Lattice Structure Mold Assembly for Complex Internal Passages

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Solution Overview

Problem

Existing methods for forming components with internal passages face challenges such as precise core positioning, fragility of ceramic cores, high production costs, and the need for subsequent drilling processes, which are time-consuming and limited in producing complex passage curvatures.

Innovation Solution

A mold assembly using a lattice structure with a selectively altered composition, where a channel is defined through the lattice to position a core, allowing the core to extend within the mold cavity and define the internal passage, and the lattice is formed from a material that is partially absorbable by the molten component material to achieve local variations in material performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a ceramic core is used to define the internal passage, then the internal passage can be formed, but the core is difficult to position precisely with respect to the mold cavity

Engineering Contradiction:
Improvecore positioning precisionVSAvoidmold assembly complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The core is nested within the lattice structure, which itself is positioned within the mold cavity. This nested arrangement allows the core to be precisely positioned indirectly through the lattice structure's positioning features, such as alignment channels or engagement surfaces, without requiring direct positioning mechanisms on the core itself.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The lattice structure serves as an intermediary between the mold cavity and the core. Instead of positioning the core directly in the mold cavity, the lattice structure acts as a mediator that holds the core in the correct position through its designed geometry and positioning features, thereby achieving precise core positioning.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a ceramic core is used to define the internal passage, then the internal passage can be formed, but the core is fragile and difficult to handle without damage

Engineering Contradiction:
Improvecore integrityVSAvoidcore handling ease
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The lattice structure acts as a protective shell or framework around the fragile ceramic core. This external structure provides mechanical support and protection during handling and the casting process, preventing the core from breaking while allowing it to maintain its essential function of defining the internal passage.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The system becomes a composite structure where the fragile ceramic core is combined with the more robust lattice structure (which may be made of metal or other stronger materials). This composite arrangement allows the weak component (core) to perform its specific function while being protected and supported by the stronger component (lattice structure).

Inventive Principle:
Principle #40Composite materials

3Manufacturing precision

If a ceramic core is used to define the internal passage, then the internal passage can be formed, but the production cost increases

Engineering Contradiction:
Improveinternal passage formationVSAvoidproduction cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The lattice structure is designed to be removable or dissolvable after serving its positioning function. This allows the expensive lattice structure to be reused or discarded after a single use, while the core successfully defines the internal passage. The ability to remove the lattice structure eliminates the need for expensive permanent fixtures or complex post-processing.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The lattice structure is pre-positioned in the mold cavity before the core is inserted. This preliminary action ensures that the core will be automatically positioned correctly when inserted, eliminating the need for expensive precision positioning mechanisms or complex assembly procedures during the actual casting process.

Inventive Principle:
Principle #10Preliminary action

4Adaptability or versatility

If drilling is used to form the internal passage, then the passage can be created, but the process is time-consuming and cannot produce complex curvatures

Engineering Contradiction:
Improvepassage shape complexityVSAvoidpassage formation time
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The internal passage geometry is pre-defined by the core and lattice structure assembly before the casting process begins. The core is shaped to match the desired final passage geometry, including any complex curvatures, and is positioned in advance. This eliminates the need for time-consuming post-casting drilling operations and allows complex shapes to be formed directly during casting.

Inventive Principle:
Principle #10Preliminary action

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 enables precise and cost-effective formation of components with internal passages, reduces fragility issues, and allows for the creation of complex passage shapes, while eliminating the need for separate core support removal and drilling processes.

Implementation Method 1

the lattice is formed from a material that is partially absorbable by the molten component material

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Data Source

PatentEP3181266B1Method and assembly for forming components having internal passages using a lattice structure
Publication Date: 2018.10.24 GENERAL ELECTRIC CO
  • EP3181266B1 patent drawingFigure 1
  • EP3181266B1 patent drawingFigure 2
  • EP3181266B1 patent drawingFigure 3

AI summary

A mold assembly (301) for use in forming a component (80) having an internal passage (82) defined therein is provided. The component is formed from a component material (78). The mold assembly includes a mold (300) that defines a mold cavity (304) therein. The mold assembly also includes a lattice structure (340) selectively positioned at least partially within the mold cavity. The lattice structure is formed from a first material (322) that has a selectively altered composition in at least one region (380) of the lattice structure. A channel (344) is defined through the lattice structure, and a core (324) is positioned in the channel such that at least a portion (315) of the core extends within the mold cavity and defines the internal passage when the component is formed in the mold assembly.