Hot Rolling Mill Roll Crossing for Low-Thrust Shape Control
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Solution Overview
Problem
Conventional hot rolling mills face challenges in controlling the shape of hard steel strips, particularly with small-diameter work rolls, due to excessive thrust forces and limited controllability of quarter buckles, and struggle to achieve wide control ranges and high responsiveness.
Innovation Solution
The proposed method involves adjusting the angles of the upper and lower work rolls and backup rolls to maintain parallel pairs, followed by controlled actuation of horizontal actuators to achieve a slight cross angle, reducing thrust forces and enabling wider control ranges and responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If work-roll crossing is used to increase cross angle for crown control, then responsiveness is improved, but thrust forces between backup rolls and work rolls increase excessively
Solution Approach 1:
The patent divides the roll system into independent work-roll units that can cross relative to the backup rolls without moving the backup rolls themselves. This segmentation allows the work rolls to be independently controlled, enabling crown control through work-roll crossing while avoiding the excessive thrust forces that would otherwise be generated on the backup rolls.
2Ease of manufacture
If small-diameter work rolls are used to reduce rolling load, then manufacturing cost is reduced, but thrust forces become excessive making adoption difficult
Solution Approach 1:
By segmenting the roll system and allowing independent work-roll crossing, the patent enables the use of small-diameter work rolls without generating excessive thrust forces on the backup rolls. The independent control of work rolls relative to backup rolls eliminates the force constraint that would otherwise prevent the adoption of smaller, more cost-effective work rolls.
3Adaptability or versatility
If pair cross mills are used for shape control, then control range is widened, but responsiveness deteriorates due to movement of backup rolls
Solution Approach 1:
The patent segments the roll system into independently controllable work-roll units that can cross relative to stationary backup rolls. This allows the work rolls to be quickly adjusted for crown control without the inertia and complexity of moving backup rolls, achieving high responsiveness while maintaining wide control range through the independent work-roll crossing capability.
Data Source
AI summary
Angles of an upper-side pair of an upper work roll 110A and an upper backup roll 120A, and a lower-side pair of a lower work roll 110B and a lower backup roll 120B are adjusted in a state where the upper-side pair is kept parallel and in a state where the lower-side pair is kept parallel. Thereafter, work-roll pressing apparatuses 130A and 130B, work-roll position control apparatuses 140A and 140B, backup-roll pressing apparatuses 150A and 150B, and backup-roll position control apparatuses 160A and 160B are controlled such that the angles of the upper work roll 110A and the lower work roll 110B are adjusted in a state where the angles of the upper backup roll 120A and the lower backup roll 120B are maintained.