Прочтите, что обозначают следующие слова. Запомните их

dry – сухой

to dry – сушить

dry – sand mold – сухая форма; форма из сухой земли

f.e. Dry sand and dry bonds are often used to produce sand molds.

f.e. Dry – sand molds are usually used when castings of high quality are necessary.

f.e. Sand molds are dried by different methods.

green (damp) – sand – сырая земля

damp molding sand – сырая земля

green-sand mold – сырая форма; форма из сырой земли

damp-sand mold – сырая форма; форма из сырой земли

f.e. Damp sand is used for damp-sand molds.

f.e. Green – sand molds are widely used because of their low cost and simplicity of operation.

skin – dried mold – форма, просушенная с поверхности (соприкасающаяся с заливаемым металлом)

f.e. Skin-dried molds are used for certain types of sand castings.

f.e. Dry – sand mold, damp – sand mold, air – dried mold, skin – dried mold are types of sand molds for producing sand castings.

permeability – газопроницаемость

f.e. During ramming the permeability of green sand becomes lower.

to withdraw – удалять

f.e. The pattern is withdrawn when the sand has been properly rammed.

to cause – вызывать; производить; влиять (быть причиной)

f.e. The contact of hot metal with green – sand mold causes the forming of steam in the mold.

crack – трещина; раковина; закалочная трещина

cooling crack – трещина, возникающая при охлаждении

hot crack – трещина, возникающая при нагреве

weak – слабый

f.e. Too weak ramming causes defects in the casting.

complicated – сложный

f.e. When the casting must be large, a more complicated mold is required.

solid – твердый

solid shrinkage – усадка металла в твердом состоянии

f.e. Solid shrinkage takes place in the hot metal when it cools from solidifying temperature of the air.

quantity – сложный

f.e. For large quantity production mechanical means are used for making molds.

to assemble – собирать, монтировать

f.e. Too large molds are made and assembled on the floor.

f.e. The preparation and assembling of green sand and dry – sand molds is very much the same.

commonly – обычно.

 

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.