Analysis of common faults in batching system of concrete mixing plant

There are occasional failures in the daily production of the concrete mixing plant, especially in the batching system, such as inaccurate batching, non participation of the silo in batching, non unloading of the silo, etc. the following small series will share with you the common failure analysis of the batching system of the concrete mixing plant. Come and have a look.

Common fault analysis of batching system of concrete mixing plant:

1、 The accuracy of ingredients is out of tolerance.

In the batching process, the weighing value displayed by the batching control instrument is accurate, but the weighing value of batching is inconsistent with the set value, and the batching accuracy exceeds the allowable range. There are many reasons for such failures, including: the set values of fast and slow batching are inappropriate; Large fluctuation of feed flow leads to large change of overshoot; The dry and humidity of materials change greatly; The set value of tolerance range is too large; The time setting of out of tolerance check delay is too short; The set value of instrument parameter automatic compensation and out of tolerance inspection is unreasonable; The time parameter values of digital filtering and batching are unreasonable.

The following measures shall be taken for the above fault causes: the initial overshoot shall be close to the actual value as much as possible; Properly reduce the batching flow; Ensure the balance of dry and humidity of materials; Set the allowable deviation value to not exceed the batching accuracy range; Set the delay time of out of tolerance inspection to be greater than 2.5s, and set the automatic compensation of instrument parameters and out of tolerance inspection to "1"; Set appropriate parameter values during batching.

2、 The silo does not participate in batching.

During the batching process, a silo does not participate in batching, the relevant batching indicator lights on the instrument and operation panel are on, but the motor or solenoid valve does not act. The possible causes of this fault are: insufficient air pressure of the material scale; Relevant dosing actuator (motor or solenoid valve) is damaged; Loose and virtual connection between AC contactor and motor; The intermediate relay and contactor of relevant circuit are damaged and the relevant wiring is abnormal.

At this time, check the air compressor and air circuit connector, use a multimeter to check the motor, solenoid valve and relevant lines, and replace the intermediate relay or AC contactor in time. When this fault occurs, if the relevant batching indicator light is not on and the instrument display does not move, it may be that the batching control instrument is damaged or the power supply is abnormal.

3、 The silo does not discharge.

It shows that a silo does not unload under automatic working conditions, and the silo unloading indicator light and scale unloading indicator light on the operation panel do not light up. The possible causes of this fault are: the discharge door of the mixer has been fully closed, but the closing signal has not been fed back to the controller; The limit switch is damaged or displaced; Batching is not started in a silo. At this time, check the limit control feedback circuit, adjust or replace the limit switch, timely start the "batching tool" for feeding, and complete the production of the current batch in a semi-automatic manner.

If the unloading indicator light of the silo on the operation panel is on when this fault occurs, the reason may be insufficient air pressure or serious leakage in the unloading cylinder. Check the air circuit and replace the worn parts in time; If the solenoid valve does not have 220 V AC power supply, the intermediate relay coil may be burned and the solenoid valve power supply line wiring may be poor. Check the wiring in time and replace the relay; If the solenoid valve is powered by 220 V AC, the solenoid valve coil may be burned, the valve core may be stuck, and the valve body seal may be damaged. The solenoid valve shall be replaced in time.

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