Текст «Сварка»
В этом тексте говорится о процессах сварки. Сварка представляет собой процесс, когда металлические части соединены друг с другом под воздействием тепла, давления, или комбинации обоих.
Процессы сварки можно разделить на две основные группы:
• сварка давлением, когда сварной шов достигается за счет давления и
• сварка нагреванием, когда сварной шов достигается за счет тепла. Сварка нагреванием является наиболее распространенным процессом сварки, использущимся сегодня.
Сварочные процессы, широко используемые в настоящее время, включают газовую сварку, дуговую сварку и контактную сварку. Другие соединительные процессы: лазерная сварка и электронно-лучевая сварка.
Газовая сварка
Здесь говорится о газовой сварке. Газовая сварка это процесс не под давлением с использованием тепла от пламени газа. Газовая сварка имеет то преимущество, что используется оборудование, которое является портативным и не требует источника электроэнергии
Дуговая сварка
Здесь говорится о дуговой сварке. Дуговая сварка является самым важным процессом сварки для соединения сталей. Эта сварка имеет ряд преимуществ перед другими методами сварки. Дуговая сварка быстрее, потому что концентрация тепла высока. Кроме того, флюс не является необходимым в определенных методах дуговой сварки.
Дуговая сварка в защищенном металле
Здесь говорится о дуговой сварке в защищенном металле. В дуговой сварке в защищенном металле, металлический электрод, который проводит электричество, покрыт флюсом и подключен к источнику электрического тока. Этот процесс используется в основном для сварки сталей.
Реферативный перевод (Англ.)
Text A: «WELDING»
Welding is a process when metal parts are joined together by the application of heat, pressure, or a combination of both. The processes of welding can be divided into two main groups:
• pressure welding, when the weld is achieved by pressure and
• heat welding, when the weld is achieved by heat. Heat welding is the most common welding process used today.
Nowadays welding is used instead of bolting and riveting in the construction of many types of structures, including bridges, buildings, and ships. It is also a basic process in the manufacture of machinery and in the motor and aircraft industries. It is necessary almost in all productions where metals are used.
The welding process depends greatly on the properties of the metals, the purpose of their application and the available equipment. Welding processes are classified according to the sources of heat and pressure used.
The welding processes widely employed today include gas welding, arc welding, and resistance welding. Other joining processes are laser welding, and electron-beam welding.
Until the end of the 19th century, the only welding process was forge welding, which blacksmiths had used for centuries to join iron and steel by heating and hammering. Arc welding and oxyfuel welding were among the first processes to develop late in the century, and electric resistance welding followed soon after. Welding technology advanced quickly during the early 20th century as World War I and World War II drove the demand for reliable and inexpensive joining methods. Following the wars, several modern welding techniques were developed, including manual methods like shielded metal arc welding, now one of the most popular welding methods, as well as semi-automatic and automatic processes such as gas metal arc welding, submerged arc welding, flux-cored arc welding and electroslag welding. Developments continued with the invention of laser beam welding, electron beam welding, magnetic pulse welding (MPW), and friction stir welding in the latter half of the century. Today, the science continues to advance. Robot welding is commonplace in industrial settings, and researchers continue to develop new welding methods and gain greater understanding of weld quality.
Gas Welding
Gas welding is a non-pressure process using heat from a gas flame. It is one of the oldest welding processes, besides forge welding. Still used in industry, in recent decades it has been less widely utilized in industrial applications as other specifically devised technologies have been adopted. It is still widely used for welding pipes and tubes, as well as repair work. It is also frequently well-suited, and favored, for fabricating some types of metal-based artwork. As well, oxy-fuel has an advantage over electric welding and cutting processes in situations where accessing electricity (e.g., via an extension cord or portable generator) would present difficulties; it is more self-contained, in this sense — hence "more portable". The flame is applied directly to the metal edges to be joined and simultaneously to a filler metal in the form of wire or rod, called the welding rod, which is melted to the joint. Gas welding has the advantage of using equipment that is portable and does not require an electric power source. The surfaces to be welded and the welding rod are coated with flux, a fusible material that shields the material from air, which would result in a defective weld.
Arc Welding
Arc-welding is the most important welding process for joining steels. It requires a continuous supply of either direct or alternating electrical current. This current is used to create an electric arc, which generates enough heat to melt metal and create a weld.
Arc welding has several advantages over other welding methods. Arc welding is faster because the concentration of heat is high. Also, fluxes are not necessary in certain methods of arc welding. The most widely used arc welding processes are shielded metal arc, gas-tungsten arc, gas-metal arc, and submerged arc. The direction of current used in arc welding also plays an important role in welding. Consumable electrode processes such as shielded metal arc welding and gas metal arc welding generally use direct current, but the electrode can be charged either positively or negatively. In welding, the positively charged anode will have a greater heat concentration and, as a result, changing the polarity of the electrode has an impact on weld properties. If the electrode is positively charged, it will melt more quickly, increasing weld penetration and welding speed. Alternatively, a negatively charged electrode results in more shallow welds. Non-consumable electrode processes, such as gas tungsten arc welding, can use either type of direct current (DC), as well as alternating current (AC). With direct current however, because the electrode only creates the arc and does not provide filler material, a positively charged electrode causes shallow welds, while a negatively charged electrode makes deeper welds. One disadvantage of AC, the fact that the arc must be reignited after every zero crossing, has been addressed with the invention of special power units that produce a square wave pattern instead of the normal sine wave, eliminating low-voltage time after the zero crossings and minimizing the effects of the problem.
Shielded Metal Arc
In shielded metal-arc welding, a metallic electrode, which conducts electricity, is coated with flux and connected to a source of electric current. The metal to be welded is connected to the other end of the same source of current. An electric arc is formed by touching the tip of the electrode to the metal and then drawing it away. The intense heat of the arc melts both parts to be welded and the point of the metal electrode, which supplies filler metal for the weld. This process is used mainly for welding steels. Because of the versatility of the process and the simplicity of its equipment and operation, shielded metal arc welding is one of the world's most popular welding processes. It dominates other welding processes in the maintenance and repair industry, and though flux-cored arc welding is growing in popularity, SMAW continues to be used extensively in the construction of steel structures and in industrial fabrication. The process is used primarily to weld iron and steels (including stainless steel) but aluminium, nickel and copper alloys can also be welded with this method.[2]
Реферативный перевод (Рус.)