Punch Rivet with Perpendicular End for Composite Fastening
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Solution Overview
Problem
Existing methods for joining components made of fiber or fabric reinforced plastic are complex, expensive, and prone to fatigue, especially when combining these materials with metal or other composite materials, as they often require embedding fastening elements which disrupt the manufacturing process.
Innovation Solution
A punch rivet design with a ring surface at the free end perpendicular to the central axis and inner concave ring surface, along with ribs extending along the rivet section, allows for full penetration and formation of a high-strength rivet bead, facilitating a secure connection between components without the risk of the rivet being torn out, and enabling the creation of intermediate or finished products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If embedding fastening elements into composite material components is used, then components can be secured together, but the manufacturing process becomes complex and expensive
Solution Approach 1:
The invention extracts the fastening element from the composite material component itself. Instead of embedding fasteners into the composite parts, a separate punch rivet is used that pierces through pre-formed holes in the components. This separates the joining function from the structural components, simplifying their manufacturing while maintaining connection strength.
Solution Approach 2:
The punch rivet acts as an intermediary element between the composite material components. Rather than directly joining the components together or embedding fasteners within them, the punch rivet serves as a mediator that pierces through both components and creates mechanical interlocking, thereby simplifying the overall manufacturing process.
2Strength
If embedding fastening elements or reinforcement plates into composite material components is used, then components can be secured together, but the process sequence in manufacturing is disturbed
Solution Approach 1:
The invention applies preliminary action by creating pre-formed holes in the composite material components before the final assembly. These holes are prepared in advance during component manufacturing, allowing the punch rivet to be quickly inserted and set without disrupting the overall process sequence. This eliminates the need for additional embedding steps that would interrupt production flow.
3Ease of manufacture
If conventional punch rivet design with conical free end is used, then rivet section spreads in trumpet-like manner, but the rivet may be torn out of components or fatigue effects occur
Solution Approach 1:
The invention inverts the conventional conical geometry by making the free end of the rivet section substantially perpendicular to the longitudinal axis rather than converging inwardly. This inversion prevents the trumpet-like spreading that leads to rivet pull-out and fatigue, while the perpendicular geometry combined with transverse ribs creates effective mechanical interlocking for reliable joints.
4Strength
If rivet section is designed to fully pierce components, then high quality rivet joint is achieved, but rivet must be significantly longer than component stack thickness
Solution Approach 1:
The invention transitions from relying solely on longitudinal rivet penetration to incorporating transverse dimensional features. The perpendicular free end geometry combined with transverse ribs creates mechanical interlocking in the radial dimension, allowing effective joint formation without requiring excessive longitudinal rivet length to achieve full penetration and high joint 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
This method provides a high-quality, strong connection between components, reducing the risk of fatigue and allowing for efficient manufacturing processes, including the ability to create intermediate products that can be completed at different manufacturing locations, using materials like duroplastic matrix materials and sheet metal parts.
Implementation Method 1
a punch rivet has a flange of larger diameter, a rivet section of smaller diameter and a ring-like component contact surface at the side of the flange adjacent the rivet section and surrounding the rivet section. This surface is frequently a conical surface and is pressed during the pressing of the punch rivet into the two components
Implementation Method 2
The free end of the rivet section is formed by a conical surface which converges inwardly and in the direction of the flange. This leads to the rivet section being spread in trumpet-like manner during the pressing in of the punch rivet
Implementation Method 3
ribs extending parallel to the longitudinal axis are provided at the generally cylindrical outer surface of the rivet section
Implementation Method 4
The components are held together as a result of the wedge action of the trumpet-like shape of the rivet section, which is filled with material of the components
Data Source
Figure 1A~1B
Figure 1C
Figure 2A~2C
AI summary
A punch rivet (10) for fastening individual components (40, 42) to one another of which at least one component is formed by a workpiece of composite material, with the punch rivet having a flange (12) of larger diameter, a rivet section (14) of smaller diameter and a ring-like component contact surface (18) at the side of the flange adjacent the rivet section and surrounding the rivet section, with the rivet section having at its free end a ring surface (22) for the piercing of the two workpieces which stands at least substantially perpendicular to the central longitudinal axis of the punch rivet and an inner concave ring surface (26) which forms the transition from the end of the punch rivet into the hollow internal space of the rivet section. Ribs (30) extending parallel to the longitudinal axis are provided at the generally cylindrical outer surface of the rivet section and preferably extend up to the free end face of the rivet section. In addition, a method is claimed.