Self-clinching fastener with radial projections and spline teeth
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Solution Overview
Problem
Existing self-clinching fasteners have limited torque-out and push-out resistance, require tight tolerances for hole size and sheet thickness, and are costly to attach to thick materials due to the need for additional machining and special die tooling, especially when dealing with rough punched holes.
Innovation Solution
A self-clinching fastener design featuring a head with radial projections and spline teeth that provide anti-rotation and increased torque-out resistance, allowing secure attachment to ductile materials of varying thickness without special geometry or pre-formed surfaces, using a die to displace and clinch material into recesses for secure embedding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If typical self-clinching fasteners are pressed into pre-punched holes in ductile metal, then the fastener is permanently attached to the metal, but torque-out resistance and push-out resistance are limited
Solution Approach 1:
The fastener head is segmented into multiple functional zones: an embedded portion with knurls for torque-out resistance, a clinching portion with radial projections for material displacement, and a sealed portion for push-out resistance. This segmentation allows each zone to independently contribute to different aspects of attachment strength and reliability.
Solution Approach 2:
The fastener utilizes composite structural features combining different material deformation mechanisms: cold flow of ductile metal into knurl recesses, plastic deformation around radial projections, and elastic recovery of the sealed portion. This composite approach to material interaction enhances both torque-out and push-out resistance simultaneously.
2Stability of the object's composition
If existing self-clinching fasteners include features that prevent rotation such as serrated rings or knurled studs, then the fastener is secured to the metal sheet, but tight tolerances are required for hole size and sheet thickness
Solution Approach 1:
The fastener design changes the geometric parameters of the embedded portion, using knurls with specific pitch and depth ratios that allow accommodation of larger tolerance ranges in hole size and sheet thickness. The knurl geometry is optimized to maintain adequate engagement depth across a broader parameter range compared to conventional serrated rings.
Solution Approach 2:
The radial projections automatically adjust their engagement depth based on the actual sheet thickness and hole size within a reasonable tolerance range, eliminating the need for precise pre-setting of anti-rotation features. The self-adjusting mechanism absorbs dimensional variations without requiring tight manufacturing tolerances.
3Ease of operation
If self-clinching fasteners are pressed into holes that are slightly too large, then installation is easier, but there may be insufficient material to flow into the recesses and features of the fastener causing weaker connection
Solution Approach 1:
The fastener transitions from relying solely on radial material flow (2D plane) to incorporating axial material displacement through radial projections (3D volume). This dimensional change allows the fastener to engage material from both radial and axial directions, maintaining connection strength even when hole size is larger than nominal.
Solution Approach 2:
The knurls on the embedded portion perform preliminary material deformation and compaction before the main clinching action occurs. This preliminary action pre-conditiones the material, increasing its density and deformability, which ensures adequate material flow into the clinching recesses even when starting with a larger hole.
4Adaptability or versatility
If sheet thickness increases, then the fastener can accommodate thicker materials, but additional machining such as drilling and counter-boring is required combined with special die tooling
Solution Approach 1:
The fastener design integrates multiple functions into a single component: the embedded portion provides anti-rotation for thin sheets, the clinching portion handles material displacement for medium thickness, and the sealed portion provides push-out resistance for thick materials. This multi-functional design eliminates the need for different fastener types or additional machining operations across various thickness ranges.
Solution Approach 2:
The radial projections act as an intermediary mechanism that bridges the gap between the fastener body and the sheet material for thick sheets. These projections displace and compact material axially, providing adequate engagement without requiring counter-boring or special die tooling that would otherwise be necessary for thick material attachment.
5Force
If knurled shoulder sections are used to resist torque-out, then torque-out resistance is provided, but shallow tooth depth makes them ill-suited for rough punched holes requiring subsequent hole reaming
Solution Approach 1:
The knurls on the embedded portion perform preliminary material deformation and compaction during the fastener installation process itself, before any subsequent machining operations. This preliminary action creates a reinforced zone around the hole that actually improves the quality of rough punched holes rather than requiring reaming to correct deficiencies.
Solution Approach 2:
Instead of using shallow knurls that require pre-formed holes, the invention uses deeper knurl geometry that actively improves the hole quality during installation. The inversion is in the causal relationship: rather than hole quality being a prerequisite, the fastener installation becomes the process that creates the necessary hole quality.
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 and push-out resistance, simplifies attachment to various thicknesses without additional machining, and maintains a complete seal for gasket attachment, improving reliability and cost-effectiveness.
Implementation Method 1
the ductile metal cold flows into recesses and features of the self-clinching fastener to secure it to the metal
Data Source
AI summary
A self-clinching fastener for insertion into ductile sheets of varying thicknesses has increased push-out and torque-out resistance. The self-clinching fastener includes a plurality of radial projections and spline teeth that embed into the ductile sheets, causing the material to cold flow into a recess, thereby permanently clinching the self-clinching fastener to the ductile sheet.