Fault diagnosis and troubleshooting of pipe jacking machine

1. The correction system has no action
A Φ 1 800 mm mud water pressurized pipe jacking machine (expandable to 2000mm), with a total length of 4705 mm for the rotary excavator system, a cutter head torque of 354 kN · m, a cutter head speed of 2.3 r/min, and a driving power of 30 × 3 kW. The stroke of the correction hydraulic cylinder is 85 mm, and the thrust of the correction hydraulic cylinder is 980 kN multiplied by the total mass of the main engine (t). When the top pipe is 200 meters high, the correction system fails and cannot produce correction actions, resulting in the inability to proceed with construction.
The correction system of the rotary excavation system of the pipe jacking machine adopts an electro-hydraulic integrated operating system, consisting of a hydraulic oil tank, oil filter, oil inlet filter screen, electric motor, hydraulic pump, one-way valve, overflow valve, pressure gauge, electromagnetic reversing valve, hydraulic lock, overload overflow valve, mud water tank electromagnetic reversing valve, mud water tank door overflow valve, correction hydraulic cylinder and other components.
The hydraulic pump transfers hydraulic oil to the control valve and delivers it to the correction hydraulic cylinder according to the required correction situation. However, due to the working pressure of the correction hydraulic cylinder not reaching the required 20 MPa (only 16 MPa), the system pressure is low, and the correction hydraulic cylinder cannot perform normal correction operations.
There are several reasons for the low pressure in the correction hydraulic system, including the failure of the relief valve; The electromagnetic directional valve is severely worn, resulting in internal leakage; Correct hydraulic cylinder leakage; The oil inlet filter is clogged; The power of the hydraulic pump has decreased.
According to the analysis results, adjusting the pressure of the overflow valve has no significant effect; Using the transposition method to replace overflow valves of the same model in other parts for debugging did not show any effect, indicating that the overflow valve is in good condition. Checked the electromagnetic directional valve and found no oil leakage, loose valve core, or unclear gear position, indicating that the electromagnetic directional valve is also in good condition. The pressure test was conducted on the correction hydraulic cylinder, and the pressure was normal without any internal leakage. Remove the oil inlet filter screen for inspection and no blockage was found. Finally, it is determined that the decrease in hydraulic pump power is the main cause of the malfunction.
Stop the correction hydraulic system, cut off the power, remove the hydraulic pump from the oil tank, replace it with a hydraulic pump of the same model, and test run the machine. The system pressure can reach 26 MPa, and the correction operation is working normally.
2. The correction system cannot correct to the left
After inspecting the electrical operation, hydraulic system, and soil discharge system of a Φ 2000mm soil pressure balance pipe jacking machine, it was found during the comprehensive adjustment and testing process that the correction system of the rotary excavation system did not move to the left, while other directions were normal.
Firstly, the electromagnetic directional valves on the left and right sides were swapped using the transposition method, but the left side still could not be corrected. Further repositioning and adjusting the hydraulic cylinders on the left and right sides, the left side still cannot be corrected. Through the above transposition debugging, it is demonstrated that the hydraulic circuit of the correction system is in good condition. When continuing to investigate, the front swing part and rear follow-up part of the rotary excavation system were disassembled and separated. It was found that the waterproof rubber ring of the pipeline at the connection between the front and rear steel shells was aging and deformed, affecting the left movement of the correction system.
The aged and deformed waterproof gasket at the connection between the front and rear steel shells was replaced, and the correction system operated normally to the left after the test run.
3. Hydraulic pump station directional valve malfunction
In the construction of sewage pipelines,