Gear-Based Liquefier Assembly for Additive Manufacturing
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Solution Overview
Problem
Existing additive manufacturing systems face challenges in achieving precise control over the flow of molten materials during the extrusion process, leading to inconsistencies and ripples in the deposited layers, particularly due to the reliance on viscosity-pump actions and mechanical limitations.
Innovation Solution
The implementation of a downstream gear assembly within the print head extruder, which includes a pair of engaged gears that rotate to regulate the flow of molten material, providing a controlled and consistent extrusion process by eliminating the need for a moving meniscus and reducing the volume of molten material that needs to be pressurized, thus enhancing transient response and flow control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If viscosity-pump actions are used to control molten material flow, then the extrusion process can be maintained, but flow control precision deteriorates leading to inconsistencies and ripples in deposited layers
Solution Approach 1:
The patent replaces the viscosity-pump mechanical action with a gear-based positive displacement pumping system. The gear assembly with drive gear and idler gear creates controlled cavities that mechanically meter and transport molten material, eliminating reliance on material viscosity for flow control. This mechanical substitution provides precise, consistent flow regulation regardless of material properties, resolving the contradiction between flow control precision and extrusion consistency.
Solution Approach 2:
The patent changes the fundamental parameter of flow control from viscosity-dependent to gear-rotation-dependent. By controlling the rotation speed and timing of the gear assembly, the system achieves precise flow metering. The gear cavity volume and rotation rate become the controlling parameters, enabling accurate flow regulation that is independent of molten material viscosity variations, thereby improving both precision and consistency.
2Speed
If a moving meniscus is used in the extrusion system, then material can be pressurized, but the volume of molten material requiring pressurization increases, slowing transient response
Solution Approach 1:
The patent extracts and eliminates the moving meniscus component from the extrusion system. Instead of relying on a meniscus to seal and pressurize material, the gear assembly uses discrete gear cavities that are sealed by gear teeth engagement. This removal of the meniscus reduces the volume of molten material that must be pressurized at any time, as material is pressurized in small, discrete gear cavity portions rather than in a large continuous volume, thereby speeding up transient response.
Solution Approach 2:
The patent segments the molten material flow into discrete portions contained within gear cavities. Each gear cavity acts as an independent pressurization chamber, allowing material to be pressurized in small, manageable segments rather than as a large continuous volume. This segmentation enables faster pressurization cycles and quicker transient response, as each cavity can be pressurized independently and rapidly by the gear rotation.
3Manufacturing precision
If conventional extrusion methods are used, then 3D parts can be formed, but bead width variations occur, reducing the quality of deposited layers
Solution Approach 1:
The patent incorporates feedback control through the gear assembly's mechanical metering action. The fixed geometry of the gear cavities and their engagement with the casing creates a predetermined, repeatable displacement volume per rotation. This mechanical feedback ensures that the same volume of material is delivered per unit time, maintaining consistent bead width. The system self-regulates flow based on gear rotation rather than requiring complex external feedback controls, preserving ease of operation while achieving precision.
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 solution enables faster and more consistent extrusion with reduced bead width variations, improving the quality of deposited layers by dynamically controlling the flow rates and minimizing thermal expansion, resulting in smoother and more uniform 3D part formation.
Implementation Method 1
a liquefier configured to receive and melt the consumable material fed from the drive mechanism to produce a molten material
Implementation Method 2
a gear assembly including a casing assembly that has an inlet opening configured to operably receive the pressurized molten material from the liquefier, an interior cavity configured to receive the pressurized molten material from the inlet opening, and an outlet opening; a first gear disposed within the interior cavity, and configured to rotate under motorized power, and a second gear engaged with the first gear, and configured to counter rotate with the rotation of the first gear, where the rotations of the first and second gears regulate a flow of the pressurized molten material from the inlet opening to the outlet opening
Data Source
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AI summary
A liquefier assembly (20) for use in an additive manufacturing system (10) to print three-dimensional parts (22), which includes an upstream pressure-generating stage (52) and downstream flow-regulating stage (52). The upstream pressure-generating stage (52) includes a drive mechanism (46), a liquefier configured (52) to melt a consumable material (48) receive from the drive mechanism (46) to produce a molten material in a pressurized state. The downstream flow-regulating stage (52) includes a gear assembly (52) having a casing assembly (64,66,68) and a pair of gears (74,76) disposed within the interior cavity (78,80) and engaged with each other to regulate a flow of the pressurized molten material (48) through the gear assembly (52) for controlled extrusion.