Plastically Deformable Washer for Screw Play Compensation
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Solution Overview
Problem
Existing screw connections struggle to effectively compensate for play between the screw head and workpiece, leading to potential loosening and inability to secure thin plates firmly without exact thickness matching, and existing washers are inadequate for play compensation due to their small thickness.
Innovation Solution
A screw connection design featuring a workpiece with thin plates and a screw shank with a hole-forming tip, where the unthreaded shank section's length is less than the sum of the workpiece and washer thickness, allowing for plastic deformation of the washer to compensate for play, ensuring a secure and play-free connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a corrugated washer is used to prevent screw loosening, then the screw is secured against reverse rotation, but the washer's small thickness limits its ability to compensate for play between the screw head and workpiece
Solution Approach 1:
The patent changes the material parameter of the washer from elastic (spring steel) to plastically deformable material, allowing the washer to be permanently deformed during installation. This plastic deformation enables the washer to compensate for play between the screw head and workpiece, while the corrugated structure maintains the anti-loosening function. The washer thickness can be increased without compromising its primary functions.
2Stability of the object's composition
If the workpiece thickness is made very large to prevent deformation, then the workpiece becomes stable and thick, but this increases the overall device size and complexity
Solution Approach 1:
The patent introduces a plastically deformable washer as an intermediary element between the screw and the workpiece. This washer absorbs the deformation that would otherwise need to occur in the workpiece itself. The washer can be compressed and deformed plastically to compensate for thickness variations and play, while the workpiece maintains its original stable dimensions without needing to be excessively thick.
3Reliability
If the unthreaded shank section length is increased to accommodate thicker washers, then play compensation is improved, but the screw connection complexity increases
Solution Approach 1:
The patent changes the material parameter of the washer to plastically deformable material, which fundamentally alters how play compensation is achieved. Instead of requiring a precisely matched unthreaded shank length equal to the washer thickness, the plastic deformability allows the washer to adapt to various thicknesses and play conditions. This provides a wider range of compensation capability without requiring precise dimensional matching, thereby reducing connection complexity.
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 allows for play compensation over a wide range, preventing screw loosening and ensuring a secure connection even with varying workpiece thicknesses, as the plastic deformation of the washer maintains the connection without further deformation force, providing sufficient pull-out resistance.
Implementation Method 1
the washer consists of a material which is selected such that the washer is plastically deformable when the screw connection is made
Data Source
Figure 1~2
Figure 3~4
AI summary
A washer (14) and a threaded assembly (22) between a screw (30) and a workpiece (42) are disclosed. The washer (14) is offset up to an angle (a) with respect to a flat initial state, such that said washer has an insert thickness (De) that is substantially greater than the initial thickness (Da) thereof. The washer (14) is made of a malleable material. The length (Lg) of an unthreaded shank section (40) of the screw (30) is smaller than the sum of the thickness (Dw) of the workpiece (42) and the insert thickness (De) of the washer (14), and essentially not smaller than the sum of the thickness (Dw) of the workpiece (14) and the insert thickness (Da) of the washer (14). When the last thread of the screw (30) leaves the workpiece (42) on being screwed in, the force previously exerted on the washer (14) by the feed of the screw is zero. The washer (14) has been plastically deformed thereby, such that said washer retains the flattened state thereof and bridges the space between the workpiece (42) and the screw head (34) free from play. The workpiece (42) and the washer (14) thereby remain firmly clamped between the head (34) and the thread (36) of the screw (30), and the prevention of inverse rotation is ensured.