Notes and commentary

green sand (damp sand) – сырой песок sand of somewhat coarse grain – крупнозернистый песок and then baking the mixture dry – а затем высушиванием смеси are usually made up one day – обычно заготавливаются днем baked overnight – высушиваются за ночь assembled and cast the next day – сборка и литье происходит на следующий день skin-dried mold – форма, высушенная с поверхности dry-sand bond – сухой песок в качестве связующего вещества partial mold – частичная форма (неполная форма) the remaining portion of the mold is completed with green-sand – остальная часть формы заполняется сырым песком are kept in stock – имеется в качестве сырья

should be very fine to bring out this detail – должен быть очень мелким, чтобы воспроизвести эту деталь come off through – выходить (удаляться) через песок bench work – верстачная работа light floor work – негромоздкая работа less fine – более крупный is high in silica – содержащий много кварца for a long time after – долгое время после which makes a strong bond – который действует как сильное связующее вещество facing materials – припылы comes in contact – соприкасается the object is to give a smooth surface to – этот элемент должен придавать поверхности гладкость

Exercises

1. Read the sentences and say whether they are true or false.

1. There are four classes of materials for molding that are kept in stock in the foundry.

2. Medium sand is used for the castings such as stove plate.

3. Heavy sand is used for very large iron and steel castings.

4. Dry-sand molds are usually made up two days.

5. Dry-sand molds are recommended for aluminium castings.

2. Make up sentences out of these words.

1. carbon, facing, forms, are, different, purposes, used, of, for.

2. Sand, three, method, molds, making, are, principal, there, of.

3. With, portion, completed, green, when, the mold, mold, the, sand, the, partial, of, is, dry, remaining, is.

4. Are, overnight, molds, dry-sand, usually, baked.

Stove, for, light, such, sand, the, plate, castings, used, is, as.

3. What is the Russian for these words and word combinations?

1. facing materials

2. clay-bonding material

3. silicon dioxide

4. to resist the heat

5. graphite for blacking

6. to give a smooth surface

7. the remaining portion

8. mixed with dry-sand bond

9. glow and give off gases

10. small amount of water

Unit 6. TYPES OF MOLDING MACHINES

Modern molding machines successfully perform a consider­able amount of work that was done by hand.

Those molding machines that are used primarily for pack­ing sand in flasks can be classified as squeezer machines, jar (or jolt) machines, jolt squeezers, and sand slingers. Other types of machines employed in molding are pattern-draw ma­chines (stripping-plate machines and stripper machines) roll­over machines, combination machines, vibrators, and others.

The squeezer machine rams sand into the flask, which is placed between the machine table and an overhead plate, thus obtaining uniform density of the sand contained in the flask.

The jar or jolt machine consists of a rugged base cylinder and piston which is attached to the machine table. The table is lifted by air pressure directed against the piston from below, and is then permitted to drop. This action produces a jar which rams the molding sand evenly in the flask. The operation is very rapid, and some of the jolt machines used for small flasks give more than a hundred blows per minute.

The jar-squeezer machine, also called the jolt-squeezer ma­chine, combines the operating principles of the jolt machine and the squeezer machine. A complete mold, drag and cope, is produced by means of this machine.

Machines called sand slingers are sand-filling and ramming devices used in the rapid molding of large castings. These machines can be used in combination with other molding de­vices such as the roll-over machine and the pattern-draw ma­chine.

Machines of various kinds have been developed for the purpose of drawing pattern out of the mold. There are two types of pattern-drawing machines: the stripping-plate machine and the stripper.

In the stripping-plate machine, the pattern is fitted through a plate that fits accurately around the pattern. The patterns are drawn through the plate, either by moving the pattern supports down with a lever or by raising the plate and the mold half up, free from the pattern. The stripping-plate machine is best adapted to that class of work which offers difficulties in drawing the pattern from the sand.

A stripper is a machine that either lifts the mold away from the pattern or lifts the pattern away from the mold.