Composite Tool Vacuum Seal via Segmented Mandrel
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Solution Overview
Problem
The manufacture of large composite structures, such as aircraft fuselages, faces challenges in achieving airtight seals due to the complexity and weight of conventional collapsible tools, leading to seal failures and increased costs.
Innovation Solution
A tool comprising a tapered support section and enclosable tool sections that form a self-supporting, airtight seal when the support section is retracted, using fibre-reinforced composite materials and a flexible enclosure means to ensure vacuum integrity and simplify sealing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional collapsible tools with multiple interconnecting parts are used to form large composite structures, then the tool can be dismantled to enable removal of the moulded structure, but the complexity of sealing between parts increases and seal failure occurs due to stress from material application and vacuum conditions
Solution Approach 1:
The tool is divided into a removable mandrel section and a fixed tool section, allowing the mandrel to be extracted independently for structure removal while maintaining a simpler sealing arrangement between the two sections
Solution Approach 2:
A flexible vacuum film is introduced as an intermediary sealing element that bridges the gap between the mandrel and tool sections, providing airtight sealing without requiring complex mechanical seal systems
2Area of stationary object
If the tool sections are made extremely large and heavy to accommodate large composite structures, then the structure can be formed, but the weight creates considerable stresses on the seals leading to seal failure
Solution Approach 1:
The tool is segmented into removable and fixed portions, allowing the heavy mandrel to be extracted after use, reducing the permanent weight burden on the sealing system
Solution Approach 2:
A flexible vacuum film is used instead of rigid sealing components, allowing the sealing surface to conform to the large tool geometry while distributing stresses evenly and preventing seal failure
3Extent of automation
If robotic positioning apparatus is used to wind composite material around the mandrel, then automated deposition can be achieved, but ensuring accurate material application and maintaining vacuum integrity becomes extremely difficult
Solution Approach 1:
The tool is segmented with the mandrel removable from the fixed sections, allowing automated material application on the fixed portions while maintaining vacuum integrity through the flexible film that accommodates robotic positioning movements
4Reliability
If complex sealing systems are used between tool parts to maintain vacuum integrity, then vacuum conditions can be applied, but the manufacturing process becomes very intricate and expensive
Solution Approach 1:
A flexible vacuum film serves as an intermediary sealing element that provides reliable vacuum integrity without requiring complex mechanical seal systems, simplifying the overall tool design while maintaining reliability
Solution Approach 2:
The flexible vacuum film conforms to the tool geometry and provides airtight sealing through its elasticity rather than complex mechanical components, reducing manufacturing complexity while maintaining vacuum integrity
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 solution allows for efficient and cost-effective manufacturing of large composite structures by eliminating the need for complex sealing systems and reducing stress on seals, ensuring precise application and curing of composite materials while maintaining vacuum integrity.
Implementation Method 1
non-ambient pressure conditions such as vacuum conditions are required to be applied to the material on the tool, either in autoclave or non-autoclave conditions, to facilitate consolidation of the material and removal of air from within the material during cure
Data Source
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AI summary
A tool (10) comprising a support section (12), a plurality of tool sections (14) beatable around the core section (12) to define one or more tool surfaces (16) on which structure material (C) is beatable to be moulded to form a composite structure, the support section (12) and enclosure means (18) being sealingly engagable to enclose the tool sections (14) and structure material (C) therebetween, thus allowing air to be withdrawn from between the enclosure means and the support section as part of the cure process of the structure material. Sealing the enclosure means (18) directly against the support section (12) obviates the need for the tool sections (14) to be sealingly interconnected.