Friction Stirring Pressing Shaft with Segmented Rigidity
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Solution Overview
Problem
Friction stirring and joining processes often result in unevenness between joined members, leading to potential poor joining and reduced strength, and existing solutions either incur high costs or risk damage due to excessive joining pressure.
Innovation Solution
A friction stirring and joining apparatus with a load imparting section supported by first and second abutting portions that cancel out moments, a rotatable supporting portion to accommodate irregularities, and cooling and auxiliary pressing means to ensure consistent and effective joining without damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a strong joining pressure is applied by bending the pressing shaft to bring the pressurizing portion closer to the rotary tool, then the unevenness suppression is improved, but the pressing shaft may be damaged due to large moment
Solution Approach 1:
The pressing shaft is divided into multiple sections with different rigidity characteristics. The load imparting section has lower rigidity to absorb moments, while the proximal section has higher rigidity to prevent damage. This segmentation allows the structure to simultaneously suppress unevenness and prevent shaft damage by distributing mechanical stresses to appropriate sections.
Solution Approach 2:
Different sections of the pressing shaft are given different rigidity properties locally. The portion closer to the workpiece (load imparting section) is made more flexible to accommodate moment cancellation, while the portion closer to the support is made more rigid for structural integrity. This local differentiation of mechanical properties resolves the contradiction between needing flexibility for precision and rigidity for durability.
2Reliability
If a high-rigidity material is used for the pressing shaft to prevent damage, then the reliability is improved, but the cost increases significantly
Solution Approach 1:
Instead of using high-rigidity material throughout the entire pressing shaft, the shaft is segmented into sections with different rigidity requirements. Only the proximal section requiring high rigidity for damage prevention uses stronger material, while the load imparting section uses more cost-effective materials. This segmentation significantly reduces overall material costs while maintaining reliability where needed.
Solution Approach 2:
The rigidity parameter of the pressing shaft is varied along its length rather than being uniform. By changing the rigidity parameter locally to match the actual stress distribution and functional requirements, the design achieves the necessary reliability at minimal cost, avoiding the expense of using high-rigidity materials throughout the entire shaft.
3Force
If the pressing shaft is bent to bring the pressurizing portion closer to the tool, then the joining pressure effectiveness is improved, but a large moment is generated that may damage the shaft
Solution Approach 1:
The pressing shaft is segmented into a load imparting section and a proximal section with different rigidity characteristics. The load imparting section is positioned close to the tool for effective joining pressure, while the proximal section provides structural support. This segmentation allows the shaft to generate necessary moments for effective pressing without compromising overall reliability.
Solution Approach 2:
The proximal section of the pressing shaft acts as a counterbalancing element that resists the large moments generated by the bent load imparting section. This section provides the necessary structural counterweight to balance the moments, allowing the pressing shaft to maintain both effectiveness in joining pressure and reliability against moment-induced damage.
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 apparatus effectively suppresses unevenness, prevents damage, and enhances joining strength while controlling costs by canceling out moments and using cooling to manage heat, allowing for reliable and efficient friction stirring and joining.
Implementation Method 1
moments act on the load imparting section from the first abutting portion and the second abutting portion when the workpiece is pressed. However, since the load imparting section is provided with the first and second abutting portions so that the load imparting section is positioned therebetween, the moments generated in the first abutting portion and the second abutting portion, respectively are mutually cancelled out
Implementation Method 2
The friction stirring and joining makes a tool rotated in a state where a junction of the workpiece is pressurized by a predetermined pressurization force in a surface called a shoulder surface of the tool, thereby making frictional heat generated on a workpiece surface to soften the workpiece with this frictional heat to join the workpiece
Data Source
AI summary
A friction stirring and joining apparatus includes a tool holder; and pressing means provided ahead in a direction of joining by a tool held by the tool holder for pressing a junction surface of a workpiece. The pressing means includes a load imparting section that imparts a load toward the workpiece; a first abutting portion that is provided between the load imparting section and the tool held by the tool holder and abuts on the junction surface in the workpiece; a second abutting portion that is provided opposite the first abutting portion with respect to the load imparting section and abuts on the junction surface of the workpiece; and a supporting portion that is attached to the load imparting section and supports the first abutting portion and the second abutting portion.