Thin Slab Casting Mold with Electromagnetic Stirring
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Solution Overview
Problem
In thin slab casting, it is challenging to achieve uniform solidification and prevent longitudinal cracks due to the difficulty in forming a swirl flow near the bath level, which leads to uneven solidification and increased risk of cracks, especially in hypoperitectic steel, where the flow tends to stagnate in narrow gaps between the immersion nozzle and the mold.
Innovation Solution
A continuous casting facility with a mold having copper plate long side walls and an electromagnetic stirring device positioned along the long side wall, where the copper plate thickness, steel piece thickness, and electromagnetic stirring frequency are adjusted to satisfy specific formulae to create a swirl flow, and the short side wall is curved to ensure uniform solidification, preventing cracks by optimizing the electromagnetic stirring and mold geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-speed casting is performed in thin slab casting, then productivity is improved, but uniform solidification becomes difficult to achieve and longitudinal cracks occur
Solution Approach 1:
The electromagnetic stirring device operates periodically to generate alternating magnetic fields that induce swirl flows in the molten steel. This periodic action creates continuous circulation patterns that promote uniform solidification even at high casting speeds, preventing longitudinal cracks while maintaining high productivity
Solution Approach 2:
The patent replaces mechanical stirring methods with electromagnetic stirring. By using electromagnetic fields to generate swirl flows in the molten steel, the system achieves uniform solidification without mechanical contact, enabling high-speed casting while maintaining solidification uniformity and preventing cracks
2Reliability
If electromagnetic stirring device is used to form swirl flow, then solidification uniformity is improved, but device complexity increases
Solution Approach 1:
The electromagnetic stirring device is integrated into the existing mold structure, serving multiple functions: generating swirl flows for uniform solidification, controlling molten steel flow patterns, and preventing inclusion entrapment. This multi-functionality reduces the need for separate devices while achieving reliable solidification
Solution Approach 2:
The patent optimizes parameters such as magnetic field frequency, amplitude, and phase relationships to achieve effective swirl flow generation. By carefully controlling these electromagnetic parameters, the system achieves uniform solidification with a relatively simple device configuration, minimizing added complexity
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 enables uniform solidification across the long side surface, prevents longitudinal cracks, and increases casting speed by maintaining a swirl flow near the bath level, ensuring a rectangular solidified shape and eliminating breakouts due to solidification delays.
Implementation Method 1
an electromagnetic stirring device that is disposed along the long side wall on a back side of the pair of long side walls and provides a swirl flow in a C cross section near a bath level
Implementation Method 2
an electromagnetic stirring device that is disposed along the long side wall on a back side of the pair of long side walls
Implementation Method 3
a mold for casting molten steel that includes a pair of long side walls and a pair of short side walls that are each formed from a copper plate
Data Source
AI summary
A continuous casting facility used for thin slab casting has a mold for casting molten steel, an immersion nozzle that supplies the molten steel into the mold, and an electromagnetic stirring device capable of providing a swirl flow at a molten steel surface in the mold, and a thickness DCu (mm) of a copper plate of a long side wall, a thickness T (mm) of a steel piece, a frequency f (Hz) of the electromagnetic stirring device, electric conductivity σ (S/m) of the molten steel, and electric conductivity σCu (S/m) of the copper plate of the long side wall are adjusted to satisfy the following formulae (1)-a and (1)-b:DCu<√(2/σCuωμ) (1)-a√(1/2σωμ)<T (1)-b,where ω=2πf: angular velocity (rad/sec), and μ=4π×10−7: magnetic permeability in vacuum (N/A2).