Customer Question: The label industry is very sensitive
to curl and we are finding that controlling web tension on narrow web
printing presses is very important. I work with customers using our flexible
packaging and labels and am interested in learning how your web tension
systems work and how we might be able to use a data acquisition system
to collect web tension data over time.
Answer: DFE manufactures components for monitoring
and controlling tension in any type of application. For a useful primer
on web tension control and PID controllers see the article Tension
Basically, DFE tension controllers come in three different output versions
to correspond to the tensioning mechanism being used by the customer.
The controllers can produce a pneumatic output (P version) for clutches
and brakes, a low voltage 0-10V output (D version) typically for motor
drives, or high voltage (V version) 0-24, 0-45, or 0-90VDC outputs for
eddy current or magnetic particle clutches or brakes.
For those applications requiring an interface to motor drives, our controllers
can be used in a follower mode, where the control output follows the machine's
speed. Our newer controllers can also compensate for roll diameter changes
when used on an unwind or rewind — e.g. the WebHandler™3
controller. Line follower mode with diameter compensation is especially
useful on machines with high accelerations.
All DFE electronics, whether they are closed-loop controllers or just
indicators, produce a 0-10V signal which represents measured tension over
the calibrated range (for example 10V=250lbs of tension). This tension
signal can be brought into a data acquisition card for logging over a
period of time. We can supply an off-the-shelf generic data acquisition
card for this purpose, or recommend a brand-name card to you, and assist
with setup for acquiring useful tension data.
If desired, a second channel of the data acquisition card can be used
to bring machine speed in. Software normally used with these cards can
be configured to show actual line speed and tension. This provides the
capability to observe whether tension upsets occur when the machine's
speed changes, for example.
Some DFE tension controllers and electronics devices have RS232 and/or
RS485 output capability. This allows a laptop computer to receive the
data from the controllers and display it, using the serial port already
present on most laptops. This can be the least expensive way to get tension
information into a computer for analysis. DFE has an experienced software
engineer on staff and we are pleased to be able to offer simple yet powerful
Windows® based software for accessing and operating our digital WebHandler™3 Controllers remotely
via laptop or PC. The software is included with the purchase of either
of these controllers.
If you have specific questions about how any of our components work,
please email firstname.lastname@example.org or email@example.com
or call one of our Application Engineers at (603) 332-6150 to discuss
your application. We can recommend which components are appropriate to
meet your performance or data analysis needs.