Machines. Technologies. Materials.
Vol. 12 (2018), Issue 1

Table of Contents

  • MACHINES

    • NEW STRUCTURE OF THE GANTRY CRANES LEVEL LUFFING JIB SYSTEM

      pg(s) 3-7

      A new construction of the gantry cranes level luffing jib system has been proposed. Its important operating characteristics has been studied. An optimization mathematical model of these structure is built. The parameters, optimization criteria and their limitations are defined. The optimization of construction is done using the Pareto optimization procedure in MATLAB. All parts and assembled units of the gantry cranes level luffing jib system have undergone optimization in practice. The results of the optimization study of the new design are compared with those of the traditional structure.

    • OPTIMAL SELECTION OF COMPONENTS FOR А HYDRAULIC EXCAVATOR SWINGING MECHANISM

      pg(s) 8-11

      In the present paper by the use of the Monte Carlo method, an optimal selection of components for a hydraulic excavator swinging mechanism has been made. Three objective functions are defined – the total mass of the components “hydraulic motor”, “gearbox”, “slewing bearing” and “small sprocket”, as well as the product of the total price and the total mass and the price of the same components. By computation of the objective function for multiple random combinations of the components and subsequent ranking of the objective function values, an optimal combination of the components is selected. A major advantage of the method is that it is suitable for computer realization and the number of required calculations is relatively small. Another advantage is that by the objective function value rankings close to the optimal additional combinations are obtained, which significantly extends the design possibilities.

    • ENERGY EFFICIENCY AND ENERGY POWER LOSSES OF THE TURBOGENERATOR STEAM TURBINE FROM LNG CARRIER PROPULSION SYSTEM

      pg(s) 12-15

      Turbo-generator (TG) steam turbine energy efficiency and energy power losses in a wide range of turbine loads were presented in this analysis. For TG steam turbine was investigated influence of steam specific entropy increment from the real (polytropic) steam expansion on energy power losses and energy efficiency. TG turbine energy power losses, during the all observed loads, were in the range from 646.1 kW to 685.5 kW. The most influenced parameter which defines change in TG turbine energy power losses is steam mass flow change, while for small steam mass flow changes, influence of steam specific entropy increment on steam turbine energy power losses is the most influential. Steam specific entropy incremental change can be used to estimate the change of TG steam turbine energy efficiency. Increase in steam specific entropy increment resulted with a decrease in TG turbine energy efficiency and vice versa. Analyzed steam turbine energy efficiency ranges from 53.84 % to 60.12 %, what is an expected range for low power steam turbines.

  • TECHNOLOGIES

    • THE DEVELOPMENT OF CALIBRATION FOR THE ROLLING BALLS OF DIAMETER 40 MM IN CONDITIONS OF JSC "SSGPO"

      pg(s) 16-18

      Paper presents a preliminary calculation of the calibration rolls for rolling balls with a diameter of 40 mm in a rolling mill JSC "SSGPO", which will be rolled from round workpieces with a diameter of 40 mm. The main elements of ball caliber are considered, their design dimensions are determined. It is established that the height of the flange varies linearly and the width of the spherical area increases during rolling.

    • EXTRACTION OF PRECIOUS METALS FROM A PYRITIC CONCENTRATE PRETREATED BY MICROBIAL OXIDATION

      pg(s) 19-20

      A sulphide flotation concentrate containing 15.2 g/t gold and 893 g/t silver finely disseminated in pyrite (4.1 % sulphidic sulphur in the concentrate) was treated by a two-stage process to recover these precious metals. Initially the concentrate was subjected to microbial oxidation by means of different acidophilic chemolithotrophic microorganisms (bacteria at 37 oC and archaea at 59 and 86 oC) to expose the precious metals encapsulated in the pyrite. The precious metals liberated in this way were then subjected to leaching by means of solutions containing different reagents (protein hydrolysate, thiosulphate, cyanide and some chemical oxidizers). The leaching was carried out in agitated reactors and up to 93.6 % of the gold and 80.8 % of the silver were solubilised in this way for 48 hours from a pulp density of 20 % at 57 oC.

    • ADVANCED HYDROGEN STORAGE TECHNOLOGIES

      pg(s) 21-23

      The development of ecological and efficient vehicles powered by hydrogen or electricity is one of the priorities of the automotive industry at the moment. These new propulsion systems should come as a replacement for the internal combustion engines, which use gasoline or diesel fuel and therefore produce toxic emissions. One of the problems, that hydrogen powered vehicles face, is hydrogen storage and that is the main topic of our paper Conventional technologies for hydrogen storage, like high pressure and cryogenic reservoirs, have many drawbacks in terms of compactness, mass (weight), efficiency and safety. In order to get over these problems, there have been many researches throughout the years in effort to develop new, commercially available technologies. The most advanced storage technologies today, are tanks filled with metal hydrides which absorb hydrogen by forming chemical bonds with it, and tanks filled with large contact surface materials that are able to adsorb hydrogen. In this paper we will present the requirements that these solutions have to fulfill, their current level of development and the expectations for future improvement and usage.

    • TECHNOLOGICAL LINE CONTROL VERIFIED ON HIL PLATFORM

      pg(s) 24-27

      The paper deals with the design and experimental verification of a new control structure with reference model for the tension control in the technological processing line the stability of which is derived on basis of the second Lyapunov method. The properties of the proposed controller were verified by experimental measurement on a new concept of hardware-in-the-loop (HIL) simulation platform based on programmable logic controllers (PLC). The experimental measurements confirmed that the proposed control structure is robust over a wide range of controlled system significant parameters changes together with invariance and desired dynamics prescribed by the reference model.

    • FUNCTIONAL AREAS AND ARCHITECTURAL FRAMEWORK FOR THE MANAGEMENT OF THE ELECTRON BEAM WELDING INSTALATION

      pg(s) 28-30

      Abstract: Management is the process of processing the information aiming decision making to resolve problem or to achieve the target. High advanced automated processes, including the vacuum system with pump and pressure control, management of the cooling system, management of the manipulator, high voltage control and emission current, the control of the electron beam movement and its characteristics, as well as computer-based automatic control ofthe beam power distribution, must be integrated on the basis of the use of systems for operational management of production. The present work presents the hierarchical structure and architectural framework for the management of an installation for electron beam welding, evaporation and surface modification.

  • MATERIALS

    • THE RESEARCH PROCESS OF ACTIVE DIELECTRICS: SYSTEM INTERCONNECTIONS

      pg(s) 31-32

      Ferroelectric thin films are widely used in devices of micro- and nanoelectronics. In particular, their unique properties (high values of relative permittivity, hysteresis loop, close to rectangular) are connected with the presence of a phase transition leading to a change of the functional dependencies form between the material parameters at temperatures below and above the phase transition temperature. Depending on the purposes of materials research consisting in the analysis of their properties or the materials synthesis with specified characteristics, two tasks can be solved: materials analysis ; controlled synthesis of a material with specified properties.The authors considered the generalized structure of the study process of ferroelectric materials; the interconnection of the parameters of active dielectrics was analyzed. It made it possible to optimize the process of studying the materials used in elements of functional electronics.

    • EFFECT OF BORONIZING PARAMETERS AND MATRIX STRUCTURES ON THE WEAR PROPERTY OF DUCTILE IRON

      pg(s) 33-36

      In this study, the effects of matrix structure (pearlitic, tempered martensitic, lower ausferritic, and upper ausferritic), boronizing temperature (800, 825, and 850°C) and time (3, 4.5 and 6 hours) on the wear behaviour of Cu-Ni-Mo alloyed ductile iron were investigated. Wear tests were performed on ball-on-disc type wear tester under the load of 6.8 N, at sliding speed of 6.5 mm/s, at room temperature and dry sliding conditions. The mass losses were measured after wear tests and the friction coefficients were obtained during wear tests. The hardnesses and thicknesses of boride layers, microstructures and worn surface examinations (SEM) of the matrix structures and borided layers were performed. The surface hardnesses of borided samples were obtained three or four times more than that of the matrix structures. The best wear performance was observed for the sample borided at 850°C for 6 h. The mass loss of this boronizing condition is 0,2 mg and this value is nine times less compared with that of the as-cast pearlitic structure.

    • EFFECTS OF MECHANOCHEMICAL TREATMENT OF ThO2 WITH UO3 AND CеO2

      pg(s) 37-40

      The paper presents the effects of the mechanochemical activation of ThO2-UO3 and ThO2-CeO2 mixtures in air and (for ThO2-UO3) in suspension in H2O or CHCl3. Planetary ball mill (Pulverisette 5, Fritch) with stainless steel triboreactors and milling balls from the same materials are used. Milling for 5 h of the ThO2-UO3 mixture does not affect significantly the crystal structure of the ThO2 but leads to amorphization of UO3, sharp decrease of its crystallites size and increase of the ionic character of the U-O bond. Storage of the activated product (2 months at room temperature) or heating (3 h, 165 oC) leads to partial relaxation of the UO3 crystal structure. The X-ray diffraction data does not give proves for formation of ThO2-UO3 solid solution.

      Formation of solid solution Ce0.6Th0.4O2 accompanied with some amount of amorphisized ThO2, is established as a result of co-milling at the same conditions of the mixture ThO2 – CeO2 with a mole ratio 1. XRD-determined lattice parameter (5.4804(9) Å) and crystallites size (14 nm) of the obtained solid solution are in satisfactory agreement with literature data for the same product obtained via wet chemistry route.

    • PECULIARITIES OF Fe POWDER CONSOLIDATION IN CONDITIONS OF SPARKPLASMA SINTERING

      pg(s) 41-44

      Theoretical and experimental data on the impact of heating rate during spark-plasma sintering on densification kinetics, grain size and capillary pressure in powder compacts, based on Fe, are given. It is found out, that an increase of heating rate in range from 10 °C/s to 20 °C/s leads to acceleration of process of obtainment of non-porous compacts and decrease of structure grain size.