Tolerance Ring Overlapping Tabs Mass Eccentricity
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Solution Overview
Problem
State-of-the-art tolerance rings in disc drives suffer from mass imbalance and mass eccentricity issues due to manufacturing gaps, which affect the alignment and performance of actuator arms, necessitating manual alignment or added eccentric mass to compensate.
Innovation Solution
A tolerance ring design with radially displaced or overlapping tabs eliminates the circumferential gap between tabs, reducing mass imbalance and eccentricity by maintaining a radial gap or overlap, thereby improving alignment and installation precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional tolerance ring with circumferential gap is used, then manufacturing is simpler, but mass imbalance and mass eccentricity occur affecting actuator arm alignment
Solution Approach 1:
The tolerance ring is segmented into multiple tabs (first tab and second tab) positioned at specific locations around the circumferential gap. This segmentation allows the gap to be strategically placed in non-critical areas while maintaining mass balance in critical areas, resolving the contradiction between manufacturing simplicity and mass balance precision.
Solution Approach 2:
The tolerance ring employs an asymmetric tab configuration where the first and second tabs are positioned at different circumferential locations rather than symmetrically. This asymmetric arrangement allows the circumferential gap to be located in a non-critical region, eliminating mass imbalance issues while maintaining manufacturing simplicity.
2Manufacturing precision
If tabs are positioned close together to eliminate gap, then mass balance improves, but manufacturing precision becomes more difficult
Solution Approach 1:
The circumferential gap is extracted and relocated to a non-critical region of the tolerance ring, away from the mass balance critical areas. This allows the tabs to be positioned at optimal locations for mass balance without requiring high-precision manufacturing, as the gap is placed where it does not affect rotational balance.
3Reliability
If radial preload compression is applied, then frictional engagement prevents slippage, but installation force increases
Solution Approach 1:
The tolerance ring incorporates elastic deformation capability in the tabs, allowing them to dynamically adjust during installation. The tabs can elastically deform to accommodate the radial preload compression, providing frictional engagement for preventing slippage while reducing the peak installation force required through elastic energy storage and release.
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 design enhances the mass balance and alignment of actuator arms, simplifying installation and reducing performance degradation caused by mass imbalance, while maintaining frictional engagement for secure part retention.
Implementation Method 1
The tolerance ring also acts as a radial spring. In this way, the tolerance ring positions the interior cylindrical part relative to the exterior cylindrical part while making up for radii clearance and manufacturing variations in the radius of the parts.
Data Source
AI summary
A tolerance ring for coupling an actuator arm to a pivot bearing while maintaining mass eccentricity of the actuator arm. The tolerance ring having a substantially cylindrical base portion with a first radius about a central axis and extending a length parallel to the central axis, the cylindrical base portion has a first tab and a second tab extending along the length of the cylindrical base portion, the first tab being positioned proximate to the second tab. The tolerance ring improves mass eccentricity by radially displacing the first tab at a second radius about the axis such that a radial gap is formed between the first tab and second tab.