A Method for Controlling the Thickness Accuracy of Medium and Heavy Plate

Abstract

The invention provides a thickness accuracy control method for a medium-thickness plate. In the method, various influence factors and constraint conditions are comprehensively considered, various measures such as setting, actual measurement, metering and the like are specially and comprehensively utilized, and five control measures, i.e., thickness control of a steel plate in the length direction, thickness control of the steel plate in the width direction, absolute thickness control of the steel plate, accuracy control of a thickness meter and secondary rolling target thickness control are performed, so that the model accuracy is more practical, the application design is more scientific, the hardware setting and functions are more standard, optimization of a target thickness is realized under the condition of meeting the constraint conditions, the rolling thickness accuracy of the steel plate is increased remarkably, the surface quality is improved, the depth of a recess is reduced from 0.5 millimeter to 0.13 millimeter, the rolling size spot rate is reduced by 0.76 percent, the yield is increased by 0.80 percent, and remarkable economic benefit and popularization value are achieved.

Description

technical field [0001] The invention belongs to the field of automatic control methods for steel rolling, and in particular relates to a method for controlling the thickness accuracy of a four-high rolling mill with automatic reduction in the rolling process of medium and thick plates. Background technique [0002] With the vigorous development of shipbuilding, bridges, pipes, containers and other industries, plate products have higher and higher requirements for dimensional accuracy, and users have also put forward stricter ordering standards, especially the formulation of the national size standard GB709-2006, so that The tolerance zone is more than 20% stricter than the standard of the old version. At the same time, fierce market competition and rising raw material costs lead to a rapid increase in the production costs of finished products. In this context, further reducing costs and improving product accuracy are not only the basic conditions for occupying a dominant po...

AI Technical Summary

Problems solved by technology

[0004] 1. Thickness problem in the length direction of the steel plate: the current international popular thickness control mode for medium and heavy plates is the absolute AGC (roll gap automatic control system) control mode. The disadvantage of this mode is that when the rolling force at the head of the steel plate fluctuates greatly , the actual rolling force will have a large deviation from the calculated rolling force, and the AGC will inevitably produce a hysteresis overcompensation phenomenon, resulting in a lagging thin spot on the steel plate

Due to the large fluctuation of the rolling force at the head and tail of the steel plate, some points at the head and tail of the steel plate exceed the standard

[0005] 2. Thickness problem in the width direction of the steel plate: On a flat roll mill with a roll body length greater than 4 meters, the excessively long roll body will inevitably produce huge deflection during rolling, resulting in excessive convexity of the steel plate

[0006] 3. The accuracy of the absolute thickness of the steel plate: the accuracy mainly depends on the accuracy of the rolling mathematical model, and the calculation accuracy of the mathematical model mainly depends on the calculation accuracy of the deformation resistance. Usually, the deformation resistance cannot be measured and can only be fitted by experience. Therefore poor precision

[0007] 4. Accuracy of thickness gauges: In the world, gamma-ray thickness gauges are mainly used for thickness measurement of medium and heavy plates, but some domestic thickness gauges purchased from abroad only provide hardware, so they can only develop software independently

[0008] 5. The problem of the target thickness of the secondary rolling: the rolling target thickness must reasonably consider the upper and lower limits of the standard, the material tolerance zone of the billet, the difference between the same plate, the difference between the different plates, and the accuracy of the equipment, while the original method relies on human experience setting, cannot fully take into account the above constraints

[0009] The existence of the above problems has greatly affected the thickness accuracy of the steel plate and the qualified rate of product quality, resulting in a decline in the steel plate rolling yield and a substantial increase in the size spot rate, which directly affects the economic benefits of the enterprise

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