Posts : 409
Join date : 2011-06-10
|Subject: voltage to regulate Thu Jun 23, 2011 4:49 pm|| |
The principles of gas metal arc welding began to be understood in the early 19th century, after Humphry Davy discovered the short pulsed electric arcs in 1800 and then Vasily Petrov independently produced the continuous electric arc in 1802 (soon followed by Davy). In his work published in 1803 Petrov proposed the usage of electric arc in welding, having managed to perform a simple experimental welding. But it was not until the 1880s that the technology became developed with the aim of industrial usage. At first, the practical method of carbon arc welding invented by Nikolay Benardos was used, utilising carbon electrodes known from the time of Davy and Petrov. By the late 1880s, metal electrodes had been invented by Nikolay Slavyanov (1888) and C. L. Coffin (1890). In 1920, an early predecessor of GMAW was invented by P. O. Nobel of General Electric. It used a bare electrode wire and direct current, and used arc voltage to regulate the feed rate. It did not use a shielding gas to protect the weld, as developments in welding atmospheres did not take place until later that decade. In 1926 another forerunner of GMAW was released, but it was not suitable for practical use.
It was not until 1948 that GMAW was finally developed by the Battelle Memorial Institute. It used a smaller diameter electrode and a constant voltage power source, which had been developed by H. E. Kennedy. It offered a high deposition rate, but the high cost of inert gases limited its use to non-ferrous materials and cost savings were not obtained. In 1953, the use of carbon dioxide as a welding atmosphere was developed, and it quickly gained popularity in GMAW, since it made welding steel more economical. In 1958 and 1959, the short-arc variation of GMAW was released, which increased welding versatility and made the welding of thin materials possible while relying on smaller electrode wires and more advanced power supplies. It quickly became the most popular GMAW variation. The spray-arc transfer variation was developed in the early 1960s, when experimenters added small amounts of oxygen to inert gases. More recently, pulsed current has been applied, giving rise to a new method called the pulsed spray-arc variation.best home business opportunityVAPORIZER