Consumable Hollow Stirring Bar for Full-Penetration Friction Stir Welding
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Solution Overview
Problem
Conventional friction stir welding tools suffer from wear, fracture, and high manufacturing costs, especially when welding high-melting-point materials, and often result in incomplete penetration due to mismatched tool pin lengths and workpiece thicknesses.
Innovation Solution
A friction stir welding apparatus and method using a low-cost consumable stirring bar made of the same or similar material as the welded workpiece, with a hollow cavity for forced cooling by a circulating coolant, allowing for full penetration and improved welding reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional non-consumable welding tool is used, then the tool can be reused multiple times, but the tool suffers from wear, fracture, and high manufacturing costs
Solution Approach 1:
The patent employs a consumable stirring pin made of the same or similar material as the workpiece, which is intentionally designed to be replaceable and relatively inexpensive. This disposable approach eliminates the wear and fracture problems of conventional tools while reducing manufacturing costs, as the simple material composition and straightforward structure make the stirring pin easy and cheap to produce.
Solution Approach 2:
The patent changes the material parameter of the welding tool from high-strength refractory materials to match the workpiece material properties. This parameter change allows the tool to be made from readily available, low-cost materials while maintaining compatibility with the workpiece for effective welding.
2Manufacturing precision
If the tool pin length is extended to match thicker workpieces, then full penetration can be achieved, but the tool becomes more prone to fracture and wear
Solution Approach 1:
By accepting the stirring pin as a consumable component, the patent can optimize its length for full penetration without compromising on structural strength. The stirring pin is designed with sufficient length to penetrate thick workpieces completely, and its consumable nature means it can be replaced rather than requiring complex reinforcement to prevent fracture.
Solution Approach 2:
The stirring pin is made from the same or similar material as the workpiece, creating material homogeneity between tool and workpiece. This homogeneity ensures compatible mechanical properties, allowing the stirring pin to effectively stir and penetrate the workpiece material without creating stress concentration points that would lead to premature failure.
3Temperature
If a refractory material tool is used for high-melting-point materials, then the tool can withstand high temperatures, but the manufacturing cost increases and processing difficulty increases
Solution Approach 1:
The patent fundamentally changes the temperature resistance parameter approach by matching the stirring pin material to the workpiece material. Instead of using high-temperature refractory materials, the stirring pin is made from the same or similar material as the workpiece, which naturally has compatible temperature resistance properties for the specific application.
Solution Approach 2:
By using homogeneous material composition between the stirring pin and workpiece, the patent eliminates the need for specialized refractory materials. The workpiece material itself provides the necessary temperature resistance, simplifying manufacturing while maintaining performance.
4Productivity
If the stirring pin rotates at high speed to generate friction heat, then the welding process is efficient, but the stirring pin experiences severe wear and fracture
Solution Approach 1:
The patent accepts that high-speed rotation will cause wear and fracture, but designs the stirring pin as a consumable component that can be easily replaced. This approach maintains high welding efficiency through high-speed operation while eliminating the reliability concern through the disposable design.
Solution Approach 2:
The homogeneous material composition between stirring pin and workpiece ensures that wear occurs uniformly and predictably. The stirring pin material matches the workpiece material, creating consistent friction characteristics that maintain welding efficiency while the stirring pin gradually consumes in a controlled manner.
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 use of a consumable stirring bar with forced cooling enhances welding reliability, prevents tool wear and fracture, and ensures full penetration regardless of workpiece thickness, thereby improving mechanical performance and efficiency of the welding joint.
Implementation Method 1
a cooling medium is introduced into the center of the stirring bar to apply forced cooling
Implementation Method 2
a cooling medium is introduced into the center of the stirring bar to apply forced cooling
Implementation Method 3
the welding tool generates friction with the to-be-welded workpiece material thereby heating and softening the material
Implementation Method 4
The friction stir welding uses friction heat and plastic deformation heat as welding heat sources
Data Source
AI summary
A friction stir welding apparatus includes a hollow stirring bar, a clamping mechanism, a welding machine main shaft, a supporting carriage, a cooling system, a coolant tank, a guide rail, and pipes. The cooling system is connected with the outer surface of the welding machine main shaft through two sealed bearings; the clamping mechanism is connected with the welding machine main shaft; the clamping mechanism clamps one end of the stirring bar; the other end of the stirring bar penetrates the welded workpiece to engage with the supporting carriage; the guide rail is installed below the supporting carriage; the pipes includes a first pipe and a second pipe; one end of the first pipe is connected with the outlet of the tank, and the other end of the first pipe is connected with the inlet of the cooling system. The second pipe returns the cooling medium to the tank.