Rivet Swaging Geometry to Prevent Clearance and Fatigue Loss
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Solution Overview
Problem
Existing swaging devices often result in excessive plastic deformation of rivets, leading to clearance formation between the rivet and the through-hole, which degrades the fatigue strength of the fastened portion.
Innovation Solution
A swaging device and method that utilize a first swaging member with a circular bottom surface and an inclined support surface, and a second swaging member with a pressurizing mechanism to plastically deform the rivet, ensuring the inclination angle of the support surface is smaller than the rivet's inclined surface, preventing excessive deformation and clearance formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the head portion of the rivet is plastically deformed to eliminate clearance between the rivet and through-hole, then the fatigue strength is improved, but excessive plastic deformation causes clearance to be generated again
Solution Approach 1:
The invention changes the geometric parameters of the swaging member by providing an inclined surface with a specific inclination angle (α) that is smaller than the inclination angle (β) of the rivet's inclined surface. This parameter relationship ensures controlled plastic deformation that eliminates clearance without causing excessive deformation that would generate new clearance
Solution Approach 2:
The inclined surface of the swaging member acts as an intermediary element between the pressurizing force and the rivet head. By mediating the deformation through this inclined surface with a carefully controlled angle, the system achieves precise control over the plastic deformation process, eliminating clearance while preventing excessive deformation
2Manufacturing precision
If the inclination angle of the support surface is made smaller than the inclination angle of the rivet's inclined surface, then excessive plastic deformation is prevented, but the complexity of the swaging device increases
Solution Approach 1:
The invention applies local quality by providing an inclined surface only at the specific location where it is needed - on the swaging member that contacts the rivet head. This localized feature with a specific inclination angle relationship provides precise deformation control at the critical interface without requiring complex mechanisms throughout the entire device
Solution Approach 2:
The inclined surface geometry introduces a curved or angled contact interface rather than a flat surface. This geometric feature allows for controlled progressive deformation as the swaging member contacts and deforms the rivet head, achieving precise deformation control through geometric design rather than complex mechanical control systems
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 effectively prevents excessive plastic deformation of the rivet head, maintaining the fatigue strength by ensuring a precise fit between the rivet and the through-hole, thus securing the plate-shaped members without clearance.
Implementation Method 1
a pressurizing mechanism that generates a pressurizing force of causing a distance between the first swaging member and the second swaging member along the axial line to decrease and plastically deforms the rivet
Data Source
AI summary
Provided is a swaging device including: an upper anvil that is disposed in a state in which the upper anvil faces an end surface of a head of a rivet; a lower anvil that is disposed in a state in which the lower anvil faces an end surface of a shaft portion 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 an end surface of the upper anvil includes a bottom surface that perpendicularly intersects the axial line X and a support surface that has a projecting length in a direction of the axial line with respect to the bottom surface gradually increasing from an inner circumferential side toward an outer circumferential side in the radial direction formed therein, and an inclination angle of the support surface is smaller than an inclination angle of the inclined surface of the rivet by a predetermined angle.