcination of neutralized phosphogypsum to phosphoanhydrite; fineness of ground anhydrite; selection of additives activating the hydration of anhydrite and their amounts. Upon adding activators of anhydrite hydration, K2SO4 or Na2SO4, the data of XRD and IR spectral analysis show that the specimens after 1 day of phosphoanhydrite hydration with additives contain complex salts - syngenite upon using K2SO4 additive and glauberite in the case of Na2SO4 additive. These additives act as crystallization centers and accelerate hydration. It has been determined that the specimens of phosphoanhydrite calcined at a temperature of 900 ? C with 2 % K2SO4 additive have the best physical and mechanical properties. Already after 1 day of hardening the specimens acquired a compressive strength of 21.18 MPa, and after 28 days of hardening they had a compressive strength of 58.5 MPa (dry specimens).


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