Self-Punching Fastener Structure for Secure Slug Retention
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Solution Overview
Problem
Conventional self-punching functional elements face challenges in reliably securing punched slugs, which can lead to damage from loose slugs under heavy loads or vibrations, and require time-consuming and costly removal processes.
Innovation Solution
A self-punching functional element with a head part and a punching section featuring a circumferential punching edge and a slug securing elevation, which radially projects inward to securely hold the slug within a cavity, ensuring reliable slug retention through frictional and form-fitting mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the slug is left in the punched section without securing features, then the element structure remains simple, but the slug becomes loose under heavy loads or vibrations causing damage
Solution Approach 1:
The inner wall of the punching section is equipped with slug-protection elevations (ribs) that project radially inward into the cavity. These elevations are located only in specific regions where slug retention is needed, rather than throughout the entire structure. This local addition provides reliable slug securing while maintaining overall structural simplicity and minimizing impact on the element's basic design.
2Productivity
If conventional self-punching elements are used without slug securing features, then the manufacturing process is simpler and faster, but slug removal requires time-consuming and costly processes
Solution Approach 1:
The slug-protection elevations are integrated directly into the element structure during manufacturing, extracted as a single component. This integration means the slug retention feature is built-in rather than added separately, maintaining manufacturing efficiency while eliminating the need for complex post-manufacturing slug removal processes.
3Reliability
If the slug-protection elevation is added to secure the slug, then slug retention is improved, but the element manufacturing complexity increases
Solution Approach 1:
The slug-protection elevations are positioned only in specific regions of the inner wall where they are most effective for slug retention. This localized approach provides the necessary reliability improvement while minimizing the addition of structural complexity compared to a complete redesign of the element.
Data Source
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AI summary
The present invention relates to a self-punching functional element designed for punching into a workpiece (36), in particular a sheet metal part. It comprises a head section (12) forming a flange with a contact surface (14) for bearing against the workpiece (36) and a punching section (16) extending away from the head section (12), in particular from the contact surface (14), which is arranged, in particular, coaxially to a central longitudinal axis (A) of the functional element. The punching section (16) has a circumferential punching edge (22) at its free end for punching through the workpiece (36) and surrounds a cavity (20) in the circumferential direction, which has an opening (24) defined by the punching edge (22).An inner wall (18i) of the punched section (16) facing the cavity (20) has at least one slug-protection projection (26) extending radially inwards into the cavity (20), in particular wherein the projection (26) has the form of a rib extending in the axial direction.