Coarse-Fine Print Assembly for Additive Manufacturing
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Solution Overview
Problem
Current extrusion-based additive manufacturing systems face limitations in achieving high-resolution parts and fast printing speeds due to acceleration and deceleration constraints imposed by the fundamental resonance frequencies of print head gantries, particularly when negotiating tortuous tool paths.
Innovation Solution
The implementation of a print assembly with multiple robotic positioners providing coarse-fine position control and multiple-stage liquefier assemblies, allowing for high positional accuracy and fast extrusion control, which includes a coarse positioner and fine positioners with differing resonance frequencies and a liquefier assembly with upstream and downstream stages connected by a conduit, enabling quick accelerations and decelerations without inducing position errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a single robotic positioner is used to move the print head, then the device complexity is reduced, but the printing speed and acceleration capability are limited by the fundamental resonance frequency
Solution Approach 1:
The single robotic positioner is segmented into two independent positioners: a coarse positioner for large-range movements and a fine positioner for high-precision, high-speed adjustments. This segmentation allows each positioner to operate within its optimal performance range, enabling faster printing speeds without exceeding the fundamental resonance frequency limits of individual positioners.
Solution Approach 2:
The control system adds a new dimension of control by coordinating two positioners operating at different scales. The coarse positioner handles the primary movement dimension while the fine positioner handles the correction dimension, effectively creating a hierarchical control structure that overcomes the speed limitations of a single positioner.
2Productivity
If the print head accelerates and decelerates quickly to increase printing speed, then productivity improves, but position errors occur due to resonance effects
Solution Approach 1:
The coarse positioner performs preliminary positioning actions to reach the general target area, allowing the fine positioner to make final precision adjustments. This preliminary action separates the high-speed traversal from the high-precision deposition, enabling quick accelerations without compromising accuracy.
Solution Approach 2:
The fine positioner acts as an intermediary between the coarse positioner and the print head. It mediates the transition from coarse, fast movements to fine, precise movements, filtering out resonance effects and ensuring accurate deposition even when the coarse positioner operates at high speeds.
3Manufacturing precision
If the print head moves slowly to maintain position accuracy, then manufacturing precision is maintained, but printing speed and productivity decrease
Solution Approach 1:
The system dynamically switches between coarse and fine positioner control based on the operational requirements. During traversal phases, the coarse positioner operates at high speed with relaxed precision requirements, while during deposition phases, the fine positioner takes over to ensure high precision. This dynamic allocation optimizes both speed and accuracy.
4Manufacturing precision
If a multi-stage liquefier assembly is implemented to improve extrusion control, then deposition accuracy improves, but device complexity increases
Solution Approach 1:
The liquefier assembly is segmented into multiple stages, each responsible for a specific function in the material delivery chain. This segmentation allows independent optimization of each stage and enables precise control of extrusion parameters without requiring complete redesign of the entire system.
Solution Approach 2:
The multi-stage liquefier assembly replaces simple mechanical extrusion with a more sophisticated system that incorporates controlled material flow management. This substitution enables superior extrusion control through coordinated operation of multiple stages rather than relying solely on mechanical pressure.
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 increased printing speeds while maintaining deposition accuracy, even on complex tool paths with sinusoidal geometries and sharp corners, by supplementing the slower accelerations of coarse positioners with faster decelerations of fine positioners and utilizing the liquefier assembly to manage extrudate flow effectively.
Implementation Method 1
a liquefier assembly configured to melt and extrude a consumable material
Data Source
AI summary
A print assembly 18 for use in an additive manufacturing system 10 to print three-dimensional parts 12, which includes a coarse positioner 40, a fine positioner 42, and a liquefier assembly 20, where a portion of the liquefier assembly 20 is operably mounted to the fine positioner 42 such that the fine positioner 42 is configured to move the portion of the liquefier assembly 20 relative to the coarse positioner 40.