Dual Plasma Torch Assembly for High-Rate Wire Arc Deposition
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Solution Overview
Problem
Current wire arc additive manufacturing (WAAM) processes face limitations in deposition rate and quality, particularly when dealing with large-scale metal structures, as they often result in lower deposition rates and can be prone to defects due to the physics of the welding process, which restricts the feed rate of the electrode wire and affects the efficiency of material deposition.
Innovation Solution
The implementation of a dual plasma wire arc additive manufacturing system that uses a dual plasma torch assembly with a first channel for creating an electric arc to melt the feedstock wire and a second channel for generating a plasma to shield the wire and substrate, combined with the use of multiple feed wires, including a hot wire and one or more cold wires, to enhance deposition rates and improve material distribution within the weld pool.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional wire arc additive manufacturing is used, then the process is simpler and equipment is less complex, but the deposition rate is lower and productivity is reduced
Solution Approach 1:
The torch assembly is segmented into two separate channels: a first channel for delivering shielding gas and a second channel for generating plasma. This segmentation allows each channel to be optimized for its specific function, enabling higher deposition rates while maintaining manageable complexity through modular design
Solution Approach 2:
A plasma field is introduced as an intermediary between the wire feedstock and the weld pool. This plasma mediator enhances heat transfer efficiency and protects the molten pool from oxidation, enabling faster deposition rates without compromising material quality or increasing operational complexity
2Productivity
If higher wire feed rates are used to increase deposition rate, then productivity improves, but defects increase due to welding physics limitations
Solution Approach 1:
The process parameters are changed by introducing plasma with high energy density, which alters the thermal field distribution in the weld pool. This enables the system to handle higher wire feed rates without creating defects, as the plasma provides more uniform and intense heating that prevents common welding defects
Solution Approach 2:
The shielding gas and plasma are combined in a composite shielding system where the plasma provides both thermal energy and protective atmosphere. This composite approach allows higher deposition rates while maintaining low defect levels through enhanced protection and heat control
3Manufacturing precision
If conventional single plasma or arc shielding is used, then the equipment is simpler, but material distribution in the weld pool is less uniform and quality is reduced
Solution Approach 1:
The torch is divided into two functional channels that work in concert: the first channel provides shielding gas flow while the second channel generates plasma. This segmentation enables independent optimization of each function, resulting in superior grain structure and material distribution without excessive complexity
Solution Approach 2:
The plasma is generated at the specific location where it is most needed - directly at the weld pool interface. This localized quality enhancement ensures optimal heat distribution and material melting characteristics, improving grain structure and overall part quality
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 increases deposition rates, achieving up to 30 pounds per hour with aluminum alloys while maintaining low defect levels, and improves the grain structure and temperature profile of the printed parts, enabling faster production of large-scale metal structures with enhanced quality.
Implementation Method 1
a power source is configured to apply between a feedstock wire moving through the first channel and a substrate; wherein the power source is configured to create an electric arc to melt the feedstock wire
Implementation Method 2
an electrode is configured to apply a signal to the second shielding gas at a distal end of the second channel such that the signal ionizes the second shielding gas to form a plasma to shield the feedstock wire and the substrate
Data Source
AI summary
A device may position a torch assembly relative to a workpiece. A device may initiate a pilot arc between a plasma electrode and a grounded portion of a torch assembly, the grounded portion of the torch assembly grounded using a component with a variable resistance. A device may initiate a wire arc between a first wire element and the workpiece. A device may add material to the workpiece while the torch assembly traverses the workpiece.