Folding Ruler Joint Plates for Play-Free Two-Position Locking
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Solution Overview
Problem
Existing folding rules face challenges in ensuring precise and play-free locking of links in multiple positions due to small dimensions and complex structural designs, often requiring precise alignment of locking projections and recesses.
Innovation Solution
The folding rule incorporates joint plates with additional locking recesses and projections, including resilient sections and cut-out areas, allowing for simple and secure locking in two positions without necessitating weakening of the links.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple locking projections and recesses are provided on joint plates to ensure precise locking in multiple positions, then locking reliability is improved, but device complexity increases
Solution Approach 1:
The locking mechanism is segmented into two functional parts: fixed locking projections on one joint plate and corresponding locking recesses on the other joint plate. This segmentation allows each component to have a simple, single-function design while achieving reliable multi-position locking through their interaction.
Solution Approach 2:
Instead of providing multiple locking projections on each joint plate as in prior art, the invention inverts the approach by providing multiple locking recesses on one joint plate and corresponding projections on the other. This inversion simplifies the overall structure while maintaining locking reliability.
2Manufacturing precision
If locking recesses are precisely aligned with locking projections to ensure play-free locking, then locking precision is improved, but manufacturing difficulty increases
Solution Approach 1:
The joint plates are designed with local quality differentiation: one joint plate has fixed locking projections while the other has locking recesses. This local differentiation allows each plate to be manufactured with simpler features, reducing the overall manufacturing precision requirements compared to providing multiple projections and recesses on each plate.
3Adaptability or versatility
If resilient sections with locking projections are added to enable locking in second position, then locking versatility is improved, but device complexity increases
Solution Approach 1:
The resilient section with locking projection is designed to be elastically deformable, allowing it to dynamically adapt during the locking process. The resilient projection can deform to engage with the locking recess and then maintain a stable locked position, providing locking versatility without requiring complex mechanical mechanisms.
Solution Approach 2:
The resilient section utilizes elastic deformation as a key parameter change mechanism. By changing the physical state of the locking projection from rigid to elastically deformable, the system achieves versatile locking capability across multiple positions while keeping the structural design relatively simple.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design ensures reliable locking in two positions, such as fully unfolded or at a 90-degree angle, with minimal play and without requiring additional machining on the links, maintaining structural integrity and ease of assembly.
Implementation Method 1
the at least one further locking projection is formed in a resilient section of the second joint plate or extends therefrom
Data Source
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AI summary
The invention relates to a folding ruler with elongated, flat segments that are rotatably connected to each other and about an axis (124, 224, 324) in pairs via a joint connection, wherein the joint connection comprises a first joint plate (152) connected to a first segment and a second joint plate (152) connected to a second segment. The first joint plate has two detent projections, and the second joint plate has two first detent recesses (158, 160) and two second detent recesses (168, 170). The two first and the two second detent recesses (158, 160; 168, 170) are cutouts in the second joint plate (152) into which the detent projections engage in a first and second position, respectively.