Double-Acting Cam Fastener Assembly for Vibration Locking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing fasteners for high vibration applications lack effective anti-back-out mechanisms that can securely retain fasteners under dynamic loads, leading to potential loosening and failure.
Innovation Solution
The improved fastener assembly incorporates an elongated fastener body with cam and slip surfaces on both the fastener body and annular lock washer, designed to provide enhanced locking functionality through cam interactions and rotational resistance, ensuring secure retention even under vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fasteners are used in high vibration applications, then the fastening structure is simple, but the fasteners loosen and fail under dynamic loads
Solution Approach 1:
The fastener assembly is divided into distinct functional components: a fastener body with cam surfaces and a separate lock washer with corresponding cam surfaces. This segmentation allows each component to be optimized for its specific function while working together to prevent loosening under vibration.
Solution Approach 2:
The fastener assembly incorporates dynamic cam surfaces that actively engage and lock during vibration events. The cam surfaces are designed to interact dynamically, creating a locking action that increases during vibrational loads rather than failing, transforming the static fastener into a dynamically adaptive locking system.
2Strength
If cam surfaces with large radial angles are used to prevent back-out, then locking strength is improved, but the radial angle ratio between cam and slip surfaces becomes excessive
Solution Approach 1:
The invention optimizes the radial angle parameters of the cam surfaces within a specific range (greater than 10 degrees but maintaining a ratio less than 4.5:1). This parameter optimization ensures sufficient locking strength while avoiding excessive angles that would be difficult to manufacture and assemble accurately.
Solution Approach 2:
Different regions of the cam surfaces have different radial angles optimized for their specific functions: the locking cam surfaces have larger radial angles for strong engagement, while the slip surfaces have smaller radial angles for smooth operation. This local optimization of geometric parameters achieves both strength and manufacturability.
3Reliability
If ridge height between cam and slip surfaces is increased to enhance locking, then anti-back-out capability is improved, but manufacturing complexity increases
Solution Approach 1:
The ridge height between cam and slip surfaces is optimized to a specific minimum threshold (at least 0.08 mm) rather than being excessively large. This parameter optimization provides sufficient anti-back-out capability while keeping the geometry within practical manufacturing tolerances and capabilities.
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 effectively prevents back-out and loosening by utilizing cam and slip surfaces that interlock under axial loads, providing a secure and reliable fastening solution for applications under vibration.
Implementation Method 1
The inner washer surface comprising a plurality of circumferentially spaced washer cam surfaces extending radially between the inner washer peripheral edge and the outer washer peripheral edge; each of the washer cam surfaces being inclined relative to an imaginary plane orientated normal to the rotational axis
Implementation Method 2
the inner washer surface comprising a plurality of circumferentially spaced washer slip surfaces extending radially between the inner washer peripheral edge and the outer washer peripheral edge
Data Source
AI summary
A fastener comprising a body and a lock washer to be positioned between the body and a work surface, the washer having a plurality of circumferentially spaced cam surfaces, each being inclined relative to a plane normal to the center axis within a cam radial angle, alternating circumferentially about the center axis with a plurality of circumferentially spaced slip surfaces, each being inclined relative to the plane within a slip radial angle, each of the cam surfaces intersecting with two adjacent slip surfaces at a radial ridge and a radial valley, wherein the cam radial angle is greater than the slip radial angle and a radial angle ratio between the cam and slip radial angles is less than or equal to about 4.5, and the ridge having a ridge height relative to the valley greater than or equal to about 0.08 mm.