Sliding Strip Hook Bolt Catch for Deformation Compensation
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Solution Overview
Problem
Existing hook bolt catches in doors fail to utilize their full working height due to deformation and operational limitations, resulting in reduced anti-burglary protection, and existing designs lack sufficient resistance to break-ins using special tools.
Innovation Solution
A catch structure featuring a frontal strip with a catch opening and a securing element comprising an inner and outer slidable strip, where the securing element's opening matches the hook bolt's trunk shape and dimensions, preventing withdrawal by special tools, and allowing locking only through rotation of the hook bolt.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire working height of the hook is used for anti-burglary protection, then anti-burglary resistance should be improved, but door leaf deformation and drooping make it impossible to maintain appropriate process tolerances, reducing the effective working height to approximately 50%
Solution Approach 1:
The catch is divided into two independent slidable strips (inner and outer strips) that can move separately. This segmentation allows each strip to compensate for door leaf deformation independently, maintaining the form-fit engagement with the hook bolt trunk throughout the full working height of the hook, thereby resolving the contradiction between utilizing full hook height and maintaining manufacturing precision.
Solution Approach 2:
The slidable strips are designed to move dynamically in response to door leaf deformation and hook bolt insertion. The strips can slide to accommodate dimensional changes while maintaining the form-fit opening configuration, enabling the system to adapt to tolerance variations and fully utilize the hook's working height for security.
2Ease of operation
If the height of the catch opening is made relatively large for operational reasons, then ease of operation is improved, but the functional level of anti-burglary protection is significantly reduced
Solution Approach 1:
The slidable strips can dynamically adjust their position: they slide apart to accommodate the hook bolt trunk during normal operation, and come together to form a tight form-fit opening during locked state. This dynamic behavior allows a larger catch opening height for ease of operation while maintaining form-fit engagement for anti-burglary protection when locked.
Solution Approach 2:
The opening maintains form-fit dimensions specifically at the critical engagement zone where the strips meet, while allowing greater height overall for operational access. The local form-fit quality at the engagement point provides anti-burglary protection without requiring the entire opening to be small.
3Device complexity
If a simple catch design is used, then device complexity is reduced, but resistance to brake-in with special tools is insufficient
Solution Approach 1:
The catch uses two simple slidable strips instead of a complex single-piece mechanism. The segmentation into inner and outer strips creates a form-fit engagement system that resists brake-in tools, as the strips can move independently to maintain engagement while preventing tool insertion and manipulation.
Solution Approach 2:
The combination of two slidable strips creates a composite locking mechanism where the interaction between the strips forms the security feature. This composite structure provides enhanced brake-in resistance compared to a single simple strip, while remaining mechanically simple and easy to manufacture.
Data Source
Figure 1
Figure 2
AI summary
A catch of a hook bolt comprising the frontal strip with a catch opening for inserting the hook bolt, and a socket to slot the hook bolt in, and a securing element cooperating with the hook bolt characterised in that, the securing element is a slidable strip (5) with the hook opening (6) corresponding to the shape and dimensions of the trunk (8) of the hook bolt (7), slidably mounted on the frontal strip (3) and situated in the area of the catch opening (4) in the frontal strip (3).