Multi-Thread Self-Tapping Screw for Deteriorated Hole Repair
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Solution Overview
Problem
Conventional fasteners face challenges when dealing with deteriorated receiving cavities, as they may no longer securely thread in due to enlarged diameters, and alignment issues arise when fastening structures with pre-existing holes, often requiring larger screws that are not readily available or involving complex repair processes.
Innovation Solution
A self-tapping screw with multiple thread sizes and cutting surfaces, featuring a proximal threaded portion, a distal threaded portion with a smaller diameter, and an intermediate portion, allowing it to form a cavity in a structure lacking one and aligning pre-existing cavities, thereby accommodating larger diameters and securely fastening structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional fastener is used in a deteriorated receiving cavity, then the fastener can be installed, but it cannot securely thread into the enlarged cavity and the attachment reliability deteriorates
Solution Approach 1:
The fastener body is segmented into multiple threaded portions with different thread sizes (first threaded portion with larger threads, second threaded portion with smaller threads) and a smooth intermediate portion. This segmentation allows different sections to perform different functions: the larger threaded portion engages with deteriorated cavity walls to provide secure anchoring, while the smaller threaded portion engages with intact material for precise positioning and attachment.
Solution Approach 2:
Different portions of the fastener have different local qualities - the first threaded portion has larger thread dimensions suitable for engaging deteriorated cavity surfaces, the intermediate portion has a smooth surface for aligning with pre-existing holes, and the second threaded portion has smaller threads for precise engagement. This local differentiation allows the single fastener to adapt to varying conditions along its insertion path.
2Reliability
If a larger screw is used to accommodate deteriorated receiving cavity, then the attachment reliability improves, but the availability of the fastener deteriorates as larger sizes are not readily available
Solution Approach 1:
The fastener is designed with multi-functionality to serve multiple purposes: it can engage with deteriorated cavities using the larger first threaded portion, align with pre-existing holes using the smooth intermediate portion, and secure attachment using the smaller second threaded portion. This universal design allows a single fastener size to replace what would otherwise require multiple different fastener sizes, improving availability while maintaining reliability.
3Manufacturing precision
If structures with pre-existing holes are fastened, then the alignment of cavities is required, but the alignment precision deteriorates due to difficulty in precisely aligning the cavities
Solution Approach 1:
The smooth intermediate portion of the fastener performs a preliminary action by being inserted through pre-existing holes in both structures before the threaded portions engage with the receiving cavity. This preliminary insertion establishes alignment between the holes and the cavity, ensuring that subsequent threading occurs at the correct position and orientation, thereby improving alignment precision.
4Adaptability or versatility
If a same fastener solves multiple problems (accommodating deteriorated cavities, aligning holes, forming cavities), then the device complexity increases, but the overall system simplicity improves by using one fastener type
Solution Approach 1:
The fastener is segmented into distinct functional portions (first threaded portion, smooth intermediate portion, second threaded portion) that can be manufactured as a single integrated component. This segmentation enables the fastener to perform multiple functions (engaging deteriorated surfaces, aligning holes, securing attachment) while maintaining manufacturability and avoiding the need for multiple separate fastener components.
Data Source
AI summary
A self-tapping fastener or screw is provided including a head, a cutting tip, and a body portion. The cutting tip includes a first cutting surface. The body portion extends from the head along a central axis to the cutting tip. The body portion includes a proximal threaded portion having a proximal thread size; a distal threaded portion having a distal thread size, the distal thread size being smaller than the proximal thread size; and an intermediate portion, the intermediate portion of the body portion disposed between the proximal threaded portion and the distal threaded portion.