There are many factors that can cause deviations in the thickness of the product during the production process of aluminum foil, including: thickness deviation caused by the previous process, mechanical and hydraulic frame elasticity, roll eccentricity, thermal expansion and wear of the roll system, and roll bearing clearance. The influence of model accuracy, calculation error, response time, and sampling time in terms of electrical control, as well as the influence of reduction amount, deformation rate, work hardening, changes in rolling speed and tension, cooling, etc. in terms of production process.
Causes changes in the elastic deformation of the machine base. Changes in the elastic deformation of the machine base directly affect the roll gap value, causing changes in the thickness of the rolled piece. During the rolling process, if the roll gap can be adjusted in time so that the roll gap adjustment can partially or completely offset the elastic deformation of the stand caused by changes in rolling force, the thickness deviation of the rolled piece can be reduced or even completely eliminated.
Modern aluminum rolling mills are equipped with automatic thickness control systems. The principle is to control the equivalent stiffness of the rolling mill stand through a hydraulic pressure system to control the roll gap and ultimately control the thickness of the strip. Automatic control systems (i.e. AGC systems) are generally divided into three systems:
(1) Thickness gauge part, detects the actual thickness of the strip. At the production site, operators determine whether the thickness control is abnormal based on whether the actual measured curve displayed by the thickness gauge is within the deviation control range.
(2) The thickness comparison and adjustment part mainly compares the actual thickness of the detected strip with the set thickness, obtains the thickness deviation value, and outputs the roll gap adjustment signal.
(3) The roll gap adjustment part mainly adjusts the roll gap through the hydraulic cylinder according to the roll gap adjustment signal to eliminate or reduce the longitudinal thickness deviation of the strip.
It is generally easy to associate the cause of abnormal thickness deviation with the thickness control system itself. In fact, the effectiveness of the thickness control system is not only related to itself, but also depends on the thickness quality of each system of the rolling mill, including the thickness of the billet. If the thickness deviation is caused by the above If the influence of factors exceeds the range required by the thickness control system, the thickness deviation will exceed the requirements.
