The Application Of Mathematical Model In The Control Of Special Metal Pickling Line

In the iron and steel metallurgy field, the steel pickling, which is a key process for cold rolling production, is an indispensable process in the steel surface treatment field. With mechanical and chemical treatment, the main function of steel pickling is to remove sheet iron and dirt, which generate from hot rolling process, on the strip surface to get a clean strip surface. In order to shorten pickling time, improve pickling quality, reduce waste acid pollution, this paper proposes to control acid concentration, temperature, turbulence, and the new amount of acid, thus achieving better surface treatment based on the mathematical model.In 2010 Baosteel Special Steel business unit put the special nickel-titanium alloy strip cold rolling line into operation. The pickling line takes the Hot & Cold continuous pickling line (referred HCPL) into action, and chooses the mixed acid light tank turbulence pickling process. The process control of the pickling tank uses PID control; the result is not very satisfactory when put into production. With the solving of practical problems as a starting point, this paper combines the mathematical model control with PID to seek a better control method on-site.This article focuses on analysis of the relationship among acid temperature, concentration, turbulence, strip quality, acid solubility and metal ions in the pickling line, and shows that for control of these parameters the traditional single-loop PID control is difficult to achieve the requirements.In the control method, this article studies the current advanced technology in domestic and abroad, discusses PID control theory and method, investigates the strengths and weaknesses between the PID control system and the model control system. This paper proposes the combination between mathematical models with PID control theory methods, integrates the PID control strengths, namely simple calculation, high reliability, small steady-state error with mathematical models strengths, namely pre-planned, stability, gives a new type mathematical model - PID compound control system. And under the Siemens7-400 control system, we complete a specific implementation and solve the insufficient control stability problem in pickling line effectively.Production practice shows that the system is stable and reliable. Base on the Process requirement, he proposed control system satisfies production requirements, improves the quality of pickling strip, and reduces the cost and the labor intensity at the same time, which achieves the planned results.