Constant Tension Central Winder


In many industrial sectors, such as the paper,
plastics, textile or sheet metal industries, materials in continuous,
flexible strip form (web) must be unwound or rewound before and
after processing. To prevent the material from tearing, winding
must be absolutely jerk-free and the tension must be kept constant.

Constant Tension Central Winder
This constant tension center winder has an
unwinder with two drives: one for the take-up roller and one for
the pull-off roller. Usually, the pull-off roller operates with
speed control, in which case the material is unwound at a constant
web speed. The winder determines the tensile force, while the speed
signal from the pull-off roller functions as a control signal. In
many applications, a drive is not required for the pull-off roller.
It can be replaced by a master encoder that delivers the master
signal for the winder.

SEW offers the “Center Winder” application module
as the comfortable solution for your drive task. This application
module is a component of the MOVITOOLS® software
for the application version of MOVIDRIVE® B.
The user-friendly interface guides you through the process of setting
the parameters. Only those parameters required for the specific
application, such as fixed diameter and tension, must be entered.
The application module uses this information to create the control
program and loads it into the inverter. MOVIDRIVE® then takes over the entire motion

This saves a substantial amount of time in
the startup process, and as everyone knows: Time is money.
The functions of the “Center Winder” application
module are divided into four areas:

  • Calculation of the roller diameter
  • Calculation of the tensile force
  • Adjustable winding curve
  • Either terminal or fieldbus control

The tensile force must be adjusted very accurately
for flawless operation of the winding machine. To achieve this,
the following parameters must be taken into account:

  • Current winding diameter
  • Winding characteristics
  • Friction coefficients of the mechanical components

Many winding machines measure winding diameter
to determine and set the correct winding speed. In this case, the
diameter does not need to be measured. The diameter is calculated
by the IPOSplus® program in MOVIDRIVE®.
No matter how large the variety of applications
for constant tension center winders, the wide range of functions
provided by the application module offers the right solution for every

  • Choice of fieldbus or terminal
  • Web speed and current diameter displayed
  • Counter for material length
  • Monitoring material tearing

During operation, all of the important data
is displayed on the center winder monitor.
With many materials, it is necessary to reduce
the tensile stress as the winding diameter increases. This can be
regulated using the center winder application module. You can set
the winding characteristics to your requirements using a user-friendly
editor. This is done either in a freely defined fashion with a table
or using a hyperbolic function.
  • User-friendly user interface.
  • Only the parameters needed for the application must
    be entered.
  • Guided parameter setting process instead of complicated
  • The winding diameter is calculated independently in
    MOVIDRIVE®. No additional measuring
    equipment is required.
  • All movement control is carried out by the IPOSplus® program in MOVIDRIVE®.
  • Material tearing is recognized automatically and the
    threading help started.
  • Simple integration into higher-level control systems
    via fieldbus.

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