Semiautomatic submerged-arc welding
Semiautomatic submerged-arc welding.
The semiautomatic submerged arc process – with many outstanding advantages over conventional hand welding methods including speeds up to 4 times greater – is every year finding wider and wider application, both in the shop and in the field.
Equipment. The available equipment for this process is semiautomatic in that the electrode is a continuous wire which is fed to the work mechanically. It is called submerged arc because a granular flux composition is spread just ahead of the electrode and the arc is invisible under this flux. An operator has the conical flux container in his hand and welding nozzle through which the electrode is fed. A separate unit contains the continuous electrode supply, the motor used to power it, and the controls for feeding the electrode and for maintaining the proper arc voltage. The source of welding power is usually a d-c generator although some makes use a rectifier or A-C transformer.
One of the great advantages of semiautomatic welding is the very high melting rate at high currents. In the semiautomatic range, the lower melting rate occurs when electrode is positive and the higher melting rate when electrode is negative. It will be noted that electrode negative is as much 45% higher in deposition rate than positive polarity at these densities.
The combination of higher melting rate and greater penetration obtained enables vast increases in speed for equal strength with semiautomatic over hand welding.
In comparison with fully-automatic method has these advantages: 1) it can manually follow irregular shapes, 2) no fixtures, or only simple fixtures, are required, 3) it can handle a great variety of jobs and is easily portable, and 4) its first cost is lower.
Пользуясь выше приведённым текстом, выполните следующие задания.
1. Составьте 10 специальных вопросов и устно ответьте.
2. Составьте аннотацию текста из 5 предложений.
3. Дайте определения следующим терминам по-английски: build up, electrode, flux, container, nozzle, voltage, generator, rectifier, transformer, slag.
4. Переведите на русский язык следующие термины, подчеркните главное слово: granular flux composition, conical flux container, direct current generator, alternating current transformer, submerged-arc welding, high melting rate, fully-automatic welding, electrode feed control, single electrode welding, multy-electrode welding.
5. Составьте десять предложений в соответствии с тематикой текста, используя инфинитив и придаточные предложения.
6. Подчеркните инфинитив и придаточные предложения: 1. The pressure is then maintained for at least sufficient time for the metal to cool and permit recrystallization. 2. Equipment modification to provide this greater power capability did not involve changes in basic electron optical concepts. 3. In this process the piece to be welded are clamped between electrodes made of a copper alloy. 4. Electro slag welding is known to join all types of steels, from low or medium-carbon structural to ultra-high strength steels as well as the stainless steels and high nickel alloys. 5. We know Russian Academician V.V. Petrov to discover the phenomenon of the arc discharge and the possibility of using the temperature of the arc (about 6000°C) to melt metals. 6. The talented Russian engineer N.N. Bernardos was the first to patent the arc welding method using a carbon electrode. 7. American patents on the metal arc process were issued to Charles Coffin in 1889, but N.N. Slavianoff is known to be the first to propose a consumable metal electrode. 8. The first thing for welders to do is to learn safety rules. 9. The experiment which is said to be of great importance for this branch of industry should be discussed at our conference.
Контрольная по английскому предназначена для тех, кто учится в технических вузах. Контрольная по английскому небольшая. Контрольная по силам любому студенту.
