Improvement of hydraulic fine-tuning system for medium plate mill
1,Guarantee system cleanliness
Solid particulate contaminants are the main cause of valve plugs, wear and seal damage. The hydraulic fine-tuning system of plate mill is a high-pressure, high-flow servo control system that is very sensitive to solid particle contaminants. In particular, the high-flow, high-response MOOG servo valve has a radial clearance of 2 to 5 μm, and its filtration accuracy must be superior to that of NAS6.
Add a fuel filter auxiliary fuel tank to filter and store the reserve oil during refueling.
The accuracy of the pressure filter element in front of the servo valve is increased from the original 10μm to 5μm.
All filters are replaced with filter cartridges with high dirt holding capacity and high filtration ratio to extend the filter replacement cycle and reduce the possible contamination of the filter.
When replacing hydraulic components, clean kerosene must be used to clean new components, tooling tools and joints, servo valves, pressure sensors, etc. Precision components must also be cleaned with precision electrical cleaning agents to prevent new contaminants from being introduced.
When repairing or installing pipelines and joints, mechanical cutting and cutting, sub-arc welding and normal surfacing should be used to prevent the welding slag welding into the pipe. It is strictly forbidden to cut welding and strictly implement hydraulic system piping installation and flushing. Relevant standards.
Before installing the servo valve, first install the flushing plate to flush the system for 3~4h.
2,Reduce the impact vibration of the system
The hydraulic fine-tuning system of the plate mill is a high-pressure, high-flow servo system. The servo valve responds frequently, the hydraulic cylinder liquid column is quickly adjusted, and the flow impact is large.
Check the accumulator pressure of the accumulator regularly. In the hydraulic station, the accumulator acts as an auxiliary energy source. The flow rate of the accumulator should be greater than the difference between the maximum flow rate of the system and the working flow of the pump. The inflation pressure is about 0.80 times the working pressure of the system. Before the servo valve, the pressure shock is set. The accumulator has an inflation pressure of about 0.85 times the working pressure of the system; on the main oil return pipe, an accumulator that absorbs the flow pulsation is provided, and the inflation pressure is about 0.85 times the pressure of the system return line.
When designing the pipeline, the pipeline length from the pump to the servo valve should avoid the pump natural frequency as much as possible, that is, an odd multiple of 1.14m. The length of the two branch pipes after the double cylinder pressure filter in the station is preferably 1.14m, so that H-filter can be realized. Vibration reduction.
System instability is the main cause of pipeline shock and vibration. The APC adjustment coefficient and AGC adjustment parameters are adjusted reasonably, so that the system has both good stability and fast responsiveness.
Encrypt the pipe clamps to make the pipe connections secure and reliable.
Remove the two check valves after the pressure filter in the station. The hydraulic fine-tuning work feature is frequently adjusted near the target position, resulting in large flow and pressure fluctuations. When the servo valve is reversed, the flow rate and pressure fluctuation generated by the servo valve propagates along the pipeline to the check valve 3. Due to the isolation of the check valve, the accumulator loses the original damping effect, and the check valve frequently Shutdown not only produces loud noise, but also shortens the service life. After the improvement, a one-way valve is added, so that the flow rate and pressure fluctuation generated by the servo valve are absorbed by the accumulator along the one-way valve 6, which increases the stability of the system.
3,Reduce the tank temperature
The system has a high working pressure, a large flow rate, and a high ambient temperature, so the heat balance temperature is high. Forced cooling must be used to force cooling while minimizing energy losses due to overflow of the relief valve or relief valve.
The medium pressure system has a low pressure (generally 3 to 5 MPa) and the flow rate is small. If the oil source is shared with the high pressure system, a pressure reducing valve is required to cause energy loss, so the medium pressure system is preferably provided with a separate oil supply system.
The tubular direct-acting safety valve is easy to overflow and uses a pilot-operated relief valve.
Water-cooled air conditioners are installed in the station to reduce the ambient temperature.
Maintenance of heat exchangers is a problem that is easily overlooked. Due to the high oil temperature before heat exchange, the quality of the cooling water is the key to ensuring the cooling efficiency. In general, the medium plate factory uses ordinary net circulating water, and the water has a high degree of gravity. It is easy to scale at a temperature of 40 to 50 ° C for a long time, so that the cooling efficiency is greatly reduced. Therefore, the heat exchanger is cleaned at least once a year to ensure cooling efficiency. It is best to set a plate or tube-and-tube cooler with a high heat dissipation coefficient, and select a cooler with a suitable heat-dissipation area according to the heat balance condition to ensure that the oil temperature does not exceed 55 °C.
Use a constant-pressure variable-pressure pump with excellent performance to reduce the energy loss caused by pump leakage.