Captive Screw with Barbed Anchor for Adjustable Fixation
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Solution Overview
Problem
Captive fasteners are limited in their ability to be both permanently and removeably attached to a first member while engaging with a second member, and they do not allow for adjustable longitudinal and rotational motion between the members, which is necessary in certain mechanical configurations.
Innovation Solution
A captive screw with a barbed section that prevents removal after placement and an expandable anchor for permanent attachment, along with a threaded portion for adjustable friction to limit or encourage rotational and longitudinal motion, allowing for both permanent and removable attachment and adjustable positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a captive fastener is designed for permanent hold within a target assembly, then reliability of attachment is improved, but adaptability for repositioning and adjustment deteriorates
Solution Approach 1:
The captive screw is segmented into distinct functional zones: a threaded portion for removable attachment to the first member, a smooth portion for engagement with the second member, and a barbed portion for permanent anchoring. This segmentation allows each zone to perform its specific function independently, enabling both permanent and removable attachment characteristics simultaneously.
Solution Approach 2:
Different portions of the captive screw have different local qualities: the threaded portion provides reversible engagement, the smooth portion provides friction-based engagement, and the barbed portion provides irreversible engagement. This local differentiation of properties allows the single fastener to exhibit both permanent and removable attachment behaviors in different locations.
2Strength
If a captive fastener is designed with thread locking or press-fitting for secure joining, then strength of attachment is improved, but ease of operation for repeated insertion and removal deteriorates
Solution Approach 1:
The fastener is divided into zones with different engagement mechanisms: the threaded portion allows for easy repeated insertion and removal with strong attachment, while the barbed portion provides permanent anchoring that cannot be removed. This segmentation resolves the contradiction by applying different engagement strategies to different parts of the fastener.
Solution Approach 2:
The captive screw provides dynamic engagement characteristics: the threaded portion allows for dynamic insertion and removal operations, while the barbed portion provides static permanent fixation. This dynamic behavior enables the fastener to be easily operated for positioning while maintaining secure attachment.
3Reliability
If a captive fastener is designed to be permanently attached to a first member, then reliability of fixation is improved, but adaptability for adjusting longitudinal and rotational position deteriorates
Solution Approach 1:
The captive screw is segmented into a threaded portion that allows for adjustable positioning through repeated insertion and removal, and a barbed portion that provides permanent fixation once the desired position is achieved. This segmentation enables both position adjustment and reliable fixation to be achieved at different stages of the fastening process.
Solution Approach 2:
The threaded portion allows for preliminary positioning and adjustment of the captive screw to the desired longitudinal and rotational position before the barbed portion engages to provide permanent fixation. This preliminary action enables position adjustment before final securing.
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
Enables the captive screw to be repeatedly driven in and out for adjusting positions while preventing full disengagement, providing secure and adjustable fixation suitable for medical devices like endoscopes, allowing for both locked and movable configurations.
Implementation Method 1
the lower portion comprising a barbed portion, wherein an outer circumference of the barbed portion is flexible, wherein the captive screw is configured with a first attachment portion and a second attachment portion to attach to a first member of an auxiliary device
Implementation Method 2
the central middle portion comprising a threaded portion... the threaded portion for causing removable attachment to the first member... adjusting the friction between a first member and a second member to limit or encourage rotational and longitudinal motion
Implementation Method 3
an expandable anchor to hold a medical device in position and which is not removable after placement
Data Source
AI summary
An apparatus is presented comprising a captive screw comprising an upper portion, an upper middle portion, a central middle portion, a lower middle portion, and a lower portion, the central middle portion comprising a threaded portion, the lower portion comprising a barbed portion, the upper middle portion and the lower middle portion comprising a smooth portion, and the upper portion comprising a grip portion, wherein an outer circumference of the barbed portion is flexible, wherein the captive screw is configured with a first attachment portion and a second attachment portion to attach to a first member of an auxiliary device, and wherein the captive screw is configured to act as a set screw with respect to a second member of an auxiliary device.