Elliptical Immersion Nozzle for Steel Casting Flow Control
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Solution Overview
Problem
Existing continuous casting methods fail to stabilize the flow of molten steel, leading to surface defects like slivers and blowholes due to alumina inclusions and argon bubbles, which persist in the cast slab despite previous technological advancements.
Innovation Solution
The method involves giving the immersion nozzle an elliptical or oblong horizontal sectional shape with a specific length ratio for its axes, orienting the long axis parallel to the casting mold, and positioning the sliding nozzle perpendicular to it, along with two discharge holes and a sufficient distance from the casting mold, to prevent swirl flow and ensure uniform molten steel distribution, combined with electromagnetic stirring to prevent inclusion entrapment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional circular immersion nozzle is used, then the structure is simple, but swirl flow occurs causing inclusions and bubbles to penetrate deeply into the cast slab
Solution Approach 1:
The patent applies asymmetry by changing the immersion nozzle cross-section from a conventional circular shape to an elliptical shape. This asymmetric geometry prevents the formation of swirl flow by eliminating the symmetric recirculation pattern that occurs in circular nozzles. The elliptical cross-section with specific axis ratios (long axis/short axis between 1.2 and 3.8) disrupts the flow dynamics, preventing alumina inclusions and argon bubbles from being entrained and penetrating deeply into the cast slab, thereby resolving the contradiction between structural simplicity and harmful inclusion entrapment.
2Manufacturing precision
If the immersion nozzle is made rectangular or slit-shaped, then the flow distribution improves, but the discharge flow rate becomes unstable
Solution Approach 1:
The patent applies parameter changes by optimizing the geometric parameters of the elliptical nozzle cross-section, specifically the axis ratio (long axis/short axis between 1.2 and 3.8). This parameter optimization balances flow distribution uniformity with discharge flow rate stability. The specific range of axis ratios ensures that the flow is sufficiently dispersed to prevent localized overheating and inclusion entrapment, while maintaining stable discharge characteristics. This resolves the contradiction between achieving uniform flow distribution and maintaining flow rate stability.
3Length of moving object
If the immersion nozzle is positioned closer to the casting mold, then the penetration depth increases, but inclusions and bubbles are more effectively removed
Solution Approach 1:
The patent applies asymmetry in the nozzle cross-sectional geometry (elliptical rather than circular) to control the flow penetration characteristics. The asymmetric elliptical shape creates a more favorable flow pattern that prevents inclusions and bubbles from being forced deep into the mold while maintaining effective removal. The specific axis ratio range (1.2 to 3.8) optimizes the balance between penetration depth and inclusion removal efficiency, resolving the contradiction between these two opposing requirements.
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 effectively reduces the occurrence of surface and internal defects by preventing alumina and argon bubbles from penetrating deeply into the cast slab, resulting in superior surface and internal quality of the cast product.
Implementation Method 1
giving an inside bore of the immersion nozzle a horizontal sectional shape of an elliptical shape or oblong shape, making a length ratio DL/DS of that long axis DL and short axis DS 1.2 to 3.8, making a direction of that long axis substantially parallel to a long side direction of the casting mold, and making the sliding direction of the sliding nozzle a direction perpendicular to said long axis
Implementation Method 2
it is preferable to cast the molten steel while using an electromagnetic stirring device to impart swirl ability to the steel in the casting mold
Data Source
AI summary
The present invention provides a continuous casting method of steel preventing alumina and other nonmetallic inclusions becoming causes of slivers and argon bubbles becoming causes of blowholes from being entrained and thereby enabling the production of a cast slab superior in surface and internal quality, that is, one giving an inside bore 21 of an immersion nozzle 21 a horizontal sectional shape of an elliptical shape or oblong shape with a length ratio DL/DS of that long axis DL and short axis DS of 1.2 to 3.8, making a direction of that long axis substantially parallel to a long side direction of the casting mold 3, and making the sliding direction of the sliding nozzle 1 a direction perpendicular to said long axis to supply the molten steel in the casting mold 3. Note that a ratio S1/S0 of a sectional area S1 at a smallest sectional area part 23 of the inside bore 21 and a sectional area S0 of a nozzle hole 11 of the sliding nozzle 1 is made 0.5 to 0.95