In this study, the analysis of the influence of the pouring temperature on manufacture process of castings by the Lost Foam method was introduced. In particular, numerical simulation results of effect of silumin and grey cast iron pouring temperature on pouring rate and gas gap pressure were analyzed. For simulating investigations of the Lost Foam process introduced mathematical model of the process was used. For calculations, the author's own algorithm was applied. The investigations have proved that with increasing pouring temperature the pouring rate increases, while pressure in the gas gap are decreasing. The author's own investigations showed a more significant effect of the silumin pouring temperature than grey cast iron pouring temperature on the lost foam process.
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Technology of polystyrene pre-expansion process by use of test stand equipped with batch pre-expander was displayed. Additionally the test stand is fit out with fluidized bed dryer and silo for aging pre-expanded polystyrene. Studies of pre-expansion process, to determine the effect of the expansion pressure and expansion time on foamed polystyrene granule bulk density , were carried out. Also carried out researches determining influence of drying process and aging time on foamed polystyrene density. Analysis of test results confirmed that with increasing of expansion pressure up to 1,4 bar the bulk density of polystyrene decreases. Similarly, it was found that with increasing expansion time bulk density decreases.
PL
W pracy przedstawiono technologie wstępnego spieniania polistyrenu na stanowisku badawczym wyposażonym w spieniarkę cykliczną. Stanowisko badawcze wyposażone jest w spieniarkę do pracy cyklicznej, suszarkę fluidyzacyjną oraz silos do sezonowania wstępnie spienionego polistyrenu. Przeprowadzono badania procesu wstępnego spieniania mające na celu określenie wpływu ciśnienia spieniania, czasu spieniania, na gęstość nasypowa granulek styropianu. Przeprowadzono również badania mające określić wpływ procesu suszenia i czasu sezonowania na gęstość spienionego styropianu. Analiza wyników badań potwierdziła, że wraz ze wzrostem ciśnienia wstępnego spieniania do ciśnienia 1,4 bar gęstość nasypowa styropianu maleje. Podobnie stwierdzono, że wraz ze wzrostem czasu spieniania gęstość nasypowa maleje.
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In the study, a pre-expansion station, designed by authors, was presented. It consists of a batch pre-expander with a 90 liters capacity foaming chamber, equipped with fluidized-solid dryer of pre-expanded beads and a pneumatic transport system of granules to the silo. Steam is delivered to the pre-expander from the electric vapor generator type LW 40.1. In the study, work principle of the pre-expansion station and pre-expansion tests carried out on this position were presented.
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Problems of environmental protection are nowadays one of the top priorities in a policy programme adopted by the European Community. Reducing the negative impact of the domestic foundry industry on environment should result from complex and long-lasting activities, targeted not only at modernisation of the dust collecting units, but also at searches and implementation of alternative, innovative and more pro-ecology oriented means and techniques of casting manufacture. Reducing to minimum the level of emissions escaping to the environment should be considered at all stages of the casting manufacturing process. In this study, the discussion was restricted to the process of the manufacture of moulds and cores for piece production of the heavy castings. The environmental impact of the technology of making moulds and cores in sands with chemical binders, used most often in piece production of large castings poured from iron alloys, was highlighted. As an alternative technology of mould preparation for the piece production of castings, the ecological and economic aspects of the full mould process were presented.
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In this study, the analysis of the influence of the pressure in mould on manufacture process of castings by the Lost Foam method was introduced. In particular, numerical simulation results of effect of pressure in mould on pouring rate, gas gap pressure and gas gap size were analyzed. For simulating investigations of the Lost Foam process introduced mathematical model of the process was used. In this model in detail was described and derived equation relating to the changes of the gas pressure in the gas gap. The mathematical description uses the equation of gas state and the equation of Darcy’s rate of filtration. Presented studies indicated, that with decrease of pressure in mould the pouring rate increased and the gas pressure in gas gap and gas gap size decreased. For pressures in mould from the range of 20÷100 kPa, pouring rates achieved values from 30÷3 cm/s respectively.
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The analysis of the influence of the thickness of refractory coating on the production process of casts in the Lost Foam process was introduced in the work. It was conducted in the peculiarity the analysis simulating investigations the influence the coating thickness on the pouring rate, pressure in the gas gap and gas gap size. For simulation tests of the Lost Foam process, a mathematical model presented in this study was used. For calculations, the author's own algorithm was applied. Investigations have proved that with increasing thickness of coating the pouring rate decreases, while pressure in the gas gap and the size of the gap are increasing. The author's own investigations have proved a very significant effect of the coating thickness on the Lost Foam process, and specially on the mould pouring rate.
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The article analyses the effect of refractory coating permeability on the process of casting manufacture by the Lost Foam technique. The analysis was focussed on simulation tests examining the effect of coating permeability on the mould cavity filling rate, pressure in gas gap, and the size of this gap. In simulation tests of the Lost Foam Process, a mathematical model of the process presented in this study and the author's own computation algorithm were used. The computations have proved that with increasing permeability of the protective coating, the pouring rate increases, too, while pressure of gas in the gas gap and the size of the gap are decreasing. The increasing pouring rate ensures correct making of castings, even if their shape is very intricate and the wall cross-sections are very small. Smaller size of the gas gap and lower gas pressure in the gap reduce the risk of mould damage. The author's own investigations confirmed the importance of the refractory coating permeability and its effect on the casting process, mould pouring rate - in particular.
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In the study, a model and some fundamental relationships describing changes of gas pressure in the gas gap during manufacture of castings by the Lost Foam process were described. The mathematical description uses the equation of gas state and the equation of Darcy's rate of filtration. The equations describing changes of gas pressure in the gas gap and the kinetics of melting of a foamed polystyrene pattern as well as the dynamics of the process of mould filling with molten alloy were used in analysis of the effect of selected technological parameters on changes of gas pressure in the gas gap. The effect of foamed polystyrene pattern density and permeability, and of the protective coating thickness on changes of pressure in the gas gap were discussed.
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The study examines the effect of the foamed polystyrene pattern density on the process of making castings by the lost foam technique with emphasis put on the analysis of simulation tests. The simulation regarded the effect that pattern density is said to have on the mould cavity filling rate, pressure in the gas gap, and size of this gap. For simulation tests of the full mould process, a mathematical model presented in this study was used. For calculations, the author's own algorithm was applied. The investigations have proved that with decreasing pattern density the pouring rate increases, while pressure in the gas gap and the size of the gap are decreasing. The increasing pouring rate ensures correct making of castings, even if their shapes are very intricate and the wall cross-sections are very small. Smaller size of the gas gap and lower pressure of gases in this gap reduce the risk of mould damage. The author�fs own investigations have proved a very significant effect of the density of foamed polystyrene pattern on the casting process, and specially on the mould pouring rate. The best pouring rate is ensured by patterns of the density comprised in a range of p2 =18-25 kg/m3.
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