Jacketed Core for Complex Internal Passages
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Solution Overview
Problem
Existing methods for forming components with internal passages, such as those in gas turbines, face challenges due to fragile ceramic cores that are difficult and expensive to produce, particularly when the length-to-diameter ratio and cross-sectional complexity increase, leading to cracking and production issues.
Innovation Solution
A method using a jacketed core with a hollow structure formed partially by additive manufacturing, where an inner core defines the internal passage within the component, reducing fragility and enabling the formation of complex shapes and high L/d ratios through a single integrated process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a ceramic core with large length-to-diameter ratio is used to define internal passages, then the internal passage can be formed in the component, but the risk of cracking or breaking of the core during handling and production increases
Solution Approach 1:
The core is divided into multiple segments that can be assembled together to form the complete core structure. This segmentation reduces the length-to-diameter ratio of individual core pieces, making them more resistant to cracking and breaking during handling while still enabling the formation of long internal passages through precise alignment and joining of segments
Solution Approach 2:
A mandrel is inserted inside the ceramic core to provide internal support and reinforcement. This nested structure prevents the core from collapsing or cracking under its own weight during handling and production, allowing for greater length-to-diameter ratios without compromising core integrity
2Shape
If a substantially non-linear ceramic core is used to define complex internal passages, then the internal passage shape can be achieved, but the risk of cracking or breaking increases due to tension from the core's own weight
Solution Approach 1:
The non-linear core is divided into multiple curved segments that can be manufactured with smaller radii of curvature. This segmentation reduces the tensile stresses that develop in long-span curved cores under their own weight, preventing cracking while maintaining the desired non-linear passage shape through precise alignment of segments
Solution Approach 2:
A mandrel is placed inside the non-linear core to provide continuous internal support along the curved path. This prevents the core from developing tensile stresses that would lead to cracking, enabling the formation of complex non-linear internal passages with tighter curves and more aggressive geometries
3Shape
If traditional ceramic core production methods are used, then cores can be produced, but substantially non-linear cores are difficult to produce due to difficulty in providing suitable pull planes and draft angles
Solution Approach 1:
The core is manufactured as multiple straight or gently curved segments that can be produced using standard mold designs with adequate draft angles and pull planes. These segments are then assembled to form the complete non-linear core, bypassing the need to manufacture complex non-linear shapes in a single piece and enabling precise geometric control
Solution Approach 2:
Mandrels with the desired non-linear geometry are manufactured beforehand and used as internal supports during core formation. These mandrels define the final passage shape and are removed after casting, allowing the core to be produced as simple linear segments rather than requiring complex non-linear mold cavities
4Use of energy by moving object
If a cross-section with non-smooth perimeter is used to increase wetted perimeter for heat transfer, then heat-transfer performance is improved, but stress concentrations increase the risk of local cracking
Solution Approach 1:
The core with non-smooth cross-section is divided into multiple segments with smoother transitions. This segmentation reduces the stress concentrations at sharp corners and perimeter variations, preventing local cracking while still maintaining the enhanced heat transfer performance through the increased wetted perimeter of the final assembled core structure
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 reliable and cost-effective formation of components with large length-to-diameter ratios, nonlinear shapes, and complex cross-sectional perimeters, reducing the risk of core damage and enabling precise internal passage features, thereby improving production efficiency and reducing costs.
Implementation Method 1
a hollow structure formed at least partially by an additive manufacturing process
Implementation Method 2
cooling the component material in the cavity to form the component
Data Source
AI summary
A method of forming a component having an internal passage defined therein is provided. The method includes positioning a jacketed core with respect to a mold. The jacketed core includes a hollow structure formed at least partially by an additive manufacturing process, and an inner core disposed within the hollow structure. The method also includes introducing a component material in a molten state into a cavity of the mold, and cooling the component material in the cavity to form the component. The inner core is positioned to define the internal passage within the component.