HDD Head Suspension Damper for Torsional Vibration Control
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Solution Overview
Problem
The existing head suspension assemblies in hard disk drives (HDDs) face challenges with torsional vibration resonance due to low resonance frequencies of the load beam, which affects magnetic head positioning accuracy, and the attenuation of this vibration is difficult to maintain across a wide temperature range due to varying damper characteristics.
Innovation Solution
A head suspension assembly is designed with a damper comprising a viscoelastic layer and a constraint layer stacked on the support plate, covering the joined portions of the load beam and flexure, utilizing viscoelastic materials with different temperature-specific damping characteristics to effectively suppress torsional vibration across a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If piezoelectric elements are mounted on the flexure to enable precise head positioning, then positioning accuracy is improved, but torsional vibration resonance occurs on the load beam due to the low resonance frequency
Solution Approach 1:
A damper is introduced as an intermediary component between the load beam and the magnetic head assembly. The damper includes a viscoelastic layer and a constraint layer that work together to absorb and dissipate the torsional vibration energy generated by the piezoelectric elements, preventing resonance on the load beam while allowing the positioning function to remain effective.
Solution Approach 2:
The damper's viscoelastic layer is designed with specific material properties and geometric parameters (thickness, area, position) that can be adjusted to change the damping characteristics. By optimizing these parameters, the damper effectively suppresses torsional vibration at the load beam's resonance frequency without interfering with the piezoelectric positioning mechanism.
2Reliability
If a single damper material is used to attenuate torsional vibration, then vibration suppression is achieved at a specific temperature, but the attenuation characteristic varies with temperature and cannot maintain effectiveness across a wide temperature range
Solution Approach 1:
The damper employs a composite structure consisting of a viscoelastic layer and a constraint layer. The viscoelastic layer provides temperature-dependent damping characteristics, while the constraint layer (with higher stiffness) reinforces the structure and modifies the overall damping behavior. This composite configuration enables the damper to maintain effective vibration attenuation across a wide temperature range by combining the complementary properties of the two materials.
Solution Approach 2:
Different regions of the damper have different material properties and structural characteristics. The viscoelastic layer is positioned to maximize damping at critical vibration modes, while the constraint layer is configured to provide structural support and modify damping characteristics at different temperatures. This spatial differentiation of material qualities allows the damper to adapt to varying temperature conditions.
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 effectively attenuates torsional vibration over a broad temperature range, improving the accuracy of magnetic head positioning by optimizing damping characteristics at both low and high temperatures.
Implementation Method 1
The piezoelectric elements move up and down in the thickness direction of the flexure when they expands and contracts
Implementation Method 2
a damper including a viscoelastic layer and a constraint layer stacked on the viscoelastic layer
Data Source
AI summary
According to one embodiment, a head suspension assembly includes a support plate having a proximal end and a distal end, a wiring member on the support plate and including a metal plate and a wiring board laid on the metal plate, the metal plate including a first joined portion joined to the support plate close to the distal end and a second joined portion joined to the support plate and located on a proximal end side of the support plate, a head mounted on the wiring member, an extendable piezoelectric element mounted on the wiring member, and a damper including a viscoelastic layer and a constraint layer stacked on the viscoelastic layer and attached to the support plate to cover the first joined portion and the second joined portion.