Constant tension center 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.

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 “Central Winder” application module as the comfortable solution for your drive task. This application module
is a component of the MOVIDRIVE® application software MOVITOOLS® MotionStudio. 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 control.

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 task.

  • Choice of fieldbus or terminal control

  • 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 programming.

  • 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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