Segmented Compliant Build Table for Low-Stress DED Fixtures
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Solution Overview
Problem
Conventional additive manufacturing processes, such as directed energy deposition (DED) systems, face challenges in reducing residual stress on fixtures and parts during fabrication, especially for large parts, which can lead to high costs and potential part failure due to sudden stress release.
Innovation Solution
The use of a compliant fixture with a plurality of sectors forming a ring on which a cylindrical part is built, allowing the layers of the part to expand and shrink freely, thereby reducing excessive residual stress formation. The fixture segments are not physically connected, enabling radial movement to accommodate thermal cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional rigid fixtures are used to support large parts during DED manufacturing, then the part can be securely held, but excessive residual stress accumulates in both the fixture and the part leading to deformation and cracking
Solution Approach 1:
The fixture is divided into multiple independent segments arranged in a ring, allowing each segment to move independently to accommodate thermal expansion and contraction of the part during DED manufacturing, thereby reducing residual stress while maintaining support
Solution Approach 2:
The fixture segments are designed to be movable rather than rigidly fixed, enabling dynamic adjustment during the manufacturing process to accommodate thermal cycles and reduce stress accumulation in both the fixture and the part
2Manufacturing precision
If rigid fixtures are used to constrain the part during fabrication, then manufacturing precision can be maintained, but sudden stress release causes part failure
Solution Approach 1:
The ring fixture is segmented into multiple independent sections that can move relative to each other, allowing the part to expand and contract thermally during DED manufacturing while maintaining positional accuracy and preventing sudden stress release
Solution Approach 2:
The fixture design changes the mechanical constraints from rigid fixed positions to controlled movable positions, allowing thermal expansion and contraction while maintaining manufacturing precision through the geometric constraints of the ring structure
3Reliability
If compliant fixtures with movable segments are used, then residual stress is reduced, but the device complexity increases
Solution Approach 1:
The fixture is segmented into multiple identical modular units arranged in a ring, where each segment has the same simple structure with a roller or support element, reducing individual segment complexity while achieving overall compliant behavior through the assembly
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 effectively reduces residual stress in both the fixture and the part, preventing deformation and cracking, while also optimizing material usage and reducing costs by ensuring the fixture is utilized efficiently.
Implementation Method 1
the fixture segments are permitted to move radially to permit expansion and shrinkage of the component
Implementation Method 2
DED apparatuses use a focused energy source, such as a laser or electron beam, to melt the feedstock material
Implementation Method 3
DED apparatuses use a focused energy source, such as a laser or electron beam, to melt the feedstock material
Implementation Method 4
where such melted material solidifies and fuses with other deposited materials, forming the component layer-by-layer
Data Source
AI summary
A build table assembly for supporting a component, the build table assembly including a base having an upper surface, a frame extending from the upper surface of the base, the frame defining an upper wall; a rim formed on the upper wall of the frame, and a plurality of fixture segments positioned on the rim opposite the upper wall of the frame, the plurality of fixture segments defining an arcuate build surface on which the component is built, the plurality of fixture segments spaced apart from one another.