After the vacuum pump is used for a long time, there will be some abnormal phenomena, such as the vacuum drop, oil leakage at the seal, stagnation of the vacuum pump rotation, even "stuck", serious oil pollution, rust in the vacuum pump cavity, big impact sound of the rotating blade, hard objects falling into the vacuum pump cavity, causing the vacuum pump overheating and other abnormal phenomena. At this time, the vacuum pump must be repaired and disassembled.

The steps are as follows,

1. Cut off the power supply and remove the vacuum pump from the vacuum system,

2. Use gravity method or pressure method to discharge and collect dirty oil to avoid environmental pollution;

3. Remove the belt and pulley key (the double-stage rotary vane vacuum pump includes the belt);

4. First remove the low vacuum end, remove the rear end cover, and then take out the low vacuum rotor, rotor and spring;

5. Remove the front cover and take out the high vacuum rotor, rotor and spring;

6. Remove the mirror, exhaust valve, exhaust cover, etc;

7. Clean the removed metal parts thoroughly with gasoline and dehydrate them with alcohol. Rubber parts can be dissolved in 15% sodium hydrofluoride and boiled to remove oil. For parts with burr or rust, it can be gently ground with oilstone or metallographic sandpaper to remove rust spots and burrs. The cleaned parts must be dried;

8. During assembly, first install the second stage, hold up the spring and rotating blade into the rotor, then put it into the vacuum pump chamber, install the front end cover, and then install the positioning pin. Tighten the screws evenly and symmetrically. After assembly, the rotation should be flexible and even. After installing the front stage rotor and rear end cover, install the exhaust valve (the exhaust valve piece should be close to the valve seat) and other parts, such as air ballast device.

In addition, the precautions for vacuum pump maintenance are as follows:

1. Check whether the oil level is low and the dry oil mark is regular. If the low dry oil mark, should be timely refueling, apricot. Will affect the vacuum degree of the vacuum pump. The amount of fuel should not be too much, otherwise it will cause difficulties in starting and fuel injection.

2. Should always pay attention to whether the vacuum pump operates normally, whether there is any special sound, whether the machine is overloaded, and whether the temperature of the motor vacuum pump is too high.

3. Water cooling vacuum pump, should prevent cooling water interruption, vacuum pump temperature should not exceed 70 degrees. If the ambient temperature is lower than 5 degrees, the cooling water in the vacuum pump should be drained after shutdown to prevent the vacuum pump body from freezing and cracking.

4. The vacuum pump should be kept clean by belt, and no other objects should be placed on the vacuum pump.

5. Pay attention to the belt tightness is appropriate. Adjust or replace if necessary.

6. The vacuum pump oil should be replaced 1-3 times a year. The mechanical vacuum pump used in vacuum melting may change oil frequently every month. This is due to the dry vacuum pump in the use process, vacuum pump oil will be ash, moisture or other dirt pollution or soap, carbonization, affect the performance of the vacuum pump, therefore, the need for regular oil change according to the specific situation.