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1. There are different types of welding. 2. Resistance welding process forms a whole group. 3. Welding process are classified according the source of energy. 4. Gas welding is normally used to join steel to steel. 5. They are welted by an electric arс. 6. In gas welding, it is necessary to use a mixture of 2 gases. 7. In arc welding the work pieces are not melted by a flame. Посмотрите на рис. 5, 6, 7 в Приложении Е и назовите пронумерованные части сварочной установки. 19. Переведите текст. Arс Welding 1. In arc welding the workpiece are not melted by a flame. They are melted by an electric arc. In order to create the arc, a powerful electric current must be provided. 2. The current must be at least 60 A, otherwise the arc will not create enough heat. For thicker workpieces, the current may be 250 A. In order to carry this current, the cables from the transformer should be quite thick or else they will overheat. 3. To supply the necessary current the transformer is used and to complete the electric circuit an earth clamp is used, which is attached to the workpiece. Then the current flows around the circuit and the arc appears. It must be securely attached, otherwise an arc will appear between the clamp and the workpiece. To strike the arc, the transformer should be switched on first. 4. The electrode holder contains an electrode rod which provides the filler metal to join the workpiece. As the current flows between the electrode and the workpiece, the tip of the electrode melts and falls onto the workpiece. The electrode must be moved across the joint continuously, if it is moved too quickly neither the electrode nor the workpiece will melt. 5. While choosing an electrode type it is necessary to know: a. Position to which the workpiece is to be welded. b. Type and thickness of metal used. c. Type of welding current. d. Class of work: deep penetration, surface quality, etc. Прочитайте текст и выполните следующие за ним упражнения. 2. Переведите встречающиеся в тексте интернациональные слова и сгруппируйте их по частям речи: Electric, cable, transformer, electrode, type, position, metal, class. 3. Определите, к какой части речи относятся следующие слова: Workpiece, flame, electric, trey, transformer, securely, to appear, holder, continuously, melt, thickness, penetration, quality, powerful. Расставьте следующие слова в алфавитном порядке. Order, arc, powerful, otherwise, supply, earth, clamp, attach, use, flows, appear, should, be, class, type, deep, penetration, welding, current. Из предыдущего упражнения выберите слова, образованные аффиксацией и переведите их на русский язык, соблюдая части речи.
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