Preload-Controlled Lockbolt Assembly With Swaged Collar Locking
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Solution Overview
Problem
Existing fastening systems, such as two-piece swaged fasteners, face challenges in securely attaching workpieces with consistent preload and efficient installation, particularly in applications like aerospace and satellite panels, where reliability and weight reduction are critical.
Innovation Solution
A lockbolt fastening system comprising a pin member with a threaded portion, a lock portion, and a pull portion, along with a swage collar that is swaged into the lock grooves of the pin member, allowing for secure attachment and visual indication of installation through break-off of the pull portion at a breakneck groove.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional two-piece swaged fasteners are used, then installation is simple, but preload consistency and reliability are insufficient
Solution Approach 1:
The fastener is divided into distinct functional segments: a pin member with threaded portion, smooth cylindrical shank portion, lock portion, and pull portion; and a separate swage collar. This segmentation allows each part to perform its specific function optimally while maintaining overall reliability and preload consistency.
Solution Approach 2:
The pin member is pre-configured with specific geometric features including lock grooves in the lock portion and pull grooves in the pull portion before installation. These pre-formed features enable controlled deformation and locking actions during the installation process, ensuring consistent preload application.
2Manufacturing precision
If traditional fastening systems are used, then installation time is reduced, but weight savings and preload accuracy are compromised
Solution Approach 1:
The invention replaces traditional torque-based mechanical fastening with a deformation-based locking mechanism. The swage collar is crimped onto the pin member, causing controlled plastic deformation that engages the lock grooves and secures the joint. This substitution eliminates the need for torque-tension acceptance testing while providing more accurate and consistent preload.
Solution Approach 2:
The fastener utilizes controlled plastic deformation parameters during installation. The swage collar is deformed beyond its elastic limit to permanently engage with the lock grooves, creating a rigid mechanical lock. This parameter change from elastic to plastic deformation ensures irreversible securing and consistent preload application.
3Reliability
If the pin member includes multiple portions and grooves, then locking reliability improves, but manufacturing complexity increases
Solution Approach 1:
The pin member features a smooth cylindrical shank portion with precise geometric curvature that transitions between the threaded portion and lock portion. This curved geometry facilitates controlled deformation during installation and ensures uniform stress distribution, improving manufacturing consistency and locking reliability.
Solution Approach 2:
The smooth cylindrical shank portion acts as an intermediary element between the threaded portion and the lock portion. This intermediate section with its specific diameter and curvature serves as the deformation zone during installation, mediating the transition from elastic to plastic deformation and ensuring reliable engagement of the lock grooves.
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 provides accurate preload, reduces installation time, and allows for weight savings by enabling workpieces to be sized based on preload, while eliminating the need for torque-tension acceptance, enhancing reliability and efficiency in secure fastening.
Implementation Method 1
a swage collar adapted to be swaged into the at least one lock groove of the lock portion of the pin member
Implementation Method 2
the pull portion is adapted to break off from the pin member at the breakneck groove
Data Source
AI summary
A fastener including a pin member having a shank portion, a threaded portion having a thread, a lock portion having at least one lock groove, and a pull portion located having at least one pull groove. The threaded portion is adapted to be engaged threadedly with a threaded hole of a workpiece to install the pin member therein. The fastener includes a swage collar adapted to be installed into the at least one lock groove of the lock portion to secure a plurality of workpieces. The pull portion is adapted to break off when the fastener is installed.