Leanin' Tree
Conveyor System
Overview
The Leanin' Tree greeting card company
of Boulder has gone forward with a plant
expansion for their customized seasonal
line of cards. It is 12,500 square feet on
grade level with a mezzanine.
C H Systems, a Denver conveyor system
provider, selected Arapahoe Controls to
engineer and provide the controls package.
Hardware
Considerations taken into account were
cost, support, reliability, and ease of
use. Automation Direct's DL06 PLC was
selected along with physical buttons and
indicator lights on the face of the control
panel. Motor controls are Cutler Hammer mag
starters with their solid state overload
relays. An STI safety relay was used for
the emergency stop control.
The local display option was included and
messages were programmed in to pinpoint
maintenance issues.
Operation
The operator simply starts either the upper
level system or the lower level by pressing
the paired stop/start PB on the door of the
panel. Warning lights/buzzers alert
personnel in the area that conveyors are
about to start. Everything else is
automatic! Conveyors are stopped/restarted
as required by boxes being detected at
merge points, and walk-thru gates being
opened.
Programming
Automation Direct has a very useful feature
called stage programming. It was deployed
in this program to segregate the control
area's and functionality. Using these
features can cut programming time
considerably and further save system
costs.
Another feature called on was the shift
register. Using these, along with a pair of
photoeyes at each merge point virtually
eliminates the possibility of cases
colliding in the system. Startup testing
has verified this promise.
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