Asymmetric Anti-Pinching Sectors for RTM Injection Mold

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Solution Overview

Problem

The existing method of closing injection molds for manufacturing axisymmetric composite parts, such as gas turbine casings, results in pinching of fibers due to blisters forming during the compacting process, leading to poor sealing and defects in the finished part.

Innovation Solution

The use of angular sectors with protruding and recessed lower portions forming specific angles relative to the radial direction on the mold's annular base, which allows for parallel alignment during closure, reducing the risk of pinching and ensuring proper compacting of the fibrous preform without creating spaces between sectors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If angular sectors are used to close the mold and compact the preform, then the preform is compacted to final thickness, but fibers are pinched between adjacent sectors causing mold deterioration and pinch fiber defects

Engineering Contradiction:

Improvepreform compacting precisionVSAvoidfiber pinching and pinch fiber defects

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The angular sectors are designed with asymmetric lower portions where one lateral edge has a protruding portion and the other has a recessed portion. This asymmetric configuration ensures that when sectors are positioned adjacent to each other, the protruding portion of one sector fits into the recessed portion of the adjacent sector, eliminating gaps and preventing fiber pinching while maintaining effective compacting pressure distribution.

Inventive Principle:

Principle #4Asymmetry

2Productivity

If angular sectors are positioned to compact the preform, then compaction is achieved, but spaces subsist between sectors allowing blisters to penetrate and be pinched

Engineering Contradiction:

Improvemold closing efficiencyVSAvoidsealing quality between sectors

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The asymmetric design with protruding and recessed lower portions on adjacent angular sectors creates interlocking geometry that eliminates gaps between sectors during closing. This ensures continuous contact and sealing surfaces, preventing blister penetration while maintaining efficient mold closing operation.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The mold closing sequence is designed to position angular sectors in a predetermined order where sectors with protruding portions are positioned before those with recessed portions. This preliminary sequencing ensures that protruding portions engage with recessed portions of adjacent sectors, eliminating gaps before the final closing operation and preventing fiber pinching.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11648739B2Rtm injection mold and method using asymmetric anti-pinching sectors

Publication Date: 2023.05.16 SAFRAN AIRCRAFT ENGINES SAS

AI summary

An injection mold for the manufacture of an axisymmetric part of composite material including a mandrel supporting a fibrous preform and including an annular wall, and a plurality of counter-mold angular sectors assembled on the mandrel and intended to close the mold and to compact the fibrous preform wound on the mandrel. Each angular sector includes an annular base intended to come into contact with the fibrous preform. The annular base extends between the first and second lateral edges in a circumferential direction, the first lateral edge of the annular base of an angular sector being in contact with a second lateral edge of the annular base of an adjacent angular sector.