Checking The Accuracy Of The Joint - Balluff BML-M0 I A Série Notice D'utilisation

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BML-M0 -I -A
Magnetic Tape – Incremental Magnetically Coded Position Measuring System
4
Installation (continued)
7. Cut tape M2 so that the resulting distance D between
both tapes is 11 mm (width of 1 pole pair + 1 mm for
fine positioning). The gap between the two tape ends
indicates where to cut (Fig. 4-11).
8. Place the aid tape on tape M1 and move it into a stable
position (Fig. 4-12).
Move shortened tape M2 towards the joint until the
marking (a) on the tape is flush with the marking (b)
or (c) on the machine part (Fig. 4-12). The aid tape
must now be "engaged" in a stable position. If needed,
slide tape M2 to the right or left by 1 mm to find the
position with the greatest attraction.
⇒ The distance between the tapes should be
approx. 1 mm.
9. Test: If the aid tape has two stable positions, one on
M1 and one on M2, tape M2 must be repositioned or
shortened again (see step 7).
10. As soon as the tape is in the final position, remove the
protective film and bond the tape.
11. Make sure to protect the tape at the joint using a cover
strip or potting material.
4.7.2

Checking the accuracy of the joint

A higher deviation in linearity may occur in the joint area
rather than on the tape. This is due to the gap in the joint.
The smaller the gap (e.g. a few tenths of a mm), the lower
the non-linearity.
If not precisely aligned, the number of increments output
by the BML is increased near the joint, as if the speed has
increased.
– If the BML is moving at a slow speed, it can correct
this temporary deviation back to null.
– If the BML speed is very high (e.g. maximum speed), a
lasting non-linearity may be set. For example, the BML
may lose a pole in the position if the non-linearity is ½ a
pole.
Check as follows to see if this problem occurs in your
application:
1. Move the BML to the start position and mark the
position (e.g. 100000 µ).
2. Slowly move the BML forwards over the joint and then
move the system back to the start position at
maximum speed.
3. If the BML shows the same start position (i.e.
100000 µ) at the marking, there is no lasting non-
linearity.
14 english
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M1
S N S N S N S
D
Fig. 4-11: Cut at 11 mm
N S N
N S N S N S
S
~1 mm
Fig. 4-12: Position shortened tape
M2
a
S N S N S N S
c a
b
11 mm
S N S N S
a
S N S N S
a
c
b