Galvanized steel sheets play a major role in industrial manufacturing, for example in automobile construction. An approved method of protecting the sheets against rust is to apply a zinc coating using the hot-dip galvanizing process. The equipment for this is complex and places high demands on a modern process control system.
Hot-dip coating facility 2 is one of currently eight units of this type at Thyssen Krupp Steel Europe. It is around 300 meters long and has an annual capacity of around 440,000 tons of galvanized steel sheet. The products go mainly to the auto industry. To meet strong customer demand, the plant runs in continuous operation 24 hours a day, seven days a week. The only interruptions are scheduled maintenance shifts every two to three weeks. Since the hot-dip coating line is a bottleneck unit, unscheduled downtimes throw the production schedule into serious disarray. The stockpile would fill up in no time and the production of further coils in the rolling mills would have to be stopped or outsourced. However, the effects would be even more serious at the other end of the process chain: The processing companies themselves hardly keep any buffer stocks because they order the required materials just-in-time. These deliveries to the automotive manufacturers could no longer be serviced in time, which would in turn lead to bottlenecks there.
The process control system is of crucial importance for plant availability. Without an overview from the control room, such a high-tech plant cannot be operated. The existing visualization solution could not be technically expanded, and malfunctions occurred in some cases.
As a process control system, focus relies on the Simatic WinCC V7 Scada system from Siemens, whose scalability also allows the implementation of prospective expanded functions of the hot-dip coating line. The use of the software and the required options in a virtual environment is already tested and confirmed by Siemens during the system test. The process control system is to be as fail-safe as possible: for this reason, it will run on a redundant server. An engineering station will be used for the control system so that adjustments can be made to the WinCC project and tested independently of productive operation.
focus also had to clarify the question of how the existing automation components with the Modbus Plus communication protocol will be connected to the new process control system with Profinet. For this purpose, a Modbus Plus communication card is plugged into each of two additional Simatic IPC547E rack PCs via the PCI bus. Simatic thin clients suitable for industrial use will be used for the most part as operator stations.
Data transfer to the clients is handled by fiber optic cables to eliminate the effects of electrical interference from the plant's many drives. The new process control system is rounded off by a UPS that brings the plant into a safe state in the event of a power failure.
Furthermore, the control views have been significantly streamlined, while at the same time discreetly inserted animations ensure a more intuitive grasp of the process. Access rights define which operator sees which warning or error messages at which station. Remote access to the plant meets today's security standards and takes place via a VPN connection that has to be set up beforehand. Finally, the plant is also connected directly to Thyssen Krupp's ERP system via a serial link so that the plant data is available throughout the company. This means that the production and quality data for each individual coil is available centrally and can be assigned in the ERP system. As a result, detailed long-term evaluations are now possible, which have already led to improvements at the plant and increased productivity.