Nexen RSD200 964531 - Manual (Page 18)

FORM NO. L-21161-E-0108 1
A typical unwind application begins with a new full roll.
To insure that the dancer arm stabilizes as quickly as
possible, the SPLICE signal should be used to reset
ADAPTATION to NEW ROLL ADAPTATION before the
machine starts. This shortens the time it takes for the
RSD200 to adapt its gains to the new roll.
If a SPLICE signal is not used, the dancer arm may be
sluggish on the first start with a full roll, because the
adaptation process will begin at MINIMUM ADAPTATION
and take longer to reach the optimum gain. Once the
RSD200 adapts to the new roll, ADAPTATION will
level off and subsequent starts will adapt faster and
the arm will quickly move into position. During a run,
the adaptation process continually adjusts the gains to
account for changes in the roll.
When the START signal goes high at the Start/Stopped
input, the RSD200 will begin adapting. The web must
begin to move at this instant.
As the roll begins to accelerate, the Dancer Arm will seek
its home position as determined by SETPOINT% (0%
is minimum storage position, 100% is maximum storage
position). The roll will continue to decrease in size along
with the ADAPTATION and OUTPUT values. During
constant speeds the dancer arm will remain stable, but
the output values will not be steady.
During a machine stop, ADAPTATION and OUTPUT
values will initially increase to overcome a roll’s inertia.
After a STOPPED signal is given, the ADAPTATION value
will behave as follows:
• If the ADAPTATION value was greater than NEW
ROLL ADAPTATION before the stop, then ADAPTA-
TION goes to the NEW ROLL ADAPTATION value.
• If the ADAPTATION value was in between NEW
ROLL ADAPTATION and MINIMUM ADAPTATION be-
fore the stop, then ADAPTATION will remain between
these two values. This is useful for small rolls that are
started and stopped very frequently. The ADAPTA-
TION value will be very close to the actual value needed
and the Dancer Arm will be stable.
• If the ADAPTATION value was less than MINIMUM
ADAPTATION before the stop, then ADAPTATION
goes to the MINIMUM ADAPTATION value.
When the RSD200 is in STOPPED mode, the
ADAPTATION value will remain constant and the
OUTPUT value will change depending on the Dancer
Arm’s position. The STOPPED OUTPUT value found in
the OUTPUT LIMITS pane of the SETUP window is used
to limit how high the output can rise. This is useful for
applications where a minimal amount of tension on the
web is desired during a stop.
After the START signal is given, the RSD200 adaptation
will begin from the level as defined previously. This
process is necessary to provide an adaptation value that
is approximate for larger rolls and one that is much closer
for smaller rolls.
R
eSetting
a
DaPtatiOn
Any time the SPLICE signal is given, the ADAPTATION
value will be reset to NEW ROLL ADAPTATION. Also, if
the ADAPTATION value rises too high (likely after a web
break) it can be reset to MINIMUM ADAPTATION by
moving the Dancer Arm to its maximum storage position
while the RSD200 is stopped.
.2 UNWIND APPLICATION
Small Roll Large Roll
Acceleration Acceleration
Run Speed Run Speed
Deceleration Deceleration
Stopped
Start/Stopped Signal
Splice
Signal
New Roll Adaptation
Min. Adaptation
Optimum Gain
Reached
Adaptation
Figure 1