How to deal with the failure of motor assembly line during installation and debugging?

The core of fault handling in motor assembly line installation and debugging is to follow the logic of "first locating the cause → then solving it pertinently → finally verifying the effect", so as to avoid the fault expansion caused by blind operation, and focus on troubleshooting from three dimensions: mechanical, electrical and technological.

I. Core process of fault handling

Shutdown and safety guarantee

Press the emergency stop button of the assembly line immediately to cut off the power supply and air supply (if pneumatic equipment is used) in the fault area, so as to avoid personal injury and parts damage caused by no-load operation of the equipment or misoperation of parts; Set warning signs in the fault area, and prohibit irrelevant personnel from operating.

Fault phenomenon recording and preliminary judgment

Record the fault performance in detail, including: working procedures when the fault occurs (such as bearing press-fitting and rotor assembly), abnormal phenomena (such as abnormal sound, jamming and error code), involved equipment parts (such as conveyor belt, mechanical arm and sensor), and preliminarily judge the fault types (mechanical jamming, electrical disconnection, program error, etc.).

Check the reasons by dimension

Check in the order of "mechanical → electrical → process" to avoid omission; When troubleshooting, give priority to the parts that are prone to problems (such as connecting bolts, terminal blocks and sensor probes), use tools (such as wrenches, multimeters and oscilloscopes) to assist detection, and record the troubleshooting results.

Targeted solution and testing

Repair the faults according to the troubleshooting results (such as fastening loose parts, replacing damaged parts, and recalibrating procedures); After the repair, carry out no-load test (run for 10-15 minutes) to see if there is any abnormality, and then carry out belt test (try to assemble with 1-2 motor parts) to verify the assembly accuracy and running stability.

Second, the common fault types and treatment methods

1. Mechanical failures (accounting for about 40%, such as jamming, abnormal noise and substandard assembly accuracy)

Conveyor belt/guide rail stuck

Reasons for investigation: there are foreign objects (such as screws and metal chips) in the guide rail, insufficient tension of the conveyor belt and insufficient lubrication of the guide rail.

Treatment method: clean the foreign body in the guide rail and purge the gap with compressed air; Adjust the tension wheel of the conveyor belt (the tension is subject to no obvious sag of the conveyor belt); Apply special lubricating oil (such as lithium-based grease) on the contact surface of the guide rail to avoid oil pollution of parts caused by excessive use.

Accuracy deviation of press-fitting equipment (such as bearing press-fitting machine)

Reasons for investigation: positioning deviation between pressure head and fixture, calibration failure of pressure sensor, and inaccurate displacement caused by wear of lead screw.

Treatment method: re-calibrate the concentricity between the pressure head and the tooling (the deviation should be ≤ 0.02 mm); Calibrate the pressure sensor with a standard weight (ensure that the pressure error is ≤ 2%); Check the wear of the lead screw. If the wear exceeds 0.1mm, replace the lead screw and re-adjust the displacement parameters.

2. Electrical failures (accounting for about 50%, such as equipment unresponsiveness, sensor error, motor non-operation)

No response/error code of the device (such as "E01 power failure")

Troubleshooting causes: the power switch is not closed, the terminal is loose or oxidized, and the controller (PLC) program is wrong.

Treatment method: check the state of power switch in the distribution box to ensure the three-phase voltage is stable (380 V 5%); Fasten the loose terminal with a screwdriver, and polish the oxidized terminal surface with sandpaper; If it is a program error, import the correct backup program, and test after restarting the controller.

Sensors (such as position sensors and photoelectric sensors) have no signal.

Reasons for investigation: the sensor probe is blocked (such as dust and residual parts), the distance between the sensor and the target is deviated, and the sensor circuit is open.

Treatment method: wipe the sensor probe with alcohol to remove the obstruction; Adjust the installation position of the sensor to ensure that the detection distance meets the requirements of the manual (for example, the photoelectric sensor is 5-10 mm away from the target part); Use multimeter to detect the on-off of sensor circuit, and replace the broken cable or damaged sensor.

3. Process failures (accounting for about 10%, such as parts can't be located and parts are damaged after assembly)

Incorrect positioning of parts (e.g. the rotor can't fit into the casing)

Reasons for investigation: wear of fixture locating pin, out-of-tolerance of parts' own dimensions, and feeding deviation of feeding mechanism.

Treatment method: measure the diameter of the locating pin, and replace it if the wear exceeds 0.03mm; Sampling parts size (such as casing inner diameter and rotor outer diameter), eliminating out-of-tolerance parts; Adjust the position of the push cylinder of the feeding mechanism to ensure that the parts are sent to the tooling center (deviation ≤0.05mm).

Parts are damaged after assembly (such as bearing fracturing and coil scratching)

Reasons for investigation: excessive press-fitting pressure, burr on the edge of tooling, and wrong assembly sequence.

Treatment method: reduce the press-fitting pressure to the process standard value (refer to the motor assembly manual, such as the bearing press-fitting pressure is usually 5-10kN); Use a file to polish the burr on the edge of the tool to ensure the smooth surface; Check the assembly sequence (such as "first install the stator → then install the rotor") and correct the wrong process flow.

Iii. Matters needing attention after troubleshooting

Recording and archiving

Record the failure reason, treatment method, replacement part model and test result in the Equipment Failure Handling Account, so as to facilitate follow-up tracing and prevent similar failures.

Verification before batch production

After troubleshooting, 10-20 motor parts shall be assembled continuously, and the assembly qualification rate (98% or higher) and equipment operation parameters (such as speed and pressure) shall be checked to ensure that there are no potential problems.

Preventive maintenance

Optimize the maintenance plan according to the fault type, such as frequent mechanical faults, and increase the frequency of cleaning and lubricating the guide rail; If there are many electrical faults, check the terminal and backup program regularly to reduce the failure probability in subsequent debugging or production.