Articulating Support Arm Friction Joint Non-Annular Bushing
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Solution Overview
Problem
Existing articulating arm and tilter designs face issues with uneven clamping forces and misalignment of bushings, leading to malfunction and loose set screws over time, due to the use of annular bushings and direct set screw pressure.
Innovation Solution
The design incorporates a bushing with a non-circular shape and a split, where the set screw applies force to tabs outside the main circumference, maintaining alignment and providing adjustable friction through a threaded member, ensuring even force distribution and preventing misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a set screw is driven directly into a circular bushing to supply pressure to the rotating cylinder, then friction force is applied to restrict rotation, but the bushing may become misaligned with the gap aligned with the set screw axis causing malfunction
Solution Approach 1:
The bushing is designed with a non-circular cross-section (e.g., rectangular or oval) instead of circular, creating an asymmetric shape that prevents rotational misalignment. The set screw applies pressure to a specific portion of the bushing's outer circumference, and the asymmetric geometry ensures the gap remains properly positioned relative to the set screw axis, eliminating the malfunction issue while maintaining friction-based rotation restriction.
Solution Approach 2:
The bushing is pre-formed with a specific non-circular geometry and a predetermined gap position before assembly. This preliminary shaping ensures that when the set screw is installed, the bushing is already configured to distribute pressure evenly and maintain proper alignment, preventing misalignment issues before they can occur during operation.
2Device complexity
If the bushing clamps around only a small portion of the rotating cylinder width, then the structure is simpler, but clamping forces are unevenly applied and set screws work loose over time
Solution Approach 1:
The bushing applies clamping force at multiple localized contact points around its circumference rather than uniformly across the entire width. The non-circular cross-section creates specific high-contact-area zones that concentrate friction force where needed, ensuring even distribution of clamping forces across the rotating cylinder surface while maintaining structural simplicity.
Solution Approach 2:
The bushing design transitions from a simple circular cross-section to a non-circular cross-section with extended radial elements or tabs that wrap around a larger portion of the rotating cylinder. This dimensional change allows the bushing to engage more extensively with the cylinder surface, distributing clamping forces more evenly across the width while preventing set screw loosening through improved friction distribution.
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 solution enhances the stability and reliability of the articulating arm by maintaining proper bushing orientation and adjusting friction accurately, preventing malfunctions and loose connections, while allowing for greater weight support and quieter operation.
Implementation Method 1
the bushing is configured to contact the rotating cylinder... the threaded member is configured to apply a friction force to the rotating cylinder when the threaded member is rotated into the opening
Data Source
AI summary
The present application discloses an articulating support arm with one or more improved friction joint designs that use a non-annular bushing. In particular, the bushing is designed to interact with another portion of the friction joint to prevent rotational movement of the bushing, thereby minimizing the risk of joint malfunction. A bushing that interacts with a larger percentage of the width of a friction cylinder as compared to prior art devices, thereby improving the performance of the joint, is also disclosed. The improved friction joint according to the present invention may comprise an arm joint and/or tilter joint.