Powered roof support is equipped with a hydraulic control system to ensure its required load capacity. The main problem arising from powered roof support during exploitation is providing the necessary load capacity. A decrease in load capacity is mainly associated with internal and external leakage in the cylinders, mainly in the hydraulic props. The hydraulic prop’s role is to ensure stability for the powered roof support. A special double block with an additional pressure boost was developed to counter the props’ leakage phenomenon. Pressure loss is replenished based on the solution proposed here. For this purpose, bench tests were commenced, in which a prop with an internal leakage was used. The research included the analysis of the operation of a boosted double block. The results allowed us to assess whether the developed solution can be the subject of further research conducted in real conditions.
A mechanical support in a longwall complex requires proper supervision and control of operating parameters because it is responsible for the safety of machines and workers. Its main functions are to protect the excavation against the adverse effects of rock mass and to move it along with the operational progress of the shearer and the scraper conveyor. In the era of Industry 4.0 as well as green economy and sustainable development, the development of machines and devices included in the longwall complex is an important area of invention. When it comes to the mechanical support included in the longwall complex, the authors propose changes to the hydraulic control system. The main purpose of the work was to develop a system that can automatically expand the legs of the powered support. Tests were carried out under real conditions while equipping the support section with a prototypical hydraulic system and with a system monitoring the correct operation of the prototype. This article presents the development of a prototypical installation under real conditions for testing on a longwall. The innovative solution proposed by the authors consisted of introducing a prototypical double valve block into the hydraulic system of the housing, which enables the function of automatic section expansion. The authors proposed a solution aimed at shortening the work time of the powered-support-section operator. The research results made it possible to evaluate the usefulness of the proposed solution. This type of solution can be considered technical support in the process of coal mining in an underground mine. Analysis presented in this paper, along with results from research conducted and its conclusions, can be of practical help to enclosure users to improve reliability and achieve optimal performance.
Информация о статьеПринята 8 мая 2020 г.
The hydraulic system of a powered roof support performs two functions. The first function is to control the powered roof support in the extraction wall. The second function is to protect against adverse overloads resulting from rock mass pressing directly on the powered roof support. This damaging phenomenon is prevented by the protection of the powered roof support, with a safety valve built into the hydraulic system or directly into the prop. However, the third function proposed by the authors based on the research results is to minimize leaks. These leaks usually develop in the props or in the hydraulic system. The authors propose implementing changes to the hydraulic system for this purpose. The change consists of replacing the existing support block with a double block with charging. Tests were carried out in real conditions, that is, a mining wall. Tests in the mining wall were carried out on the powered roof support’s leaking prop. As a result of charging, the actual load capacity of the prop increased by about 10–50% in relation to the load capacity before charging. The use of a double block with charging ensured that the pressure in the under-piston space of the prop was maintained at a minimum of 250 bar. The results allowed us to determine the usefulness of the proposed solution and eliminate its disadvantages—the designated direction of research and development on the powered roof support allowed us to expand its functionality by minimizing leaks.
Effectiveness of a powered roof support significantly impacts on the efficiency and safety of a mining process. The main element of the support is a hydraulic leg which transfers loads imposed by the rock mass. One of the basic issues occurring during the extraction process are internal and external leaks of hydraulic systems. A new support system was designed to limit and later eliminate the consequences of such leaks. Its main component is a valve block equipped with two independent check valves. This solution allows to maintain high pressure in both chambers of a leg despite leaks. The article discusses the developed solution and presents preliminary results of bench tests of a leg equipped with the new block and loaded dynamically. The results are promising, and the tested block fulfils its task by maintaining the working pressure in the leg during load.
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