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Replacement technique of laboratory centrifuge rotor

Time : 2022-01-24 Hits : 17

If the centrifuge is not used properly in the laboratory, the rotor will not be taken out and the experiment process will be delayed. Generally, the rotor can not be taken out from the centrifugal cavity, which is mainly caused by the adhesion between the spring chuck and the centrifuge motor spindle. According to years of experience in using centrifuges, during centrifugation, condensate water or carelessly spilled liquid may permeate between the spindle and the central hole of the rotor. After centrifugation, if the spring collet is not pulled out quickly and is used continuously for a long time, corrosion and adhesion will occur between the spindle and the spring chuck, resulting in the operator being unable to take out the spring Chuck. This phenomenon is more likely to occur in high-speed refrigerated centrifuge. Here are some ways to solve this problem.

1. Simplified method
First, screw out the original locking screw and screw it into the thread hole of the main shaft with a screw of the same thread specification. Pay attention not to screw in the end completely. With the cooperation of two people, one person holds the rotor with both hands and raises it slightly upward. Pay attention not to use too much force to avoid deformation of the motor support frame. The other person uses a hammer to knock down the screw on the upper part of the motor spindle through a thin rod. After repeated several times, the rotor can be separated from the main shaft.

2. Special tool method
If the method mentioned above fails to take out the rotor, it indicates that the bonding condition is serious. The rust remover can be dropped into the joint of the main shaft and the rotor for rust removal and infiltration. After waiting for a day or so, use a special puller to take out the rotor. In the same way, first, select the appropriate size of the puller according to the size of the rotor, and then buckle the puller's hand to the bottom of the rotor. The head of the screw rod of the puller is against the screw in the thread hole of the main shaft. After the position of the puller is righted, the screw rod is rotated clockwise with a wrench. According to the principle of screw mechanism, the puller's hand will produce a huge pulling force, and then the rotor will be removed from the main shaft be divorced from.

3. Key points
(1) In any case, the replacement screw must be screwed into the thread hole of the spindle in order to protect the spindle thread and the original locking screw.
Otherwise, in case of damage to the original thread, it may be made into motor scrap.
(2) Force to understand the appropriate, not brute force smash. When the resistance is too high, the time of rust removal and invasion can be prolonged.
(3) After the rotor is taken out, the outer surface layer of the main shaft and the surface layer of the inner hole of the rotor shall be polished with fine sandpaper to remove the rust and apply grease to prevent the bonding again.

4. Preventive measures
(1) To enhance the daily maintenance, the joint surface of the rotor and the main shaft should be wiped clean and coated with grease.
(2) Especially for high-speed refrigerated centrifuges, do not close the cover door immediately after use, but let the moisture, condensate and corrosive gas in the centrifugal chamber evaporate completely and return to normal temperature before closing the cover door.
(3) After each centrifugation, take out the rotor as soon as possible. If a rotor is not replaced or taken out for many days, it is very easy to cause adhesion. In the most serious case, the whole machine will be scrapped.
(4) Each time the screw is tightened, do not use too much force. Otherwise, it will cause the screw sliding thread trip, and in serious cases, the motor will be scrapped. When the motor rotates counter clockwise, the inertia screw itself will produce a clockwise tightening force, which can just make the rotor be tightened. Therefore, when tightening the rotor, it is only necessary to feel a slight effort on the wrist.

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