Hook Bolt Lock with Elongated Symmetrical Opening
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Solution Overview
Problem
Conventional hook-bolt locks are prone to deformation and failure under shear forces, particularly around the corners of the bolt opening, making them vulnerable to forced entry and destruction.
Innovation Solution
The lock design features a hook bolt with a bolt opening and cross section that are elongated and symmetrical, reducing shear stresses by distributing forces as tensile stresses only in regions of low material thickness, and a modular bolt module with a guiding cam portion for enhanced stability and security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional rectangular bolt opening with sharp corners is used, then the lock structure is simple and easy to manufacture, but stress peaks occur at the corners under shear forces leading to deformation and failure
Solution Approach 1:
The bolt opening is designed with curved sides instead of sharp corners, creating a rounded or oval shape that eliminates stress concentration points. This curvature distributes shear forces more evenly across the material, preventing deformation and failure at corner regions while maintaining manufacturing feasibility through standard forming processes.
2Ease of operation
If material is removed to create countersunk bolt apertures, then countersunk bolts can be fully inserted, but local weak points are created around the apertures reducing overall strength
Solution Approach 1:
The lock case is designed with locally reinforced regions around the bolt apertures, adding material or structural support specifically at these critical locations. This local quality enhancement prevents the creation of weak points while still allowing countersunk bolts to be fully inserted, maintaining both ease of operation and overall structural strength.
3Reliability
If a hook bolt is pivoted to engage deeply in the striker plate, then locking security is improved, but the forend experiences compressive, shear and tensile stress leading to potential failure
Solution Approach 1:
The bolt opening with curved sides allows the hook bolt to pivot and engage deeply in the striker plate for improved locking security, while the curved geometry distributes the resulting compressive, shear and tensile stresses more evenly across the forend material, preventing stress concentration and potential failure at corner regions.
Data Source
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AI summary
A lock (1) comprising a hook bolt (8) which is mounted in the lock, pivotally movable between a retracted position and an extended position, a forend (18) exhibiting a bolt opening (34), through which the hook bolt (8) extends in the extended position. The lock further comprising a lock mechanism (6), which is connected to the hook bolt (8) for driving the hook bolt between the retracted and the extended position, whereby the bolt opening (34) and a cross section of the bolt (8), which cross section, in the extended position is arranged in the plane of the bolt opening (34), have similar elongated shapes having a longitudinal direction, each of which shapes is symmetrical and substantially convex at least in a direction perpendicular to the longitudinal direction, such that a width (W), measured perpendicular to the longitudinal direction of the elongated shapes, varies along a length (L) of each of said shapes. The elongated shapes comprise two mutually opposed short sides (52) and two mutually opposed long sides (54), wherein the width of the elongated shapes between the long sides is maximal in an intermediate region of the shapes between the short sides.