The Oman Aluminium Rolling Company (OARC) is a state of the art, light gauge, sheet rolling facility in Sohar, Oman. The facility includes a Hazeltt Twin Belt Caster and a state of the art hot rolling, cold rolling and finishing operations for sheet aluminium used in air conditioning, automotive heat exchangers, food containers, foil wrap, pharmaceutical and industrial applications.
The newly built facility required moving structures to transport the coils through complicated path sequences automatically as part of the Aluminium rolling process. The cranes needed to be capable of delivering coils according to the requirement of process machines while achieving the optimum route and not obstructing other cranes, working in the same area.
Fairfields converted a standard manual controlled 25t rated crane into a highly complex, automated aluminium coil handling crane system via PLC controls and a SCADA system.
The automated aluminium coil handling crane system was achieved by a ground-based control and on-board crane control. The ground-based control system monitors the coil requests of various machines, task request lists, sorting them according to their priority and assigning the task to each crane.
The on-board crane controls each crane monitor and controls the crane movement through the optimum possible route based on the task assigned by the ground-based control system. The communication between the ground-based system and on-board crane control systems is achieved via managed switches and a Siemens SCALANCE wireless communication network. Any loss of communication leads to an emergency stop of the crane automatically, thus safety of the system is guaranteed.
The PC-based SCADA provides a graphical representation of the coil storage area, crane operation, missions in the queue and plant device status. The data, such as the coil identification number, weight and next process machine destination of the coils located in the coil storage area, is stored in the ground-based control and can be monitored through the SCADA and the HMI provided on the control desk.
The customer required an intelligent system, which could identify the coil requirements of each processing machine. The developed crane control system needed to be able to sort and prioritise the coil transporting requests of multiple process machines and display the requests via the SCADA. The system records the coil data and time of coil transportation, while achieving the optimum crane movements.
Complicated algorithms had to be developed by the design team to implement the customer requirements. A gate interlock mechanism was also incorporated within the Siemens Safety PLC to ensure operator/engineer safety on site.
The final design achieved a 5mm tolerance for all the crane targets. A coil data backup system was also developed with the help of a dedicated Siemens PLC to retrieve coil data in the coil storage area.