Fastener With Stepped Pin And Inclined Leg For Wide Thickness Range
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Solution Overview
Problem
Existing fasteners for attaching upholstery trim boards to vehicle body panels face a challenge in maintaining strong fastening force when the hinge portion is elongated in the axial direction, leading to potential bending and reduced attachment security across varying thickness ranges.
Innovation Solution
A fastener design featuring a grommet with expandable leg pieces and a pin member that includes a stepped tapered surface, allowing for secure engagement with attachment holes across wide thickness ranges while maintaining strong fastening force, utilizing a recessed inclined surface to enhance the push-back force and prevent premature disengagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the hinge portion is made long in the axial direction to fasten thick upholstery components and panel members, then the fastener can accommodate wider thickness ranges, but the hinge portion becomes prone to bending which weakens the fastening force
Solution Approach 1:
The leg piece is designed with non-uniform thickness: a thinner bendable portion for expansion and a thicker portion for strength. This local quality variation allows the leg piece to be elongated for thickness adaptability while the thicker portion maintains fastening force by resisting bending.
Solution Approach 2:
The leg piece is segmented into functionally distinct portions: a bendable portion with smaller thickness for expansion movement and a thicker portion for providing structural strength. This segmentation allows each portion to optimize its function without compromising the other.
2Adaptability or versatility
If the bendable portion is elongated to accommodate thicker attachment members, then the fastener can attach to wider thickness ranges, but the fastening force is reduced due to increased bending susceptibility
Solution Approach 1:
The leg piece incorporates a thicker portion that provides structural support and resistance to bending, while the thinner bendable portion allows for expansion. This local quality differentiation ensures that even when the bendable portion is elongated for thickness adaptability, the thicker portion maintains attachment security by preventing excessive bending.
3Adaptability or versatility
If the leg pieces are made with larger expansion capability to secure wide thickness ranges, then the fastener can accommodate more varied attachment members, but the fastening force is weakened due to increased flexibility
Solution Approach 1:
The leg piece is designed with a thinner bendable portion that enables large expansion for thickness adaptability, combined with a thicker portion that provides the structural strength needed for fastening. This local quality variation resolves the contradiction between expansion capability and fastening force.
Solution Approach 2:
The leg piece is divided into a bendable portion for expansion and a thicker portion for strength. This segmentation allows the bendable portion to provide adaptability while the thicker portion maintains the necessary fastening force.
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 effectively secures a wide range of attachment members with enhanced fastening force and reduced risk of attachment failure, even when the bendable portions are elongated, ensuring stability and reliability in vehicle assembly.
Implementation Method 1
an inclined surface which is formed so as to be distant from an inner surface of the bendable portion inward in a radial direction, which is inclined downward as it approaches toward a center axis, and which receives a push-in force from the pin member when the pin member is pushed in
Implementation Method 2
a bendable portion which projects downward from the head portion and which is bendable to be expanded
Data Source
AI summary
A fastener attached to an attachment hole of an attachment member, wherein a grommet has a head section having an opening, and a plurality of leg pieces having an outer surface capable of engaging with an edge of the attachment hole of the attachment member by expansion of the leg pieces. A pin member is pressed in from the opening to splay the plurality of leg pieces. The leg pieces each have: a flexure section that extends downward from the head section and is flexible for spreading out; and an inclined surface that is formed radially inwardly away from an inner surface of the flexure section, inclined downwardly toward the center axis, and subjected to a pressing force from the pin member when the pin member is pressed in.