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Sex helps the valve to open.
2.2 hydraulic control Check Valve hydraulic control check valve is also called one-way lock valve. A hydraulic one-way valve is added to the hydraulic system, and the tightness of the closing of the cone valve is utilized to keep the oil path for a long time.
The hydraulic control check valve is mainly used for the front and rear columns on the hydraulic support.
When coal mining, the hydraulic support column piston cavity needs to maintain high pressure for a long time to support the top plate, the time may reach several days, which requires the seal of the hydraulic control check valve must be good. The hydraulic control check valve is also used on other bearing components of the hydraulic support due to customer requirements, force of the large inclination hydraulic support.
The following points should be noted when selecting the hydraulic control check valve: (1) Select the hydraulic control check valve according to its position in the hydraulic system or the flow resistance (back pressure) after the oil chamber is reversed. Reasonable selection of the hydraulic control check valve not only improves the reliability of the system work, but also can achieve considerable economic benefits; (2) pay attention to whether the control pressure meets the requirements of reverse opening.
It is guaranteed that the hydraulic control check valve has sufficient control pressure in the hydraulic system, and it is absolutely not allowed to control the pressure loss. If the control of the pilot operated check valve leads to the autonomous system, the influence of the change in the pressure of the main system on the control of the oil passage pressure should be considered to prevent malfunction.
2.3 One-way lock In the hydraulic system, the one-way lock is an important component of the hydraulic support, with simple structure and stable performance. The one-way lock allows the actuator to stop at any position and provide a reliable locking action to avoid possible displacements under the influence of various factors.
In the hydraulic system, it is mainly used to control the tail beam jack, the front beam column and the telescopic beam jack on the hydraulic support, and is reliably locked to prevent backlash and ensure the stroke.
2.4 two-way lock two-way lock, also known as hydraulic control two-way lock. It is a device that controls the entry and exit of liquid in the branch pipe system or working chamber in the hydraulic system, and realizes one-way sealing of the pressure liquid in the system or working chamber, and opens under constant pressure. The inlet and outlet lines of an actuator are often controlled by each other. It allows the actuator to be reliably locked after stopping at any position, thereby preventing possible displacement.
In the hydraulic system, it is mainly used to control the guard on the hydraulic support (the device for supporting the coal face on the working face, preventing the front part of the bracket from falling off the meteorite and coal into the working space), and is reliably locked to prevent back-off. . According to the force of the guard jack, the two-way lock should be installed with a safety valve and used together.
3 Application examples This paper takes a coal mine in Shanxi as an example. The coal mine adopts fully mechanized longwall fully mechanized top coal caving mining. The coal seam depth is 180m, the coal seam thickness is 10.3~15.8m, the average thickness is 11.8m, and the machine rice is 3.3. m, the working face length is 120m (the distance from the inner coal wall of the groove). The working face inclination angle is <15., and the hardness is 2~4. The roof is mainly composed of old roof, fine sandstone and medium coarse sandstone with a thickness of 4~6m. The bottom plate is sandy mudstone with hardness of 6~7. The mine is a low gas mine with a small amount of water on the working surface and no corrosive water.
Based on the geological conditions of the coal mine, the hydraulic support is selected as the ZF7500/18/35 top coal hydraulic support and the ZFG8000/21/35H top coal transition hydraulic support. The valve usage of the hydraulic support is shown in Table 1.
Table 1 valve application components apply hydraulic check valve, the rear column maintains the column high pressure to support the top plate one-way lock jack, the front beam jack, the telescopic beam jack stop at any position; avoid the displacement of the two-way lock protector jack any position stop; Avoid displacement safety valve column, guard jack, tail beam jack to ensure that the load bearing components are not overloaded. 4 Conclusion This article takes a four-column support shield hydraulic bracket as an example, for safety valve, one-way lock, hydraulic check valve and two-way lock The working principle, application position and function of the hydraulic system of the hydraulic support were studied.
This paper proposes that when selecting the valve of the hydraulic support, comprehensive consideration of the geological conditions, economic cost, service life and other conditions of the coal mine ensures the support capacity of the hydraulic support and improves the coal mining efficiency.
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