Friction Stir Spot Welding Stages for Sealant-Free Weld Regions
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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 resistance 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 main welding stroke to push out the sealant from the weld region in advance, preventing sealant interference with the subsequent welding process and ensuring both corrosion resistance and weld quality
Solution Approach 2:
The welding process is divided into multiple stages: initial pressing stage to remove sealant, and main welding stage to create the joint. This segmentation allows the sealant removal function to be performed separately before welding, resolving the conflict between maintaining sealant for corrosion protection and removing it for weld quality
2Reliability
If sealant is present during welding, then corrosion protection is maintained, but bond strength decreases due to sealant entry into plastic flow portion
Solution Approach 1:
The pin and shoulder advance beforehand to press and expel the sealant from the region where plastic flow will occur during welding, preventing sealant contamination of the bonding interface and ensuring high bond strength while preserving corrosion protection
3Manufacturing precision
If friction heat is generated to soften and push out sealant, then weld quality is improved, but energy consumption increases
Solution Approach 1:
The sealant is extracted or removed from the weld region through the pressing action of the pin and shoulder before welding, eliminating the need for prolonged friction heating and reducing overall energy consumption while maintaining weld quality
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 high-quality welds even in the presence of sealing materials, by effectively removing the sealant from the weld region and ensuring strong bonding between workpieces.
Implementation Method 1
The pressing of the weld region by the rotating pin and/or shoulder generates friction heat
Implementation Method 2
Transfer of the friction heat leads to melting and viscosity decrease of the sealant
Implementation Method 3
Transfer of the friction heat leads to melting and viscosity decrease of the sealant
Data Source
Figure 1
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AI summary
A friction stir spot welder includes a controller (51) configured to: (B) drive a rotary actuator (57) and an advancement/withdrawal actuator (53) to cause a pin (11) to press workpieces (60) while rotating; (C) after the pressing (B), drive the rotary actuator (57) and the advancement/withdrawal actuator (53) to cause the pin (11) and a shoulder (12) to press the workpieces (60) while rotating; and (D) after the pressing (C), drive the rotary actuator (57) and the advancement/withdrawal actuator (53) to cause the pin (11) and/or the shoulder (12) to plunge into a weld region of the workpieces (60) while rotating and stir the weld region to weld the workpieces (60) together.