Common Fault Diagnosis and Maintenance Skills of Worm Gears

Common Fault Diagnosis and Maintenance Skills of Worm Gears

During the long-term operation of the worm gear mechanism, affected by factors such as working condition load, lubrication conditions, installation accuracy and wear, various faults are likely to occur. If not diagnosed and handled in time, it will lead to reduced transmission efficiency, increased equipment vibration and noise, and even cause serious problems such as equipment shutdown and component damage. This paper sorts out the causes, diagnosis methods and solutions of common faults of worm gears, and provides maintenance skills to help equipment maintenance personnel quickly troubleshoot problems and extend the service life of equipment.

I. Common Faults and Diagnosis and Solutions

Common faults of worm gears mainly include meshing noise, tooth surface wear, tooth surface scuffing, jamming, reduced transmission efficiency, etc. The causes and solutions of various faults are as follows:

1. Meshing noise (harsh or dull noise during operation)

Causes: Excessive or insufficient meshing clearance; tooth surface wear and tooth profile distortion; worm or worm gear installation eccentricity and coaxiality deviation; insufficient lubrication or deteriorated lubricating oil; foreign objects invading the meshing area.

Diagnosis method: After stopping the machine, manually turn the wheel to feel whether the meshing resistance is uniform; observe whether the tooth surface has wear, scratches and foreign objects; detect the installation coaxiality and center distance; check the oil level and oil quality of the lubricating oil.

Solutions: Adjust the meshing clearance to a reasonable range; trim or replace the worn and distorted tooth surface; calibrate the installation accuracy and adjust the center distance and coaxiality; supplement lubricating oil or replace the lubricating oil that meets the requirements; clean the foreign objects in the meshing area, check the sealing condition of the protective cover, and prevent foreign objects from invading again.

2. Tooth surface wear (wear, scratches, pitting on the tooth surface, and even thinning of the tooth thickness)

Causes: Insufficient lubricating oil, deteriorated oil quality and lubrication failure; unreasonable meshing clearance and increased friction; improper material matching and insufficient wear resistance; excessive working condition load exceeding the design bearing capacity; foreign objects invading and increasing wear.

Diagnosis method: Observe the appearance of the tooth surface and check the change of tooth thickness; detect the pollution degree and wear particles of the lubricating oil; judge whether there is overload combined with the working condition load.

Solutions: Replace high-quality lubricating oil to ensure sufficient lubrication; adjust the meshing clearance; replace the severely worn worm or worm gear and select reasonable material matching; control the working condition load to avoid overload; strengthen the sealing of the protective cover to prevent foreign objects from invading. For worm gears with slight wear, laser cladding repair technology can be used to restore the tooth surface size and hardness and reduce the replacement cost.

3. Tooth surface scuffing (adhesion, melting and tearing on the tooth surface, and even tooth surface failure in severe cases)

Causes: Low transmission efficiency, a lot of heat generated by friction and high oil temperature; improper selection of lubricating oil, mismatched viscosity and failure to form an effective oil film; insufficient meshing clearance and severe tooth surface friction; excessive working condition load and frequent impact load.

Diagnosis method: Observe whether there are adhesion and melting marks on the tooth surface; detect the oil temperature to judge whether it exceeds 80℃; check the viscosity and oil quality of the lubricating oil.

Solutions: Optimize heat dissipation measures, add cooling devices to reduce oil temperature; replace lubricating oil with matching viscosity and select gear oil containing extreme pressure additives; adjust the meshing clearance to reduce tooth surface friction; control the working condition load to avoid impact load. When the tooth surface scuffing is serious, the worm and worm gear need to be replaced.

4. Jamming (the equipment cannot operate normally, and manual wheel turning is difficult)

Causes: Lubrication failure, severe tooth surface scuffing and wear; foreign objects invading leading to meshing jamming; excessive installation deviation, excessive coaxiality and perpendicularity; overload leading to gear tooth bending fracture or plastic deformation; bearing damage leading to worm or worm gear jamming.

Diagnosis method: After power failure, manually turn the wheel to judge the jamming position; use an endoscope to check the tooth surface state and foreign object situation; detect the installation accuracy and bearing state; analyze the load data to judge whether there is overload.

Solutions: Clean foreign objects after stopping the machine; replace damaged bearings, worms or worm gears; calibrate the installation accuracy and adjust the coaxiality and perpendicularity; optimize the lubrication system to ensure sufficient lubrication; install a load monitoring device to avoid overload. When the jamming is serious, a hydraulic jacking device is used to assist disassembly to avoid secondary damage caused by violent disassembly.

5. Reduced transmission efficiency (reduced output speed and torque, increased energy consumption)

Causes: Tooth surface wear and excessive meshing clearance leading to increased friction loss; lubrication failure and oil film damage; worm or worm gear installation eccentricity and poor meshing; bearing wear and increased friction resistance; excessive working condition load exceeding the design efficiency range.

Diagnosis method: Detect the input and output speed and torque, and calculate the transmission efficiency; observe the tooth surface wear; check the lubricating oil state and bearing operation; detect the installation accuracy.

Solutions: Trim or replace the worn tooth surface and bearings; replace high-quality lubricating oil and supplement lubrication; calibrate the installation accuracy and adjust the meshing clearance; control the working condition load to avoid overload.

II. Daily Maintenance Skills

Daily maintenance is the key to preventing worm gear faults and extending service life. It is necessary to follow the principle of "regular inspection, timely maintenance and prevention first", focusing on the following points:

1. Lubrication maintenance: Regularly check the oil level and oil quality of the lubricating oil. Generally, replace the lubricating oil every 3-6 months, and shorten the replacement cycle under harsh working conditions; select lubricating oil with appropriate viscosity and type according to the working environment and working conditions, select low-temperature grease for low-temperature environment, and select extreme pressure gear oil for high-temperature and high-load working conditions; regularly clean the oil tank to remove impurities and wear particles in the oil to ensure the cleanliness of the lubricating oil.

2. Regular inspection: Check the meshing area once a week to clean foreign objects and burrs; check the installation accuracy once a month to calibrate the coaxiality, center distance and meshing clearance; check the bearing state once every 3 months to see if there are abnormal noise, heating, oil leakage and other conditions; check the tooth surface wear once every 6 months, and detect the tooth thickness and tooth profile accuracy with professional tools.

3. Environmental protection: Ensure that the equipment operation environment is clean, avoid dust, water vapor and corrosive gas intrusion; the protective cover must be well sealed to prevent foreign objects from entering the meshing area; equipment in rainy areas should be equipped with IP65 protection level shell and built-in dehumidification device; heat preservation measures should be taken in the cold environment in northern China, and low-temperature adaptive lubricating oil should be selected.

4. Load control: Avoid long-term overload operation of the equipment, reasonably arrange the working time, and avoid continuous long-term operation leading to high oil temperature; for impact load working conditions, install hydraulic buffers to absorb instantaneous impact energy and protect the worm gear and bearings.

5. Preventive maintenance: Establish an equipment maintenance account to record maintenance time, maintenance content, fault conditions and handling measures; use vibration analysis, spectrum detection and other technologies to find potential faults in advance (such as worm gear eccentricity, bearing wear) and intervene in advance; regularly train operators to standardize the operation process and avoid equipment faults caused by improper operation.

III. Maintenance Notes

1. During maintenance, the power must be cut off and the machine stopped to ensure that the equipment is in a static state to avoid safety accidents;

2. When adjusting the meshing clearance, professional tools must be used for detection to ensure that the clearance is uniform and reasonable, avoiding being too large or too small;

3. When replacing the worm or worm gear, it is necessary to ensure that the parameters of the new part are consistent with the original part. After installation, carry out trial operation to check the meshing condition and operation state;

4. When replacing the lubricating oil, the old oil must be completely cleaned to avoid mixing old and new oil, which affects the lubrication effect;

5. For equipment that has been idle for a long time, it is necessary to manually turn the wheel regularly and supplement lubricating oil to prevent the tooth surface and bearings from rusting and jamming.

Through scientific fault diagnosis and standardized daily maintenance, the failure rate of the worm gear mechanism can be effectively reduced, the service life of the equipment can be extended, and the stable and efficient operation of the transmission system can be ensured to provide guarantee for production work.