Key Engineering Materials Vol. 685

Abstract: The results of strength and stiffness calculations of gun drills with steel and cemented carbide stems are presented. Four cross-sections of gun drills are examined and recommendation for selection of proper shape in terms of strength and stiffness is given. Finite element modeling of gun drills shown that the highest stress concentration is at the bottom of the V-shaped flute in the middle of the length of the stem. Gun drill testing under production conditions confirmed the results of finite element modeling.

Abstract: Present paper is an attempt to illustrate a specific character of gas combustion and thermo-electrical processes in small-sized power energy-supply devices with thermoelectric methods of heat conversion. The efficiency of the heat conversion into electricity by using of thermo-elements embedded in the solid walls is estimated for a system with heat regeneration by means of the heat conductivity of the solid elements.

Abstract: The problem of designing advanced computing systems of integrated modular avionics is considered in this paper. A unified topology of internal network based on SpaceWire channels and options for its application for a variety of onboard implementations are proposed. Equivalent reliability scheme of each special structure is provided and the fail-safe performance probability of each structure is analyzed.

Abstract: The overview of penetrant testing quality control is considered. Disadvantages of methods of manufacturing metal check samples are identify, e.g. the implementation of several defects of different sensitivity classes on a single sample. The paper addresses the technology of application of universal nonmetallic reference test blocks containing several artificially-induced defects in the form of cracks of different sensitivity classes for liquid penetrant testing to evaluate the performance of liquid penetrant testing.

Abstract: This work describes methods of designing grinding cycles and controlling them. We demonstrate that using modern equipment allows programming stepless feed change during whole finishing cycle, giving opportunity to organize more complex high productive cycles of abrasive treatment. Taking this fact into account we suggest algorithm of situation feed correction for forming effective cycle of round grinding with radial feed, allowing maintaining process productiveness and preventing thermal defects.

Abstract: The paper presents constructive scheme, the mathematical model and schematic diagram of the hydraulic rotary control valve of the pneumohydraulic impact unit. Detailed analysis of the mathematical model was made for the purpose to create modes of the movement conducive to improving the work of pneumohydraulic impact unit at the point of switching. The results of mathematical modeling (schematic diagram of matlab) are given.

Abstract: The analysis of geometry of abrasive grains on macrogeometrical and microgeometrical indicators is carried out; charts of distribution of these indicators are submitted. The research technique based on application of photometry for obtaining digital images of abrasive grains is described. On the basis of this method we have established that abrasive grains can be devided into following form types: isometric, beam-type, and laminar. Grains sharpening and peaks rounding radii R in samples scanning plane were investigated in order to analyse abrasive grains microgeometry. Statistic analysis provided following results: average grain sharpening angle is within limits of 85° ≤ β ≤ 90°; average grain peak rounding radius is equal to 0.2 ≤ R ≤ 0.4 mm.

Abstract: The main goal of the investigation is to determine key technological parameters, necessary for producing required curvature of sheets up to 4000 mm in width with the required mechanical properties. Investigation into dynamics of the process' main technological parameters allowed it to define its three characteristic stages: asymmetric rolling, asymmetric rolling in combination with initial unsettled plastic bending, and asymmetric rolling combined with settled plastic bending. It was found out that the intensity of the deformations changes unevenly, depending on the height of the deformation zone, on all three stages, with its highest value being in the lower part of the sheet, and with the lowest value being in its center. In the second stage, the intensity of the deformation abruptly increases, and a significant asymmetry on the sheet thickness occurs. In the third stage, the non-uniformity of the intensity deformations fields decreases. Similar results can be also observed for stress intensities. Casings on two converters were produced and installed in the oxygen-converter plant.

Abstract: The technology of microalloying zinc melt by nickel is widely used to control the thickness of the zinc coating when the machine steels are subject to hot-dip galvanization. However, in some cases inclusions of Ni-Zn-Fe dross are formed on surface of the products, which leads to their deterioration. The aim of this work is to investigate the microstructure, mechanism of formation and elemental composition of this dross. Conditions for the formation of different phases in the coating were analyzed using Ni-Zn-Fe ternary diagram. It was found that Ni-Zn-Fe dross is a ζ-phase containing about 0.5 at. % nickel and isomorphic with FeZn13-phase. The main reasons for the formation of Ni-Zn-Fe dross are Zn-Fe contamination in the melt, the excess nickel concentration (more than 0.06 at.%), and the irregular nickel concentration in the melt. Methods for preventing this type of defects in hot-dip galvanization have been proposed.

Abstract: The study results of the influence research of reduction ratio in cold rolling on the anisotropy of mechanical properties of sheets from aluminum alloy 8011A are shown in this article. It was determined that the effect of cold rolling on various mechanical properties is different. However, for all characteristics were usual to change the distribution mode and variance reduction in sheet plane during the high ratios of deformation. At the 85-90% reduction ratio it is observed the leveling of mechanical properties in sheet plane.