Common basic faults of concrete mixing plants

1. The cement scale is inaccurate in weighing

    This drawback is manifested in the fact that after adding weights for calibration, the precise value can be displayed, but the number does not return to zero after unloading. After reloading the weights after zeroing, the number changes significantly. However, upon checking, the resistance value of the sensor is within the normal range and there is no problem with the appearance.

    The possible analysis elements may include: the Angle iron used to fix the scale frame during transportation has not been removed; Hairpin at the pressure head and pressure plate. The scale body interacts with the outside world. Three sensor types do not match. Uneven loading when weighing materials.

     The method to deal with the shortcomings of the concrete mixing plant is as follows: If the Angle iron used to fix the scale frame for transportation has not been removed, it should be withdrawn in time. If the pressure head or pressure plate gets stuck, it should be dealt with in time to ensure lubrication and no resistance. If the scale body comes into contact with the outside world, it should be isolated in time. If the three sensor types do not match, a sensor of the same type should be replaced. If the material is unevenly loaded, adjustments should be made.

2. The discharge door of the aggregate bin is difficult to open and close when there is no material

    This drawback is manifested as slow and weak cylinder movement. However, upon inspection of the mechanical parts of the discharge door, there is no friction or jamming, and neither the solenoid valve nor the cylinder has any air leakage.

    The possible analysis factors may include: poor gas flow, such as the filter element of the gas-water separator at the gas source being too dirty, which causes poor gas flow, reducing the gas flow per unit time and thus resulting in slow cylinder movement. The muffler is too dirty. When the cylinder operates, the pressure difference between the rod chamber and the non-rod chamber decreases, causing the cylinder to move slowly.

    The method to deal with the shortcomings of the concrete mixing plant is as follows: If the air passage is not smooth, the filter element should be cleaned or replaced in time. If the muffler is too dirty, it should be cleaned in time.

3. No material is discharged from the discharge port

    This drawback is manifested in the fact that when the contactor is engaged and the motor rotates clockwise, the discharge port of the mother and child screw conveyor does not discharge materials. After a short period of time, the air switch trips. After closing the air switch and starting the motor, the circuit breaker still tripped. It was investigated that there was no coagulation of the powder.

    The possible analysis elements may include: the mother machine is reversed; The air switch is damaged. There may be poor contact in one phase of the motor wiring of the mother machine.

    The method to deal with the shortcomings of the concrete mixing plant is as follows: If the mother machine rotates in reverse, adjust the position of any two wires of the mother machine motor. If the air switch is damaged, it should be replaced. If one phase of the motor wiring of the mother machine has poor contact, it should be inspected and dealt with.

4. The stirring shaft is "stuck"

    This drawback is manifested in the fact that when the stirring host is stirring the mortar, the stirring shaft has difficulty rolling and may even stop rotating.

The possible analysis elements may include: severe overloading, material clamps on the shaft; Human error in operation constitutes secondary feeding. Inaccurate weighing; The gap between the stirring blades or side blades and the inner wall of the tank is relatively large, and foreign objects may enter and get stuck between them. Too low voltage; The stirring parameters were set incorrectly.

    The methods to deal with the shortcomings of concrete mixing plants are as follows: If they are severely overloaded and the materials are clamped around the shaft, the mixing capacity should be adjusted and the accumulated mortar should be collected in time. If human error leads to secondary feeding, the remaining materials should be removed and the operation should be carried out in accordance with the process flow. If the weighing is inaccurate, request the operator to reset the scale. If there are foreign objects stuck between the stirring blades or side blades and the inner wall of the tank, the gap between the blades and the liner should be adjusted to no more than 5mm, and the foreign objects should be removed in time. If the voltage is too low, the line voltage should be checked from the beginning. If there are errors in the parameter Settings, the corresponding ingredient data should be carefully checked and corrected in a timely manner.

5. The discharge door of the main machine cannot be opened

    This drawback is manifested in the fact that when the mixing plant is working actively, the main machine's discharge door cannot be opened, and the discharge indicator light does not light up when the mixing is completed.

    The possible analysis elements may include: foreign objects or accumulated materials between the discharge door and the sealing plate; Insufficient pressure in the airway system, leakage in the cylinder or damage to the oil mist lubricator; The wiring between the solenoid valve and the relay has fallen off, is loosely connected or the relay is damaged. The solenoid valve coil is burned out or the valve core is stuck. The time relay is damaged, resulting in no normal input signal for the PLC.

    The method to deal with the shortcomings of the concrete mixing plant is as follows: If there are foreign objects or accumulated materials between the discharge door and the sealing plate, the foreign objects and accumulated materials should be cleared and the discharge door should be flushed. If the pressure in the gas line system is insufficient, there is leakage in the cylinder or the oil mist lubricator is damaged, it is necessary to check whether the oil mist lubricator, joints, cylinders and other parts are damaged. If the wiring between the solenoid valve and the relay falls off, is loosely connected or the relay is damaged, the relay contact output and wiring should be checked and replaced if necessary. If the coil of the solenoid valve is burned out or the valve core is stuck, the solenoid valve should be replaced. If the time relay is damaged, it should be replaced.

6. The conveyor belt deviates

    This defect is manifested in three situations: First, the conveyor belt deviates to the same side both under empty and loaded conditions, that is, the centerline of the conveyor belt deviates laterally, and the conveyor belt leans towards the side with less material. The second is that the conveyor belt deviates to the left or right and has no fixed direction. The third issue is that the conveyor belt deviates in the middle of the entire conveyor belt conveyor. Uneven foundation, material adhesion to flat idlers, unbalanced control of channel rollers, and unbalanced scheduling of main and forced rollers can cause the conveyor belt to deviate.

    If the conveyor belt deviates to the same side both when empty and loaded, it indicates that the tightness at both ends of the conveyor belt is not the same or the frame is not level. At this point, the frame foundation should be leveled first, the adhering material on the flat idler rollers should be removed, and the tensioning arrangement lead screw or counterweight should be adjusted. If the conveyor belt deviates without a fixed direction, it indicates that the conveyor belt is slack and the tensioning arrangement should be adjusted. If the conveyor belt deviates in the middle of the conveyor, it can be corrected by adjusting the position of the idler group.

    Adjustment method: If the conveyor belt leans to one side, the idler group on that side should be moved sideways in the direction of the conveyor belt's forward movement. Alternatively, the idler group on the other side can be moved backward (or the idler support on the other side can be appropriately raised). The adjustment methods for the return idler group and the bearing idler group are the same. For conveying systems with longer conveyor belts, adjusting the idler group is very useful.

    The adjustment of the redirecting roller is a crucial step in the deviation adjustment of the conveyor belt. The installation position of this roller must be perpendicular to the center line of the conveying direction of the conveyor; otherwise, deviation will definitely occur. If the conveyor belt deviates to its right, the bearing housing on the right side should be moved forward (or the bearing housing on the left side should be moved backward). If the conveyor belt deviates to the left side of the roller, the bearing housing on the left side should be moved forward (or the bearing housing on the right side should be moved backward). If the conveyor belt deviates from the driven roller, the adjustment method is exactly the opposite of that for the driving roller.