Best Product Quality and High throughput in Plate Production Based on Model Based Control

摘要

@@ Today's demands on high-strength plate include good weldability and the reduction of costly alloys to a minimum. At the same time, geometry and shape of the plate shall have smallest possible tolerances. The production of such plate is economically possible employing thermomechanical rolling in combination with advanced process control. The use of fully automatic thermomechanical rolling using latest physical models and intelligent sequencing strategies achieves the optimum in grain refinement and thus improves mechanical properties, at the same time keeping productivity high through sophisticated mill pacing. Beside model-based thickness control and plan view pattern control for rectangularity, Profile and Flatness Control (PFC) is crucial for achieving desired dimensions of the plate. It is goal of PFC for plate mills to achieve a flat plate with the desired target profile. At the same time, for profitability of the mill, it is important to work with high throughput, I.e. Large reductions. The novel profile and flatness strategy relies on comprehensive physical models and makes use of SmartCrown?as a powerful actuator, enabling large reductions even in wide plate mills without risking edge waves. The examples are shown from both 1-stand and 2-stand plate mills. The functionality can be easily implemented into existing mills. The philosophy behind Siemens?process control is to employ physical models to describe the mill, the material to be processed as well as their interaction. Artificial neural networks are in use for modeling the influence of chemical composition which only can be described empirically -at least so far. Those neural networks are not simple correction networks but they represent physical parameters such as the yield stress. Because physics is the same at every plant, the models start well conditioned already for the first plate -a pre-requisite for a fast start-up.