Concentric Box Plastic Restraint Locking Mechanism
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Solution Overview
Problem
Plastic restraint devices are prone to damage when used on strong individuals due to weaknesses in their locking mechanisms, making them unreliable for secure restraint.
Innovation Solution
A plastic restraint device constructed from three integral sub-assemblies of single-piece plastic components, featuring a concentric box-within-a-box design with sloped teeth that distribute stress and prevent removal, enhancing strength and security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If plastic restraint devices use conventional locking mechanisms, then they are easier to manufacture and less expensive, but they are prone to damage when used on strong individuals
Solution Approach 1:
The restraint device is divided into three integral sub-assemblies (first strap assembly, second strap assembly, and handle), each constructed from a single piece of plastic. This segmentation allows each component to be optimized for its specific function while maintaining manufacturing simplicity through injection molding of individual parts.
Solution Approach 2:
The patent employs a concentric box-within-a-box design where the second box structure is nested inside the first box structure. This nested configuration distributes stress across multiple concentric layers, significantly enhancing the strength and resistance to damage of the locking mechanism while remaining manufacturable through standard plastic injection molding processes.
2Reliability
If plastic restraint devices use conventional locking mechanisms, then the device complexity is lower, but the reliability is reduced due to common failure points
Solution Approach 1:
The concentric box-within-a-box design eliminates common failure points by distributing stress across multiple nested structures. The inner box is surrounded by an outer box, creating redundant load paths that prevent single-point failures and significantly improve reliability.
Solution Approach 2:
Each sub-assembly is constructed as an integral unit combining multiple functions into single components. The box structures integrate locking, restraining, and stress-distribution functions, reducing the number of separate parts and potential failure points while maintaining reliability.
3Strength
If metal handcuffs are used to ensure robustness and tamper resistance, then strength and security are improved, but manufacturing cost increases significantly
Solution Approach 1:
The patent changes the material parameter from metal to plastic, specifically using high-strength plastic materials that can be molded into complex shapes. This parameter change maintains the necessary strength and robustness while dramatically reducing manufacturing cost and complexity compared to metal construction.
Solution Approach 2:
The device uses plastic as a composite material solution, leveraging modern high-strength plastic formulations that combine durability, flexibility, and cost-effectiveness. This composite approach replaces traditional metal construction while achieving comparable or superior performance for restraint applications.
Data Source
AI summary
An apparatus includes an elongated peg and box tube, the peg and box tube are coaxially aligned along a longitudinal axis of the respective peg and are concentric, first and second apertures extending through the peg and box tube, first and second respective arms within the peg each with a plurality of teeth from an exterior wall towards a second, opposing side of the peg directly adjacent one of the first and second apertures and a strap extending from each of the peg and box tube and from opposing longitudinal ends, wherein each of the straps has a plurality of notches extending perpendicular to a longitudinal axis of the strap, where each of the plurality of teeth of the respective arms engages one of the plurality of notches of a respective strap inserted through a corresponding one of the first and second apertures.