MATHEMATICAL MODELING AND OPTIMIZATION OF HEAT PROCESSING OF SQUARE CROSS SECTION STEEL BAR ON THE TECHNOLOGICAL LINE “CONTINUOUS CASTING MACHINE - TUNNEL THERMOS - HEATING FURNACE”

The PAO Severstal continuous casting machine (CCM) casts square section 100´100 and 150´150 mm billets that after the gas cutting have average temperature 1000-1100 °С. Then billets CCM, transported to the section mill shop, should be placed into a tunnel thermos for preserving their sensible heat and temperature leveling along their section. In this case hot billets are loadedin the heating furnaces, and heating of the billets to required temperature before rolling can be accelerated several times, increasing capacity of the heating furnace and diminishing the specific fuel consumption. The authors present the mathematical model that allows evaluating the heat state of a square section billet on the technological line “CCM - thermos - heating furnace”. The results of numerical simulation of the billet heat state at optimal modes of heat treatment in the thermos and the heating furnace are given.

CFD SIMULATION OF TEMPERATURE REGIMES OF THE COMBUSTION ZONE OF STABILIZER-TYPE BURNERS WITH ASYMMETRIC FUEL SUPPLY

The results of computer simulation of the heat state of the combustion zone and the burnup rate of fuel for stabilizer burners with asymmetric fuel distribution are presented. The features of temperature fields in this zone that are characteristic of the conditions under study are revealed. The analysis of these features in the aspect of their conditionality by the two-stage combustion of fuel gas is carried out.

Effect of wear-resistant coatings on heat state of twist drills

The effect of wear-resistant coatings on the thermal state of twist drills is studied. The effect of wear-resistant coatings on the distribution of temperature fields in the cutting wedge and the distribution of heat generation intensity along the main, minor cutting edges and transverse edge of the drill is shown. The requirements for coatings for the drilling operation of workpieces are formulated and the architecture of the multilayer coating is formed.

ELECTRON-BEAM MELTING OF INGOTS OF TiAl SYSTEM INTERMETALLICS

Performance of scientific-technical researches at the E. O. Paton Electric Welding Institute of the NAS of Ukraine have been directed on development of technology for manufacture of titanium aluminide –based alloys using the method of electron-beam melting (EBM). The mathematical models of heat state and evaporation of alloying elements in EBM were developed. The results of calculations of heat state using the mathematical model allowed determining a dependence of depth of liquid pool on different melting rates. The mathematical models of processes of evaporation in EBM of titanium aluminide ingots were used for plotting the nomograms, which help to determine the necessary content of alloying element of the alloy in the initial charge for acquiring the necessary concentration of this element in ingot at set technological parameters of melting. In scopes of designed mathematical models there were investigated different technological modes of electron-beam melting of ingots based on titanium aluminide. The optimum EBM modes, at which a solidification front approaches to flat, were determined. At that, more uniform distribution of the additives on ingot section and volume is provided as well as level of stressed state is reduced. The works were carried out on manufacture of titanium aluminide based-ingots with addition of refractory as well as volatile alloying elements. Composition and structure of produced ingots were examined. It is shown that electron-beam melting allows getting chemically homogeneous ingots based on titanium aluminide and is a perspective method for production of such class materials.

Minimization of heat state for friction lining of truck brake mechanism

A theoretical analysis to determine a microgeometry of friction surface for the drum—lining pair is carried out. The sought-for microgeometry provides a uniform temperature distribution on the contact surface. The model of a rough friction surface is used. A closed system of algebraic equations is constructed. This system allows the solution of the optimal design problem for the drum- lining friction pair of the truck brake mechanism depending on geometric and mechanical characteristics of the pair elements. Keywords friction pair, drum, lining, wear, optimal microgeometry, uniform temperature distribution

CFD SIMULATION OF TEMPERATURE REGIMES OF THE COMBUSTION ZONE OF STABILIZER-TYPE BURNERS WITH ASYMMETRIC FUEL SUPPLY

The results of computer simulation of the heat state of the combustion zone and the burnup rate of fuel for stabilizer burners with asymmetric fuel distribution are presented. The features of temperature fields in this zone that are characteristic of the conditions under study are revealed. The analysis of these features in the aspect of their conditionality by the two-stage combustion of fuel gas is carried out.

Efficiency of special cooling liquid on thermal state of athletes at high temperatures

The article presents results of evaluating efficiency of special cooling liquid influence on heat state of athletes at high temperatures. The study covered 7 male athletes of cyclic sports, with sport rank at least 1 adult, average age 19.29±1.80 years. All the athletes underwent double examination including: anamnesis and complaints records, doctor’s examination, subjective evaluation of heat sensations, weight measurements, thermometry (tympanic, sublingual, rectal and skin (in 5 points)), ergospirometric stress testing. Changes in the athletes’ heat state were evaluated via dynamics of weighted average skin temperature and rectal temperature. Moreover, subjective evaluation of heat sensations was considered. Efficiency of the cooling liquid was assessed via dynamics of exercises performance time, maximal oxygen consumption and anaerobic metabolism threshold. The cooling liquid use appeared to be expedientin sport teams of summer sports for specific exertion after individual tests for adverse allergic reactions.

Measurement technique and results of evaluating influence of heating microclimate on skin surface temperature in workers engaged into oil thermal mining

The study was aimed to refine a method evaluating level and dynamics of skin surface temperature as an indicator of heat state in a worker exposed to intermittent influence of workplace ambient high temperatures during a working shift. The measurement technique was automated continuous detection with registration of parameters every 5 seconds and the data backup to memory card. Findings are that actual scenarios of heat load on the workers significantly differ from the calculated ones. Mathematic models of relationships between air temperature and skin temperature were obtained and helped to play various scenarios of the workers’ presence in “heat” zones and evaluate them according to criteria of weighted average and maximal skin temperature. Results are thatoCcupational conditions of workers engaged into underground oil thermal mining necessitate specification and implementation of preventive measures and improved regulatory support, concerning creation of safe microclimate parameters.