Rolling Mill Intermediate Roll Offset Control
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Solution Overview
Problem
The reduction in work roll diameters in rolling mills leads to insufficient spindle strength, causing deflection and instability in the rolling process due to torque imbalances between upper and lower intermediate rolls, which results in poor strip shape quality and potential sensor breakage or erroneous detection.
Innovation Solution
A rolling mill configuration with upper and lower intermediate rolls having tapering sections, position adjusting means, detecting means for horizontal forces, and controlling means to offset the intermediate rolls based on calculated offset amounts, ensuring balanced torque distribution and minimizing deflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the diameter of work rolls is reduced to reduce rolling load, then the rolling load is reduced, but the spindle strength becomes insufficient causing work roll deflection
Solution Approach 1:
The rolling mill employs a segmented roll structure with work rolls, intermediate rolls, and backup rolls. The intermediate rolls support the work rolls and distribute the rolling load, preventing excessive deflection even when work roll diameters are reduced. This segmentation allows smaller work rolls to be used while maintaining structural integrity through the supporting intermediate and backup roll systems.
Solution Approach 2:
The patent implements dynamic offset control of intermediate rolls based on detected work roll deflection. The intermediate rolls are positioned with adjustable offsets in the rolling direction, and this offset is dynamically controlled based on feedback from deflection detection. This dynamic adjustment balances the torque distribution and compensates for spindle strength limitations, allowing reduced work roll diameters without excessive deflection.
2Adaptability or versatility
If intermediate-roll drive is used to enable reduced work roll diameter, then work roll deflection can be controlled, but torque circulation causes up to 30% difference in drive torque between upper and lower sides
Solution Approach 1:
The patent employs feedback control by detecting work roll deflection (horizontal displacement) and using this information to adjust the offset position of intermediate rolls. Deflection detection means measure the actual deflection, and this feedback is used to dynamically position the intermediate rolls to balance the torque distribution between upper and lower sides, compensating for the torque circulation effect.
Solution Approach 2:
The intermediate rolls are designed with dynamic offset capability in the rolling direction. The offset position is not fixed but can be adjusted based on rolling conditions and detected deflection. This dynamic positioning allows the system to adapt to torque circulation effects and maintain balanced torque distribution between upper and lower intermediate rolls, achieving precise torque control despite the 30% difference potential.
3Measurement precision
If gap sensor is placed on the horizontal side surface of work roll to detect horizontal deflection, then detection accuracy is improved, but the sensor may break due to strip breaking or give erroneous detection in coolant environment
Solution Approach 1:
The patent uses an intermediary approach by detecting work roll deflection indirectly through the position of intermediate rolls rather than placing sensors directly on work rolls. The intermediate rolls serve as mediators that reflect the work roll deflection state, allowing deflection detection without exposing sensors to the harsh environment of direct contact with rolling material and coolant, thus maintaining both accuracy and reliability.
4Force
If the diameters of work rolls are reduced, then rolling load is reduced, but the strip shape deteriorates due to work roll deflection
Solution Approach 1:
The patent implements dynamic offset control of intermediate rolls to maintain work roll parallelism and prevent deflection-induced shape deterioration. By adjusting the offset position of intermediate rolls based on detected deflection, the system dynamically compensates for the reduced stiffness of smaller work rolls, ensuring uniform rolling pressure distribution and maintaining good strip shape even with reduced work roll diameters.
Solution Approach 2:
The patent changes the operational parameters of the intermediate rolls by introducing and adjusting offset distances in the rolling direction. This parameter change allows the intermediate rolls to compensate for the reduced structural rigidity of smaller work rolls, maintaining proper contact pressure distribution across the work roll surface and preventing shape defects in the rolled strip.
Data Source
AI summary
A rolling mill includes: work rolls configured to roll a rolling material; intermediate rolls supporting the work rolls from above and below, respectively; back-up rolls supporting the intermediate rolls from above and below, respectively; position adjusting means for adjusting the positions of the intermediate rolls relative to the work rolls and the back-up rolls in the direction of conveyance of the rolling material; detecting means for detecting horizontal forces on the work rolls; offset-amount calculating means for calculating the offset amounts of the intermediate rolls based on the horizontal forces on the work rolls detected by the detecting means; and controlling means for controlling the position adjusting means such that the positions of the intermediate rolls are offset by the offset amounts calculated by the offset-amount calculating means.