Segmented Molding Core for Easy Removal From Hat-Section Stringers

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Solution Overview

Problem

Existing cores made of hard materials used in integrally molding fiber-reinforced resin structures are difficult to remove after forming due to partial deformation, which can cause the dies to collapse.

Innovation Solution

A core configuration comprising separable dies, including a first, second, and third die, where the third die is designed to be easily pulled out, allowing the first and second dies to collapse, facilitating easy removal without deformation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a core made of hard material is used to prevent partial deformation of the skin surface, then the surface quality is improved, but the core becomes difficult to pull out after forming

Engineering Contradiction:
Improvesurface qualityVSAvoidcore removal
Core Design Contradiction:
Manufacturing precisionVSEase of operation

Solution Approach 1:

The core is divided into multiple separate dies (first die, second die, and third die) that can be independently removed. The third die is specifically designed to be pulled out first, which causes the first and second dies to collapse and facilitates their easy removal, thereby solving the core removal difficulty while maintaining surface quality

Inventive Principle:
Principle #1Segmentation

2Force

If large force is applied to the outer surface of the skin during integrally molding, then the forming pressure is improved, but the core surface that contacts the skin may become partially deformed

Engineering Contradiction:
Improveforming pressureVSAvoidcore surface deformation
Core Design Contradiction:
ForceVSManufacturing precision

Solution Approach 1:

The core is segmented into multiple dies that can independently bear and distribute the forming pressure. This segmentation allows the core to withstand large forming forces without experiencing localized partial deformation that would occur in a single-piece core, thereby maintaining surface quality under high pressure

Inventive Principle:
Principle #1Segmentation

3Strength

If the core is made of hard material to maintain structural integrity, then the core strength is improved, but the flexibility for easy removal is reduced

Engineering Contradiction:
Improvecore strengthVSAvoidcore removal
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The hard core is divided into multiple separate dies that can be independently removed. The third die is designed to be pulled out first, which causes the first and second dies to collapse due to their interconnected structure, enabling easy removal of all dies while maintaining the overall structural integrity and strength of the core during the forming process

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The core transitions from a static, monolithic structure to a dynamic, separable structure. The multiple dies can move independently during removal, with the third die being pulled out first to trigger the collapse and easy removal of the first and second dies, thereby enabling easy removal while maintaining strength during forming

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP4137290B1Core and method for molding structure
Publication Date: 2025.12.10 KAWASAKI JUKOGYO KK
  • EP4137290B1 patent drawingFigure 1
  • EP4137290B1 patent drawingFigure 2A~2G
  • EP4137290B1 patent drawingFigure 3A~3C

AI summary

A core according to one aspect of the present disclosure is a core that is inserted into a space between a skin and a stringer in a step of integrally molding the skin and the stringer, the skin including fiber-reinforced resin, the stringer having a hat-shaped section that is open toward the skin. The core includes: a first die that extends along a longitudinal direction of the stringer and contacts the skin; a second die that extends along the longitudinal direction of the stringer, is adjacent to the first die, and contacts the skin; and a third die that extends along the longitudinal direction of the stringer, is located at an opposite side of the skin across the first die and the second die, and contacts both the first die and the second die.