Tolerance Ring Stiffness Variation for Disk Drive Mount Distortion
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Solution Overview
Problem
Conventional tolerance rings in small-scale apparatus like hard disk drive pivot mounts experience uneven compression forces, leading to distortion of components and resonance issues due to the uniform stiffness of projections, which affects the resonant frequency and torque profile.
Innovation Solution
The tolerance ring design varies the stiffness of its projections around the circumference, with stiffer edge projections adjacent to the gap and progressively softer body projections, ensuring even force distribution and minimizing distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform stiffness projections are used in the tolerance ring, then the manufacturing is simpler, but the compression force distribution becomes uneven causing component distortion
Solution Approach 1:
The tolerance ring employs projections with varying stiffness characteristics around its circumference. Edge projections adjacent to the gap have higher stiffness to provide greater compression force, while body projections in the middle have lower stiffness. This local differentiation of projection properties ensures even compression force distribution across the components, preventing distortion while maintaining manufacturing feasibility through a systematic variation pattern.
Solution Approach 2:
The tolerance ring design introduces asymmetry in the projection stiffness distribution. Rather than uniform stiffness throughout, the projections are deliberately designed with different stiffness values at different locations - stiffer at the edges near the gap and softer in the body regions. This asymmetric stiffness profile compensates for the natural tendency of uniform projections to create uneven force distribution, thereby eliminating component distortion.
2Device complexity
If uniform stiffness projections are used in the tolerance ring, then the structure is simpler, but resonance issues occur due to uneven compression forces affecting resonant frequency
Solution Approach 1:
The tolerance ring employs projections with varying stiffness characteristics around its circumference. Edge projections adjacent to the gap have higher stiffness to provide greater compression force, while body projections in the middle have lower stiffness. This local differentiation of projection properties ensures even compression force distribution across the components, preventing distortion while maintaining manufacturing feasibility through a systematic variation pattern.
Solution Approach 2:
The invention changes the physical parameter of projection stiffness around the circumference of the tolerance ring. By systematically varying the stiffness parameter - increasing it at edge projections and decreasing it at body projections - the design achieves uniform compression force distribution. This parameter variation controls the resonant frequency of the assembly by ensuring even force distribution, thereby improving reliability without excessive structural complexity.
3Manufacturing precision
If edge projections have higher stiffness, then the compression force distribution becomes more even, but the projection stiffness variation increases complexity
Solution Approach 1:
The tolerance ring employs projections with varying stiffness characteristics around its circumference. Edge projections adjacent to the gap have higher stiffness to provide greater compression force, while body projections in the middle have lower stiffness. This local differentiation of projection properties ensures even compression force distribution across the components, preventing distortion while maintaining manufacturing feasibility through a systematic variation pattern.
Solution Approach 2:
The tolerance ring projections are segmented into distinct categories based on their stiffness characteristics and locations. Edge projections near the gap are designed with higher stiffness, while body projections in the middle regions have lower stiffness. This segmentation of projections into different stiffness groups allows for systematic control of compression forces, achieving uniform force distribution while managing complexity through a clear segmented design approach.
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
This design achieves controlled compression forces, reducing distortion and providing greater control over the resonant frequency and torque profile in hard disk drive pivot joints.
Implementation Method 1
a tolerance ring comprising a strip of resilient material having a plurality of radially extending projections which are compressible between the inner and outer components
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
An apparatus includes an inner component (42), an outer component (36); and a tolerance ring (20) located between the inner and outer components to provide an interference fit there between. The tolerance ring includes a strip of material having a plurality of radially extending projections (72). The strip of material is curved into a ring having a gap. The radially extending projections are compressible between the inner and outer components, and the stiffness of the radially extending projections varies around the circumference of the tolerance ring.