Actuator Plate Constriction for Disk Drive Positioning Accuracy
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Solution Overview
Problem
Magnetic disk devices with a reduced number of suspensions face challenges in maintaining positioning accuracy and frequency characteristics due to the higher rigidity of conventional plates used in place of suspensions, leading to variations in actuator frequency and difficulty in securing equal positioning accuracy compared to devices with the maximum number of suspensions.
Innovation Solution
Attaching a plate with a partially constricted section perpendicular to the arm's longitudinal direction to the actuator arms, where the constricted part is located between the plate's leading end and its attachment point, to mimic the natural frequency of suspensions and improve flexibility, thereby maintaining positioning accuracy and frequency characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional plates with high rigidity are attached to actuator arms in place of suspensions, then the mass balance of the actuator is improved, but the natural frequency in the disk radial direction becomes significantly higher and positioning accuracy deteriorates
Solution Approach 1:
The plate is designed with a constricted part (reduced thickness section) at a specific location between the leading end and the arm attachment part. This creates a local region with different rigidity characteristics, allowing the plate to exhibit flexibility similar to suspensions in the critical radial direction while maintaining overall mass balance functionality.
Solution Approach 2:
The thickness of the plate is varied by introducing a constricted part with reduced thickness. This parameter change modifies the plate's rigidity and natural frequency characteristics, enabling it to match the frequency characteristics of suspensions while still providing the required mass balance.
2Productivity
If the number of suspensions on the actuator is reduced to lower manufacturing cost, then production efficiency is improved, but positioning accuracy and frequency characteristics become inconsistent
Solution Approach 1:
The plate is designed to serve multiple functions: it provides mass balance for the actuator arm and simultaneously replicates the flexibility and frequency characteristics of suspensions. This allows actuators with different numbers of suspensions to achieve consistent positioning accuracy without requiring different actuator structures.
Solution Approach 2:
By introducing a constricted part with reduced thickness at a specific location on the plate, the design creates a local flexible region that mimics the mechanical behavior of suspensions. This enables the plate to provide both mass balance and frequency characteristic matching, allowing cost-effective actuators with fewer suspensions to achieve the same positioning accuracy as full-capacity actuators.
3Strength
If plate rigidity is increased to improve mass balance, then actuator stability is improved, but frequency characteristics vary and positioning accuracy cannot be maintained
Solution Approach 1:
The plate employs a constricted part design where only a specific local region has reduced thickness, while other regions maintain sufficient rigidity for mass balance. This localized modification allows the plate to exhibit appropriate flexibility in the radial direction (matching suspension characteristics) while maintaining overall structural integrity and mass balance functionality.
Solution Approach 2:
The thickness parameter of the plate is strategically modified by introducing a constricted part. This parameter change reduces the plate's rigidity in the critical radial direction to match suspension frequency characteristics, while the overall plate structure maintains sufficient strength for mass balance, enabling consistent positioning accuracy across actuators with different suspension counts.
Data Source
AI summary
Embodiments of the present invention relate disk drives, and in particular to realizing a positioning accuracy equal to that of an actuator having the mountable maximum number of suspensions, in an actuator having the smaller number of suspensions than the mountable maximum number. An embodiment of a magnetic disk device includes an actuator having an arm to which a suspension for applying a predetermined load onto a slider with a magnetic head is attached, and an arm to which a plate is attached instead of having the suspension. The plate attached to the arm in place of the suspension has a partially small section with respect to a section perpendicular to an arm longitudinal direction (constricted part), and the constricted part is located between a plate leading end and an arm attachment part.