Tolerance Ring Cut-Out Mass Control for HDD Actuator Balance
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Solution Overview
Problem
State-of-the-art tolerance rings in hard disk drives suffer from mass imbalance and eccentricity issues due to manufacturing gaps, leading to dynamic balance problems and performance reduction, which are currently compensated for by manual alignment or balancing nearby parts, but these methods are inefficient and do not fully address the issue.
Innovation Solution
A tolerance ring design featuring hook-shaped tabs and cut-out features that engage to close the manufacturing gap, reducing mass imbalance and eccentricity by distributing mass evenly, and preventing interlocking during shipping and handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a tolerance ring is manufactured with a gap to accommodate manufacturing tolerances, then ease of manufacture is improved, but mass balance and dynamic balance deteriorate due to mass imbalance and eccentricity
Solution Approach 1:
The patent extracts the harmful gap from the tolerance ring structure by adding tabs that engage with each other to close the gap. The tabs are designed to eliminate the space between ring ends while maintaining the manufacturing flexibility of the gap design. This resolves the contradiction by removing the negative effect (mass imbalance) while preserving the positive effect (ease of manufacture).
Solution Approach 2:
The patent introduces asymmetric tab features at specific locations on the ring to counterbalance the mass imbalance caused by the gap. The tabs are strategically positioned and sized to create counterbalancing mass distribution, allowing the ring to maintain both manufacturing ease and dynamic balance. This asymmetric modification resolves the contradiction by adding targeted mass compensation.
2Manufacturing precision
If manual alignment or balancing of nearby parts is used to compensate for mass imbalance, then mass balance can be improved, but device complexity and manufacturing time increase
Solution Approach 1:
The tolerance ring with tabs is designed to self-balance through its inherent geometric features. The tabs automatically position themselves during assembly to achieve proper mass balance without requiring external alignment tools or manual adjustment procedures. This eliminates the need for complex manual balancing operations while maintaining high mass balance precision.
Solution Approach 2:
The mass balance features are built into the tolerance ring design during manufacturing, before assembly. The tabs are pre-positioned and pre-configured to provide automatic mass compensation, eliminating the need for post-assembly balancing operations. This preliminary incorporation of balancing features reduces both device complexity and manufacturing time.
3Manufacturing precision
If tabs are added to close the gap, then mass balance is improved, but the risk of interlocking during shipping increases
Solution Approach 1:
The tabs are designed to provide just enough engagement to close the gap and achieve mass balance, but not so much engagement that they cause interlocking during shipping. The tab geometry is optimized to provide partial closure - sufficient to eliminate mass imbalance but limited to prevent excessive engagement that would create handling problems. This resolves the contradiction by applying the right amount of action.
Solution Approach 2:
The gap closure function is segmented into discrete tab features rather than a continuous engagement structure. The tabs are separated by spacing that prevents them from interlocking during shipping, while still providing sufficient engagement to close the gap for mass balance. This segmentation allows the structure to maintain both mass balance and handling freedom.
Data Source
AI summary
A tolerance ring configured to improve mass eccentricity of an actuator arm assembly. The tolerance ring has a cylinder with a predetermined length between two ends, with a gap along the predetermined length of the cylinder, the gap having a first and a second edge, the cylinder having an aperture in the surface of the cylinder at the second edge.