Hydro-formed Rail Gap Joint for Side Impact Load Transfer
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Solution Overview
Problem
In high volume production, variations in parts and tolerance stack-ups complicate assembly operations for joints between hydro-formed members and extruded components, leading to interference issues and inconsistent performance in side load impact tests for vehicle body structures.
Innovation Solution
A framed joint design that includes a hydro-formed rail, a bracket, and an extruded cross-car support with a defined gap to facilitate assembly and consistent test results, where the bracket is secured to the rail's inner surface and the extruded support is assembled in a spaced relationship to create a vertical alignment, allowing for efficient load handling and improved assembly efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hydro-formed members and extruded components are manually fitted by machining, mitering and MIG welding, then acceptable fit is achieved, but assembly complexity increases and productivity decreases
Solution Approach 1:
The hydro-formed rail is pre-formed with an integrated bracket during the hydro-forming process itself, rather than adding the bracket as a separate component requiring assembly. This preliminary action eliminates subsequent machining, mitering, and welding operations, thereby maintaining fit quality while dramatically improving productivity and reducing assembly complexity
2Strength
If multiple piece aluminum stampings are used at framed joints, then structural requirements are met, but assembly difficulty increases and additional assembly operations are required
Solution Approach 1:
The bracket and rail are merged into a single integrated hydro-formed component rather than being separate parts that require assembly. This merging maintains the structural integrity needed for framed joints while eliminating the assembly operations required for multiple piece stampings, thereby improving ease of operation without sacrificing strength
3Productivity
If tolerance stack-ups occur in high volume production, then assembly variations increase, but maintaining consistent side load impact test results becomes difficult
Solution Approach 1:
The bracket is pre-formed as an integral part of the rail during hydro-forming, which inherently controls the geometry and positioning. This preliminary action eliminates tolerance stack-ups that would accumulate through multiple separate assembly operations in high volume production, ensuring consistent side load impact test results while maintaining high productivity
Solution Approach 2:
The invention changes the manufacturing parameter from separate component assembly with tolerances to a single hydro-forming process that produces the bracket and rail as one integrated part. This parameter change eliminates the tolerance stack-up issue entirely, providing both high production volume capability and consistent test result reliability
Data Source
AI summary
A hydro-formed body side rail is assembled by a bracket to a front header. The front header is an extruded cross-car structural support that is joined to the body side rail by a framed joint. A gap is defined between the body side outer panel and the hydro-formed side rail relative to a lateral end of a front header. Side impact test loads are applied initially to the body side rail and compress the bracket. Compression of the bracket closes the gap and the impact loads are applied to the cross-car structural support.