Перевести текст As a non-consumable electrodes tungsten or carbon electrodes can be used. In gas-tungsten arc welding a tungsten electrode is used in place of the metal electrode used in shielded metal-arc welding. A chemically inert gas, such as argon, helium, or carbon dioxide is used to shield the metal from oxidation. The heat from the arc formed between the electrode and the metal melts the edges of the metal. Metal for the weld may be added by placing a bare wire in the arc or the point of the weld. This process can be used with nearly all metals and produces a high-quality weld. However, the rate of welding is considerably slower than in other processes. Gas-Metal Arc In gas-metal welding, a bare electrode is shielded from the air by surrounding it with argon or carbon dioxide gas and sometimes by coating the electrode with flux. The electrode is fed into the electric arc, and melts off in droplets that enter the liquid metal of the weld seam. Most metals can be joined by this process. Submerged Arc Submerged-arc welding is similar to gas-metal arc welding, but in this process no gas is used to shield the weld. Instead of that, the arc and tip of the wire are submerged beneath a layer of granular, fusible material that covers the weld seam. This process is also called electroslag welding. It is very efficient but can be used only with steels. Resistance Welding In resistance welding, heat is obtained from the resistance of metal to the flow of an electric current. Electrodes are clamped on each side of the parts to be welded, the parts are subjected to great pressure, and a heavy current is applied for a short period of time. The point where the two metals touch creates resistance to the flow of current. This resistance causes heat, which melts the metals and creates the weld. Resistance welding is widely employed in many fields of sheet metal or wire manufacturing and is often used for welds made by automatic or semi-automatic machines especially in automobile industry. 1.What.I do to get a visa?(should,have,is,need) 2.She.cook delicious meals.(Can,must,have to,may) 3.It.snow tomorrow.(should,need,may,ought to) 4.you help me?(may,must,have to,could) 5.You.knock on the door to enter her room(may,ought,must,had to) 6.I.call a taxi because my car didn’t start.(could,might,had to,need) 7.They.to wear uniform at school.(doesn’t have,hadn’t,haven’t,didn’t have) 8.She.lose some weight to feel better.(may,have to,ought to,can) 9.He.obey the University rules.(don’t have,are to,must,doesn’t have) 10.The.were happy. Their had come true. Listen to the song and fill in the gaps from the box. Mother Earth, Mother. It’s a great. to be Mother Earth, Mother Earth home. for. and. It’s.place. In peace and. Look after our Earth. Cos it’s a. we all share. animals, plants and. let’s live together in harmony In ourselves we must take. for our. we need. Be kind it’s. . the world up with your. Mother Earth, Mother Earth It’s a.place to be! Words: Earth(2), place, planet, you, me, peace, harmony, with care, pride, to be, future, great, smile, to strive, smile, light, worthwhile, trees, humans
