Sleeved Collet Fastener with Rotating Stud for Shear Relief
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Solution Overview
Problem
Previous blind fasteners are susceptible to shear stresses, leading to damage and difficulty in removing the stud, as the collet body's flexible arms do not collectively share shear strength, and the fingers can become deformed, making insertion and removal challenging.
Innovation Solution
A fastener system with a sleeve that encloses a collet body, featuring cantilever legs with feet that protrude through the sleeve openings, decoupling shear stresses from the collet body and allowing easy engagement and disengagement, while the stud's threaded section adjusts the clamping force, and an unthreaded section enables free rotation to prevent damage during removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the collet body's flexible arms are positioned tangentially at maximum distance from the shear force vector, then the flexible arms can easily flex and expand, but they resist very little shear force and become susceptible to damage
Solution Approach 1:
The sleeve acts as an intermediary component that absorbs and resists shear forces, protecting the cantilever legs from direct shear stress. The sleeve's rigid structure provides the necessary shear strength while allowing the cantilever legs to maintain their flexibility for expansion and contraction operations.
Solution Approach 2:
The fastener system is divided into distinct functional segments: the sleeve handles shear resistance and structural support, while the collet body with cantilever legs handles expansion and clamping. This segmentation allows each component to be optimized for its specific function without compromise.
2Force
If the stud is tightly clamped between the collet body and the upper structure, then the fastener provides strong clamping force, but the stud becomes difficult to remove and may become stuck
Solution Approach 1:
The sleeve serves as a mediator between the stud and the external environment, providing a controlled interface for stud insertion and removal. The sleeve's internal geometry and interaction with the collet body create a mechanism that maintains clamping force while facilitating stud extraction through rotational movement.
Solution Approach 2:
The fastening mechanism transitions from a static clamped state to a dynamic removal process. The stud can be rotated within the sleeve during removal, converting the static friction problem into a dynamic solution where rotational motion overcomes the clamping force gradually.
3Ease of manufacture
If the collet body is exposed during insertion and removal, then the fastener can be easily installed, but the fingers are susceptible to abrasive wear and deformation
Solution Approach 1:
The collet body is nested within the protective sleeve during insertion and removal operations. The sleeve acts as an outer protective shell that shields the vulnerable cantilever legs from abrasive contact with the bore surfaces, while still allowing the fastener to be installed through coordinated movement of the nested components.
Solution Approach 2:
The sleeve provides beforehand protection for the cantilever legs against abrasive wear during the insertion and removal processes. This protective enclosure is in place before any harmful contact can occur, preventing deformation and extending the service life of the flexible arms.
4Adaptability or versatility
If the flexible arms operate independently without sharing shear strength, then each arm can flex independently, but the collet body as a whole is susceptible to shear stresses
Solution Approach 1:
The system is segmented into the sleeve that provides collective shear strength and the collet body that provides independent arm flexing. This segmentation allows the rigid sleeve to bear the overall shear load while the flexible cantilever legs maintain their ability to expand and contract independently for clamping operations.
Solution Approach 2:
The sleeve acts as an intermediary structure that distributes and shares the shear stress across its entire surface area, protecting the individual cantilever legs from bearing the full shear load. This allows the legs to operate independently for adaptation while the sleeve provides the collective strength.
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 system enhances the longevity of the fastener by protecting the collet body from shear stresses and abrasive wear, allowing easy installation and removal, and varying clamping force without damaging the components.
Implementation Method 1
a stud extending through the crown opening and including a threaded section engaging with an interior threaded section in at least one of the collet body and/or the sleeve
Implementation Method 2
a cantilever leg extending from the crown and including a foot configured to mate with the sleeve opening when the fastener system is in an engaged configuration
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A fastener system shifting shear stresses away from a collet body and provides clamping action to targeted structures. The fastener system includes feet in the collet body that mate with openings in a sleeve at least partially surrounding the collet body. The sleeve or the collet body includes interior threads that engage with a stud that is configured to extend through the collet body and bend the feet such that they project outward from the sleeve openings in an engaged configuration.