The article evaluates the failure rate of devices in the Mechanical Processing Plant using a traditional quality tool, the Pareto-Lorenzo diagram. A comparative analysis of failure rates was performed, recorded in repair, inspection and maintenance card. Then, changes were proposed in order to reduce failure rates and earlier detection of equipment malfunctions. In order to analyze the failure rate of grain washer equipment during thick coal preparation process, one quality management tools was used - the Pareto-Lorenzo diagram. In this case, it is important to assess the mechanical failure of devices, and demonstrating which devices generate most repairs. Based on materials made available by the mine, such as: Repair, inspection and maintenance cards, Device cards, DTR documentation. Quantitative and qualitative assessment the most frequently occurring mechanical failures during operation of devices in process enrichment of coarse sizes was carried out. An attempt was made to assess failure rate of devices on a grain washer. A comparative analysis of failure rates in 2015-2017 recorded in the repair, inspection and maintenance card was carried out. Then, changes were proposed to stand, in order reduce failure rates, and earlier detection equipment malfunctions.
The current trends of production of casts are directed towards production of components disposing of higher accuracy, increased quality of surface and homogenous structure. In case of a thin-walled cast the development of speed of pressing and of pressure was observed inside the mould cavity during pressure die casting of ferrous alloys. In case of die casting of ferrous alloys the attention was paid to life service of a pressing piston and of a filling chamber. The optimal temperature of the steel casting ranges from 1600 to 1750°C and optimal mould temperature ranged from 220 to 260°C. The residues having occurred in gates reached the hardness of 38 HRC and in case of casts the value was of 45 HRC. Influence of acting of resistance pressure on the thin-walled casts only minimally. With the increasing resistance pressure the structure becomes more fine-grained and along with the increasing thickness of the wall the influence of the resistance pressure increases as well. Technology of pressure die casting of iron alloys can be compared with the pressure die casting technology of aluminium alloys. As standard, for pressure die casting the cast irons with carbon content of lower than 3% are recommended.
This article presents the results of noise tests, measurements and proposals of solutions that have an impact for reducing noise at one of the Jastrzębska Spółka Węglowa S.A. mines. All units and workstations at the mechanical coal processing plant were tested. Coal enrichment, aimed at adjusting its quality parameters to the requirements of various customers, is considered as a stage of mineral resources management. The adaptation of the quality of commercial coal products to the needs of specific customers consists in removing useless components from the excavated material. The processes of coal processing are carried out on various machines, the power of which reaches several dozen kilowatts. The energy of these machines, in addition to the useful power, is converted into heat, friction and noise. From the energy point of view, noise is not important, but it is very harmful to employees. The issue of noise pollution, although very dangerous to employees’ health, is often underestimated. Due to the subjective perception of noise, it is not possible to determine the risk without proper research. The aim of this study was to determine where the noise standards are exceeded. The next step was to propose specific solutions to reduce the impacts of noise on health and work comfort.
The joint research of scientists of two countries deals with cylindrical and surface grinding with abrasive wheels of heat-resistant steel Inconel 625 (KhN77TYu GOST 5632 – 72 Russian Federation standard), (analogues include Hastalloy, N07080, Alloy 80A, Nimonic 80A, 2.4952 ASTM B637/ASME SB637, UNS N07080). The article shows the results of studies of the features of high-temperature steel during grinding with a fastened abrasive. The results of experiments are given to determine the optimal characteristics of grinding wheels, grinding modes, cooling-lubricant fluids. Experimental data about geometric accuracy, surface roughness, resistance of wheels are demonstrated as well. The ways to prevent from defects during cylindrical and surface grinding of high-strength steel are proposed. The recommendations to increase the tool resistance and output of the process are given.
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