Machines. Technologies. Materials.
Vol. 11 (2017), Issue 7

Table of Contents

  • MACHINES

    • FLOTATION DEVICE WITH A HIGH FREQUENCY ROTARY PULSATION AERATOR (HFRPA) FOR ENRICHMENT OF FINE-GRADE GOLD-CONTAINING ORES

      pg(s) 327-331

      On the manufactured enlarged version of the flotation device with a high-pressure rotary pulsating aerator (HFRPA), investigations and tests were conducted on refractory finely minified gold-bearing ore samples. The experiment and practice of flotation with the developed by the authors HFRPA showed that the pressure fluctuations created by the aerator ensure the efficiency of the functional use of the two periods. Which is the dissolution of additional gases in the high-pressure compression period, which ensures the aeration process with the required amount of dissolved gases and pseudo cavitation emission of gases in the medium rarefaction period, and this provides aeration with gas separation from the aqueous phase directly on hydrophobic mineral micro particles, i.e. micro dispersions selective flotation.

    • ENERGY ANALISYS AND WASTE HEAT RECOVERY POTENTIAL OF AN AUTOMOTIVE DIRECT INJECTION DIESEL ENGINE

      pg(s) 332-335

      The article presents a numerical analysis of energy balance of an automotive diesel engine and exergy analysis of exhaust gas and cooling systems. A model of the engine was built in advanced simulation code AVL Boost. In order to validate the model a comparison between estimated and real engine effective power was conducted at full load. Energy balance revealed a maximum engine efficiency of 42.1% at full load and 2000rpm. The highest quantity of lost energy contains the exhaust gas. The maximum estimated exhaust gas enthalpy is 108kW at 4000rpm. At the same operating point the cooling enthalpy more than twice lower – 40.2kW. At the engine speed lower than 2000rpm the lost energy in exhaust gas and cooling system has the same quantity. The exergy analysis revealed that waste heat recovery potential in exhaust gas is much higher than cooling system. The results obtained in this study will be further used in a Rankine-Hirn waste heat recovery system development due to increase overall engine efficiency.

    • STUDY THE INFLUENCE OF ROTATION SPEED ON DEFORMATION PROCESS FOR FLEXIBLE COUPLER WITH RUBBER ELASTIC ELEMENT

      pg(s) 336-339

      When operating with flexible couplers with a rubber elastic element according by standard BDS 16420:86, a plastic deformation of the tire is observed after a certain period of time. To investigate the deformation process of the elastic element and to determine the main parameters that affect it, it is necessary to develop a computer model and observe the deformation process when changing the factors of greatest impact. For CAE program in witch is analysing the model is choosing Solid Work Simulation. The results obtained in the study give a clear picture of how the deformations obtained are influenced by the parameters characterizing the operation mode. These results will be used in the design of a elastic element with which the coupler design will operate flawlessly for a longer period of time

    • SAFETY RELATED ASPECTS OF HUMAN MACHINE INTERFACE REGARDING INVEHICLE ITS AND ELECTRIC VEHICLES

      pg(s) 340-345

      The launch of electric vehicles and ITS initiated new challenges for design related ergonomics in the vehicles, especially in the field of Human Machine Interface (HMI). This research is motivated by the necessity for evaluation of current ergonomic and design solutions of contemporary vehicles. The presented study included a review of available literature and regulations, state of the art, as well as operational analysis based on detailed comparison between two vehicles. The assessment has been done between two existing vehicles of the same model, the first one powered by the internal combustion engine, and the other one powered by an electric engine. The information displays, vehicle controls and secondary vehicle controls of both vehicles were carefully analyzed and compared. The results of the study are presented as a source of preliminary understanding of the newly developed technology for designers, experts dealing with safety issues and other professionals.

  • TECHNOLOGIES

    • ELECTRIC DISCHARGE METHOD OF OBTAINMENT OF TITANIUM CARBIDE HARD METALS

      pg(s) 346-349

      A complex approach to obtainment of titanium carbide hard metals, which consists of utilization of high density energy flows of high voltage electric discharges (HVED) for dispersion and activation of particles of powders mixture of 80 % Ti + 20 % Fe composition and synthesis of carbide phase and subsequent consolidation of obtained powders mixture by high density electric current with spark plasma sintering (SPS) method. Connection between specific cyclic energy of treatment of “kerosene – Ti + Fe powders mixture” disperse system and changes of dispersity, shape and phase composition of powders and physical and mechanical properties (hydrostatic density, hardness, thermal conductivity, wear resistance, dynamic strength) of materials consolidated from them is found. Tungstenless titanium carbide hard metals, which have high specific values of strength and wear resistance, hardness of which is higher than 82 HRA, and thermal conductivity of such materials is insignificantly lower than thermal conductivity of VK6 alloy, were obtained

    • DEVELOPING THE TECHNOLOGY OF WASTE SULFURIC ACID LEACHING OF CHRYSOTILE ASBESTOS PRODUCTION

      pg(s) 350-352

      The conducted experiments with the waste asbestos production of the fraction -0,5÷+0,074 mm at 40-100% changes of expense of sulfuric acid for magnesium oxide sulfation allowed to control the residual magnesium content in the filter cake and sulfuric acid in the solution, the degree of magnesium and iron extraction in productive solutions, the speed of lightening productive solutions. The investigations proved that there is ability to make leaching and two-stage rinsing of the filter cake in one unit

    • THE EXPERIMENTAL DETERMINATION OF L/D RATIO USING WATER IN MINI CHANNELS TO ANALYSIS OF FLUID TEMPERATURE PERFORMANCE WITH NANO PARTICULATES

      pg(s) 353-355

      Nano fluids is advantageous with high thermodynamic properties compared to pure fluids. In the last half century, rapid developments in production technology, which allows high-precision production of the micro heat exchangers and the use of the micro heat exchangers in different areas. These developments point researchers to enhance new methods in improving the heat transfer. One of these methods is; to improve fluid’s heat transfer by adding different particulates to the fluid. The nano fluids are the new type of heat transfer fluids that are made by adding nano particulates which has high thermal conductivity to a conventional fluid. Since the solid metal has a higher thermal conductivity than the basis fluid, the addition of the metallic particulates to the fluid increases the heat transfer of the mixture. In this study, for analyzing the temperature performance of fluids with Nano particulates; an experimental study was performed using water to determine the optimum mini channel length and mini channel diameter. Performance parameters are; channel length, tube mini channel diameter, the flow and the inlet temperature. According to the experimental results, the maximum temperature performance of the mini channel was found to be at L/D=250/3 (at Selcuk University condition). Therefore, with these results, the optimum mini channel length and mini channel diameter are determined for the high efficiency that is to be achieved by using nano fluids

    • TOOL LIFE MODELING BASED ON CUTTING PARAMETERS AND WORK MATERIAL HARDNESS IN TURNING PROCESS

      pg(s) 356-359

      In this paper we have presented methodology for development of life prediction model for first order tool during turning of hardened 42CrMo4 steel at different levels of hardness. It is important to be able to predict and describe the tool life in regards to manufacturing costs during industrial production. Tool life is defined as the of cutting time that tool can be used. Cutting tools can be used when they do not reach tool life criteria and can produce parts with desired surface finish and dimensional accuracy. Flank wear of cutting tools is often selected as the tool life criterion because it determines the diametric accuracy of machining, its stability and reliability. Tool wear is defined as a gradual loss of tool material at contact zones of workpiece and tool material, resulting the cutting tool to reach its life limit. This paper investigates the tool wear of TiN coated tungsten carbide inserts under dry cutting, using the central composite design of experiments method (DoE) with three factors at three levels. By using the multiple linear regression analysis between cutting speed, feed rate and depth of cut, it determines the effects of cutting conditions on extended Taylor’s tool life equation.

    • ELECTROCHEMICAL TREATMENT OF WASTE IN THE FORM OF COPPER COATING ON NON-CONDUCTIVE SUBSTRATE TO OBTAIN MARKETABLE PRODUCTS

      pg(s) 360-363

      Technology for copper coatings removing from spent parts made of dielectric by anodic dissolution without formation of secondary waste and with simultaneous copper deposition on the cathode is proposed. The kinetics regularities of copper electrodeposition and electrodissolution from pyrophosphate, tetrafluoroborate and mixed pyrophosphate-tetrafluoroborate electrolytes are studied. Electrochemical technologies for copper-containing waste treatment in pyrophosphate-tetrafluoroborate electrolytes to obtain marketable products are proposed. Technology of high-speed treatment to produce phosphorus-containing copper anodes and method of manufacturing of copper electrodes with mechanically strong and high electrochemically accessible surface area in the form of dendrite structures, that are well-coupled with substrate are proposed

  • MATERIALS

    • EFFECT OF ADHESIVE TYPE ON THE QUALITY PROPERTIES OF PARTICLEBOARD

      pg(s) 364-365

      The objective of the present study was to investigate the effect of adhesive type on physical and mechanical properties of particleboard. Three types of adhesives, urea-formaldehyde, melamine-urea formaldehyde adhesive, and acrylic adhesive, were used in the production of lab scale particleboards with three layers. The particleboards produced with the acrylic adhesive had the best physical and mechanical properties, followed by MUF adhesive, and UF adhesive, respectively. The lowest formaldehyde emission was observed for the acrylic bonded particleboards, followed by MUF, and UF adhesive bonded particleboards, respectively. Based on the findings obtained from the present study, the acrylic adhesive can be efficiently used in the production of particleboard.

    • MICROALLOYED STEEL UNDER TENSION AND BENDING CONDITION

      pg(s) 366-369

      The article deals with the influence of the loading rate in the interval from 1 to 1000 mm/min on the mechanical properties of drawing steel sheet, used for the manufacture of automotive parts, under tension and bending conditions. It describes the aspects of material characteristics under tension and bending conditions, while bending tests were made on notched specimens (a modified impact bending test). With an increasing strain rate up to the critical value, the resistance of material against strain increases and hence the yield point and the tensile strength increase, the deformation ability, the deformation homogeneity, the structure and the substructure after deformation, etc. Are changed. The paper presents knowledge that using a modified notch toughness test it is possible to achieve the formability characteristics corresponding to dynamic strain rates even under the static loading

    • EFFECT OF POWDER MODIFIERS ON STRUCTURE FORMATION OF IRON-CARBON ALLOYS

      pg(s) 370-372

      Effective modification not by expensive nano-powders but by relatively large ones (up to several microns) and capable to dissolve when entering into the melt and become additional crystallization centers at its start point was shown. That provides a metal structure refinement and, consequently, increases the whole complex of mechanical properties. The optimal process parameters of refractory compounds disperse powders modification were proposed.

    • EFFECT OF RARE-EARTH METALS (Dy, Tb, Sm, Nd) ON STRUCTURE AND MECHANICAL PROPERTIES OF THE Mg-Y-Gd-Zr SYSTEM ALLOYS

      pg(s) 373-375

      Kinetics of ageing, structure and the strength characteristics of the Mg-Y-Gd-Zr system alloys of compositions near to that of the IMV7-1(~5%Y, ~5%Gd, ~0.5%Zr, remainder Mg) alloy were studied. It was established, that alloying of the Mg-Y-Gd-Zr alloys with Dy, Tb, Sm, Nd results in strengthening of them at room and elevated temperatures both in homogenized and in aged states. Meanwhile, after addition of samarium or neodymium the ageing time needed for substantial strengthening becomes shorter, after addition of terbium it did not change actually and after addition of dysprosium it became longer. Therefore, the strengthening ageing for the Mg-Y-Gd-Zr alloys after addition of Nd, Sm or Dy requires certain corrections.