Disk Drive Actuator Single Metal Component Thermal Stability
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Solution Overview
Problem
Conventional bonded coil actuator designs in disk drives face thermal dissipation issues due to material mismatch in thermal expansion coefficients, leading to mechanical instability and 'coil popping', while traditional overmolded designs have manufacturability, bond strength, and cost disadvantages.
Innovation Solution
A bonded coil actuator configuration where the actuator body, wrap-around support, and tang are a single metal component, with the coil positioned radially between the tang and axis of rotation, facilitating improved heat dissipation through conduction and avoiding encirclement to prevent eddy currents, and using a bobbin with epoxy adhesive for attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a plastic overmold is used to couple the coil to the actuator body, then ease of manufacture is improved, but thermal dissipation problems occur leading to mechanical instability and coil popping
Solution Approach 1:
The patent introduces a metal support structure as an intermediary component between the coil and the actuator body. This metal support serves as a thermal conductor to dissipate heat from the coil while providing mechanical stability, eliminating the need for plastic overmold that causes thermal dissipation problems. The metal support acts as a mediator that transfers heat away from the coil to the metal components, preventing thermal buildup and associated mechanical instability.
Solution Approach 2:
The patent changes the material parameter of the support structure from plastic to metal. This material parameter change fundamentally alters the thermal conduction properties, transforming the thermal management characteristics of the assembly. By using metal with high thermal conductivity instead of plastic with low thermal conductivity, the system effectively changes its thermal dissipation capability, resolving the thermal dissipation problem while maintaining ease of manufacture through the metal support structure.
2Temperature
If traditional bonded coil designs are used, then thermal dissipation is improved, but manufacturability and bond strength are compromised
Solution Approach 1:
The patent segments the support structure into distinct components: a metal support structure and a separate coil assembly. This segmentation allows each component to be manufactured independently using optimized processes, then assembled together. The metal support can be manufactured using standard metal fabrication techniques, while the coil can be wound and attached separately, improving overall manufacturability while maintaining thermal dissipation benefits through the metal support structure.
3Stability of the object's composition
If the wrap-around support encircles the coil, then structural stability is improved, but eddy currents are generated causing mechanical instability
Solution Approach 1:
The patent extracts the encircling portion from the support structure, creating a wrap-around support that extends radially beyond the coil without completely encircling it. This extraction removes the closed loop that would generate eddy currents when exposed to changing magnetic fields from the coil. The support structure maintains structural stability through alternative geometric configurations while eliminating the harmful eddy current path by removing the complete encirclement of the coil.
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 configuration enhances thermal stability, reduces mechanical instability, and improves manufacturability and cost-effectiveness by maintaining material continuity and efficient heat dissipation, while avoiding the drawbacks of overmolded designs.
Implementation Method 1
An actuator coil is supported by the actuator body opposite the actuator arms. The actuator coil is configured to interact with one or more magnets, typically a pair, to form a voice coil motor.
Implementation Method 2
The actuator coil is configured to interact with one or more magnets, typically a pair, to form a voice coil motor. The printed circuit board assembly selectively controls current passing through the actuator coil that results in a torque being applied to the actuator.
Implementation Method 3
The actuator body, the wrap-around support, and the tang are all a single component comprising a metal material having material continuity rather than an assembly of subcomponents.
Data Source
AI summary
There is provided an actuator for a disk drive. The actuator includes an actuator body defining an axis of rotation. The actuator further includes a coil. The actuator further includes a wrap-around support extending from the actuator body radially beyond the coil with respect to the axis of rotation without encircling the coil. The actuator further includes a tang supported by the wrap-around support. The coil is positioned radially between the tang and the axis of rotation. The actuator body, the wrap-around support, and the tang are all a single components comprising a metal material having material continuity rather than an assembly of subcomponents.