Friction Stir Welding Pin Tip Geometry for Higher Speed Stability
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Solution Overview
Problem
Friction pins in friction stir welding systems often break due to local material variations, such as hardness changes in cast materials, leading to operational inefficiencies and reduced tool service life.
Innovation Solution
A device and method that incorporate a tool drive with a conical tool dome, a tool shoe with a smoothing and compacting surface, and an annular friction surface surrounding a conveying screw, which heats the materials to increase welding speed and stability, while a lifting device with rolling rollers addresses burrs and unevennesses, optimizing the breakaway edge and reducing internal friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the welding pin operates through local material variations with high contact pressure, then material transport is achieved, but the pin breaks due to hardness changes in cast materials
Solution Approach 1:
The patent changes the geometric parameters of the pin tip by introducing an annular friction surface at a specific distance from the pin tip, and modifies the conveying screw thread direction to run counter to the pin tip thread. These parameter changes optimize material transport while reducing stress concentrations that cause pin breakage
Solution Approach 2:
The annular friction surface performs preliminary heating and material softening before the main conveying action occurs. This preliminary action reduces the force required for material transport, preventing pin breakage during operation
2Productivity
If the welding speed is increased, then productivity improves, but pin breakage occurs more frequently due to increased stresses
Solution Approach 1:
The patent replaces pure mechanical conveying with a combination of thermal softening via the annular friction surface and modified screw conveying. This substitution reduces mechanical stresses on the pin, enabling higher welding speeds without increasing pin breakage frequency
3Speed
If the contact pressure is increased to improve material transport, then welding speed increases, but self-heating of the tool increases
Solution Approach 1:
The annular friction surface is positioned at a specific distance from the pin tip to create localized heating only where needed for material transport. This local quality approach heats only the immediate working zone rather than the entire tool, increasing welding speed while controlling overall tool temperature
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 solution enhances welding speed and tool service life by reducing contact pressure, minimizing self-heating, and effectively managing material transport, resulting in a more stable and efficient welding process.
Implementation Method 1
the annular friction surface (9) heats the parts (5) to be joined by friction and thus increases the speed of the welding operation
Implementation Method 2
a conveying screw (8) for the output of the material transport from the pin tip (10), the thread of which conveying screw runs counter to the thread of the pin tip (10)
Implementation Method 3
a lifting device (18) for the possible swiveling of a rolling-roller arm (17) into the region of the abutment edge (1) of the parts (5) to be joined, and in that the half radius (15) of the smoothing and compacting surface (11) adjoins the pin shank (6)
Data Source
AI summary
The invention relates to a device and method for increasing the speed and increasing the stability of the welding pin in friction stir welding with the following device features: a) a tool drive has a retaining flange for a cone-shaped tool cover with a union nut; b) an annular retaining ring surrounds a pin shank with a tool shoe secured to the diameter of the retaining ring, wherein the tool shoe has a smoothing and compressing surface in the region of the pin tip for smoothing the weld seam, wherein the pin shank has the width of the tool shoe; c) the pin tip has an annular friction surface which surrounds a screw conveyor for the output of material transport from the pin tip, which has a thread running in the opposite direction to the thread of the pin tip.