Created on:2021-07-21 10:21

Principle and fault of hydraulic system for side guide plate of coiler

Principle and fault of hydraulic system for side guide plate of coiler

The side guide device of the coiler in the main rolling line of a hot strip mill is used to prevent the deviation of the strip, align the strip with the rolling line, and lead it into the underground coiler. The side guide plate is driven by hydraulic cylinder, and the guide plates on both sides of the side guide plate are controlled by two sets of independent and identical hydraulic servo systems. The synchronization of the guide plates on both sides is realized by PLC software,

(1) Principle of hydraulic system for side guide plate of coiler

Taking the hydraulic system of one side of the side guide plate as an example, the principle of the hydraulic system of the side guide plate of the coiler is shown in Figure K.

K1.jpg

The operator can set the opening degree of the side guide plate through the operator terminal. PLC takes the deviation value between the operator's setting value and the actual position detected by the displacement sensor in the hydraulic cylinder as the input signal to control the opening degree of the servo valve and the direction of the hydraulic oil flow, so as to make the actual position of the side guide plate hydraulic cylinder reach the operator's setting value, which constitutes the electro-hydraulic position control servo system.

The two pressure transmitters of the rod cavity and the rodless cavity of the servo cylinder are used to detect the pressure on both sides of the rod cavity and the rodless cavity of the hydraulic cylinder, and participate in the control of the electro-hydraulic position control servo system. The role of the rodless cavity side of the servo cylinder is to prevent the equipment damage caused by the excessive load of the side guide plate in the normal work, and play the role of safety valve.

(2) Side guide plate hydraulic system fault phenomenon

After the hydraulic system of the side guide plate has been continuously flushed for a period of time (as shown in Fig. L), the flushing accuracy of the system has reached nas5 level after testing. Before the installation of the servo valve, the bypass circuit is debugged as planned, mainly to check whether the mechanical part of the side guide plate interferes with other equipment, and adjust the opening degree of the one-way throttle valve of the bypass circuit to adjust the telescopic speed of the servo cylinder The pressure of the safety valve on the side of the rodless chamber, the pressure of the pressure transmitter and the zero point of the displacement sensor of the servo cylinder, etc.

The hydraulic system consists of the main circuit and the bypass circuit. The bypass circuit is used when the main circuit fails or the side guide plate is repaired. The main circuit is put into use during the normal rolling process of the side guide plate. The main circuit and the bypass circuit are separated by three hydraulic control check valves before and after the servo valve. The servo cylinder is equipped with ilvdt displacement sensor to detect the actual position of the hydraulic cylinder. The hydraulic components are provided by American company.

When the operator selects the "side guide bypass" mode, the side guide bypass circuit is put into use, the electromagnetic directional valve DTI controlled by PLC is de energized, and the three hydraulic control check valves in front and behind the servo valve are closed. At this time, the operator operates the "side guide open" or "side guide close" button to power on DT2 or DT3 of the side guide bypass circuit through PLC, The hydraulic cylinder of the side guide plate is controlled to retract or extend, and the unilateral guide plate of the side guide plate is opened outward or closed inward, and can stay at any position.

When the operator selects the operation handle as "side guide servo" mode, the main circuit is put into use, the electromagnetic directional valve dt1 controlled by PLC is powered on, the three hydraulic control one-way valves before and after the servo valve are opened, and the main circuit is put into use.

During the debugging, it is found that: when the DT2 or DT3 of the electro-hydraulic directional valve 10 is powered on and the flushing valve 16 is in the cross position, there is continuous oil flow sound at the flushing valve 16, so it is very difficult to manually switch the flushing valve of the servo valve; When DT2 or DT3 loses power, it is easy to manually switch the flushing valve of servo valve. When the DT3 power on servo cylinder is extended, the oil flow sound in the flushing valve is larger and the temperature rise is faster. When the servo cylinder is in place, the oil flow sound in the flushing valve increases and the temperature rise is faster; When the DT2 power on servo cylinder retracts, the oil flow sound is small, the temperature rise is slow, and there is no oil flow sound after the servo cylinder retracts.

Home    Article    Principle and fault of hydraulic system for side guide plate of coiler