Automated Semi-Tubular Riveting for Crack-Free Tail Flaring
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Manual installation of semi-tubular fastener rivets in composite structures is labor-intensive, prone to errors, and increases manufacturing costs due to the need for multiple tools and processes, leading to potential damage and increased cycle time.
Innovation Solution
An automated rivet apparatus with a numerical control drilling and riveting machine that includes a lower and upper head with drill spindles and anvils, controlled by a controller to accurately drill, countersink, and flare semi-tubular fastener rivets, eliminating the need for manual tools and ensuring high-quality flaring without cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If manual installation methods are used with multiple individual tools (drills, countersinks, gauges, squeeze devices), then the installation process can be completed, but the installation cycle time increases significantly (7 minutes or more per rivet) and labor costs increase
Solution Approach 1:
The patent combines multiple individual installation tools and processes (drilling, countersinking, gauging, squeezing) into a single integrated automated rivet installer apparatus. This merging eliminates the need to switch between multiple manual tools, significantly reducing installation cycle time while maintaining installation quality.
Solution Approach 2:
The patent replaces manual mechanical operations with an automated numerical control system that coordinates drilling, countersinking, and squeezing operations. This substitution eliminates manual labor and the time associated with manual tool handling, while the automated system manages the complexity of multiple operations through programmable control.
2Manufacturing precision
If manual flaring operations are performed on the tail portion of hollow-ended rivets, then the rivet can be installed, but the flaring quality is difficult to maintain and cracked flared tail portions may occur
Solution Approach 1:
The patent incorporates a load cell that provides real-time feedback on the squeezing force applied to the rivet tail portion. This feedback mechanism allows the numerical control system to precisely control the flaring process, maintaining consistent flaring quality and preventing excessive force that could cause cracking.
Solution Approach 2:
The patent replaces manual flaring operations with an automated squeezing mechanism controlled by numerical control. This substitution eliminates the variability and skill dependency of manual flaring, ensuring consistent flaring quality and reducing the risk of cracked tail portions through precise, repeatable force application.
3Strength
If solid rivets are installed in composite structures, then fastening can be achieved, but radial expansion of the rivet shank may crack or delaminate the composite fibers, decreasing strength
Solution Approach 1:
The patent changes the rivet design parameter from solid shank to hollow-ended shank. This parameter change allows the rivet to be installed in composite structures without radial expansion that would damage the composite fibers, while still achieving the necessary fastening strength through the hollow-ended design that flares at the tail portion.
4Productivity
If automated rivet installation is implemented, then installation cycle time is reduced and productivity increases, but the device complexity and initial cost increase
Solution Approach 1:
The patent designs the automated rivet installer as a multi-functional apparatus that performs drilling, countersinking, gauging, and squeezing operations within a single integrated system. This universality reduces the need for multiple separate machines or tool changes, making the automated system more cost-effective and manageable despite the increased automation level.
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 automated system significantly reduces installation cycle time, minimizes errors, and enhances the quality of flaring, thereby decreasing manufacturing costs and improving the strength of composite structures.
Implementation Method 1
The lower anvil is coupled to a load cell for providing a signal indicative of a level of the upset force applied by the lower anvil
Implementation Method 2
The lower anvil is movable and configured to apply an upset force to a tail portion of the semi-tubular fastener rivet
Data Source
AI summary
There is provided an automated rivet apparatus for installing a semi-tubular fastener rivet. The apparatus includes a numerical control (NC) drilling and riveting machine and a controller. The NC drilling and riveting machine includes a lower head having a lower pressure bushing, a lower drill spindle, and a lower anvil to apply an upset force to a tail portion of the semi-tubular fastener rivet. The NC drilling and riveting machine further includes an upper head having an upper pressure bushing, an upper drill spindle, and an upper anvil that holds the semi-tubular fastener rivet to insert the semi-tubular fastener rivet in a rivet-receiving hole. The lower drill spindle countersinks the rivet-receiving hole from a lower side of a workpiece. The controller directs movement of a nose of the lower anvil to apply the upset force and form a predetermined flare contour in the tail portion within a lower countersink.