Spin Resistant Threaded Insert for Thin-Walled Blind Applications
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing threaded fastener systems for blind applications in thin-walled materials face challenges in preventing spinning and withdrawal of threaded inserts, while minimizing workpiece distortion and maintaining visual appeal.
Innovation Solution
A threaded insert with an aggressive knurl pattern on the outer diameter and underside, combined with a hollow body featuring a plastically deformable first section and a threaded second section, which forms an enlarged portion on the blind side to prevent withdrawal and spinning, and internal threads for receiving fasteners.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a threaded insert is used in blind applications for thin-walled materials, then threaded fastening is enabled, but the insert may spin or rotate within the hole
Solution Approach 1:
The patent applies local quality by providing knurls only at specific locations (underside of the head and/or outer diameter of the body) rather than uniformly across the entire insert. This localized knurling provides spin resistance exactly where needed during installation, while maintaining a smooth surface elsewhere for proper deformation and retention.
Solution Approach 2:
The knurls are pre-formed on the insert before installation, creating preliminary engagement features that will dig into the workpiece material during the installation process. This preliminary preparation ensures immediate spin resistance as the insert is being set, without requiring additional installation steps.
2Reliability
If the workpiece is deformed to create an enlargement to prevent withdrawal, then retention is improved, but visual appeal is reduced
Solution Approach 1:
The patent moves the retention mechanism to another dimension by forming the enlarged portion on the blind side of the workpiece, opposite the visible side. The knurls on the visible side provide spin resistance during installation, while the deformation on the blind side provides withdrawal resistance without affecting the visual appearance of the visible side.
Solution Approach 2:
The patent segments the functions of spin resistance and withdrawal resistance into different locations: knurls on the visible side handle spin resistance during installation, while the enlarged portion formed on the blind side handles withdrawal resistance. This segmentation allows each function to be optimized independently without compromising the other or the visual appearance.
3Reliability
If aggressive knurls are used to increase spin resistance, then spin out values improve, but workpiece material is damaged
Solution Approach 1:
The aggressive knurls are applied only locally at specific positions (underside of head and/or outer diameter) rather than across the entire surface. This concentrated local quality provides maximum spin resistance exactly where the insert contacts the workpiece during installation, while minimizing the total amount of material affected and damaged.
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 significantly increases spin resistance and prevents withdrawal of the threaded insert, ensuring secure fastening without distorting the workpiece, thus maintaining its visual integrity.
Implementation Method 1
the aggressive knurls on the outer diameter of the body in conjunction with knurls under the head 'dig' into the parent material, thus filling the voids between the knurls and resulting in a substantial increase in spin out values
Implementation Method 2
a portion of the anchor device on the blind side of the workpiece is plastically deformed into a bubble or secondary flange
Data Source
AI summary
A threaded collapsible insert is utilized for insertion into a hole in a workpiece for subsequent installation of a threaded fastener. The insert has a axially-aligned opening extending for most or all of the entire length of the body of the insert. The hollow body has a first section and a second section, where the wall thickness of the first section is less than the wall thickness of the second section, such that the first section preferentially collapses upon application of a linear force to the insert. The second section comprises internal threads for engaging the fastener. The head member has a top side and an underside. The underside of the head member may comprise a plurality of knurls radiating outwardly on the underside of the flange. The outside of the first section may also comprise a plurality of axially aligned rib members extending from the proximal end to the distal end.