Cold rolling production technology and development direction

The main direction of development of cold-rolled strip production technology is to continuously improve product quality, mainly strip thickness accuracy and plate shape flatness. In order to meet the stringent requirements of modern automatic flow production and improve market competitiveness. For example, it is required that the thickness of the same plate of automobile panels should not be greater than ±5μm, the flatness of the plate shape should be increased from 20I to 10I (1I unit = 10-5 relative length difference), the requirement of tin-plated plates should be 5I, and the plate convexity should also be within the original 30μm. Around 10μm. This will inevitably require greater progress in quality control technology. Automatic thickness control (AGC) technology has developed to a very high level in the past 20 years. The longitudinal thickness deviation of cold-rolled strip steel has been reduced from ±3% to ±1%-2%, and the absolute deviation value has been reduced from 5 μm to 2 μm. The development trend of AGC systems is to use computer digital direct control (DDC-AGC), and some of its links are still being improved, mainly including:

Further improve calibration accuracy
Feedforward and feedback control
Eliminate the influence of support roller eccentricity on thickness
Automatic adjustment system control accuracy The main directions are:
(1) HC mill with axial movement of the intermediate roll and HVC mill with increased horizontal movement of the work roll.
(2) VC rolling mill with variable support roll crown.
(3) Pc rolling mill with crossed rollers.
(4) FFc rolling mill with vertical and horizontal bending of work rolls (developed in Japan above).
(5) CVC rolling mill that continuously changes the roll convexity.
(6) UPC mill with axially moving cigar-shaped work rolls.
(7) NIPCO roll with roll gap control.

At present, the most commonly used rolling mills in China are six-roller HC mills and concave-roller CVC mills. HC or improved UC rolling mills are often used in new construction. CVC or UPC can be used during renovation. The shape control range of HC mills is larger than that of CVC. Therefore, the application rate of using HC rolling mill to improve plate shape is about 80%, while that of CVC is 10%. At present, there is more trend towards the joint application of these two flat shape control technologies, such as six-roller CVC; and CVC-HC technology.