The arm eliminates
the need for the conventional
carriage of a tube-bending machine.
It also promotes manufacturing precision
by retaining the part for the entire
process.
The machine, called Uni-vercell,
was developed by Unison. A Powerlink
system controls four motion axes,
plus the I/O needed for continuous
operation. This involves tube bending
and end forming, and general operational
control of the cell. A NextMove
e100 controller from Baldor Electric
Co. manages four MicroFlex e100
servomotor drives which control the
tube-bending head’s clamp, pressure
die, and bend-arm axes, plus actuation
of the end-forming tool for flaring
and compressing. In addition to these
core functions, the controller manages
all of the cell I/Os, plus the link to the
front-end user interface.
Unison estimates the daisy-chained
nature of the high speed Powerlink
network reduced the size of the electrical
system and the wiring and system
building tasks by about 50% compared
to conventional analog motion
control.
The 100-Mbits/sec network provides
enough bandwidth to dynamically
control each motor’s position
and torque parameters. This helps
make the bending process precise.
Some I/Os sit directly on the controller
while the rest sit on distributed
servodrives, yet still get controlled in
software as if they were local. Remote
I/Os are CANopen I/O modules.
There is no front-end user interface.
It is on a laptop that connects as
needed to the cell’s NextMove e100
controller for downloading production
programs. But the cell can connect
to a local man-machine interface
through a standard Powerlink gateway
to a PC or Ethernet.
The Uni-vercell can fabricate parts
to an overall accuracy of 0.1 mm. Although
the cell is optimized for high
volumes, Unison says its robotic arm
can handle batch production as well.
With typical energy consumption of
around 1.5 kW (measured using an
example part with three bends and one
end form, including stacking at the
end of the process and 100% inspection),
electricity costs about 7 Euros
per day.
Software control of the bending lets
operators adjust torque and movement
profiles to improve bend quality. Complicated
shapes that might be difficult
to make on conventional hydraulic
machines are no problem because the
machine can make intervening adjustments
or moves between stages to avoid
collisions.
Operators program bends and end
forms by inputting data such as position,
angle, rotation, and torque. Simply
positioning the arm manually and
capturing the data program the robot’s
intervening movements.
Make Contact
Watch a video of the cell: tinyurl.com/yvw9n7
Baldor Electric Co., baldor.com
Unison, unisonltd.com