Чтение и адекватный перевод оригинального текста по специальности аспиранта (соискателя). Significance of the casting process parameters

МИНИСТЕРСТВО ОБРАЗОВАНИЯ РЕСПУБЛИКИ БЕЛАРУСЬ

ГОМЕЛЬСКИЙ ПОЛИТЕХНИЧЕСКИЙ ИНСТИТУТ им.П.О.СУХОГО

Кафедра белорусского и иностранного языков.

Приложение к билету для экзамена по сдаче кандидатского минимума.

английский язык

Вопрос 1 . Чтение и адекватный перевод оригинального текста по специальности аспиранта (соискателя).

Шифр: 05.16.04.

Significance of the casting process parameters.

It is evident, that not only the casting/mould system geometry is decisive about stresses and contraction or removal forces at a given temperature.This is due to both the time-dependency of mechanical behaviour of cast metals at high homologous temperatures and the dependency of mechanical strains on thermal conditions of the process.

Using the computer program presented above, over 30 numerical simulations were made in order to Study the influence of various parameters of the process on the magnitude of the contraction stresses. A thin-walled, tube-shaped aluminium alloy casting made in a gravity die was assumed. The major conclusions resulting from the simulations are the following:

• Alterations of geometrical parameters influencing the heat transfer in the casting/mould/environment system (i.e. weights and surfaces of the casting and the mould) have a significant influence on the contraction forces only at temperatures of the casting lower then the maximum mould temperature in the cycle, i.e. beyond the practical range of removal temperatures.

• The most weighty parameter was the initial temperature of the mould (assumed here to be uniform in the whole body, including the parts surrounded by the cast metal). It seems to be important to evaluate the increase of the removal forces in case the mould is not preheated enough.

• A proper combination of two or more changes can give a desirable reduction of the contraction forces without sacrificing the other parameters. The most important seems to be the simultaneous increase of the mould temperature before pouring .and reduction of the heat resistance of the cavity rating (application of carbon-based materials in thin layers). A considerable reduction of the contraction forces can be expected in the whole practical range of removal temperatures while the rate of cooling, particularly during mould filling. can be kept unchanged.

There is no general rule for improvements of casting in metallic moulds, resulting from the presented material. leading to an extension of the capabilities of the processes. However, it should be noticed that the proposed methods of calculation of the mechanical loadings acting on castings and mould elements as well as the procedures of the strength analysis offer some new advantages. The most important of them seem to be the following:

• Knowledge of the loadings values acting on the mould^,s elements facilitates more economical selection and design of the driving elements or the whole casting machines.

• Knowledge of the loadings to which the castings are subjected can contribute to more safe designing and. consequently, to avoidance of too complicated moulds designs.

• The possibility of reliable strength analysis can promote application of the metallic moulds processes to •difficult castings and alloys. The iron alloys seem to be of particular interest here, although the material constants appearing in the constitutive model involved in the calculations would require some preparation.

Ст. преподаватель___________________________Л.А.Хилькевич

Одобрено на заседании кафедры 15.05.98

протокол №10