Double-Shouldered Friction Stir Welding Tool
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Solution Overview
Problem
Current double-shouldered welding devices for friction stir welding face challenges in maintaining consistent joint thickness and quality due to variations in material thickness, as constant force control leads to excessive compression and material displacement, while spacing control struggles to accommodate slight thickness variations without requiring excessive or insufficient forces.
Innovation Solution
The implementation of a double-shouldered welding device with concentric rings, where the internal ring compresses the material and the external ring acts as a stop to limit sinking, allowing for controlled compression and maintaining constant force control regardless of material thickness, thereby compensating for geometric imperfections and thickness variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If constant force control is applied between the two shoulders, then the operation is easier to use, but the welded joint thickness becomes inconsistent and material collapses occur
Solution Approach 1:
The patent changes the physical parameter of the shoulder by introducing a stepped configuration with two distinct levels. The first shoulder level contacts the workpiece surface while the second shoulder level is positioned at a different height to control compression. This geometric parameter change allows constant force control to be applied while maintaining consistent joint thickness, as the stepped structure prevents excessive material compression that would otherwise occur with a single-shoulder design.
Solution Approach 2:
The shoulder is segmented into two distinct levels or steps rather than being a single continuous surface. This segmentation allows different portions of the shoulder to perform different functions: the first level provides surface contact and the second level controls compression depth. By dividing the shoulder into segments at different heights, the system achieves both ease of operation through force control and precision in joint thickness maintenance.
2Manufacturing precision
If spacing control is applied between the two shoulders, then the joint thickness is controlled, but the device requires variable forces that are too high or insufficient
Solution Approach 1:
The stepped shoulder design changes the geometric parameters of the tool to accommodate force variations while maintaining spacing control. The two-level shoulder structure allows the device to work with dimensional control (spacing) while the stepped configuration automatically adjusts the effective compression area, enabling the system to handle thickness variations without requiring excessive or insufficient forces.
3Temperature
If the working temperature increases during welding, then the material resistance decreases, but excessive compression occurs causing material discharge
Solution Approach 1:
As temperature increases and material resistance decreases during welding, the stepped shoulder configuration prevents excessive compression by providing a geometric constraint. The second shoulder level acts as a stop that limits how far the material can be compressed, preventing material discharge even as thermal softening occurs. This geometric parameter change compensates for the decreasing material resistance at elevated temperatures.
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 solution enables consistent and high-quality welding by controlling compression and preventing material displacement, ensuring reliable joint thickness and quality across varying material thicknesses, even with constant force control, and preventing overheating by limiting the amount of material stirred.
Implementation Method 1
a stir pawn designed to pass through the material to be welded and to be stirred as the welding device is advanced... The double-shouldered welding device makes it possible to create a heating of the two sides of the welded joint
Data Source
AI summary
The invention relates to a double shouldered welding device for the friction stir welding of parts, in which at least one shoulder has two concentric rings providing two plane concentric bearing surfaces, the rings being arranged so that the smaller-diameter ring is capable of compressing the stirred material of the parts to be welded during advance of the welding device and so that the larger-diameter ring is capable of forming a sink-in stop for the smaller-diameter ring. The invention also relates to a method of friction stir welding by means of the welding device according to the invention, in which said device is force-driven.