Laser Cutting of High-Strength Steel for Accurate Blank Geometry

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Solution Overview

Problem

High strength steel cutting processes face challenges with residual stress relief, leading to poor geometric accuracy and increased process scrap, particularly in cutting long and narrow blanks used in automotive applications like tailor welded blanks.

Innovation Solution

A laser cutting process that involves positioning a mother blank on a moveable cutting table, clamping, cutting, separating, and laser trimming sub-blanks to address geometric issues and improve edge quality and productivity, utilizing magnetic clamping and simultaneous laser trimming of both cut edges to minimize stress-induced deformations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional laser cutting is used on high strength steel, then cutting speed and productivity are maintained, but geometric accuracy deteriorates due to residual stress relief

Engineering Contradiction:
Improvecutting speedVSAvoidgeometric accuracy
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The cutting process is divided into two distinct stages: rough cutting to separate sub-blanks from the mother blank, followed by precise trimming to achieve final geometric accuracy. This segmentation allows each stage to be optimized independently - rough cutting for speed and trimming for precision - thereby resolving the contradiction between productivity and manufacturing precision.

Inventive Principle:
Principle #1Segmentation

2Strength

If high strength steel is used to increase safety performance, then vehicle safety is improved, but residual stress issues worsen leading to poor blank geometry

Engineering Contradiction:
Improveultimate tensile strengthVSAvoidblank geometry
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The rough cutting stage performs preliminary separation of sub-blanks while they are still clamped to the mother blank, preventing stress-induced deformation before it occurs. By establishing the basic geometry under constrained conditions and then performing precise trimming, the process proactively prevents geometric deterioration that would otherwise occur with high strength materials.

Inventive Principle:
Principle #10Preliminary action

3Adaptability or versatility

If long and narrow blanks are cut for automotive applications, then component functionality is improved, but geometric accuracy deteriorates due to stress relief

Engineering Contradiction:
Improvecomponent functionalityVSAvoidgeometric accuracy
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The blank is processed in two stages: rough cutting creates the basic long and narrow geometry, then trimming refines the edges to achieve precise dimensions. This segmented approach allows the creation of functionally required shapes while maintaining geometric accuracy through the subsequent precision trimming stage.

Inventive Principle:
Principle #1Segmentation

4Device complexity

If traditional cutting methods are used, then process simplicity is maintained, but edge quality deteriorates affecting subsequent welding operations

Engineering Contradiction:
Improveprocess simplicityVSAvoidedge quality
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The cutting process is segmented into rough cutting for material separation and trimming for edge quality enhancement. This segmentation enables the use of laser technology in both stages to achieve superior edge quality suitable for welding, while the modular process structure keeps operational complexity manageable.

Inventive Principle:
Principle #1Segmentation

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

The process achieves excellent blank geometry, edge quality, and reduced process scrap by minimizing internal stresses and deformations, enhancing the precision and efficiency of cutting high strength steel materials.

Implementation Method 1

Op3/ cutting, using a laser source, n untrimmed sub-blanks from the mother blank

Methodology Applied
Scientific EffectLaser ablation: Laser Ablation

Implementation Method 2

Op7/ laser trimming the n untrimmed sub-blanks in order to form n trimmed sub-blanks

Methodology Applied
Scientific EffectLaser ablation: Laser Ablation

Implementation Method 3

The clamping operations Op2 and Op6 are performed using magnetic clamping

Methodology Applied
Scientific EffectMagnetic attraction: Magnetism

Data Source

PatentEP4247584B1Process and equipment to laser cut very high strength metallic material
Publication Date: 2025.01.08 ARCELORMITTAL SA
  • EP4247584B1 patent drawingFigure 1
  • EP4247584B1 patent drawingFigure 2a~2b
  • EP4247584B1 patent drawingFigure 3a~3b

AI summary

Laser cutting process to produce n trimmed sub-blanks, n being an integer strictly greater than 1, from a mother blank made of metallic material, comprising the following steps: -Op1/ positioning the mother blank on a cutting table, said cutting table comprising n laths arranged to be moveable relative to one another in a transverse direction, -Op2/ clamping at least part of the mother blank to the cutting table, -Op3/ cutting, using a laser source, n untrimmed sub-blanks from the mother blank in a longitudinal cutting direction, -Op4/ separating the n laths of the cutting table from one another in a transverse direction, -Op5/ releasing the clamping, -Op6/ clamping the n untrimmed sub-blanks to the n laths, -Op7/ laser trimming the n untrimmed sub-blanks in order to form n trimmed sub-blanks, -Op8/ releasing the clamping, -Op9/ discharging the n trimmed sub-blanks from the cutting table.