Задание 4: Прочитать и перевести




Дата: 13.04.2020 (2часа)

ОСАТП- 1подгр.

(49, 50)

ТЕМА: Практическое занятие «Пластик». Практическое занятие «Литье и ковка металлов».

Цель: Совершенствование навыков ознакомительного чтения, перевода текста и навыков письменной речи.

Задачи:

Дидактические:

обучающийся должен знать:

- правила построения простых и сложных предложений на профессиональные темы;

- основные общеупотребительные глаголы (бытовая и профессиональная лексика), лексический минимум, относящийся к описанию предметов, средств и процессов профессиональной деятельности;

- особенности произношения, правила чтения текстов профессиональной направленности.

обучающийся должен уметь:

- понимать общий смысл четко произнесенных высказываний на известные темы (профессиональные и бытовые);

- понимать тексты на базовые профессиональные темы;

- участвовать в диалогах на знакомые общие и профессиональные темы, строить простые высказывания о себе и о своей профессиональной деятельности;

- кратко обосновывать и объяснить свои действия (текущие и планируемые);

- писать простые связные сообщения на знакомые или интересующие профессиональные темы.

Развивающие:

(метапредметные)

- создать условия для расширения кругозора студентов и обогащения их словарного запаса; - создать условия для развития памяти, логического мышления

Воспитательные:

(личностные) содействовать формированию положительного отношения к изучаемому предмету

Задание 1: Изучить лексический материал по теме «Пластик».

fibre — волокно, нить

identical — одинаковый, идентичный

branch — разветвленный

to synthesize — синтезировать

to soften — смягчать

cellulose — клетчатка, целлюлоза

wax — воск

thermosetting plastics — термореактивные пласт­массы

to harden — делать твердым

coil — спираль

stretched — растянутый

transparent — прозрачный

rubber — резина, каучук

to decompose — разлагаться

soft-drink — безалкогольный напиток

to subject — подвергать

polyurethane — полиуретан

resin — смола

similar — сходный, подобный

sufficient — достаточный

to prevent — предотвращать

 

 

Задание 2: Выполнить перевод текста

Plastics

 

Plastics are non-metallic, synthetic, carbon-based materials. They can be moulded, shaped, or extruded into flexible sheets, films, or fibres. Plastics are synthetic polymers. Polymers consist of long-chain mole­cules made of large numbers of identical small molecules (monomers). The chemical nature of a plastic is defined by the monomer (repeating unit) that makes up the chain of the polymer. Polyethene is a polyolefin; its monomer unit is ethene (formerly called ethylene). Other catego­ries are acrylics (such as polymethylmethacrylate), styrenes (such as polystyrene), vinys (such as polyvinyl chloride (PVC)), polyes­ters, polyurethanes, polyamides (such as nylons), polyethers, acetals, phenolics, cellulosics, and amino resins. The molecules can be either natural — like cellulose, wax, and natural rubber — or synthetic — in polyethene and nylon. In co-polymers, more than one monomer is used.

The giant molecules of which polymers consist may be linear, branched, or cross-linked, depending on the plastic. Linear and branched molecules are thermoplas­tic (soften when heated), whereas cross-linked molecules are thermosetting (harden when heated).

Most plastics are synthesized from organicchemicals or from natural gas or coal. Plastics are light-weight com­pared to metals and are good electrical insulators. The best insulators now are epoxy resins and teflon. Teflon or polytetrafluoroethene (PTFE) was first made in 1938 and was produced commercially in 1950.

Plastics can be classified into several broad types.

1. Thermoplastics soften on heating, then harden again when cooled. Thermoplastic molecules are also coiled and because of this they are flexible and easily stretched.

Typical example of thermoplastics is polystyrene. Polystyrene resins are characterized by high resistance to chemical and mechanical stresses at low temperatures and by very low absorption of water. These properties make the polystyrenes especially suit­able for radio-frequency insulation and for parts used at low temperatures in refrigerators and in airplanes. PET (polyethene terephthalate) is a transparent thermoplas­tic used for soft-drinks bottles. Thermoplastics are also viscoelastic, that is, they flow (creep) under stress. Ex­amples are polythene, polystyrene and PVC.

2. Thermosetting plastics (thermosets) do not soften when heated, and with strong heating they decompose. In most thermosets final cross-linking, which fixes the molecules, takes place after the plastic has already been formed.

Thermosetting plastics have a higher density than thermoplastics. They are less flexible, more difficult to stretch, and are less subjected to creep. Examples of ther­mosetting plastics include urea-formaldehyde or polyurethane and epoxy resins, most polyesters, and phenolic polymers such as phenol-formaldehyde resin.

3. Elastomers are similar to thermoplastics but have sufficient cross-linking between molecules to prevent stretching and creep.

Задание 3: Ответить на вопросы по тексту

 

1. What are plastics?

2. What is the chemical nature of plastics?

3. What are the best insulators now?

4. What is PET?

5. How can plastics be classified?

Задание 4: Прочитать и перевести

Metal processes

Casting is a 6,000-year-old process. It is the oldest and most well-known technique based on three fundamental steps: moulding, melting and casting. First the pattern is made to form the mould. Then an empty mould is created, and finally the empty cavity is filled with molten metal which is then left to solidify into the shape. Casting materials are usually metals but can also be plastic, resin or various cold materials for example concrete. Casting is usually used for making complex shapes.

Drawing is a manufacturing process for producing wires, bars and tubes by pulling on material through a series of dies until it increases in length. It is divided into two types: sheet metal drawing, and wire, bar and tubedrawing. Drawing is usually done at room temperature but it can be performed at elevated temperatures to hot work large wires, rods or hollowsections in order to reduce forces.

Forging is the process by which metal is heated and shaped by a compressive force using a hammeror a press. It is used to produce large quantities of identical parts, such as machine parts in the automobile industry. Cold forging is done at a low temperature using soft metals and plastic. Hot forging is done at a high temperature and makes metal easier to shape without breaking. In the past, forging was done by a blacksmithusing a hammer. Nowadays industrial forging is done with presses powered by a machine.

Rolling is a metal forming process in which a material (metal, plastic, paper or glass) is passed through a pair of rollers. According to the type of material rolled, there is hot rolling or cold rolling.

Extrusion is a process used to produce objects with a fixed cross-sectional profile. A material is pushed or drawn through a die of the desired cross-section. The two main advantages of this process are its ability to create very complex cross-sections and work materials that are brittle. The extrusion process can be done with hot or cold materials. Commonly extruded materials include metals, polymers, ceramics, concrete and foodstuffs.

Ceramic can also be formed into shapes via extrusion. Terracotta extrusion is used to produce pipes. Many modern bricks are also manufactured using a brick extrusion process. Extrusion is also used in food processing. Products such as certain pastas, many breakfast cereals, French fries, dry pet food and ready-to-eat snacks are mostly manufactured by extrusion.

Sheet metal forming is simply metal formed into thin and flatpieces. The basic forms can be cut and bentinto a variety of different shapes. Everyday objects are constructed with this process. There are many different metals that can be made into sheet metal, such as aluminium, brass, copper, steel, tin, nickel and titanium. For decorative uses, important sheet metals include silver, gold, and platinum. Sheet metal forming is used in car bodies, airplane wings and roofs for buildings.

 

Задание 4: Ответить на вопросы по тексту

1. Which steps are included in casting?

2. What is the mould used for?

3. What does drawing use in order to process metals?

4. What types of drawing are there?

5. What kind of process is forging?

6. How was forging done in the past?

7. What does rolling consist of?

8. What materials can be used in rolling?

9. What are the advantages of extrusion?

10. What materials can be used in extrusion?

11. What kind of process is sheet metal forming?

12. What can vary in sheet metal forming?

 



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