Rotary Friction Joining via Void-Filled Metal for Structural Steel
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Solution Overview
Problem
Conventional friction welding methods are inefficient for joining large-scale steel members like columns and beams in architectural steel structures, requiring significant pressing force and complex mechanisms, and often result in unnecessary burrs and defects.
Innovation Solution
A rotational friction joining method using a joining metal inserted into a void between steel members, where friction generates heat to melt the metal, which is then filled into the gap and solidified to integrate the members, reducing the need for large pressing forces and complex mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional friction welding method is used to join large-scale steel members, then joining strength can be achieved, but large pressing force and complex mechanisms are required
Solution Approach 1:
The invention divides the joining process into two distinct phases: first, the joining metal is rotated against one steel member to create a friction surface and molten metal; second, the joining metal is pressed against the other steel member to complete the joint. This segmentation allows each phase to use optimized, simpler mechanisms rather than requiring both high rotation and high pressing force simultaneously
Solution Approach 2:
The joining metal is pre-rotated against the first steel member to generate friction heat and molten metal before the pressing operation. This preliminary action prepares the joining interface in advance, so that when pressing occurs, the molten metal is already available to flow into the gap and bond the members, eliminating the need for simultaneous rotation and pressing
2Strength
If conventional friction welding method is used, then steel members can be joined, but significant pressing force is required
Solution Approach 1:
The friction heating and molten metal generation are performed in advance during the rotation phase, before pressing begins. This ensures that when pressing force is applied, the joining interface is already prepared with molten metal ready to flow, maximizing bonding efficiency with reduced pressing force requirements
Solution Approach 2:
The invention changes the sequence and magnitude of process parameters: rotation speed is high during the heating phase but pressing force is low; then pressing force increases while rotation stops. This dynamic parameter change allows efficient joining without requiring simultaneously high values of both rotation and pressing force
3Strength
If conventional friction welding method is used, then joining can be achieved, but burrs are generated and material is wasted
Solution Approach 1:
The joining metal acts as an intermediary material that facilitates the joining process. It is selectively melted and transferred to the gap between steel members, filling voids and creating bonds without generating excessive burrs. The intermediary joining metal controls material flow and reduces waste compared to direct friction welding of the steel members themselves
4Strength
If conventional friction welding method is used, then steel members can be joined, but the mechanism is not portable and is complex
Solution Approach 1:
The joining operation is segmented into rotation-only and pressing-only phases, allowing the use of simpler, lighter mechanisms for each phase. The rotation mechanism does not need to support high pressing forces, and the pressing mechanism does not need to provide rotation, enabling portability and ease of operation while maintaining joining strength
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 method allows for efficient joining of large-scale steel members with a portable, simple mechanism, minimizing energy consumption and avoiding unnecessary burrs, while enhancing bonding strength and operational ease.
Implementation Method 1
friction being generated by rotating the joining metal around a rotating axis with a contact portion between a tip of the joining metal and the bottom of the void under pressing force
Implementation Method 2
molten metal being generated by melting material structure near the contact portion by utilizing frictional heat from the friction
Implementation Method 3
said liquefied molten metal being filled into a gap between said peripheral surface of said joining metal and said peripheral surface of said void by utilizing pressing force and rotational motion generated at the tip of said joining metal
Implementation Method 4
subsequently, rotational movement being stopped to have said molten metal be solidified and be integrated with structure near said gap, thus joining said first steel member and said second steel member
Data Source
AI summary
A void having a side peripheral surface and a bottom part is machined in a rotationally symmetrical shape spanning the end surface of a first steel member and the end surface of a second steel member; in a state in which a pressing force is applied to a contact area between the tip part of a joining metal and the bottom part of the void, the joining metal is rotated around a rotation axis and friction is created; the material structure around a rotational friction surface is joined using friction heat caused by the friction and molten metal is generated; a gap between a side peripheral surface of the joining metal and the side peripheral surface of the void is filled with the liquefied molten metal; and the first steel member and the second steel member are joined via the joining metal through integration with the structure near the gap.