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, affecting the alignment and performance of actuator arms, which current methods attempt to mitigate through manual alignment or adding eccentric mass, but these solutions are inefficient.

Innovation Solution

A tolerance ring design featuring a cylindrical base with radially displaced or overlapping tabs to eliminate the circumferential gap between tabs, reducing mass imbalance and eccentricity by maintaining a consistent radial preload and improving installation precision.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional tolerance rings with circumferential gaps are used, then manufacturing is simpler, but mass imbalance and mass eccentricity increase

Engineering Contradiction:
Improvemass balance precisionVSAvoidmanufacturing complexity
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The tolerance ring is segmented into multiple tabs (typically 3-5 tabs) distributed around the circumferential direction. Each tab is independently formed and positioned, allowing the gaps between tabs to be strategically designed and controlled. This segmentation enables mass balancing by distributing material non-uniformly while maintaining functional integrity of the tolerance ring.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the tolerance ring have different material distributions. The tabs are designed with specific radial positions, thicknesses, and spacing to create local mass variations that compensate for overall mass imbalance. This local quality approach allows precise control of mass eccentricity while maintaining structural functionality.

Inventive Principle:
Principle #3Local quality

2Manufacturing precision

If manual alignment methods are used to compensate for mass imbalance, then alignment precision can be improved, but installation time and complexity increase

Engineering Contradiction:
Improvealignment precisionVSAvoidinstallation time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The mass balancing features (tabs with specific geometries and positions) are pre-formed during the tolerance ring manufacturing process. This preliminary action embeds the mass balance correction directly into the component design, eliminating the need for time-consuming manual alignment operations during assembly. The tabs are precisely positioned in advance to achieve the desired mass distribution.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The tolerance ring design incorporates self-balancing features where the tabs automatically provide mass compensation without requiring external adjustment or alignment procedures. The structural geometry of the tabs themselves serves the dual function of mechanical retention and mass balancing, making the system self-sufficient.

Inventive Principle:
Principle #25Self-service

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 effectively reduces mass imbalance and eccentricity, enhancing the alignment and performance of actuator arms by eliminating the gap between tabs, thereby improving the overall stability and installation consistency of disc drive components.

Implementation Method 1

The radial preload compression provides frictional engagement that prevents actual slippage of the mating parts

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

The radial preload compression provides frictional engagement that prevents actual slippage of the mating parts

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP2218070B1Tolerance ring for data storage with overlapping tab feature for mass control
Publication Date: 2012.06.06 INTRI PLEX TECHNOLOGIES INC
  • EP2218070B1 patent drawingFigure 1
  • EP2218070B1 patent drawingFigure 2
  • EP2218070B1 patent drawingFigure 3

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.