The rice compound selection machine is an agricultural machinery used for cleaning and grading rice, which removes impurities and grades them through multiple processes such as screening, air selection, and specific gravity sorting. The common faults are mostly related to the screen mesh, fan, transmission components, and electrical system. The following are detailed classifications and solutions:
1、 Screening system malfunction
Screen blockage
Phenomenon: Slow material flow, no material passing through the screen or reduced throughput, resulting in decreased selection efficiency.
Reason:
Rice contains excessive impurities such as sediment and grass debris.
Improper selection of mesh size (such as small particles accumulating due to being too fine).
The frequency of the vibration motor is too low or the inclination angle of the screen body is insufficient.
Solution:
After stopping the machine, clean the screen mesh and use a soft bristled brush or compressed air to remove blockages.
Adjust the mesh size of the sieve according to the variety of rice (e.g. 10-12 mesh for japonica rice and 8-10 mesh for indica rice).
Increase the frequency of the vibration motor to 50-60Hz, or adjust the inclination angle of the screen body to 3 ° -5 °.
Damaged screen mesh
Phenomenon: Large particles of impurities are mixed in the undersized material, or there is leakage in the undersized material.
Reason:
The mesh material is not wear-resistant (such as ordinary steel wire being scratched by rice husks).
Long term high load operation leads to metal fatigue.
Insufficient tension of the screen mesh during installation, resulting in loose friction during vibration.
Solution:
Replace the wear-resistant mesh (such as polyurethane mesh or stainless steel woven mesh).
Control the feed rate to avoid a single processing capacity exceeding 20% of the rated value.
Reinstall the screen mesh to ensure even tension (adjust with a specialized tensioning tool).
2、 Wind selection system malfunction
Insufficient air volume
Phenomenon: Light impurities (such as rice husks and deflated grains) cannot be absorbed, and the impurity rate of selected rice exceeds the standard.
Reason:
Fan blades wear or accumulate dust, resulting in a decrease in speed.
Air duct blockage (such as accumulation of grass debris at bends).
The fan belt is loose, resulting in a decrease in transmission efficiency.
Solution:
Clean the fan blades and air ducts, and sand the surface of the blades with sandpaper to remove rust.
Check the tension of the fan belt and adjust it to be able to press 10-15mm.
If the fan speed is lower than the rated value (such as 1450r/min), the motor or pulley needs to be replaced.
Excessive air volume
Phenomenon: Full rice grains are sucked away, causing food loss.
Reason:
The fan damper is too wide open.
The fan selection is too large (such as not matching with the selected machine).
Solution:
Gradually close the air damper, observe the flow of material at the suction port, and find the optimal balance point.
If the fan operates at overload for a long time, it needs to be replaced with a suitable model (such as reducing from 7.5kW to 5.5kW).
3、 Transmission system malfunction
Belt slippage or breakage
Phenomenon: The vibration of the screen body weakens or stops, and the fan speed decreases.
Reason:
The belt ages and becomes hard, losing its elasticity.
The pulley wheel is defective, resulting in uneven wear.
The tensioning wheel fails or the tensioning force is insufficient.
Solution:
Replace the belt with the same specification (such as B-type V-belt) and check the wear of the pulley groove.
Adjust the axial position of the pulley shaft to ensure that the end face error of both wheels is ≤ 0.5mm.
Install or replace the tensioner, adjust the tension to the specified value (if manually pressing the middle of the belt, the sinking amount should be 15-20mm).
bearing overheating
Phenomenon: The temperature of the bearing seat exceeds 70 ℃, accompanied by abnormal noise.
Reason:
Insufficient or deteriorated lubricating grease (such as mixing with water).
The bearing is installed too tightly or has insufficient clearance.
Excessive vibration of the screen body causes additional load on the bearings.
Solution:
Add or replace No. 3 lithium based grease (add every 500 hours of operation).
Adjust the bearing clearance again to ensure that the clearance is between 0.05-0.10mm.
Check the angle of the eccentric block of the vibration motor to avoid excessive vibration (it is recommended that the angle of the eccentric block be between 120 ° and 150 °).
4、 Electrical system malfunction
The motor cannot start
Phenomenon: After pressing the start button, the motor does not respond or only buzzes.
Reason:
Power supply phase loss (such as one phase of three-phase power being disconnected).
Motor winding burnout or contactor contact oxidation.
Wrong connection of control circuit (such as reverse connection of start button and stop button).
Solution:
Use a multimeter to check the power supply voltage and ensure three-phase balance (380V ± 5%).
Check the insulation resistance of the motor (should be ≥ 0.5M Ω). If it is lower than the standard, it needs to be dried or rewound.
Recheck the control circuit diagram and correct wiring errors.
Sensor false alarm
Phenomenon: When the equipment is not fully loaded, the display screen prompts "feed blockage" or "screen damage".
Reason:
The sensitivity of the sensor is too high (such as the photoelectric sensor being interfered by dust).
The installation position of the sensor is offset, resulting in distortion of the detection signal.
Solution:
Adjust the sensitivity of the sensor (such as adjusting the distance of the photoelectric sensor to 5-10mm).
Reposition the sensor to ensure it is vertically aligned with the detection target.
5、 Other common faults
Uneven feeding
Phenomenon: Accumulation or interruption of screening materials, affecting the selection effect.
Reason:
The conveying capacity of the elevator is unstable (such as the jumping teeth of the bucket elevator chain).
Improper adjustment of the opening of the feed gate.
Solution:
Check the tension of the elevator chain and replace the worn hopper.
Install a flow meter to automatically adjust the gate opening based on the rice flow rate (such as PID control).
出料口堵塞
Phenomenon: The selected rice cannot be discharged, resulting in equipment shutdown.
Reason:
Malfunction of the discharge screw conveyor (such as blade jamming).
Unreasonable design of discharge outlet (such as too small bend radius).
Solution:
Disassemble the screw conveyor and clean the tangled straw or stones.
Transform the discharge outlet and increase the radius of the elbow to more than 3 times the pipe diameter.