2. Определите по суффиксам, какой частью речи являются слова, предложенные вам справа. Догадайтесь о значении этих слов и переведите их

soft (мягкий) to shrink (усаживать) permeability (проницаемость) to desire (желать) common (обычный)

softness shrinkage permeable desirable commonly

3. Прочтите текст а, переведите его на русский язык и ответьте по-английски на следующие вопросы

1) Are there various types of sand molds?

2) What types of sand molds do you know?

3) What type of sand molds is most commonly used?

4) Are green-sand molds economical?

5) What materials are mixed for producing green-sand?

6) For what metals is green-sand molding recommended?

Text A

Castings are produced into different types of molds. The various types of molds for sand castings are classified as green-sand, skin-dried, dry-sand and air-dried molds.

Green-sand molds are most commonly used. Most of small castings are made in green-sand molds, as green-sand molding is economical and simple.

Green-sand molds are formed by mixing silica, clay and a small amount of water. The permeability of the sand must be high so that the steam and gases formed by heat of metal can escape through the mold. The damp molding sand is rammed around the pattern. When the pattern is withdrawn, the mold is finished. The mold may be poured as soon as made or it may be held over a day or more, depending upon its size. Greensand causes less cracks when the casting cool to room temperature.

Green-sand molds are softer and weaker than all other types of molds. This characteristic is desirable for complicated castings which have high solid shrinkage.

Green-sand molding is recommended for cast iron and is applied to large-quantity production.

Since large molds may require much time for making and assembling, some other type of mold is usually used for larger castings.

4. Выберите к русским терминам соответствующий английский эквивалент

форма, подсушенная с поверхности

a) air-dried mold; b) skin-dried mold

газопроницаемость

a) porosity; b) permeability

3. удалять

a) to withdraw; b) to dry

3. вызывать

a) to allow; b) to cause.

5. Вставьте вместо точек подходящее по смыслу слово

1) … sand is rammed in green – sand molding.

2) If steam and gases do not escape through the mold, they may … defects in the casting.

3) The time of pouring and assembling the mold depends upon … of the mold.

4) … large molds more time is usually required.

__________________________________________________________________

the size; to assemble; damp; to cause.

6. Закончите следующие предложения подходящим по смыслу термином

1) There are different types of sand molds, such as green-sand molds, air – dried molds, skin-dried molds and ….

2) The mixture for damp molds consists of clay, water and ….

3) The damp molding sand is packed around ….

4) Green – sand molds are weaker than ….

7. Определите, какой частью речи является подчеркнутое слово. Переведите предложения

1) Dry sand must be used for dry-sand molds.

2) Different methods may be used to dry the sand mold.

3) Steam and gases cause defects in the form of blowholes.

4) Silica sand, clay and water form the green-molding mixture.

5) Too rapid cooling may be the cause of forming cracks.

8. Распределите пункты плана в последовательности, соответствующей содержанию текста А. Запишите этот план

a) Types of sand mold.

b) Application of green-sand mold.

c) Properties and advantages of green-sand mold.

d) The process of producing damp molds.

e) The time of pouring damp molds.

9. Перескажите по-английски текст А по плану предыдущего упражнения.

10. Прочтите текст В и переведите его на русский язык

Text B

When the entire mold is dried, it is known as a «dry – sand mold». It is formed by mixing sand, bonding material and water. These molds have a hard surface and produce little gas or steam during casting.

They are stronger than green-sand molds. Dry-sand molds allow the use of finer sands with lower permeability, since nearly all of the moisture is removed. This produces smoother surfaces on the castings.

Dry – sand molds are usually made up one day, dried overnight, and assembled and cast the next day.

The drying is usually done in large ovens at temperatures about 450 degrees of Fahrenheit. Drying can also be done on the foundry floor using heated air or torch.

Dry – sand molds require the use of metal flasks because heat is used to dry them.

Dry – sand molds are recommended for steel castings and may be also used for many types of non-ferrous castings.

Since dried molds are more expensive than green-sand molds, they are used only when green-sand molds would be unsatisfactory.

Unknown words to the text B:

entire – весь; вся

moisture – влага

overnight – ночью

oven – печь

torch – горелка; пламя; факел

… on the foundry floor – на плацу (полу)

would be unsatisfactory – не удовлетворяют требованиям.

11. Ответьте по-английски на следующие вопросы, используя текст В

1) What materials are used for producing dry – sand molds?

2) How are usually dried dry-sand molds?

3) What is the temperature of ovens for drying these molds?

4) What flasks do dry-sand molds require?

5) In what cases are dry-sand molds recommended?

12. Поясните следующие фразы одним английским термином

a) to remove all moisture from the mold;

b) the property of sand to pass through gases and steam;

c) to put two halves of the mold together in finishing operation;

d) the sand with large amount of water.

13. Сравните по-английски сухие и сырые земляные формы, используя следующие вопросы и содержание текстов А и В

1) What molds (green-sand or dry – sand molds) are stronger?

2) What molds have harder surface?

3) What molds may produce smoother surface of the casting? Why?

4) Which molds are softer?

5) Which molds require higher permeability?

6) What molds are more expensive?

14. Прочтите текст С и скажите, о скольких и каких видах земляных форм идет в нем речь

Text С

Skin dried molds can be constructed economically by one of two methods. By the first method, silica sand is mixed with a dry – sand bond. The mixture is packed around the pattern to a depth of about ½ or 1 inch. Them the mold surface is dried by heat. When this part of the mold is dried, the remaining portion of the mold is completed with green sand.

By the second method the entire mold is constructed of green sand. Certain binders are added to this sand, and a stronger, harder surface is produced. The mold is then dried by air, oven or gas torch.

Air – dried molds remain open to the air for a certain period of time before closing. Some moisture escapes from the mold surfaces, making the mold harder. Large molds, such as pit molds, become air-dried while they are being made. Additional drying by heating may be done to remove any remaining moisture, and they would then become dry – sand molds.

Unknown words to the text C:

depth – глубина

to remain – оставаться

to complete – завершать, заканчивать

certain – определенный

to add – добавлять, дополнять

additional – добавочный, дополнительный

while – в то время как

pit – яма.