Abstract.A steady increase in coal extraction in Russian Federation and worldwide results from objective causes of natural resources availability and development of advanced coal processing technologies. In the context of the long-standing economic crisis, considerable investments in coal industry are not to be expected. Consequently, the reserve for extraction growth lies in increasing productivity of the key equipment applied in Kuzbass coal pits. The production data analysis revealed that the presented excavators working capacity does not depend on the bucket volume and the cycle time. It is hereby specified that working capacity is primarily dependent on the actual operation cycle time. As it is demonstrated, the key reserve for increasing the working capacity consists in elevating efficiency of actual performance time use.
Abstract. Coal extraction in Russian Federation increases by 3…4 %. This tendency will remain in the nearest 10…15 years. Opencast mining makes (70...72)% from the total extraction in the country. Though analysis shows that investments in coal mining within the last 25 years were insignificant. In these conditions the priority area for coal production cost reduction and increasing productivity of opencast coal mines is optimization of the main technological equipment (excavator park) maintenance system. The article shows that current system of scheduled preventive repair is not efficient and requires to be changed to the system of repair works due to actual state of the equipment.
Abstract.The article tells about forming a new concept of scheduled preventive repair system of the equipment at coal mining enterprises, based on the use of modern non-destructive evaluation methods. The approach to the solution for this task is based on the system-oriented analysis of the regulatory documentation, non-destructive evaluation methods and means, experimental studies with compilation of statistics and subsequent graphoanalytical analysis. The main result of the work is a feasible explanation of using non-destructive evaluation methods within the current scheduled preventive repair system, their high efficiency and the potential of gradual transition to condition-based maintenance. In practice wide use of nondestructive evaluation means will allow to reduce significantly the number of equipment failures and to repair only the nodes in pre-accident condition. Considering the import phase-out policy, the solution for this task will allow to adapt the SPR system to Russian market economy conditions and give the opportunity of commercial move by reducing the expenses for maintenance of Russian-made and imported equipment.
Supporting metal structures of large dump trucks at open cast coal mines function under exposure to alternating cyclic load. Fatigue cracks that appear there require timely maintenance welding. Organization of repair processes is multivariant; it can be performed either by the enterprise (open cast coal mine) efforts or by special repair units. An industrial experiment carried out at Permyakovskiy and Prokopyevskiy open cast coal mines in Kuzbass has shown that type of large dump trucks’ repair works organization influences significantly process efficiency. Repair welding by enterprise efforts is the most non-productive compared to other types of repair process organization. Its specific rate is 37 per cent lower than in comparison with unstructured welding and 2.2 times lower in comparison with structured metal sheet replacement and structured welding. Structuring repair processes allows to increase their efficiency by 30...40 per cent on average. Structured replacement of the spring plate is the most productive type of metal structure repair process organization. Comparison of maintenance measurement results in accordance with Unified Norms and Prices collected book with the results obtained from the industrial experiment showed that calculation methods give underestimated values of repair processes’ specific rate.
Kuzbass opencast coal mines use foreign produced excavators as basic equipment. Capital repair of these excavators involves complete replacement of all tooth wheel gearing in reduction gear boxes after 2~3 years of work (depending on operating time). The cost of this replacement is practically equal to the cost of new gear boxes. To minimize repair costs and extend service life of gear-tooth systems in gear boxes a methodology for monitoring technical state of gear boxes in imported mining equipment was developed. It allows to obtain reliable information about the level and significance of in-service defects in their elements. The research showed that the most reliable methods of control are visual and dimensional test (67%) and fluorescent-magnetic inspection (32%), and used together these two methods allow to detect up to 100% of significant defects. The most significant among service defects in typical elements of gearing systems are single and multiple cracks.
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