Iso-Grid Forming With Support Structure
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Solution Overview
Problem
Existing methods for forming iso-grid structures in sheet metal, such as post-form chemical milling and machining, face challenges with filler material liberation and structural integrity during the forming process, especially when using stiffer materials that are prone to cracking and material not flowing properly.
Innovation Solution
A method involving filling iso-grid structure pockets with a filler material and attaching a support structure to the perimeter, which is thinned and stretched during shaping, to maintain the filler material in place and facilitate forming complex profiles without material liberation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a stiffer filler material is used to prevent pocket buckling during forming, then the structural integrity of the iso-grid pattern is improved, but the filler material becomes more prone to cracking and liberation during the forming process
Solution Approach 1:
A supporting sheet is introduced as an intermediary element between the filler material and the forming forces. The supporting sheet is attached to the rear surface of the iso-grid pattern and provides mechanical support during forming, allowing the use of stiffer filler materials without causing cracking or liberation. The supporting sheet absorbs the forming stresses and transfers them gradually to the filler material.
2Reliability
If supporting sheets are pinned near the center of the part to retain material, then material liberation is reduced, but intimate contact of the supporting sheet and iso-grid pattern throughout the forming operation is not ensured
Solution Approach 1:
The supporting sheet is segmented into multiple sections or zones, each attached to the iso-grid pattern at different locations including the perimeter and intermediate regions. This segmentation allows the supporting sheet to maintain intimate contact with the iso-grid pattern throughout the entire forming operation, ensuring uniform support and preventing filler material liberation across all areas of the part.
3Ease of manufacture
If post-form chemical milling or machining is used to create iso-grid patterns, then the patterns can be formed after shaping, but filler material liberation and structural integrity issues occur during the forming process
Solution Approach 1:
The supporting sheet is attached to the iso-grid pattern before the forming operation begins. This preliminary attachment ensures that the supporting sheet is in place to prevent filler material liberation during the forming process. The supporting sheet remains attached throughout forming, chemical milling, and machining operations, providing continuous protection and support.
Data Source
AI summary
A method of forming an iso-grid structure may include filling multiple pockets of the iso-grid structure with a filler material, attaching a support structure to the perimeter of the iso-grid structure, shaping the iso-grid and support structures, and removing the support structure from the iso-grid structure. The support structure may be thinned and stretched during the shaping process.