Friction Stir Spot Welding to Expel Sealant From the Weld Zone
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Solution Overview
Problem
Friction stir spot welding technologies face challenges in achieving high weld quality when sealing materials are present between workpieces, as they interfere with the welding process and can lead to reduced bond strength.
Innovation Solution
A friction stir spot welder with a pin and shoulder design that generates friction heat to soften and push out sealing materials, allowing for effective welding by rotating and pressing the workpieces with a controlled actuator system, reducing the viscosity of the sealant and minimizing its entry into the weld area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sealant is applied between workpieces to ensure corrosion resistance, then corrosion protection is improved, but weld quality deteriorates due to sealant interference with the welding process
Solution Approach 1:
The pin and shoulder perform preliminary pressing action before the actual welding plunge, which pushes the sealant out from the weld region in advance. This preliminary action prevents sealant contamination of the weld zone while maintaining the sealant's corrosion protection function between workpieces
Solution Approach 2:
The friction heat generated during the pressing phase, which would normally be considered a byproduct, is utilized to reduce the viscosity of the sealant. This viscosity reduction facilitates the sealant's expulsion from the weld region, converting the thermal effect into a beneficial mechanism for improving weld quality
2Manufacturing precision
If friction heat is generated to soften and push out sealant, then sealant removal is improved, but energy consumption increases
Solution Approach 1:
The pressing action with friction heat generation is applied partially - only for a predetermined time period before the welding plunge - rather than continuously throughout the entire welding process. This partial application of friction heating is sufficient to reduce sealant viscosity and facilitate its removal, while avoiding excessive energy consumption
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 system achieves high weld quality by effectively removing the sealing material from the weld area, reducing adhesion and ensuring strong bonds between workpieces, even in the presence of sealants.
Implementation Method 1
The pressing of the weld region by the rotating pin and/or shoulder generates friction heat. Transfer of the friction heat leads to melting and viscosity decrease of the sealant, facilitating pushing out of the sealant.
Implementation Method 2
Transfer of the friction heat leads to melting and viscosity decrease of the sealant, facilitating pushing out of the sealant.
Data Source
AI summary
A friction stir spot welder includes a controller configured to: drive a rotary actuator and an advancement/withdrawal actuator to cause a pin to press workpieces while rotating; after the pressing, drive the rotary actuator and the advancement/withdrawal actuator to cause the pin and a shoulder to press the workpieces while rotating; and after the pressing, drive the rotary actuator and the advancement/withdrawal actuator to cause the pin and/or the shoulder to plunge into a weld region of the workpieces while rotating and stir the weld region to weld the workpieces together.