Cryogenic Shielding for WAAM Nozzle Spatter and Weld Pool Cooling
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Solution Overview
Problem
Current wire arc additive manufacturing (WAAM) processes face challenges with spatter buildup in nozzles and incomplete cooling of printed parts, leading to poor deposition quality and mechanical properties due to inadequate shielding and heat management.
Innovation Solution
The implementation of cryogenic shielding using cryogenic sources, such as cryogenic liquids and gases, which expand to provide better gas shielding and rapid cooling of the weld pool and printed parts, preventing spatter attachment to the nozzle and enhancing cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional shielding gas is used in wire arc additive manufacturing, then the arc can be protected from contaminants, but spatter buildup occurs in the nozzle and cooling efficiency is insufficient
Solution Approach 1:
The patent changes the temperature parameter of the shielding gas from ambient to cryogenic levels (below -150°C). This parameter change causes the shielding gas to condense spatter particles through thermal condensation, preventing spatter buildup in the nozzle while maintaining arc shielding effectiveness. The cryogenic temperature transforms the shielding gas from a passive protective medium to an active spatter management system.
Solution Approach 2:
The patent utilizes phase transitions of the shielding gas from gaseous to condensed/liquid state through cryogenic cooling. This phase transition enables the shielding gas to effectively capture and condense spatter particles, preventing them from adhering to the nozzle. The phase change mechanism transforms the shielding process from simple atmospheric exclusion to active particle capture and removal.
2Productivity
If higher deposition rates are used to improve productivity, then manufacturing speed increases, but heat management becomes inadequate leading to poor mechanical properties
Solution Approach 1:
The patent introduces cryogenic temperature parameters to the shielding gas, creating a thermal gradient that actively manages heat in the weld pool and deposited material. This parameter change enables rapid cooling of the deposited layers, controlling microstructure formation and improving mechanical properties even at high deposition rates. The cryogenic shielding gas acts as a heat sink, balancing the thermal input from the arc.
Solution Approach 2:
The patent maintains continuous cryogenic shielding throughout the deposition process, ensuring uninterrupted thermal management. The continuous flow of cryogenic gas provides sustained cooling action, allowing high deposition rates to be maintained without thermal accumulation. This continuous action ensures consistent heat management across all deposited layers.
3Ease of operation
If ambient temperature shielding gas is used, then the system is simple to operate, but rapid cooling of the weld pool and printed parts cannot be achieved
Solution Approach 1:
The patent changes the temperature parameter of the shielding gas to cryogenic levels, fundamentally altering the cooling capability of the system. This parameter change enables rapid cooling of the weld pool and deposited parts, controlling microstructure and improving mechanical properties. The cryogenic temperature parameter transforms the shielding gas from a thermal neutral medium to an active cooling agent.
Solution Approach 2:
The patent replaces traditional mechanical cooling systems (such as water cooling channels or external cooling fixtures) with a gas-based cryogenic shielding system. This substitution eliminates complex mechanical cooling infrastructure while achieving superior cooling effectiveness through the phase change and thermal conductivity properties of cryogenic gases.
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 significantly reduces spatter buildup, improves nozzle cleanliness, and enhances the mechanical properties and accuracy of printed parts by rapid cooling, allowing for higher deposition rates and better heat management during the additive manufacturing process.
Implementation Method 1
the cryogenic source expands in volume when in contact with the nozzle such that the expanded cryogenic source shields the arc and the molten feedstock
Implementation Method 2
cooling the substrate during printing
Implementation Method 3
The expanded cryogenic source solidifies a spatter comprising the molten feedstock
Implementation Method 4
an arc is configured to melt the feedstock at a distal end of the nozzle
Implementation Method 5
an arc is configured to melt the feedstock
Data Source
AI summary
Cryogenic sources can be used for shielding in wire-based additive manufacturing. Cryogenic shielding can provide better shielding during print, as well as more efficient cooling compared to using regular room temperature shielding gas. Cryogenic shielding can extend the nozzle run time by preventing spatter build up in nozzles. Cryogenic sources also can be used for active part cooling and/or active weld puddle cooling.