Tapered Threaded Fastener Collar for Repeatable Clamp Load
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Solution Overview
Problem
Conventional fasteners face issues such as loosening under vibration, cross-threading, variable clamp load, and difficulty in disassembly, which affect their reliability and efficiency in assembly and maintenance.
Innovation Solution
A multi-piece fastener design comprising a fastening collar and a pin with a tapered threaded portion, where the collar is deformed onto the pin's threads to secure the fastener, allowing easy assembly and disassembly while maintaining a consistent clamp load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional threads are used, then assembly is simple, but the fastener loosens under vibration and pivoting conditions
Solution Approach 1:
The fastener is divided into two separate components: a pin with tapered threaded portion and a collar. The collar deforms onto the pin to create a locked connection, separating the insertion function (pin) from the locking function (collar). This segmentation allows the fastener to resist loosening under vibration while maintaining simple assembly through the two-piece design.
Solution Approach 2:
The collar transitions from a free state during insertion to a deformed locked state during operation. The dynamic deformation process allows the collar to engage the tapered threads and lock securely, providing vibration resistance while keeping the initial assembly simple. The collar can later be unlocked by applying torque to reverse the deformation.
2Reliability
If conventional threads are used, then assembly is straightforward, but cross-threading occurs during assembly
Solution Approach 1:
The tapered threaded portion has an asymmetric geometry where the taper angle and thread profile are designed to self-align. As the collar deforms onto the pin, the asymmetric taper guides the threads into proper alignment, preventing cross-threading. The taper ensures that only the correct thread orientation engages, making accurate thread engagement inevitable during assembly.
3Reliability
If conventional threads are torqued, then clamp load is achieved, but friction variability causes significantly variable clamp load
Solution Approach 1:
The invention changes the fundamental parameter of thread geometry from parallel to tapered. The tapered threaded portion creates a mechanical advantage that translates collar deformation directly into axial clamp load on the workpiece. This parameter change eliminates the friction variability issue because the load is applied through deformation rather than thread friction, resulting in consistent and predictable clamp load.
4Reliability
If a lock bolt is used, then a permanent joint is created with desirable clamp load, but the fastener is difficult to disassemble for servicing
Solution Approach 1:
The collar's locked state is dynamic and reversible through applied torque. During installation, the collar deforms onto the pin to create a permanent-looking joint. During disassembly, applying torque to the collar reverses the deformation, unlocking the fastener. This dynamic characteristic allows the joint to appear permanent during operation but be easily disassembled when servicing is needed.
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 design provides a repeatable clamp load, prevents cross-threading, and facilitates efficient installation and disassembly, enhancing the fastener's reliability and usability in various applications.
Implementation Method 1
The inner collar surface of the fastening collar is configured to be deformed onto the tapered threaded portion and secured to the shank
Implementation Method 2
The shank comprises a tapered threaded portion. The fastening collar is configured to be removable from the shank of the pin after deformation by applying a torque to the external collar surface
Implementation Method 3
The inner collar surface of the fastening collar is configured to be deformed onto the tapered threaded portion and secured to the shank
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A fastener comprising a pin and a collar. The pin comprising a shank comprising a tapered lock groove thread profile; and a head portion configured to receive a torque. The collar configured to be deformed onto and secured to the shank, wherein the collar comprises an external surface configured to receive a torque such that the collar can be removed from the shank after deformation.