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Winding calculator
Winding and unwinding endless material
Drive application: Winding calculator
Winding calculators are used when endless material is
unwound for further processing or rewound after processing.
This may be necessary e.g. in the paper, plastics, textile
or sheet metal industries. It is very important that the
speed of the material transport remains constant. The speed
of the material roll is changed in inverse proportion to its
radius. To prevent the material from tearing, it is wound
smoothly and the tension must be kept constant. The
following description of the drive solution is based on two
unwinders.
- Endless, e.g. in a paper machine. The roll is unwound
without interruption at a constant circumferential
velocity. The radius is calculated by the IPOSplus®
program in MOVIDRIVE®. The speeds n1 and n2
and the diameter d0 of the pull-off roller are known.
- Clocked, for example in a trimmer. The unwinder has to
start and stop cyclically. Clocked further processing
requires special precautions to ensure jerk-free
material transport. One precautionary measure is to
guide the material over a jockey roll, which acts as a
buffer to compensate for the tensile force fluctuations
and load shocks of clocked operation.
The solution with MOVIDRIVE®
Connection via system bus
The MOVIDRIVE® solution assumes that each
unwinder and pull-off roller is driven by its own motor.
Both MOVIDRIVE® inverters are connected with the
standard system bus (SBus). External encoders on the line
can be avoided through the data exchange between the
inverters. The inverter can recognize possible band tearing.
An automatic threader ensures that the process continues as
soon as possible.
Guide with jockey roll
In the case of clocked further processing, the guide around
the jockey roll is extended. The jockey roll acts as a
buffer to compensate for the tensile force fluctuations and
load shocks arising from clocked operation. The position of
the jockey roll is entered with a potentiometer and the
signal is forwarded to the MOVIDRIVE® of the
winder.
IPOSplus®
A significant feature of the MOVIDRIVE® drive
inverter, the IPOSplus® positioning and sequence
control system, now comes into play. It turns the MOVIDRIVE®
into a real winding calculator. An IPOSplus®
program in MOVIDRIVE® calculates the setpoint of
the torque or the setpoint of the unwinder speed based on
the speed of the unwinder and pull-off rollers and the
specified valid tensile force (for example, via the fieldbus
of a PLC).
The advantages at a glance
- The MOVIDRIVE® units exchange the data for
torque control or speed control via the system bus.
- The roll radius is calculated independently in
MOVIDRIVE®. No additional measuring
equipment is required.
- In the application without jockey roll, integrated
torque control, also for standard AC motors with
encoder.
- In the application with jockey roll, integrated PI
controller for speed control for the unwinder.
- All movement control is carried out by the IPOSplus®
program in MOVIDRIVE®.
- Safe operation of asynchronous AC motors even in the
field weakening range.
- Band tearing is recognized and threading help is
started automatically.
- Simple integration into higher-level machine control
systems is possible via fieldbus.
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