Segmented Injection Mold Core for Composite Box Extraction
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Solution Overview
Problem
The difficulty in extracting a core from a closed box structure in resin transfer molding (RTM) for composite material parts, such as fan blade platforms, due to the size mismatch between the core and the opening section, complicates the unmolding process.
Innovation Solution
An injection mold core designed as a wedge with three distinct elements assembled together, each with a maximum section smaller than the opening section, allowing for extraction by withdrawing the elements sequentially, and featuring dovetail or screw connections for stability and alignment, along with extractor tools and fastening mechanisms to facilitate easy removal and prevent resin infiltration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-piece core is used inside the closed box, then the core provides structural support and alignment, but the core cannot be extracted from the box due to size mismatch between the core and opening section
Solution Approach 1:
The core is divided into multiple separate elements (first element, second element, third element) that can be inserted and removed independently. Each element has a maximum section size smaller than the opening section, enabling sequential extraction from the closed box while maintaining structural support and alignment functions during the molding process.
2Ease of operation
If the core is divided into multiple elements, then the core can be extracted from the box, but the assembly complexity increases
Solution Approach 1:
Multiple core elements are combined through dovetail joints that provide both mechanical connection and alignment guidance. The dovetail structure merges the functional requirements of structural support, alignment, and extractability into a coordinated assembly where elements work together to maintain box positioning while allowing sequential removal.
Solution Approach 2:
The dovetail joints are pre-designed with specific geometric relationships that guide the assembly process. The tenons and grooves are configured to automatically align elements during assembly, and the joint geometry is optimized to facilitate controlled extraction sequences without requiring complex removal operations.
3Strength
If dovetail joints are used to assemble core elements, then the connection strength and alignment improve, but the manufacturing complexity increases
Solution Approach 1:
Dovetail joints are applied selectively at specific locations where core elements connect, rather than throughout the entire structure. The joint design is optimized for local connection requirements, providing sufficient strength and alignment where needed while minimizing overall manufacturing complexity. The trapezoid-shaped tenons and complementary grooves are designed to achieve effective connection with standard machining operations.
Data Source
AI summary
The invention provides an injection mold core (100) for making a composite material part having a closed box, the core being in the shape of a wedge that is to be inserted inside a closed box (12) of at least one fiber preform into which a matrix-precursor fluid is to be injected, the core presenting both an opening right section (106) through which the core is to be unmolded from the box of the preform after the matrix has set, and also a maximum right section (108) of greater size than the opening right section, the core comprising at least three distinct elements (110, 112, 114) that are assembled together, each core element presenting a maximum right section of size that is smaller than the opening section.