Folding Ruler Snap Joints Hide Axes
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Solution Overview
Problem
Folding rules have manufacturing complexities and visibility issues due to external axes and connecting means, requiring space and complicating the attachment of scales, and existing plastic variants require additional features for locking.
Innovation Solution
A folding rule with links connected via snap connections formed by recesses and axles, where the axle has a front section with a radial projection and a middle section that contacts elastic elements, allowing for secure rotation without external visible axes, simplifying manufacturing and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional joints with axes and elevations/depressions are used to connect links, then reliable locking in folded and unfolded positions is achieved, but the device becomes more complex and requires more manufacturing steps
Solution Approach 1:
The patent combines the axis and the locking mechanism into a single integrated joint structure. The joint element includes an axis portion for rotation and an elevation portion that forms the locking protrusion, eliminating the need for separate locking components. This merging reduces structural complexity while maintaining reliable locking through the interaction between the elevation and depression features.
Solution Approach 2:
The joint element serves multiple functions simultaneously: it provides the rotation axis, creates the locking protrusion (elevation), and works with the depression on the adjacent link. This multi-functional design eliminates the need for separate locking mechanisms, reducing the number of parts and manufacturing steps while ensuring reliable position locking.
2Ease of operation
If a continuous axis extends through both links to enable rotation, then smooth rotational movement is achieved, but the axis becomes visible from the outside and limits space for attaching scales or advertising
Solution Approach 1:
The patent extracts the visible continuous axis from the design and replaces it with discrete joint elements where the axis is contained within compact joints at each link connection point. This extraction eliminates the visual prominence and space occupation of a continuous axis while maintaining rotational functionality through the joint's internal axis portion.
Solution Approach 2:
The axis is nested within the joint element structure rather than extending externally. The axis portion is contained inside the joint, with the elevation portion extending outward for locking functionality. This nesting conceals the axis and maximizes the available surface area on the links for scales or advertising while preserving smooth rotation.
3Area of stationary object
If special connecting means are used to create rotatability without a continuous axis, then space is saved and connections can be hidden, but the manufacturing process becomes more complex due to additional metal connecting components
Solution Approach 1:
The patent uses homogeneous plastic material for the entire joint element, eliminating the need for separate metal connecting components. The joint element can be manufactured as a single molded part or integrated component, simplifying the manufacturing process while achieving the same space-saving and concealment benefits of discrete connecting means.
Solution Approach 2:
The joint element utilizes plastic material that combines the functions of the axis, locking mechanism, and connecting element into a single material system. This composite approach replaces traditional metal-plastic assemblies, reducing manufacturing complexity while maintaining the compact, hidden connection design that preserves surface area.
4Reliability
If elevations and depressions are provided on both sides of the axis for locking, then secure positioning in folded and unfolded states is achieved, but a relatively large amount of space is required around the joint
Solution Approach 1:
The elevation and depression features are merged into a compact joint structure where the elevation on one link and the depression on the adjacent link interlock in a space-efficient manner. This integration minimizes the volume required for the locking mechanism while ensuring secure positioning through the complementary elevation-depression interaction.
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
The solution provides a cost-effective and simpler manufacturing process while maintaining secure link connections, hiding the joint from view and allowing for stable rotational positions without external axis visibility, enhancing usability and aesthetics.
Implementation Method 1
the opening of which is delimited by at least one elastic element
Implementation Method 2
The middle portion is in contact with the elastic member when the axle is received in the recess
Data Source
Figure 1~2b
Figure 3~5
AI summary
The ruler has several joint elements (11,13) which are interconnected at their ends. The recess (21) of joint element (11) and axis (41) of front portion are snap-connected to hold joint elements together. The axis of front portion is arranged adjoining central portion (47) which is in contact with elastic element (31), when axis is received by recess. The contact surface (49) of central portion is in contact with elastic element. The distance of side of the contact surface along the axis extending transition region (51) to the center axis is greater than that of the contact surface.