Locking Bar Fitting Anti-Levering Strip for Window Frames
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Solution Overview
Problem
Existing locking bar fittings for windows and doors can be vulnerable to unauthorized opening through levering, as the locking elements can be released using tools like screwdrivers, compromising burglary protection and aesthetics due to bulky frame configurations required for enhanced security.
Innovation Solution
A dimensionally stable metal strip with increased flexural rigidity, featuring longitudinal webs and an extruded profile, is indirectly connected to the frame member, covering locking elements and bars, making it impossible to bend open using tools, and can be retrofitted with self-tapping screws and an undercut groove for easy assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the locking bar fitting is directly connected to the frame member using only form-fitting engagement, then the assembly is simple and easy to install, but the locking elements are vulnerable to unauthorized opening through levering with tools
Solution Approach 1:
A dimensionally stable strip is introduced as an intermediary element between the locking bar fitting and the frame member. This strip serves as a mediator that provides both mechanical reinforcement against levering attacks and a stable mounting surface for screw connections, thereby enhancing burglary protection without requiring direct complex integration into the frame member structure.
Solution Approach 2:
The solution combines different connection methods (form-fitting engagement and screw fixation) on the same strip structure. The strip itself can be made from dimensionally stable materials that resist deformation, creating a composite connection system that leverages both mechanical engagement and threaded fastening to achieve high reliability against burglary attempts.
2Reliability
If separate grooves are arranged next to one another for locking element and locking bar, then burglary protection is improved, but the frame spar becomes bulky and does not meet visual requirements
Solution Approach 1:
Instead of arranging grooves side-by-side in the horizontal dimension which increases frame width, the invention uses a single groove for form-fitting engagement while adding screw fixation in the vertical dimension through the strip. This dimensional transition allows burglary protection to be achieved without increasing the frame spar width, maintaining aesthetic requirements.
3Reliability
If the locking bar fitting is securely connected to prevent levering, then burglary protection is enhanced, but retrofitting becomes more difficult
Solution Approach 1:
The anti-levering reinforcement is segmented into a separate removable strip that can be independently installed and removed. This segmentation allows the strip to be fitted onto existing frame members with standard grooves, enabling retrofitting without modifying the original frame structure or locking mechanism, thus maintaining ease of installation while enhancing security.
Data Source
Figure 1
Figure 2
Figure 3a
AI summary
An arrangement of a locking bar fitting (2) on a frame member (1) of a sash frame of a window or door, wherein the locking bar fitting (2) has at least one locking bar (3) held on the frame member (1) and at least one locking element (4) with a locking pin (5) attached thereto, wherein at least one strip (7) at least partially covering at least a part of the locking bar fitting (2) is firmly connected to the frame member (1).