Discrete-Panel Tolerance Ring for Uniform Stiffness and Alignment
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Solution Overview
Problem
Tolerance rings used in hard disk drives exhibit performance variability due to uneven stiffness, which affects resonance and alignment, and optimizing one parameter can compromise others, leading to compromised overall performance.
Innovation Solution
A tolerance ring design featuring discrete panels equally spaced around the circumference, providing consistent resonant frequency and stiffness, and preventing rocking of the pivot assembly within the bore under normal operational loads by maintaining alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a tolerance ring is designed with continuous protrusions or formations, then torque transmission capability is improved, but stiffness uniformity deteriorates leading to performance variability
Solution Approach 1:
The tolerance ring is divided into discrete panels separated by gaps, with each panel containing protrusions. This segmentation creates multiple independent stiffness zones that collectively provide uniform overall stiffness while maintaining torque transmission capability through the distributed protrusions across multiple panels.
2Manufacturing precision
If protrusions are made more numerous or larger to improve interference fit, then alignment precision is improved, but manufacturing complexity increases
Solution Approach 1:
The tolerance ring is segmented into multiple discrete panels, each containing a limited number of protrusions. This segmentation allows each panel to be manufactured with standard precision, avoiding the need to manufacture entire rings with extremely tight tolerances, thereby reducing overall manufacturing complexity while achieving precise alignment through the cumulative effect of multiple panels.
3Stability of the object's composition
If the tolerance ring is made more rigid to prevent rocking, then alignment stability is improved, but adaptability to dimensional variations deteriorates
Solution Approach 1:
The discrete panel structure with gaps allows the tolerance ring to dynamically adapt to dimensional variations in the shaft and bore. The gaps provide compliance that accommodates manufacturing tolerances, while the protrusions on each panel provide localized rigid contact points that prevent rocking and maintain alignment stability under operational loads.
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 ensures consistent axial stiffness and resonant frequency around the tolerance ring, preventing rocking and maintaining alignment, thereby enhancing the reliability and performance of hard disk drive assemblies.
Implementation Method 1
A tolerance ring generally comprises a strip of resilient material, for example a metal such as spring steel, the ends of which are brought together to form a ring. A band of protrusions extend radially outwards from the ring... Each protrusion acts as a spring and exerts a radial force against the shaft and the surface of the bore, providing an interference fit
Data Source
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AI summary
A tolerance ring for a hard disc drive assembly is disclosed and can include a plurality of discrete tolerance ring panels. Each tolerance ring panel can include an arcuate sidewall that can include an unformed portion and at least one projection extending from the arcuate sidewall. The projection can be surrounded by the unformed portion of the arcuate sidewall and the tolerance ring can be configured to be deployed in an interference fit between an inner component and an outer component to provide torque coupling between an inner component and an outer component.