What should be done about the motor failure of the high-speed centrifuge

The drive part of the high-speed centrifuge and ultra-high-speed centrifuge are high-speed motors, and for high-speed motors, maintenance in the general method of repairing ordinary motors may not be repaired, and after repairing, it may not be able to be used
for a long time.
Before maintenance, it should be judged that the following conditions are undergoing deep treatment
.
First, determine whether the armature needs to be disassembled Observe whether there is a spark between the carbon brush and the commutator when the motor is running, and the degree of spark, (1) there is no spark, indicating that the carbon brush and the commutator are normal and do not need to be repaired; (2) There are only 2~4 very small sparks.
At this time, if the surface of the commutator is flat, most cases do not need to be repaired; (3) In addition to more than 4 very small sparks, there are 1~3 large sparks, then there is no need to disassemble the armature, just use sandpaper to grind carbon brush commutator; (4) If there are more than 4 large sparks, you need to grind the commutator with sandpaper, and even carefully add the commutator at this time, the carbon brush and armature must be disassembled, of course, once the commutator is processed, the carbon brush must be replaced to grind the carbon brush
.
Second, the method of disassembling the high-speed motor Because when disassembling the end cover and armature, the vibration will damage the carbon brush, so the carbon brush should be removed
from the carbon brush first.
And because the angle between the two carbon brushes and the commutator may not be the same, in order to ensure that the original can be restored during installation, the left and right carbon brushes will not be installed backwards, and the left and right carbon brushes must be marked before taking out the carbon brushes, and remember not to touch the contact surface
between the carbon and the commutator.
One end of the high-speed motor, generally has a cooling fan, at the other end may have a speed measurement magnet or velocimetry ring, in the disassembly of the cooling fan blade and magnet or velocimetry ring must be careful, can not the fan blades, speed measuring magnet damage
.
Secondly, a mark should be made between the fan bushing or the magnet bushing and the shaft, so that it can be installed according to the original marked position after the repair is completed, because the dynamic balance test of the high-speed motor is made with fan blades or tachometer rings (tachometer magnets), so when assembling, it must be assembled according to the mark at the time of disassembly, which is an insignificant trivial matter
in general motor repair.
Once the velocimeter ring or fan blade is damaged or not assembled according to the mark, even if the other parts are well repaired.
After assembly, it may also cause unbalanced vibration
of the whole machine when running at high speed.
Do not use hammers, punches when disassembling high-speed motors.
.
.
Wait for hard knocking and hard prying, use a pulling horse
.
When using a pulling horse, pay attention to the tip of the pulling horse directly against
the top eye.
A protective pad is applied to the top of the puller and the top eye pad, the purpose of which is to protect the tip eye on the armature shaft from damage
.
Secure the end caps at both ends of the armature, and mark the end caps before disassembling them so that they can be repaired and put back
as they are.
The bearings on the dismounted armature should be cleaned carefully, clean with clean gasoline, and then fill the bearing chamber with 7014 (or 7018) bearing grease after the gasoline dries (the bearings of high-speed motors cannot use ordinary butter and molybdenum disulfide).

Set aside in a clean place; If the surface of the commutator is flat and has a purple luster, this is an oxide layer that can protect the surface of the commutator, and the powder on the surface can be
removed with a soft brush.
Third, the repair of the commutator (1) The commutator is basically flat, only with minimal scars or sparks, and is ground by hand with water sandpaper without disassembling
the armature.
The order of grinding is: first according to the outer circle arc of the commutator, process a wooden tool, cut several different thicknesses of water sandpaper into long strips as wide as the commutator, remove the carbon brush (please note that the handle of the removed carbon brush and the carbon brush groove are marked to ensure that the left and right are not changed wrong during installation) Attach the commutator with a wooden tool wrapped in sandpaper, press the direction of rotation of the motor with the other hand, and gently turn the shaft commutator to grind
.
Use the order of sandpaper thickness first thick and then thin When a piece of sandpaper cannot be used, then replace it with another finer sandpaper until the finest water sandpaper
is used.
(2) The surface of the commutator is obviously uneven (can be tackled by hand) or the spark when the motor is running, such as the fourth situation
.
At this time, the armature needs to be disassembled, and the machine tool processing commutator lathe should be a precision lathe, the specific process is: the speed is 1 600r/rain, the pass amount is 0.
03mm, and the turning tool is 0.
1 to 0.
05mm The turning tool needs to use the best * alloy turning tool
.
Fourth, the run-in of the armature Install the armature and the carbon brush in the reverse order of disassembly, gently move the commutator with your hand, and manually run in the carbon brush
.
First power running-in, the running-in process is as follows: first in 5 000RPM no load running-in for 10h, in the running-in process found that a large spark needs to stop running-in.
Double-check that the assembly is appropriate
.
If there is no spark, the second stage can be used at 10 000 RPH, and after 4 hours of running-in, everything can be normal, and the third stage
can be entered.
The third stage is 2 500RPM with load, if it is done with a high-speed centrifuge with load.
You can connect the centrifuge's tachometer indication as the criterion for running-in, but be sure to use the highest speed centrifuge head to do light load If you use an ultra-high-speed centrifuge to do load running-in, you must understand the variable speed ratio, and then set the speed such as 80 000r/rain or more when the ultra-high centrifuge, you can use the highest speed small rotor, which can make the load lighter
。 The variable speed ratio of the ultra-high-speed centrifuge is 4.
2:1, so when the tachometer indicates 10 000r/rain, the actual speed of the motor is about 2 500r/rain In the above entire no-load, loaded running-in process, such as the fourth situation, there are several small sparks or more than two large sparks can not continue, in addition to carefully checking whether the installation is qualified, but also to return to the previous running-in process to re-run-in until qualified
.