Why should the DC motor commutator mica chamfer and chamfer?
A surface roughness is not enough, the No. 0 sand paper polishing in the brush under the turning or warm condition, but after the copper powder blowing. Two is because the mechanical processing causes the surface circle and the big axle not to be concentric, but when rotates in high speed produces the vibration. The cause of the misalignment is the use of mandrel tapers that do not correspond with the taper of the exciter bore. In general, the motor shaft taper is 1/10, so the spindle can be 1/10, so the test, to measure the radial runout of commutator (designated as 0.05mm code), radial runout in turning state indicator measurement
If the commutator surface wear severe, but also cause vibration or vibration of the brush, so you need to transfer device surface roughness and radial runout value for regular inspection. First, when the surface roughness degree (refer to the commutator piece because of heart in the axial form of uneven wear) over procedures delineated 0.5 ~ 1.0mm, deal with the commutator turning processing, or because of bad brush and spark, to have the technical ability of the unit can be used in turning (5.4 in detail). Second, because the machining error makes the commutator increase, resulting in the operation of the brush in the commutator surface beating, light will produce sparks, heavy can not provide excitation current, generator can not rise voltage. There are two main reasons.
For chamfering: I think that for small motors, just reverse the corners of the commutator. Large motors should be chamfered to reduce carbon brush wear and reduce spark, especially for positive and reverse motors.
Mica undercuting is a must. Mica than commutator commutator wear than hard, mica, if not under the moment motor used for a period of time, the mica sheet will be raised, motor will have a lot of spark, motor can not normal operation seriously. At this point, carbon brush wear faster.
