Tilted Pressure Rollers Mash Seam Welding Step Gradient
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Solution Overview
Problem
Conventional mash seam welding methods result in a joint portion thickness that is 120% to 160% of the base material thickness, leading to a steep step and stress concentration, which limits the application range, increases the risk of fracture, and reduces productivity and yield, especially in cold rolling and tailored blanks processes.
Innovation Solution
The method involves tilting the axes of upper and lower pressure rollers in a horizontal plane perpendicular to the joint line, applying a shearing force to reduce the thickness of the joint portion, thereby smoothing the step and reducing the step gradient, and adjusting tilt angles based on the step amount to ensure appropriate shear deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional mash seam welding is used to join metal plates, then the joint portion is formed by heating and rolling, but the joint portion thickness increases to 120%-160% of base material thickness, creating a steep step and stress concentration
Solution Approach 1:
The invention applies preliminary rolling action before welding by positioning pressure rollers upstream of the electrode wheels. This preliminary rolling pre-compresses and thins the overlapping joint portion before the welding process, preventing excessive thickness buildup and reducing the step gradient at the joint portion while maintaining joint strength
Solution Approach 2:
The invention introduces a new dimensional approach by tilting the pressure rollers at a specific angle (10-30 degrees) relative to the welding direction. This angular orientation creates a shearing action that effectively reduces joint portion thickness in a direction complementary to the conventional rolling action, thereby reducing the step gradient without compromising joint strength
2Shape
If the joint portion thickness is reduced by conventional rolling methods, then the step gradient is reduced, but the rolling action is restrained by the base material and cannot achieve base material thickness
Solution Approach 1:
The invention changes the operational parameters by introducing tilted pressure rollers with a specific angle (10-30 degrees) and positioning them upstream of the welding zone. This parameter change enables the rolling action to overcome the restraining effect of the base material by creating a shearing component that facilitates material flow, allowing the joint portion to be reduced to approximately base material thickness while maintaining joint strength through the combined rolling and welding process
3Productivity
If a steep step is formed at the joint portion, then the welding process is simpler and faster, but stress concentration increases and application range is limited
Solution Approach 1:
The invention performs preliminary rolling before welding to pre-thin the joint portion, which reduces the material that needs to be melted and re-solidified during welding. This maintains welding speed and productivity while significantly reducing the step gradient and stress concentration at the joint portion, thereby expanding the application range to include more critical structural applications
4Shape
If pressure rollers are installed adjacently to electrode wheels for rolling before and after welding, then joint portion thickness is reduced, but the process complexity increases
Solution Approach 1:
The invention extracts and separates the rolling function from the welding function by positioning pressure rollers upstream of the electrode wheels. This separation allows the rolling process to be independently optimized and controlled, reducing joint portion thickness before welding without adding excessive complexity, as the rolling and welding zones are spatially distinct and can be independently managed
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 enhances joint strength, prevents work roll scratches, improves productivity and yield, and allows mash seam welding to be applied to processes previously unsuitable, such as cold rolling and tailored blanks, by reducing stress concentration and maintaining high-quality joint formation.
Implementation Method 1
respective axes of the pair of pressure rollers are tilted in a horizontal plane with respect to a straight line perpendicular to a joining line of the joint portion... applying a shearing force to reduce the thickness of the joint portion
Implementation Method 2
The joint portion softened by being heated to high temperature is rolled by the electrode wheels to reduce the thickness of the joint portion... the joint portion cannot be rolled to a level corresponding to the base material thickness
Implementation Method 3
the overlapping portions are pressed by a pair of electrode wheels and continuously welded together by applying a welding current thereto... The overlapping portions are pressed by the pair of electrode wheels and continuously welded together by applying a welding current thereto
Data Source
AI summary
A pair of upper and lower pressure rollers 3, 4 is disposed so that their axes 15, 16 are tilted in a horizontal plane in respective directions opposite to each other with respect to a straight line perpendicular to a welding line of a joint portion J. The pressure rollers 3, 4 are positively driven by corresponding electric motors 63, 64 to thereby roll the joint portion. Thus, steps defined at the joint portion can be smoothed and a step gradient can be reduced to ensure a high degree of joint strength. Thus, it is possible to prevent a step portion from being interfolded into the base material of the meal plates 5, 6.