Balluff BML-M0 Série Notice D'utilisation page 42

BML-M0 _ -... / BML T _ _ -...
Magnetic Tape – Magnetic Encoder System
4
Installation (continued)
7. Cut tape M2 so that the resulting distance D between
both tapes is 11 or 21 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).
M1
S N S N S N S
Fig. 4-11: Cut at 11 mm
8. Place the aid tape on tape M1 and move it into a stable
position and attach using adhesive tape (Fig. 4-12).
9. 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 have only one stable position into which it
engages. If needed, slide tape M2 to the right or left to
find the position with the greatest attraction.
⇒ The distance between the tapes should be
approx. 1 mm.
S
N
S S N
S N N
~1 mm
Fig. 4-12: Position shortened tape
10. 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).
11. As soon as the tape is in the final position, remove the
protective film and bond the tape.
12. Make sure to protect the tape at the joint using a cover
strip or potting material.
16 english
M2
a
S S
S N S N N
a
c b
D 11 mm
N S N S N S
a
S S N S N S
c
b
4.9.2 Checking the accuracy of the joint
A higher non-linearity may occur in the joint area rather
than on the tape. This is attributable to the gap at the joint
and any possible jump from the pole period of M1 to the
pole period of M2. The smaller this gap (e.g. a few tenths
of a millimeter) and the more even the pole distribution
when changing from M1 to M2, the less the non-linearity.
In the area of the joint, if the distance in the X direction is
not enough, the number of increments per millimeter the
BML outputs will be greater, as if the speed were higher
(and vice-versa if the distance is too great). Excessive
speeds can result in a temporary deviation.
– 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.
In actual applications check for increased non-
linearity as follows:
1. Move the BML to the start position and mark the
position (e.g. 100000 µm).
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.
a
100000 µm) at the marking, there is no lasting non-
linearity.
If there is a lasting non-linearity of one pole width, tape
M2 must be repositioned.