34. Укажите номера тех предложений, в которых сказуемое выражает долженствование. Переведите эти предложения

1) Coarse sand is to be used for producing large castings.

2) Cores are used to make hollows in castings.

3) The molten metal is first poured into the ladles, then into molds.

4) The amount of water in molding sand should not be too much.

5) Castings with coarse surface are to be cleaned in final operation.

6) The process of casting metals has been known for many centures.

7) Certain alloys have been prepared to make the qualities of molten metal better.

8) In order to produce the castings with high quality we should pay much attention to the preparation of alloys.

35. Прочтите внимательно и переведите на русский язык текст с Text c mold materials

Materials which are used for sand molds are refractory silica sand, bonding materials and facing materials.

Bonding materials is a suitable binder which is usually a form of clay.

Molding sand is a mixture of silica sand, a suitable binder and water. Sometime two or more bonding materials are mixed with silica sand.

Molding sands require the following characteristics: they must be refractory to withstand the high temperature of molten metals, porous and must have sufficient bond.

Notes to the text C:

silica – кварц, двуокись кремния

to bond – связывать, связывающее вещество, соединение

binder – связывающее вещество, крепитель, связь

sufficient – достаточный

facing – облицовочный песок, припыл

36. Запишите по-английски 3 термина, соответствующие русским. Поясните, выражают ли эти термины разные понятия или одно и то же

связующее вещество – …, связующий материал – …, крепитель – ….

37. Прочтите текст с ещё раз. Ответьте по-английски на следующие вопросы

1) What materials is this text about?

2) What materials are usually used binders?

3) What sand is used as mold material?

4) What components does the molding mixture contain?

5) What characteristics must the molding sand have?

38. Прочтите текст d, переведите его и скажите, о чём в нём говорится Text d

In order to give a smooth surface to the casting, facing materials are used. The usual method is to apply the facings fine powder to the surface of the mold after the pattern is taken out. The facing prevents the sand from sticking to the casting and also prevents the hot metal from burning into the sand. As a result, the sand separates easily from the casting when it is cold. Different forms of carbon, such as graphite, coke and sea coal are applied as facing.

Notes to the text D:

powder – порошок

to prevent from – предотвращать, мешать

to burn into – проникать, врезаться

to separate – отделяться

to apply – использовать, применять

coke – кокс, уголь

sea coal – цирконовый песок

39. Озаглавьте по-английски текст D.

40. Найдите в тексте D предложение, отвечающее на вопрос: What does the facing material prevent from?

41. Ответьте по-английски на следующие вопросы

1) What is the text D about?

2) What forms of facing do you know?

3) Where and when is the facing material applied?

4) Why is the facing material applied?

42. Прочтите внимательно текст E. Переведите его

Text E

Molding materials may be classified into some groups: molding sand, bonding material, facing and some others.

Molding sands may be light, medium and heavy. Light sand is used for castings which may have very finely produced detail on their surfaces. The sand should be very fine to bring out this detail. It must be strong so that the mold could retain every detail as the metal flows in.

Medium sand is used for making machinery castings having from ½ to 2 in. sections. The molding sand for this type of castings is coarser than those molded in light sand. The bond mixed with medium sand must be sufficiently strong to retain the shape of the mold. The large proportion of clay necessary for a strong bond makes the sand less porous. For the better sand porosity the sand of larger grain size is to be used.

Heavy sand is used for very large iron and steel castings. This sand is high in silica, and its grain is coarse to withstand the heat of the molten metal and the better porosity.

Notes to the text E:

light sand – тощая земля

medium sand – полужирная земля

heavy sand – жирная земля

to bring out – выполнять

to retain – сохранять

in. = inch – дюйм

section – сечение

grain – зерно, крупица