Blind-Hole Fastener Shank Geometry for Higher Holding Force
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Solution Overview
Problem
Existing fastening methods and systems fail to ensure a large holding force of the fastening element on a substrate for a given blind hole depth, as the shank's external dimensions often do not effectively displace and weld with the substrate material.
Innovation Solution
A fastening method and system where the shank of the fastening element has an end face with a peripheral surface that is inclined or stepped relative to the fastening direction, allowing it to displace substrate material and weld securely within a blind hole, with a cross-sectional area increasing along the direction of attachment and an angle of inclination between 1° and 6°, enhancing the holding force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the shank has a blunt end face with outer dimensions exceeding the blind hole diameter to displace substrate material, then the holding force is improved, but the insertion difficulty and energy expenditure increase
Solution Approach 1:
The end face of the shank is segmented into multiple inclined surfaces (first inclined surface, second inclined surface, etc.) with different angles relative to the fastening direction. This segmentation allows different portions of the shank to interact with the substrate material at optimal angles, improving holding force while facilitating gradual insertion through the blind hole.
Solution Approach 2:
Different regions of the end face are given different local qualities through varying inclination angles. The first inclined surface has a different angle than the second inclined surface, creating localized optimal conditions for both material displacement and insertion ease in different angular zones.
2Strength
If the circumferential surface is inclined at a larger angle to improve welding and holding force, then the strength increases, but the energy expenditure and insertion difficulty increase
Solution Approach 1:
The inclination angle of the circumferential surface is optimized within a specific range (1° to 6°) relative to the fastening direction. This parameter optimization ensures sufficient welding strength and holding force while minimizing the energy required for insertion and material displacement.
Solution Approach 2:
The end face combines multiple inclined surfaces with different angles, creating a composite geometric structure that achieves optimal balance between welding strength and energy efficiency. The combination of angles allows different material interaction modes to work together.
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 solution significantly increases the holding force of the fastening element on the substrate by ensuring a secure weld at the peripheral surface, with optimal energy expenditure and ease of insertion, maintaining a constant blind hole diameter and using a bolt-firing tool for precise alignment.
Implementation Method 1
when the shank is driven into the blind hole, it displaces a portion of the substrate material in the depth direction
Implementation Method 2
welds to the substrate at the circumferential surface
Data Source
Figure 1
Figure 2~3
AI summary
Fastening element for fastening to a substrate consisting of a substrate material, wherein a blind hole is created in the substrate and a fastening element is anchored in the blind hole, wherein a shaft of the fastening element defines a fastening direction and has a circumferential surface which is inclined or stepped relative to the fastening direction.