Non-Circular Boss Tower for Actuator Arm Stability
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Solution Overview
Problem
The swaging process in hard disk drive systems often results in distortion and bending of the actuator arm due to circular engagement surfaces, leading to suboptimal quality of the head stack assembly.
Innovation Solution
The use of non-circular engagement surfaces, such as oval or elliptical shapes, for the boss tower outer surface, swage hole, or actuator arm aperture, which produces unequal compression forces in the pitch and roll directions, reducing distortion and improving the assembly's quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If circular engagement surfaces are used for the boss tower and actuator arm aperture, then the swaging process creates uniform compression, but it causes distortion and bending of the actuator arm
Solution Approach 1:
The patent applies asymmetry by changing the circular engagement surfaces to non-circular shapes (oval, elliptical, or other irregular shapes). This asymmetric geometry causes the compression forces during swaging to be distributed unevenly, which counteracts the distortion and bending that occur with circular surfaces. The non-circular shape creates unequal compression in different directions, thereby stabilizing the actuator arm while maintaining manufacturing precision.
2Ease of manufacture
If circular engagement surfaces are used, then the swaging process is simple and uniform, but it produces unequal compression forces that lead to distortion
Solution Approach 1:
The patent changes the symmetric circular geometry to asymmetric non-circular geometry for the engagement surfaces. This modification creates unequal compression forces during the swaging process, which are specifically designed to counteract the distortion and bending of the actuator arm. The asymmetric shape distributes compression forces more effectively across the engagement interface, improving actuator arm stability while remaining manufacturable.
Solution Approach 2:
The patent applies local quality by creating non-uniform compression distribution through the non-circular engagement surface geometry. Different regions of the engagement surface are designed to experience different compression levels, with areas prone to distortion receiving higher compression to counteract bending. This localized variation in compression forces stabilizes the actuator arm while maintaining overall manufacturing feasibility.
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 non-circular engagement surfaces minimize distortion and bending of the actuator arm, resulting in an improved overall quality of the head stack assembly by distributing compression forces more evenly.
Implementation Method 1
When a swage ball is passed through the boss tower when fitted in the arm aperture, the boss tower expands contacting the aperture surface and creating a frictional engagement
Implementation Method 2
the boss tower expands contacting the aperture surface and creating a frictional engagement that connects the suspension assembly to the actuator arm
Data Source
AI summary
A head stack assembly comprising an actuator arm having an aperture therein, a head suspension assembly comprising a load beam having a mounting region with a aperture therein, and a base plate adapted to attach the head suspension assembly to the actuator arm, with the base plate comprising a boss tower having an outside surface and a swaging hole. One of the actuator arm aperture, the boss tower outside surface or the swaging hole is non-circular to provide increased compression between the boss tower and the actuator arm aperture in the roll direction than in the pitch direction. Methods of making a boss tower are also provided.