Stacked-Head Tamper-Proof Screw for Easy Tightening
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Solution Overview
Problem
Tamper proof screws are inconvenient to use when they require specific tools for both tightening and loosening, which hinders their adoption and usability, especially when no removal is necessary.
Innovation Solution
A screw design featuring stacked screw heads with a first screw head for easy tightening using a common tool and a second screw head for secure fastening requiring a specific tool, where the connection between the neck portion and the screw heads has lower torsional endurance to facilitate separation and expose the second screw head, making it difficult to unscrew.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tamper proof screw uses a specific drive design that requires special tools for tightening and loosening, then the security effect is achieved and the screw becomes difficult to remove, but the ease of operation deteriorates and users experience inconvenience when they do not need to remove the screws
Solution Approach 1:
The screw head is segmented into two distinct parts: a first screw head with a common drive (e.g., Phillips, flathead) for easy tightening during installation, and a second screw head with a security drive (e.g., hex, Torx, proprietary pattern) for secure fastening. This segmentation allows the screw to provide both ease of operation during installation and security during service, resolving the contradiction between security and ease of operation.
2Reliability
If a tamper proof screw requires specific tools for tightening, then the security effect is achieved, but the device complexity increases due to the need for multiple tool types
Solution Approach 1:
The screw head is segmented into two distinct parts: a first screw head with a common drive (e.g., Phillips, flathead) for easy tightening during installation, and a second screw head with a security drive (e.g., hex, Torx, proprietary pattern) for secure fastening. This segmentation allows the screw to provide both ease of operation during installation and security during service, resolving the contradiction between security and ease of operation.
3Ease of operation
If the connection between the neck portion and screw heads has lower torsional endurance, then the first screw head can be separated to expose the second screw head for security, but the strength of the screw structure is reduced
Solution Approach 1:
The neck portion is designed with locally reduced strength characteristics compared to the screw heads. The connection between the neck portion and the screw heads has lower torsional endurance, creating a controlled weak point that allows the first screw head to be twisted off after installation. This local quality difference enables the transition from easy tightening (first head) to secure fastening (second head) while maintaining sufficient overall strength for the application.
Data Source
AI summary
A screw having stacked screw heads includes a screw shank portion with a thread and a screw head portion rigidly connected to each other. The screw head portion is driven to bring the screw shank portion to rotate. The screw head portion includes a first screw head and a second screw head. The first screw head has a first shaped groove on its top plane to receive an operating torque. A neck portion is connected to a bottom plane of the first screw head and a top plane of the second screw head. The second screw head has a second shaped groove on its top plane. The neck portion or the connection between the neck portion and the first screw head or the second screw head has lower torsional endurance than each of the first screw head and the second screw head.