Continuous Fiber 3D Printing Paths for Stable Layer Adhesion

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Solution Overview

Problem

Existing filaments reinforced with continuous fibers exhibit unstable fiber spreading and decreased fusibility when extruded in 3D printing, leading to reduced mechanical strength between lines and layers, particularly with high twist numbers.

Innovation Solution

The method involves extruding a continuous fiber reinforced filament with a thermoplastic resin, twisting the fibers 20 to 100 times per meter, and depositing curved or bent shapes by alternating the extrusion direction based on the twist type (Z-twist or S-twist) to maintain fiber spreading and strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the number of twists applied to the reinforcing fibers is increased to improve impact strength, then the filament flexibility and handleability improve, but the spread width of the reinforcing fibers decreases or becomes unstable during extrusion

Engineering Contradiction:
Improveimpact strengthVSAvoidspread width of reinforcing fibers
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The patent optimizes the twist number parameter to a specific range (10-100 twists/m) to balance fiber spreading stability with impact strength. This parameter change resolves the contradiction by finding the optimal value that prevents excessive fiber twisting while maintaining filament flexibility and handleability.

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If the number of twists applied to the reinforcing fibers is large, then the filament has increased flexibility, but the fusibility of the depositing material decreases between adjacent depositing paths

Engineering Contradiction:
ImproveflexibilityVSAvoidfusibility between depositing paths
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent sets the twist number within the optimal range of 10-100 twists/m to maintain filament flexibility while preventing excessive fiber entanglement that would reduce fusibility between adjacent depositing paths.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If the number of twists applied to the reinforcing fibers is increased, then the filament handleability improves, but voids are more likely to be generated during deposition

Engineering Contradiction:
ImprovehandleabilityVSAvoidvoid formation
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The patent optimizes the twist number to 10-100 twists/m to balance filament handleability with proper fiber spreading during deposition, preventing void formation while maintaining ease of operation.

Inventive Principle:
Principle #35Parameter changes

4Ease of operation

If the number of twists applied to the reinforcing fibers is increased, then the filament flexibility improves, but the mechanical strength between lines and between layers decreases

Engineering Contradiction:
ImproveflexibilityVSAvoidmechanical strength between lines and layers
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The patent determines the optimal twist number range of 10-100 twists/m to maintain filament flexibility while ensuring adequate mechanical strength between lines and layers through proper fiber spreading during extrusion.

Inventive Principle:
Principle #35Parameter changes

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 maintains mechanical strength between lines and layers without decreasing fiber spreading, enhancing the adhesion and stability of deposited objects.

Implementation Method 1

heating and fusing a linear continuous fiber reinforced filament

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 2

heating and fusing a linear continuous fiber reinforced filament

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 3

the continuous fiber of the fiber bundle is twisted 20 times/m or more and 100 times/m or less about an axis of the continuous fiber reinforced filament

Methodology Applied
Scientific EffectTwisting:

Implementation Method 4

extruding a depositing material obtained by heating and fusing a linear continuous fiber reinforced filament from a nozzle along a depositing path

Methodology Applied
Scientific EffectExtrusion: Extrusion

Data Source

PatentEP4717441A1Additive manufacturing method, additive manufacturing equipment, and program
Publication Date: 2026.04.01 KOBE STEEL LTD
  • EP4717441A1 patent drawingFigure 1
  • EP4717441A1 patent drawingFigure 2A
  • EP4717441A1 patent drawingFigure 2B

AI summary

A continuous fiber reinforced resin filament includes a base material containing a thermoplastic resin and at least one fiber bundle impregnated with the base material and containing a continuous fiber extending in an axial direction. The continuous fiber of the fiber bundle is twisted 20 times/m to 100 times/m about an axis of the continuous fiber reinforced resin filament. A curved shape or a bent shape is deposited by setting the depositing path on the depositing surface to a path for extruding the depositing material while curving or bending rightward toward a front side in a depositing direction when the fiber bundle is Z-twisted, and to a path for extruding the depositing material while curving or bending leftward toward the front side in the depositing direction when the fiber bundle is S-twisted.