A. speed control failure
It can be said that the failure of production speed control of color coated sheet is caused by crawling, slow speed, unstable speed and non adjustable speed. (1) Crawling. When the pressure cylinder is low, the phenomenon of continuous motion is called creeping. The phenomenon of color coated plate production is caused by many factors, such as: air is mixed in the system, the compressibility of air makes the hydraulic oil compressible, resulting in the reduction of the stiffness of the oil, causing the creeping phenomenon of the actuator such as the oil cylinder. In addition, crawling phenomenon can also be caused by other reasons, such as: the pressure is too low; the pressure and flow in the system have too large fluctuations; the leakage caused by the heavy wear of the actuator; circuit abnormalities and other reasons will make the movement of the actuator uneven, and eventually lead to the crawling phenomenon of the system speed.
(2)。 1) It's slow. Wear of hydraulic pump, directional valve and other actuators, too low regulating pressure of overflow valve, insufficient opening of shut-off valve or speed regulating valve, and too large load of the system will cause the speed of the system to decrease. 2) The speed cannot be adjusted. Flow control valve stuck; manual speed control valve damage are naturally caused by the speed can not be adjusted. In addition, if the electric signal of the electro-hydraulic proportional speed control valve can not be adjusted, the speed of the system can not be adjusted. 3) The speed is not stable. The change of the environment temperature causes the change of the leakage, which leads to the change of the oil flow and the instability of the speed of the actuator.
B. failure of action control
The out of control action of color coated plate production is mainly manifested in that the hydraulic actuator does not complete the start and end action according to the preset procedure or the process requirements of the unit, and even unexpected action or unstable action may occur.
(1) The actuator cannot start the action. The main reason for this phenomenon is that the directional valve of the hydraulic system can not be opened normally. The specific reasons are as follows: the spool of the directional valve is stuck or its top rod is bent; the electromagnet of the directional valve is burnt out or the wire is loose; the control relay is out of order; the shut-off valve and speed regulating valve in series in the circuit are stuck; the hydraulic power is not transferred from the unloading state to the working state; If the load part is abnormal and cannot be pushed, the action cannot be started normally.
(2) The actuator cannot end the action. The main reason for this phenomenon is that the directional valve of the hydraulic system can not be closed normally. The specific reasons are as follows: the directional valve is stuck or the spring is broken, resulting in the valve core can not be reset; the failure of the executive switch and relay causes the electrical signal of the directional valve not to disappear in time, which will make the action unable to start normally.
(3) Unexpected action. The unexpected action is mainly caused by the failure of directional valve and electrical signal. For example, the opening and closing position of the two position directional valve is reversed; the internal wear of the directional valve is serious. The fault of electric signal causes the electromagnet to get the wrong electric signal, which leads to misoperation