ROLLING MILL COILBOX INTERMEDIATE BACKWIND DEVICE
“Coilbox” technology is an intermediate process, aiming at roll winding at a high speed at the outlet from roughing mill group with further material uncoiling at a lower speed and its transfer to finishing mill group. “Coilbox” technology made revolutionary changes in production of steel hot-rolled sheet due to two key principles: temperature keeping and long bars treatment. Coiling process decreases surface area of roll heat emission. As a result, the bar after uncoiling has actually the same temperature as during coiling, which allows to carry out rolling in finishing mills with constant speed.
“Coilbox” technology allows to decrease expenses on power during material rolling in finishing mill group, provides high smoothness of end product metallurgical properties and allows to widen products assortment rolled in mill. In addition, bar coiling can be started when the bar is still in roughing group, thus Zaporozhstal hot rolling mill can treat longer bars. “Coilbox” technology and unit design were considerably updated within the last thirty years, having resulted in high level of efficiency and reliability with stable good quality of manufactured goods and even temperature distribution along the bar.
The following systems are included into “Coilbox” equipment:
- Electric drives system;
- Hydraulic system;
- Greasing system;
- Water cooling system;
- Strip position control sensors system;
- Automated control system of Coilbox intermediate backwind device (further IBD ACS).
Electric drives system is developed on the basis of AC electric drives. It includes 4 group and 8 individual electric drives. For them we’ve made a reservation system on the basis of stand-by frequency converters and reserve switching cabinets. Stand-by switching is possible both in local mode and remotely by “Coilbox” operator. It minimizes downtime coming from possible frequency converter failure.
For drives of hydraulic system pumps we used thyristor starters, which allow to reach pumps nominal operation speed smoothly and shock-free.
IBD ACS consists of 2 levels.
Lower automation level fulfils collection of data from technological sensors, electric drives, operator’s worktable controls and actuates electric drives, executive devices.
The second level is system of data automatic collection, its efficient display and storage, diagnostics, warnings and report documents formation. This level also communicates with hot rolling mill automatic control level via Ethernet network. The second level provides a possibility of human participation in technological process, operational estimation, control, feature determination, events analysis within different intervals with possibility of decision making.
The following main components are included into IBD ACS:
a) Main Master Controller.
This controller communicates with all units of the system, collects data from sensors, drives, operator’s control units, operator’s workstations, from hot rolling mill equipment. It processes the received data on the basis of “Coilbox” operation algorithm, provides issue of control actions for executive devices and drives, provides issue of information signals to operation and engineering stations.
Main master controller backup is provided.
b) Electric Drives Controller.
This controller is connected with master controller, electric drives, electric drives diagnostics station. It is a buffering controller between main master controller and electric drives for transfer of control actions to electric drives and condition signals from electric drives. Electric drives controller is used as electric drives diagnostics station element for formation of emergency trace and data collection from electric drives.
Electric drives controller backup is provided.
c) Workstations ¹1, 2.
These stations function as HMI clients. Stations provide interface between control system and operator via HMI graphic screens (HMI - human-machine interface). For operator it’s necessary to display two different data screens simultaneously, and the second operator’s station services this function acting as another HMI client. In case of engineering station failure this station can fulfill functions of engineering station in the part of programmable logic controller operation.
d) HMI Server.
It is the leading section of SCADA system. The server connects and communicates with programmable logic controller (PLC) via ModbusPlus communication network and other HMI clients via Ethernet TCP/IP network.
e) Engineering Station.
This station is used as a primary technical automated workplace for development of HMI and PLC program. Engineering station can function as stand-by HMI server. Engineering station connects and communicates with programmable logic controller via ModbusPlus communication network and other HMI clients via Ethernet TCP/IP network.
f) Drives Diagnostics Station.
This station is needed for electric drives system diagnostics.
It’s connected with electric drives controller via ModbusPlus network. Human-machine interface software makes monitoring of different "Coilbox" systems current operation, displays for the operator data on current condition of system elements, warning and alarm messages, has archiving function and function of emergency trace forming.
Human-machine interface software is developed for “Coilbox” workstations, electric drives diagnostics station and consists of the following main elements:
- main window – mnemonic diagram, which displays coiling, uncoiling process and “Coilbox” mechanisms condition;
- mnemonic diagrams windows with displaying of electric drives system units;
- settings windows;
- calibration windows;
- signals archive;
- list of events;
- list of active warning and alarm messages;
- archive of warning and alarm messages;
- windows displaying condition of greasing, water cooling systems;
- windows displaying condition of hydraulic system.
Applied solutions of human-machine interface (HMI) organization give "Coilbox" operator and servicing personnel powerful and convenient instrument for operational estimation of the situation in “Coilbox” and hot rolling mill for efficient, effective response to these situations.