Independent Handling Accessory for Turbomachine Casting
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Solution Overview
Problem
The lost-wax casting technique for turbomachine elements, particularly with the source casting principle, often results in defects like cracking and recrystallized grains due to mechanical interactions between the parts being formed and handling accessories, such as a handling ring, which can degrade the metallurgical health of the parts.
Innovation Solution
A cluster-shaped model and shell design that includes a handling accessory independent of the metal supply circuit, allowing for separate casting and handling, with a central descender and source supply conduits for source casting, and a handling ring that is not in fluid communication with the shell elements to prevent mechanical interference during solidification and cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a handling ring is used as a feeding system in direct contact with parts to be formed, then the cluster can be handled at different stages of manufacturing, but mechanical interactions during solidification and cooling cause defects like cracking and recrystallized grains
Solution Approach 1:
The patent divides the feeding system into separate functional zones: a handling ring for cluster manipulation and independent feeding channels for metal supply. This segmentation allows the handling ring to perform its mechanical function without interfering with the metallurgical solidification process, as the feeding circuits are now independent and do not rely on direct contact between the handling ring and parts.
Solution Approach 2:
The patent extracts the feeding function from the handling ring structure. The handling ring is removed from direct contact with the parts, and feeding is achieved through separate conduits that connect the pouring cup to the mold cavities. This extraction eliminates the harmful mechanical interactions while preserving the handling capability of the ring structure.
2Force
If the handling ring mass is equivalent to the parts mass, then the cluster can be adequately supported, but strong mechanical interactions occur during solidification causing defects
Solution Approach 1:
The patent segments the support and feeding functions into separate systems. The handling ring provides structural support with appropriate mass, while independent feeding conduits deliver metal to the cavities. This segmentation allows the ring to provide necessary mechanical support without creating harmful interactions during solidification, as the feeding path is now separated from the handling structure.
3Productivity
If source casting principle is used with a handling ring, then gravity-fed casting can be implemented, but the handling ring degrades metallurgical health of parts
Solution Approach 1:
The patent extracts the feeding function from the handling ring, allowing the ring to serve purely as a handling device while independent conduits handle the metal feeding. This extraction enables gravity-fed source casting to proceed without the handling ring interfering with the metallurgical process, resolving the conflict between productivity and reliability.
4Strength
If internal stresses are generated in parts during solidification, then single-crystal solidification occurs, but recrystallized grains are generated
Solution Approach 1:
The patent removes the source of harmful internal stresses by extracting the feeding function from the handling ring. Without the mechanical constraints and interactions of a contact-based feeding system, the parts can solidify with minimal internal stresses, maintaining single-crystal structure without generating harmful recrystallized grains.
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 design reduces the risk of defects like cracking and recrystallized grains by minimizing mechanical stress and thermal gradients, maintaining the metallurgical health of the parts and allowing for efficient handling without degrading the parts' quality, while also reducing the handling ring's size and metal mass.
Implementation Method 1
the principle of gravity-fed casting of molten metal is well known. This involves pouring the metal from above into the mold cavities designed to form the turbomachine parts
Implementation Method 2
there is a strong risk that the ring will mechanically interact with the parts during solidification and/or cooling, which can lead to crack or core displacement defects on the parts when the forces are sufficient, but also, in the case of single-crystal solidification, to the generation of recrystallized grains due to the internal stresses generated in the parts
Data Source
Figure 1~2
AI summary
The invention relates principally to a cluster model and a shell (1) for the production, by lost wax casting, of a plurality of turbomachine elements, the shell (1) comprising a central sprue (3) that is fluidically connected to a casting cup (2) for receiving the molten metal, and a plurality of shell elements (4). The shell (1) is characterized in that it further comprises a plurality of bottom feed conduits (5) for the shell elements (4) and a handling accessory shell (6) that is independent of the plurality of shell elements (4) and of their metal supply circuit, such that there is no fluidic connection to the shell elements (4), the handling accessory shell (6) being fluidically connected to the central sprue (3) so as to allow top-pour casting of the handling accessory shell (6).