Structural application of commutator

Update:08 Sep 2020

The commutator is a component of the DC permanent magnet series motor in order to keep the motor rotating. Structurally, the commutator is a circle with several contact pieces connected to each contact on the rotor. The two electrodes connected outside are called brushes to contact it, and only two of them are contacted at the same time. The principle of the commutator is that when the coil passes the current, it will be rotated by the attraction and repulsion force under the action of the magnet. When it turns to balance with the magnet, the originally energized wire will be compared with the contact on the corresponding commutator. The sheet is separated from the brush, and the brush is connected to the contact sheet corresponding to the set of coils that produces the driving force, so that the DC motor will start to rotate after repeating it.

Polishing knowledge of commutator

After long-term operation of the DC motor, due to poor commutation, unreasonable brush arrangement and improper brush material, streaks, regular burns, pitting on the surface, and uneven wear on the surface of the commutator tend to form axial For waviness, a special grinding stone is generally required to polish the commutator. During use, the grinding stone needs to be glued to the bottom of the grinding tool with the handle. The speed of the commutator should be about 10m/s during grinding. Use both hands to stably press the sand on the commutator. The hand-held pressure should not be too high, and it should be polished until no surface burn marks and grooves are visible. After the grindstone is polished, use a fine-grain emery cloth around the wood block, and use the same method to polish it again. For highly demanding commutators, canvas is also used instead of fine emery cloth, and then polished again. Note: Do not use emery cloth to polish the commutator, because emery particles embedded in the surface of the commutator can scratch the surface of the commutator and the brush, causing the surface to form fine grooves and affecting the formation of oxide film. When the surface of the commutator is severely burned, the channel is deep and the wave degree exceeds 0.5mm, the grinding of the commutator will not be able to improve the surface condition of the commutator, and the surface of the commutator should be turned.

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