HDD Base Member Curved Surface Design for Machining Accuracy
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Solution Overview
Problem
The existing methods for manufacturing base members in hard disk drive devices result in reduced assembly accuracy and increased surface roughness due to chatter vibration and undesirable cutting traces during machining, affecting the height accuracy of component placement surfaces.
Innovation Solution
A base member design featuring a cylindrical projection with a curved surface part having a first and second curved surface, where the second curved surface is closer to the component placement part, allowing for improved height accuracy through a two-step machining process using a forming tool and an end mill to minimize chatter and enhance cutting surface quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a forming tool with an R-chamfered part is used to finish the projecting part, then the outer peripheral surface can be machined, but the R shape formed reduces assembly accuracy of components
Solution Approach 1:
The curved surface part is segmented into two distinct curved surfaces (first and second curved surfaces) with different functions. The first curved surface transitions from the cylindrical projection to reduce stress concentration, while the second curved surface provides a smooth transition to the placement surface without forming an R shape that would reduce assembly accuracy. This segmentation allows each surface to optimize its specific function.
Solution Approach 2:
Different regions of the base member are given different surface geometries tailored to their specific functional requirements. The curved surface part has a specific configuration where the first and second curved surfaces are positioned and shaped differently to address local needs: stress distribution at the projection interface and precision at the component placement interface.
2Ease of manufacture
If the forming tool is pressed against the placement surface for machining, then the placement surface can be finished, but chatter vibration occurs due to resistance from the cutting surface
Solution Approach 1:
The curved surface part with its specific geometry of two curved surfaces is designed in advance to optimize the machining process. The gradual transition provided by the first and second curved surfaces allows the cutting tool to engage the material more smoothly, reducing sudden resistance changes that cause chatter vibration during the finishing operation.
3Ease of manufacture
If the forming tool is moved up and down for each projecting part, then each projecting part can be machined individually, but the height positioning accuracy of the forming tool affects the height accuracy of the placement surface
Solution Approach 1:
The curved surface part design creates a geometric relationship where the placement surface height is less sensitive to forming tool positioning variations. The two-curved-surface configuration provides a more robust geometric reference that reduces the impact of height positioning accuracy issues on the final placement surface height.
Data Source
AI summary
A base member includes a projection having a cylindrical shape and projecting in an axial direction and a component placement part. The projection and the component placement part are adjacent to each other via a curved surface part having a first curved surface and a second curved surface. The first curved surface and the second curved surface have a diameter increasing toward the component placement part in the axial direction. The second curved surface is located closer to a side of the component placement part than the first curved surface in the axial direction.