Press-Formed Part Rigidity Analysis for Springback Suppression

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Solution Overview

Problem

Current springback reduction technologies are limited in effectiveness and cost, with existing methods failing to provide reliable solutions for reducing springback in press-formed parts, especially for high-strength steel sheets used in automotive applications, and the efficacy of cause analysis measures is uncertain.

Innovation Solution

The method involves forming an analytic model of the part with plane and/or solid elements, setting it to a stressed state that causes springback, detecting the portion that highly contributes to rigidity through optimization analysis, and improving the rigidity of that portion to directly address the springback issue.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a high-strength steel sheet is used to reduce weight and increase strength, then the strength and rigidity of the automotive body is improved, but a large amount of springback occurs during forming

Engineering Contradiction:
ImprovestrengthVSAvoidspringback
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The invention applies a compressive force to the vertical wall portion immediately after the bending step is finished, before the springback can fully occur. This preliminary action counteracts the elastic recovery that would otherwise happen, effectively reducing springback while maintaining the high strength properties of the steel sheet

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention applies a compressive force that acts in the opposite direction to the springback deformation. By applying this counteracting force at the critical moment after bending, the elastic recovery is suppressed and the desired shape is maintained

Inventive Principle:
Principle #9Preliminary anti-action

2Manufacturing precision

If a special die for press forming is manufactured to reduce springback, then the springback reduction effectiveness is improved, but the manufacturing cost increases

Engineering Contradiction:
Improvespringback reduction effectivenessVSAvoidmanufacturing cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

Instead of manufacturing a special expensive die, the invention uses a standard die combined with a compressive force application mechanism. This approach creates the necessary springback reduction effect without requiring a custom-designed die, significantly reducing manufacturing costs while maintaining effectiveness

Inventive Principle:
Principle #26Copying

3Measurement precision

If cause analysis of springback is performed separately from measure implementation, then the analysis can be completed, but the efficacy of the measure is uncertain

Engineering Contradiction:
Improvecause analysis accuracyVSAvoidmeasure efficacy
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The invention merges the cause analysis and measure implementation into a unified process. The compressive force is applied at the specific moment and location identified as critical for springback, directly addressing the root cause while ensuring the measure's effectiveness through integrated design

Inventive Principle:
Principle #5Merging (Combining)

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 allows for a direct and effective reduction of springback, improving the rigidity of the part and the vehicle body, while also reducing the cost associated with special dies and enhancing the reliability of springback reduction measures.

Implementation Method 1

a phenomenon, specifically, a large amount of springback occurs in the steel sheet during forming

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

forming simulation method of an elastic-plastic material

Methodology Applied
Scientific EffectPlasticity: Plasticity

Data Source

PatentEP2891529B1Springback suppression countermeasure method and analysis device for press-formed object
Publication Date: 2023.08.16 JFE STEEL CORP
  • EP2891529B1 patent drawingFigure 1
  • EP2891529B1 patent drawingFigure 2
  • EP2891529B1 patent drawingFigure 3~3(b)

AI summary

A method for reducing springback in a press-formed part according to the present invention includes an analytic model forming step for forming an analytic model of the part from plane elements and/or solid elements; a stressed-state setting step for setting each of the elements of the analytic model to a stressed state that causes a springback; a rigidity-contributable-portion detecting step for performing an optimization analysis for shape on the analytic model with the elements set to the stressed state in the stressed-state setting step to detect a portion of the part that highly contributes to the rigidity thereof; and a rigidity improving step for applying a rigidity improving means to the part on a basis of the portion detected in the rigidity-contributable-portion detecting step.