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How are bearings inspected for operation

How are bearings inspected for operation


After the bearing is installed, a running check is carried out to check whether the installation is correct.Small machines can be rotated by hand to ensure smooth rotation.Inspection items due to foreign bodies, scars, indentation caused by the operation of the unstable moment due to poor installation, poor processing of the installation seat due to torque instability due to too small clearance, installation error, sealing friction caused by excessive torque, etc.If there is no abnormality, power operation can be started.

Large machinery cannot be rotated manually, so the power should be cut off immediately after no-load starting, and the machinery should be idled to check whether there is vibration, noise and contact of rotating parts, etc. After confirming that there is no abnormality, the machine should enter into power operation.

Power operation, starting from no load and low speed, gradually increases to the rated operation under the specified conditions.During the test run, check for abnormal sound, changes in bearing temperature, leakage or discoloration of lubricant, etc.If abnormal conditions are found, stop the operation immediately, check the machinery, and remove the bearings if necessary.

Bearing temperature can generally be inferred from the external temperature of the bearing housing.But using oil hole to directly measure the temperature of bearing outer ring is more accurate.Bearing temperature, from the start of operation gradually increase, usually 1 to 2 hours after the temperature stable.If the bearing is not installed properly, the temperature will rise sharply and abnormal high temperature will occur.The causes include too much lubricant, too little bearing clearance, poor installation, too much friction of sealing device, etc.In the case of high speed rotation, the wrong bearing structure and lubrication mode are also the reasons.

Check the rotating sound of the bearing with stethoscope, there is strong metal noise, abnormal sound, such as abnormal sound.The causes include poor lubrication, poor precision of shaft or bearing seat, bearing damage, foreign body invasion, etc.

Common bearing failures are as follows:

1. Tile surface corrosion: Abnormal concentration of nonferrous metal elements was found by spectral analysis;There are many submicron wear particles in iron spectrum.Lubricating oil moisture exceeds the standard, acid value exceeds the standard.

2. Journal surface strain: There are iron cutting abrasive particles or black oxide particles in the iron spectrum, and the metal surface has backflame color.

3. Surface corrosion of journal: Abnormal iron concentration was found by spectral analysis, submicron particles with many iron components were found in the iron spectrum, and excessive moisture or acid value of lubricating oil was found.

4. Surface strain: Cutting abrasive particles were found in the iron spectrum. The abrasive particles were composed of nonferrous metals.

5, tile back fretting wear: spectral analysis found that the iron concentration is abnormal, there are many iron components in the iron spectrum submicron wear particles, oil moisture and acid value is abnormal.

Under the condition of liquid lubrication, the sliding surface can be separated by lubricating oil without direct contact, and the friction loss and surface wear can be greatly reduced

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