Упражнения

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

1.Дуговая сварка плавящимся электродом в среде инертного газа, 2. дуговая сварка плавящимся электродом в среде защитного газа, 3. дуговая сварка плавящимся электродом в среде активного газа, 4. источник постоянного тока,

5. цветные металлы, 6. полу-инертный газ, 7. двуокись углерода, 8. разнообразие, многосторонность применения, 9. дуговая сварка под флюсом, 10. защитный газ, 11. сварка порошковой проволокой (трубчатым электродом), 12. точечная сварка, 13. сварка электрозаклепками, 14. подключать, соединять, 15. включатель

II. Переведите на РЯ следующие слова и словосочетания:

1. Wire feed unit, 2. welding gun, 3. non-ferrous metals, 4. resistance spot welding, 5. dissipation, 6. conduit, 7. gas hose, 8. air volatility, 9. to alleviate a problem, 10. key parts, 11. to initiate the wire feed, 12. to strike the arc, 13. the conduit tip, 14. to reduce spatter, 15. to be firmly secured, 16. gas nozzle, 17. tanks of gas, 18. high

heat operation, 19. to drive (the electrode) through the conduit, 20. thermal conductiveness

III. Найдите в тексте синонимичны данным слова и выражения:

To decrease, control switch, welder, to employ a gas, widely, medium ot atmosphere, to start the wire feed, to initiate an arc, metal droplets, wire-feed unit

IV. Вставьте нужное слово или словосочетание:

1. Aluminum and copper are … metals. 2. Gas protecting the weld area is called a … gas. 3. GMAW is given preference for its speed and … . 4. The movement of the surrounding atmosphere can cause … of the shielding gas. 5. The problem can be … by increasing the shielding gas output. 6. The … initiates the wire feed. 7. The contact tip, made of copper, … the electrical energy to the electrode.8.Before arriving at the contact tip, the wire is protected and guided by the … . 9.The … is used to evenly direct the shielding gas into the welding area.

V. Дайте полную форму следующих аббревиатур:

GMAW, MAG,MIG, DCEN, DCEP, PAW

Unit 10. ULTRASONIC WELDING

Ultrasonic welding is an industrial technique whereby high-frequency ultrasonic acoustic vibrations are used to weld objects together, usually plastics, and especially for joining dissimilar materials. This type of welding is used to build assemblies that are too small, too complex or too delicate for more common welding techniques. In ultrasonic welding there are no connecting bolts, nails, soldering materials or adhesives necessary to bind the materials together.

For joining complex injection-molded thermoplastic parts, ultrasonic equipment can be easily customized to fit the exact specifications of parts being welded. The parts are sandwiched between a fixed shaped nest (anvil) and a sonotrode (horn) connected to a transducer which is lowered down, and a 20 kHz low-amplitude acoustic vibration is emitted. Common frequencies used in ultrasonic welding of thermoplastics are 15 kHz, 30 kHz, and 40 kHz. When welding plastics, the interface of the two parts is specially designed to concentrate the melting process. One of the materials traditionally has a spiked energy director which contacts the second plastic part. The ultrasonic energy melts the point of contact between the parts, creating a joint. This process is a good automated alternative to glue, screws or snap-fit designs. It is typically used with small parts, e.g. cell phones, consumer electronics, disposable medical tools, toys etc., but it can be used on parts as large as a small automobile instrument cluster. Ultrasonics can also be used to weld metals, but they are typically limited to small welds of thin, malleable metals, e.g. aluminum, copper, nickel. Ultrasonics would not be used in welding the chassis of an automobile or in welding pieces of a bicycle together, because of the power levels required.

Ultrasonic welding of thermoplastics causes local melting of the plastic due to absorption of vibration energy. The vibrations are introduced across the joint to be welded. Ultrasonic welding of metals is not due to heating, but instead occurs due to high-pressure dispersion of surface oxides and local motion of the materials. Although there is heating, it is not enough to melt the base materials. Vibrations are introduced along the joint being welded.

Ultrasonic welding appeared in mid-1960s and is rapidly developing. In its infancy only hard plastics could be welded because they were acoustically conductive and had a low melting point. Today ultrasonic welding machines have much more power, enough to weld less rigid, less acoustically conductive materials such as semi-crystalline plastics, as well as higher melting point materials. The patent for the ultrasonic method for welding rigid thermoplastic parts was awarded to R.Soloff in 1965.

An inevitable by-product of ultrasonic welding is a blast of ultrasonic sound. The lower frequencies of 15 kHz and 20 kHz typically emit a squeal that can be heard by operators. In many cases the noise level will exceed 80 dBa and therefore hearing protection is recommended when personnel are in close proximity to an ultrasonic welder. Welders using frequencies of 30 kHz and above do not normally emit a squeal audible to people in close proximity to the welder. It is widely accepted that most humans can hear ultrasonic noise as children but lose this ability around the late teens. A device known as “The Mosquito” which emits ultrasonic noise and is intended to break up groups of loiterers is being tested in the UK, mostly outside shops and other places where youths gather. However not all humans lose this ability so early and some never do. Persons who can hear ultrasonic sound would not be comfortable working in a factory or other environment where it is used without using hearing protection.

VOCABULARY

Ultrasonic - ультразвуковой

Connective – соединительный

To customize – доукомплектовать в соответствии с требованиями заказчика

Thermoplastic - термопластик

Anvil - наковальня

Sonotrode - сонотрод

Horn – рог (разрядник)

Transducer - преобразователь

Spiked energy director – заостренный директор энергии

Glue – клей

Adhesive – связующее, клейкое вещество

Snap-fit design - защелка

Cell phone – мобильный телефон

Consumer electronics – бытовая электроника

Disposable - одноразовый

Cluster – набор, комплект

Malleable – ковкий, пластичный, тянущийся

Automotive – передвижной

Power level – уровень мощности

Dispersion – дисперсия, рассеивание

Melting point – точка плавления

dB – децибел, единица измерения шума

dBa/dBA – децибел А (превышающий определенный уровень шума)