Cold Rolling Mill Strip Feed Paths for Induction Preheating
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Solution Overview
Problem
Discontinuous cold rolling mills face challenges in rolling brittle and fragile steel strips without inducing strip cracks, particularly in compact systems where space for heating devices is limited, leading to increased off-gauge length and scrap production.
Innovation Solution
Implementing a method where the second steel strip is heated using an induction heater, with the heating device placed along the second path that is longer than the first path, allowing preheating before reaching the roll stand, thereby reducing brittleness and the risk of strip cracks without enlarging the off-gauge length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a heating device is arranged in the first path to heat the steel strip before rolling, then the brittleness of the steel strip is reduced and strip cracks are prevented, but the structural space required is considerable and the off-gauge length increases
Solution Approach 1:
The patent makes the heating device movable rather than fixed, allowing it to be positioned only when needed for heating brittle steel strips. The heating device can be moved into the first path during heating operations and retracted otherwise, dynamically adapting the system configuration to reduce off-gauge length while maintaining heating capability when required.
Solution Approach 2:
The heating device is positioned in advance before the steel strip enters the heating zone, allowing preheating to occur before rolling. This preliminary heating action reduces brittleness and prevents strip cracks during the subsequent rolling operation, addressing the reliability issue while controlling space requirements through precise timing of the heating action.
2Length of stationary object
If the cold rolling mill is designed with a compact structure to minimize off-gauge length, then space is saved, but there is insufficient space to arrange a heating device upstream of the roll stand
Solution Approach 1:
The heating device is designed with movable components that can be positioned into the available space only when needed. This dynamic configuration allows the compact rolling mill structure to be maintained while still accommodating the heating device during operations requiring heat treatment of steel strips.
Solution Approach 2:
The heating device utilizes vertical or lateral space dimensions rather than only horizontal space, allowing it to be arranged in three-dimensional space around the roll stand. This dimensional approach enables the heating function to be integrated into the compact structure without increasing the horizontal footprint and off-gauge length.
3Ease of manufacture
If the first uncoiling reel is positioned far away from the roll stand to accommodate a heating device, then the heating device can be arranged, but the conversion work is extensive and the off-gauge length of all steel strips increases
Solution Approach 1:
Instead of permanently positioning the uncoiling reel far from the roll stand, the heating device is made movable to approach the steel strip when needed. This dynamic arrangement eliminates the need for extensive structural modifications and maintains a compact mill layout while still providing heating capability for brittle steel strips.
Solution Approach 2:
The heating device acts as an intermediary element that can be temporarily introduced into the steel strip path between the uncoiling reel and roll stand. This intermediary approach provides the necessary heating function without requiring permanent reconfiguration of the mill layout or increasing the distance between the uncoiling reel and roll stand.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces the risk of strip cracks in brittle steel strips during cold rolling, maintains a small off-gauge length, and is cost-effective, with the induction heater being simple, reliable, and robust, while protecting the heating device from damage.
Implementation Method 1
the second steel strip is heated while it is being fed to the roll stand
Data Source
AI summary
A first steel strip and a second steel strip (7) are rolled in succession in at least one roll stand (1) of a cold rolling mill. A rolling pause, in which no steel strip is rolled, is provided between the rolling of the first and the second steel strip (7). The first steel strip is fed over a first path starting from a first pay-off reel (2), and the second steel strip (7) is fed over a second path starting from the first pay-off reel (2), or from a second pay-off reel different from the first pay-off reel (2). The first steel strip is not heated as it is fed to the rolling mill (1), whereas, by contrast, the second steel strip (7) is heated. The second path is longer than the first path.