Сборник технических текстов с заданиями для профессии 15. 01. 05 «Сварщик» (ручной и частично механизированной сварки (наплавки)
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History of WeldingMiddle Ages Welding can trace its historic development back to ancient times. The earliest examples come from the Bronze Age. Small gold circular boxes were made by pressure welding lap joints together. It is estimated that these boxes were made more than 2000 years ago. During the Iron Age the Egyptians and people in the eastern Mediterranean area learned to weld pieces of iron together. Many tools were found which were made approximately 1000 B.C. During the Middle Ages, the art of blacksmithing was developed and many items of iron were produced which were welded by hammering. It was not until the 19th century that welding, as we know it today was invented. 1800 Edmund Davy of England is credited with the discovery of acetylene in 1836. The production of an arc between two carbon electrodes using a battery is credited to Sir Humphry Davy in 1800. In the mid-nineteenth century, the electric generator was invented and arc lighting became popular. During the late 1800s, gas welding and cutting was developed. Arc welding with the carbon arc and metal arc was developed and resistance welding became a practical joining process. 1880 Auguste De Meritens, working in the Cabot Laboratory in France, used the heat of an arc for joining lead plates for storage batteries in the year 1881. It was his pupil, a Russian, Nikolai N. Benardos, working in the French laboratory, who was granted a patent for welding. He, with a fellow Russian, Stanislaus Olszewski, secured a British patent in 1885 and an American patent in 1887. The patents show an early electrode holder. This was the beginning of carbon arc welding. Bernardos' efforts were restricted to carbon arc welding, although he was able to weld iron as well as lead. Carbon arc welding became popular during the late 1890s and early 1900s. 1890 In 1890, C.L. Coffin of Detroit was awarded the first U.S. patent for an arc welding process using a metal electrode. This was the first record of the metal melted from the electrode carried across the arc to deposit filler metal in the joint to make a weld. About the same time, N.G. Slavianoff, a Russian, presented the same idea of transferring metal across an arc, but to cast metal in a mold. 1900 Approximately 1900, Strohmenger introduced a coated metal electrode in Great Britain. There was a thin coating of clay or lime, but it provided a more stable arc. Oscar Kjellberg of Sweden invented a covered or coated electrode during the period of 1907 to 1914. Stick electrodes were produced by dipping short lengths of bare iron wire in thick mixtures of carbonates and silicates, and allowing the coating to dry. Meanwhile, resistance welding processes were developed, including spot welding, seam welding, projection welding and flash butt welding. Elihu Thompson originated resistance welding. His patents were dated 1885-1900. In 1903, a German named Goldschmidt invented thermite welding that was first used to weld railroad rails. Gas welding and cutting were perfected during this period as well. The production of oxygen and later the liquefying of air, along with the introduction of a blow pipe or torch in 1887, helped the development of both welding and cutting. Before 1900, hydrogen and coal gas were used with oxygen. However, in about 1900 a torch suitable for use with low-pressure acetylene was developed. World War I brought a tremendous demand for armament production and welding was pressed into service. Many companies sprang up in America and in Europe to manufacture welding machines and electrodes to meet the requirements. 1919 Immediately after the war in 1919, twenty members of the Wartime Welding Committee of the Emergency Fleet Corporation under the leadership of Comfort Avery Adams, founded the American Welding Society as a nonprofit organization dedicated to the advancement of welding and allied processes. Alternating current was invented in 1919 by C.J. Holslag; however it did not become popular until the 1930s when the heavy-coated electrode found widespread use. 1920 In 1920, automatic welding was introduced. It utilized bare electrode wire operated on direct current and utilized arc voltage as the basis of regulating the feed rate. Automatic welding was invented by P.O. Nobel of the General Electric Company. It was used to build up worn motor shafts and worn crane wheels. It was also used by the automobile industry to produce rear axle housings. During the 1920s, various types of welding electrodes were developed. There was considerable controversy during the 1920s about the advantage of the heavy-coated rods versus light-coated rods. The heavy-coated electrodes, which were made by extruding, were developed by Langstroth and Wunder of the A.O. Smith Company and were used by that company in 1927. In 1929, Lincoln Electric Company produced extruded electrode rods that were sold to the public. By 1930, covered electrodes were widely used. Welding codes appeared which required higher-quality weld metal, which increased the use of covered electrodes. During the 1920s there was considerable research in shielding the arc and weld area by externally applied gases. The atmosphere of oxygen and nitrogen in contact with the molten weld metal caused brittle and sometime porous welds. Research work was done utilizing gas shielding techniques. Alexander and Langmuir did work in chambers using hydrogen as a welding atmosphere. They utilized two electrodes starting with carbon electrodes but later changing to tungsten electrodes. The hydrogen was changed to atomic hydrogen in the arc. It was then blown out of the arc forming an intensely hot flame of atomic hydrogen during to the molecular form and liberating heat. This arc produced half again as much heat as an oxyacetylene flame. This became the atomic hydrogen welding process. Atomic hydrogen never became popular but was used during the 1930s and 1940s for special applications of welding and later on for welding of tool steels. H.M. Hobart and P.K. Devers were doing similar work but using atmospheres of argon and helium. In their patents applied for in 1926, arc welding utilizing gas supplied around the arc was a forerunner of the gas tungsten arc welding process. They also showed welding with a concentric nozzle and with the electrode being fed as a wire through the nozzle. This was the forerunner of the gas metal arc welding process. These processes were developed much later. 1930 Stud welding was developed in 1930 at the New York Navy Yard, specifically for attaching wood decking over a metal surface. Stud welding became popular in the shipbuilding and construction industries. The automatic process that became popular was the submerged arc welding process. This "under powder" or smothered arc welding process was developed by the National Tube Company for a pipe mill at McKeesport, Pennsylvania. It was designed to make the longitudinal seams in the pipe. The process was patented by Robinoff in 1930 and was later sold to Linde Air Products Company, where it was renamed Unionmelt® welding. Submerged arc welding was used during the defense buildup in 1938 in shipyards and in ordnance factories. It is one of the most productive welding processes and remains popular today. 1940 Gas tungsten arc welding (GTAW) had its beginnings from an idea by C.L. Coffin to weld in a nonoxidizing gas atmosphere, which he patented in 1890. The concept was further refined in the late 1920s by H.M.Hobart, who used helium for shielding, and P.K. Devers, who used argon. This process was ideal for welding magnesium and also for welding stainless and aluminum. It was perfected in 1941, patented by Meredith, and named Heliarc® welding. It was later licensed to Linde Air Products, where the water-cooled torch was developed. The gas tungsten arc welding process has become one of the most important. The gas shielded metal arc welding (GMAW) process was successfully developed at Battelle Memorial Institute in 1948 under the sponsorship of the Air Reduction Company. This development utilized the gas shielded arc similar to the gas tungsten arc, but replaced the tungsten electrode with a continuously fed electrode wire. One of the basic changes that made the process more usable was the small-diameter electrode wires and the constant-voltage poser source. This principle had been patented earlier by H.E. Kennedy. The initial introduction of GMAW was for welding nonferrous metals. The high deposition rate led users to try the process on steel. The cost of inert gas was relatively high and the cost savings were not immediately available. 1950 In 1953, Lyubavskii and Novoshilov announced the use of welding with consumable electrodes in an atmosphere of CO2 gas. The CO2 welding process immediately gained favor since it utilized equipment developed for inert gas metal arc welding, but could now be used for economically welding steels. The CO2 arc is a hot arc and the larger electrode wires required fairly high currents. The process became widely used with the introduction of smaller-diameter electrode wires and refined power supplies. This development was the short-circuit arc variation which was known as Micro-wire®, short-arc, and dip transfer welding, all of which appeared late in 1958 and early in 1959. This variation allowed all-position welding on thin materials and soon became the most popular of the gas metal arc welding process variations. 1960 Another variation was the use of inert gas with small amounts of oxygen that provided the spray-type arc transfer. It became popular in the early 1960s. A recent variation is the use of pulsed current. The current is switched from a high to a low value at a rate of once or twice the line frequency. Soon after the introduction of CO2 welding, a variation utilizing a special electrode wire was developed. This wire, described as an inside-outside electrode, was tubular in cross section with the fluxing agents on the inside. The process was called Dualshield®, which indicated that external shielding gas was utilized, as well as the gas produced by the flux in the core of the wire, for arc shielding. This process, invented by Bernard, was announced in 1954, but was patented in 1957, when the National Cylinder Gas Company reintroduced it. In 1959, an inside-outside electrode was produced which did not require external gas shielding. The absence of shielding gas gave the process popularity for noncritical work. This process was named Innershield®. The electroslag welding process was announced by the Soviets at the Brussels World Fair in Belgium in 1958. It had been used in the Soviet Union since 1951, but was based on work done in the United States by R.K. Hopkins, who was granted patents in 1940. The Hopkins process was never used to a very great degree for joining. The process was perfected and equipment was developed at the Paton Institute Laboratory in Kiev, Ukraine, and also at the Welding Research Laboratory in Bratislava, Czechoslovakia. The first production use in the U.S. was at the Electromotive Division of General Motors Corporation in Chicago, where it was called the Electro-molding process. It was announced in December 1959 for the fabrication of welded diesel engine blocks. The process and its variation, using a consumable guide tube, is used for welding thicker materials. The Arcos Corporation introduced another vertical welding method, called Electrogas, in 1961. It utilized equipment developed for electroslag welding, but employed a flux-cored electrode wire and an externally supplied gas shield. It is an open arc process since a slag bath is not involved. A newer development uses self-shielding electrode wires and a variation uses solid wire but with gas shielding. These methods allow the welding of thinner materials than can be welded with the electroslag process. Gage invented plasma arc welding in 1957. This process uses a constricted arc or an arc through an orifice, which creates an arc plasma that has a higher temperature than the tungsten arc. It is also used for metal spraying and for cutting. The electron beam welding process, which uses a focused beam of electrons as a heat source in a vacuum chamber, was developed in France. J.A. Stohr of the French Atomic Energy Commission mad the first public disclosure of the process on November 23, 1957. In the United States, the automotive and aircraft engine industries are the major users of electron beam welding. Most Recent Friction welding, which uses rotational speed and upset pressure to provide friction heat, was developed in the Soviet Union. It is a specialized process and has applications only where a sufficient volume of similar parts is to be welded because of the initial expense for equipment and tooling. This process is called inertia welding. Laser welding is one of the newest processes. The laser was originally developed at the Bell Telephone Laboratories as a communications device. Because of the tremendous concentration of energy in a small space, it proved to be a powerful heat source. It has been used for cutting metals and nonmetals. Continuous pulse equipment is available. The laser is finding welding applications in automotive metalworking operations. 4. Составьте конспект текста из упражнения 3. Unit 18 Welding: Fun Facts 1.Прочитайте и переведите текст. 1. NASCAR — Long before the rubber hits the road, roughly 950 man-hours are spent on welding and fabrication for each race car. Hundreds of parts are hand-cut, welded and machined, from the chassis and suspension to the drivetrain. 2. In 1961, General Motors installed the first industrial robot in history, the Unimate. Featuring a motorized arm that weighed more than two tons, the Unimate performed spot welds by following step-by-step commands stored on a magnetic drum. 3. Which famous comedian has a large antique car and motorcycle collection and employs welders regularly? Jay Leno! His large collection includes models from the early 1900s to modern vehicles. 4. Explosion welding is a powerful welding process that can accomplish what many other welding methods can’t—it can join nearly every kind of metal together, even the most highly dissimilar ones. 5. Welding in space was first attempted in 1969 by Russian cosmonauts. Today, advances in welding technology have made it essential for projects like the construction of the International Space Station. 6. President Roosevelt, in a letter to Prime Minister Winston Churchill, boasted about the discovery of new welding techniques that enabled America to build ships with a speed unequaled in the history of shipbuilding. 7. The first car made with an entirely plastic body was assembled using ultrasonic welding. Even though plastic cars did not catch on, ultrasonic welding did. Ultrasonic plastic welding is an example of a friction welding process, which creates energy through high-intensity acoustic sounds that cause plastic pieces to vibrate together and form a bond. 8. Did you know that if two pieces of metal touch in space, they become permanently stuck together? This may sound unbelievable, but it is true. Two pieces of metal without any coating on them will form into one piece in the vacuum of space. This doesn’t happen on Earth because the atmosphere puts a layer of oxidized material between the surfaces. 9. More than 50% of U.S. products require welding. Do you know which of the following products rely on welding?  Race cars Bridges Ships Computers Medical devices Oil rigs Farm equipment Cell phones Scooters MP3 players Answer: All of them 10. What is a “fume plume”? It is the visible column of fume that rises directly from the spot of welding or cutting. 11. The current record for the world’s deepest underwater dry weld, which is carried out in a chamber sealed around the structure to be welded, was set by Global Industries in 1990, at 1,075 ft. deep. But that is only half as deep as the world’s record wet weld, set by the U.S. Navy in 2005, at 2,000 ft. deep. Wet welding is performed underwater, directly exposed to the watery environment. 12. The earliest recorded welds occured in 3,500 B.C., the Bronze-Age. Pictures of welders and their ancient tools have been discovered in long-sealed Egyptian tombs! Unit19 Machine – tools 1.Запишите новые слова и составьте с ними свои предложения. shape - форма casting - отливка rolling - прокат welding - сварка piercing - прохождение trimming - обрезка (заделка отверстия краев) spinning - выдавливание (на токарно-давильном станке) drawing - черчение; зд. вытягивание chuck - зажим; патрон, держатель carriage - каретка milling - фрезерование surface - поверхность grinding - дробление (измельчение), шлифовка convenient - удобный to equip - снаряжать, оборудовать shaping - придание формы thread - резьба; нарезка bending – сгибание headstock - передняя бабка tailstock - задняя бабка lathe - токарный станок drilling – сверление cutting – резание high-speed – скоростной efficient – эффективный forging – ковка boring - бурение, сверление steel - сталь 2.Прочтите тексты MACHINE-TOOLS Metal undergoes a number of processes before it is formed into the required shape: casting, rolling, welding, piercing, trimming, spinning, bending, drawing, etc. The machines which perform all these kinds of works are called machine-tools. The most common machine-tool found in almost any workshop is the lathe. The main parts of it are: the headstock, the chuck, the tailstock, the carriage. The automatic lathe is a perfection of the ordinary lathe. Its tools are changed automatically. A worker skilled in the use of a lathe is called a turner. There are many other machine-tools that work on plane surfaces, for example, milling machines, planning and shaping machines. Circular holes are drilled by a drilling machine or bored by a boring machine or a boring mill. Thread milling machines are used in the production of different machine elements. Gear cutting machines include gear milling machines. All these machines use cutting tools made of high-speed steel. LATHES There are three types of lathes produced by our machine-tool manufacturing works: heavy, medium and light types. The type of a lathe depends upon the size of diameter of work pieces. A most convenient and efficient machine is the model combination lathe for turning, milling, drilling, grinding, slotting, and tool-sharpening jobs. It can be used both in stationary and mobile repair shops, on ships, etc. DRILLING MACHINES The most drilling machines are equipped with mechanisms, permitting not only drilling, countersinking and reaming, but also cutting female threads with the help of taps. Both universal and special-purpose type radial "drills are built. 3.Ответьте письменно на вопросы
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