Locking Washer Tooth Layout for Soft-Surface Screw Joints
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Solution Overview
Problem
Existing screw connections face challenges in securely fastening to components with soft surfaces or reduced contact areas, such as aluminum or elongated holes, where traditional lock washers may not provide sufficient grip or prevent loosening.
Innovation Solution
A lock washer design featuring a fully circumferential toothing on the upper ring surface with a narrower width than the disk body, combined with a non-toothed area on the upper annular surface, allows for reduced surface pressure on the component while embedding teeth into the screw part for a positive and frictional connection, using materials like spring steel with hardness greater than 200 HV.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the full width of the upper annular surface is used for toothing, then the connection strength to the screw part is improved, but the surface pressure on the component increases causing the lock washer to dig into soft surfaces
Solution Approach 1:
The upper annular surface is divided into two distinct zones: a toothed area for engagement with the screw part and a non-toothed area that contacts the component. This local differentiation allows the toothed portion to provide strong mechanical interlocking while the non-toothed portion distributes the clamping force over a larger area, preventing excessive pressure on soft component surfaces.
2Stress or pressure
If the toothing width is reduced on the upper surface, then the surface pressure on the component is reduced, but the connection strength to the screw part decreases
Solution Approach 1:
The lock washer features a localized toothed area on the upper annular surface that is optimized for screw part engagement. The teeth are concentrated in a specific radial zone where they can effectively grip the screw part, while the remaining area remains non-toothed to provide pressure distribution. This localized approach maximizes connection strength where needed while minimizing surface pressure elsewhere.
3Device complexity
If a single washer design is used for both hard and soft surfaces, then the device complexity is reduced, but the reliability of the screw connection decreases on soft surfaces
Solution Approach 1:
The lock washer incorporates a differentiated upper annular surface with distinct toothed and non-toothed areas, creating a multi-functional design that adapts to different surface conditions. The toothed area provides mechanical interlocking for reliable connection, while the non-toothed area distributes pressure to protect soft surfaces. This single washer design thus achieves reliable performance across both hard and soft surface applications without requiring multiple specialized washers.
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
This design ensures a secure screw connection with reduced risk of independent loosening, even on soft surfaces, by distributing preload force effectively and preventing the lock washer from digging too deeply into the component, while maintaining sufficient frictional engagement.
Implementation Method 1
maintaining sufficient frictional engagement
Implementation Method 2
using materials like spring steel with hardness greater than 200 HV
Implementation Method 3
embedding teeth into the screw part for a positive and frictional connection
Implementation Method 4
preventing the lock washer from digging too deeply into the component, while maintaining sufficient frictional engagement
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
The invention relates to a locking washer for a screw connection (31) between a screw part (21) and a component (32), comprising an annular washer body (12) bounded by a circumferential outer rim (17) and an inner rim (18), a receiving bore (19) bounded by the inner rim (18) into which the screw part (21) can be inserted, an upper annular surface (16) provided on a top side of the washer body (12) which has a toothing (22), and a lower annular surface (14) provided on a bottom side of the washer body (12) which has a toothing (23) extending fully around the lower annular surface, wherein the toothing (22) on the upper annular surface (16) extends into a toothed area (23) which is fully formed.that the width of the toothed area (23) on the upper ring surface (16) is smaller than the width of the disc body (12) between the outer edge (17) and the inner edge (18), and that an untoothed area (27) is formed on the upper ring surface (16) between the toothed area (23) and the outer edge (17).