Wedge Fastener Sleeve Reduces Assembly Time and Particle Generation
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Solution Overview
Problem
Conventional fasteners, such as screws, require multiple revolutions to engage threads effectively, leading to prolonged assembly times in high-volume manufacturing and can generate metal particles that interfere with disk drive operations.
Innovation Solution
A fastener design featuring a shaft with a sleeve that moves between two rotational positions, utilizing a wedge-like configuration and ribs to minimize relative motion and secure engagement, reducing assembly time and particle generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional screws with mating threads are used to connect cover and base, then secure coupling is achieved, but assembly time increases significantly due to multiple revolutions required for thread engagement
Solution Approach 1:
The fastener is divided into two separate components: a shaft and a sleeve. The shaft contains drive features and engagement features, while the sleeve contains corresponding mating features. This segmentation allows the components to be inserted and secured in a single linear motion without requiring multiple rotational revolutions for thread engagement, thus reducing assembly time while maintaining coupling security.
Solution Approach 2:
The shaft and sleeve are designed with pre-configured engagement features (such as tapered surfaces, ribs, or cam mechanisms) that automatically engage when the components are inserted into the housing. This preliminary configuration eliminates the need for multiple revolutions during assembly, as the engagement features lock the components in place immediately upon insertion, thereby reducing assembly time while ensuring secure coupling.
2Reliability
If conventional metal screw threads are used for coupling, then secure connection is achieved, but metal particles are generated that can interfere with disk drive operation
Solution Approach 1:
The fastener components (shaft and sleeve) are designed to be made from non-metallic materials such as plastics, polymers, or composite materials instead of traditional metals. These materials provide sufficient mechanical strength and friction-based engagement to secure the cover and base together, while eliminating the generation of metal particles that could contaminate the disk drive interior and interfere with its operation.
3Reliability
If a sleeve with varying thickness is used in the fastener design, then secure engagement through wedge action is achieved, but manufacturing complexity increases
Solution Approach 1:
The sleeve is designed with varying thickness at different locations: thicker at the distal end and thinner at the proximal end. This local variation in quality creates a wedge action that enhances engagement security when the fastener is inserted, while still being manufacturable using standard processes such as injection molding or extrusion. The varying thickness is integrated into the sleeve's geometry without requiring complex assembly steps, thus maintaining ease of manufacture while achieving secure engagement.
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 fastener design significantly reduces assembly time and minimizes particle interference, providing secure and efficient coupling of components in disk drives and other applications.
Implementation Method 1
The sleeve comprises an inner surface adjacent the shaft... The first thickness is less than the second thickness... A cross-sectional centroid of the shaft between the upper extent and the lower extent is in substantially the same location in both the first and second rotational positions
Implementation Method 2
wedge-like configuration and ribs to minimize relative motion and secure engagement
Data Source
AI summary
A fastener comprises a shaft extending along a longitudinal axis, and a sleeve wrapped partially around the shaft. The sleeve comprises an inner surface adjacent the shaft, an outer surface, an upper extent, a lower extent, a first circumferential extent, a second circumferential extent, and a gap extending longitudinally from the upper extent to the lower extent and separating the first circumferential extent from the second circumferential extent. The sleeve has a first thickness adjacent the first circumferential extent that is less than a second thickness between the second circumferential extent and the first circumferential extent. A cross-sectional centroid of the shaft between the upper extent and the lower extent is in substantially the same location, with the sleeve in different first and second rotational positions.