1. Answer the following questions

1 .What preliminary forging operations are discussed?

2. What are the primary functions of these operations?

3. Are all these preparatory operations always used in forging?

4. In which case doesn't the finishing impression represent the shape required for the finished forging?

5. Why shouldn't the importance of a competent design in the preliminary forging steps be underestimated?

2. Find the English equivalents for the following Russian word combinations

между каждым ударом

без какого-либо ограничения с двух сторон

без дальнейшей подготовки

завершённая поковка

с некоторыми изменениями в поперечном сечении

несоответствующий размер

где они необходимы

слишком резкий

уменьшить износ

что касается общих физических размеров

незначительная опасность

законы течения пластичного металла

последующие операции

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3. Match the words on the left with their definitions on the right

j)bender

2) edger

3) flash

4) fuller

5) blocking

6) impression

1. the portion of the die which is pri­marily used to reduce the cross-section of a portion in the forging stock between the ends of the stock

2. the metal that is in excess of that required to fill out the final im­pression in a pair of dies and moves out as a thin plate around the parting line of the dies

3. a forging operation which imparts to the forging its general but not exact or final shape

4. the portion of the dies which form the metal so that the longitudinal axis is in two or more planes

5. the portion of the die that distrib­utes the metal in a general propor­tion of the shape to be forged

6. the portion of the dies which has been machined to produce the shape of the forging

4. Translate at sight

1. Наиболее важной и широко распространённой предвари­тельной операцией ковки является обработка в формовочно-подкат-ном ручье.

2. Для предварительных операций ковки формовочно-под-катной и протяжной ручьи обычно используются одновременно.

3. В операциях предварительной ковки используются ручьи ковочного штампа, которые делятся на гибочные, черновые и чис­товые ручьи.

4. Операция сгибания обычно следует за такими операция­ми, как обработка в формовочно-подкатном ручье и вытяжка,

5. Использование чернового ручья помогает избегать дефек-^тов при ковке и значительно увеличивает долговечность штампа.

6. В большинстве случаев чистовой ручей имеет форму, тре-чУсмую для окончательной поковки.

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Unit 21

FORGING EQUIPMENT

The forging equipment may be divided into three classes: the hammer, the forging machine, the forging press.

The hammer has been known throughout the ages as the sym­bol of forging and today still occupies a prominent position in the forg­ing fields. The modern forging hammers are usually divided into three groups, namely, the drop hammer, the steam hammer, and the tilt or helve hammer.The drop hammer is the principal forging unit for the duplication of forged parts in the hammer field. These hammers are fit­ted with suitable drop forging dies to perform their work: Drop ham­mers are classified either as the steam drop or the board drop, depend­ing upon the method of power transmission.

The modern drop hammers consist of four major parts: the anvil, frequently called the base; the frames which rest upon the axis Bore fastened to the anvil; the head which is connected to the top of the frames and through which the power is delivered; and the ram which conveys the striking blow.

The dies are fastened to the ram and to the anvil cap. The anvil cap, also called the sow block, is placed between the bottom die and the anvil in order to protect the anvil from undue wear, as it is difficult to extract a heavy anvil from its foundation for remachining the work­ing surface. As the impact upon the die is transmitted to the sow block to wear it to a point where it is unfit for service, the sow block is easily removed and resurfaced by machining. The upper die is fitted directly to the ram, which can be removed from the hammer readily for ma­chining.

In the board drop and the steam drop hammers, the anvil, the frames, the guides, the ram, and the anvil cap are similar in shape and design, but due to the transmission of the operating power by different mediums and methods, the head for each type of hammer is different and distinctive from the other.

The original purpose of the forgoing machine was to gather or upset metal, first for bolt heads and later for general forging work.

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Today this type of forging unit produces a great variety of finished for-gings by the upset and displacement process. These forgings possess great accuracy and with well designed die equipment can be produced at a high rate of production. Forging presses are used extensively for a variety of forging work. For relatively small and medium sizes for­gings, the forging press is usually of the mechanical type. The largest forging work is invariably done on large hydraulic presses.

Exercises

1. Answer the following questions

1. What units are considered to be the principal forging equipment? 2- Into what groups are the modern hammers divided?

3. What are the main parts of a drop hammer?

4. For what purpose is a forging machine used?

5. Into what two groups are forging presses divided?

2. Find the English equivalents for the following Russian word combinations

помещается между нижним бойком и наковальней

различными средствами и методами

для размножения ковочных деталей

занимает видное место

чтобы защитить наковальню от чрезмерного износа

но вследствие передачи действующей силы

процессом высадки и смещения.

3. Translate at sight

1. Процессы ковки могут выполняться на молотах, ковоч­ных машинах и ковочных прессах.

2. Выбор нужного оборудования зависит от вида изготов­ляемого продукта и способности установки.

3. Самим старым типом ковочного оборудования являются молоты.

4. Разного типа молоты и сейчас широко используются в металлообрабатывающей промышленности.

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5. Современные ковочные машины широко используются для производства большого разнообразия изделий процессом вы­садки или процессом высадки и смещения.

6. Гидравлические прессы применяются при производстве больших изделий.

4. Match the words on the left with their definitions on the right

1) anvil a) steel blocks into which desired

impressions are machined and from which forgings are produced

2) ram b) a block of heat treated steel

placed between the anvil of the hammer and the forging die to prevent undue wear to the anvil

3) punch c) the forming process in which

metal stock is formed between dies, usually by hydraulic pres­sure

4) dies d) the movable die in a press or

forging machine

5) press e) a block of iron or steel upon

which metal is forged

6) sow block f) the moving part of a drop ham-

mer or a press to which one of the dies is fastened

Unit 22 EXTRUSION

The extrusion process has not been widely used for the production of steel tubes.The elevated temperatures essential to effect the necessary plasticity of a steel work piece require that the op­eration be rapid to avoid temperature drop and severe tool wear during the work stroke of the press. This requisite has resulted in the devel­opment of the practice known as «impact extrusion» in which the work

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stroke in extruding tubes 30 ft. long is completed in less than three seconds. In this process, either bored or solid rounds are heated and dropped into a cylindrical container, in the bottom of which a die is mounted directly below a crank or hydraulically operated plunger. When the solid rounds are used, a differentially actuating piercing punch is enclosed within the extrusion plunger. In operation, the weight of the extrusion plunger is allowed to rest on the upper surface of the work piece, while the piercing punch is forced through the work piece and die. When the end of the piercing punch has passed through the die, the piercing and extrusion plungers are locked together, per­mitting the piercing punch to act as moving mandrel, while the rapidly descending extrusion plunger forces the work metal through the annu­lar opening between the die and piercing punch. Pressures in excess of 90,000 psi are produced within the container. When the plungers have been withdrawn, a flash, which remains in the bottom of the container, is sheared off, thereby, releasing the extruded tube from the die.

When the bored rounds are used, the piercing punch is usually attached directly to the lower end of the extrusion plunger.

Because of the terrific pressure required, the application of the extrusion process to the manufacture of steel tubes has been limited to tubes less than 5 in. in diameter.

Exercises

1. Answer the following questions

1. Why do the elevated temperatures require that the operation of extrusion should be rapid?

2. What rounds are used in the extrusion process?

3. Why is the application of the extrusion process limited to the manufacture of steel tubes?

2. Find the English eguivalents for the following Russian word combinations

холодное прессование полых изделий («ударное истечение») резкий износ приспособления цилиндрический сосуд

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рабочий ход пресса

проколочный пуансон

нижний конец плунжера, кольцеобразное отверстие

движущаяся оправка

сверлёные круги

плунжер гидравлического действия

рерхняя поверхность обрабатываемой заготовки

цельные круги

избежать падения температуы