Nexen MB25B 911996 - Manual (Page 5)

FORM NO. L-20127-L-0513 5
MB TENSION SENSOR LOCATION
Figure 3 illustrates correct MB Tension Sensor location for
winding or unwinding control. One transport roll A located
between the MB Tension Sensors and roll stand serves to
fix the web angle over the Sensor Roll.
Figure 4 illustrates angular changes as the roll changes
diameter during processing, if roll A is not used. These
angular changes will cause incorrect readings from the
MB Tension Sensors and must be avoided by use of roll
A (See Figure 3).
Figure 5 illustrates a common mistake in MB Tension
Sensor mounting. In this configuration, the S Wrap Drive
will effectively isolate tension into two zones, T
1
and T
2
(A nip roll at the same position would provide the same
isolation). The roll stand brake or clutch can only control
tension in the T
1
zone. Since the MB Tension Sensors are
mounted in the T
2
zone, they cannot sense any tension
changes caused by the roll stand and can not be used
for closed loop control. The MB Tension Sensors must
be moved to position A for proper control of the roll stand
and T
1
tension.
MB TENSION SENSOR MOUNTING
Mounting dimensions for the four frame sizes are given in
MOUNTING DIMENSIONS, (See Figures 13-17).
MB Tension Sensors MB05, MB11, and MB25 may be
mounted at any angle (See Figure 6). MB33 and MB41
should be mounted to a rigid horizontal or near horizontal
surface.
All MB Tension Sensors must be mounted according to
the following guidelines:
• Flatness must be 0.002” [0.05 mm] over the length
of the MB Tension Sensor. This can be achieved by
milling of the mounting surface.
NOTE
Any shimming required for Sensor Roll leveling must
be done between the MB Tension Sensor and pillow
block. Never shim between the MB Tension Sensor
and MB Tension Sensor mounting surface.
INSTALLATION
FIGURE 3
A
Sensor
Roll
Sensors
FIGURE 4
Sensor
Roll
Sensors
FIGURE 5
A S Wrap
Drive Sensors
T T 1 2
FIGURE 6
MB MB
MB
MB
MB MB
MB
MB
(continued...)