Disk Drive Base Plate Recess Layout for Shrinkage-Free Pivot Posts
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Solution Overview
Problem
Conventional base plates for disk drives, formed by casting, often suffer from shrinkage cavities in the pivot post due to insufficient filling of molten metal, which reduces the quality and reliability of the disk drive components.
Innovation Solution
A cast base plate design featuring a base body with a bottom plate and pivot post, where the bottom plate includes a thin bottom with recesses to guide the molten metal flow effectively, ensuring the pivot post is adequately filled during the casting process, and an electrodeposition coating film is applied to enhance surface coverage and quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the cavity corresponding to the pivot post is formed as an elongated columnar shape in the casting process, then the base plate can be manufactured by conventional casting methods, but the molten metal cannot be sufficiently filled in the cavity, causing shrinkage cavities in the pivot post
Solution Approach 1:
The invention divides the base plate into two parts: a main body portion and a pivot post portion. The pivot post portion is formed separately and then attached to the main body portion. This segmentation allows the pivot post to be manufactured with high precision using forging or machining, while the main body can be produced by conventional casting, thus resolving the contradiction between ease of manufacture and manufacturing precision.
Solution Approach 2:
The invention combines two different manufacturing processes: casting for the main body portion and forging/machining for the pivot post portion. The pivot post portion is produced with high precision through separate manufacturing and then attached to the cast main body, merging the advantages of both casting (ease of manufacture) and forging/machining (high precision) to eliminate shrinkage cavities while maintaining manufacturing efficiency.
2Manufacturing precision
If the base plate is formed by forging, then the pivot post can be manufactured with high precision, but the production cost and complexity increase compared to casting
Solution Approach 1:
The base plate is segmented into a main body portion (manufactured by cost-effective casting) and a pivot post portion (manufactured with high precision through forging or machining). This segmentation allows high precision to be applied only where necessary, reducing overall manufacturing complexity while maintaining dimensional accuracy of the pivot post.
Solution Approach 2:
The invention applies different manufacturing qualities to different parts of the base plate: the main body portion uses conventional casting suitable for general structural requirements, while the pivot post portion uses high-precision forging or machining only where dimensional accuracy is critical. This local quality approach reduces overall device complexity while ensuring pivot post precision.
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 design effectively suppresses the occurrence of shrinkage cavities in the pivot post, improving the reliability and quality of the disk drive by ensuring proper filling of molten metal and enhancing the accuracy of the pivot post's dimensions, thus supporting precise operation of the head and spindle motor.
Implementation Method 1
an electrodeposition coating film that covers at least part of a surface of the base body
Data Source
AI summary
A base plate includes a base body including a bottom plate and a pivot post, and an electrodeposition coating film. The bottom plate extends perpendicular to a first axis, a rotation axis of the disk, and a second axis, a swing axis of a head; and, when viewed from an axial direction, has a rectangular shape with a first direction as a short side direction and a second direction as a long side direction. The pivot post protrudes upward from an upper surface of the bottom plate at a position overlapping the second axis. The bottom plate has a thin bottom arranged in a radially outward direction orthogonal to the second axis of the pivot post and including at least one of a lower recess recessed upward from a lower surface of the bottom plate and an upper recess recessed downward from the upper surface of the bottom plate.