Edge welded bellow.

It is known an opinion that the leading position of a country is estimated not only by its computerization but also by development and availability in it of modern membrane structures, including bellows. That is why for the last three years the Internet information just of edge welded bellows increased 40 times! If 25 years ago every industrially developed country had up to 10 companies which designed and manufactured bellows, now such companies in the USA alone amount to several hundreds.

Generally speaking, bellows may be produced from metals and non-metal materials, like plastics and rubber. We shall consider metal bellows, reminding that they belong to the so-called flexible, goffered, tubes - "accordeons". They are used in such industries as aircraft, automobile, medical, chemical, electronic, marine, military, nuclear, petrochemical, pharmaceutical, power generation, semiconductor, ultra high vacuum, etc.

The main bellows applications are:

Pair of bellow membrane.

Among two main bellows types - rolled and welded - the last is more perspective because of many more possibilities in design configurations, materials using, characteristics of flexibility, minimal length while a bellow is squeezed, etc. The welded bellows are mostly edge connected structures, and they consist of many preformed metal diaphragms. Such diaphrams are firstly welded inside - in pairs. The device for such pairs coupling is given at our equipment - other rubric. Then these pairs are welded outside - as far as the bellow length needs. We invented a special device for this purpose which is shown at the mentioned earlier rubric. Of course, each ready-made bellow has at its ends the armature produced from thicker, more suitable, material which permits to connect it to other structures easier, safer and quicker. Many interesting bellow structures everybody can find in Internet, for example, like in www.thomasnet.com/products/bellows-edge-welded-metal-95970299-1.html, www.ornl.gov/sci/fed/sofe05/summary/abs/072.pdf, www.kinemotive.com/edge _welded_bellows.htm. The edge welded bellows structure and their applications are partly but intelligibly shown in www.lasertechllc.com/LaserBellows.pdf.

As you may read in our unique innovations the usual (so-called standard) edge weld has at its root the obvious place of concentration of tension - at the plain of tightly put into contact metal diaphragms. Our research (31) showed that - due to these places of tension concentration - even under static load, the strength of "ideal" edge welds of thin metal foil is no more than 70 - 85% of the strength of the base material. Using new microplasma methods and equipment (like as the modular-inverter AMC-1 welder), we increased static strength of edge joint under stretch of 10-12%. It is clear that under cyclyc or dynamic loads this increase will be essentially higher, and such Edge Welded Technologies (EWT) have perspectives for improving properties of many thin-walled constructions.That is why the Kuibishev (Samara) Aircraft Institute had been interested in the new EWT and equipment. This institute suggested to produce modernized bellows as a base for a new Stirling's engine. If standard bellows have a design life of 10,000 cycles, we suggested to develop the new one with working resource in excess of 1-2 million cycles. Unfortunately, our cooperation in this field was ceased because the mentioned institute had no money. Not long ago some American companies showed interest in development of our EWT, and we would be glad to cooperate with them in this direction. We have also to underline that the proposed new EWT may be successfully applied for such bellow types as flat, plate, nesting ripple, single sweep and other.

The simpest membrane structure.

Because of a big tolerance to the gaps between the edges, new edge welded technologies can essentially increase the quality of any membrane structure - like is shown at the picture. Usually it is a problem for the conventional microplasma equipment, and on the "Pro-Fusion Technologies , Inc" specialists opinion, argon welding "..is generally "softer" than a corresponding plasma arc. As such, many bellows welding organizations prefer the TIG process for welding the outer diameters of the bellows because it is more forgiving if heat sink tooling is not in intimate contact with the bellows material". We have another opinion due to the unique possibilities of the AMC-1 welder.

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