Rotational Shaft Locking Mechanism for Model Stability
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Solution Overview
Problem
Existing models with rotatable parts face issues with secure retention of the rotated state due to abrasion between the inner surface of the receiving chamber and the spherical member, leading to reduced friction and stability over repeated rotations.
Innovation Solution
The model employs a rotational shaft portion and a shaft supporting portion with a locking mechanism, where a projecting polygonal portion fits into a recessed polygonal portion, and includes chamfered or rounded corners to ensure secure rotation and automatic disengagement, preventing damage and maintaining stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a spherical member and receiving chamber sliding pair is used for rotation, then the structure is simple, but the retention force reduces due to abrasion over repeated rotations
Solution Approach 1:
The rotation mechanism is segmented into distinct functional components: a rotational shaft portion with locking members, and a shaft supporting portion with corresponding locking members. This segmentation allows the rotation function and retention function to be separated, with the locking members providing positive engagement that maintains retention force without relying on friction between sliding surfaces.
Solution Approach 2:
The locking members are pre-configured on the rotational shaft portion and shaft supporting portion to engage automatically during rotation. This preliminary arrangement ensures that retention is established before wear can occur, eliminating the need for friction-based retention that degrades over time.
2Force
If friction-based retention is used, then the initial retention force is sufficient, but the retention force reduces over time due to wear
Solution Approach 1:
The friction-based mechanical retention system is replaced with a positive locking mechanism using locking members that engage through geometric interlocking. This substitution eliminates wear-related degradation of retention force, as the locking members maintain their engagement capability throughout the service life of the model.
3Productivity
If repeated rotations occur, then the model is reusable, but abrasion reduces stability
Solution Approach 1:
The locking members are designed as simple geometric features (protrusions and recesses) that are inexpensive to manufacture and replace if needed. Their simple geometry allows them to withstand repeated rotation cycles without degradation, maintaining connection stability throughout the model's usable life.
Data Source
AI summary
A model includes arm parts each including a rotational shaft portion, and a body part including a shaft supporting portion and being connected to and rotatable relative to the arm part. The arm part includes a projecting portion. The body part includes a recessed portion into which the projecting portion is fitted when the rotational shaft portion is inserted into the shaft supporting portion. The rotational shaft portion and the shaft supporting portion include respective locking members that are engageable with each other and limit the movement of the rotational shaft portion in an axial direction within a range between a first position where the projecting portion is fitted in the recessed portion and a second position where the projecting portion is out of the recessed portion.