Friction Stir Spot Welding Probe Structure for Burr Containment
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Solution Overview
Problem
Existing friction stir spot welding techniques result in burr formation that causes coating defects during electrocoating, necessitating an additional process to remove the burr, thereby increasing manufacturing costs.
Innovation Solution
A friction stir spot welding apparatus with a probe featuring a pin portion and an inner wall surface with a circumferential surface and a spaced surface, which restricts the burr from protruding outward, preventing coating defects and reducing manufacturing costs by eliminating the need for burr removal post-welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a gap portion is formed in the burr preventing portion to allow burr to protrude, then the burr can be contained without fusion, but the burr tip spreads outward causing coating defects
Solution Approach 1:
The inner wall surface is designed with different local characteristics: the circumferential surface provides a smooth guide for burr formation, while the spaced surface creates a controlled restriction zone. This local differentiation allows the burr to be contained and shaped properly without spreading outward, eliminating coating defects while maintaining the burr containment function
Solution Approach 2:
Instead of using a traditional burr preventing portion with a gap that allows burr to protrude and spread, the invention inverts the approach by using a spaced surface that actively restricts burr protrusion. The spaced surface is positioned outward from the circumferential surface to create a containment zone that prevents the burr tip from spreading outward, thus solving the coating quality issue
2Manufacturing precision
If a burr removal process is added after welding, then coating defects are reduced, but manufacturing costs increase
Solution Approach 1:
The spaced surface is integrated into the probe structure to perform preliminary action during the welding process itself. By restricting burr protrusion at the source during welding, the need for subsequent burr removal processes is eliminated, reducing manufacturing costs while ensuring coating quality
3Object-generated harmful factors
If the spaced surface is positioned outward from the circumferential surface, then burr protrusion is restricted, but the probe structure becomes more complex
Solution Approach 1:
The inner wall surface is segmented into two distinct surfaces: the circumferential surface and the spaced surface. This segmentation allows each surface to perform its specific function - the circumferential surface guides burr formation while the spaced surface restricts protrusion - without requiring a completely redesign of the probe structure, thus managing complexity through functional division
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 prevents burr protrusion and coating defects, allowing for direct electrocoating without additional processing steps, thereby reducing manufacturing costs and ensuring proper coating of friction-stir-welded workpieces.
Implementation Method 1
a friction stir spot welding apparatus configured to friction-stir-weld a plurality of materials including a plate-shaped first material (102) and a second material (104)
Implementation Method 2
an inner wall surface including: a circumferential surface protruding from the shoulder portion with a constant distance from the central axis; and a spaced surface provided continuously along with the circumferential surface and positioned outward from the circumferential surface
Data Source
AI summary
A friction stir spot welding apparatus is configured to friction-stir-weld a plurality of materials including a plate-shaped first material and a second material disposed in contact with a facing surface of the first material and comprises a probe rotatable about a central axis. The probe includes a pin portion protruding along the central axis from a bottom surface of a cylindrical shoulder portion. The probe also includes an inner wall surface including a circumferential surface protruding from the shoulder portion with a constant distance from the central axis and a spaced surface provided continuously along with the circumferential surface and positioned outward from the circumferential surface.