Scissor Extendable Arm Geometry for Higher Rigidity
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Solution Overview
Problem
Extendable arms used in applications like partitions and furniture lack sufficient rigidity when in an extended state, which affects their structural integrity and functionality.
Innovation Solution
The design incorporates a plurality of X-shaped cross units pivotally coupled with middle and end coupling shafts, where each rigid member has specific surface and strip configurations that enhance rigidity by ensuring perpendicular alignment of middle strip regions to base surfaces, thereby increasing stability against vertical loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If extendable arms are designed to be compact for easy carrying and storage, then portability is improved, but rigidity in extended state deteriorates
Solution Approach 1:
The extendable arm is divided into multiple cross units, each comprising two rigid members connected by coupling shafts. This segmentation allows the structure to be compact when contracted for portability while maintaining rigidity when extended through the coordinated arrangement of multiple segments
Solution Approach 2:
The rigid members are configured with specific three-dimensional geometries including strip-shaped portions and perpendicular arrangements. The middle strip regions are positioned perpendicular to the bottom-side outer side surfaces, creating a spatial configuration that provides rigidity in the extended state while allowing compact contraction
2Adaptability or versatility
If multiple cross units are pivotally coupled to form an extendable arm, then extendability is improved, but structural stability deteriorates
Solution Approach 1:
The cross units feature asymmetric configurations where the middle strip regions are positioned perpendicular to the bottom-side outer side surfaces, and tip-end projecting strip portions extend from specific ends. This asymmetric arrangement creates inherent structural stability that prevents unwanted movement while allowing controlled extension and contraction
Solution Approach 2:
The rigid members are pre-configured with specific geometries including perpendicular middle strip regions and tip-end projecting portions that abut on inner side surfaces of adjacent cross units. This preliminary structural arrangement ensures stability is built into the design, preventing structural degradation during extension operations
Data Source
AI summary
An extendable arm includes first and second rigid members forming a cross unit. Each rigid member includes one end portion including one of end coupling shafts, the other end portion including the other end coupling shaft, and a middle portion including a middle coupling shaft. The one end portion of each rigid member includes a bottom-side outer side surface that surface-contacts a base surface when the extendable arm in an extended state is placed thereon. The other end portion of each rigid member includes a top-side outer side surface extending parallel to the bottom-side outer side surface of each rigid member. The middle portion of each rigid member includes a middle strip region passing through a middle coupling shaft and perpendicular to the bottom-side outer side surface and the top-side outer side surface.