Segmented Mandrel for Bonding Complex Curvature Shells
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Solution Overview
Problem
Existing methods for bonding high-temperature axisymmetric shells with complex curvatures using the differential pressure bonding process require shells to be constructed in multiple sections, which reduces the surface area available for acoustic treatment and increases weight and part count due to girth seams and connecting hardware.
Innovation Solution
A tool comprising separable mandrel segments with a continuous axisymmetric inner surface allows for the bonding of metallic layers into a single-piece shell with complex curvatures, using a segmented mandrel assembly and differential pressure bonding process to eliminate the need for girth seams and maximize surface area for acoustic treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a one-piece mandrel is used for bonding shells with complex curvatures, then the shell can be produced as a single piece, but the mandrel cannot be extracted from the shell after bonding
Solution Approach 1:
The mandrel is divided into multiple separable segments that can be assembled around the shell during bonding and then disassembled for extraction. Each segment can be independently removed from the bonded shell, solving the extraction problem while maintaining the ability to form complex single-piece shells.
2Ease of operation
If shells are constructed in multiple sections to facilitate mandrel extraction, then the mandrel can be removed, but the surface area for acoustic treatment is reduced and weight increases due to girth seams
Solution Approach 1:
The mandrel is segmented rather than the shell, allowing the shell to remain as a single continuous piece without girth seams. The segmented mandrel components can be removed after bonding, enabling both easy extraction and production of seamless lightweight shells.
Solution Approach 2:
The segmented mandrel acts as an intermediary tool that facilitates the bonding process and can be removed afterward, leaving the shell as a single piece without permanent seams or connecting hardware.
3Ease of operation
If shells are constructed in multiple sections, then mandrel extraction is possible, but the part count and production time increase
Solution Approach 1:
The mandrel is divided into segments that can be quickly assembled and disassembled, enabling efficient extraction without requiring the shell to be built in sections. This reduces the number of bonding operations needed and decreases production time.
Solution Approach 2:
The segmented mandrel is designed to be pre-assembled in a configuration that allows easy extraction after bonding, eliminating the need for complex extraction procedures and reducing overall production time.
4Area of moving object
If a one-piece mandrel is used, then the shell surface area for acoustic treatment is maximized, but the mandrel cannot be separated from the shell
Solution Approach 1:
The mandrel is segmented into multiple removable parts, allowing the shell to be formed as a single continuous piece with maximum surface area for acoustic treatment. The segmented structure enables easy separation after bonding without compromising the shell's integrity or surface area.
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 the production of single-piece axisymmetric shells with complex curvatures, maximizing acoustic treatment surface area, reducing weight, and minimizing part count and production time by eliminating girth seam blockages and hardware connections.
Implementation Method 1
The differential pressure bonding process generally includes applying a pressure differential across an assembly of metallic layers to simultaneously compress and bond the materials together at an elevated temperature
Implementation Method 2
A bonding material disposed between the metallic layers bonds the sheets together such as by liquid interface diffusion bonding or brazing
Implementation Method 3
When the layered materials and bonding material are heated to the bonding temperature, the bonding material melts and fuses the layered materials together
Data Source
AI summary
A tool and method for bonding layers of a shell by the differential pressure bonding process. The tool and method includes a plurality of separable mandrel segments that combine to form a mandrel having a longitudinal axis, an outer surface, an upper end, and at least one substantially continuous inner surface. The inner surface has a substantially axisymmetric shape having complex curvature. In this embodiment, the tool further includes a retort configured to at least partially shroud the outer surface and upper end of the hollow body. The retort includes at least one vacuum port. The tool is configured to facilitate the compression of a plurality of layers of a multi-layer shell having complex curvature as the shell layers and an interdisposed bonding material are heated to an elevated bonding temperature.