Composite Wire Sheath Forming for Mold-Free Helical Springs

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Solution Overview

Problem

Existing methods for producing complex composite structures, such as molded or extruded bodies for aerospace and automotive applications, are costly and limit large-scale production due to high tooling costs and non-removable components.

Innovation Solution

A method involving a yarn blank of fibers and unpolymerized resin, coated with a molten eutectic sheath, is translated and rotated to achieve the desired shape, with controlled cooling and polymerization, allowing for the production of complex shapes like helical springs without the need for expensive molds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If traditional molding processes with drawers and complex elements are used, then demolding capability is improved, but production cost increases significantly

Engineering Contradiction:
Improvedemolding capabilityVSAvoidmold complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The invention extracts the demolding function from complex mold drawers and mechanisms, replacing it with a simple core that is melted away. The core serves only as a temporary support during manufacturing, then is removed by melting, eliminating the need for complex demolding mechanisms.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the physical state parameter of the core material from solid to liquid through controlled heating. The core is initially solid to provide structural support during manufacturing, then transformed to liquid state through melting to enable easy removal, thus simplifying the demolding process.

Inventive Principle:
Principle #35Parameter changes

2Strength

If traditional molding processes are used, then structural integrity is maintained, but large-scale production capability is limited

Engineering Contradiction:
Improvestructural integrityVSAvoidproduction scalability
Core Design Contradiction:
StrengthVSProductivity

Solution Approach 1:

The invention uses a disposable core made from inexpensive eutectic material that is melted and discarded after serving its temporary purpose. This allows for rapid production cycles and large-scale manufacturing without the need for expensive, complex molds, thereby improving productivity and scalability.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Device complexity

If lost core casting with eutectic material is used, then production cost is reduced, but tooling cost increases significantly

Engineering Contradiction:
Improveprocess simplicityVSAvoidtooling cost
Core Design Contradiction:
Device complexityVSEase of manufacture

Solution Approach 1:

Instead of creating a complex mold and removing the part, the invention inverts the approach by creating a simple core and removing it through melting. This reversal of the traditional manufacturing logic eliminates the need for expensive mold tooling while maintaining process simplicity.

Inventive Principle:
Principle #13The other way round (Inversion)

4Ease of operation

If complex molds are used for demolding, then part removal is enabled, but production time increases

Engineering Contradiction:
Improvepart removalVSAvoidproduction time
Core Design Contradiction:
Ease of operationVSLoss of time

Solution Approach 1:

The invention utilizes the phase transition of the core material from solid to liquid through melting. This phase change enables rapid and complete removal of the core from the composite structure, significantly reducing the time required for part removal compared to mechanical demolding operations.

Inventive Principle:
Principle #36Phase transitions

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 method reduces production costs and enables the creation of complex shapes like helical springs efficiently, overcoming the limitations of traditional methods by allowing for removability and scalability.

Implementation Method 1

a eutectic sheath 20 of a material whose melting temperature is lower than the glass transition temperature of the resin 14 and the softening temperature of the fibers 12

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 2

after the body molded onto the core has stiffened

Methodology Applied
Scientific EffectPolymerization: Photopolymerisation

Data Source

PatentEP2861412B1Method for obtaining a body having a given shape from a wire or the like
Publication Date: 2021.07.28 S ARA COMPOSITE
  • EP2861412B1 patent drawingFigure 1
  • EP2861412B1 patent drawingFigure 2~3

AI summary

The present invention relates to the methods for obtaining a body (Cp), which is required to have a given shape, from a wire or the like. The method consists of: producing (Ph1) a blank (10) of the wire in the form of a mixture of fibres (12) and polymerisable resin (14); translating (Ph2) the blank (10) in a given direction and, during the translation (Tr) of the blank (10), producing a sheath (20) around the blank (10) using a molten sheathing material (22), the melting point of which is lower than the glass-transition temperature of the resin (14) and the melting point of the fibres (12); simultaneously cooling (Ph3) the unit in order to achieve the relative solidification of the sheath (20) and shaping the unit into the given shape; maintaining (Ph4) the temperature of the unit for a predetermined amount of time in order to achieve the nearly complete polymerisation of the resin (14); heating (Ph5) the unit to a temperature that is lower than the glass-transition temperature of the resin (14) but higher than the melting point of the sheathing material, until the latter has melted; and recovering (Ph6) the formed body (Cp). The invention can be advantageously used to manufacture helical or pseudo-helical springs.