Extrusion-Based Additive Manufacturing Flow Control
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Solution Overview
Problem
Extrusion-based additive manufacturing systems face challenges in controlling the flow rate of liquid matrix material independently of the fibre flow, leading to potential distortions and pressure issues during the deposition of layers.
Innovation Solution
The method involves melting thermoplastic matrix material and feeding it into a chamber with a fibre, where the fibre and matrix material are coated and extruded simultaneously, allowing for controlled pressure and flow rates, with the fibre moving at the same velocity in and out of the chamber, and the matrix material being extruded at a higher velocity to achieve consistent layer deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the fibre moves at the same velocity in and out of the chamber, then the coating process is stable and consistent, but the liquid matrix material cannot be pressurized independently to control flow rate
Solution Approach 1:
The system segments the material flow control into two independent channels: one for the fibre (moving at constant velocity through the chamber) and one for the liquid matrix material (with variable flow rate controlled by a separate pump). This allows the coating process to remain stable while enabling independent pressure and flow rate adjustment of the matrix material.
Solution Approach 2:
The liquid matrix material flow rate is made dynamic and adjustable through a pump system, while the fibre movement remains static at constant velocity. This dynamic adjustment capability allows the matrix material flow to be optimized independently for different coating requirements without affecting fibre positioning or coating consistency.
2Productivity
If the liquid matrix material flow rate is increased to improve layer deposition speed, then productivity increases, but pressure control becomes difficult leading to distortions
Solution Approach 1:
The system incorporates feedback control through a pump that adjusts the liquid matrix material flow rate based on pressure sensors monitoring the chamber pressure. This feedback mechanism allows the flow rate to be increased for higher productivity while automatically maintaining pressure within acceptable ranges to prevent distortions.
Solution Approach 2:
The system independently adjusts the flow rate parameter of the liquid matrix material through the pump while maintaining the fibre movement parameter at constant velocity. This parameter separation allows optimization of deposition speed without compromising pressure control, as each parameter can be tuned independently.
3Manufacturing precision
If the matrix material is extruded at higher velocity than the fibre, then coating application is improved, but the coating may not solidify properly before the fibre moves out of the chamber
Solution Approach 1:
The system performs preliminary heating of the liquid matrix material in the chamber before it contacts the fibre, ensuring it is in the optimal state for coating. The material is heated to a temperature that facilitates proper coating application and subsequent solidification, preparing it in advance for the coating process.
Solution Approach 2:
The system utilizes phase transitions of the matrix material, transitioning it from solid to liquid in the heating zone, then applying it as a liquid coating to the fibre, and finally allowing it to solidify upon contact with the cooler fibre surface. This controlled phase transition enables proper coating application and solidification.
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 enables precise control over the pressure and flow rates, reducing distortions and enhancing the bonding between layers, resulting in improved structural integrity and reduced defects in the manufactured object.
Implementation Method 1
melting thermoplastic matrix material to transform it into liquid matrix material
Implementation Method 2
extruding a coated fibre from an extrusion outlet of the chamber onto a substrate, the coated fibre comprising the fibre with a coating of the liquid matrix material
Implementation Method 3
the coating fuses with the previously extruded coated fibre and solidifies after it has fused with the previously extruded coated fibre
Data Source
AI summary
A method of manufacturing an object. A thermoplastic matrix material is melted to transform it into liquid matrix material. The liquid matrix material is fed into a chamber via one or more matrix inlets. A fiber is also fed into the chamber via a fiber inlet. The fiber in the chamber is contacted by the liquid matrix material. A coated fiber is extruded from an extrusion outlet of the chamber onto a substrate, the coated fiber comprising the fiber with a coating of the liquid matrix material, the substrate comprising a previously extruded coated fiber. The fiber moves in and out of the chamber at the same velocity relative to the chamber. The coating fuses with the previously extruded coated fiber and solidifies after it has fused with the previously extruded coated fiber. Relative movement is generated between the extrusion outlet and the substrate as the coated fiber is extruded from the extrusion outlet.