Self-Punching Functional Element for Slug-Free Thread Access
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Solution Overview
Problem
Existing self-punching fastening elements, such as rivet nuts, face issues with slug removal, which can damage the internal thread and require additional worksteps, increasing assembly effort and the risk of jamming.
Innovation Solution
A self-punching functional element with a head part and a rivet section featuring a first and second punching edge, where the second edge is set back to punch a hole in the slug, allowing for secure fastening by reshaping the rivet section to form an undercut, and a punching pilot to clamp the slug ring, ensuring the functional section's functionality with minimal assembly effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the slug is punched out very small to be led away by the internal thread, then the functional section can be accessed, but the tendency of the rivet section to tear is greatly increased
Solution Approach 1:
The punching process is segmented into two distinct stages: first punching the slug out of the workpiece, then punching a hole through the slug. This segmentation allows the slug to be divided into two parts (the punched-out slug and the slug ring remaining in the functional section), resolving the contradiction between accessing the functional section and maintaining rivet section integrity
Solution Approach 2:
A hole is preliminarily punched through the slug during the fastening process itself, before the functional section needs to be accessed. This preliminary action prevents the need for subsequent slug removal operations that could damage the internal thread, while the rivet section is already secured through reshaping
2Reliability
If a punch is used to expel the blocking slug by means of the internal thread, then the functional section can be accessed, but a further workstep is required
Solution Approach 1:
The functional element performs the slug hole-punching operation itself during the fastening process. The punching pilot with its second punching edge automatically punches a hole through the slug as the element is being set, eliminating the need for separate slug removal operations and enabling self-service functionality
Solution Approach 2:
The slug hole-punching operation is merged with the fastening operation. Both actions (fastening and creating access to the functional section) are performed in a single integrated process step, eliminating the need for separate worksteps and improving productivity
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 enables reliable fastening of the functional element to a workpiece with reduced assembly effort, ensuring the functional section's integrity and preventing slug-related issues, allowing for secure holding without additional worksteps.
Implementation Method 1
a first punching edge (21) for punching a slug out of the workpiece
Implementation Method 2
a second punching edge (23) for punching a hole into the slug
Implementation Method 3
reshaping the rivet section such that it forms an undercut acting in an axial direction and the functional element is thereby securely held at the workpiece
Implementation Method 4
a punching pilot to clamp the slug ring
Data Source
AI summary
A self-punching functional element serves for the fastening to a workpiece and comprises a head part that has an abutment surface for introducing a punching force directed in a punching direction into the functional element and a rivet section that extends away from the head part in the punching direction and that comprises a free end that is provided with a first punching edge for punching a slug out of the workpiece. The functional element further comprises a functional section that has a punching pilot that is radially surrounded by the rivet section, that extends away from the head part in the punching direction, and that has a second punching edge for punching a hole into the slug. The second punching edge is set back with respect to the first punching edge in the punching direction.