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1
Content available Numerical modeling of the solidification process with consideration of shrinkage cavities formation and the influence of solid phase content on the feeding of the casting
Węgrzyn-Skrzypczak Ewa, Skrzypczak Tomasz
Journal of Applied Mathematics and Computational Mechanics
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2023
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Vol. 22, nr 2
75--86
EN
The paper focuses on the numerical modeling of the three-dimensional solidification process of steel using the finite element method (FEM). The model includes and discusses the formation of shrinkage cavities and the influence of the solid phase content on the feeding of the casting through the riser. The analysis assumed a critical value of the solid phase content, at which the transport of liquid phase from the riser to the casting is interrupted. The results of numerical simulation are presented to investigate the influence of this factor on the final quality of the casting. The model neglects the fluid motion in the liquid and solid-liquid regions and replaces the influence of the mold with appropriate boundary conditions.
2
Content available The Process of Vacuum Formation in the Shrinkage Cavity at Castings Crystallization
Khrychikov V., Semenov O., Meniailo H., Aftandiliants Y., Gnyloskurenko S.
Archives of Foundry Engineering
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2022
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Vol. 22, iss. 4
79--84
EN
The formation process of one of the most common casting defects, a shrinkage depression concerned to shrinkage cavity, was studied. The methodology, device and the experimental set up were developed to study the shrinkage cavity growth. The kinetics of vacuum formation in the cavity of the spherical casting of Al-Si-Mg alloy at its solidification in the sand-and-clay form was investigated. The data were analysed taking in mind the temperature variation in the centre of crystallizing casting. The causes of the shrinkage depression in castings were clarified. It was determined that atmospheric pressure leads to the retraction and curvature of metal layer on the surface of the casting with lower strength below which the shrinkage cavity is formed. To avoid such defects it was recommended to use the external or internal chills, feeders and other known technological methods. Deep shrinkage cavities inside the castings could be removed with an air flow through a thin tubular needle of austenitic steels for medical injections.
3
Content available Numerical Model of Solidification Including Formation of Multiple Shrinkage Cavities
Skrzypczak T., Sowa L., Węgrzyn-Skrzypczak E.
Archives of Foundry Engineering
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2020
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Vol. 20, iss. 1
37--42
EN
Presented paper shows the mathematical and numerical approaches for modelling of binary alloy solidification solved by the Finite Element Method (FEM). The phenomenon of shrinkage cavities formation process is included in the numerical model. Multiple macroscopic cavities can be modelled within the single casting volume. Solid, liquid and gaseous phases with different material properties are taken into account during solidification process. Mathematical model uses the differential equation of heat diffusion. Modification of specific heat is used to describe the heat releasing during liquid-solid phase change. Numerical procedure of shrinkage cavities evolution is based on the recognition of non-connected liquid volumes and local shrinkage computation in the each of them. The recognition is done by the selection of sets of interconnected nodes containing liquid phase in the finite element mesh. Original computer program was developed to perform calculation process. Obtained results of temperature and shrinkage cavities distributions are presented and discussed in details.
4
Content available The Influence of Using Different Types of Risers or Chills on Shrinkage Production for Different Wall Thickness for Material EN-GJS-400-18LT
Vaskova I., Conev M., Hrubovcakova M.
Archives of Foundry Engineering
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2017
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Vol. 17, iss. 2
131--136
EN
In modern times there are increasing requirements for products quality in every part of manufacturing industry and in foundry industry it is not different. That is why a lot of foundries are researching, how to effectively produce castings with high quality. This article is dealing with search of the influence of using different types of risers or chills on shrinkage cavity production in ductile iron castings. Differently shaped risers were designed using the Wlodawer´s modulus method and test castings were poured with and without combination of chills. Efficiency of used risers and chills was established by the area of created shrinkage cavity using the ultrasound nondestructive method. There are introduced the production process of test castings and results of ultrasound nondestructive reflective method. The object of this work is to determine an optimal type of riser or chill for given test casting in order to not use overrated risers and thus increase the cost effectiveness of the ductile iron castings production.
5
Content available Mathematical model of solidification of the axisymmetric casting while taking into account its shrinkage
Sowa L.
Journal of Applied Mathematics and Computational Mechanics
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2014
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Vol. 13, nr 4
123--130
EN
In this paper, the mathematical and numerical model of the solidification of a cylindrical shaped casting, while taking into account the process of the mould cavity filling with molten metal, has been proposed. The feeding of the casting by a riser head during solidification and the formation of shrinkage cavity has also been taken into consideration. The shape and depth of the shrinkage cavity distribution was estimated. One aim of the paper is to obtain a casting without shrinkage defects. Velocity fields were obtained by solving the Navier-Stokes equations and the continuity equation, while the thermal fields were obtained by solving the conduction equation containing the convection term. The changes in the thermophysical parameters, with respect to temperature, were taken into account. The problem was solved by the finite element method.
6
Content available remote Simulation of shrinkage cavity formation during solidification of binary alloy
Skrzypczak T., Węgrzyn-Skrzypczak E.
Archives of Foundry Engineering
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2010
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Vol. 10, iss. 1
147-152
EN
Presented paper is focused on numerical modeling of binary alloy solidification process with connection to shrinkage cavity formation phenomenon. Appropriate matching of cooling parameters during solidification process of the cast with raiser is essential to obtain suitable properties of the manufactured part. Localization, structure and depth of the shrinkage cavity is connected to these parameters. The raiser is removed after process, so defect localization in the top part of the manufactured element is of great importance. Mathematical model of solidification process is presented in the paper. The main focus is put on the algorithm of shrinkage cavity creation process. On the basis of mathematical model the numerical approach using finite element method is proposed. On the base of mathematical and numerical model computer program is made. It is able to perform simulation of the shrinkage cavity formation in 2D region. Shape and localization of shrinkage cavity obtained from simulation is compared to defect which was created during experiment.
7
Content available remote Analysis of three-dimensional binary alloy solidification with shrinkage cavity formation
Skrzypczak T., Węgrzyn-Skrzypczak E.
Archives of Foundry Engineering
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2010
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Vol. 10, iss. 4
199--204
EN
The paper focuses on modeling of binary alloy solidification process with using Finite Element Method (FEM). The process is characterized by liquidus and solidus temperatures which are constant because solutal segregation is neglected. Analysed region is threedimensional and consists of casting and riser. Mathematical and numerical models of solidification process are presented in the paper. The main focus is put on the algorithm of shrinkage cavity creation process. On the base of mathematical and numerical model computer program has been made. It is capable to simulate shrinkage cavity formation. Two examples show the results of different calculations performed by the program. The first example shows shrinkage cavity created during fast cooling of the top part of the riser while the second one was performed by significantly slower cooling. The shape and localization of shrinkage cavity obtained from simulation is compared to defect which was created during experiment.
8
Content available remote Numeryczna symulacja procesu krzepnięcia nadlewu w formie z modułem izolacyjnym
Gradowski A.
Archiwum Odlewnictwa
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2006
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R. 6, nr 21/2
185-192
PL
W artykule przedstawiono model symulacji liczbowej procesu zasilania metalem odlewu płyty staliwnej, stosując w tym celu wybrane rodzaje nadlewów. Zastosowanie formy z wnęką wyłożoną materiałem izolacyjnym sprawia, że na bocznej powierzchni nadlewu zachodzi zmniejszona wymiana ciepła. Celem badań zaprezentowanych w tym artykule było przeprowadzenie analizy liczbowej procesu krzepnięcia ciekłego metalu oraz przemieszczenia i rozkładu obszaru występowania jamy skurczowej w nadlewie o kształcie walca. W oparciu o model matematyczny i fizyczny wyżej wymienionego procesu opracowano program symulacyjny, który ma za zadanie wizualne, graficzne i cyfrowe przedstawienie charakterystycznych parametrów procesu. Opracowany program umożliwia optymalizację skuteczności procesu zasilania.
EN
The paper presents a model of numerical simulation of feeding process of caststeel plate by risers of the selected types. Application mould with insulating cavity is followed by a reduction of the heat exchanged on the lateral surface of the riser. The aim of this study is a numerical analysis of liquid metal solidification and displacement and distribution of area of the shrinkage cavity in the cylindrical riser. Based on a mathematical and physical model of the aforementioned processes there was developed simulation software for a visual, graphical and digital representation of the characteristic parameters of these processes. The software developed enables a optimization of feeding effectiveness process.
9
Content available remote Symulacja numeryczna jamy skurczowej w krzepnącym odlewie staliwnym
Sowa L.
Archiwum Odlewnictwa
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2002
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R. 2, nr 4
245--250
PL
W pracy sformułowano model matematyczny i numeryczny procesu krzepnięcia odlewu o kształcie cylindrycznym z uwzględnieniem procesu wypełniania wnęki formy ciekłym metalem, zasilania odlewu przez nadlew podczas jego krzepnięcia oraz powstawania i zalegania jamy skurczowej. Oceniano kształt i głębokość zalegania jamy skurczowej w zależności od własności termofizycznych nadlewu. Dążono do otrzymania odlewu bez wad pochodzenia skurczowego. Uwzględniono wzajemną zależność zjawisk cieplnych i dynamicznych. Pola prędkości otrzymano z rozwiązania równań Naviera-Stokesa i równania ciągłości przepływu, natomiast pola temperatury z rozwiązania równania przewodnictwa ciepła z członem konwekcyjnym. Założono zmianę parametrów termofizycznych w funkcji temperatury. Postawione zadanie rozwiązano metodą elementów skończonych.
EN
In the paper, mathematical and numerical models of the solidification of a cylindrical shaped casting, with taking into account the process of the mould cavity filling with molten metal, has been proposed. The feeding of the casting by a riser head during solidification and shrinkage cavity distribution has also been taken into consideration. The shape and deep of shrinkage cavity distribution depending on thermophysical properties of a riser head were estimated. One aims in the paper to obtain a casting without shrinkage defect. Velocity fields were obtained by solving the Navier-Stokes equations and the continuity equation, while the thermal fields were obtained by solving the conduction equation containing the convection term. The changes in the thermophysical parameters, with respect to temperature, were taken into account. The problem was solved by the finite element method.
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