Self-Clinching Fastener Lugs for Thread-Safe Panel Attachment

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Solution Overview

Problem

Conventional self-clinching fasteners fail to reliably attach to lightweight metal panels with enhanced strength properties, experiencing low pull-out resistance and distortion of internal threads due to limited elongation of new materials during plastic deformation.

Innovation Solution

A self-clinching fastener design featuring a body portion with an annular-shaped surface, a punch portion with cylindrical profile and cutouts, and radially aligned lugs with a contact face that declines outwardly, reducing the need for material elongation and preventing voids during attachment, while eliminating sharp edges to prevent cracking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional self-clinching fasteners are used with lightweight metal panels having enhanced strength properties, then the fasteners can be attached to the panels, but the fasteners experience low pull-out resistance and distortion of internal threads due to limited elongation of the new materials during plastic deformation

Engineering Contradiction:

Improvepull-out resistanceVSAvoidthread distortion

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The punch portion is segmented with multiple cutouts arranged circumferentially, creating discrete deformation zones that distribute the plastic deformation requirements across multiple locations rather than requiring continuous material flow, thereby reducing thread distortion while maintaining pull-out resistance

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The fastener design incorporates localized deformation features including the punch cutouts and lug contact faces that concentrate plastic deformation in specific areas away from the thread region, allowing the bulk material to maintain its strength properties while localized zones accommodate the necessary deformation

Inventive Principle:

Principle #3Local quality

2Strength

If conventional forming techniques are used to deform metal panel into double-undercut groove, then pull-out resistance is improved, but the deformation is difficult to obtain resulting in inconsistent pull-out resistance

Engineering Contradiction:

Improvepull-out resistanceVSAvoiddeformation consistency

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The punch portion with pre-formed cutouts creates deformation zones before the final clinching operation, preparing the metal panel for controlled deformation into the annular groove, which ensures consistent deformation results and reliable pull-out resistance

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The annular groove is formed with a curved, rounded profile rather than sharp angular undercuts, allowing the metal panel to deform more uniformly and consistently into the groove, thereby achieving reliable pull-out resistance across varying material conditions

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Strength

If lugs with flat faces are provided to enhance torque-out resistance, then torque-out resistance and push-out resistance are improved, but the design requires significant material elongation that new lightweight materials cannot provide

Engineering Contradiction:

Improvetorque-out resistanceVSAvoidmaterial compatibility

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The lug contact faces are designed with inclined surfaces at specific angles rather than flat faces, changing the deformation parameter from requiring extensive material flow to utilizing controlled plastic deformation at an angle, which is achievable with high-strength lightweight materials while maintaining torque-out resistance

Inventive Principle:

Principle #35Parameter changes

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 design enhances torque-out resistance and meets industrial standards for attachment to lightweight metal panels with improved joint strength and reduced production costs, ensuring consistent performance and reliability.

Implementation Method 1

The contact face is configured to engage the metal substrate. The design enhances torque-out resistance and meets industrial standards for attachment to lightweight metal panels with improved joint strength

Methodology Applied

Scientific EffectPlastic deformation: Plasticity

Implementation Method 2

Methodology Applied

Scientific EffectMechanical constraint:

Implementation Method 3

The clinch nut is attached to the metal panel by a die member which forms a mechanical interlock between the clinch nut and the metal panel

Methodology Applied

Scientific EffectMechanical interlocking:

Data Source

PatentUS11209040B2Self-clinching fastener

Publication Date: 2021.12.28 RB&W MANUFACTURING LLC

AI summary

A self-clinching fastener for attachment to a plastically deformable metal panel includes a body portion with a central axis, the body portion has an outer peripheral surface extending in a direction perpendicular to the central axis. A punch portion is coaxial with the central axis and extends from the body portion such that the annular-shaped surface encircles the punch portion, the punch portion includes an outer peripheral surface extending in the direction of the central axis. A plurality of spaced apart lugs encircle the punch portion and axially projecting outwards from the annular-shaped surface, one of the lugs has a contact face configured to engage the metal substrate, the contact face declining, relative to an imaginary horizontal plane on which the annular-shaped surface lies, in a radially outwards direction of the self-clinching fastener.