Disk Drive Actuator Taper Lock Shims for Radial Stiffness
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Solution Overview
Problem
Conventional disk drive actuator assemblies face issues such as high cost, poor reworkability, component shifting due to shock events, uneven radial loading, and low radial stiffness, leading to poor dynamic performance and increased pivot friction.
Innovation Solution
A disk drive actuator assembly utilizing tapered shims, where a first tapered shim and a second tapered shim are interposed between the pivot bearing and the actuator arm, with the second shim frictionally engaging the first shim to securely hold the pivot bearing in place, providing improved radial stiffness and reduced pivot friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional attachment methods (press fitting, adhesive bonding, set screws, threaded pivot shafts and nuts, wavy washers, snap rings, tolerance rings/interference bands) are used to attach actuator arms to pivot bearings, then the actuator arm can be held in place, but component shifting occurs due to shock events and radial stiffness is low resulting in poor assembly dynamic performance
Solution Approach 1:
The patent applies parameter changes by transitioning from conventional attachment methods to a taper lock mechanism. The taper angle parameter (typically 1:10 or 1:12) transforms the axial clamping force into radial locking force, significantly increasing radial stiffness. This geometric parameter change enables the actuator arm to resist shock events and prevents component shifting while maintaining high radial stiffness for improved dynamic performance.
Solution Approach 2:
The patent utilizes the taper lock mechanism which employs a conical (curved) interface between the actuator arm and pivot bearing. This curved geometry, defined by the taper angle, converts axial compression into radial clamping force, providing superior component stability and resistance to shock events compared to flat or cylindrical interfaces used in conventional attachment methods.
2Ease of manufacture
If conventional attachment methods are used, then assembly can be completed, but uneven radial loading results in uneven pivot friction and seek/settle issues
Solution Approach 1:
The taper lock mechanism changes the loading parameter distribution through its geometric configuration. The taper angle ensures that the clamping force is uniformly distributed around the pivot bearing circumference, eliminating uneven radial loading. This uniform force distribution results in consistent pivot friction characteristics and resolves seek/settle issues that plague conventional attachment methods.
3Reliability
If conventional attachment methods are used, then the actuator arm can be attached to the pivot bearing, but the cost of components and assembly is high
Solution Approach 1:
The taper lock mechanism merges multiple functions into a single integrated component. The actuator arm itself incorporates the taper lock features, eliminating the need for separate attachment components such as set screws, nuts, or interference bands. This consolidation reduces component count, lowers manufacturing costs, and simplifies assembly while maintaining high attachment reliability and preventing component shifting under shock events.
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 solution enhances radial stiffness, reduces sensitivity to radial clearance variations, and minimizes pivot friction, resulting in improved assembly performance and cost-effectiveness.
Implementation Method 1
the second tapered shim frictionally engages the first tapered shim to hold the pivot bearing substantially in place relative to the actuator arm
Data Source
AI summary
Various methods and apparatus relating to disk drive actuators and methods of manufacturing them are disclosed and claimed. In certain embodiments, a disk drive actuator assembly comprises a pivot bearing defining a pivot bearing rotational axis; an actuator arm including a bore, the pivot bearing disposed at least partially within the bore; a first tapered shim, interposed in the bore between the pivot bearing and the actuator arm, the first tapered shim having a thickness at a first end greater than a thickness at a second end; and a second tapered shim, interposed in the bore between the pivot bearing and the actuator arm, the second tapered shim having a thickness at a third end greater than a thickness at a fourth end; wherein the second tapered shim frictionally engages the first tapered shim to hold the pivot bearing substantially in place relative to the actuator arm.