Rotating Doser Powder Delivery for Additive Manufacturing
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Solution Overview
Problem
Conventional additive fabrication systems, such as Selective Laser Sintering (SLS), face challenges in accurately and consistently delivering powders with low flowability or inconsistent flow properties to the build area, often resulting in uneven deposition and waste due to reliance on complex closed-loop control systems or overflow bins.
Innovation Solution
A powder delivery apparatus comprising a hopper, a trough, and a doser with a cylindrical barrel that rotates to move powder between the hopper and the trough, allowing for precise control of powder delivery without relying on powder flow properties, ensuring consistent powder levels and minimizing waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional powder delivery systems are used, then powder can be delivered to the build area, but the delivery is inaccurate and inconsistent for powders with low or inconsistent flow properties
Solution Approach 1:
The patent replaces gravity-based mechanical powder flow systems with a volumetric dosing system that uses a rotating doser with precisely defined cavities. The doser mechanically measures and transfers specific volumes of powder from the hopper to the build area, eliminating reliance on powder flow properties while maintaining delivery accuracy and consistency.
2Manufacturing precision
If complex closed-loop control systems are used to improve powder delivery accuracy, then delivery precision improves, but system complexity increases
Solution Approach 1:
The volumetric doser is designed with fixed cavity volumes that inherently control the amount of powder transferred. The system is self-regulating through its mechanical design rather than requiring external sensors, controllers, or feedback loops to maintain powder deposition uniformity, thereby achieving precision without complexity.
Solution Approach 2:
The doser cavities are pre-configured with specific volumes designed to deliver the exact amount of powder needed for each layer. This preliminary design of the dosing geometry eliminates the need for real-time control adjustments, simplifying the system while ensuring consistent powder delivery.
3Quantity of substance
If overflow bins are used to manage powder, then powder supply is maintained, but powder waste increases
Solution Approach 1:
The system incorporates a flipper mechanism that monitors powder levels in the hopper and automatically triggers refilling when powder reaches a predetermined low level. This feedback control ensures continuous powder supply to the doser while preventing overflow and minimizing waste by maintaining optimal powder levels in the hopper.
4Speed
If powder is stored in proximity to the build area, then delivery speed improves, but indirect heating occurs that affects powder flowability
Solution Approach 1:
The system separates the powder storage function (hopper) from the build area, positioning the hopper at a distance that isolates it from heat sources. The volumetric doser acts as an intermediary that quickly transfers powder over the distance, maintaining both thermal isolation to preserve flowability and efficient delivery speed through the direct volumetric transfer mechanism.
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 consistent and accurate delivery of powder to the build area, reducing waste and eliminating the need for complex control systems, while maintaining powder quality by minimizing indirect heating and maintaining flowability, thus improving the efficiency of the additive fabrication process.
Implementation Method 1
a doser (320) arranged within the hopper (310) and configured to rotate about an axis such that the recess (322) may be moved into and out of the trough (330) and the hopper (310) by rotating the doser (320) about the axis
Data Source
Figure 1
Figure 2A~2C
Figure 3
AI summary
Techniques are described for consistently moving powder from a hopper (510) into a trough for subsequent delivery into a build area of an additive fabrication system. A powder delivery apparatus (500) may comprise a hopper (510), a trough, and a doser (520). The doser (520) may be configured to rotate about an axis and may include a recess (522, 523) that, when the doser (520) is rotated about the axis, travels into and out of the hopper and into and out of the trough. As a result, when powder is present in the hopper (510), the recess (522, 523) may carry powder from the hopper (510) to the trough when the doser rotates. The trough and doser (520) may be configured so that when the trough contains the desired amount of powder for recoating, the doser does not transfer additional material from the hopper (510) into the trough. As a result, the amount of powder in the trough may be self-regulating.