Lock Cylinder Key With Segmented Profile Groove Undercut
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Solution Overview
Problem
Existing key designs for lock cylinders are not sufficiently difficult to copy and contribute a limited number of locking secrets in a locking system.
Innovation Solution
The key features a profile groove with a first section having straight flanks and a second section with a profile extension, where the second section is located on the key tip, creating a deep contour within the locking cylinder that is not visible externally, along with a transition section that provides a continuous change in the profile groove, making copying more challenging and increasing the variety of locking secrets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a profile extension overlaps the profile groove to form an undercut, then key copying becomes more difficult, but the complexity of the key structure increases
Solution Approach 1:
The profile groove is divided into a first section with straight flanks and a second section with the profile extension creating an undercut. This segmentation allows the key to have different structural characteristics in different sections, providing both copy protection through the undercut and ease of manufacture through the modular design.
Solution Approach 2:
The key features different geometric properties at different locations: the first section has straight flanks for ease of manufacture, while the second section has the profile extension creating an undercut for copy protection. This local differentiation allows each section to optimize its function without compromising the other.
2Reliability
If the profile groove has a continuous variation over a large range of the shaft length, then key copying becomes more difficult, but the manufacturing precision requirements increase
Solution Approach 1:
The profile groove features a continuous variation in its geometry along the shaft length, creating a dynamic profile that is difficult to replicate. The transition section provides a smooth continuation between sections, making the overall profile challenging to copy while remaining manufacturable through controlled variation.
Solution Approach 2:
The profile groove incorporates continuous changes in geometric parameters (width, depth, flank angles) along its length. This parameter variation creates a unique profile that is difficult to replicate exactly, thereby enhancing copy protection while maintaining manufacturability through systematic parameter changes.
3Reliability
If the transition section extends over at least half of the shaft length, then the profile groove becomes harder to copy, but the manufacturing time increases
Solution Approach 1:
The transition section is designed to extend over at least half of the shaft length to create a comprehensive profile variation that is difficult to copy. This preliminary design decision ensures strong copy protection while the systematic approach to creating the transition section allows for efficient manufacturing through standardized processes.
4Reliability
If the two sections of the profile groove have different depths and widths, then key copying becomes more difficult, but the device complexity increases
Solution Approach 1:
The profile groove features asymmetric characteristics with the first section having straight flanks and the second section having the profile extension creating an undercut. The different depths and widths between sections create an asymmetric profile that is difficult to replicate, thereby enhancing copy protection while the systematic asymmetric design maintains manufacturability.
Data Source
Figure 1~2
Figure 3~6
AI summary
In a key (2) with a shaft (8) and a bow (7), a profile groove (11) is divided into two sections (13, 14). The profile groove (11) in the section (13) located near the bow (7) is straight and without an undercut. The section (14) located furthest from the bow (7) has an undercut (18). A transition section (15) is arranged between the two sections (13, 14) to ensure a smooth transition between the differently designed sections (13, 14). This gives the key (2) a particularly high level of copy protection.