Movable Wall for Additive Powder Bed Stress Relief
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Solution Overview
Problem
Existing additive manufacturing processes, such as laser sintering and melting, often result in part fractures and distortions due to excessive pressure from the powder bed, as the powder bed exerts pressure on growing parts and restricts shrinkage, limiting the ability to produce large, fracture-free, undistorted components.
Innovation Solution
A powder bed apparatus with moveable chamber walls or build platforms that adjust forces on the object, using features like springs, actuators, or fluid pressure valves to compensate for thermal changes and relieve stress, allowing for controlled powder bed volume adjustments and reducing structural loading on built components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the powder bed exerts pressure on the growing part to maintain contact and support, then the part is supported during manufacturing, but the part experiences excessive pressure causing fractures and distortions
Solution Approach 1:
The chamber wall is made moveable rather than fixed, allowing it to dynamically adjust its position and the pressure it exerts on the part. The wall can move toward or away from the part based on thermal expansion/contraction, maintaining optimal support pressure without causing excessive stress that leads to fractures and distortions.
Solution Approach 2:
The system changes the physical state or parameters of the chamber wall (position, pressure) in response to thermal changes in the part. By monitoring thermal expansion/contraction and adjusting wall pressure accordingly, the system maintains supportive pressure while avoiding excessive forces that cause part failure.
2Stability of the object's composition
If the powder bed restricts shrinkage of the growing part, then the part is contained and supported, but the part cannot shrink freely causing fractures and distortions
Solution Approach 1:
The chamber wall transitions from a rigid constraint to a dynamic boundary that can move with the part. As the part shrinks or expands thermally, the wall moves accordingly, maintaining containment while allowing natural dimensional changes without inducing stress concentrations that cause fractures or distortions.
Solution Approach 2:
The moveable wall anticipates and counteracts the harmful effect of restricted shrinkage by being designed to move in response to thermal changes. This preliminary design consideration ensures the wall does not become a source of stress that would cause part failure during cooling and shrinkage.
3Stability of the object's composition
If the chamber walls are fixed to maintain structural stability, then the apparatus is simple and stable, but the powder bed cannot adjust volume to accommodate thermal changes
Solution Approach 1:
The chamber wall is designed as a moveable component rather than a fixed structure. This dynamic element allows the powder bed volume to adjust as the part undergoes thermal expansion and contraction, accommodating dimensional changes while the overall apparatus maintains stability through controlled, deliberate movement of the wall.
Solution Approach 2:
The moveable chamber wall serves multiple functions: it maintains containment of the powder bed, provides structural stability, and simultaneously allows volume adjustment to accommodate thermal changes in the part. This multi-functionality resolves the contradiction between stability and adaptability.
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
Enables the production of large, fracture-free, and undistorted parts by managing powder bed loading and accommodating dimensional changes during the additive manufacturing process, improving the quality and reliability of components like those for aircraft engines.
Implementation Method 1
compensate for thermal changes and relieve stress
Data Source
AI summary
An additive manufacturing apparatus for building an object is provided. The apparatus includes a build chamber having at least one chamber wall, a powder delivery mechanism, and a build platform. The build chamber and build platform defines while in operation a powder bed. At least one surface of the build chamber or build platform is moveable in a manner that is capable of adjusting forces on the object in the powder bed.