DED Nozzle Cover Gas Flow for Low-Oxygen Powder Bed AM
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Solution Overview
Problem
In Additive Manufacturing (AM) methods like Direct Energy Deposition (DED) and Powder Bed Fusion (PBF), maintaining a low oxygen concentration at the fabrication position is challenging due to the flow rate of purge gases, which can either disturb the powder flow or fail to adequately eliminate oxygen, affecting the stability and accuracy of the fabrication process.
Innovation Solution
An AM apparatus with a DED nozzle featuring a cover that surrounds the laser and powder ports, incorporating a gas supply passage to guide inert gas towards the nozzle, ensuring a controlled flow that reduces oxygen concentration without disrupting the powder flow, and includes a lattice structure layer in the gas supply passage to diffuse the gas and maintain a stable environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a large flow rate of purge gas is used to decrease oxygen concentration in the fabrication position, then the oxygen elimination is improved, but the powder flow and carrier gas flow are disturbed causing unstable fabrication
Solution Approach 1:
The gas supply system is segmented into multiple independent gas supply ports around the DED nozzle, allowing different gas flows to be controlled separately. This enables the purge gas to be supplied at optimized locations without interfering with the powder flow path, thus decreasing oxygen concentration while maintaining fabrication stability.
Solution Approach 2:
A cover structure is introduced as an intermediary component that surrounds the DED nozzle and creates a controlled gas environment. The cover with its multiple gas supply ports acts as a mediator between the purge gas source and the fabrication position, directing gas flow to eliminate oxygen while protecting the powder flow from disruption.
2Reliability
If a small flow rate of purge gas is used to avoid disturbing powder flow, then the fabrication stability is improved, but the oxygen elimination becomes insufficient
Solution Approach 1:
By segmenting the gas supply into multiple ports positioned at different locations around the nozzle, the system can maintain low overall gas flow rates while still achieving effective oxygen elimination at the fabrication position. Each port supplies a controlled amount of gas that contributes to the overall purge effect without causing turbulence.
Solution Approach 2:
The gas supply is optimized for local conditions at each port location. The cover structure enables different regions around the nozzle to have tailored gas flow characteristics, providing sufficient oxygen elimination at the fabrication position while maintaining stable powder flow in the material supply region.
3Productivity
If a DED nozzle supplies powder and gas simultaneously during fabrication, then the material supply is improved, but the gas flow blows the pre-bedded metallic powder away making fabrication difficult
Solution Approach 1:
The gas supply system is segmented into multiple ports that are strategically positioned to differentiate between the powder supply function and the purge function. This segmentation allows the carrier gas to transport powder effectively while the purge gas from separate ports eliminates oxygen without interfering with the pre-bedded powder.
Solution Approach 2:
The cover structure serves as an intermediary that separates the functions of powder supply and oxygen elimination. It provides a controlled environment where powder can be supplied through the DED nozzle while simultaneously managing the gas flow to protect pre-bedded powder from being blown away.
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 configuration effectively decreases oxygen levels at the fabrication site, stabilizes the powder flow, and enhances the accuracy and reliability of the AM process by preventing oxidation and ensuring proper powder distribution.
Implementation Method 1
a gas supply passage for supplying a gas inside the cover, and the gas supply passage is configured to be oriented so as to guide the gas toward the DED nozzle main body
Implementation Method 2
the gas supply passage including a lattice structure layer
Implementation Method 3
a cover configured to surround a peripheral area of the laser port and the powder port of the DED nozzle
Implementation Method 4
melts the metallic material together with a base material using an appropriate heat source
Implementation Method 5
melts and solidifies or sinters the metallic powder to fabricate each layer of a three-dimensional object
Implementation Method 6
the vicinity of a fabrication position is sometimes purged with an inert gas in order to decrease an oxygen concentration in the fabrication position
Data Source
AI summary
Provided is a technique for fabricating a powder material bedded in advance using a DED nozzle. According to one embodiment, there is provided an AM apparatus for manufacturing a fabricated object. The AM apparatus includes a DED nozzle. The DED nozzle includes: a DED nozzle main body; a laser port disposed at a distal end of the DED nozzle main body and for emitting a laser beam, and a laser passage configured to communicate with the laser port and for allowing the laser beam to pass through the DED nozzle main body; and a powder port disposed at the distal end of the DED nozzle main body and for emitting a powder material, and a powder passage configured to communicate with the powder port and for allowing the powder material to pass through the DED nozzle main body. The AM apparatus further includes a cover configured to surround a peripheral area of the laser port and the powder port of the DED nozzle. The cover is configured to have an opened downstream side in an emission direction of the laser beam. The cover includes a gas supply passage for supplying a gas inside the cover. The gas supply passage is configured to be oriented so as to guide the gas toward the DED nozzle main body.