Captive Panel Fastener Structure for Stable Robotic Assembly
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Solution Overview
Problem
Existing captive panel fasteners in the electronics industry face instability during high-speed robotic assembly due to a large sidewall gap between the screw and ferrule, leading to misalignment and assembly errors, and prior solutions like o-rings or nuts add cost and complexity.
Innovation Solution
A panel fastener design featuring a collar and flange at the screw shank's bottom, combined with a stronger spring, provides stability to the screw in its retracted state, closing the gap between the screw and ferrule, allowing for misalignment compensation without the need for additional securing components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large sidewall gap is provided between the screw and ferrule to accommodate misalignment, then adaptability to misalignment is improved, but stability during high-speed robotic assembly deteriorates
Solution Approach 1:
The screw shank is segmented into multiple functional zones: an upper portion with a larger diameter that contacts the ferrule inner wall for stability, and a lower threaded portion with a smaller diameter that provides misalignment accommodation. This segmentation allows different sections to fulfill conflicting requirements simultaneously.
Solution Approach 2:
The screw features local quality variation along its length, with the upper shank having a larger diameter for stable contact with the ferrule, and the lower portion having a smaller diameter for misalignment tolerance. This localized differentiation resolves the contradiction between stability and adaptability.
2Stability of the object's composition
If a hold-down nut or o-ring is added to eliminate screw movement in the ferrule, then stability during assembly is improved, but device complexity and cost increase
Solution Approach 1:
The invention extracts the stabilization function from separate components (nuts or o-rings) and integrates it directly into the screw structure itself. The enlarged upper shank diameter provides the stabilizing contact with the ferrule without requiring additional parts.
Solution Approach 2:
The stabilization function is merged with the screw structure by making the upper shank diameter larger than the threaded portion diameter. This combines the fastening function and the stabilization function into a single integrated component.
3Stability of the object's composition
If a stronger spring is used to hold the screw in the retracted position, then mechanical stability is improved, but force required to manipulate the screw increases
Solution Approach 1:
The spring is pre-compressed to a greater extent because the screw starts in a retracted position. This preliminary compression stores energy that automatically propels the screw forward during assembly, reducing the manual force needed by the operator.
Solution Approach 2:
The system uses dynamic spring force that varies with screw position. The stronger spring provides maximum force when the screw is retracted and least force when extended, creating a dynamic balance that maintains stability while enabling easy manipulation.
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
This design ensures mechanical stability suitable for high-speed robotic assembly, reducing costs and complexity by eliminating the need for o-rings or nuts, while maintaining ease of manipulation and assembly accuracy.
Implementation Method 1
The screw is held in the retracted position by a light coil spring operatively positioned around the screw shank between the screw head and the top of the ferrule
Data Source
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AI summary
A panel fastener includes a screw that is captivated to a ferrule and urged toward a retracted position by a spring which operates between the screw head and the ferrule. When the screw is in the retracted position, a collar of enlarged diameter on the screw occupies the area adjacent an internal annular captivation ring of the ferrule. The screw includes a flange that bears directly against the captivation ring providing a stop to prevent removal of the screw. The spring is preferably a coil spring that is operative against an outer flange of the ferrule.