Foundry Mold Feed Arms Balance Thermal Contraction
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Solution Overview
Problem
Existing metal foundry processes often result in defects such as cracks and recrystallization in thin parts like turbomachine blades due to thermal contraction differences between the metal and the mold, leading to mechanical stresses and shrinkage defects.
Innovation Solution
A foundry mold design featuring feed arms with increasing cross-sectional areas to balance thermal contraction forces, allowing the metal to solidify and reduce shrinkage defects, while also enabling simultaneous molding of multiple parts and using a shell mold formed from refractory granules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional casting processes are used with standard mold designs, then the manufacturing process is simple, but cracks and recrystallization defects appear in thin parts due to thermal contraction differences
Solution Approach 1:
The mold is segmented into multiple independent feed arms (at least two feed arms) that can be designed with different cross-sectional areas. This segmentation allows each feed arm to independently manage thermal contraction forces, preventing the development of harmful tensile stresses in thin parts while maintaining overall mold functionality.
Solution Approach 2:
Different regions of the feed arms are designed with different cross-sectional areas to optimize their function. The feed arms have varying cross-sections along their length, with larger areas at certain positions to provide structural support and balance thermal contraction forces, while allowing controlled solidification patterns that prevent defects in specific critical areas of the casting.
2Reliability
If the mold retains the ends of the part during cooling, then the part structure is maintained, but tensile forces generate cracks and local recrystallizations
Solution Approach 1:
Multiple feed arms are positioned to act as counterbalancing structures during thermal contraction. As the metal cools and contracts, the feed arms with appropriate cross-sectional areas provide counteracting forces that balance the thermal contraction forces, preventing the development of harmful tensile stresses that would cause cracks and recrystallization in the part structure.
Solution Approach 2:
The cross-sectional area of the feed arms is specifically designed and varied to change the mechanical and thermal properties of the mold structure. By adjusting the cross-sectional parameters of the feed arms, the mold can control the distribution of thermal stresses during cooling, transforming the harmful tensile forces into manageable compressive or balanced forces.
3Manufacturing precision
If feed arms with uniform cross-section are used, then the mold design is simple, but shrinkage defects occur due to improper solidification propagation
Solution Approach 1:
The cross-sectional area of the feed arms is deliberately varied along their length to control the solidification process. By changing the cross-sectional parameter, the mold ensures that solidification propagates from regions of smaller cross-section to regions of larger cross-section, following a controlled directional pattern that prevents shrinkage defects while managing thermal contraction forces effectively.
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
The mold design effectively reduces cracks and recrystallization by balancing thermal contraction forces, preventing shrinkage defects and enhancing the quality of thin parts like turbomachine blades, while allowing for efficient production of multiple parts in a single mold.
Implementation Method 1
the different thermal contraction rates of the metal and the mold material can generate mechanical stresses to the point of causing the appearance of defects, and in particular cracks, in the solidified metal
Implementation Method 2
cooling and solidification of the metal in the molding cavity before demolding the solidified metal
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
The invention relates to the field of foundries and more particularly a foundry mold (1) comprising at least one molding cavity (2) and a pair of supply arms. The molding cavity (2) extends along a horizontal axis (X), from a first end (2a) to a second end (2b), and the first pair of supply arms comprises a first supply arm (3), oriented in a substantially vertical direction and connected to the first end (2a) of the first molding cavity (2), and a second supply arm (4), substantially parallel to the first supply arm (3) and connected to the second end (2b) of the first molding cavity (2). The invention also relates to a method for manufacturing the mold (1) and a foundry method using the mold (1).