Immersion Nozzle Neckless Design for Crack Prevention
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Solution Overview
Problem
Immersion nozzles in continuous steel casting face crack formation due to thermal and mechanical stresses at the neck region, leading to durability issues and steel quality degradation.
Innovation Solution
The immersion nozzle is designed without a neck region, featuring a right circular tubular shape with a flange and metal casing configuration, where the joint strength between the nozzle body and flange is less than their bending strength, allowing for stress distribution and preventing crack formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an immersion nozzle has a neck region (cross-sectional area increases upwardly), then it can be supported by a supporting device, but crack formation occurs due to thermal and mechanical stress concentration
Solution Approach 1:
The immersion nozzle is divided into separate components: a nozzle body and a flange, which are joined together. This segmentation allows the flange to provide support contact area without creating stress concentration in the nozzle body, as the flange acts as a separate structural element that distributes mechanical loads away from the thermal stress-prone neck region.
Solution Approach 2:
A joining structure (such as a joining portion or adhesive layer) is introduced between the nozzle body and flange. This intermediary element allows the flange to provide mechanical support while preventing direct stress transmission to the nozzle body, thereby eliminating the neck region stress concentration problem while maintaining supportability.
2Strength
If the nozzle body and flange are joined strongly, then structural integrity is improved, but stress concentration at the joint increases crack risk
Solution Approach 1:
The joining strength parameter is specifically controlled to be lower than the bending strength of the nozzle body and flange. This parameter change ensures that the joint can flexibly accommodate thermal expansion and mechanical stresses without creating rigid stress concentration points, thereby preventing crack formation while maintaining adequate structural integrity.
3Productivity
If a neck region is present to allow flange support, then the nozzle can be replaced using immersion nozzle replacement apparatus, but durability is reduced due to crack formation
Solution Approach 1:
By segmenting the nozzle into a replaceable nozzle body and a support flange, the design enables efficient replacement of the nozzle body while the flange remains as a durable support component. The joining structure allows for easy detachment and reattachment, facilitating rapid replacement without compromising durability.
Solution Approach 2:
The nozzle body is designed as a replaceable component that can be efficiently replaced when worn, while the flange serves as a reusable support structure. This approach allows for cost-effective maintenance by replacing only the consumable nozzle body rather than the entire assembly.
Data Source
AI summary
An immersion nozzle for use with an immersion nozzle replacement apparatus, capable of preventing crack formation due to the presence of a neck region. The immersion nozzle includes a nozzle body, a flange, and a metal casing. The nozzle body is formed such that a region of an outer peripheral surface thereof located above a point of power of an upward supporting force from a supporting device extends vertically up to an upper edge of the nozzle body without any dimensional change with respect to an central axis of an inner bore of the nozzle body. The outer peripheral surface region is not joined to the metal casing.