Curved Locking Washer Profile for Stable Bolt Preload
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Solution Overview
Problem
Existing locking washers struggle to maintain sufficient spring force over a specific spring travel to counteract loosening in bolted connections due to settling and creep, especially when used with non-ferrous metals like cast aluminum, while ensuring a flat bearing surface and uniform contact pressure.
Innovation Solution
A locking washer design featuring intersecting circular arcs with different radii allows for full contact with the substrate, providing increased residual spring forces and a flat bearing surface, with adjustable spring action and material thickness variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a step is introduced on the underside of the disc to create initial spring force, then spring force is improved, but the outer edge of the surface of the outer ring section lifts off the base during further tightening
Solution Approach 1:
The disc body is designed with a continuously curved transition area instead of a sharp step, using circular arc profiles to eliminate abrupt geometric changes. This curvature allows gradual load distribution and prevents edge lifting while maintaining spring force characteristics
2Ease of manufacture
If the transition area has a smaller cross-section to achieve continuous transition, then the disc can be manufactured, but the disc has a tendency to gape and hold inclination at the outer edge
Solution Approach 1:
The cross-sectional area of the transition area is locally increased compared to conventional designs, creating a thicker, more robust transition zone. This local quality enhancement prevents gaping and inclination while maintaining the continuous transition for manufacturability
3Stress or pressure
If a flat contact surface is used to achieve uniform pressure distribution, then contact uniformity is improved, but the material is overstretched and the disc breaks in the transition area
Solution Approach 1:
The flat contact surface is replaced with a continuously curved surface defined by circular arcs. This curvature allows the material to gradually deform and distribute stresses along the curved path, preventing stress concentration and material failure while achieving uniform pressure distribution
4Reliability
If the disc body is designed with large outer diameter area to reduce gaping, then locking effect is improved, but material consumption increases
Solution Approach 1:
The geometric parameters of the circular arcs (radii, center positions) are optimized to achieve the desired balance between locking effect and material consumption. By adjusting these parameters, the disc maintains sufficient outer diameter area for reliable locking while minimizing excess material usage
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 ensures uniform contact pressure and enhanced residual spring forces, preventing loosening and maintaining clamping force, even with non-ferrous metals, while allowing a flat bearing surface.
Implementation Method 1
the locking washer must have sufficient spring force over a certain spring travel to compensate for a loss of preload
Data Source
Figure 1~3
Figure 4
AI summary
The invention relates to a locking washer for arrangement on a flat surface (4), with an annular disc body (1) having a convex profile from the inner edge to the outer edge, wherein the disc has a cross-section formed by at least two intersecting circular arcs (13, 14) with different radii (r1, r2).