The History of Electron Beam Technology
It has come a long way, from the pioneering work of British physicists Hittorf and Crooks in 1871-72 to invent cathode rays in gases and melted metals, to the successful production of computer-controlled manufacturing equipment for the modern aerospace industry.
Cathode rays were first described by Wilhelm Rontgen(1895), Thompson(1897), and Milikan(1905) as “fast-moving electrons.” The production of cathode rays generate a physical phenomenon of interest, but they are not considered useful for material processing. On the contrary, in all experiments that produce cathode rays, the heat created by the collision of electrons on the anode or target will cause great inconvenience, so water cooling is needed to prevent the anode or target from being melted by high temperatures.
Oscilloscopes and electron microscopes were the first truly meaningful applications of electron beam technology. Although Von Ardenne and Ruhle had begun drilling metal by evaporation and melting in 1938, lack of sufficiently powerful vacuum pumps,so electron beam can not be used on a larger scale.
In 1949, the German physicist Karl-Heinz Steigerwald ushered in a new era of material processing by utilizing electron beams. When Steigerwald was developing high-performance electron microscopes, he discovered that electron beams in vacuum , can be not only used as heat source tool for drilling jewelry and extruding molds during the period of making watch, but also can be used for brazing, metal melting and welding under vacuum.
This was the first electron beam drilling machine created by the German physicist Karl-Heinz Steigerwald.
In 1958, Steigerwald successfully completed the butt welding of a 5mm thick zirconium plate, thus industrial electron beam welding saw dramatic breakthroughs. Very deep and unexpectedly narrow welds, can be created under the condition of increasing electron beam current. These deep and narrow welds have generated new interest around the world.
After the discovery of the deep welding effect, new welding process equipment began to flourish by using this technology, especially in France and the United Kingdom. Electron beam welding can weld thinner work-pieces, as well as enlarge the welding depth by increasing the power density and current. Therefore, the first practical applications of electron beam welding, appeared in the aerospace and nuclear industry.
Electron Beam Welding Milestones in the history of equipment and process technology include:
- To realize the high-voltage cable connection without insulating oil of the electron gun;
- Use special tooling to achieve precise replacement of the cathode heating filament;
- Realize vacuum isolation between electron gun and vacuum chamber;
- Welding equipment with large vacuum chamber and vacuum pump group appears;
- Transfer and circulating welding equipment for mass production appears.
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