Aluminum Rolling Mill
The Reflective Memory real-time network was used to enhance a PLC-controlled Aluminum Rolling Mill operation. Distributed PLCs were used to monitor and control a 3,500 ft/min rolling mill. The PLC control loop had a resolution response that allowed 2 to 3 feet of aluminum to pass through before actuators could respond. These actuators were responding to apply/release pressure on the aluminum to vary the thickness.
Using Reflective Memory, a system of communication between separate VME-based systems was developed to reduce this response time. The 2 to 3-foot resolution was reduced to 4 inches, resulting in tremendous waste reduction and quality improvement in the final product. Data relating to the mill was imported to the PLC which immediately wrote it into Reflective Memory’s memory, thereby sending it to a separate VME computer system to transfer complex control algorithms.
The system sends the output control data back to the PLC by simple write commands to its Reflective Memory. In this application, data appears in local Reflective Memory in an almost instantaneous fashion on the PLC. The data transfers are fast and the computations are so fast that the PLC runs its control loop with no delays. Thus, the PLC operates at its maximum scan rate because it is only reading/writing the plant’s control devices and Reflective Memory’s memory.