Troubleshooting methods for the vibration of the leveling cylinder of the asphalt paver screed

When an ABG423 asphalt paver is in operation, the left screed leveling cylinder shows the following jumping phenomenon (at this time, the left screed leveling cylinder is under the control of the leveling instrument, solenoid valve and bidirectional hydraulic lock) : Initially, the displacement of the cylinder jumping up is 6-10mm, and then it drops rapidly. The displacement of the drop is slightly smaller than that of the rise. This phenomenon occurs intermittently, but the operation of the right ironing plate leveling cylinder and other hydraulic circuits is normal. Since the structure of the ironing plate adjustment systems on the left and right sides of this machine is exactly the same, and their actions are corrected and adjusted by the pulse signals of their respective levelers, we adopt the "swap method" for troubleshooting. The specific approach is as follows:

(1) Shut down the machine and cut off the power. Swap the leveling instruments on the left and right sides (controlling the left and right solenoid valves and the bidirectional hydraulic lock assembly respectively). The machine was restarted and the paving operation was carried out. It was found that the fault was still on the left side.

(2) When the left and right solenoid valves and the bidirectional hydraulic lock assembly were swapped, the fault still occurred on the left side.

(3) The pressure of the left and right screed plate leveling cylinders 1 and 2 was measured when they were overflowing. The measured pressure was 21 mpa and remained good, indicating that the pressure on both sides of the leveling cylinders was normal and there was no internal leakage in the leveling cylinders.

(4) The two oil pipes of the flow distribution valve 5 (marked with 2L/min) were swapped and installed, but the fault still occurred on the left side.

(5) When the manual electrical adjustment switches controlling the left and right side solenoid valves and the bidirectional hydraulic lock assembly on the operation console were swapped, the fault still occurred on the left side. At this point, it is determined that the cause of the malfunction does not lie in the hydraulic and electrical systems. So, we focused our attention on the left ironing plate to adjust the upper arm 5.

Observation reveals that when the fault phenomenon occurs, the left ironing plate adjustment arm is in close contact with the isolation plate 4. After a careful search, it was found that the installation screw 6 of the isolation plate was loose. The tail end of the screw had exceeded the plane of the isolation plate and interfered with the adjustment arm of the left ironing plate. Post-event analysis shows that the cause of this malfunction is: Under the control of the left leveling instrument, solenoid valve and bidirectional hydraulic lock assembly, when the left ironing plate leveling cylinder drives the left ironing plate regulating arm to move upward from bottom to top and closely adheres to the isolation plate, the tail end of the isolation plate installation screw 6 interferes with the edge on the surface of the regulating arm, thereby preventing the arm from moving upward. This leads to an increase in the upward traction force of the left ironing plate leveling cylinder (the pressure of the hydraulic system rises), but due to the relatively small contact surface where interference occurs, when the upward traction force of the leveling cylinder increases to a certain extent, the left ironing plate adjusting large arm will overcome the resistance and slide outward, but the position of the large arm has not yet reached the position controlled by the leveling instrument. At this point, the pressure in this hydraulic circuit is higher than that during normal operation, while the left solenoid valve and the bidirectional hydraulic lock assembly are still in the open state. This causes the left screed leveling cylinder to be adjusted upward excessively (with a displacement of 6-10mm). Under the control of the left leveling instrument, solenoid valve and the bidirectional hydraulic lock assembly, The left ironing plate leveling cylinder will be adjusted downward again (with a displacement of 4-7mm) to bring the ironing plate to its normal position. This phenomenon will recur as the underlying road surface changes. After tightening the installation screws of the isolation plate, the fault phenomenon disappeared and the paver returned to its normal working state.