Disk Drive Base Rib Structure for Airtight Circumferential Welding
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Solution Overview
Problem
In magnetic disk drives, achieving high airtightness while maintaining stable welding quality is challenging due to the need for thinner sidewalls, which reduces the area for welding and can degrade the welding quality, especially when increasing the diameter of the magnetic disk.
Innovation Solution
The design incorporates a fixing rib with alternating regions of different widths and a chamfered surface around the circumference, allowing for a consistent welding surface width and maintaining high welding quality, even with thinner sidewalls, by using recessed portions and a gasket to ensure airtightness and expandable mounting surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the outer diameter of the magnetic disk is increased, then the storage capacity is improved, but the wall portion of the base needs to be formed thinner which decreases the area of the welded portion and degrades the welding quality
Solution Approach 1:
The base is divided into a wall portion and a rib portion that protrudes from the wall. The rib is further segmented into a first region with a first width and a second region with a second width less than the first width. This segmentation allows the welding surface to be formed on the rib rather than the thin wall portion, enabling stable welding quality even when the wall thickness is reduced to accommodate larger magnetic disks.
Solution Approach 2:
The welding surface is moved from the two-dimensional wall surface to the three-dimensional rib structure that protrudes from the wall. By creating a rib with different width regions, the welding area is expanded in the radial direction while maintaining sufficient thickness for high-quality welding, thus resolving the contradiction between increased disk diameter and maintained welding quality.
2Length of moving object
If the wall portion of the base is formed thinner, then the area for welding is decreased, but high airtightness is required which necessitates stable welding quality all around the circumference
Solution Approach 1:
The base structure is segmented into wall portion and rib portion, with the rib providing a dedicated welding surface. This segmentation allows the wall to be made thinner for larger disk capacity while the rib maintains sufficient thickness for reliable welding, ensuring airtightness is not compromised by reduced wall thickness.
Solution Approach 2:
Different regions of the base have different structural characteristics: the wall portion is thin to accommodate large disk diameter, while the rib portion has increased thickness specifically at the welding surface to ensure high welding quality. This local quality differentiation allows both thin walls and reliable airtight welding to coexist.
3Area of stationary object
If the area of the welded portion is decreased, then the welding quality is degraded, but stable welding quality all around the circumference is necessary to obtain high airtightness
Solution Approach 1:
The rib is segmented into first and second regions with different widths. The first region has a larger width that provides an extended welding surface area, ensuring sufficient welding area for high-quality circumferential welding. The second region has a reduced width for other functional requirements. This segmentation resolves the contradiction by providing adequate welding area in the first region.
Solution Approach 2:
The welding surface is elevated to a separate rib structure that protrudes from the wall portion. This dimensional change creates additional welding area on the rib's outer surface, allowing sufficient welding area to be achieved without increasing the wall thickness, thereby maintaining both adequate welding area and high airtightness.
Data Source
AI summary
According to one embodiment, a disk device includes a disk-shaped recording medium, a base accommodating the recording medium, the base including a bottom wall, a sidewall on a peripheral portion of the bottom wall, and a rib on a part of an upper surface of the sidewall and extending along an entire circumference of the sidewall, a first cover on a part of the upper surface of the sidewall, and a second cover on a first surface of the rib and above the first cover. The rib includes a first region with a first width, a second region with a second width less than the first width, and the first surface with a fixed width around an entire circumference of the rib. The first region and the second region are located corresponding to a side portion of the recording medium.