Friction Stir Welding Tool Spacing for High-Melting Steel Joints
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Solution Overview
Problem
Conventional friction stir welding methods result in degraded joint properties when high-melting-point steel sheets are used due to rotating tool wear, leading to insufficient heat input and poor plastic flow.
Innovation Solution
Control the separation distance of rotating tools based on the load on them, satisfying specific relationships to maintain stable joint properties, using a friction stir welding device with a measurement and position adjustment mechanism to monitor and adjust the separation distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional friction stir welding is used with high-melting-point steel sheets, then welding process can be applied, but rotating tool wear occurs leading to degraded joint properties
Solution Approach 1:
The patent pre-heats the steel sheet surface to 50-150°C before friction stir welding begins. This preliminary heating action reduces the temperature differential between the tool and workpiece, minimizing thermal shock and tool wear during the welding process, thereby maintaining joint properties throughout the welding operation.
Solution Approach 2:
The patent changes the thermal parameter by pre-heating the steel sheet surface to a specific temperature range (50-150°C). This parameter change modifies the thermal conditions during welding, reducing tool wear and maintaining consistent joint properties even when welding high-melting-point steel sheets.
2Strength
If rotating tools are pressed against high-melting-point steel sheets, then joining can be achieved, but heat input becomes insufficient due to tool wear
Solution Approach 1:
The steel sheet surface is pre-heated to 50-150°C before welding begins. This preliminary action ensures that sufficient heat is already present in the workpiece, compensating for the reduced heat input from the rotating tool due to wear, thereby maintaining adequate thermal conditions for proper joining.
Solution Approach 2:
The pre-heating process acts as an intermediary that provides additional thermal energy to the system. This intermediary heat source compensates for the insufficient heat input from the worn rotating tool, ensuring adequate thermal conditions for maintaining joint strength.
3Manufacturing precision
If rotating tools are used on high-melting-point steel sheets, then welding can proceed, but plastic flow becomes poor due to tool wear
Solution Approach 1:
The steel sheet surface is pre-heated to 50-150°C before welding begins. This preliminary thermal preparation ensures that the material is sufficiently soft and pliable during welding, compensating for the reduced plasticizing capability of the worn rotating tool, thereby maintaining good plastic flow and manufacturing precision.
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
Stabilizes joint properties and produces high-quality joined members even with high-melting-point steel sheets by preventing tool wear and ensuring adequate heat input and plastic flow.
Implementation Method 1
The rotating tools are then pressed against the front surface and the back surface of the material to be joined, and are moved in a joining direction while being rotated. This allows the metal sheets to be softened by the frictional heat between the rotating tools and the material to be joined
Data Source
Figure 1
AI summary
A friction stir welding method is provided that makes it possible to stably obtain good joint properties at a joined portion even when high-melting-point steel sheets are used as material to be joined. A defined relationship is satisfied between a load on rotating tools and a separation distance of the rotating tools.