Hot-Rolled Strip Flatness Roller Alignment for Stable Strip Run
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Solution Overview
Problem
In hot-rolling mills, the immersion of a flatness-measuring roller in the hot-rolled strip creates a configuration that leads to a high risk of strip departure, especially for strips with low thickness, causing instability in the strip run and disrupting flatness measurements.
Innovation Solution
A flatness-measuring device with at least one entry-side deflection roller, an exit-side deflection roller, and a central deflection roller that can be placed against the opposite side of the hot-rolled strip, equipped with a sensing apparatus and an adjusting apparatus to vary the angle of the deflection rollers and maintain strip center position during measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a measuring roller is immersed in the hot-rolled strip for flatness measurement, then flatness measurement is enabled, but the risk of strip departure increases significantly
Solution Approach 1:
The deflection rollers are made pivotable rather than fixed, allowing them to dynamically adjust their position and angle in response to strip position deviations. This dynamic adjustment capability enables the system to maintain reliable strip run while accommodating the measurement function, resolving the contradiction between measurement capability and strip stability.
Solution Approach 2:
A feedback control system continuously monitors the strip center position and automatically adjusts the deflection rollers to correct any deviations. This closed-loop control ensures that the strip maintains proper alignment during measurement, preventing strip departure while enabling accurate flatness measurement through the immersed roller.
2Ease of operation
If conventional deflection rollers are used in hot rolling with long clamping lengths, then strip guidance is provided, but control effectiveness is reduced due to large dead time
Solution Approach 1:
The pivotable deflection rollers are positioned to act upstream of the measurement point, allowing preliminary correction of strip position deviations before they propagate through the long clamping length. This preliminary action reduces the effective dead time by addressing strip run issues earlier in the process, improving control effectiveness despite the long clamping lengths inherent in hot rolling.
3Measurement precision
If the measuring roller is placed between the cooling section and driver roll, then flatness measurement is possible, but strip departure risk increases due to triple deflection configuration
Solution Approach 1:
The deflection rollers are designed to be pivotable rather than fixed, allowing them to dynamically adapt to strip position variations. This dynamic capability reduces the harmful centering effect disruption caused by the triple deflection configuration, enabling the measuring roller to be immersed without significantly increasing strip departure risk while maintaining measurement capability.
Data Source
AI summary
A flatness-measuring device for a hot-rolled strip within a hot-rolling mill includes an entry-side deflection roller and an exit-side deflection roller. A central deflection roller is arranged between the entry-side deflection roller and the exit-side deflection roller. The central deflection roller is used as a flatness-measuring roller. To prevent the hot-rolled strip from departing laterally during a flatness measurement, the flatness-measuring device has a sensing apparatus for sensing an actual position of the hot-rolled strip. An adjusting apparatus is connected to the sensing apparatus and to at least one of the deflection rollers. The flatness-measuring device is designed to vary an angle between a longitudinal central axis of the deflection roller respectively connected to the adjusting apparatus and a longitudinal axis of the flatness-measuring device based on a deviation of the actual position of the hot-rolled strip from a predefined target position.