Locking Washer Assembly for Screw Head Alignment and Pretension
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Solution Overview
Problem
Existing locking washer assemblies face issues with misalignment, cracking, and loss of pretension due to improper adaptation to screw geometry, leading to uneven torque and clamp load distribution, and potential machining errors.
Innovation Solution
A locking washer assembly design with adjustable inner diameters and chamfers to securely engage with screw heads, preventing lateral movement and ensuring correct alignment, while preassembled washers with specific diameters and engagement mechanisms enhance stability and ease of use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the inner diameter of locking washers is adapted to the radius under the bolt head, then the washer can fit over the screw head, but the washer may misalign against the screw shank and the torque-tension ratio is affected
Solution Approach 1:
The locking washer is divided into two distinct parts: a first locking washer with a larger inner diameter that fits over the screw head radius, and a second locking washer with a smaller inner diameter that provides precise alignment with the screw shank. This segmentation allows each part to fulfill its specific function without compromising the other.
Solution Approach 2:
The first locking washer acts as an intermediary element between the screw head and the second locking washer. It bridges the gap between the screw head radius and the screw shank, allowing the second locking washer to align precisely with the shank while the first washer accommodates the head geometry.
2Reliability
If the through hole of the locking washers is too small, then the washer engages firmly with the screw, but the washer may cut into the screw head radius and consume torque
Solution Approach 1:
The engagement function is segmented between two washers: the first locking washer with its larger inner diameter engages with the screw head radius without cutting into it, while the second locking washer with its smaller inner diameter provides firm engagement with the screw shank. This prevents torque loss from machining the screw head.
Solution Approach 2:
Different parts of the locking washer system have different local qualities - the first washer has a larger inner diameter suited for engaging the screw head radius, while the second washer has a smaller inner diameter optimized for firm engagement with the screw shank. Each location has the appropriate geometry for its specific function.
3Loss of energy
If the inner diameter is enlarged to avoid cutting into the screw head, then torque loss is reduced, but the washer may laterally dislocate on the screw shank
Solution Approach 1:
The lateral stability function is assigned to the second locking washer with its smaller inner diameter that fits tightly on the screw shank, while the first locking washer with the larger inner diameter is free to accommodate lateral movements. This segmentation allows the system to reduce torque loss while maintaining lateral stability.
Solution Approach 2:
The first locking washer serves as a mediator that absorbs lateral movements and misalignments between the screw head and shank, allowing the second locking washer to maintain its precise fit on the shank without being subjected to lateral dislocation forces.
Data Source
Figure 1~1a
Figure 2~3
Figure 4~5
AI summary
It is proposed a locking washer assembly (1; 1') comprising a first locking washer (2, 2') and a second locking washer (3), wherein the first (2; 2') and second locking washer (3) comprise means (11) for engaging an element (16, 17) to be attached by means of a screw joint and further said first and second locking washer (1; 1') comprise means (12) for engaging each other, characterized in that the first locking washer (2; 2') comprises a central through hole that is larger than the central hole of the second locking washer (3). It is also proposed an attachment assembly comprising a screw (15.15', 15'') intended to be used with a locking washer assembly (1; 1') as mentioned.