Упражнения

Упр. 1. Найдите в тексте английские эквиваленты слов и словосочетаний:

1. Невооруженным глазом, 2. доступ, 3. обнаруживать, 4. цветная дефектоскопия, 5. разбрызгивать, 6. краска, 7. рентгеноскопия, 8. по заданной траектории, 9.усиливать, 10. пузырьки газа, 11. амплитуда, 12. фоновые помехи, 13. магнитный поток, 14. прямой угол, 15. магнитный полюс

Упр.2. Переведите на РЯ следующие слова и выражения из текста:

1. Undercutting, 2. reverse side, 3. excess penetration, 4. liquid penetrant inspection, 5. surface cracking, 6. the weld vicinity, 7. penetrating properties, 8. sub-surface crack, 9. critical joints, 10. flaw, 11. discontinuity, 12. ferro-magnetic material, 13.magnetic flux, 14. longitudinal crack, 15. leakage area

Упр.3. Переведите на РЯ:

1. На начальном этапе выявления дефектов проводится внешний осмотр. 2. Некоторые дефекты можно обнаружить невооруженным глазом. 3. Для цветной дефектоскопии используется жидкий краситель с хорошей проницаемостью. 4. рентгеноскопия – дорогой, но эффективный метод выявления трещин. 5. Звуковой луч высокой частоты направляют на изделие. 6. Место дефекта определяют по задержке времени отражения луча. 7. Неопытный оператор может спутать отражение луча от незначительного дефекта и фоновые помехи. 8.Когда силовые линии магнита достигают трещины, они отклоняются и уходят через поверхность. 9. Намагниченный порошок обозначает место разрыва. 10. Магнитный поток проходит под прямым углом к направлению движения тока.

Unit 18. SPOT WELDING

Spot welding is a type of resistance welding used to weld various sheet metals. Typically the sheets are in the 0.5-3.0 mm thickness range. The process uses two shaped copper alloy electrodes to concentrate welding current and force between the materials to be welded. The result is a small spot that is quickly heated to the melting point, thus forming a nugget of welded metal after the current is removed. The amount of heat released in the spot is determined by the amplitude and duration of the current. The current and duration are chosen to match the material, the sheet thickness and type of electrodes. Applying the current for too long can result in molten metal being expelled as weld splash, or can even burn a hole right through the materials being welded.

Spot welding is normally used when welding particular types of metal steel sheet. Thicker stock is difficult to heat up from a single spot, as the heat can flow into the surrounding metal too easily. Spot welding can be easily identified on many sheet metal goods, such as metal pails, (buckets). Aluminum alloys can be spot-welded too. However, their much higher thermal and electrical conductivity mean that up to three times higher welding currents are needed. This requires larger, more powerful and more expensive welding transformers..

Due to changes in the resistance of the metal as it starts to liquefy, the welding process can be monitored in real time to ensure a perfect weld every time, using the most recent advances in monitoring \feedback control equipment. The resistance is measured indirectly, by measuring the voltage and current through the electrodes.

The voltage needed for the welding depends on the resistance of the material to be welded, the sheet thickness and desired size of the nugget. When welding a common combination like 1.0+1.0 mm sheet steel, the voltage between the electrodes is only 1.5 V at the start of the weld but can fall as low as 1.0 v at the end of the weld this drop in voltage stems from the resistance reduction caused by the steel melting. The open circuit voltage from the transformer is much higher than this, typically in the 5-10V range, but there is a very large voltage drop in the electrodes and secondary side of the transformer when the circuit is closed.

Perhaps the most common application of spot welding is in the automobile\ car manufacturing industry, where it is used almost universally to weld the sheet metal to form a car. Spot welders can also be completely automated, and many of the industrial robots found on the assembly lines are spot welders, the other major use for robots painting. A further place where spot welding is used is in the orthodontist’s clinic, where small scale spot welding equipment is employed when resizing metal “molar bands” used in dentistry.

VOCABULARY

Resistance welding – электрическая контактная сварка

Sheet metal – (тонко)листовой металл

Shaped electrode – электрод особого профиля

Nugget – ядро сварной точки

Amplitude - амплитуда

Weld splash – выплеск металла

Stock - сырье

Thermal conductivity - теплопроводность

Electrical conductivity - электропроводность

Transformer - трансформатор

Liquefy – разжижать\ся

Control equipment – контрольно-измерительное оборудование \ приборы

Feedback – обратная связь

УПРАЖНЕНИЯ

Упр.1. Найдите в тексте английские эквиваленты следующих слов и словосочетаний:

1.Электроды из медных сплавов; 2. температура плавления; 3. длительность воздействия электротока; 4. прожечь сквозное отверстие в материале; 5. тепло легко проникает в окружающий металл; 6. литое ядро сварной точки; 7. необходим ток почти в три раза большей мощности; 8. за процессом сварки можно следить в реальном времени; 9. ток, проходящий через электроды; 10. падение напряжения происходит из-за снижения сопротивления.

Упр.2. Переведите на английский следующие слова и словосочетания:

1. In the 0.5-3.0 mm thickness range; 2. a nugget of welded metal; 3. the amount of heat released; 4. expelled as weld splash; 5. particular types of metal steel sheets; 6. desired size of the nugget; 7. a very large voltage drop; 8. car manufacturing industry’ 9. orthodontist’s clinic; 10. small scale welding equipment.

Упр.3. Переведите на английский следующие предложения:

1.Тепло для контактной сварки получают при прохождении тока через контактную часть электродов. 2. Точечная сварка – это разновидность контактной сварки. 3. Контактная сварка легко поддается автоматизации и механизации. 4. Точечная сварка широко применяется в автомобилестроении. 5. Прохождение тока вызывает разогрев и расплавление металла в зоне сварки, в результате чего создается ядро сварной точки. 6. Точечная сварка представляет собой особый процесс, в котором расплавление металла сочетается с использованием значительного давления. 7. Диаметр сварного ядра определяет прочность точки. 8. Диаметр ядра зависит от диаметра рабочей поверхности электрода, толщины свариваемых листов, давления, силы тока и длительности его воздействия. 9. Слишком длительное воздействие тока может привести к выплеску металла. 10. Напряжение для точечной сварки зависит от сопротивления свариваемых материалов.

Unit 19. OXY-GAS TORCHES

Regulators

The torch is the part that the welder holds and manipulates to make the weld. It has a connection and a valve for the fuel gas and a connection and a valve for the oxygen, a handle for the welder to grasp, a mixing chamber, set at an angle, where the fuel gas and oxygen mix, with a tip where the flame forms.

There are different types of torches. A cutting torch is used to cut metal. It is similar to a welding torch. The most common fuel used for cutting torches is acetylene. Oxygen is mixed with the acetylene in the torch which produces a high temperature flame. The differences between a cutting torch and a welding torch are:

1. The mixing chamber with flame nozzle is more heavily built and set at 90º.

2. There is a third tube from the torch valves to the mixing chamber. It carries high-pressure oxygen, controlled by a large trigger lever on the torch.

In most torches the two gases merely mix: this is an equal-pressure torch. But in some torches, called injector torches, inside the torch head the oxygen comes out of a small nozzle under pressure so it drags the fuel gas along with it.

The regulators are attached one each to the fuel source and to the oxygen source. The oxygen regulator is attached to the oxygen tank and drops the pressure from about 21000 kPa (200 atmospheres) to a lower pressure for the torch. This pressure can be adjusted to suit the job at hand by turning a knob on the regulator and can be set from 0 to about 700 to 1400 kPa. Likewise the fuel regulator is attached to the fuel source and drops the pressure to a level for the torch to use. Most regulators have two gauges: one indicates the cylinder pressure when the valve is opened; the other indicates the pressure of the gas coming out of the regulator when the regulator is opened. This is the delivery pressure of the gas, which must be set for the current job. The gauges are calibrated to read correctly at 21º C.

These regulators can be single-stage and double-stage. A single-stage regulator mechanism consists of a nozzle that the gas passes through, a valve seat to close off the nozzle, a diaphragm and balancing springs. These mechanisms are all enclosed in a suitable housing. Fuel gas regulators and oxygen regulators are basically of the same design, but fuel gas regulators, except for hydrogen, are not made to withstand the high pressure that oxygen regulators are subjected to.

In the oxygen regulator the oxygen enters through the high pressure inlet connection and passes through a glass wool filter that removes dust and dirt. Turning the adjusting screw in (clockwise) increases the oxygen flow. The major disadvantage of single-stage regulators is that you must constantly monitor and reset the regulator if you need a fixed pressure and a flow rate.

The double-stage regulator is similar in principle, the main difference being that the total pressure drop takes place in two stages instead of one. In the high pressure stage, the cylinder pressure is reduced to an intermediate pressure that was predetermined by the manufacturer. In the low-pressure stage, the pressure is again reduced from the intermediate pressure to the working pressure you have chosen.

Regulators are precise and complicated pieces of equipment. Carelessness can do more to ruin a regulator than any other gas-using equipment. One can easily damage a regulator by simply forgetting to wipe clean the cylinder, regulator or hose connections. When you open a high pressure cylinder, the gas can rush into the regulator at the speed of sound. If there is any dirt in the connections, it will be blasted into the precision-fitted valve seats, making them leak. This results in a condition known as creep, which occurs when the regulator is shut off but not the cylinder, and gas pressure is still being delivered to the low-pressure side.

Oil or other petroleum products of fat or biological origin must never be used around oxygen regulators because these products may cause a regulator explosion or a fire.

VOCABULARY

Regulator – редуктор, регулятор

Valve - вентиль

Fuel gas – горючий газ

Connection – штуцер, соединение

Mixing chamber – смесительная камера

Tip - конец

Cutting torch - резак

Acetylene - ацетилен

Trigger lever – пусковой рычаг

Equal pressure torch – безинжекторная горелка

Injector torch – инжекторная горелка

Gauge - манометр

Delivery pressure – рабочее давление

One-stage torch – однокамерный редуктор

Double stage regulator – двухкамерный редуктор

Nozzle – наконечник, мундштук

Balancing spring – балансировочная \уравнительная пружина

Diaphragm - диафрагма

Housing - корпус

Inlet connection – входной штуцер

Adjusting screw – регулировочный вентиль

Hose connection – шланговое соединение, ниппель

Leak – нарушение герметичности, утечка

Creep – утечка, разгерметизация