Rolling Mill Tension Control Using Speed-Based Drive Compensation

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Solution Overview

Problem

Existing tension control methods in rolling mills are often too slow to effectively correct irregularities and disturbances during the rolling process, leading to unstable rolling processes and increased off-gauge lengths of metal strips.

Innovation Solution

The method involves converting the tension controller's output signal into an actuating signal for the rotary drive based on the speed of the metal strip, using a variable amplification factor to pre-control tension disturbances, allowing for faster and more adaptive tension control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the rotary drive of the rolls is used as an actuator for tension control, then the system structure is simplified, but the response speed becomes too slow to correct frequent disturbances

Engineering Contradiction:
Improvesystem structureVSAvoidresponse speed
Core Design Contradiction:
Device complexityVSSpeed

Solution Approach 1:

The invention pre-calculates and stores the relationship between speed deviations and required tension corrections in lookup tables during commissioning. During operation, the controller directly retrieves pre-computed correction values based on measured speed deviations, eliminating the need for complex real-time calculations and enabling fast response without complex computational overhead

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention replaces complex real-time mechanical control calculations with pre-computed lookup tables and simple interpolation algorithms. This substitution of computational mechanics for mechanical control logic enables rapid response by avoiding complex real-time computations while maintaining the simplicity of using rotary drives as actuators

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Stability of the object's composition

If traditional tension control methods are used, then the system is stable, but the commissioning process requires extensive test runs and specialist time

Engineering Contradiction:
Improverolling stabilityVSAvoidcommissioning time
Core Design Contradiction:
Stability of the object's compositionVSLoss of time

Solution Approach 1:

The invention performs all complex system identification and parameter optimization during initial commissioning, storing the results in lookup tables. This preliminary action captures the stable operating characteristics of the system, allowing rapid commissioning without extensive test runs while maintaining rolling stability through the pre-optimized control parameters

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention creates simplified lookup table representations of the complex tension-control relationship during commissioning. These lookup tables serve as copies of the full control model, enabling rapid control decisions during operation without requiring repeated complex testing or specialist intervention, thus reducing commissioning time while preserving stability

Inventive Principle:
Principle #26Copying

Data Source

PatentEP3568243B1Method for tension control
Publication Date: 2021.03.10 SMS GROUP GMBH
  • EP3568243B1 patent drawingFigure 1
  • EP3568243B1 patent drawingFigure 2
  • EP3568243B1 patent drawingFigure 3

AI summary

The invention relates to a method for tension control in a band-shaped material between two tension points, in particular between two adjacent roll stands, wherein at least one of the tension points has a rotary drive as an actuator. In order to make known tension controls of this type more effective and faster, according to the invention, the controller output signal is varied in connection with the conversion thereof into the actuating signal for the rotary drive, at least temporarily, in dependence on a variable representing the band-shaped material.