Fibre-Reinforced Additive Manufacturing Printhead for Roving Infiltration
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Solution Overview
Problem
Existing additive manufacturing technologies for fibre-reinforced materials lack flexibility in choosing and combining fibre and matrix materials, result in poor bonding between fibres and matrix, and are limited by small thread sizes leading to high printing times and mechanical instability.
Innovation Solution
A printhead design that infiltrates fibre roving with a molten polymer within an infiltration unit, using deflecting elements to guide the fibre roving transversely to the polymer flow, enhancing penetration and bonding, allowing for thicker fibre bundles and varied matrix materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If small thread sizes of fibres are used, then the fibre reinforcement can be incorporated, but the printing time becomes very high for large objects
Solution Approach 1:
The patent changes the parameter of fibre thread size from small (conventional) to large (thick), and simultaneously changes the matrix material from thermoplastic to thermoset which cures instead of melting. This parameter change allows using thicker fibres that reduce printing time while maintaining fibre reinforcement benefits.
Solution Approach 2:
The patent replaces the melting phase transition of thermoplastics with the curing phase transition of thermoset polymers. The thermoset matrix cures from liquid/resin state to solid, enabling the use of thicker fibres without the melting constraints that limited fibre size in conventional thermoplastic processes.
2Loss of time
If thicker fibres are used, then printing time is reduced, but winding as filament becomes impossible due to high bending stiffness
Solution Approach 1:
The patent changes the physical state of the matrix material from thermoplastic (meltable) to thermoset (curable), and changes the fibre morphology from continuous filament to discontinuous roving. This allows thicker fibres to be used for rapid printing while the thermoset matrix can impregnate the fibre rovings without requiring the fibres to be wound into filaments.
Solution Approach 2:
The patent segments the fibre reinforcement from continuous filaments into discontinuous rovings (bundles of fibres). This segmentation allows thicker fibre structures to be used directly in the printing process without requiring them to be wound into manageable filaments, as the thermoset matrix will impregnate the rovings during printing.
3Ease of manufacture
If a thermoplastic matrix material is used, then the material can be processed, but the mechanical properties fluctuate strongly due to moisture content
Solution Approach 1:
The patent changes the matrix material from thermoplastic to thermoset polymer. Thermoset polymers do not suffer from moisture-induced property fluctuations like thermoplastics, providing stable mechanical properties. The thermoset matrix still processes easily through standard injection molding techniques while eliminating the moisture sensitivity problem.
4Device complexity
If the matrix material only wraps or coats the fibres, then the process is simple, but forces cannot be transmitted between fibres or between fibre and matrix
Solution Approach 1:
The patent changes the matrix material from thermoplastic to thermoset, and changes the fibre form from continuous to discontinuous roving. The thermoset matrix is then injected under pressure to fully impregnate the fibre rovings, creating strong fibre-matrix bonding that enables force transmission. This remains a relatively simple injection molding process while achieving superior composite strength.
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
Enables flexible production of fibre-reinforced materials with improved mechanical properties by ensuring thorough infiltration and bonding between fibres and matrix, reducing printing time and material limitations.
Implementation Method 1
a heating element for the partial melting of the polymer within the infiltration unit
Implementation Method 2
the fibre roving can be guided within the channel, by means of deflection around the deflection element, area by area, transversely to the polymer flow direction
Data Source
AI summary
In a first aspect, the invention refers to a printhead for the additive manufacturing of a fibre reinforced material, comprising a fibre reinforcement in a polymer matrix, comprising an infiltration unit for mixing and/or infiltrating a fibre roving with a molten polymer; at least one feeder for a polymer and/or a fibre roving to the infiltration unit; a heating element, at least for partially melting the polymer within the infiltration unit; at least one deflecting element within the infiltration unit and an outlet for the resulting fibre reinforced material from the infiltration unit, wherein the molten polymer can be guided within the infiltration unit with a polymer flow direction, from the feeder to the outlet, along a channel between the feeder and the outlet, and the fibre roving can be guided within the channel, by means of deflection, around the deflecting element, area by area, transversely to the polymer flow direction, from the feeder to the outlet.In another aspect, the invention refers to the use of a printhead for additive manufacturing, as well as to a process for additive manufacturing, and to a fibre reinforced material produced by the printhead.