Metal bellows
Metal bellows , annular cylinder made of metal having a wavy varying diameter, so as metal bellows or corrugated metal pipes are referred to.
They are used as a corrugated pipe expansion joint in pipes and fittings , as a metal bellows coupling between shafts , as a separating membrane in hydraulic accumulators and for other purposes.
The bellows are made from thin-walled tubes , which are continuously made from thin strips (0.1 to 0.8 mm) by longitudinal seam welding . The subsequent shaping into a corrugated pipe can be done isostatically , hydraulically or mechanically by rolling.
All cold deformable and weldable materials are processed.
The bellows are used to compensate for movements in the axial or lateral direction and to compensate for angular deviations in the geometrical axes of the flanges. Torques are transmitted rigidly and without play.
Multi-layer bellows
To increase and stability while maintaining flexibility, metal bellows are also manufactured in multiple layers. Several thin metal layers are used as the wall of the bellows. The combination of different materials has further advantages. If one of the layers is damaged over time, the remaining gas-tight layers prevent the medium from escaping.
For the transport of aggressive media, the inner layer can be made of a corrosion-resistant material, while the outer layers are made of mechanically more favorable materials.
Applications
Flexible pipe connection
So-called decoupling elements (see also corrugated pipe compensator ) based on metal bellows are used on traction and aircraft engines, including in the exhaust system of motor vehicles, to decouple unit vibrations.
Miniature bellows are used as sealing elements in piezo injection systems and valve drives. In piezo injection systems (200 bar operating pressure), each bellows element undergoes over a billion load changes during the entire service life of the vehicle.
Since corrugated pipes can also withstand external pressure, they can also be found in vacuum systems.
The differential pressure between inside and outside leads to an axial force that has to be taken into account in the design or can also be used.
Pump and working cylinders
Gas-tight metal bellows are used as pressure accumulators for braking energy in vehicles with hybrid drives.
In medical technology, miniature bellows are used in insulin pump implants.
Heat exchanger
Corrugated hoses made of metal are also used in heat exchangers due to their large specific surface .
Torque transmission
In machine tool construction and precision engineering , metal bellows couplings are used as permanent coupling elements for backlash-free direct power transmission of the starting and operating torque and simultaneous compensation of axial offset.
literature
- Werner Kriesel : ursastat - measuring sensor with relay output (relay transmitter) and regulator without auxiliary energy (direct regulator). In: Haas, H., Bernicke, E., Fuchs, H., Obenhaus, G. (overall editor): ursamat-Handbuch , published by the Institute for Control Engineering Berlin. Verlag Technik, Berlin 1969.
- Heinz Töpfer , Werner Kriesel : Small automation through devices without auxiliary energy. Volume 173 of the series automation technology, Verlag Technik, Berlin 1976, 2nd edition 1978 (with Ekkehard Reimann and Mertik Quedlinburg ).
- Heinz Töpfer , Werner Kriesel : Functional units of automation technology - electrical, pneumatic, hydraulic. Verlag Technik, Berlin and VDI-Verlag, Düsseldorf 1977, 5th edition 1988, ISBN 3-341-00290-1 .
- Werner Kriesel : Automatic Museum in Leipzig. In: Association of German Engineers, VDI / VDE-GMA (Hrsg.): Yearbook 1997 VDI / VDE-Gesellschaft Mess- und Automatisierungstechnik. VDI-Verlag, Düsseldorf 1997, ISBN 3-18-401611-0 .
