Plastic Blind Rivet Shank Design for Uniform Deformation
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Solution Overview
Problem
Existing blind rivets face challenges in uniform deformation during setting, especially with asymmetrical material stresses, leading to non-uniform contact and limited holding forces, and are difficult to remove without damaging surrounding components.
Innovation Solution
Incorporating a guide element with radially inward projections or an annular bead in the rivet body to ensure centered deformation and enhanced locking mechanisms, allowing for uniform annular bead formation and easy removal by guiding the mandrel and relaxing the folded shank.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the rivet body is made of plastically deformable metal and dimensioned to project only a short distance, then the blind rivet can be pulled from the holes in the workpieces for removal, but the holding forces are very limited and strongly dependent on manufacturing-related dimensional variations
Solution Approach 1:
The shank is divided into multiple regions with different cross-sectional areas (first region with reduced cross-section, second region with further reduced cross-section), creating distinct functional zones that enable both strong holding and controlled deformation for removal
Solution Approach 2:
Different regions of the shank have different wall thicknesses and cross-sectional areas optimized for specific functions: the first region provides holding strength while the second region is designed for controlled deformation and removal
2Ease of manufacture
If the rivet body deforms non-uniformly during setting due to asymmetrical material stresses, then the setting process becomes unpredictable, but the deformation is non-uniform leading to non-uniform contact and limited holding forces
Solution Approach 1:
The shank features an asymmetric cross-sectional design with the second region having a smaller cross-section than the first region, creating predetermined deformation zones that guide uniform deformation despite asymmetrical material stresses from molding
Solution Approach 2:
The shank is pre-formed with specific geometric features (reduced cross-section regions) during manufacturing that predispose it to deform in a controlled, uniform manner during the setting process, compensating for asymmetrical residual stresses
3Ease of operation
If the blind rivet is designed for easy removal, then it can be pulled from the workpieces, but the holding forces during operation are reduced
Solution Approach 1:
The shank transitions from a rigid holding structure during installation to a controlled deformation state during removal, with the second region designed to deform preferentially to enable extraction while maintaining strength during the holding phase
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 uniform deformation of the rivet body during setting, enhancing holding forces and seal integrity while allowing for easy single-piece removal without damaging surrounding components, suitable for both manual and automated processes.
Implementation Method 1
the bore (14) in the rivet body (11) has, in the head section (20) of the shank (13), a guide element (31) by which the shank (13) is guided on the mandrel shank (34)
Implementation Method 2
enables uniform deformation of the rivet body during setting, enhancing holding forces and seal integrity
Implementation Method 3
allowing for easy single-piece removal without damaging surrounding components, suitable for both manual and automated processes
Data Source
AI summary
A blind rivet having a hollow rivet body made of plastic, an elongated shank with a bore, a head at one end of the shank and a foot end on the opposite end of the shank, and having, in the bore, a mandrel that has a mandrel shank with a drawing end and a mandrel head that acts on the foot end, the shank has a first region located between the head and the foot end, and has a second region with reduced cross-section and reduced wall thickness as compared to the first region. The regions arranged such that, as a result of a process in which the head is pressed against one side of a workpiece and the foot end is simultaneously drawn toward the other side of the workpiece with the aid of the mandrel, the wall of the shank forms a roll fold with an annular bead.