Stepped Assembly Tolerance Ring for Hard Disk Drive Stability
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Solution Overview
Problem
The assembly of hard disk drives using tolerance rings often results in abrasion and particle generation, as well as torque ripple due to axial misalignment, which can lead to premature failure and functional issues.
Innovation Solution
A stepped assembly design is implemented, where the outer and inner components have stepped sidewalls and a tolerance ring with radially extending projections, allowing for reduced particle generation and improved concentricity by balancing radial forces and facilitating smoother assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If tolerance rings are used in hard disk drive assembly, then assembly is facilitated, but particle generation occurs due to abrasion between the tolerance ring and apparatus parts
Solution Approach 1:
The tolerance ring is segmented into multiple radially extending projections rather than a continuous ring. This segmentation reduces the contact area between the tolerance ring and the actuator arm, minimizing abrasion and particle generation while still providing the necessary assembly facilitation through the distributed projections
Solution Approach 2:
The tolerance ring features localized radially extending projections at specific positions rather than a uniform continuous structure. This local quality approach concentrates the assembly facilitation function at discrete points while reducing overall friction and particle generation areas
2Strength
If tolerance rings are used in hard disk drive assembly, then components can be joined, but torque ripple occurs due to axial misalignment from press fitting forces
Solution Approach 1:
The tolerance ring is divided into multiple radially extending projections that distribute the press fitting forces across multiple contact points. This segmentation prevents concentrated forces that cause axial misalignment and torque ripple, while still achieving secure component joining through the distributed engagement
Solution Approach 2:
The radially extending projections are positioned asymmetrically or at specific angular intervals rather than uniformly distributed. This asymmetric configuration balances the radial forces during assembly, preventing axial misalignment and torque ripple while maintaining effective component joining
3Ease of operation
If radially outermost parts of tolerance ring projections slide relative to apparatus parts, then assembly is achieved, but particle generation increases at these sliding surfaces
Solution Approach 1:
The harmful radially outermost parts of the projections are removed or truncated to create chamfered or rounded edges. This extraction of the problematic sliding surfaces reduces abrasion and particle generation while maintaining the essential assembly function through the remaining projection structures
Solution Approach 2:
The projections are pre-formed with chamfered or rounded leading edges before assembly. This preliminary action prepares the contact surfaces to reduce friction and particle generation during the sliding assembly process, achieving ease of operation without the harmful effects
Data Source
AI summary
A tolerance ring can be disposed between an inner component and an outer component, the inner and outer components defining stepped sidewalls. In an embodiment, a preassembly can include an outer component defining a bore having a stepped inner sidewall, an inner component having a stepped outer sidewall, and a tolerance ring adapted to be disposed between the inner component and the bore. In an embodiment, an assembly can include an outer component defining a bore having a stepped inner sidewall, an inner component having a stepped outer sidewall, and a tolerance ring disposed between the inner component and the bore. In an embodiment, a hard disk drive preassembly can include an actuator arm defining a bore having a stepped inner sidewall, a pivot having a stepped outer sidewall, and a tolerance ring adapted to be disposed between the pivot and the bore.