Pivot Assembly Bearing Device Resonance Control
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Solution Overview
Problem
In hard disk drives, the natural frequencies of rolling bearings in pivot assembly bearing devices often coincide, leading to resonance and unstable vibration of swing arms when the drives are operated.
Innovation Solution
The pivot assembly bearing device is designed with two bearing units having different natural frequencies by applying distinct preloads to pairs of rolling bearings, ensuring that the first bearing unit and the second bearing unit have distinct natural frequencies in the axial direction of the shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rolling bearings are provided in multiple bearing units with the same natural frequency, then the structure is simple and easy to manufacture, but resonance occurs causing unstable vibration of swing arms
Solution Approach 1:
The patent applies parameter changes by modifying the natural frequency of rolling bearings in different bearing units through varying preload forces. Specifically, different preload forces are applied to the first and second rolling bearings, which changes their stiffness characteristics and consequently their natural frequencies. This parameter modification prevents resonance between bearing units while maintaining structural simplicity, directly resolving the contradiction between reliability and device complexity
Solution Approach 2:
The patent implements local quality by making each bearing unit have distinct local characteristics through different preload applications. The first bearing unit has a specific natural frequency determined by its preload, while the second bearing unit has a different natural frequency determined by its preload. This local differentiation prevents system-wide resonance while keeping the overall structure simple, addressing the contradiction between stability and complexity
2Reliability
If different preloads are applied to rolling bearings in different bearing units, then resonance is reduced and swing stability is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent uses parameter changes to differentiate the preload forces applied to rolling bearings in different bearing units. By controlling the preload parameter (applying different magnitudes to first and second rolling bearings), the natural frequencies are adjusted to avoid resonance. This parameter-based approach maintains manufacturing feasibility while achieving the desired stability improvement
Solution Approach 2:
The patent applies preliminary action by pre-setting different preload forces during the assembly process. The preload conditions are established in advance during manufacturing, which simplifies the overall process compared to attempting to adjust natural frequencies after assembly. This preliminary differentiation of preload parameters achieves both manufacturing ease and resonance prevention
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 design effectively reduces resonance-induced vibrations, allowing the swing arms to swing more stably and reducing the likelihood of resonance between the bearing units.
Implementation Method 1
a pair of first rolling bearings provided in the axial direction of the shaft and each including a first inner ring fitted on the shaft, a first outer ring provided on an outer side of the first inner ring, and a plurality of first rolling elements that are provided between the first outer ring and the first inner ring
Data Source
AI summary
A technique for swinging swing arms stably by reducing vibrations of bearing units due to resonance in rolling bearings is provided. A pivot assembly bearing device 1 includes a shaft 10 extending in an axis Y1 direction, and an upper bearing unit 20 and a lower bearing unit 60 that are provided along the axis Y1 direction of the shaft 10. A natural frequency of the upper bearing unit 20 and a natural frequency of the lower bearing unit 60 in the axis Y1 direction of the shaft 10 differ from each other.