Friction Welding Load Control to Prevent Workpiece Bending
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Solution Overview
Problem
Friction welding often results in bending or buckling of workpieces due to improper compressive load and end surface irregularities, leading to defective parts and low manufacturing yield.
Innovation Solution
A friction welding method and apparatus that control the compressive load and relative rotation speed to prevent bending by ensuring the compressive load is below the bend-producing threshold and generating sufficient friction heat for plastic deformation, allowing for correction of end surface irregularities before increasing the load for accurate joining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If compressive load is increased to ensure proper friction welding, then welding quality improves, but workpiece bending or buckling occurs
Solution Approach 1:
The patent applies preliminary action by performing friction welding at a first, lower compressive load to correct end surface irregularities before applying the second, higher compressive load for final joining. This preliminary friction welding step prepares the workpiece ends by removing irregularities that would otherwise cause bending during high-load welding, thus preventing shape distortion while ensuring welding quality.
2Shape
If compressive load is kept low to prevent bending, then workpiece shape is maintained, but insufficient friction heat is generated for proper welding
Solution Approach 1:
The patent uses preliminary action by first applying a lower compressive load to generate friction heat and correct end surface irregularities, then subsequently applying a higher compressive load to generate sufficient friction heat for proper welding. This two-stage approach ensures both shape maintenance during the preliminary stage and adequate heat generation during the final welding stage.
Solution Approach 2:
The patent applies dynamics by varying the compressive load throughout the welding process rather than maintaining a constant load. The compressive load is dynamically adjusted from a first lower value during preliminary friction welding to a second higher value during final joining, allowing the system to adapt to different process requirements at different stages.
3Ease of manufacture
If end surface irregularities are present, then manufacturing is easier, but bending tendency increases during welding
Solution Approach 1:
The patent converts the harmful effect of end surface irregularities into a beneficial process feature. Rather than requiring perfect end surfaces, the method uses the irregularities to generate friction heat during preliminary welding, which actually helps correct the irregularities. This transforms what would normally be a defect into a useful mechanism for surface preparation and heat generation.
Solution Approach 2:
The patent applies preliminary action by performing a first friction welding pass specifically designed to correct end surface irregularities before the final welding pass. This preliminary step removes or reduces irregularities that would otherwise cause bending during high-load welding, thereby improving welding reliability while maintaining ease of manufacture.
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 method and apparatus effectively prevent bending and buckling, ensuring accurate joining of workpieces while maintaining a properly performed friction process, thereby improving manufacturing yield and part quality.
Implementation Method 1
end surfaces of any two such workpieces to be integrally joined might be made to engage in relative rotation while the end surfaces are in mutual contact as a compressive load is applied thereto so as to generate heat due to friction at a joint interface between the workpieces
Implementation Method 2
the compressive load and the relative rotation between the workpieces are such as will cause the heat due to friction which is generated between the workpiece end surfaces to be capable of causing plastic deformation between the workpiece end surfaces
Data Source
AI summary
A friction welding method comprises causing an end surface of a first workpiece and an end surface of a second workpiece to engage in relative rotation while the end surfaces are in mutual contact as a compressive load is applied thereto so as to generate heat due to friction at a joint interface between the workpieces, thereafter stopping the relative rotation of the workpieces, and then applying an upset process pressure to the workpieces. When the workpiece end surfaces are brought into mutual contact, a compressive load employed is less than a lower threshold of a bend-producing compressive load domain within which bending of the first workpiece and/or the second workpiece would occur but the compressive load and the relative rotational speed between the workpieces are such as will cause the heat due to friction to be capable of causing plastic deformation at workpiece end surface(s).