Tandem Roll Train Cascade Control via Regulating Factor K
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Solution Overview
Problem
In tandem roll trains, cascading speed adjustments cause interference in strip tension, particularly when coupling a continuous annealing line with a tandem cold mill, as existing decoupling methods like loop accumulators are insufficient to maintain constant strip speed and tension.
Innovation Solution
A method and control device that adjust the action direction of cascade control using a regulating factor (K) to split speed corrections proportionally between upstream and downstream cascading, with the option to change the master drive as needed, and stabilize strip thickness by measuring properties like thickness between roll stands, ensuring constant strip speed and tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If loop accumulators are used to decouple system parts, then strip speed changes can be counteracted, but decoupling is insufficient to transport the strip without interference through the continuous annealing line
Solution Approach 1:
The patent implements dynamic adjustment of the regulating factor K that can vary between 0 and 1, allowing the cascade control to adaptively change its action direction based on real-time system conditions. This dynamic parameter enables the system to switch between upstream and downstream cascading modes, providing flexible control that overcomes the rigid decoupling approach of traditional loop accumulators.
Solution Approach 2:
The invention changes the control parameter K to transform the cascade control behavior. By adjusting K within the range [0,1], the system can modify the proportion of speed corrections applied to upstream versus downstream drives, thereby changing the effective action direction of cascade control to optimize strip transport through the continuous annealing line.
2Speed
If cascade control is used to adjust drive speeds, then speed coordination between drives is improved, but interference in strip tension occurs
Solution Approach 1:
The patent introduces a adjustable regulating factor K that modifies the cascade control equations. By changing K, the system can control the distribution of speed corrections among drives, thereby adjusting the cascade action to maintain strip tension stability while preserving speed coordination benefits.
Solution Approach 2:
The system dynamically adjusts the cascade control action direction based on real-time conditions. When K=0, upstream cascading is applied; when K=1, downstream cascading is applied. This dynamic switching allows the system to maintain speed coordination while minimizing tension interference by selecting the appropriate cascading direction.
3Ease of operation
If the action direction of cascade control is fixed, then control simplicity is maintained, but adaptability to different system conditions is reduced
Solution Approach 1:
The patent maintains control simplicity by using a single regulating factor K that can be adjusted within a defined range. This parameter change approach allows the system to adapt to different conditions (upstream or downstream cascading) without requiring complex control logic or multiple independent control systems.
Solution Approach 2:
The system achieves adaptability through dynamic adjustment of the regulating factor K. The controller can modify K based on system conditions, enabling the cascade control to adapt its action direction while maintaining a unified and relatively simple control structure. This dynamic parameter adjustment provides versatility without sacrificing operational simplicity.
Data Source
AI summary
A method is disclosed for actuating a tandem roll train, in particular a cold-strip tandem roll train, for producing a strip, e.g., a metal strip, wherein a plurality of drives are provided in a production direction of the strip, the speeds of which drives are adapted via cascade control by way of a master drive, wherein a property of the strip is determined and the direction of action of the cascade control is changed depending on said property, by a control factor (K) being provided, by way of which the direction of action of the cascade control is changed, wherein 0≦K≦1, and wherein if 0<K<1 the action direction is split proportionally between upstream cascading and downstream cascading.