Threaded Insert Assembly for Flush Sandwich Panel Fastening
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Solution Overview
Problem
Conventional methods for fixing inserts in composite sandwich panels, such as honeycomb or foam structures, are inefficient due to the need for multiple tools, potential delamination, and protrusion of the insert head, which can cause stability issues and complicate the assembly process.
Innovation Solution
A threaded insert with a deformable rim and a hooking tail featuring circumferential grooves and peripheral ribs, designed for mechanical connection with a surface skin, and an internal tube for tool cooperation, allowing for automated assembly and avoiding substance deposition on internal threads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional multi-part insert devices are used with deformation chambers and spacer sleeves, then mechanical connection to sandwich panel is achieved, but assembly time increases and assembly cost increases
Solution Approach 1:
The patent merges the threaded tubular rivet and spacer sleeve into a single integrated insert device. The insert comprises a body with an internal tube that has external threads, eliminating the need for separate deformation chambers and spacer sleeves. This single-piece construction reduces assembly steps and time while maintaining mechanical connection strength through the integrated structure.
Solution Approach 2:
The insert is segmented into functional zones: a body portion for insertion, an internal tube with external threads for mechanical connection, and a hooking tail with circumferential grooves and peripheral ribs for bonding. This segmentation allows each zone to perform its specific function efficiently, reducing overall assembly complexity.
2Reliability
If conventional insert devices are assembled with sandwich panel, then mechanical connection is established, but delamination or detachment of lower skin occurs
Solution Approach 1:
The patent introduces a hardenable substance as an intermediary bonding agent between the insert's hooking tail and the sandwich panel's lower skin. The circumferential grooves and peripheral ribs on the hooking tail provide enhanced bonding surfaces for this intermediary substance, creating a strong adhesive connection that prevents delamination and detachment of the lower skin.
Solution Approach 2:
The hooking tail features circumferential grooves and peripheral ribs with rounded contours that provide increased surface area and improved stress distribution for bonding. This curved geometry enhances the bonding interface between the hardenable substance and the panel, preventing delamination.
3Reliability
If insert head protrudes from panel surface, then mechanical connection is secured, but stability of fixed element decreases
Solution Approach 1:
The patent transitions the insert head from a protruding three-dimensional feature to a flush, coplanar surface feature. The body of the insert is designed to sit flush with the panel surface, eliminating protrusion while maintaining connection security through the internal tube's external threads and the hooking tail's bonding mechanism.
4Strength
If roughness and teeth are provided on hooking tail for hardenable substance cooperation, then resistance to tensile forces improves, but cracks in hardening substance occur
Solution Approach 1:
The patent replaces sharp teeth and roughness features with smooth, rounded circumferential grooves and peripheral ribs on the hooking tail. These curved features provide increased bonding surface area and improved stress distribution, enhancing tensile force resistance while preventing crack initiation in the hardening substance.
Solution Approach 2:
The patent changes the surface geometry parameters of the hooking tail from sharp, angular teeth to smooth, rounded contours with optimized curvature radii. This parameter change maintains bonding strength while eliminating stress concentration points that would cause cracks in the hardening substance.
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
The solution enables a strong, stable, and automated assembly of the insert in sandwich panels, reducing assembly time and costs while preventing delamination and ensuring the insert lies flush with the panel surface, enhancing structural integrity.
Implementation Method 1
a deformable rim by a fitting tool allowing a mechanical connection by deformation with a surface skin of the sandwich panel
Implementation Method 2
The clear area between the bottom of the sandwich panel and the insert is filled with a hardenable substance
Data Source
Figure 1~2
Figure 3~4A
Figure 4B~5
AI summary
Insert (1) intended to be assembled in a hole (15) of a sandwich panel (13), comprising a hollow cylindrical body (3) having a flanged end (11) deformable by a setting tool (101) allowing a mechanical connection by deformation with a surface skin (17a) of said sandwich panel (13), said insert (1) having a hook tail (5) in the extension of the cylindrical body (3) as well as an internal tube (25) intended to cooperate with the setting tool (101), characterized in that said hook tail (5) has at least one circumferential groove (7) and one peripheral rib (9), the circumferential groove (7) and the peripheral rib (9) each having a rounded transverse profile to be able to cooperate with a hardenable substance (111).