Disk Drive Base Unit Exposed Inner Wall for Laser Welding
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Solution Overview
Problem
In disk drive devices, the electrodeposition coating on inner peripheral surfaces can burn and generate combustion products during welding, leading to improper welding and decreased cleanliness within the casing due to heat conduction from laser welding processes.
Innovation Solution
The base unit design includes exposed surfaces on the inner wall surfaces of the housing, specifically the upper end face and adjacent regions, which are not covered by the electrodeposition coating, preventing combustion product generation and scattering during welding by allowing high-temperature heat to be dissipated without affecting the coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the entire surface of the base unit is coated with electrodeposition coating to prevent dust generation, then dust prevention is improved, but combustion products are generated during laser welding due to heat conduction to the coating
Solution Approach 1:
The patent applies electrodeposition coating only to specific surfaces (outer peripheral surface of the sidewall and bottom surface of the base) that are远离 from the laser welding zone. The inner peripheral surface of the upper sidewall is intentionally left uncoated, creating local quality differentiation where coating is present only where dust prevention is needed without causing welding contamination.
Solution Approach 2:
The coating application is segmented into different zones: coated zones on the outer peripheral surface and bottom surface for dust prevention, and an uncoated zone on the inner peripheral surface of the upper sidewall to prevent combustion during welding. This spatial segmentation resolves the contradiction between comprehensive coating and welding cleanliness.
2Object-affected harmful factors
If electrodeposition coating is applied near the joint portion for dust prevention, then dust generation is reduced, but improper welding occurs due to combustion of the coating during joining
Solution Approach 1:
The patent creates local quality differentiation by applying electrodeposition coating only to the outer peripheral surface of the sidewall and bottom surface, while leaving the inner peripheral surface of the upper sidewall uncoated. This ensures that the coating is present where dust prevention is critical (outer surfaces) but absent where it would interfere with welding (inner surface near joint).
Solution Approach 2:
The patent extracts the electrodeposition coating from the welding zone (inner peripheral surface of upper sidewall) while retaining it on non-welding surfaces. This selective removal of coating from the critical welding area prevents combustion during laser welding while maintaining dust prevention benefits on other surfaces.
3Strength
If the first cover is joined to the sidewall using laser welding with full peripheral irradiation, then joining strength is improved, but heat conduction to the inner peripheral surface causes coating combustion and cleanliness degradation
Solution Approach 1:
The patent applies local quality differentiation to the sidewall surface: the outer peripheral surface receives electrodeposition coating for dust prevention, while the inner peripheral surface of the upper sidewall is left uncoated. This allows full peripheral laser welding for strong joining without combustion of coating in the welding zone, maintaining housing cleanliness.
Solution Approach 2:
The patent converts the potential harm of heat conduction during welding into a beneficial arrangement by strategically placing the uncoated zone on the inner peripheral surface. The heat from laser welding naturally protects this area by preventing coating combustion, while the coated outer surfaces still provide dust prevention. The heat that would be harmful becomes acceptable because the coating is already absent in that specific zone.
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 effectively prevents combustion product generation from the electrodeposition coating, maintaining the cleanliness of the housing and ensuring proper welding, thereby enhancing the overall integrity and cleanliness of the disk drive device.
Implementation Method 1
an entire surface of the base being subjected to electrodeposition coating in order to prevent generation of dust
Implementation Method 2
the first cover is irradiated with a laser beam while a center of a laser spot is controlled, whereby the first cover is joined to an upper surface of the sidewall of the base by laser welding
Data Source
AI summary
A base unit includes a support to support a motor, a bottom plate, and a wall. The bottom plate extends radially outward from the support. The wall extends upward from an outer periphery of the bottom plate, and includes a rectangular opening in planar view. Surfaces of the bottom plate and the wall include a cover surface covered with an electrodeposition coating film and an exposed surface in which a material of the base unit is exposed from the electrodeposition coating film. At least an upper end surface of the wall and a partial region of an inside wall surface of the wall continuous with the upper end surface are each the exposed surface.