Search

В настоящее время определение мощности выброса твердых взвешенных веществ с единицы площади поверхности техногенного массива при различных параметрах ветрового потока описано недостаточно. Анализ мирового опыта исследователей показал, что существующие лабораторные установки обладают различными конструктивными особенностями, не позволяющими корректно определить массу взметаемой и переносимой пыли. На основании результатов анализа разработана концепция инновационной лабораторной установки для исследования пылящих поверхностей. Она учитывает влияние аэродинамичеких теней, детурбулизацию искусственно создаваемого потока воздуха, возможность регулирования не только скоростного режима потока, но и создания разряжения или возмущения в области размещения образцов, а также формирования определенного угла атаки ветрового потока относительно поверхности. В концепции заложена возможность определения объемов выброса пыли по значениям потерянных масс пыли в образце и по значениям концентраций пыли в выходящем потоке. Проведен расчет основных базовых элементов установки с применением программного пакета ANSYS FLUENT. Разработана и рассчитана модель и компоновка аэродинамической трубы, определены основные геометрические параметры и функциональные элементы для возможности использования в научной работе. Для практического использования эмпирического показателя шероховатости подстилающей поверхности рекомендованы его значения в широких пределах – от нуля для водной поверхности до 0,44 для крупных городов с высокими зданиями и небоскребами.

The results of tests for resistance to abrasive wear on highly abrasive hard rock white electrocorundum are presented. The main material of fast-wearing elements of mining and processing equipment-110G13L steel (Gadfield steel) in comparison with other 9 grades of steel and cast iron, including specially developed wear-resistant foreign steels such as Hardox and Miiluks, is analyzed. The studies were carried out using an experimental stand for studying the material wearing process. On the stand the sample was fixed in a holding device and, after being brought into contact with the abrasive, it was rotated under a constant load. As a result of the experiments, it was confirmed that the order of placement of the tested materials in terms of increasing wear resistance coincides with their placement in terms of increasing hardness. At the same time, the wear resistance of the most resistant material – U8A steel after quenching – is about 4 times higher than this indicator for the least resistant components – low-carbon steel 25L, including gray and high-strength cast iron SCH21, VCH35. The wear resistance of 110G13L steel, as well as 65G, U8 steels in the hardened state, is from 1.5 to 2 times higher than that of foreign steels M400, H450, M500, H500. The results of the conducted studies allow us to evaluate the analyzed materials on the basis of their wear resistance and hardness indicators on the feasibility of using them in the manufacture of fast-wearing parts of mining equipment. Based on the research data, it seems promising to develop new ways to increase the wear resistance of domestic steel, including 110G13L steel traditionally used in mining.

This work presents results of experimental researches of influence of various high-temperature thermomechanical treatment (HTMT) modes in 35KhGSA steel – material applied in rock-destroying cutters – on hardness and wear rate for the most common abrasive rock in mining operations – sandstone. It has been found out that HTMT leads to increase of steel hardness and reduction of wear rate compared to heat treatment applied at manufacture of cutters. The maximal increase of hardness (by 23%) and reduction of wear rate (by 38%) corresponds to the mode of distortion accumulation of ~1,5 at 900 °С at water quenching and tempering at 230 °C. A conclusion that thermomechanical treatment is an effective way to increase the wear resistance of steels applied in the conditions of abrasion wear has been drawn.

The results of experiments on determination of the cylindrical part mass loss of the cone-shaped strikers made of 38XM (AISI P20), У8 (AISI W1-A), and X12MФA (AISI D2) steels, which have been subjected to heat treatment applied by the striking tools manufacturers, and additional cold treatment, with their friction and abrasive wear on granite, are presented. It was found that the strikers made of steel X12MФA with all types of heat treatment show the greatest wear resistance under the wear conditions (static conditions), while the strikers made of 38XM have the lowest wear resistance. Cryogenic treatment and, to a lesser extent, cold treatment increase the wear resistance of all materials. The comparison of set values of wear resistance I st and hardness HV of the strikers, as well as the analysis of their microstructure allows to conclude that wear resistance of a tool depends not only on its hardness, but also on the type, volume, shape of carbides forming the structure of material used for tool manufacturing. For this reason, after the cryogenic treatment, the tool made of X12MФA steel shows the greatest wear resistance, because its material has the highest content of carbon (∼1.5%) and alloying elements (∼13%), which provides up to 10.8% increase in the number of fine carbide particles in its structure, that ensure wear resistance increase, after the cold treatment. The results obtained for I st are compared with the earlier obtained data on wear resistance of the same striker at striking upon granite (in dynamic conditions). The conclusion about similarity of the wear mechanisms of the analyzed strikers in dynamic and static conditions is made.

The causes of failure of the bucket teeth of the excavator during excavations in rocks are analyzed in the article. It is shown that the most typical cause of failure of bucket teeth is wear of teeth. The wear with soft rocks (less than 1100 HV) which hardness is lower than the hardness of steel in the cold-work hardened state, a preliminary cold-work hardening can essentially (up to 10 times) increase the material wear resistance. The wear with rocks, having greater hardness with hardness of ~1250 HV, the cold-work hardening do not lead to increase of the Hadfield steel wear resistance.

The experimental studies results of the mechanical and thermo-mechanical treatment influence of wear resistance of excavator bucket tooth materials and rotary cutting tool are presented in this article. Experiments on abrasion in different rocks were investigated. In the example of 110G13L steel (Hadfield steel), it was shown that mechanical strengthening (cold hardening) is an effective way to improve wear resistance of machine parts working in abrasive environments. It was revealed that if the hardness of abrasive materials is lower than the hardness of cold hardening steel, wear resistance may increase by 10 times and if the hardness of abrasive materials is higher than the hardness of steel with cold hardening, it does not influence wear resistance. It was found that the high-temperature thermo-mechanical treatment of 30KhGSA steel increases its hardness (by 23%) and wear resistance (by 38%) by comparing with the same steel after hardening. It was concluded that the advisable use one of these methods depends on rock hardness.