Laser Welding Disk Enclosure Cover Bead Overlap
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Solution Overview
Problem
Conventional magnetic disk devices face challenges in reducing the time required for laser welding while maintaining improved airtightness and seal performance, as the pitch of laser beam irradiation is typically less than the diameter of weld beads, leading to prolonged welding times and compromised seal quality.
Innovation Solution
The method involves setting the pitch of laser beam irradiation greater than the diameter of weld beads, allowing for continuous welding without waiting for each bead to solidify, and using multiple overlapping circuits to ensure airtight sealing, such as in the first embodiment where three circuits of circular beads are used, and in the second embodiment, employing a galvano scanner for efficient laser beam scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pitch of laser beam irradiation is set less than the diameter of weld beads to ensure seal performance, then airtightness is improved, but laser welding time is prolonged
Solution Approach 1:
The patent applies periodic action by using pulse irradiation of the laser beam, where the laser is turned on and off repeatedly during welding. This allows the weld beads to solidify between pulses while maintaining progress along the sealing line, resolving the contradiction between ensuring adequate seal performance and reducing total welding time
Solution Approach 2:
The patent implements continuity of useful action by setting the pitch of laser beam irradiation greater than the diameter of weld beads, allowing continuous welding progression without waiting for complete solidification of each bead. Multiple overlapping circuits ensure airtight sealing while maintaining continuous motion, significantly reducing welding time from one to two minutes to about thirty seconds
2Productivity
If the pitch of laser beam irradiation is set greater than the diameter of weld beads to reduce welding time, then productivity is improved, but seal performance may be compromised
Solution Approach 1:
The patent resolves the contradiction by adding another dimension to the welding process - using multiple overlapping circuits instead of relying solely on pitch reduction. The weld beads are arranged in multiple circuits that overlap with each other, creating redundant sealing paths that ensure airtightness even with larger pitch spacing, thus maintaining seal performance while enabling faster welding speed
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 approach significantly reduces the time for laser welding, achieving airtight seals and improving manufacturing efficiency, with the first embodiment completing the welding of a 3.5-inch HDD in about thirty seconds compared to one to two minutes in conventional methods, while maintaining enhanced seal performance.
Implementation Method 1
a peripheral edge portion of a cover (16) including a welded portion laser-welded to a base (12)
Implementation Method 2
pulse irradiation is used as a laser irradiation method and the top cover is irradiated with a laser beam while laser output is repeatedly turned on and off
Data Source
AI summary
According to one embodiment, a disk device includes a rotatable disk-shaped recording medium, an actuator supporting a head to be movable with respect to the recording medium, and an enclosure includes a base accommodating the recording medium and the actuator, and a cover fixed to the base and includes a peripheral edge portion including a welded portion laser-welded to the base. The welded portion includes weld beads arranged along the entire peripheral edge portion of the cover, and the weld beads include at least two circular weld beads in the peripheral edge portion of the cover.