A Criterion for Air-Gap Formation in Vertical Continuous Casting: The Effect of Superheat

2014 ◽  
pp. 185-190
Author(s):  
Michael Vynnycky
Keyword(s):  
Continuous Casting ◽  
Air Gap ◽  
Gap Formation

Mould-taper asymptotics and air gap formation in continuous casting

2015 ◽  
Vol 268 ◽  
pp. 1122-1139 ◽  
Author(s):  
B.J. Florio ◽  
M. Vynnycky ◽  
S.L. Mitchell ◽  
S.B.G. O’Brien
Keyword(s):  
Continuous Casting ◽  
Air Gap ◽  
Gap Formation

3D Thermo-Mechanical Modelling of Wheel and Belt Continuous Casting

2011 ◽  
Vol 693 ◽  
pp. 235-244 ◽  
Author(s):  
John F. Grandfield ◽  
Sébastien Dablement ◽  
Hallvard Gustav Fjær ◽  
Dag Mortensen ◽  
Michael Lee ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Continuous Casting ◽  
Three Dimensional ◽  
Casting Process ◽  
Liquid Pool ◽  
Air Gap ◽  
Temperature Measurements ◽  
Heat Extraction ◽  
Gap Formation ◽  
Solidification Defects

Wire rod is produced by hot-rolling a bar of metal coming from a wheel/belt continuous casting process. This kind of process, e.g. Properzi, is an elaborate process in which the molten metal is poured in a cooled rotating mould formed by the groove of a wheel and closed by a belt. In order to better understand the heat transfer phenomenon and solidified bar characteristics, depending on process parameters a three dimensional thermo-mechanical model has been developed. The model, based on the finite-element method, calculates the heat transfer coefficient of the air gap at the metal-mould interface as a function of the size of the gap determined by the bar contraction and wheel and belt thermal deformations. The air gap formation due to metal shrinkage and mould deformation is the main factor which determines the heat extraction. Wheel temperature measurements with thermocouple and belt temperature measurements with an infrared system were carried out to verify model results. Attempts were also made to measure a liquid pool profile using doping with copper rich alloy. The model shows the effect of the casting temperature and the rotation speed on the air gap formation and resulting temperature and stress fields. The model can be applied to issues such as maximising wheel and belt life and minimising solidification defects.

Conjugate Heat Transfer and Effects of Interfacial Heat Flux During the Solidification Process of Continuous Castings

2003 ◽  
Vol 125 (2) ◽  
pp. 339-348 ◽  
Author(s):  
M. Ruhul Amin ◽  
Nikhil L. Gawas
Keyword(s):  
Heat Transfer ◽  
Continuous Casting ◽  
Cooling Rate ◽  
Solidification Process ◽  
Air Gap ◽  
Gap Formation ◽  
Continuous Casting Mold ◽  
Withdrawal Velocity ◽  
Multiphase Fluid Flow ◽  
Multiphase Fluid

Multiphase fluid flow involving solidification is common in many industrial processes such as extrusion, continuous casting, drawing, etc. The present study concentrates on the study of air gap formation due to metal shrinkage on the interfacial heat transfer of a continuous casting mold. Enthalpy method was employed to model the solidification of continuously moving metal. The effect of basic process parameters mainly superheat, withdrawal velocity, mold cooling rate and the post mold cooling rate on the heat transfer was studied. The results of cases run with air gap formation were also compared with those without air gap formation to understand the phenomenon comprehensively. The current study shows that there exists a limiting value of Pe above which the effect of air gap formation on the overall heat transfer is negligible.

An asymptotic model for the formation and evolution of air gaps in vertical continuous casting

2009 ◽  
Vol 465 (2105) ◽  
pp. 1617-1644 ◽  
Author(s):  
M. Vynnycky
Keyword(s):  
Continuous Casting ◽  
Moving Boundary ◽  
Three Dimensional ◽  
Air Gap ◽  
Parabolic Partial Differential Equation ◽  
Asymptotic Model ◽  
Gap Formation ◽  
Type Boundary ◽  
Almost All ◽  
Type Boundary Condition

The formation of an air gap at the mould–metal interface in vertical continuous casting has long been known to have a detrimental effect on the efficiency of the process, and has therefore attracted attempts at mathematical modelling. While almost all current efforts consist of complex three-dimensional numerical simulations of the phenomenon, this paper considers instead an asymptotic model that captures the essential characteristics. The model is thermomechanical and is derived for a geometry, where the generalized plane strain approximation is appropriate. Although two-way coupling between the thermal and mechanical problems is accounted for, it is found that the problems decouple at leading order anyway, and that the thickness of the air gap does not depend on the constitutive relation used for describing the inelastic strains. Furthermore, a criterion for the onset of air-gap formation is derived in terms of the process operating parameters. Mathematically, we obtain a moving boundary problem for a parabolic partial differential equation with a degenerate initial condition and a non-standard Neumann-type boundary condition. Sample computations are performed using parameters for the continuous casting of the copper, and the results, qualitative trends and possible extensions are discussed.

scholarly journals A validated asymptotic thermomechanical model for air-gap formation in tapered moulds in the continuous casting of steel

2021 ◽  
Vol 86 (2) ◽  
pp. 129-157
Author(s):  
K M Devine ◽  
M Vynnycky ◽  
S L Mitchell ◽  
S B G O’Brien
Keyword(s):  
Continuous Casting ◽  
Moving Boundary ◽  
Cooling Water ◽  
Element Model ◽  
Air Gap ◽  
Gap Formation ◽  
Complex Interplay ◽  
Thermomechanical Model ◽  
Model Equations ◽  
Air Interfaces

Abstract A recent asymptotics-based thermomechanical model is adapted and applied to the mould region in the continuous casting of round steel billets, with a view to describing the complex interplay between air-gap formation, mould taper, cooling channel width and cooling water velocity. Although the situation is steady state, the analysis leads to what is mathematically a dual moving-boundary problem for the solid–melt and solid–air interfaces, where the distance from the top of the mould region is the time-like variable in the problem. Moreover, the two interfaces are initiated at different locations. In addition, the thermal and mechanical problems are found to decouple and it is possible to solve the first ahead of the second. The model equations are solved numerically using a finite-difference method, and the approach is subsequently successfully validated against a previous finite-element model and experimental data from temperature measurements taken within the mould.

scholarly journals Heat Transfer Coefficient Determination in a Gravity Die Casting Process with Local Air Gap Formation and Contact Pressure Using Experimental Evaluation and Numerical Simulation

2021 ◽  
Author(s):  
T. Vossel ◽  
N. Wolff ◽  
B. Pustal ◽  
A. Bührig-Polaczek ◽  
M. Ahmadein
Keyword(s):  
Heat Transfer ◽  
Contact Pressure ◽  
Local Heat Transfer ◽  
Casting Process ◽  
Local Heat ◽  
Air Gap ◽  
Gap Formation ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Die Casting Process

AbstractAnticipating the processes and parameters involved for accomplishing a sound metal casting requires an in-depth understanding of the underlying behaviors characterizing a liquid melt solidifying inside its mold. Heat balance represents a major factor in describing the thermal conditions in a casting process and one of its main influences is the heat transfer between the casting and its surroundings. Local heat transfer coefficients describe how well heat can be transferred from one body or material to another. This paper will discuss the estimation of these coefficients in a gravity die casting process with local air gap formation and heat shrinkage induced contact pressure. Both an experimental evaluation and a numerical modeling for a solidification simulation will be performed as two means of investigating the local heat transfer coefficients and their local differences for regions with air gap formation or contact pressure when casting A356 (AlSi7Mg0.3).

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