Electromagnetic Stirring Device for Continuous Casting
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Solution Overview
Problem
Existing electromagnetic stirring devices face challenges in generating a sufficient swirling flow around a vertical axis in molten metal during continuous casting, particularly when the mold dimensions are close in length, leading to issues like impurity entrapment, non-uniform temperature, and potential cracks in the bloom.
Innovation Solution
An electromagnetic stirring device with an iron core enclosing the mold and two teeth arranged side by side in the circumferential direction, each with a coil wound around it, applies a rotating magnetic field by alternating current with a phase shift of 90°, generating a swirling flow around the vertical axis while minimizing vertical flow components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an iron core with a coil is arranged only at the side of the outer side surface on the long side of the mold, then the device complexity is reduced, but the swirling flow generation capability is insufficient
Solution Approach 1:
The iron core is segmented into multiple portions (first iron core portion and second iron core portion) arranged at different sides of the mold. Each portion has coils wound around it, creating distributed magnetic field sources that collectively generate the required swirling flow pattern throughout the mold cavity.
Solution Approach 2:
Multiple iron core portions and their associated coils are combined to form an integrated electromagnetic stirring system. The magnetic fields from each segment merge to create the rotating magnetic field necessary for effective swirling flow generation in the molten metal.
2Manufacturing precision
If magnetic pole portions are arranged for each outer side surface including short sides, then the swirling flow generation is improved, but vertical flow occurs due to eddy currents in the mold plate
Solution Approach 1:
The iron core portions are strategically positioned to face specific outer side surfaces of the mold. The magnetic pole portions create localized magnetic fields that are optimized for generating horizontal swirling flow while minimizing penetration into the mold plate that would induce harmful eddy currents and vertical flow.
Solution Approach 2:
The design acknowledges that some magnetic flux will penetrate the mold plate, but configures the system so that the primary effect occurs in the molten metal where it generates beneficial swirling flow. The eddy currents in the mold plate, while potentially harmful, are minimized through proper positioning and orientation of the magnetic pole portions.
3Shape
If the difference between long side and short side of the mold is small, then the mold geometry is more compact, but it becomes difficult to generate sufficient swirling flow around the vertical axis
Solution Approach 1:
Even though the mold may have similar dimensions on all sides, the iron core portions and magnetic pole portions are arranged asymmetrically relative to the mold geometry. This asymmetric arrangement creates a rotating magnetic field pattern that effectively generates swirling flow around the vertical axis, overcoming the limitations of compact mold geometries where long and short sides are similar in length.
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 configuration effectively generates a swirling flow around the vertical axis, suppresses vertical flow in the molten metal, and improves the quality of the bloom by reducing impurity entrapment and ensuring uniform temperature, eliminating the need for winding the coil around the iron core in a specific direction during manufacturing.
Implementation Method 1
A moving magnetic field may be generated in the mold by application of an alternating current to the coil of the electromagnetic stirring device
Implementation Method 2
applying an electromagnetic force referred to as a Lorentz force to the molten metal in the mold to generate a flow pattern which swirls in a horizontal plane
Implementation Method 3
A moving magnetic field may be generated in the mold by application of an alternating current to the coil of the electromagnetic stirring device
Data Source
AI summary
This electromagnetic stirring device configured to apply an electromagnetic force which generates a swirling flow around a vertical axis to molten metal in a mold by generating a rotating magnetic field in the mold, which is a quadrangular tubular mold for continuous casting, the electromagnetic stirring device provided with an iron core enclosing the mold at a side of the mold and including two teeth arranged side by side in a circumferential direction of the mold so as to face an outer side surface for each of outer side surfaces of the mold, coils wound around the respective teeth of the iron core, and a power supply device which applies an alternating current to each of the coils with a phase shift by 90° in arrangement order of the coils so as to generate the rotating magnetic field.