3D Metal Part Welding Deposition With Local Inert Gas Shielding
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Solution Overview
Problem
Conventional methods for manufacturing metallic parts, such as casting, forging, and machining, result in high material wastage and long delivery times, while additive manufacturing is limited to small parts and low-volume production due to restrictions in size and ambient atmosphere exposure.
Innovation Solution
A method and apparatus for solid freeform fabrication of weldable metallic parts using computer-generated models, where layers are formed with directional weld-bead geometry data, and a welding control system with inert gas shielding and induction heating/cooling, allowing unrestricted size and ambient atmosphere operation, enabling efficient deposition of weldable metals like carbon manganese, aluminum, and titanium alloys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If additive manufacturing is used to manufacture metallic parts, then material wastage is reduced and production time is decreased, but the method is restricted to small parts and low-volume production due to size limitations and enclosed chamber requirements
Solution Approach 1:
The build space is segmented into multiple zones with different atmospheric conditions. The weld zone has controlled atmosphere (inert gas shielding) while other areas are open to ambient atmosphere, allowing large parts to be built without requiring a fully enclosed chamber.
Solution Approach 2:
Atmospheric control is applied locally only where needed (at the weld pool and immediate vicinity) rather than requiring control of the entire build chamber. This allows selective protection of the molten metal while leaving the rest of the space open.
2Volume of moving object
If conventional manufacturing methods (casting, forging, machining) are used, then large parts can be produced, but material wastage is high and delivery times are long
Solution Approach 1:
The manufacturing approach changes from subtractive (machining) or formative (casting/forging) processes to additive welding deposition. This parameter change enables near-net-shape manufacturing of large parts with minimal material wastage while maintaining the capability to produce large dimensions.
3Device complexity
If additive manufacturing is performed in ambient atmosphere, then enclosed chambers are eliminated, but surface contamination increases due to oxygen exposure
Solution Approach 1:
Inert gas (such as argon) acts as an intermediary substance between the molten metal and the ambient atmosphere. The inert gas shielding directs a controlled atmosphere to the weld pool area, preventing oxygen contamination while allowing the build space to remain open.
Solution Approach 2:
A controlled inert gas atmosphere is created locally at the weld zone to protect the molten metal from oxidation and contamination, while the rest of the build space remains open to ambient atmosphere, eliminating the need for fully enclosed chambers.
4Productivity
If rapid cooling is applied to deposited weld beads, then production efficiency increases, but distortion increases due to thermal stress
Solution Approach 1:
The substrate and previously deposited layers are pre-heated before new weld beads are deposited. This preliminary heating reduces the thermal gradient between the new hot material and the existing structure, minimizing thermal stress and distortion while allowing rapid deposition to continue.
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 allows for increased production efficiency and reduced distortion in large-scale metal parts manufacturing, minimizing surface contamination and distortion, and enabling high-volume production of complex shapes without the need for enclosed chambers, thus overcoming size and environmental limitations of traditional methods.
Implementation Method 1
displacing the atmosphere within the immediate vicinity of the heat source with an inert gas atmosphere which produces a required flow rate
Implementation Method 2
engaging an induction heating and closed loop cooling apparatus synergic to a welding control system and pre-heating the substrate material including the deposited weld beads
Implementation Method 3
closed loop cooling apparatus synergic to a welding control system
Implementation Method 4
closed loop cooling apparatus
Implementation Method 5
deposit a sequence of one-dimensional weld beads of the weldable material onto the supporting substrate by an electric arc delivered by a high energy tungsten arc welding torch
Implementation Method 6
forming a computer-generated, direction specific, layered model of the part... deposit a sequence of one-dimensional weld beads
Data Source
AI summary
A method of manufacturing a metallic part in a weldable material by solid freeform fabrication comprising generating three dimensional model of the part, slicing the three dimensional model into a set of parallel, sliced layers and then dividing each layer into a set of one-dimensional pieces and, with reference to layered weld-bead geometry data, forming a computer-generated, direction specific, layered model of the part. The method also comprises uploading the layered model into a welding control system and directing the welding control system to deposit a sequence of one-dimensional weld beads of the weldable material onto the supporting substrate in a pattern required to form a first layer of the layered model and depositing a second welded layer onto the previous deposited layer in a configuration the same as the second layer, and repeating each successive weld bead until the entire part is completed. The method further includes displacing the atmosphere within the immediate vicinity of the heat source with an inert gas atmosphere which produces a required flow rate, and in which that inert atmosphere contains a maximum oxygen concentration, wherein the inert gas is delivered by an apparatus through a matrix of individual gas diffusers; and engaging an induction heating and closed loop cooling apparatus synergic to a welding control system and pre-heating the substrate material including the deposited weld beads, relevant to the type of weldable material, wherein induction heating and cooling cycles are applied constantly or pulsed from the first layer to the final layer, where optimal heating and/or cooling cycles of the weldable material are relative to the final desired part shape and microstructure.