Elastic Nature of Bellows Tubes

Bellows tubes are elastic vessels that can be compressed when pressure is applied to the outside of the vessel or extended under vacuum. When the pressure or vacuum is released, the bellows return to their original shape. These are also known as convoluted bellows or sylphons.

Applications of Metal Bellows

Bellows, either welded or convoluted (formed), are used in a wide range of industrial applications including load cells, mechanical seals, valve sealing, exhaust bellows, and piping expansion joints. Metal bellows are also used in medical applications such as implantable drug pumps, industrial actuators, and aerospace applications including altitude sensors and fluid management devices like accumulators, surge arresters, volume compensators, and fluid storage systems. They are further used in space applications for potable water storage and wastewater collection.

Types of Metal Bellows

There are two main types of metal bellows: formed bellows and welded bellows. Formed bellows are manufactured using processes such as cold forming (rolling), electroforming, and hydroforming.

Ripple (Convolution) Forming Process

Bellows tubes or ripples are produced through a combined process of bulging and collapsing. Initially, the tube is pressed using a hydraulic or mechanical press, causing bulging at several fixed and equidistant locations.

Axial Compression and Ripple Formation

In the next step, axial compression is applied to crumple the bulged regions, thereby forming bellows or ripples. The tube material must withstand large deformation during the collapsing process; therefore, mild steel is used in the simulation of the tube ripple process.