Disk Drive Base Plate Casting Design for Helium Leakage Prevention
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Solution Overview
Problem
Conventional disk drive apparatus base plates experience poor fluidity of molten metal during casting, leading to potential helium gas leakage due to shrinkage cavities in the actuator attachment part.
Innovation Solution
A base plate design with a casting process that includes a rectangular bottom plate, a pivot post, and a bridge, where the bridge is cut and an electrodeposition coating film is applied, enhancing the fluidity of molten metal and reducing shrinkage cavities, and an impregnation process seals any machined surfaces to prevent gas leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the actuator attachment part is designed to protrude upward from the bottom surface part, then the actuator can be attached to the base plate, but the fluidity of molten metal to the actuator attachment part becomes poor during casting, causing shrinkage cavities
Solution Approach 1:
A protrusion is provided on the pivot post before casting to guide molten metal flow toward the actuator attachment part. This preliminary structural feature ensures proper fluidity distribution during the casting process, preventing shrinkage cavities while maintaining the attachment function.
Solution Approach 2:
The base plate is designed with non-uniform thickness, featuring a thinner actuator attachment part and a thicker bottom surface part. This local quality variation optimizes metal flow distribution during casting, ensuring adequate filling of the protruding actuator attachment area while maintaining structural integrity.
2Manufacturing precision
If the base plate is designed with a thin actuator attachment part, then metal fluidity improves during casting, but the structural strength of the attachment part decreases
Solution Approach 1:
The base plate employs varying thickness throughout its structure - the actuator attachment part is thinner to ensure proper metal fluidity during casting, while the bottom surface part is thicker to provide overall structural support and strength. This localized quality variation resolves the contradiction between castability and strength.
Solution Approach 2:
The protrusion structure on the pivot post is designed in advance to guide molten metal flow, ensuring that the thin actuator attachment part receives adequate metal supply during casting. This preliminary design feature prevents shrinkage cavities even in the thinner section, maintaining both fluidity and structural integrity.
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 reduces shrinkage cavities and enhances the structural integrity of the base plate, preventing helium gas leakage and improving the manufacturing process efficiency.
Implementation Method 1
an electrodeposition coating film covering at least a portion of a surface of the base body
Data Source
AI summary
A base plate is a portion of a housing of a disk drive apparatus, including a base body being a casting product, and an electrodeposition coating film covering at least a portion of a surface of the base body. The base body includes a bottom plate rectangular as viewed from an axial direction, a pivot post, and a protrusion. The bottom plate extends perpendicular to a rotation axis of a disk that extends vertically and a swing axis of a head that is disposed in a different position from the rotation axis and that extends vertically. The head reads or writes information from or to the disk. The pivot post protrudes upward from an upper surface of the bottom plate along the swing axis. The protrusion is provided protruding radially outward from a peripheral surface of the pivot post and protruding to the upper surface of the bottom plate.