Control system for aluminum
web anodizing line with database server interface.
SUMMARY:
The anodizing line uses a programmable logic controller (PLC)
and a human machine interface workstation (HMI) for process
control. A Microsoft SQL Server database was used for production
setup and process information storage.
DESCRIPTION:
The line has an unwind stand, several washing and rinsing
tanks, an anodizing tank, intermediate and main pull roll stands
and a center driven rewind. Control enclosures for each line
contain the line drives (AC vector drives), the PLC and the
HMI workstation. The PLC controls various temperature, flow,
level, pH and conductivity loops in the wash and rinse tanks.
The PLC controls the amperage of the anodizing probes. The
PLC monitors unwind roll diameter and varies pneumatic brake
pressure to maintain a constant unwind tension independent
of roll diameter. The PLC controls speed references to the
intermediate and main pull roll drives to create tension draw
control. The PLC sends a torque setpoint with a taper bias
to the rewind roll drive operating in torque control mode.
This allows the rewind to create tight rolls with less tension
as roll diameter increases, eliminating roll telescoping.
An HMI workstation allows an operator to select the product to
run. The product information is queried from a central database
server and used to automatically setup the PLC for the production
run. Once selected, the operator starts the run and the PLC/HMI
inserts real-time process information back to tables in the database
server. Linked tables from a local database in the production
office provide the production scheduler with the means of inserting
production information into the database server. Automatic report
generation is accomplished by querying information from the process
information stored in the database. |
