Press Mold Cushioning for Vertical Wall Warping Control

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Solution Overview

Problem

Existing press-forming technologies face challenges in achieving accurate dimensional precision for hat cross-sectional components without flange portions, particularly due to springback deformation and warping issues in vertical wall portions, especially when using thin high-tensile steel sheets, which are exacerbated by the complexity and risk of die damage in existing countermeasures.

Innovation Solution

A press forming device that applies compression stress to vertical wall portions using stoppers and bending blades to constrain out-of-plane deformation, reducing stress differences and preventing buckling, while adjusting the compression amount through a cushion system to maintain precise control and prevent die damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If compression stress is applied to vertical wall portions to reduce warping, then manufacturing precision is improved, but the risk of die damage increases

Engineering Contradiction:
Improvedimensional accuracyVSAvoiddie damage risk
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

A cushion member is provided between the press and the upper die to absorb excessive impact forces. The cushion member compresses during die closing to provide a cushioning effect that prevents direct transmission of impact loads to the die, thereby reducing die damage risk while maintaining the ability to apply compression stress for warping reduction

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

2Manufacturing precision

If irregular shape connection portions are engaged to prevent buckling, then manufacturing precision is improved, but device complexity increases

Engineering Contradiction:
Improvevertical wall stabilityVSAvoiddie structure complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The function of preventing buckling through complex irregular shape engagement is extracted and replaced by a simpler cushioning mechanism. The cushion member provides the necessary support and stability during compression without requiring complex interlocking geometries between die components

Inventive Principle:
Principle #2Taking out (Extraction)

3Manufacturing precision

If compression amount is increased to reduce warping, then manufacturing precision is improved, but the likelihood of buckling increases

Engineering Contradiction:
Improvewarping reductionVSAvoidbuckling risk
Core Design Contradiction:
Manufacturing precisionVSShape

Solution Approach 1:

The cushion member is positioned to provide support before buckling can occur during compression. As compression force is applied, the cushion member compresses and provides a supporting reaction force that stabilizes the blank, allowing higher compression forces to be applied for warping reduction without causing buckling

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 solution effectively reduces warping and improves dimensional accuracy of press-formed articles by applying controlled compression, allowing for mass production of components with reduced warping and enhanced precision, even with high-tensile steel sheets.

Implementation Method 1

a cushion component sandwiched between the press and the upper die, and having a function of cushioning an impact when the upper die and the lower die are brought close to each other under pressurization

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

applying compression stress to vertical wall portions using stoppers and bending blades

Methodology Applied
Scientific EffectCompression stress: Compression

Implementation Method 3

springback deformation due to elastic recovery occurs in a press-formed article after forming release

Methodology Applied
Scientific EffectElastic recovery: Elasticity

Data Source

PatentEP3603834B1Press mold device and production method for press-molded articles
Publication Date: 2023.08.02 JFE STEEL CORP
  • EP3603834B1 patent drawingFigure 1~2B
  • EP3603834B1 patent drawingFigure 3
  • EP3603834B1 patent drawingFigure 4A~4E

AI summary

To reduce warping of vertical wall portions without causing buckling occurring in a component shape not having a flange portion. A punch and a pad sandwiching a top sheet portion therebetween in the sheet thickness direction, bending blades for bend-forming the vertical wall portions, and stoppers facing the bending blades in the press direction and constraining end portions of a material to be machined are provided. The punch is supported by a first cushion component elastically expandable and contractible in the press direction. The bending blades each have an upper die component and a lower die component disposed facing each other in the press direction with an interval (D) equal to or larger than a set compression amount and a second cushion component interposed between the upper die component and the lower die component, maintaining the interval (D), and contractible in the press direction at a predetermined pressure or more. The cushion pressure of the second cushion component is lower than the cushion pressure of the first cushion component and has such cushion pressure that the second cushion component does not contract during the bend-forming of the vertical wall portions.