Deviation value control method for cold rolling hot galvanizing coating uniformity

Abstract

The invention provides a deviation value control method for cold rolling hot galvanizing coating uniformity. The method comprises the steps of: 1) establishing an influence model of the knife lip opening degree on coating thickness; 2) establishing an influence efficiency function matrix determining the influence weight of each air knife lip servo motor adjustment amount on each coating; 3) solving a motor adjustment amount according to a quadratic error function minimum principle; and 4) considering the actual application features in terms of correcting the quadratic error function, when the galvanizing thickness measured value of a point deviates from most measuring points, in order to avoid the interference of an extreme value on the coating control of other areas, adding a filtering function in an error function, thus finally obtaining a needed air knife lip opening degree. The invention provides a new galvanized layer thickness calculation model suitable for industrial application, introduces the influence efficiency function matrix, enhances the coating uniformity control accuracy, and simultaneously adds the cost function and the filtering function to improve the coating error function accuracy, thereby enhancing the coating uniformity calculation accuracy, and improving the surface quality of a galvanized product.

Description

technical field [0001] The invention belongs to the technical field of automatic control of galvanizing process, in particular to galvanizing process and coating control technology of cold-rolled hot-dip galvanizing line. Background technique [0002] An important technical index to measure the quality of galvanized products is the coating thickness and its uniformity. If the coating is too thick, it will not only waste raw materials such as zinc ingots, but also affect the performance of the product such as spot weldability, adhesion, and powdering resistance of the coating; while the coating is too thin, it will affect the corrosion resistance of the product. will accept. Therefore, the control level of the coating uniformity system will directly affect the product quality, product cost and market competitiveness of the hot-dip galvanized sheet. This puts forward very high technical requirements and control difficulties for the coating uniformity control technology. To o...

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Problems solved by technology

[0003] The Chinese patent with the patent number CN200820151950.4 adopts the dual control strategy of auxiliary air knife + 'V' type baffle, provides a study on the side control device based on the problem of over-galvanizing at the edge of the strip, and proposes a new air knife device scheme, which By changing the size of the baffle at the edge of the air knife and the gap between the baffle and the strip, the influence of the size and gap of the baffle on the thickness of the zinc layer at the edge of the strip is studied under the conditions of certain air pressure and strip width. Its disadvantage is that it only considers the inhibitory effect of the knife lip opening on the over-galvanizing of the edge of the strip, and does not solve the problem of uneven coating thickness at other parts of the strip in the transverse direction, and it only stays in the system simulation stage and has not been put into actual industrial application; The Chinese patent with the patent number CN201110143959.7 relates to a method for precisely adjusting the air knife for controlling the thickness of the galvanized layer, which can prevent nodulation of the air knife. The method includes adjusting the level between the left knife lip and the right knife lip Since the two ends of the plane reference plate are respectively inserted and placed in the left and right knife lips, the inclination angle between the plane reference plate and the horizontal plane measured by the level can directly reflect the left knife lip and the right knife lip. The levelness between the right knife lips ensures the accuracy of the subsequent levelness adjustment. The disadvantage is that it is only a compensation method for the problem of air knife nodules, and does not deal with the lateral uniformity of the coating; the patent number is CN200910131086. 0’s Chinese patent mentions the BP neural network control method for the thickness of electro-galvanized zinc layer and its application on PLC. Interference, intelligent self-adaptation, good accuracy and fault tolerance, the disadvantage is that only considering the average zinc layer thickness, there is no mention of the calculation model and control method of the strip transverse coating thickness

[0004] At present, in most galvanizing production lines at home and abroad, the adjustment of the lateral shape and opening degree of the air knife lip is realized through n manual screw actuators outside the line, and the size and lateral change of the opening degree are set according to production experience. Once it is put into actual production, it cannot be changed dynamically, which seriously restricts the ability to adjust the uniformity of the coating

In addition, even if the DAK air knife is used, the effect of its automatic control of the lip motor to change the uniformity of the coating is not obvious. The value calculation model adopts the method of orthogonal polynomial regression. This algorithm is more complicated, less practical and less accurate. In addition, it does not consider the characteristics of the knife lip adjustment that is too sensitive to the delayed feedback response and the influence of the large deviation of the coating measurement.

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