Fiber-Reinforced Resin Hinge Structure for Stable Fold Lines

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Solution Overview

Problem

Resin molded bodies containing inorganic fiber form meandering folded lines at the hinge portion, deteriorating the external appearance when bent.

Innovation Solution

A resin molded body with a hinge portion comprising thin and thick portions, where the thick portion is sandwiched by the thin portions, forming a structured body with a first and second main body portion that are rotatable, and an outer surface material is integrally molded with the resin body.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the resin molded body contains inorganic fiber, then the strength and rigidity are improved, but the folded line meanders when bent at the hinge portion, deteriorating the external appearance

Engineering Contradiction:
Improvestrength and rigidityVSAvoidexternal appearance
Core Design Contradiction:
StrengthVSShape

Solution Approach 1:

The hinge portion is segmented into three distinct regions: a first thin portion, a thick portion, and a second thin portion. This segmentation allows the thin portions to form the folded line while the thick portion provides structural support with inorganic fibers, preventing meander of the folded line while maintaining strength and rigidity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the hinge portion have different thicknesses and fiber distributions. The thin portions have lower fiber concentration allowing flexible bending, while the thick portion has higher fiber concentration providing structural support. This local differentiation resolves the contradiction between flexibility for bending and rigidity from inorganic fibers.

Inventive Principle:
Principle #3Local quality

2Ease of operation

If the hinge portion is made thin to facilitate bending, then the ease of operation is improved, but the structural integrity deteriorates

Engineering Contradiction:
Improveease of bendingVSAvoidstructural integrity
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The hinge is divided into thin portions for bending and a thick portion for structural support. The thin portions (first and second thin portions) facilitate easy bending operations, while the thick portion maintains structural integrity through increased thickness and higher inorganic fiber concentration.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The hinge portion merges two contradictory requirements by combining thin regions (for flexibility) and a thick region (for strength) into a single integrated structure. The thick portion acts as a reinforcing element embedded within the hinge, providing structural integrity without hindering the bending capability of the thin portions.

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

The meandering of the folded line is suppressed, preventing deterioration of the external appearance, and the structure maintains structural integrity and aesthetic appeal.

Implementation Method 1

a resin molded body (resin panel for example) which can be used as a bath lid or as a floor board installed in a luggage compartment of a vehicle

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 2

When the resin molded body of JP 2013-103422 A is bent at its hinge portion, a folded line is formed at the hinge portion

Methodology Applied
Scientific EffectDeformation: Deformation

Data Source

PatentEP3747624B1Method for producing structure
Publication Date: 2025.08.06 KYORAKU CO LTD
  • EP3747624B1 patent drawingFigure 1
  • EP3747624B1 patent drawingFigure 2
  • EP3747624B1 patent drawingFigure 3

AI summary

A structure body having a resin molded body which can suppress deterioration of external appearance due to meander of the folded line formed in the hinge portion even when the resin constituting the resin molded body contains an inorganic fiber. The structure body has a resin molded body and the resin molded body includes: a first main body portion and a second main body portion; and a hinge portion; wherein the first main body portion and the second main body portion are connected at the hinge portion with each other so as to be rotatable with respect to each other; the hinge portion comprises a first thin portion, a second thin portion, and a thick portion; the thick portion is a portion being larger in thickness than the first thin portion and the second thin portion; the first thin portion, the second thin portion, and the thick portion elongate in a longitudinal direction of the hinge portion; and the thick portion is sandwiched by the first thin portion and the second thin portion in a width direction of the hinge portion.