Wax Pattern Support Structure for Investment Casting
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Solution Overview
Problem
In investment casting, wax patterns are prone to breakage during the shelling process due to loads applied during ceramic slurry dipping and refractory sand coating, leading to defects in the casting.
Innovation Solution
A support structure comprising a support capping structure with a geometry matching the wax pattern's surface and a plurality of support braces extending from the capping structure to a base plate, which secures the wax pattern in a fixed position and distributes the load uniformly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If support structures are added to maintain wax pattern integrity during shelling, then pattern strength is improved, but device complexity increases
Solution Approach 1:
The support structure is divided into multiple discrete components: individual braces positioned at specific locations around the wax pattern, and a separate capping structure that sits atop the pattern. This segmentation allows each component to be optimized independently for its specific function while maintaining overall structural integrity without excessive complexity.
Solution Approach 2:
The support structure transitions from two-dimensional planar supports to three-dimensional spatial configuration with braces extending in multiple directions and a capping structure adding vertical dimension. This dimensional enhancement provides superior load distribution and pattern protection while maintaining manufacturing simplicity through standardized geometric forms.
2Stability of the object's composition
If support structures are used during shelling, then wax pattern stability is improved, but casting quality may deteriorate due to interference with solidification
Solution Approach 1:
The support structures are designed as temporary, removable elements that are completely extracted from the final casting. The braces and capping structure are positioned to provide necessary support during shelling but are configured to be removed or melted away without remaining in the final product, thus eliminating any potential interference with the cast part quality.
Solution Approach 2:
The support structures are installed in advance to protect the wax pattern during the critical shelling operation, then removed before the casting process begins. This preliminary protective action ensures pattern stability during manufacturing preparation while preventing any subsequent interference with the actual casting and solidification process.
3Strength
If multiple layers of ceramic slurry and sand are applied during shelling, then shell strength is improved, but load on wax pattern increases causing breakage
Solution Approach 1:
The support braces and capping structure act as intermediary elements between the accumulating ceramic shell and the wax pattern. These intermediaries bear the increasing load from multiple layers of slurry and sand, preventing direct transmission of these forces to the wax pattern and thereby preventing breakage while allowing the shell to achieve necessary strength.
Solution Approach 2:
The support structure is installed beforehand to cushion and absorb the increasing loads as ceramic layers are applied during shelling. This prior cushioning protection allows the wax pattern to withstand the cumulative weight of multiple thick layers of slurry and sand without breaking, enabling the formation of a strong ceramic shell.
Data Source
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AI summary
An approach for supporting a wax pattern (12) during investment casting. The approach described herein forms a support structure (30) to support the wax pattern (12) during investment casting. The support structure (30) has a capping structure (32) with a geometry that can match a profile of a lower region (18) of the wax pattern (12), and at least one support brace (38) extending outward from the support capping structure (32). The support structure (30) can be placed on a surface of the lower region (18). The support capping structure (32) can form a defined envelope (36) to enclose the lower region (18) of the wax pattern (12). The support structure (30) is connected to a base plate (22) by the support brace(s) (38). The capping structure (32) and the support brace(s) (38) secure the wax pattern (12) to the base plate (22) and distribute the load of the wax pattern (12) to maximize strength while minimizing the risk of a discontinuity in the wax or shell that could affect the casting process.