Security Door Levering Resistance via Segmented Frame Design
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Solution Overview
Problem
Security door systems with security screens are susceptible to jemmy attacks, where intruders use tools like screwdrivers or crowbars to break open locks or hinges, creating a gap for unauthorized access.
Innovation Solution
A security door system featuring a door frame with elongate members, a mesh covering, and a wall frame with hinge members, along with various security members such as anti-lift elements, locking mechanisms, striker plates, hinge security plates, and security prongs that prevent levering by engaging with the door or wall frames, and an electrically operated locking mechanism for enhanced security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If security screens are used to prevent intruder impact and kicking, then impact resistance is improved, but the system becomes susceptible to jemmy attacks
Solution Approach 1:
The door frame is divided into multiple elongate members with distributed locking points along their lengths, rather than relying on a single locking mechanism. This segmentation allows the frame to resist levering forces at multiple discrete points, preventing the concentrated stress that enables jemmy attacks while maintaining impact resistance through the overall structural integrity of the segmented frame system
Solution Approach 2:
Different portions of the door frame members are provided with different local properties: some areas have locking mechanisms for security, while other areas have reinforced sections for impact resistance. The locking mechanisms are positioned at specific locations along the elongate members to optimize both jemmy attack prevention and impact resistance, with each local section tailored to its specific functional requirement
2Reliability
If multiple locking mechanisms are added to prevent jemmy attacks, then security is improved, but device complexity increases
Solution Approach 1:
The elongate door frame members serve multiple functions simultaneously: they provide the structural framework for the door, incorporate distributed locking mechanisms for security, and act as leverage-resistant structures against jemmy attacks. The locking mechanisms themselves are designed to perform both locking and anti-levering functions, reducing the need for separate components and thereby limiting complexity increase while improving reliability
3Reliability
If elongate door frame members with distributed locking points are used, then resistance to levering is improved, but manufacturing complexity increases
Solution Approach 1:
The door frame is segmented into standardized elongate members that can be manufactured independently using standard fabrication processes. Each member incorporates pre-positioned locking points and reinforcement features that are integrated during manufacturing, allowing for modular assembly that simplifies the overall manufacturing process while achieving distributed locking for enhanced levering resistance
Solution Approach 2:
The locking mechanisms and reinforcement features are pre-positioned and pre-assembled on the elongate door frame members during manufacturing, rather than being installed separately during door assembly. This preliminary action reduces on-site assembly complexity and ensures proper positioning of security features, making the system easier to manufacture and install while maintaining high security standards
Data Source
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AI summary
A security door system having a door that includes a door frame comprising elongate door frame members, each having a first holding channel formed therein, and a clamping portion spaced from the first holding channel. The door further includes a mesh covering an opening enclosed by the frame. In addition to the above, the security door system includes a wall frame comprising elongate wall frame members operably coupled to the door frame by one or more hinge members, the hinge members facilitating pivotable movement of the door between open and closed positions and one or a plurality of security members configured to prevent or inhibit levering of the door relative to the wall frame.