Tolerance Ring Asymmetric Protrusion Pattern for Rigidity Uniformity
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Solution Overview
Problem
Conventional tolerance rings exhibit uneven rigidity, leading to instability in the fixation between the carriage and pivot shaft in hard disk devices, due to variations in spring constant across different radial directions.
Innovation Solution
A tolerance ring with a circular shape and radially projected protrusions, arranged in a specific pattern to ensure even distribution of spring constant, and featuring notches and varying radius of curvature to maintain consistent rigidity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If contacting parts are arranged on a straight line passing through the center of the ring (180° apart), then the structure is simple and easy to manufacture, but the rigidity becomes uneven (high at some places, low at others), reducing fixation stability
Solution Approach 1:
The patent applies asymmetry by arranging contacting parts at specific angular positions that are NOT 180° apart. Instead of symmetric opposite placement, the contacting parts are positioned at angles that create crossing straight lines through the center, distributing rigidity more evenly throughout the ring structure while maintaining manufacturing simplicity
Solution Approach 2:
The patent achieves equipotentiality by distributing the contacting parts such that the rigidity becomes more uniform around the ring. By positioning the parts so that straight lines connecting them through the center cross each other, the structural stiffness is equalized at different angular positions, preventing localized weak points
2Adaptability or versatility
If the variation width of spring constant is large, then the contacting parts can accommodate more variation, but the unevenness of rigidity increases, leading to unstable fixation
Solution Approach 1:
The asymmetric angular arrangement of contacting parts prevents the amplification of spring constant variations. By avoiding 180° opposition and using specific angular positions where connecting lines cross, the system distributes the effect of material variations more uniformly, maintaining both adaptability and fixation stability
3Ease of operation
If the tolerance ring uses a conventional design with contacting parts, then the fixation function is achieved, but the uneven rigidity causes instability in the fixation between carriage and pivot shaft
Solution Approach 1:
The patent achieves equipotentiality in the rigidity distribution by strategically positioning contacting parts at angular positions where the straight lines connecting them through the center cross each other. This creates a more uniform stiffness field around the ring, ensuring stable fixation without compromising the ease of operation
Solution Approach 2:
The patent applies local quality by giving different angular positions to the contacting parts based on their specific functional requirements. Each contacting part is positioned at an optimized angle to contribute to overall rigidity uniformity, with the local position determined by the need to create crossing lines through the center
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 effectively suppresses the unevenness of rigidity, enhancing the stability of fixation between the carriage and pivot shaft, ensuring accurate operation and assembly of hard disk devices.
Implementation Method 1
When the protrusion is regarded as a spring, both ends of which are fixed respectively to the central portion of the protrusion and the center of the circumscribed circle
Data Source
AI summary
A tolerance ring is formed of a plate member, in a ring shape that is substantially circular along a predetermined direction, and provided with a plurality of protrusions projected radially in a circumferential direction, wherein an even number of the protrusions are arranged along the circumferential direction, and a plurality of straight lines that pass through a central portion of the plurality of protrusions and a center of a circle that circumscribes the tolerance ring cross one another.