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Analysis of Spherical Particles Size Distribution – Theoretical Basis

Gurgul D., Burbelko A., Wiktor T.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 1

29--34

EN

The determination of the form of a probability density function (PDF3) of diameters for nodular particles by using a probability density function (PDF2), which form is empirically estimated from cross-sections of these nodules in a metallographic specimen, can be regarded as a special case of Wicksell's corpuscle problem (WCP). The estimation of the PDF3 for the nodular particles provides information about the kinetics of these particles nucleation, and so about the kinetics of their growth. This information is essential for building more accurate mathematical models of the alloy crystallization. In the paper there are presented two derivations of the methods used for the estimation of the PDF3 form. The first method bases on diameters received from a planar cross-section. The second one uses also data from the planar cross-section but not the diameters only chords. Both methods provide practical rules for the analysis of the empirical diameters’ and chord’s size distribution and allow to estimate the mean value of the external surface area of the particles.

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Theory of the Stereological Analysis of Spheroid Size Distribution – Validation of the Equations

Gurgul D., Burbelko A., Wiktor T.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 4

67--72

EN

The paper presents validation tests for method which is used for the evaluation of the statistical distribution parameters for 3D particles’ diameters. The tested method, as source data, uses chord sets which are registered from a random cutting plane placed inside a sample space. In the sample space, there were individually generated three sets containing 3D virtual spheres. Each set had different Cumulative Distribution Function (CDF3) of the sphere diameters, namely: constant radius, normal distribution and bimodal distribution as a superposition of two normal distributions. It has been shown that having only a chord set it is possible, by using the tested method, to calculate the mean value of the outer sphere areas. For the sets of data, a chord method generates quite large errors for around 10% of the smallest nodules in the analysed population. With the increase of the nodule radii, the estimation errors decrease. The tested method may be applied to foundry issues e.g. for the estimation of gas pore sizes in castings or for the estimation of nodule graphite sizes in ductile cast iron.

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Symulacja spiętrzania stopu w komorze zimnokomorowej maszyny ciśnieniowej

Wiktor T., Burbelko A.

Archives of Foundry Engineering

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2015

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Vol. 15, iss. 4 spec.

151--154

PL

Technologia odlewania do form metalowych z wykorzystaniem wysokiego ciśnienia jest jednym ze sposobów wytwarzania odlewów precyzyjnych. Forma metalowa zapewnia precyzję odwzorowania wymiarów gotowego wyrobu, lecz z powodu szczelności materiału, z którego jest wykonana, utrudnia odprowadzanie powietrza z wnęki. Dodatkowo powstawaniu okluzji powietrza sprzyja wysoka prędkość strugi i związany z tym skomplikowany charakter ruchu ciekłego metalu wewnątrz formy. W największym stopniu problem okluzji powietrza występuje w maszynach zimnokomorowych z poziomą komorą wtrysku. W maszynach tego typu dodatkowym źródłem gazów w odlewie może być niewłaściwy przebieg pierwszej fazy pracy maszyny ciśnieniowej. W pracy za pomocą symulacji komputerowych z wykorzystaniem oprogramowania ProCAST (ESI Group®) przeanalizowano zmiany kształtu swobodnej powierzchni stopu EN-AC 44300 AlSi12(Fe) podczas jego spiętrzania w komorze prasowania. Przeanalizowano wpływ prędkości ruchu tłoku, długości komory i stopnia jej wypełnienia na poprawny przebieg tego procesu.

EN

High Pressure Die Casting gives the possibility to produce the cast products with a high precision. Unfortunately, physical properties of the metal molds prevent the air evacuation from the mold cavity. High velocity of the stream and of the free surface movement as well as complicated character of the liquid metal movement prevent the air evacuation and promote the occlusions in the casting. Risk of the air occlusion is the highest in the case of the cold-chamber machines with a horizontal press-chambers. In the HP die casters of this type the addition source of the gas in the casting is the improper evolution of the alloy free surface during the first stage of the cycle (alloy up-rise). In this paper the evolution of the free surface of the EN-AC 44300 AlSi12(Fe) alloy was analyzed by ProCAST software (ESI Group®) in the HP chamber during the first stage of the working cycle. The influence of the piston velocity, shot chamber length and initial level of the alloy in the shot chamber on the behavior of the alloy free surface at this stage was analyzed.