I. 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.
II. 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.
III. 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.
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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.
NOTES AND COMMENTARY
| modern molding machines – современные формовочные машины was done by hand – выполнялось вручную can be classified as squeezer ma chines – можно классифицировать как формовочные машины jar (jolt) machines, jolt sque ezers – встряхивающие машины, прессы sand slingers – пескометы pattern-draw machines – формовочная машина с протяжкой модели, протяжная машина stripping-plate machines – потяжная машина roll - over machines – формовочная машина с поворотной плитой combination machines – комбинированная машина to ram sand into the flask – набивать песок в опоку | overhead plate – подвесная плита directed against the piston from below –на поршень снизу and is then permitted to drop – а затем падает rams … sand evenly in – набивает песок равномерно a hundred flows per minute – сто ударов в минуту drag and cope – нижняя и верхняя опоки by means of – при помощи pattern is fitted through a pla te – образец захватывается плитой by moving the pattern supports down with a lever – путем опускания вниз опор модели рычагом adapted to – приспособлена к |
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EXERCISES
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