Walking-Beam Furnace Slab Positioning to Minimize Scab Defects

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Solution Overview

Problem

Existing methods fail to effectively design slab length and charging position to minimize scab defects in walking-beam heating furnaces, which occur due to creep deformation and skid contact, particularly in grain-oriented electrical steel sheets.

Innovation Solution

A method using mixed integer programming to determine slab length and charging position, incorporating constraint equations for overhang amount, scab defect probability, and evaluation functions to minimize defect occurrence, considering lead and tail end overhang amounts and skid arrangements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the slab length is increased to reduce overhang amount, then scab defect occurrence is reduced, but flexibility in slab length adjustment is limited

Engineering Contradiction:
Improvescab defect occurrenceVSAvoidslab length adjustment flexibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies parameter changes by systematically varying slab length and charging position as controllable parameters to optimize the overhang amount. By treating these as adjustable parameters rather than fixed values, the method achieves both reduced scab defects and maintained flexibility in adaptation to different heating furnaces and steel grades.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements dynamics by enabling real-time adjustment of slab length and charging position based on actual heating furnace conditions, skid arrangements, and production requirements. This dynamic optimization approach allows the system to adapt to changing conditions while maintaining optimal overhang control to prevent scab defects.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If the overhang amount is increased for longer slabs, then charging flexibility is improved, but creep deformation and scab defects increase

Engineering Contradiction:
Improvecharging flexibilityVSAvoidscab defect occurrence
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent uses parameter changes to dynamically adjust the relationship between slab length and charging position. By optimizing these parameters together rather than independently, the method achieves charging flexibility for various slab lengths while simultaneously controlling overhang amount to minimize creep deformation and scab defects.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies preliminary action by pre-calculating and determining the optimal slab length and charging position before charging operations. This advance optimization ensures that even when accommodating longer slabs with increased overhang, the parameters are set to minimize creep deformation effects and prevent scab defects from the outset.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If different slab lengths are used for different heating furnaces, then each furnace can be optimized, but design complexity increases

Engineering Contradiction:
Improveheating furnace optimizationVSAvoidslab length design complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by establishing systematic relationships between heating furnace characteristics, skid arrangements, and optimal slab parameters. Rather than creating complex custom designs for each furnace, the method uses parameter optimization based on furnace-specific data to achieve both customization and design simplicity through a unified optimization framework.

Inventive Principle:
Principle #35Parameter changes

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

Reduces the probability of scab defects, improving yield rates by optimizing slab positioning and length to minimize scab defects.

Implementation Method 1

the slab may droop due to creep deformation from the support point to the leading/tail ends

Methodology Applied
Scientific EffectCreep deformation: Creep

Data Source

PatentEP4663780A1Method for determining slab length and charging position of slab in walking beam furnace
Publication Date: 2025.12.17 JFE STEEL CORP
  • EP4663780A1 patent drawingFigure 1
  • EP4663780A1 patent drawingFigure 2~3
  • EP4663780A1 patent drawingFigure 4

AI summary

A method of determining the slab length and charging position of a slab in a walking-beam heating furnace uses a constraint equation defining an overhang amount, a constraint equation defining a scab defect occurrence probability corresponding to the overhang amount, and a constraint equation defining upper and lower limits of the slab length, and determines the length of the slab and the charging position of the slab. As the overhang amount, a lead end overhang amount, defined as a distance between a lead end coordinate of the slab in the heating furnace and a second skid coordinate counted from a lead end in a tail end direction, and a tail end overhang amount, defined as a distance between a tail end coordinate of the slab in the heating furnace and a second skid coordinate counted from a tail end in a lead end direction, are used.