Barrel Composite Injection Tooling for Undercut Demolding
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Solution Overview
Problem
The challenge of demolding aeroengine casings with a barrel shape, particularly those with varying diameters, is hindered by the narrowing upstream section, preventing the final part from being extracted using conventional RTM injection molds.
Innovation Solution
The development of injection tooling with a support insert having a junction slope greater than the maximum slope of the inner face, combined with sectorized inserts and a central radial barrel part, allows for simplified demolding by ensuring the inserts fill the non-demoldable portion and facilitate removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional RTM injection mold is used for a barrel-shaped casing, then the mold can be airtight and provide proper support, but the narrowing upstream section prevents the final part from being removed from the mold
Solution Approach 1:
The mold is divided into two separate parts: a first part that forms the support for the fibrous preform and a second counter-mold that is deposited on the preform. This segmentation allows the first part to remain in place providing support and airtightness, while the second part can be removed to enable demolding of the barrel-shaped casing.
Solution Approach 2:
The counter-mold is extracted as a separate removable component from the support structure. By taking out the counter-mold, the patent enables the final part to be removed from the mold without compromising the airtightness and support provided by the first part during the injection and polymerization processes.
2Shape
If the mold is designed with a barrel shape to match the casing geometry, then the final part shape is achieved, but the upstream section cannot be extracted due to the narrowing
Solution Approach 1:
The mold is segmented into a stationary first part and a removable second counter-mold. This allows the barrel-shaped geometry to be accurately formed while enabling the upstream section to be extracted after polymerization, as the counter-mold can be removed without damaging the finished casing.
Solution Approach 2:
Instead of trying to extract the entire mold assembly, the patent inverts the approach by making the counter-mold removable while leaving the support structure in place. This inversion enables the casing to be demolded by removing the counter-mold first, then extracting the casing from the support structure.
3Device complexity
If a single-piece tubular fiber preform is used, then the manufacturing process is simplified, but the demolding of barrel-shaped parts becomes problematic
Solution Approach 1:
The mold is segmented into a first part that maintains support for the single-piece tubular fiber preform and a second counter-mold that can be removed. This segmentation preserves the simplicity of the preform structure while enabling demolding of the final barrel-shaped part by removing the counter-mold.
Solution Approach 2:
The first part of the mold acts as an intermediary support structure that remains in place during the polymerization process, while the second counter-mold serves as a temporary form that can be removed. This intermediary approach allows the single-piece preform to be successfully demolded without compromising its structural simplicity.
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
Enables successful demolding of complex-shaped casings without increasing the number of parts or steps, ensuring the final part is not damaged during handling.
Implementation Method 1
Once injected, the resin is polymerized by heating the mold
Implementation Method 2
a vacuum created if necessary
Data Source
Figure 1
Figure 2
AI summary
Tooling for injecting a polymer resin into a fibrous preform for manufacturing a rotating part made of composite material (20), comprising a barrel shape with a recessed diameter (20CE) of smaller diameter and defining the rotating part in an upstream and a downstream portion of the recessed diameter, the upstream portion comprising an intermediate portion with undercut (20B), in which injection tooling, in order to enable the barrel-shaped part to be removed from the mould once the polymer resin has been injected and has polymerised, the injection tooling firstly comprises a tapered shaft (32) comprising a first shaft portion (32A) in direct contact with an inner surface (20Ei) of the rotating part portion downstream of the recessed diameter and a second shaft portion (32B), and secondly, a sectored insert (40) an outer surface of which matches an inner surface (20Di, 20Bi, 20Ai, 20Ci) of the rotating part portion upstream of the recessed diameter and an inner surface of which is in direct contact with the second shaft portion on which the sectored insert rests, the first shaft portion comprising a natural back taper enabling withdrawal of the central conical shaft upstream and the inner surface of the sectored insert having an inclination strictly greater than a maximum slope of an outer surface of said sectored insert corresponding to the upstream intermediate portion with undercut of the rotating part, so as to enable withdrawal of said sectored insert upstream.