Offset Swage Hub Hole Reduces Disk Drive Suspension Distortion
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Solution Overview
Problem
Existing disk drive suspensions are sensitive to irregularities in the swage hub dimensions and swaging process, leading to undesirable variations in the position of the transducer head relative to the recording medium platter, particularly in pitch static attitude (PSA) and roll static attitude (RSA).
Innovation Solution
The inside diameter (ID) of the swage hub is offset relative to the outside diameter (OD), with the thinner side positioned away from the head slider, creating a differential deformation direction that reduces post-swaging distortion and variability by deforming more towards the proximal end, thereby minimizing PSA and RSA variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional circular swage hub is used, then manufacturing is simple and rework is easier, but post-swaging distortion and variability in PSA and RSA increase
Solution Approach 1:
The patent applies asymmetry by offsetting the inside diameter (ID) of the swage hub relative to its outside diameter (OD), creating a non-uniform wall thickness distribution. Specifically, the ID is offset toward the proximal end of the base plate, making the swage hub wall thinner on the proximal side. This asymmetric geometry deliberately introduces controlled deformation during swaging to compensate for and reduce post-swaging distortion in the suspension arm, thereby improving PSA and RSA precision without requiring complex non-circular hub shapes.
2Reliability
If the swage hub wall is made uniformly thick, then manufacturing is simpler, but retention torque and swaging stability decrease
Solution Approach 1:
The patent applies local quality by creating a non-uniform wall thickness distribution in the swage hub. The proximal side of the swage hub (away from the head slider) has a thinner wall due to the ID offset, while the distal side maintains greater thickness. This localized variation in wall thickness provides two benefits: (1) The thinner proximal side allows greater deformation during swaging, enhancing retention torque and securing the suspension base plate to the actuator arm; (2) The controlled local deformation reduces post-swaging distortion and variability in the suspension arm's static attitudes.
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 offset design reduces post-swaging distortion and variability in the suspension arm, enhancing retention torque and securing the suspension base plate to the actuator arm, while allowing for easier manufacturing and rework by maintaining round diameters for traditional swage bosses.
Implementation Method 1
the swage hub wall is thinner on the proximal side away from the head slider. Offsetting the ID of the hub flange, i.e., the ID of the hub hole, usually by a few microns, helps to dictate the location of the variation and reduce variability. By making the thinner side of the swage hub wall to be the proximal end which is away from the end on which the head slider is mounted, a differential deformation direction is established by which the proximal side deforms more upon swaging than does the distal side.
Implementation Method 2
The suspension is typically affixed to an actuator arm by swaging, the actuator arm being carried on an E-block which carries a number of actuator arms each having their own associated suspensions affixed thereto. The swage hub 22 is inserted through swage hole 15 in actuator arm 14, and a swage ball (not shown) is then passed through swage hub 22 in order to securely swage suspension 10 to actuator arm 14.
Data Source
AI summary
A base plate for a suspension has a swage hub whose inner diameter is offset from the outer diameter, and more specifically, the inner diameter of the swage hub is offset so as to be farther away from the head slider than is the outer diameter. The offset reduces variability in post-swaging deflection of the suspension at the distal end of the base plate to which the load beam is mounted.