Hot Metal Friction Welding With Controlled Scale Thickness
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Solution Overview
Problem
Existing methods for welding hot metal products before hot rolling face challenges in achieving optimal coefficient of friction for efficient friction welding, leading to either excessive force requirements or inadequate temperature increase due to improper scale management, which affects the strength and stability of the welded joint.
Innovation Solution
The method involves adjusting the coefficient of friction by allowing a predetermined thickness of scale to form on the metal product ends before welding, within a specific range (0.1 to 1.5), by exposing the ends to ambient air or oxidizing gases for a controlled duration, ensuring effective friction welding under normal ambient conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the metal product ends are completely descaled before welding, then the welding surface purity is improved, but the coefficient of friction becomes too high requiring excessive welding forces
Solution Approach 1:
The patent applies local quality by creating a non-uniform scale distribution on the welding surface. Instead of complete descaling or uniform scaling, a specific scale thickness (0.1-1.5 mm) is maintained only in the friction contact zone, while other areas can be cleaner. This localized scale layer optimizes friction characteristics exactly where needed without affecting overall surface purity requirements.
Solution Approach 2:
The patent changes the physical parameter of the welding surface by introducing a controlled scale layer with specific thickness (0.1-1.5 mm). This parameter modification transforms the surface from a completely clean state (high purity but high friction) to an optimally scaled state (controlled purity with optimized friction coefficient), resolving the contradiction between surface cleanliness and friction management.
2Ease of operation
If a thick scale layer is applied on the metal product ends before welding, then the coefficient of friction is reduced facilitating relative movement, but the temperature increase during friction welding becomes insufficient
Solution Approach 1:
The patent precisely controls the scale layer thickness parameter within the range of 0.1-1.5 mm to optimize the friction coefficient. This parameter optimization ensures that the scale layer is thin enough to allow sufficient heat generation through friction while being thick enough to reduce the coefficient of friction and facilitate relative movement between the metal product ends.
3Force
If the metal product ends are exposed to ambient air for extended periods, then scale formation occurs reducing friction coefficient, but the time required for the welding process increases
Solution Approach 1:
The patent applies preliminary action by intentionally creating the scale layer through controlled exposure to ambient air or oxidizing gases before the friction welding process begins. This pre-scaling action ensures that the optimal scale thickness (0.1-1.5 mm) is achieved in advance, allowing the subsequent welding operation to proceed immediately with optimized friction characteristics without time loss during welding.
Solution Approach 2:
The patent uses strong oxidants (ambient air or oxidizing gases) to accelerate scale formation on the metal product ends. This accelerated oxidation process enables the desired scale thickness to be achieved quickly during a controlled exposure period, minimizing the time required while ensuring the friction coefficient is optimized for efficient welding.
4Manufacturing precision
If friction welding is performed under inert gas atmosphere, then scale formation is prevented maintaining surface purity, but the coefficient of friction becomes too high and welding forces increase
Solution Approach 1:
The patent applies local quality by creating a non-uniform scale distribution on the welding surface. Instead of complete descaling or uniform scaling, a specific scale thickness (0.1-1.5 mm) is maintained only in the friction contact zone, while other areas can be cleaner. This localized scale layer optimizes friction characteristics exactly where needed without affecting overall surface purity requirements.
Solution Approach 2:
The patent changes the physical parameter of the welding surface by introducing a controlled scale layer with specific thickness (0.1-1.5 mm). This parameter modification transforms the surface from a completely clean state (high purity but high friction) to an optimally scaled state (controlled purity with optimized friction coefficient), resolving the contradiction between surface cleanliness and friction management.
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 approach allows for better relative movement and temperature increase during friction welding, resulting in improved welding results with enhanced joint strength and reduced oscillating forces, while maintaining the process under standard atmospheric conditions without the need for inert gases.
Implementation Method 1
The two metal products are pressed against one another on their end faces to be connected and at the same time are moved, in particular oscillated, relative to one another. This creates high temperatures in the area of the friction surfaces and leads to welding of the respective ends.
Implementation Method 2
adjusting the coefficient of friction by after cropping but before welding a layer of scale with a thickness d predetermined in accordance with the coefficient of friction is specifically applied to the end face of the leading and/or lagging metal product or by allowing the layer of scale to form there in a targeted manner
Data Source
AI summary
The invention relates to a method for welding two hot metal products together, preferably for subsequent quasi-continuous hot rolling. According to the method, the metal products to be welded together are first cropped at the end faces thereof to be joined, in order to obtain flat abutting surfaces that are additionally initially still free of scale at the time of the cropping. In order to enable the friction welding of the two metal products to one another at the cropped end faces thereof without excessive oscillation forces having to be applied and without the quality of the welded joint suffering because of this, it is necessary that the friction coefficient between the metal products to be joined lies in a predefined friction coefficient range. According to the invention, this friction coefficient is set by applying, in a controlled way, a scale layer having a thickness d, which is predetermined in accordance with the required friction coefficient, after the cropping but before the welding onto the end face of the leading and/or the lagging metal product.