Friction Stir Spot Welding Plunging Force for Serial Heat Buildup
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Solution Overview
Problem
In friction stir spot welding, serial spots welding degrades the external appearance of welded objects due to heat accumulation in the welding tool, causing material softening and improper plasticization, leading to defects like underfill in the welded regions.
Innovation Solution
A friction stir spot welding device with a temperature detector and controller that adjusts the plunging force, rotational speed, or actuation time of the tool based on the detected temperature of the tool between welding steps to maintain optimal welding conditions, preventing excessive material softening and flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If serial spots welding is performed continuously, then productivity is improved, but heat accumulates in the welding tool causing material softening and degradation of welding quality
Solution Approach 1:
The patent implements periodic cooling action between welding steps. The controller stops the welding process intermittently to allow heat dissipation from the tool, creating a periodic cycle of welding and cooling. This prevents continuous heat accumulation while maintaining overall productivity, resolving the contradiction between fast serial welding and quality maintenance.
Solution Approach 2:
The patent dynamically changes the plunging force parameter based on detected tool temperature. When temperature exceeds the reference value, the controller reduces the plunging force applied by the tool to the workpiece. This parameter adjustment compensates for heat-induced material softening, maintaining welding quality despite continuous operation.
2Reliability
If the plunging force is increased to maintain welding quality, then welding quality is improved, but heat accumulation in the tool is accelerated
Solution Approach 1:
The patent employs a feedback control mechanism where a temperature detector continuously monitors tool temperature and feeds this information to the controller. The controller compares the detected temperature with a reference value and adjusts the plunging force accordingly. This closed-loop feedback system maintains welding quality while preventing excessive heat accumulation by reducing force when temperature rises.
3Reliability
If the tool temperature is monitored and adjusted, then welding quality is maintained, but device complexity increases
Solution Approach 1:
The patent implements a self-regulating system where the welding process automatically adjusts based on temperature feedback. The controller autonomously modifies plunging force parameters without requiring external intervention or complex manual control mechanisms. This self-service approach maintains welding quality consistency while minimizing the added complexity through automated rather than manual 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
This approach ensures a good welding quality by preventing material flow to the clamp member, thus maintaining a consistent and high-quality external appearance in serial spots welding.
Implementation Method 1
a temperature detector which detects a temperature of the tool
Implementation Method 2
a friction stir spot welding device which welds an object to be welded, by softening the object by friction heat and by stirring the object
Data Source
AI summary
A friction stir spot welding device which welds an object to be welded, by softening the object by friction heat and by stirring the object, has a tool with a cylindrical shape, the tool being rotatable around an axis thereof, advanceable along a direction of the axis, and retractable along the direction of the axis, a temperature detector which detects a temperature of the tool when a welding step for the object starts, and a controller configured to compare the temperature of the tool which is detected by the temperature detector to a predetermined reference temperature to set a plunging force applied by the tool to press the object.