Removable Blind Fastener with Telescopic Clamping
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Solution Overview
Problem
Conventional blind fasteners are bulky, obstructive, and have limited clamping pressure due to spring strength, posing challenges in automated assembly and alignment of large aircraft structures, where accurate alignment and one-sided operation are crucial.
Innovation Solution
A removable blind fastener comprising a telescopic design with adjustable fingers and a threaded member, allowing for axial movement and adjustable clamping force, enabling secure alignment and easy installation from one side without obstructing the work-piece surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional spring-loaded blind fasteners are used, then one-sided operation is enabled, but the fastener bulk is exposed and vulnerable, presenting an obstruction on the work-piece surface
Solution Approach 1:
The second member with adjustable fingers is nested within the hollow body of the first member. When the fastener is inserted into the work-piece hole, the telescopic mechanism allows the second member to be contained within the first member's hollow body, eliminating surface obstruction while maintaining one-sided operational capability through the external adjustment mechanism
Solution Approach 2:
The fastener employs a telescopic mechanism where the second member can axially move relative to the first member. This dynamic structure allows the fastener to transition between a compact state (when not in use) and an extended state (when clamping), enabling the body to be flush with the work-piece surface during operation while remaining non-obstructive when removed
2Duration of action of moving object
If conventional spring-loaded fasteners are used, then temporary clamping is achieved, but the maximum clamping pressure is limited by spring strength
Solution Approach 1:
The fastener uses an adjustable finger mechanism where the position of the finger can be changed to control the clamping force. By adjusting the finger position along the threaded aperture, the operator can vary the clamping pressure independently of spring limitations, allowing for both light temporary clamping and high-force secure fastening as needed
Solution Approach 2:
The adjustable finger provides a dynamic clamping mechanism that can be modified during operation. The finger can be positioned at different heights on the threaded aperture to change the mechanical advantage and clamping force, transitioning from light temporary holding to strong permanent-like fastening without changing the basic fastener structure
3Ease of operation
If the fastener body is exposed above the work-piece surface, then one-sided operation is simplified, but automated tool heads are impeded by protruding fasteners
Solution Approach 1:
The telescopic mechanism nests the second member within the first member's hollow body when not in use, creating a flush surface that allows automated tool heads to sweep across without obstruction, while maintaining the one-sided operational capability through the external adjustment interface
4Force
If high clamping force is applied with conventional fasteners, then secure fastening is achieved, but lateral pressure may damage the work-piece
Solution Approach 1:
The adjustable finger concentrates the clamping force at a specific local point on the work-piece surface rather than distributing it broadly. By positioning the finger tip precisely where needed and applying force only at that location, the fastener achieves high clamping force without creating harmful lateral pressure across the entire work-piece surface
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 provides precise alignment and controlled clamping force, reducing the risk of damage to work-pieces and allowing for efficient assembly processes by being flush with the surface, enabling the use of high torque without lateral pressure, and facilitating easy removal without access to the underside.
Implementation Method 1
a threaded member having a shaped head for engagement with the head of the first member and a threaded shaft with a finger engagement surface remote from the shaped head; the first member has a restriction at its head end to prevent the removal of the second member from the head end of the first member, such that the removable blind fastener comprises a unit of the first member, the second member and the threaded member
Data Source
Figure 1
Figure 2
Figure 3~4d
AI summary
A removable blind fastener comprising a first member (10) having an elongate body (11) with a head (12) at one end, a second member (20) adapted for axial movement relative to the first member, the second member having a threaded aperture (25) and at least one adjustable finger (22), the adjustable finger having a flange remote from the head of the first member and the finger being within the circumference of the hollow body of the first member in the first position of the adjustable finger and the flange extends beyond the circumference of the hollow body of the first member in the second position of the adjustable finger. Rotation of a threaded member (30) in a first direction causes axial movement of the second member relative to the first member in a clamping direction.