Locking Threaded Fastener Assembly for Vibration-Resistant Reuse
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Solution Overview
Problem
Threaded fasteners often loosen over time, especially under vibrations or loads, and existing locking solutions like nylon lock nuts, thread compounds, and wire locks have drawbacks such as non-reusability, improper application risks, and installation difficulties.
Innovation Solution
A locking fastener assembly comprising a fastener, a locking washer with a locking tab and stop, and a locking member that interfaces with the stop to prevent loosening, allowing secure fastening and easy unlocking using common tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional lock washers are used to inhibit a fastener from loosening, then the fastener is protected from immediate loosening, but the threaded fasteners can still loosen over time depending upon the loading experienced
Solution Approach 1:
The locking mechanism is divided into separate functional components: a locking washer with a locking tab and a locking member with a locking surface. This segmentation allows each component to perform its specific locking function independently, with the locking tab engaging the locking surface to prevent rotation while the fastener maintains its clamping force.
Solution Approach 2:
The locking washer acts as an intermediary component between the fastener and the workpiece. The locking tab on the washer engages with the locking surface on the locking member, creating a mechanical interference that prevents loosening without requiring direct modification of the fastener or workpiece threads.
2Reliability
If wire locks are used to provide a secure locking mechanism, then the locking is repeatable, but it can be time consuming to remove and install
Solution Approach 1:
The locking mechanism is designed to be self-actuating through the natural rotation and seating of the fastener. As the fastener is tightened, the locking washer rotates and the locking tab engages with the locking surface automatically, eliminating the need for separate locking operations or special tools for installation and removal.
Solution Approach 2:
The locking washer is pre-configured with the locking tab in a specific orientation and position before installation. This preliminary positioning ensures that during normal fastener installation, the locking tab will naturally engage with the locking surface on the locking member, providing immediate locking action without requiring additional steps.
3Reliability
If nylon lock nuts or thread compounds are used to secure threaded fasteners, then the fasteners are locked, but the threaded fasteners are not readily reusable once disassembled
Solution Approach 1:
The locking washer is designed as a sacrificial component that can be easily replaced. The locking tab and locking surface engagement mechanism allows the fastener itself to be reused, while the locking washer can be swapped out as a separate, low-cost component to maintain secure locking without compromising fastener reusability.
Data Source
AI summary
A locking fastener assembly comprising a fastener having a threaded portion, and a head having a first end and a second end axially spaced from the first end, the second end comprising a fastening surface and a locking washer recess. The locking fastener assembly further comprises a locking washer disposed at least partially within the locking washer recess, the locking washer comprising a locking tab extending in a first direction and a stop biased in a second direction opposing the first direction, wherein the locking tab is operable to lock rotation of the locking washer relative to an item being secured upon a torqueing rotation and a loosening rotation of the fastener. A locking member is supported by the fastener, and operable to interface with the stop of the locking washer upon the loosening rotation of the fastener to lock the fastener relative to the item being secured.