Development History of Flexible Metal Hose
Development history of flexible metal hose
At first, people sewed animal skins into tubular structures to meet the needs of production struggle. After a long period of time, by the end of the 17th century, van der gegin brothers of the Netherlands made longitudinally sewn canvas hose, which was widely used in the fire fighting business at that time. Later, with the appearance of rubber in the international market and the development of vulcanization technology, rubber hose and rubber hose armored with fabrics such as wire or hemp rope came out. However, in engineering, some high-temperature media such as steam and hot air, such as liquid hydrogen, liquid oxygen and liquid helium, and corrosive media such as gasoline, kerosene, acid and alkali, can not be transported by hose. Especially in the high temperature conditions, its safety and reliability is more difficult to guarantee.
Therefore, people gradually pay attention to the metal pipe, change the geometry of the metal pipe, so that the inner and outer surface of the corresponding ripple. In this way, it not only has the same flexibility as the hose, but also has high temperature resistance, low temperature resistance, aging resistance and corrosion resistance. Thus, as the metal hose body, the metal bellows is thus produced.
In 1855, Germany first published a patent for manufacturing bellows. It uses the principle of jewelry manufacturing to make bellows. Thirty years later, e. levavas seur of France cooperated with H. witzenmann of Germany to develop a new type of metal bellows. In August 1885, he obtained patents from France and Germany. This is a spiral corrugated pipe made of S-shaped metal belt on special equipment. They are padded with rubber belt, cotton fabric or asbestos rope at the bite of two adjacent turns to facilitate the sealing of the inner cavity of the corrugated pipe.
In 1894, the structure of this kind of bellows was improved: two metal belts were wound in opposite directions according to different diameters. In this way, the metal belt can achieve mutual balance in the stress state, and overcome the disadvantages of self-development.
In 1929, another technological revolution was carried out in the structure of bellows, which completely solved the problem of bellows losing sealing performance due to uneven change of grooves filled with rubber belt or asbestos rope during bending, thus opening up a broad prospect for the development of bellows. People have made integral bellows with steel and copper zinc alloy materials, that is, bellows made of seamless or welded pipes. It depends on the elastic deformation of the corrugated side wall to maintain certain compressibility or extensibility, and at the same time, it ensures reliable sealing.
Since the 1950s, double-layer, three-layer and multi-layer bellows, especially the extremely thin-walled stainless steel bellows, have developed rapidly. In order to meet the use requirements, people use welding, electroforming, machining, hydraulic and mechanical spinning and other processes to manufacture bellows. The minimum nominal diameter is 2 mm, the maximum nominal diameter can reach 400 ~ 500 mm, and there are even giant bellows with a diameter of 10 meters. The number of corrugations is at least 1-2, and can be up to hundreds, thousands, even tens of thousands.
From the important significance of bellows as flexible metal hose body. The development of metal bellows means the development of metal hose. Then, the corrugated pipe was covered with rubber, plastic or nylon and other materials, and the net cover was made of metal wire or metal belt. All kinds of joint forms were changed. In order to adapt to different requirements under various conditions, various forms of metal hose were created.
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