Rivet Pressing Surface Roughness to Prevent Joint Clearance
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Solution Overview
Problem
Existing riveting methods cause excessive plastic deformation of the rivet's shaft portion in the radial direction, leading to clearance formation between the shaft and the through-hole, which degrades the fatigue strength of the fastened part.
Innovation Solution
A riveting device and method that utilize a riveting member with a flat pressurizing surface and surface roughening treatment to prevent excessive plastic deformation of the rivet's shaft portion, ensuring proper fit and maintaining fatigue strength by controlling the pressurizing force and surface roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a smooth die surface is used to plastically deform the rivet, then the rivet tail end is excessively enlarged in the radial direction, but this causes clearance formation between the shaft portion and through-hole, degrading fatigue strength
Solution Approach 1:
The invention changes the surface roughness parameter of the die from smooth (conventional) to rough (specifically, Ra value of 3.2μm or more). This parameter change prevents excessive radial enlargement of the rivet tail end during plastic deformation, thereby avoiding clearance formation between the shaft portion and through-hole, thus maintaining fatigue strength of the fastened part.
2Strength
If excessive plastic deformation force is applied to the rivet, then the rivet is fully deformed to secure members, but the shaft portion enlargement becomes excessively small, generating clearance and degrading fatigue strength
Solution Approach 1:
The invention changes the surface roughness parameter of the die to control the distribution of plastic deformation. The rough surface (Ra ≥ 3.2μm) creates localized deformation zones that prevent excessive radial enlargement of the tail end while ensuring adequate deformation of the shaft portion within the through-hole, thus maintaining both securing strength and fatigue strength.
3Shape
If the rivet tail end is excessively enlarged in radial direction, then the die surface contacts well, but the shaft portion accommodation in through-hole becomes insufficient, creating clearance
Solution Approach 1:
The invention changes the surface roughness parameter of the die to control the radial enlargement distribution. The rough surface (Ra ≥ 3.2μm) restricts excessive tail end enlargement while ensuring proper shaft portion fit within the through-hole, achieving both adequate shape deformation and precise dimensional control.
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
Prevents excessive plastic deformation and clearance formation, maintaining the fatigue strength of the fastened parts by curbing radial enlargement of the rivet's shaft portion, thus enhancing the structural integrity.
Implementation Method 1
a pressurizing mechanism that generates a pressurizing force of causing a distance between the first riveting member and the second riveting member along the axial line to decrease and plastically deforms the rivet
Implementation Method 2
a surface roughening treatment is performed on the pressurizing surface
Data Source
AI summary
Provided is a riveting device that deforms a rivet inserted into a through-hole formed in a plurality of plate-shaped members disposed in a superimposed state and secures the plurality of plate-shaped members, the riveting device including: an upper anvil that is disposed in a state in which the upper anvil faces an end surface of a head of the rivet; a lower anvil that is disposed in a state in which the lower anvil faces an end surface of a shaft portion 210 of the rivet; and a pressurizing mechanism that generates a pressurizing force of causing a distance between the upper anvil and the lower anvil along an axial line to decrease and plastically deforms the rivet, in which the pressurizing surface of the lower anvil is formed into a flat shape that perpendicularly intersects the axial line, and a surface roughening treatment is performed on the pressurizing surface.