Automated Tracking System for a Continuous Rolling Mill

Continuous rolling mills are main suppliers of finished products of the metallurgical industry. To satisfy the requirements of the market, the range of their products must be as wide as possible within the processing capabilities. This requires frequent mill set-up and complicates preproduction process. Application of modern hardware allows to introduce automation into the roll pass design and mill set-up processes.

Engineers of RPC "Donix" developed and introduced into commercial operation an automated tracking system for the production process on the continuous rolling mill 250 in Queenborough (Great Britain).

The system includes (Fig. 1) the main data acquisition unit for speeds and currents of electric drives of rolling stands and auxiliary machinery, the operator's console and the foreman's computer. Special programs "Set-up Tables Editor" and "Trends Viewer" were developed for the users. The software includes rolling programs editor, recorded data viewing and data processing program, software for the equipment operation parameters visualization and data base generation. During the preproduction process a process flow-sheet containing the data about the rolled stock dimension-type, shape and dimensions of rolling stands passes, about roll gap sizes and metal exit speeds is generated on the foreman's computer.

Before rolling the process database is complemented with the roll diameter values, which are used to calculate the required angular rates of electric drives rotation.

The calculated values are displayed on the operator's console as numerical values and graphs, together with the actual values. That significantly facilitates the set-up process.

During rolling the operator can control the electric drives currents and speeds values which are displayed as bar graphs (Fig. 2) or real-time trends (Fig. 3). To detect the looping or tension modes the system controls and compares the stands processing time. The information about the deviation of the rolling schedule from free rolling is displayed on the operator's console by corresponding symbols.

Under conditions of stable operation, all the above-mentioned process variables can be stored and used for further cases of the same products rolling.

The system automatically counts the rolled bars and registers the duration of the equipment downtime periods.

In case of emergency situations (cobbles, equipment failure), all the current variables (within 3 minutes before the event) are stored to the data base at the operator's command. This information can be retrieved and viewed to detect the reasons of failure. At the end of the day shift all the accumulated data will be stored to the report text file at the operator's command.

The hardware and basic operational systems of the units were chosen in accordance with the current tasks. A single-board industrial computer PCA-6772F-Q1A1 is used in the main unit, the computer is mounted in an IPC-6806S (Advantech) cabinet and is equipped with an uninterruptible power supply. A high-performance PCL-818L-A6 board of the analog-digital converter (ADC) transforms normalized analog signals into digital signals. Normalizing converters SCM5B41-03 (Data forth) are mounted on four SCMPB02-3 panels. They are connected with the ADC through ADAM-3937-A terminal board. SCMXPRE-003 power supply provides the voltage required for the SCM5B41-03 converters operation.

All the above-mentioned modules are mounted in Rittal AK 1652.600 cabinet, which is installed in the main control pulpit room. The industrial flat-panel FPM-3176TVR monitor, the KS801 keyboard (Indukey) and the protected KH8243 mouse are used to realize the operator's interface. They are placed on a separate, convenient spot of the control pulpit room. The communication between the main module and the mill foreman's PC is realized through a local Ethernet. All the input signals for the system operation are received as voltages from corresponding electric drives.

The main module controller operates in real-time mode. It collects data about 64 main and 8 additional signals with a frequency of 100 Hz, stores and visualizes them, and also realizes the operator's interface and network functions. Neutrino real-time operational system is used in the main controller to ensure stable performance. The system was developed by "QSSL" (Canada). A conventional Windows operational system is used on the mill foreman's computer. Photon graphics editor was used to design the operator's interface.

Figure 1. Structure chart of the system.

Figure 2. Main window of the operator's interface

Figure 3. Representation of the drives currents and speeds as time trends.

The implementation of the automated tracking system for the production process on a continuous rolling mill allowed:

to facilitate generation of the rolling programs data base and to improve it;
to reduce the mill set-up time when changing for a new product;
to facilitate the drives speed schedules set-up and to make it more accurate;
to reduce the time for searching the reasons of stable rolling schedule disturbances.

As a final result, the performance and efficiency of the rolling mill were increased.