Edited by Leland Teschler
Stretch a carpet an extra inch, save
$100,000. That was what a manufacturer
of ready-to-mount automotive
carpeting was trying to
accomplish with a linear-motion
system used in its manufacturing
process.
Operations begin with workers
manually laying a top layer of
carpeting over a mold having a
pad set into it. The linear system,
containing bearings and a carpettack-
filled pneumatic actuator,
then can grab and
then stretch the carpet.
The motion system must
be strong enough to work
continuously.
Initially, profiled
slider rails in the system
would wear out in only
about three months. It
took about two weeks
to change them, during
which production came
to a halt.
Contamination and
a high cantilever turned
out to be the two main
reasons for failure. Carpet fibers
were finding their way into the recirculating
ball tracks and plugging
them up. The facility was
spending an average of $104,000
every year in replacement costs.
A Compact Rail linear-bearing
system from Rollon Corp., Sparta,
N.J., solved the problem. It has
raceways on the inside of the rails
as protection from damage and
contaminants. This feature also
lets the rail and slider mount into small, compact, areas. Built-in,
spring-loaded wipers in the heads
and the lateral seals on the sides
of the slider ensure operation in
superdirty environments. These
‘Lubed for Life’ wipers continually
deposit a thin film of oil on the
races. Individual sliders can carry
up to 3,300 lb and can move up to
9 m/sec.
Compact Rail also absorbs
rotational positioning errors,
misalignments between lateral
planes, longitudinal parallelism
errors, or a combination of all of these while still maintaining the
system’s original preload setting.
It is designed to provide smooth
movement whether mounting
plane parallelism can be guaranteed
or not. After more than three
years, the Compact Rail systems
are still running on the manufacturer’s
50 molds with no need for
replacement.
An artist’s
depiction of a
carpet stretching
mechanism
shows the linear
rails on which
the moving
station travels.
In real life, the Rollon
linear-rail installation
looks like this. The inset
details the raceways on