Lenze MGXQK DC motors - Manual (Page 17)

17
7.3 Wear check of the collector
¯
Under normal operating conditions, the
collector does not need special
maintenance.
Normally, the collector must only be
machined after several sets of carbon
brushes have been used.
¯ In case of strong ovality or clear burns, the
collector must be ground or dressed, if
necessary. Normally a slight regrinding
using a collector finishing stick, which is
adapted to the shape of the collector
running surface, is sufficient.
Dress the collector when:
-- the collector running surface shows
clear chatter marks
-- the collector shows marks in the carbon
brush running surfaces of more than 0.3
mm depth
-- the collector running surface is oval for
more than 0.015 mm
For even ovality of the running surface,
an ovality of 0.03 mm is acceptable
during operation.
-- the height (difference of the radius)
between two bars next to each other is
more than 2 mm
-- there are strong burns at the bars or bar
edge
¯
The following minimum diameter of the
collector running surfaces must not be
exceeded, otherwise a perfect operation is
not ensured.
Motor type Diameter of the collectdor running surfaces
mm
new minimum
MGXRK 090-22 68.0 66.0
MGXRK 100-22 75.5 74.0
MGXRK 112-22 84.0 82.0
MGXRK 132-22 111.0 108.0
MGXRK 160-32 137.0 134.0
MGXQU 080-22 81.5 79.0
MGXQU 100-22 91.3 90.0
MGXQU 112-22 104.0 102.0
MGXQU 132-32 137.0 134.0
MGXQU 160-22 150.0 147.0
MGXQU 160-32 150.0 147.0
MGXQK 063-32 64.0 62.0
MGXQK 100-22 94.6 92.2
MGXQK 100-32 94.6 92.2
MGXQK 160-22 150.0 147.0
MGXQK 160-32 150.0 147.0
Dressing of the collector
1. Machine the running surface of the
collector using a sharp hard metal cutting
tool and minimum cutting rate
Cutting speed 250 -- 350 m/min
2. If necessary, remove insulation between
the collector bars as shown in figure 5:
-- The insulation between the collector
bars must be milled or sawn out up to
1.00.3 mm
-- Milling width in the centre of the
insulation:
0.1 to 0.2 mm wider than the offset of the
bars, since residuals at the bar edges
would cause sparking and increased
wear of the carbon brushes
-- Break collector bar edges slightly under
605to 905after milling
3. Check the surface roughness of the bar,
since carbon brushes tend to vibrate on
very smooth running surfaces which were
”polished” using diamonds:
-- A surface roughness between 1.6 mm
and 4 mm is permissible
-- When the surface roughness is less:
Roughen the bar surface using fine
abrasive paper or a fine grindstone to
accelerate the formation of patina
4. Use a brush to clean the insulation slots
and blow out using compressed air
K33.0004
copper
insulation
Fig. 5: Milling of the bar insulation at the collector
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