Monocrystalline Smelting Mold With Offset Support Rod

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Solution Overview

Problem

The mechanical strength of shell molds used in investment casting is compromised due to the presence of support rods that interfere with grain germination and propagation during monocrystalline solidification, leading to potential defects in the cast metal parts.

Innovation Solution

A mold design featuring a starting cavity with an inverted funnel shape and a laterally offset support rod, which connects to a chicane selector channel, ensures stable support and minimizes interference with grain selection, thereby promoting single-crystal growth without compromising the mold's integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If support rods are integrated into the mold to ensure mechanical strength, then the mold can support the casting cavity in high position, but the support rods interfere with grain germination and propagation during monocrystalline solidification

Engineering Contradiction:
Improvemechanical strength of the moldVSAvoidquality of monocrystalline solidification
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The invention extracts the support function from the traditional support rod configuration and relocates it to the base of the starting cavity. The starting cavity is designed with an enlarged base section that provides mechanical support to the mold structure, while the selector channel is positioned laterally offset from this base, eliminating interference with grain propagation.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the spatial arrangement by laterally offsetting the selector channel from the vertical axis of the starting cavity. Instead of the selector channel being centrally aligned (which would require support rods), it is positioned at a lateral distance, allowing grains to propagate horizontally away from the cavity base without encountering support rod obstructions.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Device complexity

If a traditional starting cavity design is used with centrally aligned selector channel, then the structure is simpler, but support rods must be added which compromise the monocrystalline solidification process

Engineering Contradiction:
Improvestructural simplicity of the moldVSAvoidintegrity of grain germination and propagation
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The invention introduces asymmetry in the spatial arrangement of the selector channel relative to the starting cavity. The selector channel is laterally offset from the central axis of the starting cavity, creating an asymmetric configuration that eliminates the need for support rods while maintaining structural integrity and enabling uninterrupted grain propagation.

Inventive Principle:
Principle #4Asymmetry

3Ease of manufacture

If support rods are used to maintain mold integrity, then the mold can be manufactured with standard techniques, but thermal homogeneity is compromised leading to parasitic grain germination

Engineering Contradiction:
Improvemanufacturability of the moldVSAvoidthermal homogeneity in the starting cavity
Core Design Contradiction:
Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The invention removes the support rods from the starting cavity and selector channel region, extracting the source of thermal disruption. The enlarged base of the starting cavity provides structural support without the thermal interference of support rods, enabling homogeneous thermal conditions necessary for reliable monocrystalline solidification.

Inventive Principle:
Principle #2Taking out (Extraction)

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 enhances the mechanical strength of the mold and achieves homogeneous thermal conditions, reducing the risk of parasitic grain germination and crack formation, resulting in high-quality monocrystalline metal parts with improved thermomechanical properties.

Implementation Method 1

When the metal solidifies in the mold, it gradually cools from the starting cavity, so as to cause the germination of the crystals therein

Methodology Applied
Scientific EffectCrystallisation: Crystallisation

Implementation Method 2

Directed solidification is understood in the present context as the control of the germination and growth of solid crystals in the molten metal during its transition from the liquid state to the solid state

Methodology Applied
Scientific EffectDirected solidification:

Implementation Method 3

the mold presents, under the molding cavity, a so-called starting cavity connected to the molding cavity by a selector channel

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 4

When the metal solidifies in the mold, it gradually cools from the starting cavity

Methodology Applied
Scientific EffectThermal gradient: Temperature Gradient

Data Source

PatentEP2983849B9Monocrystalline smelting mould
Publication Date: 2017.09.13 SN DETUDE & DE CONSTR DE MOTEURS DAVIATION (S N E C M A)
  • EP2983849B9 patent drawingFigure 1
  • EP2983849B9 patent drawingFigure 2
  • EP2983849B9 patent drawingFigure 3~4

AI summary

The invention relates to the field of monocrystalline smelting, and in particular to a monocrystalline smelting mould (1) including at least one moulding cavity (7), a starter cavity (10) having at least one first inverted funnel-shaped space (10a), and a separate second pedestal-shaped space (10b) at the bottom of the first volume and projecting substantially relative to said first space in at least one horizontal direction, as well as a selector channel (9) connecting said starter cavity (10) to said moulding cavity (7) and a supporting rod (20), offset laterally relative to said selector channel, and connecting the second space (10b) of the starter cavity (10) to the moulding cavity (7). The invention also relates to a smelting method using such a mould (1).