Specialists from NPO Lavochkin, together with colleagues from the All-Russia Research Institute of Experimental Physics in Sarov and with the support of Professor Antonio Lapucci from the Institute of Applied Optics in Florence, Italy and Director of the Welding Institute in Aachen (Germany) Professor Ulrich Delthey, are developing a completely new light-laser welding system with the use of powerful polychromatic energy sources. This makes it possible to avoid the shortcomings of laser welding that were previously thought to be unavoidable. Financial support for the project comes from the International Science and Technology Centre.
The complex, the first experimental version of which has already been constructed and is being tested by scientists from this world-famous space science and technology centre, involves two energy sources, a Nd-YAG-laser (a neodymium-yttrium aluminium garnet laser), which is what performs the spot weld itself, and a special light module, a powerful source of light, the spectrum of which can be altered. And, of course, there is the requisite equipment and the corresponding software, which enables automatic welding over a pre-set program.
The crux of the method indeed lies in the use of this second, light source of radiation. Its power and spectral attributes are such that it can quickly and effectively heat a weld area and its surrounding space to a temperature, if required, to over 1000 degrees. In its turn, this is a guarantee that defects that form under the welding of cold (that is specially non-heated) parts are significantly fewer, while the need for annealing ready products is eradicated altogether.
Indeed, welders have long since known that the quality of a weld-join is essentially better if the parts to be welded are well heated. Cases have even been known when large metal parts are welded even before they have cooled after smelting. But how can you heat parts sufficiently quickly and effectively if one of them is made, for example, from invar (an iron-nickel alloy), which hardly alters its dimensions when heated, and the other is made from glass? How can they be heated to high temperatures without damaging them?
To resolve this problem, Doctor of Technical Sciences Valentin Sysoev and his colleagues proposed the use of a powerful lamp where, shining the beam of this lamp on the surface to be welded, can heat the item to the required temperature. In principle, such sources of energy could be the only ones to use for welding, only the excessively large diameter of the light beam (up to 2-3mm) and certain other features mean that they cannot be used for spot welding. However, the scientists believe that using them not for welding but for heating ? surface, inside which a narrow laser beam will perform the spot weld, is not only possible, but also very necessary. The fall in temperature between the point of the weld and around it will be much smoother, and this is what defines the exceptionally high quality of the weld.
If we take account of the fact that a combined approach of this kind can use weaker lasers, than those that are traditionally applied, it will transpire that this new method is not only more effective, but is also more economical as the price of lasers is proportionate to their power. So it can be hoped that in the very near future the process of laser welding of car chassis and other items of importance to us all will be better and cheaper. The guarantee for this is the very highest level of professionalism of the team of scientists on this project and the financial support provided to the scientists by the ISTC.
