Tension Measurement of Individual Web Sections

In slitting, the tension measurement of individual webs has so far mainly found its way into
primary slitters / rewinders. On machines of this size, there is sufficient space for several
individual measuring rollers. In the case of more compact machines (up to two meters working
width), the focus is on using winding and differential shafts to keep the material tension of all
parallel web sections as uniform as possible. With this method, however, the individual
material tensions remain unknown and can vary greatly. FMS offers a novel concept with the
FMS-segFORCETM. A measuring roller with several independent force sensors for tension
measurements in each individual web section.

Quickly detecting the smallest of deviations and eliminating their cause
If we imagine the ideal process, the slitting process would run reliably for weeks and months under the
same conditions and produce consistently high quality. However, the reality looks very different.
Significant deviations in the consistency and properties of the individual parent rolls can lead to issues
from the start. These are, for example, discrepancies in material thickness, elasticity, winding quality,
or different environmental influences on the parent roll. In addition, there are system-specific
influences such as component wear and thermal influences and the resulting irregularities in the
manufacturing process. The causes mentioned and their effects are not always easy to identify and
eliminate. With the new solution, manufacturers and machine builders in the converting industry now
have the option of precisely measuring the web tension of individual cut strips. Especially with very thin
and elastic materials and in compact systems, this task places the highest demands on the technology
used.

Discontinuous material properties and varying process parameters
Even minor fluctuations in material quality and process parameters can harm the winding quality. In
this way, typical defect patterns such as telescoping or dishing rolls due to loose windings or damaged
rolls due to excessively tight windings on individual webs or entire wound-rolls can be avoided. The
condition of the differential shafts is also crucial for a consistently high winding quality. Many
mechanical parameters, such as friction coefficients, optimal function of the friction rings, condition of
the roller bearings, etc., must be ideally matched but cannot be monitored directly. However, common
contaminations from dust, etc., have a negative influence here. Thus, constant quality requirements
will no longer be met after a while. Creeping defect patterns in production are not detected. The
tension measurement of individual material panels helps to identify differences between cut strips in
time. With the FMS-segFORCE measuring roller, such defects can be detected as they occur in real
time. The material tension on each individual panel is measured, and the ongoing process can be
better controlled and optimized. Production waste is reduced, and complaints are avoided. No more
defective batches are delivered to customers.

Measuring roller design
The FMS-segFORCE measuring roller consists of a dead shaft on which the individual movable
segments are arranged. The segments are securely locked in place pneumatically via a central
connection in one of the two side brackets. The segments themselves contain the actual non-rotating
force sensor, a compact measuring amplifier, and the bearing in the roller shell. The segments are
supplied with power, and signals are routed wirelessly via the central shaft. A well-protected, automatic
connection of the electrical contacts simplifies the force sensors’ quick axial positioning for the
respective application. Not a single cable needs to be disconnected or reconnected for such
repositioning. The measuring roller is connected to the machine frame on both sides via functional side
brackets similar to pillow blocks. One of these also contains parts of the electronics. Well protected
from dirt and environmental influences. The 24 VDC power supply and the required compressed air
connection are connected to one of the housings. An RJ45 socket is available for data transfer. The
signals can be picked up and either visualized via a PC or forwarded to the PLC. The number, width,
and axial position of the individual segments can be individually adapted to the machine and the process requirements. Broad coverage of different material and slitting widths can be easily achieved
by correctly assigning segment widths and spacings.

Display and data analysis
FMS offers two different data management solutions. The PROFINET protocol provides a universally
applicable Ethernet interface. It can be used to transmit all measured data in real time to the PLC.
Thus, the machine control can be used for displaying actual values and outputting warnings or fault
states in a fully integrated manner. In addition, a separate FMS software offers convenient operation
and configuration options via a standard PC. The force sensors and the display can be configured via
the FMS software. A well-arranged display informs the operator at any time about the status of the
measuring system.

INFOBOX – Coating plant
With up to 40 measuring points along its measuring roller, the FMS-segFORCE offers the possibility
to subdivide the entire web tension into individual segments and display the material tension of the
individual segments in a so-called tension profile. For example, irregularities in the quality of the raw
material or problems in the manufacturing process can be identified quickly and easily.

• High resolution, with up to 40 measuring points across the entire web width
• Tension profile for optimal process understanding
• Detection of process- or material-related defects and faults
• Easy retrofitting