Clinch Fastener Rib Geometry for Low-Warping Workpiece Staking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional clinch fasteners often cause high stress areas and warping in workpieces due to uneven material displacement during installation, leading to undesirable joint characteristics such as cock-eyed fasteners and increased distortion.
Innovation Solution
The clinch fastener features a plurality of ribs under its head, designed with multiple sections and a parametric profile that radially displace workpiece material into a retaining groove, diffusing stress and minimizing warping by providing a more uniform stress distribution through radially focused material displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional clinch fasteners are pressed into the workpiece, then the fastener is securely installed with high retention, but high stress areas cause warping and distortion of the workpiece
Solution Approach 1:
The head of the clinch fastener is segmented into multiple ribs (typically three) that are distributed around the circumference. Each rib independently displaces material and forms a stake, distributing the installation forces across multiple localized points rather than concentrating stress in a single annular region. This segmentation allows the fastener to achieve secure retention while minimizing overall warping of the workpiece.
Solution Approach 2:
The ribs are designed with specific geometric characteristics including tapered sides and curved top surfaces that create localized stress distribution patterns. The varying heights and profiles of the ribs allow for optimized material displacement in different radial zones, concentrating material flow control where needed while preserving flatness in other areas of the workpiece.
2Strength
If high staking forces are applied during installation, then the fastener achieves secure mechanical interlocking, but the workpiece material deforms and warps
Solution Approach 1:
The application of staking force is segmented across multiple ribs rather than applied as a single concentrated force. Each rib applies localized force to displace and stake material independently, achieving the required mechanical interlocking and joint strength while distributing the deformation across multiple small regions rather than causing overall workpiece warping.
Solution Approach 2:
The ribs feature curved top surfaces and tapered geometries that facilitate progressive material displacement during installation. The curved surfaces guide material flow in a controlled manner, allowing high staking forces to be applied while maintaining more uniform stress distribution and reducing sudden localized deformations that would cause warping.
3Ease of manufacture
If the clinch fastener design is simplified, then manufacturing cost decreases, but the fastener cannot provide uniform stress distribution
Solution Approach 1:
Rather than using complex continuous annular ribs or intricate head geometries, the design segments the stress distribution function into a small number of discrete, simple ribs. These ribs can be efficiently formed using conventional stamping or extrusion processes, maintaining ease of manufacture while achieving uniform stress distribution through their strategic placement and geometric profiles.
Solution Approach 2:
The rib geometry includes specific parameters such as tapered side angles, curved top surface radii, and varying heights that are optimized to control material displacement. By carefully selecting these geometric parameters, the design achieves uniform stress distribution and minimized warping while maintaining compatibility with standard manufacturing processes for forming the rib features.
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
This design reduces warping and distortion of workpieces, ensures the fastener remains perpendicular, and enhances the joint's integrity by evenly distributing stress, allowing for higher staking forces and thinner material usage without deformation.
Implementation Method 1
the clinch fastener displaces the host material around the mounting hole, causing the host material to cold flow into an annular recess or undercut in the clinch fastener
Data Source
AI summary
A clinch fastener includes a shaft defining a central axis and a head having an outer periphery cooperating with the shaft. A plurality of ribs disposed under the head to engage a workpiece. The plurality of ribs extending radially outward in a direction from a displacement collar positioned proximate the central axis of the clinch fastener to the outer periphery of the head. Each of the plurality of ribs includes multiple sections forming at least a sidewall and a parametric profile for each rib. The clinch fastener includes a retaining ring cooperating with the shaft and a retaining groove cooperating with the shaft positioned between the displacement collar and retaining ring. The plurality of ribs and displacement collar are configured to radially displace workplace material into the retaining groove and diffuse stress within the workpiece material when the fastener is secured to the workpiece.