Self-Punching Fastener Head Structure for Torque-Resistant Sheet Joints
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Solution Overview
Problem
Self-punching functional elements used in sheet metal parts face challenges in withstanding high pressing-out forces, tensile forces, and torques, requiring improved fastening mechanisms to ensure secure attachment and resistance against deformation.
Innovation Solution
The design incorporates a head part with a contact surface and a boundary section that form a ring space with oblique inner and outer walls, creating undercuts for a form fit with the workpiece, along with features like ribs and bases to enhance resistance against rotation and ensure a secure connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If self-punching functional elements are used to fasten sheet metal parts, then pre-punching is eliminated and cost advantages are achieved, but the elements face challenges in withstanding high pressing-out forces and tensile forces
Solution Approach 1:
The functional element is divided into distinct structural zones: a head part with flange, a punching section with oblique outer wall, and an inner wall with undercut. This segmentation allows each zone to perform its specific function - the head part provides bearing surface, the punching section creates the hole, and the undercut section provides form fit and resistance to pressing-out forces.
Solution Approach 2:
The outer wall of the punching section is designed with an oblique arrangement relative to the longitudinal axis, creating an asymmetric undercut structure. This asymmetric design enables the element to effectively resist pressing-out forces by creating a mechanical interlock with the workpiece material, while maintaining the self-punching capability.
2Ease of operation
If self-punching functional elements are used, then fastening process is simplified, but the elements struggle to withstand high torques and tensile forces
Solution Approach 1:
The element is designed with pre-formed undercut structures in the inner and outer walls before the fastening process. These undercuts are prepared in advance to receive and mechanically interlock with the workpiece material during pressing, enabling the element to withstand torques and tensile forces without requiring additional reinforcement steps.
Solution Approach 2:
The geometric parameters of the inner and outer walls are optimized to create effective undercuts. The oblique arrangement and specific angles of these walls are carefully designed to maximize the mechanical interlock strength, enabling the element to resist high torques while maintaining a simple fastening process.
3Ease of manufacture
If the head part has a simple design, then manufacturing is easier, but the connection security against pressing out and pulling out is reduced
Solution Approach 1:
The solution moves from a two-dimensional flat head design to a three-dimensional structure with undercut features in the inner and outer walls. These vertical-dimensional undercuts create mechanical interlocking with the workpiece material, significantly enhancing connection security against pressing out and pulling out forces while maintaining manufacturing feasibility.
Data Source
AI summary
The present invention relates to a self-punching functional element that is configured for punching into a workpiece, comprising a head part forming a flange; and a punching section that extends away from the head part, and that has a peripheral punching edge, wherein the head part has a contact surface for contact with the workpiece, said contact surface at least sectionally surrounding the punching section at a radial outer side, and a boundary section that at least sectionally bounds the contact surface at the radial outer side and that extends away from the contact surface in the same direction as the punching section. The invention further relates to a component assembly comprising a self-punching functional element, and a workpiece.