Automation and computer control of continuous casting

 

Automation and computer control of a continuous caster operation is a rapidly evolving development which has a beneficial effect on productivity and product quality.

 

One type of computer control system consists of individual subsystems called level 1 control. These subsystems may then be integrated by process data communication lines between these subsystems, between the subsystems and a supervisory computer (called a level 2 control), and to other plant operations. The supervisory computer provides mainly the function of coordinating all the data communication.

 

In this caster‑operation control system, measurements are made of selected operating parameters to be controlled and regulated. Appropriate control changes are then effected, if required.

 

One main control function is automatic casting. This function may be affected by control and regulation of operation parameters, such as the control of liquid steel level in the tundish by regulating the steel flow from the ladle. Maintaining control of this level assists in the control of the liquid level in the mold, which may be performed by regulating the flow from the tundish. Maintaining control of the liquid level in the mold by means of thermocouples, radiation detectors, eddy current meters, etc, permits control of the caster speed by regulating the speed of the drive motors in the roll containment system. In addition, controlling the loads on these motors provides for the proper load distribution to minimize the occurrence of deleterious tension stresses in the strand skin while casting.

 

Another major function is the control of the cooling rate distribution in the secondary cooling system. This function is usually affected by controlling the strand surface temperature (measured by thermal radiation detectors or thermocouples) by regulating the water-spray flow distribution. Normally, both the casting speed and steel grade bring about changes in the cooling‑control‑settings. Other functions that may be controlled are: mold power additions to the liquid steel surface in the mold; cutting the cast steel shapes on the run‑out tables to the proper length; and strand marking with the proper identification.

 

Further functions of the casting control systems consist of those for all the systems, such as scheduling, life data, chemistry, personnel, and process modeling, etc. See our paper in the Automation category of the Tech Resource section, such as Multi-Level automation system in Steel Industry.