ІІ. Read and translate the text:

The finest grades of steel are produced by the electric furnace method. Stainless and heat resistant steels are made almost exclusively by that process.

Electricity is used only for the production of heat and does not of itself impart any superior quality of steel. Nevertheless, the electric furnace method gives certain advantages impossible in other steel melting processes. The electric furnace generates extremely high temperatures. The temperature is at all times under precise control and is easily regulated.

  The production of heat by electricity is unique, oxygen is not necessary to support combustion and the atmosphere within an electric furnace may be regulated at will.

   The electric furnace is a circular steel shell resembling a huge tea-kettle in general appearance. It is mounted on rockers so that the furnace can be tilted to pour off molten metal and slag. The bottom f the furnace consists of a layer of heat resistant materials below which it is lined with refractory bricks. The side walls which are also lined with refractory bricks contain three or more openings.

  The roof of the furnace is lined with 250 mm or more of refractory brick and is shaped like a flat dome. Through this dome great columns of carbon reach into the furnace. These are the electrodes which carry the current to the steel charge.

 

III. Answer the following questions:

1. What is the Electric Furnace?

2. Where are made stainless and hear resistant steels?

3. Why electricity is used in producing the steel?

OTHER CASTING PROCESSES

I. Read and memorize the following words:

process [´prousəs] процес, метод

fluid [´flu:id] рідкий

is poured [´pɔ:d] наливається

core [kɔ:] серцевина

external [eks´tə:nəl] зовнішній

pressure [´preʃə] тиск

suitable [´sju:təbl] підходящий

lead [led] свинець

zinc [ziŋk] цинк

aluminium [ælju´minjəm] алюміній

magnesium [mæg´ni:zjən] магній

alloy [´ælɔi] сплав

certain [´sə:tn] певний

bronze [brɔnz] бронза

unit [´ju:nit] одиниця, комплект

coating [´koutiŋ] покриття

pouring [´pɔ:riŋ] виливання

ejection [i:´ʤekʃn] викидання

are performed [pə´fɔ:md] виконуються

placing [´pleisiŋ] розташування

preheated [´pri:´hi:id] попередньо нагріваються

blowhole [´blouhoul] газова куля

oxide [´ɔksаid] окись

to foul [fаul] забруднювати

die [dаi] штамп, прес-форма

essentially [i´senʃəli] по суті

the same [seim] той самий

except [ik´sept] крім того, що

are replaced [ri´pleist] замінюють

to employ [im´plɔi] використовувати

technique [tek´ni:k] техніка

to produce [prə´dju:] виробляти

to apply [ə´plаi] використовувати

surface [´sə:fis] поверхня

to require [ri´kwаiə] вимагати

to furnish [´fə:niʃ] здійснювати

required [ri´kwаiəd] який потрібно

forcing [´fɔ:siŋ] нагнітання

rapid [´ræpid] швидкий

centrifugal [sen´trifjugəl] центробіжний

mold [mould] форма, ізложниця

to rotate [rou´teit] обертатись

to direct [di´rekt] направляти

solidification [səlidifi´keiʃn] твердіння

to occur [ə´kə:] траплятися

especially [ is´pe] особливо

such as [´sʌtʃ `æz] такі, як

sleeves [´sli:vz] муфта, втулка

cylindrical [si´lindrikəl] циліндричний

since [´sins ] так як

part [pα:t] деталь

to require [ri´kwаiə] вимагати

to design [di´zаin] конструювати

because of [bi´kɔ:z] через

engine [´enʤin] мотор

device [di´vаis] механізм

product [ ´prɔdǝkt] виріб

technique [tek´ni:k] техніка

 

II. Read and memorize the following phrases:

permanent-mold-casting process – метод лиття у постійні форми

cast-iron – чавун

a number of – багато

mounted on a turntable – змонтовані на обертаючому столі

as each mold passes certain stations – по мірі того, як форма проходить

                         певний пункт

a dense fine-grained structure – щільну дрібнозернисту структуру

shrink hole – усадочна раковина

free from…. – вільну від

yellow brass – латунь з високим вмістом цинку

semi - permanent mold process – метод лиття у напівпостійні форми

sand core – піщаний сердечник

die-casting process – метод лиття в прес-формах

previously described – раніше описаний

to force the molten metal into the metallic molds or dies – нагнітати

розплавлений метал у металеві форми або штампи

in order to – для того, щоб

accurately shaped and dimensioned parts – точні по формі та розмірам

  деталі

little machining – невелика обробка

die-casting machine – машини лиття під тиском

complete cycle – повний цикл

consumes less than one minute – потребує менше хвилини

fairly rapidly – достатньо швидко

due to the rotation – завдяки обертанню

centrifugal forces – центр обіжні сили

are being developed – розвиваються

incoming liquid metal – рідкий метал, який поступає

inner surface – внутрішня поверхня

considerable intensity – значна інтенсивність

greater accuracy – велика точність

superior physical properties – кращі фізичні властивості

as compared with that produced by gravity sand casting – порівняно з

продуктом, який отримуємо за допомогою лиття у грунт під тяжкістю

symmetrical shape – симетрична форма

cast-iron pipes – чавунні труби

centrifugal coasting – центр обіжне лиття

precision casting – точне лиття

manufacturing advantages – виробничі переваги

die-casting – лиття під тиском

to a degree – до деякого ступеня

permanent-mold casting – лиття у кокіль

are regarded as – вважаються

so produced – вироблені таким чином

makes it possible – дозволяє

complex shape – складна форма

difficult to machine – важко обробляти

hard or tough quality – твердаабо жорстка якість

component parts – складові частини

must withstand – повинні витримувати

hard service – жорсткі умови експлуатації

III. Read and translate the text:

  In the permanent-mold-casting method, fluid metal is poured into metal molds and around metal cores without external pressure.

  Metals suitable for this type of casting are lead, zinc, aluminium and magnesium alloys, certain bronzes, and cast-iron.

  For making iron castings of this type, a number of metal mold units are usually mounted on a turntable. The individual operations, such as coating the mold, placing the cores, closing the mold, pouring, opening the mold, and ejection of the casting, are performed as each passes certain stations. The molds are preheated before the first casting is poured. The process produces castings having a dense fine-grained structure, tree from shrink holes or blowholes.

Yellow brasses, which are high in zinc, should not be cast by the permanent-mold process because the zinc oxide fouls the molds or dies.

Semi-permanent mold process is essentially the same as that of the permanent mold, except that the metal cores are replaced by sand cores.

Die-casting process employs the permanent-mold technique previously described, except pressure is always applied in order to force the molten metal into the metallic molds or dies.

  This process produces accurately shaped and dimensioned parts surfaces of which require very little machining.

  Die-casting machines of various design are used to hold the dies and to furnish the pressure required for forcing the liquid metal into the dies. These machines furnish an automatic cycle of operation which is rapid and economical.

  The die-casting process is the most rapid of all casting methods, since its complete cycle consumes less than one minute.

  The principle of centrifugal casting is that mold rotates fairly rapidly while the molten metal is poured into it. Due to the rotation of the mold, centrifugal forces are being developed, which direct the incoming liquid metal to the inner surface of the mold with considerable intensity, where solidification occurs. This method of casting produces a product of greater accuracy and superior physical properties as compared with that produced by gravity sand casting. Centrifugal casting is especially good for products of symmetrical shape, such as cast-iron pipes, sleeves, and other castings of cylindrical form.

  Precision casting has many manufacturing advantages. Die-casting and, to a degree, permanent-mold casting are regarded as precision-casting methods, since parts so produced require little machining.

Precision casting makes it possible to design and produce parts of complex shape from metals and their alloys that are difficult to machine because of their hard or tough quality. Component parts of engines, machines, devices, and products which must withstand very high temperatures and hard service also may be produced by precision-casting techniques.

 

 

IV. Answer the following questions:

1. What are metals suitable for the permanent- mold-casting method?

2.What is the difference between permanent-mold-casting and semi-permanent mold processes?

3. What do you know about die-casting process?

4. What is the principle of centrifugal cast?