Expanding Rivet Assembly for One-Sided Play-Free Joining
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Solution Overview
Problem
Conventional expanding rivets require access from both sides for assembly and do not provide a play-free connection under nominal load, making them impractical for high-frequency applications like large assemblies such as antennas.
Innovation Solution
An expanding rivet connection system that allows one-sided assembly, featuring an expanding rivet body, a threaded part, an expanding rivet pin, and a clamping element, which enables pre-assembly of joining partners and prestressing to prevent play, using a spring element and spacers to compensate for thickness fluctuations and environmental stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional expansion rivets are used to create permanent connections, then force transmission is achieved through positive locking, but access from both sides is required for assembly
Solution Approach 1:
The expansion rivet is divided into two main parts: an insertion element with expansion jaws that fits into the workpiece, and a separate mandrel that is inserted afterward to trigger expansion. This segmentation allows the rivet body to be installed first through a single-sided hole, then the mandrel is inserted from the same side to activate expansion, eliminating the need for bilateral access while maintaining reliable force transmission through positive locking
Solution Approach 2:
The insertion element with expansion jaws is preliminarily positioned in the workpiece hole before the mandrel is inserted. The expansion jaws are pre-configured in a compressed state that allows easy insertion through the hole, and after positioning, the mandrel is inserted to trigger the expansion action. This preliminary positioning from one side followed by activation from the same side resolves the accessibility constraint
2Ease of operation
If expansion rivets are installed from one side only, then assembly is simplified, but the connection exhibits play within permissible force-bearing range
Solution Approach 1:
The expansion rivet transitions from a static pre-assembled state to a dynamic expansion state when the mandrel is inserted. The mandrel applies force to the expansion jaws, causing them to dynamically expand and press against the inner wall of the hole. This dynamic expansion process ensures full engagement with the workpiece, eliminating play and ensuring reliable connection stability under load while maintaining one-sided assembly simplicity
3Reliability
If conventional expansion rivets are used, then permanent connections are created, but backlash-free connection requires installation from both sides
Solution Approach 1:
The expansion action is shifted to occur along the longitudinal axis of the rivet rather than requiring lateral access. The mandrel inserts through the same hole from the same side, pushing the expansion jaws outward radially against the hole wall. This dimensional change in the expansion mechanism allows the jaws to expand symmetrically against the circular hole wall, achieving a backlash-free connection through single-sided access by utilizing the radial dimension for expansion while accessing only through the longitudinal dimension
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
Enables play-free connections between multiple joining partners, allowing for flexible assembly and maintaining the connection under thermal or mechanical stress, with the clamping element providing a controlled preload to prevent shifting and ensure stability.
Implementation Method 1
an expansion rivet pin (12) designed to be pressed into the expansion rivet body (110) through an opening (112) arranged in the expansion rivet (11) in order to protrude through the first joining partner (21)
Implementation Method 2
a clamping element (13) designed to be screwed onto the threaded portion (111) of the expansion rivet (11) in order to connect at least one further joining partner (23) to the first joining partner (21)
Implementation Method 3
using a spring element and spacers to compensate for thickness fluctuations and environmental stresses
Data Source
Figure 1~2
Figure 3~4
AI summary
A compression rivet connection (100) is provided for connecting at least two joining partners (21, 23), comprising a compression rivet (11), comprising a compression rivet body (110) formed such that it can be inserted into the first joining partner through recesses in the first joining partner, and a threaded part (111) formed such that it protrudes at least partially from the first joining partner after insertion, a compression rivet pin (12) designed to be pressed into the compression rivet body through an opening arranged in the compression rivet in order to protrude through the first joining partner, and a clamping element (13) designed to be screwed onto the threaded part of the compression rivet in order to connect at least one further joining partner to the first joining partner. Furthermore, an expansion rivet connection for joining at least three joining partners (21, 22, 23) and a method for assembling the expansion rivet connection are provided.