In the machining process, sometimes the hydraulic station is newly installed and commissioned, and it is put into operation soon. The working pressure suddenly becomes zero or decreases to a small value during operation, and multiple adjustments are useless. At the end of the inspection, iron scraps were found on the spool of the relief valve, small as mung beans, and large as a fingernail. This type of phenomenon usually occurs several times in succession on the same hydraulic station.
Before the hydraulic station is assembled and commissioned by the manufacturer, all parts must be carefully cleaned and all kinds of holes and pipes should be washed and dried with compressed air of 0.69MPa; before installation and commissioning on the mine site, it should be cleaned.
When processing the blind holes of each valve and valve block, sometimes the drill bit is machined to the bottom of the deep blind hole, and a small amount of drill cuttings are also spirally adhered to the bottom of the blind hole, and the drill bit is removed from the hole without forming the chip discharge hole. . The spiral iron filings stuck to the bottom of the blind hole will not easily break outside the discharge hole during cleaning and short-time test. This situation is generally difficult to detect.
Only when the hydraulic station establishes a high working pressure (about 5.9 MPa), the high-pressure oil repeatedly passes through the holes of each pipe, and the alternating accumulation acts on the adhered iron filings, and the spiral debris is finally high-pressure oil due to fatigue. The liquid breaks and breaks into a number of small pieces, which follow the hydraulic oil flowing into the valve and are retained on the valve core.
The newly installed hydraulic station at the mine site should switch the hydraulic station more frequently between the working pressure and the closing pressure before commissioning, and the action of the switch should be slow. On the one hand, the performance of the hydraulic-brake system can be considered, as well as stability and reliability. On the other hand, if the above-mentioned stuck iron filings are present, the automatic rupture can be broken and retained on the valve spool. When the oil pressure is greatly reduced, the adjustment is out of control. Disassemble the valve to remove broken iron filings. Generally, the hydraulic station can be removed by continuously switching for about 4 hours.
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