Dynamic Post Metering Volume for Additive Fabrication Pump
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Solution Overview
Problem
Additive fabrication technologies, such as photopolymer extrusion, face challenges with extruder start and stop lag times due to pressure buildup in the post metering volume, leading to unwanted emission of source material from the orifice, especially with highly compressible materials and larger post metering volumes.
Innovation Solution
Dynamic adjustment of the post metering volume by using a moveable element or stator within the chamber to increase or decrease the pressure of the source material, either by displacing a moveable element along a channel or by the motion of a stator within the chamber, allowing for precise control of material extrusion and cessation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the post metering volume is increased to accommodate highly compressible materials, then the material can be more easily pumped and controlled, but extrusion lag time increases and unwanted emission occurs due to pressure buildup
Solution Approach 1:
The patent applies the dynamics principle by making the post metering volume dynamically adjustable rather than fixed. A moveable element is introduced that can shift position to change the volume of the post metering chamber. During pumping, the volume is increased to accommodate compressible materials; during extrusion, the volume is decreased to reduce pressure buildup and eliminate lag time. This dynamic adjustment resolves the contradiction between handling compressible materials and preventing extrusion delays.
2Productivity
If the post metering volume is increased to facilitate material pumping, then material flow is improved, but unwanted emission of source material occurs from the orifice due to pressure buildup
Solution Approach 1:
The moveable element dynamically adjusts the post metering volume to resolve the contradiction between maintaining high material flow and preventing unwanted emission. During the pumping phase, the expanded volume facilitates efficient material transport. During the extrusion phase, the reduced volume prevents pressure buildup that would cause unwanted emission from the orifice, thus eliminating the harmful effect while preserving productivity.
3Device complexity
If a fixed post metering volume is used, then the device structure is simpler, but precise control of material extrusion and cessation is difficult
Solution Approach 1:
The patent introduces a moveable element that can be positioned at different locations within the chamber to dynamically adjust the post metering volume. This dynamic configuration allows precise control over material extrusion and cessation by optimizing the volume for each operational phase, achieving high manufacturing precision while accepting moderate increases in device complexity.
4Quantity of substance
If the post metering volume is larger, then more material can be stored for continuous extrusion, but extrusion lag time increases when starting and stopping
Solution Approach 1:
The moveable element enables dynamic adjustment of the post metering volume to resolve the contradiction between storing sufficient material and minimizing lag time. During continuous extrusion, the volume is maintained to provide adequate material supply. When starting or stopping extrusion, the volume is reduced to minimize the amount of pressurized material, thereby reducing the lag time required to start or cease flow.
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 minimizes or eliminates extrusion lag times and prevents unwanted emission of source material, enabling more precise control over material deposition and reducing waste in additive fabrication processes.
Implementation Method 1
a first actuator configured to drive the source material through the inlet into the chamber and out through the orifice
Implementation Method 2
operating a second actuator to displace a moveable element along a channel coupled to the chamber, thereby decreasing pressure of source material within the chamber
Implementation Method 3
a pump actuator arranged at least partially within the stator and configured to drive the source material through the chamber and out of the orifice
Implementation Method 4
operating the pump actuator in a second direction, different from the first direction, thereby causing a stator arranged at least partially within the chamber to move within the chamber and thereby decrease pressure of source material within the chamber
Data Source
AI summary
Techniques to allow an additive fabrication device to dynamically adjust the size of a post metering volume for adjusting pressure of source material in the volume. These techniques may allow for greater control of material extrusion through an orifice and thereby mitigate or avoid issues of lag time between starting and/or stopping extrusion and/or in which there is unwanted emission of source material through the orifice. In some cases, techniques for adjusting the size of the post metering volume may include operating an actuator arranged in a channel that is coupled to the post metering volume. In some cases, techniques for adjusting the size of the post metering volume may include having a stator that is at least partially arranged within a chamber that defines the post metering volume and is free to move within the chamber.